@article {3672,
	title = {Effect of breed on bone morphology in the distal metacarpus epiphysis of mature Angus and Angus crossbred cows},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {82},
	year = {2022},
	month = {01/2022},
	pages = {82-87},
	address = {Online},
	abstract = {There are variations in stature between beef and dairy breeds (and their crosses) which are an indirect result of genetic selection and farm management for different production objectives. The aim of this experiment was to examine the effect of breed on bone morphology in the distal epiphysis of the metacarpus. The metacarpus was collected from 9.5-year-old Angus (AA), Angus-Friesian crossbred (AF), Angus-Jersey crossbred (AJ) and Angus- (Friesian cross Jersey) crossbred (AK) cows. Bone morphology in the epiphysis was assessed using peripheral quantitative computed tomography (pQCT) for the medial and lateral condyles of the epiphysis 7 mm from the distal metacarpus. The greater total bone cross-sectional area of AA and AF could be associated with minimising strain on the articulating surface of the metacarpus due to greater joint surface area. Therefore, the greater total bone cross-sectional area may be an indirect result of a greater level of muscularity in beef breeds with a heavier mature weight.},
	issn = {1176-5283},
	author = {Gibson MJ and Hickson RE and Dittmer KE and Back PJ and Schreurs NM and Rogers CW}
}
@article {3672,
	title = {Defecation behaviour reduces horse{\textquoteright}s utilisation of pasture},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {81},
	year = {2021},
	month = {01/2022},
	pages = {74-80},
	address = {Online},
	abstract = {Horses kept at pasture create focal areas with high-density of faeces (latrines), which under commercial conditions can account for 30\% of total pasture area. This New Zealand study observed the utilisation of pasture, and establishment of lawns and roughs within one paddock, intensively grazed (semi-set-stocked) alternately by three herds of mixed-age (mature), predominately Standardbred, horses. The paddock was grazed by horses 480 of 730 days, with mean stocking density of four horses per ha (2148 kg live weight/ha). Median grazing duration was 44 days (IQR 37-47 days). The median overall pasture cover for the study period was 1114 kg DM/ha (range 496-2191 kg DM/ha), lawns was 683 kg DM/ha (range 389-1822 kg DM/ha), and roughs was 2058 (range 753-3971 kg DM/ha). There was a trend for greater post-grazing estimated pasture growth rates in roughs relative to the lawns (P=0.054). Latrine areas constituted a median 31\% (IQR 24-33\%) of available pasture area, with up to two faecal-piles/m2. The results of the current study suggest that intensive semi-set-stocked management promotes the establishment of easily identified latrine areas of moderate faecal-pile concentration. These data can contribute to modelling the nitrogen-holding capacity of the soil, nitrogen leaching and the efficient utilisation of pasture of grazing horses.

Keywords: equine; faeces; nitrogen; pasture},
	issn = {1176-5283},
	author = {Adams BR and Gee EK and Back PJ and Rogers CW}
}
@article {3672,
	title = {Live weight and bone growth from birth to 15 months of age in pure-bred and cross-bred Jersey and Friesian heifers},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {81},
	year = {2021},
	month = {01/2022},
	pages = {45-50},
	address = {Online},
	abstract = {
Live weight and liveweight gain of dairy heifers has been described in New Zealand and overseas, however, the change in stature and pattern of proximal and distal bone growth has, to date, received little attention. This study describes the proportional changes in stature with live weight, in a cohort of commercial dairy heifers (Holstein-Friesian, Jersey, and Holstein-Friesian-Jersey crossbred) from birth to 15 months of age. Comparisons of height, length, girth, and distal and proximal forelimb length (stature) revealed that at the same live weight, these parameters differed among breeds (P<0.05), however, the magnitude of the differences among breeds was consistently less than 1 cm. As heifer live weight increased, the contribution of the distal limb to increases in height decreased, which is consistent with knowledge that physeal closure in cattle occurs earlier in distal limb bones, such as the metacarpus, than in proximal limb bones, such as the humerus. In addition, the understanding of proximal and distal growth in cattle identifies when heifers are most susceptible to growth checks.

Keywords: bone; stature; fracture; dairy heifer},
	issn = {1176-5283},
	author = {Gibson MJ and Rogers CW and Hickson RE and Dittmer KE and Back PJ}
}
@article {3672,
	title = {Seasonal variation in pasture mass offered was not associated with changes in live weight, or body condition score, in three cohorts of horses},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {81},
	year = {2021},
	month = {01/2022},
	pages = {16-21},
	address = {Online},
	abstract = {Many New Zealand equine owners/stud managers rely on body condition to adjust feed supply for weight management, rather than objective weigh scales. This cohort observational study examined the inter-relationship of pasture supply with monthly BCS and live weight (LW) in three groups (n = 7, 8, 9) of grazing-horses of median 6/9 BCS (range 4-8). Dry-matter (DM) intake was estimated from weekly pasture mass (using rising-plate meter), monthly pasture cuts, and fortnightly LW records. Total pasture DM at the start of grazing ranged from 559 to 3511 kg DM/ha, and grazed lawns (nutritive areas) ranged from 364 to 2601 kg DM/ha. Total estimated DM offered (including hay when offered) ranged from 1.46 to 26.37 kg DM/horse/day (0.3\% to 5.3\% of horses LW). Within-horse maximum monthly gains and losses were 8\% LW and -13\% LW respectively. Median monthly BCS change was 0/9 (range -2/9 to 1/9). There was no significant association between monthly changes in LW and BCS, indicating BCS may lack the sensitivity to manage weight. During periods of reduced DMI (below estimated maintenance) there were no significant decreases in LW or BCS. These data implied that the horses may have altered transit time to improve the relative digestibility of the limited feed on offer.

Keywords: horse; weight; body condition score; pasture; intake},
	issn = {1176-5283},
	author = {Adams BR and Gee EK and Back PJ and Rogers CW}
}
@article {3672,
	title = {Effect of breed and paddock activity on bone mass and strength in three beef cattle breeds},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {80},
	year = {2020},
	month = {09/2020},
	pages = {29-33},
	address = {Online},
	abstract = {There are obvious phenotypic differences among beef cattle breeds, but, to date, there are limited data on the effect of breed
and pasture-based management systems on the bone mass and strength of the distal limb bone (metacarpals). The left 3rd/4th
metacarpal bones were collected from a cohort of Angus (AA) (n= 17), Angus {\texttimes} Friesian (AF) (n=13), and Angus {\texttimes} Jersey (AJ)
(n=13) cows aged nine years at slaughter. Prior to slaughter the cohort had been intensively monitored as part of longevity- and
GPS-based paddock-activity trials. Measures of metacarpal bone mass and strength were assessed using peripheral quantitative
computed tomography (pQCT) scanning at the mid-diaphysis after slaughter. Locomotion parameters, based on GPS data when
grazing, were collected when four and five years old. The AA and AF cows had significantly greater slaughter weight than AJ
(598{\textpm}14 vs 586{\textpm}18 vs 514{\textpm}17 kg, P<0.01 respectively). AA cows had lower wither height than AF and AJ (1288{\textpm}6 vs 1311{\textpm}8 vs
1269{\textpm}7 mm, P<0.01) and shorter metacarpal bone length (198{\textpm}2, vs 207{\textpm}2 vs 210{\textpm}2 mm, P<0.05). At the mid-diaphyseal site,
AF and AJ cows had greater bone mineral density (BMD)v than did AA cows (977{\textpm}8 vs 1018{\textpm}9 vs 1019{\textpm}9 mg/cm3, respectively,
P<0.001), but had less cross-sectional area (882{\textpm}16 vs 816{\textpm}18 vs 731{\textpm}18 g/cm3, P<0.05 respectively). Across all breeds, there
was a negative relationship of slaughter weight with BMDv. No significant relationships were found between distance walked on
moderate and steep terrain (GPS data) and the pQCT measures. Breed influenced the size and structure of the metacarpal bone,
which altered the material properties (pQCT) measured. The limited amount of high-strain-rate exercise in these cattle may explain
the lack of association between locomotion data and measures of bone mass and strength.

Keywords: bovine; bone; GPS; locomotion; beef},
	issn = {1176-5283},
	author = {Bijen L and Gibson MJ and Back PJ and Hickson RE and van Knegsel A and Rogers CW}
}
@article {3672,
	title = {The management of Standardbred breeding stock on commercial properties},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {80},
	year = {2020},
	month = {09/2020},
	pages = {84-89},
	address = {Online},
	abstract = {This paper describes the on-farm pasture management of Standardbred broodmares on commercial breeding farms in New Zealand
using data collected from three studies. The pasture on offer was typically ryegrass (70\% (IQR 50-70), clover (15\% (IQR 15-22),
and fescue (12\% IQR 6-22). Other species present included cocksfoot and plantain (10\% on one farm). Weed content was low at
5\% (IQR 4-8). During winter, on two farms mares were break-fed on crops of kale, standing oats and Italian ryegrass. Through the
year there was limited variation in the nutritive composition of the pasture with a DM of 17{\textpm}0.3\%, ME of 11{\textpm}0.1 MJ/kg DM and
crude protein of 23{\textpm}0.5\%. Horses were managed using a semi-set-stocked pattern (1.7 mares/ha; 2.6 weanlings/ha). Pasture DM
on offer for mares ranged from 1700-2500 kg DM/ha and 2500-3000 kg DM/ha for weanlings, which were also offered ~1.5 kg/
day (as fed) of pre-mixed concentrates. To manage pasture quality and minimise the establishment of lawns and roughs, paddocks
on all farms were harrowed and cross-grazed with sheep or cattle. The management system described, while similar to that of
Thoroughbreds, differs with the offering of crops to mares during winter and a higher BCS of mares.

Keywords: horse; pasture; Standardbred; management; mare},
	issn = {1176-5283},
	author = {Rogers CW and Herbst A and Langhans K and Stone R and Hirst R and Gee EK and Back PJ}
}
@article {3672,
	title = {Miniature horses in New Zealand: demographics and feeding management},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {80},
	year = {2020},
	month = {09/2020},
	pages = {1-7},
	type = {1-7},
	address = {Online},
	abstract = {An online survey on demographics and feeding management of Miniature horses in New Zealand was conducted using the
Qualtrics Survey Software. There were 232 valid responses from respondents who kept 1183 Miniature horses, representing ~  1/3rd
of the New Zealand Miniature horse population. Miniature horses were kept for leisure and companionship (56\%), competition
(35\%) and for breeding (7\%). The majority (79\%) of Miniature horses were kept at pasture on low (< 1000 kg DM/ha) to moderate
(~ 2000 kg DM/ha) pasture masses across seasons. Pasture access was more commonly restricted by respondents during spring
(60\%), summer (60\%), and autumn (55\%) than in winter (43\%). Most respondents (87\%) practiced pasture-restriction strategies
such as strip grazing, use of a paddock with little grass, and stabling/yarding. Respondents indicated the mode daily number of
hours of stabling was 7-12 hours (n=57/195, 29\%). The median stocking density was 10 horses/ha, (~1100 kg live weight/ha).
The stocking density appeared high, however, on a live weight basis, it was comparable to the reported values in other classes of
equine livestock.},
	issn = {1176-5283},
	author = {Goh SY and Gee EK and Thomas DG and Back PJ and Rogers CW}
}
@article {3672,
	title = {Association of bacterial contamination of colostrum with passive immunity and growth rates in dairy heifer calves},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {149-152},
	address = {Palmerston North},
	abstract = {Failure of passive transfer of immunity in calves is associated with poor-quality colostrum, determined by Immunoglobulin G (IgG) concentration. Another quality problem of colostrum is bacterial contamination, which can impair IgG absorption by the calf. Thirty-five samples from daily pooled first-milking colostrum collected over a period of six weeks were tested for IgG concentration and bacterial contamination. Seventeen of 35 first-milking colostrum samples (49\%) had bacterial counts above a 100,000 CFU/ml threshold. Twenty-nine of the 35 pooled colostrum samples were fed to 63 newborn heifer calves, of which 12 (41\%) had bacterial loads above 100,000 CFU/ml and were fed to 36 calves. Only eight samples (28\%) had Brix values >22\% and five samples (17\%) fed to nine calves met the criteria of low bacterial load and high Brix (>22\%). Twelve of the 63 calves (19\%) had serum IgG concentrations <10 mg/ml so were classified as having failure of passive transfer, of which 10 of these calves were offered colostrum with high bacterial counts. However, there was no association of level of bacterial contamination with subsequent growth. There were no differences in serum IgG concentrations of calves which were fed colostrum that exceeded the quality threshold and those that were not. Calves with greater serum IgG concentrations grew faster (P<0.05). },
	issn = {1176-5283},
	author = {Back PJ and Hickson RE and Sneddon NW and Coleman LW and Laven RA}
}
@article {3672,
	title = {Can bone measures of the bovine metacarpus predict humeral bone structure?},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {8-12},
	address = {Palmerston North},
	abstract = {Peak bone mass in cattle is influenced by factors prior to puberty and insufficient peak bone mass prior to the first lactation predisposes heifers to the risk of spontaneous humeral fractures. At post-mortem examination, affected heifers present with osteoporosis (reduced periosteal circumference and reduced cortical wall thickness). Due to its location, there is no cost-effective way to scan the humerus in the live animal. However, the metacarpal bones (MC3/MC4) are straightforward to scan in a live anaesthetised animal. The aim of this experiment was to determine if the metacarpal could be used to predict bone mass and material properties of the humerus. The left humerus and metacarpal bones were obtained from 57 cattle aged six weeks to eight years. Bones were scanned at the mid-diaphysis using peripheral quantitative computed tomography (pQCT), to obtain measures of bone mass and material properties (strength). Strong positive relationships were observed (R2=0.89 - 0.98, P<0.0001) for pQCT measurements of bone mass and strength. Thus, the metacarpus is a good predictor of bone content and material properties of the humerus across cattle of differing age and maturity. },
	issn = {1176-5283},
	author = {Gibson MJ and Rogers CW and Dittmer K and Hickson RE and Pettigrew EJ and Back PJ}
}
@article {3672,
	title = {Deterministic modelling of nitrogen utilisation by horses managed under pasture-based, intensive and semi-intensive systems with different levels of pasture intake.},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {1-7},
	address = {Palmerston North},
	abstract = {There are limited data on the average nitrogen (N) intake and N loss for the different classes of equine livestock, and the different equine production systems within New Zealand.  Using a deterministic model, the total nitrogen excreted, and nitrogen partitioned into animal requirements, urine and faeces were estimated based on the crude protein requirement, digestible crude protein intake, and crude protein excreted in urine and faeces.  Separate models were generated for five different livestock classes managed within three different production systems (commercial breeding farm, sport horse and racehorse). Overall, the N in diet (\%), the modelled daily N intake and N losses varied with the percentage of pasture in the diet.  The faecal N loss remained consistent (20-25\%) across diets and horse classes whereas urinary N loss increased with daily N intake and percentage of pasture in the diet. Total N loss per day was estimated to be 0.18, 0.28, and 0.48 g N/kg body weight in racehorse, sport horse and Thoroughbred mares respectively.  The N excretion per unit weight from young horses, racehorses and sport horses were substantially lower than that reported for ruminants. Therefore, horse-specific data should be used when modelling farm-level nitrogen excretion.},
	issn = {1176-5283},
	author = {Chin YY and Back PJ and Gee EK and Rogers CW}
}
@article {3672,
	title = {Growth and milk production of dairy heifers born to two-year-old or mixed-age dams},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {135-139},
	address = {Palmerston North},
	abstract = {Keeping replacement heifers that were the progeny of primiparous cows mated by artificial insemination, enhances rates of genetic gain. Heifers that were the progeny of primiparous cows were lighter at birth and grew at a slower rate to first calving compared with heifers born to multiparous dams. Heifers that were heavier before first calving produced more milk than did lighter heifers. This study aimed to determine if there were liveweight (LWT) or milk-production disadvantages for heifers born from primiparous compared with multiparous dams. Data comprised of LWT records from 189,936 New Zealand dairy heifers. Dams were allocated to four groups according to their age: two (2yo; n=13,717), three (3yo; n=39,258), four to eight (4-8yo; n=120,859) and nine years old or greater (>=9yo; n=16,102). Heifers born to 2yo dams were lighter (P<0.01) from three to 21 months of age than heifers born to 3yo and 4-8yo dams. The progeny of 2yo and 3yo dams produced similar milksolids yields during their first lactation (304.9{\textpm}1.6 and 304.1{\textpm}1.5 kg, respectively), but more (P<0.01) than that of 4-8yo dams (302.4{\textpm}1.5) and >=9yo dams (P<0.001; 297.8{\textpm}1.6 kg). Heifers born to 2yo dams were lighter but produced more milk than heifers from older dams.},
	issn = {1176-5283},
	author = {Handcock RC and Lopez-villalobos N and Back PJ and Hickson RE and McNaughton LR}
}
@article {3672,
	title = {Livestock and pasture management on commercial Thoroughbred breeding farms: implications for estimating nitrogen loss},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {65-70},
	address = {Palmerston North},
	abstract = {Published data on livestock and pasture management on Thoroughbred breeding stud farms were collated to model and estimate farm-level variables required to estimate nitrogen leaching. On commercial farms, stocking density doubled during the breeding season (August {\textendash} December). The effective stocking density increased with farm scale (number of resident mares) but decreased with farm size (total effective area). Therefore, farm nitrogen output may fluctuate seasonally and will be influenced by farm size and scale. Farm size and scale independently affected the stocking and grazing management (i.e., paddock rotation interval) for the different equine stock classes (empty, pregnant, mares with foals). Stocking and grazing management influenced the pasture available and subsequently, the grazing behaviour as determined by the difference between pasture mass of lawns and roughs. The difference between pasture mass of lawns and roughs was reduced with increasing stocking density and decreasing pasture availability, and increased under conditions of high stocking density (>2 mares/ha) and low pasture availability (<400 kg DM/ha/horse). Modification of grazing behaviour could affect the nitrogen-leaching potential by modifying the size of manure-deposition area and the N-loading rate on urine and dung patches. The complex relationship between farm, horse and management factors needs to be included when estimating nitrogen leached from equine properties.},
	issn = {1176-5283},
	author = {Chin YY and Back PJ and Gee EK and Rogers CW}
}
@article {3672,
	title = {Milk production and rebreeding performance of mixed-aged dairy cows mated to Angus or Hereford bulls},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {144-148},
	address = {Palmerston North},
	abstract = {Approximately 72\% of New Zealand dairy cows are artificially mated to generate replacement heifers. There is an opportunity to mate the remaining dairy cows to beef bulls, generating a calf that has value as a beef-cross-dairy animal. Angus and Hereford are the predominant beef breeds in New Zealand, with Hereford the most common beef breed used in the dairy industry. The aim of this experiment was to determine whether there was a difference in milk production and rebreeding performance of mixed-aged dairy cows producing a calf sired by an Angus or Hereford bull, and if calf birth weight influenced these parameters. Cows were artificially bred to Angus or Hereford bulls. Service sire-breed had no effect on milk production in early lactation. Cows producing Angus-sired calves had a 2.4 kg greater 253-day protein yield (P<0.05) than did cows producing Hereford-sired calves, however, there was no effect of calf sire-breed on the 253-day yields of milk, fat and milksolids. The in-calf rate and inter-calving interval did not differ between service sire-breed. There was no effect of calf birth weight on milk production, in-calf rate or inter-calving interval. The results of this experiment suggest that there are no negative effects associated with artificially breeding cows to Angus compared to Hereford bulls. },
	issn = {1176-5283},
	author = {Coleman LW and Back PJ and Blair HT and Lopez-villalobos N and Hickson RE}
}
@article {3672,
	title = {Using leafy turnip to maintain growth rates of dairy heifers during summer},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {108-111},
	address = {Palmerston North},
	abstract = {In New Zealand, growth rates of dairy heifers can be restricted during late summer/early autumn due to inadequate pasture production and quality, which may delay puberty and compromise lactational performance, and, ultimately reduce their longevity in the herd and overall farm profits. The aim of this experiment was to determine the effect of feeding leafy turnip as an alternative summer forage to ryegrass-based pasture on the growth rate of heifers. Forty-five heifer calves aged six months were assigned to one of two treatment groups: (1) ryegrass-based pasture and (2) leafy turnip and were fed a combination of these feeds during summer/early autumn. Calves fed a greater proportion of leafy turnip were heavier (235.6 {\textpm} 3.8kg, P<0.05) and had greater average daily gain (0.74 {\textpm} 0.01 kg/day, P<0.05) than calves fed a greater proportion of pasture (218 {\textpm} 3.9 kg and 0.59 {\textpm} 0.01 kg/day), primarily due to pasture supply being restricted during the latter part of the experiment. The greater liveweight advantage from feeding leafy turnip remained for two months. Leafy turnip could be considered as an option to maintain growth rates of dairy heifers when pasture supply is restricted.},
	issn = {1176-5283},
	author = {YC Fan and Purchas GS and Hickson RE and Back PJ}
}
@article {3672,
	title = {Assessment of vigour in early life of dairy calves in New Zealand},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {78},
	year = {2018},
	month = {07/2018},
	pages = {161-164},
	address = {Lincoln},
	abstract = {Vigour of dairy calves in the first few days of life may be a relevant predictor of subsequent performance in an artificial-rearing
system. This experiment aimed to evaluate two scoring systems to determine whether they detected variation in beef-sired calves
born in the New Zealand pastoral dairy system. The scoring systems included a vigour score devised for housed dairy calves in
Canada which had a range of physical and physiological parameters assessed, and a drinking score assessed at the feeder in the first
few days of life (1=calf does not attempt to suck on feeder, 5=calf drinks vigorously for the whole feed). Calves generally scored
highly (17-21 out of a possible 22 points) on the vigour score and meconium staining, head/tongue swelling, movement and heart
rate showed little to no variation among calves. The drinking score showed that few calves scored in the low categories, and the
scoring system may be improved by creating greater separation within the higher categories. Angus-cross calves were more likely
to have a higher drinking score than Hereford-cross calves, and light or young calves were more likely to have low drinking scores.},
	issn = {1176-5283},
	author = {Gillingham J and Coleman LW and Back PJ and Mueller K and Hickson RE}
}
@article {3672,
	title = {Characteristics of the grazing and farm management of broodmares on commercial Thoroughbred stud farms during spring},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {78},
	year = {2018},
	month = {07/2018},
	pages = {88-91},
	address = {Lincoln},
	abstract = {Thoroughbred broodmares in New Zealand are at greater odds of exposure to Leptospira than racehorses, possibly as a result
of aspects of the on-farm pasture-based management. To identify biologically plausible risk factors cohorts of broodmares were
prospectively followed on four Thoroughbred stud farms for a five-week period during the 2017-2018 season. Up to three cohorts
of mares within each group of mares identified at the start of the study as empty (not in foal), in-foal, or mares having just foaled
(with foal at foot) were followed on each farm and measurements made of pasture dry matter (DM) on offer, paddock location,
mare cohort structure and farm management. The farm with stallions had a greater number of changes in mare cohort membership
(2 (1-2) vs. 0 (0-1), P=0.001). The total pasture DM on offer was least for empty mares compared to in-foal mares, and mares with
foals at foot (1483 (1157-2380) vs. 2070 (1499-2534) vs. 2299 (1390-3196) kg DM/ha, P=0.009). Pregnant mares had the greatest
stocking density 4 (2 -6) mares/ha, due to use of small foaling paddocks. The low pasture DM on offer and high stocking rate for
empty mares may provide a mechanism for exposure to environmental sources of Leptospira.},
	issn = {1176-5283},
	author = {Bengtsson J and Rogers CW and Back PJ and Emanuelson U and Roca J and Gee EK and Bolwell CF}
}
@article {3672,
	title = {Pasture use and management in commercial equine production systems},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {78},
	year = {2018},
	month = {07/2018},
	pages = {40-44},
	address = {Lincoln},
	abstract = {Despite a perceived reliance of horses on pasture there are limited data on efficiency of pasture utilisation in equine production
systems. The unique equine behaviour characteristics of highly selective browsing, combined with faecal avoidance, provide
distinct grazing management challenges compared to those of ruminants. Data reported here show that faecal avoidance results in
the establishment of lawns and roughs (overgrazed and poorly grazed areas, respectively) with it estimated that only 70\% of the
total pasture DM/ha on offer is utilised by horses. During spring, lawns contained more grass (74\% vs 53\%) and clover (5\% vs 3\%)
and less weeds (2\% vs. 11\%) and dead matter (19\% vs. 33\%) than did roughs. Weanlings will start to graze roughs once the lawns
are <1500 kg DM/ha. Roughs, however, will not be grazed within 1 m of a faecal pile. This translates to a lower pasture utilisation
rate in weanlings and the biased grazing pattern means estimates of total pasture DM over-estimate the true available pasture DM.
The relative proportion of pasture in lawns and roughs changes during grazing and prevents the application of a simple correction
factor to estimate available DM. Broodmares had greater rates of pasture utilisation and less bias for consumption of pasture in
areas of roughs than did weanlings.},
	issn = {1176-5283},
	author = {Rogers CW and Gee EK and Back PJ and van Zon S and Hirst RL and Pomroy WE}
}
@conference {3672,
	title = {Brief Communication: Managing liveweight gain of Holstein-Friesian, Jersey and Holstein- Friesian-Jersey crossbred heifer calves},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {77},
	year = {2017},
	month = {06/2017},
	pages = {69-71},
	address = {Rotorua},
	abstract = {Large numbers of replacement heifers are not meeting target live weights in New Zealand (McNaughton \& Lopdell 2012; Handcock et al. 2016) which has implications for future milk production, fertility and subsequent longevity in the herd (Van Amburgh \& Tikofsky 2001; McNaughton \& Lopdell 2013). Undergrown heifers can lead to an overall decline in a herd{\textquoteright}s reproductive performance and milk production (McNaughton \& Lopdell 2012). McNaughton and Lopdell (2013) reported that for every 1\% increase in the percentage of live weight attained, heifers produced approximately 23 litres of extra milk during their first two lactations. As such, heifer growth, particularly post-weaning growth, has been identified as an area requiring greater attention from farmers to improve cow performance. There are established breed liveweight targets as well as liveweight targets based on an individual animals genetic potential and the growth of individual animals and groups can be monitored using programmes such as Livestock Improvement Corporation{\textquoteright}s MINDA Weights{\texttrademark} herd-recording software. However, while growth targets are commonly used, in many cases, being {\textquoteleft}on-target{\textquoteright} is based on a mob average, resulting in a proportion of animals below target live weight....},
	issn = {1176-5283},
	author = {Back PJ and Hickson RE and Sneddon NW and Coleman LW and Laven RA}
}
@conference {3672,
	title = {The percentage of spring-calving carryover cows in New Zealand dairy herds and their milk production, compared to heifers, age-matched and lactation-matched non-carryover cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {77},
	year = {2017},
	month = {06/2017},
	pages = {3-7},
	address = {Rotorua},
	abstract = {Non-pregnant cows are generally culled from dairy herds and replaced with heifers. Alternatively, non-pregnant cows can be dried-off at the end of lactation, retained for one year (carried over), before being mated and returned to a milking herd in the following year. The aim of this study was to estimate the percentage of spring-calving carryover cows in New Zealand dairy herds and to compare their milk production with that of heifers, lactation-matched and age-matched non-carryover cows. Results showed that 2.5\% of spring-calving cows had experienced a previous carryover period. The majority (43\%) of carryover cows had failed to conceive during their first lactation. Most (69\%) dairy herds contained less than 5\% carryover cows and 17\% had zero carryover cows. Second-lactation carryover cows produced 4778.1{\textpm}6.3 L milk, 228.7{\textpm}0.3 kg fat, 182.0{\textpm}0.2 kg protein, and had a somatic cell score (SCS) of 6.31{\textpm}0.01, which was greater (P<0.001) than the milk production of heifers that produced 3514.5{\textpm}5.9 L milk, 168.3{\textpm}0.3 kg fat, 134.0{\textpm}0.2 kg protein, and had a SCS of 5.89{\textpm}0.01. Carryover cow milk production was also greater (P<0.001) than that of lactation-matched and age-matched non-carryover groups. The results of this study will aid on-farm culling decisions.},
	issn = {1176-5283},
	author = {Gardner RR and Back PJ and Lopez-Villalobos N and McNaughton LR}
}
@conference {3672,
	title = {BRIEF COMMUNICATION: Do different grazing strategies affect pre-weaning calf growth rates?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {76},
	year = {2016},
	month = {07/2016},
	pages = {119-121},
	address = {Adelaide},
	abstract = {Rearing replacement heifer calves is a labour-intensive
and expensive component of dairy systems (Drackley
2008). Large numbers of replacement heifers are not
meeting target live weights in New Zealand (McNaughton
\& Lopdell 2012) which has implications for future milk
production, fertility and subsequent longevity in the herd
(Van Amburgh \& Tikofsky 2001).
This paper reports results from the second year of a
long-term experiment being conducted at Massey University
that examines the impact of colostral status and liveweight
gain of heifer calves fed different diets on subsequent milk
production, fertility and longevity in the herd. Previous
work (Cardoso et al. 2015) demonstrated no difference in
pre-weaning liveweight gain of calves fed different levels
of milk. The calves in that study ate surprisingly little meal.
It was surmised that the exposure to frequent shifts onto
fresh pasture stimulated intake of pasture, and removed
the advantage of feeding calves higher levels of milk and
supplementation with meal. Anecdotally, many calves
when removed from rearing sheds to pasture are kept on the
same paddocks as they are not a high priority for pasture
allocation. Therefore, the aim of this experiment was
further collection of colostral and Brix data as described by
Coleman et al. (2015), and to compare pre-weaning growth
rates of calves that are continually offered fresh pasture to
those that are set stocked.},
	issn = {1176-5283},
	author = {Back PJ and Hickson RE and van Bouwel K and de Cock H and Verdurmen J and Sneddon NW and Laven RA}
}
@conference {3672,
	title = {Grazing behaviour and species selection of heifer calves fed different forages.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {76},
	year = {2016},
	month = {07/2016},
	pages = {126-131},
	address = {Adelaide},
	abstract = {<p>The aim of this experiment was to determine whether there was a difference in the behaviour of calves grazing different forages. Weaned dairy heifer calves (n = 64) were assigned to two different forage feeding treatments: ryegrass pasture and a clover-herb mix. Behavioural observations were recorded every 10 minutes over a 72 h period. Behaviours recorded were standing, walking, lying or sitting, grazing, ruminating, drinking/grooming, playing and various combinations of these. Calves grazing pasture spent more time lying and ruminating compared to calves grazing the clover-herb mix (34.6\% vs 16.7\%), and less time standing and grazing (17.2\% vs 32.2\%). Calves were less active from late evening and early morning and more likely to be ruminating earlier in the day and grazing later in the day. Plant selection (measured as plant disappearance rate) was determined in calves grazing the clover-herb mix. Red clover had the highest disappearance rate on all days compared to other species (P\&lt;0.05). Plantain, chicory and white clover eaten on day one did not differ in proportions eaten, but by day three less red clover and chicory remained compared to plantain and white clover (P\&lt;0.05).</p>
},
	issn = {1176-5283},
	author = {Back PJ and Hickson RE and Lilly VM and Coleman LW and Sneddon NW and Laven RA}
}
@conference {3672,
	title = {The influence of age and breed of cow on colostrum indicators of suckled beef calves},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {76},
	year = {2016},
	month = {07/2016},
	pages = {163-168},
	address = {Adelaide},
	abstract = {Rearing a calf to weaning is a key measure of performance in a beef breeding cow herd. Adequate intake of colostral antibodies
by the calf in the first few hours of life is important for passive transfer of immunity, and so is beneficial for calf survival. This
experiment aimed to examine the role of udder conformation, maternal age and breed-cross on the colostral status of suckled
calves. Udder conformation of Angus, Angus-cross-Friesian, Angus-cross-Jersey and Angus-cross-Kiwicross cows was scored
according to Animal Evaluation Limited and BreedPlan standards, and colostral status of calves was determined based on gamma
glutamyltransferase activity, immunoglobulin G and total protein concentrations at 24-48 hours of age. Udder conformation was
similar (P>0.05) among breed-crosses except Angus cows had looser front udder attachment, lower rear udder attachment and less
desirable udders overall than Angus-cross-dairy cows (P<0.05). Most udder conformation scores did not affect colostral status of
calves. The exception was teat placement score, for which more outward-pointing teats were associated with improved colostrum
status of calves (P<0.05). Survival to weaning was greater for calves with adequate compared with inadequate colostral status
(P<0.001).},
	issn = {1176-5283},
	author = {Hickson RE and Back PJ and Martin NP and Kenyon PR and Morris ST}
}
@conference {3672,
	title = {BRIEF COMMUNICATION: Composition of milk sampled from beef-cross-dairy cows unaccustomed to milking.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {260-262},
	address = {Dunedin},
	abstract = { },
	issn = {1176-5283},
	author = {Hickson RE and Back PJ and Coleman LW and Lopez-Villalobos N and Kenyon PR and Morris ST}
}
@conference {3672,
	title = {BRIEF COMMUNICATION: Do high-milk diets affect the growth rate of heifers prior to weaning?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {263-265},
	address = {Dunedin},
	abstract = { },
	issn = {1176-5283},
	author = {Cardoso DS and Hickson RE and Laven RA and Coleman LW and Back PJ}
}
@conference {3672,
	title = {Colostral immunoglobulin G as a predictor for serum immunoglobulin G concentration in dairy calves},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {3-8},
	address = {Dunedin},
	abstract = { Feeding newborn calves high-quality colostrum is of well-recognised importance as calves that do not receive an adequate
concentration of immunoglobulin-G (IgG) have an increased risk of morbidity and mortality. This experiment aimed to characterise
IgG concentrations in colostrum from the first milking in New Zealand dairy cows, examine IgG status of calves, and to evaluate
the use of a refractometer for estimating quality of colostrum in terms of IgG concentration. Heifer calves entered the calf shed at
0-24 hours of age and were fed pooled first-milking colostrum within eight hours of entering the shed. Blood samples were taken
the following morning. Cows were individually milked and samples from individual and pooled colostrum were analysed. IgG
concentration of serum and colostrum samples were determined by turbidimetric immunoassay. IgG concentration was adequate
according to commercial reference ranges in 70.1\% of individual colostrum, 80.0\% of pooled colostrum and 82.5\% of calf serum
samples. There was no relationship between calf serum and IgG concentration in dam or pooled colostrum. The refractometer was
a good predictor of IgG concentration in serum (r=0.64, P<0.0001) and colostrum both in dam (r=0.87, P<0.0001) and pooled
(r=0.81, P<0.0001) samples. The relationship between IgG concentration and refractometer reading indicates that it could be a
useful on-farm tool.},
	issn = {1176-5283},
	author = {Coleman LW and Hickson RE and Amoore J and Laven RA and Back PJ}
}
@conference {3672,
	title = {The use of herb mix and lucerne to increase growth rates of dairy heifers},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {132-135},
	address = {Dunedin},
	abstract = { Approximately 53\% of 6-month-old dairy heifers in New Zealand do not meet liveweight targets, partially due to inadequate growth rates in their first summer. The aim of this experiment was to determine the effect of feeding forage crops on the growth
rate of dairy heifers over this critical period. Sixty six-month-old dairy heifers grazed one of three treatments: pasture, lucerne
or a mixed-herb crop for a 63-day period. Both lucerne- and crop-fed heifers had similar (P>0.05) average daily liveweight gain
(0.80 {\textpm} 0.02 and 0.75 {\textpm} 0.02 kg/day, respectively) and were greater (P<0.05) than those of pasture-fed heifers (0.53 {\textpm} 0.02 kg/
day). Lucerne-fed heifers had a greater (P<0.05) increase in body length (18.4 {\textpm} 1.3 cm) than heifers fed pasture (14.7 {\textpm} 1.2 cm).
Heifers fed lucerne had higher (P<0.05) concentrations of urea in plasma (4.9 {\textpm} 0.1 mmol/L) compared with heifers fed crop (4.1
{\textpm} 0.1 mmol/L), which had greater (P<0.05) concentrations of urea in plasma than heifers fed pasture (2.5 {\textpm} 0.1 mmol/L). Feeding a
mixed-herb crop or lucerne during the summer period resulted in higher growth rates of dairy heifer calves compared with feeding
them pasture.},
	issn = {1176-5283},
	author = {Handcock RC and Hickson RE and Back PJ}
}
@conference {3677,
	title = {Growth rates of dairy heifers fed alternative feeds },
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {74},
	year = {2014},
	month = {06/2014},
	pages = {29-34},
	address = {Napier},
	abstract = {Dairy heifers need to achieve average daily gains (ADG) that allow them to reach liveweight targets. The aim of this experiment was to measure the effects of grazing 6-month-old dairy heifers on alternative feeds, over the summer period. Sixty 6-month-old Friesian-Jersey crossbred heifers were assigned to one of three treatments (pasture (P), conserved forages (C) or lucerne (L), with all treatments receiving supplementary meal. For the 6-week experiment, feed allowance was based on liveweight gain required to meet liveweight targets. Heifers were weighed at 0, 3 and 6 weeks of the treatment period. Wither height, crown-to-rump length and girth circumference were measured at the start and end of the experiment. L heifers had a greater (P<0.05) average daily gain (1.22 + 0.03 kg/day) than P heifers (0.57 + 0.03 kg/day), and C heifers were intermediate (0.78 + 0.03 kg/day). L and C heifers had a greater (P<0.01) increase in wither height (0.15 + 0.01 cm/day and 0.14 + 0.01 cm/day respectively) than P heifers (0.11 + 0.01 cm/day). L heifers had the greatest (P<0.05) increase in girth circumference (0.30 + 0.02 cm/day, compared with P and C heifers: 0.22 + 0.02 cm/day and 0.16 + 0.02 cm/day respectively). A combined diet of lucerne and meal during drought conditions increased ADG resulting in a greater proportion of heifers reaching liveweight targets.},
	issn = {1176-5283},
	author = {de Clifford RP and Hickson RE and Martin NP and Back PJ}
}
@conference {79027,
	title = {Effect of resolving a sub-clinical uterine infection on plasma and follicular fluid steroid concentrations in early lactation dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {72},
	year = {2012},
	month = {Jan},
	pages = {231-235},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Sub-clinical endometritis (scEndo) in early lactation affects ovarian follicle dynamics, delays a return to cyclicity, with changes in plasma and follicular fluid (FF) amino acid concentrations around the time of rebreeding. This study examined the effect of resolving scEndo in early lactation on plasma and FF oestrogen, progestagen, androgen and corticosteroid concentrations at the time of rebreeding in 46 dairy cattle. On D42 postpartum, cows were classified as having scEndo, clean or having resolved scEndo cased on uterine cytology on D21 of > 18\% polymorphonuclear (PMN) cells amongst uterine nucleated cells. On D42 and D63 follicular and plasma samples were collected and steroid concentrations analysed. On D21 and D42, 35\% and 7\% of cows respectively were classified as having scEndo, with 81\% of scEndo cows having self-resolved the infection by D42. In those cows that resolved scEndo, none of the plasma or FF steroid concentrations changed between D42 and D63, except for plasma progesterone (P = 0.08). Using a low (4\%PMN) threshold to classify scEndo did not identify any significant changes in steroid concentrations. In contrast to previously described changes in plasma and FF amino acid concentrations, there were no significant effects on steroid concentrations when cows self-resolved a sub-clinical uterine infection.},
	issn = {1176-5283},
	author = {Lopdell TJ and Berg MC and Green MP and Back PJ}
}
@conference {75925,
	title = {Effect of sub-clinical uterine infection on plasma amino acid concentrations in early lactation dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {71},
	year = {2011},
	month = {Jan},
	pages = {291-295},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Invercargill},
	abstract = {This study examined the effect of sub-clinical endometritis (scEndo) in early lactation on plasma amino acid (AA) concentrations of dairy cattle (n = 46). On D21 and D42 postpartum cows were classified as having scEndo or Clean based on uterine cytology; >18\% polymorphonuclear (PMN) cells amongst uterine nucleated cells. On D21 and D42, 35\% and 7\% of cows respectively were classified as having scEndo, with a large proportion of scEndo cows having self-resolved the infection by D42. Plasma serine concentrations were higher (P <0.03) in scEndo compared to Clean cows irrespective of day postpartum. Independent of uterine status, three AA altered (P <0.05) in concentration between D21 and D42. The effect of change in uterine status from D21 to D42 resulted in decreased (P =0.05) concentrations of three AA in cows that resolved infection. The use of a lower cut-off to define scEndo (4\% vs 18\%PMN) identified four AA, instead of three AA at 18\% that differed over time. Thus, during the early postpartum period, the concentrations of a number of AA change (P <0.05) irrespective of uterine health. However, scEndo is associated with an increase in plasma serine and a decrease in the concentration of several AA when a uterine infection is resolved.},
	issn = {1176-5283},
	author = {Lopdell T and Berg MC and Green MP and Back PJ}
}
@conference {75860,
	title = {Presidential Address 2010 - What will it take to feed the world and what is the role of New Zealand animal production in this?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {71},
	year = {2011},
	month = {Jan},
	pages = {1-2},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Invercargill},
	abstract = {A recent United Nation{\textquoteright}s report stated that the world{\textquoteright}s growing population will require twice as much food in 40 years time. What opportunities and challenges does this present for agricultural product producing countries? How will researchers meet the challenge of feeding a world population that is estimated to grow to 9 billion people by 2050? This is not an area that... Continued},
	issn = {1176-5283},
	author = {Back PJ}
}
@conference {75926,
	title = {Sub-clinical uterine infection is associated with altered amino acid concentrations of follicular fluid in early lactation dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {71},
	year = {2011},
	month = {Jan},
	pages = {296-300},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Invercargill},
	abstract = {The effect of sub-clinical endometritis (scEndo) in early lactation on follicular amino acid (AA) concentrations was determined. On D21 and D42 postpartum cows were classified as having scEndo or Clean based on uterine cytology; >18\% polymorphonuclear (PMN) cells amongst uterine nucleated cells. On D21 and D42, 35\% and 7\% of cows respectively were classified as having scEndo, with a large proportion of scEndo cows having self-resolved the infection by D42. Follicular histidine (P = 0.04), as well as alanine, aspartate and serine concentrations (P <0.1) were higher in scEndo compared with Clean cows. The effect of change in uterine status from D21 to D42 resulted in increased (P <0.1) follicular glutamate, ornithine and valine concentrations in cows that resolved infection. Correlation coefficients were determined to test the relationship between plasma and follicular AA concentrations. A greater number of AA in Resolved cows showed no relationship between plasma and follicular concentrations compared to Clean cows. Thus, scEndo is associated with an increase in follicular histidine and an increase in the concentration of several AA when a uterine infection is resolved. This study demonstrates that scEndo may be responsible for long-term alterations in follicular AA concentrations that could potentially result in altered oocyte viability.},
	issn = {1176-5283},
	author = {Back PJ and Lopdell T and Berg MC and Green MP}
}
@conference {69530,
	title = {Differences in follicle dynamics and the importance of luteal support in young and old cohorts of genetically identical dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {70},
	year = {2010},
	month = {Jun},
	pages = {303-305},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {There has been a documented decrease in fertility in the modern dairy cow selected for milk yield (Pryce et al.,2004). This emphasises the need for farmers in a seasonal grass-based system such as that in New Zealand to correctly manage herd genetics in conjunction with nutrition to optimise cow reproductive performance. The question remains however as to the relative influence and interdependence of these two factors in establishing a pregnancy, as an optimal size for the ovulatory follicle is directly related to successful conception and pregnancy (Perry et al., 2005).},
	issn = {1176-5283},
	author = {Green MP and Back PJ and Berg MC}
}
@conference {60936,
	title = {Effects of sub-clinical endometritis on ovarian follicular activity in postpartum dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {69},
	year = {2009},
	month = {Jun},
	pages = {32-36},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The effects of sub-clinical endometritis (scEndo) on ovarian follicular activity in pasture-fed dairy cows were determined. The uterine-health status of lactating dairy cows (n = 169) was assessed on day (D) 21 ({\textpm} 3 days) postpartum by Metricheck. In a sub-population (n = 47; 32 clean, 15 scEndo), Metricheck assessment was repeated on D42 and uterine cytology undertaken on D21 and D42 [scEndo = polymorphicnuclear (PMN) cells >18\%]. Follicular activity was assessed by ultrasound on D42 and D63. Metricheck evaluation revealed that the proportion of cows with scEndo was 15/169 (8.9\%) and 4/47 (8.5\%) on D21 and D42 respectively. Irrespective of the method used to determine scEndo, dominant (P <0.001) but not subordinate (P >0.1) follicles were larger and grew faster on D63 than on D42. Based on the D21 Metricheck but not the \%PMN classification, dominant follicles of scEndo cows were larger and grew faster (P = 0.02) than those in clean cows. No overall effect of uterine status was found on the subordinate follicles, although these tended (P = 0.06) to be larger on D63 than on D42 but only in clean cows. Thus early postpartum scEndo appears to modulate the subsequent size of the dominant follicle. However, it remains to be determined whether this affects the subsequent fertility of these cows. },
	issn = {1176-5283},
	author = {Back PJ and Ledgard AM and Beaumont S and Berg MC and Peterson AJ and McNatty KP and Green MP}
}
@conference {60937,
	title = {Prevalence and identification of systemic markers of sub-clinical endometritis in postpartum dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {69},
	year = {2009},
	month = {Jun},
	pages = {37-42},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The prevalence of sub-clinical endometritis (scEndo) and identification of serum markers of scEndo was investigated in pasture-fed, postpartum dairy cows. Mixed age lactating dairy cows (n = 169) were examined for uterine health status on day (D) 21 postpartum ({\textpm} 3 days) by Metricheck classification. On D42 in a subpopulation (n = 47; 32 clean, 15 scEndo) Metricheck assessment was repeated and uterine cytology undertaken on D21 and D42 [scEndo = polymorphicnuclear (PMN) cells >18\%]. Uterine bacteriology, as well as haematological, biochemical and milk parameters were also measured. The prevalence of scEndo was 15/169 (8.9\%) and 4/47 (8.5\%) cows on D21 and D42 respectively. A high incidence of self-resolving scEndo (11/15, 73\%) was revealed. Numerous species of pathogenic bacteria were isolated from both scEndo and clean cows. Despite the uterine infection being sub-clinical, systemic markers were detectable as on D21 and D42 haematological and biochemical parameters differed. Irrespective of the scEndo classification method used, the mean blood neutrophil concentration was higher (P <0.05) and plasma albumin lower (<0.05) in scEndo cows compared to clean cows. Milk fat and protein \% also differed (P <0.05) between scEndo and clean cows. The monitoring in early lactation of these markers could aid identification of scEndo, thereby preventing potentially detrimental effects on subsequent fertility. },
	issn = {1176-5283},
	author = {Green MP and Ledgard AM and Berg MC and Peterson AJ and Back PJ}
}
@conference {41778,
	title = {Indole and skatole as markers for nitrogen utilisation in dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {68},
	year = {2008},
	month = {Jan},
	pages = {23-26},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Brisbane, Australia},
	abstract = {Indole and skatole are products of amino acid degradation in the rumen which could be useful to monitor protein utilisation in grazing ruminants. Two groups ("1970s" strain and "current" strain) of mixed age Holstein Friesian cows were housed indoors and fed cut pasture for 21 days. Concentrations of indole and skatole in milk fat and of milk urea nitrogen were determined. No significant differences were observed between strains of cow for indole and skatole concentration in milk fat, but they were different (P<0.01) between sampling dates. Both indole and skatole had moderate positive (r ~0.50) correlation with the rumen degradable protein (RDP) balance, whilst skatole had a weaker (r ~0.30) correlation with crude protein intake, metabolisable protein supply and RDP supply. Indole and skatole concentrations in milk fat were more closely correlated to the estimated RDP balance in the rumen than milk urea. A large proportion of individual animal variation in milk metabolites remains unaccounted for by protein intake, and may relate to individual differences in detoxification and elimination of indole and skatole. },
	issn = {1176-5283},
	author = {Pacheco D and Lane GA and Fraser K and MacDonald KA and Back PJ}
}
@conference {41764,
	title = {Breed and heterosis effects for milk protein composition estimated in two stages of lactation in New Zealand dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {399-402},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {The aim of this study was to estimate breed and heterosis effects for milk protein composition found within the two main breeds farmed in New Zealand, Holstein-Friesian (HF) and Jersey (J). Groups of 20 F, 20 J and 20 HFxJ crossbred cows (3 years and older) calved at pasture between July and September 2003 and were monitored throughout the 2003/04 season. Breed and heterosis effects were estimated for daily yields of milk, crude protein, true protein and casein and concentrations of crude protein, true protein, casein, α-casein,  β-casein,  κ-casein,  α-lactalbumin and  β-lactoglobulin, bovine serum albumin (BSA) and immunoglobulin G (IgG). Breed effects were significant (P<0.05) for all traits except for β-lactoglobulin, BSA and IgG. Compared to J cows, HF cows had significantly (P<0.05) higher daily yields of milk (+5.32 kg), crude protein (+0.13 kg), true protein (+0.11 kg) and casein (+0.10 kg) but significantly (P<0.05) lower concentrations of crude protein (-0.50 g/kg), true protein (-0.51 g/kg), casein (-0.45 g/kg), α-casein (-3.77 g/kg), β-casein (-2.08 g/kg), κ-casein (-1.74 g/kg) and α-lactalbumin (-0.14 g/kg). Estimates of heterosis effects for concentration of milk proteins were negative but only significant for κ-casein (-0.60 g/kg). These results show that that the individual protein fractions of milk are affected by breed but crossbreeding has no beneficial effect on milk protein composition.},
	issn = {1176-5283},
	author = {Back PJ and Lopez-Villalobos N}
}
@conference {41738,
	title = {Evaluation of a model that estimates insulin sensitivity in dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {261-265},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {Glucose challenge data was used to model parametersdescribing the dynamics of the glucose-insulin system such as glucose effectiveness (SG), acute insulin response to glucose (AIRg) and insulin sensitivity (SI) in dairy cows. The relationship of these parameterswith post-partum anovulatory interval (PPAI) was also determined. Twenty-five HF cows of New Zealand (NZ; n=13) and Overseas (OS; n=12) origin, were fed either pasture (n=12) or a total mixed ration (TMR; n=13) in a 2x2 factorial design. At two weeks postpartum, they were challenged intravenously with 300 mg of glucose/kg live weight. There was no effect of diet on SG(P=0.302), SI(P=0.17) or AIRg(P=0.093) despite TMR cows of both genotypes having higher values. There was no effect of genotype on SG(P=0.234), SI(P=0.742) or AIRg(P=0.385). Correlations of these parameters with PPAI were not statistically significant: SI  (r 2=0.087, P=0.310), SG(r 2 = 0.001,  P=0.962) and AIRg(r 2 =0.036, P=0.320). Use of this model demonstrated that insulin response parameters  were not closely associated with PPAI.},
	issn = {1176-5283},
	author = {Back PJ and Boston RC and Palliser CC and Kolver ES and Chagas LM}
}
@conference {41934,
	title = {Effect of cow genotype and feed allowance on milk composition},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {397-402},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {The effect of strain of Holstein-Friesian and level of feed allowance on milk composition, individual milk proteins, and minerals was examined in a seasonal calving pastoral dairying system. The trial included two high genetic merit strains of either North American (OS90) or NZ (NZ90) genetics, and one strain representing NZ 1970{\textquoteright}s genetics (NZ70). Each strain was farmed under systems designed to provide total feed allowances of 4.5 to 7.0 t DM/cow/year. Milk composition was affected by strain of cow and by feed allowance. Strain of cow influenced crude protein (P<0.05), true protein (P<0.01) and casein (P<0.01) concentrations, with the NZ90 and OS90 strains having higher concentrations than the NZ70 strain. Increased feed allowance resulted in increased crude protein (P<0.05), true protein (P<0.05) and casein (P<0.05) concentrations. Strain, but not increased feed allowance affected the protein:fat ratio, with the OS90 strain having a higher ratio (P<0.05) than the NZ strains. Strain altered concentrations of {\'a}-casein (P<0.05), with NZ90 having the highest concentrations and NZ70 the lowest concentrations. No consistent effect of strain or feed allowance was determined on whey proteins except for {\^a}-lactoglobulin (P<0.027), where the OS90 strain had higher concentrations than the NZ strains. No consistent effect of strain or increasing feed allowance was seen on milk mineral concentrations. These results demonstrate that different selection and breeding policies have influenced major milk components which may influence milk processing and product characteristics. },
	issn = {1176-5283},
	author = {Turner S-A and MacDonald KA and Back PJ and Thomson NA}
}
@conference {41681,
	title = {Effect of dairy cow breed on the metabolic adaptation to lactation},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {390-396},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Three breeds (20 Friesian, 20 Jersey and 20 Jersey/Friesian crossbred multiparous cows) were used to determine the effect of breed on indicators of metabolic status and the post partum anovulatory interval (PPAI). Effect of breed on circulating concentrations of metabolites and hormones, liver mRNA levels and PPAI was established. Weekly blood samples were taken for the first 6 weeks of lactation. Liver biopsy samples were taken from a sub-sample of cows of each breed between 23-33 days post partum, to determine levels of expression of T-GHR, GHR-1A and IGF-1 receptors using RT-PCR. Milk progesterone analysis was used to determine PPAI. There was a significant breed effect on circulating concentrations of {\^a}-hydroxy butyrate (P<0.01), non-esterfied fatty acids (P<0.001), triacylglycerols (P<0.001) and leptin (P<0.01), with Jersey cows having higher concentrations of these hormones and metabolites than Friesian or crossbred cows. Despite the concentration differences between breeds, only leptin showed a significant difference (P<0.01) in the rate of change in concentration across time between the breeds. Jersey cows were observed to have shorter PPAI (34 vs 42 and 44 days for Friesian and crossbred cows respectively: SED 6 days) but this was not statistically significant (P=0.18). There was no difference in the expression of mRNA levels of TGHR, GHR-1A and IGF-1 receptors in the liver. It appears that grazing Jersey cows have a different fat metabolism, which affects the regulation of circulating leptin concentrations and this may have contributed to their apparent ability to return to cyclicity earlier. },
	issn = {1176-5283},
	author = {Back PJ and Meier S and Barnett CME and Cursons RT and Thomson NA}
}
@conference {41536,
	title = {Exploiting cow genotype to increase milk value through production of minor milk components},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {53-58},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Milk value could be increased on-farm by supplying milk with enhanced concentrations of minor compounds that have bioactive properties. Compounds of interest in this study were the whey proteins lactoferrin (Lf) and lactoperioxidase (LP), and milk fatty acids; particularly conjugated linoleic acid (CLA) and omega-3 fatty acids. Mixed genotype cows (20 Friesian, 20 Jersey and 20 crossbred) were sampled to determine the effect of cow genotype and age on Lf concentration, Lf yield and LP activity at 4 times during the season. In milk fat, concentration of CLA and omega-3 fatty acids were determined twice during the season. Cow genotype had no effect on Lf concentration but age did (P < 0.002), with 4-year and older cows producing greater concentrations in milk than 3 year old cows. For harvesting Lf, Friesian cows would be the most profitable, with the greatest Lf yields, particularly in mid-late lactation. The highest LP activity levels throughout lactation were demonstrated in Jersey milk. In milk fat, Friesian cows produced milk of a putatively healthier profile, with greater concentrations of unsaturated fatty acids, CLA and omega-3 fatty acids.
Key words: milk value; cow genotype; lactoferrin; lactoperoxidase; conjugated linoleic acid; omega-3 fatty acids. },
	issn = {1176-5283},
	author = {Back PJ and Thomson NA}
}
@conference {41494,
	title = {Effects of a commercial feed containing conjugated linoleic acid on the production of milk components and the value of milk},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {150-154},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {This study was to evaluate changes in cow productivity and milk value from feeding a rumen-protected form of CLA to pasture-fed dairy cows in early lactation. 30 New Zealand Friesian dairy cows were randomly assigned at calving to either 0g (control) or 120g/d of a commercial rumen protected feed containing CLA from 4 days post-calving for 16 weeks. Milk yield and composition data was collected weekly. A simulation model was used to calculate yield of dairy products based on accumulated yields of milk and its components per cow during the experimental period. Feeding CLA reduced (P<0.001) fat concentration (3.1\% vs 4.2\%) and increased (P<0.05) milk yield (2688 kg vs 2423 kg), and protein yield (89.9 kg vs 81.2 kg). The effect of CLA on milk fat concentration was reflected in the yield of dairy products and milk value. Milk from cows fed CLA had less (P<0.01) excess of fat sold as butter (48.4 vs 69.4 kg butter). The value of milk ($/kg MS) was higher (P<0.001) from cows fed CLA than from control cows at 2002/03 prices ($3.87 vs $3.66) and when butter price was low ($3.56 vs $3.24). },
	issn = {1176-5283},
	author = {Back PJ and Lopez-Villalobos N}
}
@conference {41400,
	title = {The effects of insulin on the milk production of pasture-fed Jersey cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {35-39},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {The aim of this experiment was to determine the effects of insulin on milk protein production in lactating, pasturefed dairy cows. Five lactating rumen-fistulated Jersey cows were subjected to a hyperinsulinaemic euglycaemic clamp (HEC) with and without an abomasal infusion of casein (310g/d) in a two period cross-over design experiment. The HEC significantly reduced milk yield in the control cows compared to casein-infused cows (9.9 {\textpm} 0.5 vs 13.2 {\textpm} 0.5 kg/d, P<0.001). Milk protein yield was significantly higher in the casein-infused cows compared to the control cows (482 {\textpm} 16 vs 421 {\textpm} 16 g/d, P<0.05). The HEC significantly reduced milk protein yield in the control cows compared to casein-infused cows (311 {\textpm} 16 vs 459 {\textpm} 16 g/d, P<0.001). The use of the HEC technique in pasture-fed cows did not result in the milk protein response reported in concentrate-fed cows. },
	issn = {1176-5283},
	author = {Back PJ and MacKenzie DDS and Davis SR and Harris PM and Lee J}
}
@conference {41271,
	title = {Effects of insulin on amino acid uptake by the mammary gland of the pasture-fed lactating ruminant},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {144-147},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Twelve lactating ewes housed indoors were allocated to one of two treatment groups (hyperinsulinaemic euglycaemic clamp (HEC) or control) in a randomised block design experiment. Mammary amino acid uptake from plasma and utilisation for milk protein synthesis was measured during the fourth day of the HEC using the arterio-venous concentration difference (A-V) technique. There was no change in milk protein output during the HEC (P>0.05). The HEC induced a significant decrease in arterial concentrations of all essential amino acids (EAA) except for histidine and an increase in the extraction efficiency of isoleucine (HEC, 61 {\textpm} 3\% vs. control, 52 {\textpm} 3\%, P<0.05) and leucine (HEC, 64 {\textpm} 3\% vs. control, 53 {\textpm} 3\%, P<0.05). There was no significant change in extraction efficiency of other EAA or mammary blood flow. The ratio of amino acid uptake from plasma to output in milk protein suggested deficits in uptake for some EAA in both treatments, especially histidine. These results indicate that the mammary gland can adapt to a changing arterial supply of amino acids to maintain milk protein output by increasing extraction efficiency and/or a greater reliance on amino acids supplied by erythrocytes and/or plasma peptides. },
	issn = {1176-5283},
	author = {Back PJ and Davis SR and MacKenzie DDS and Harris PM and Roy NC and Lee J}
}
@conference {41073,
	title = {Lack of effect of short term chromium supplementation in lactating Jersey cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {58-61},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The responses of dairy cattle to chromium (Cr) supplementation reported in the literature suggest that it has the potential to reduce the incidence of both mastitis and ketosis. The effect of Cr supplementation of pasture fed dairy cows in early lactation was studied. Ten lactating Jersey cows fitted with rumen fistula were infused with either Cr-yeast (n=4), casein (n=3) or buffer only (controls; n=3) directly into the abomasum. All cows were subjected to a hyperinsulinaemic euglycaemic clamp. Preliminary results show that there was no effect of Cr supplementation on milk yield, cortisol and b-hydroxy butyrate concentrations and somatic cell counts. },
	issn = {1176-5283},
	author = {Back PJ and Lee J and MacKenzie DDS and Davis SR and Harris PM}
}
@conference {41029,
	title = {The effects of Insulin-nutrient supply interactions on ewe lactation},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {205-208},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Six lactating abomasally cannulated ewes were subjected to a hyperinsulinemic euglycemic clamp with or without casein supplementation in a two period crossover design experiment. There was a significant response in milk (1169 {\textpm} 46 g/d vs 952 {\textpm} 46 g/d, P<0.001) and milk protein (66.4 g/d {\textpm} 2.7 g/d vs 54.2 g/d {\textpm} 2.7 g/d P<0.006), yield from casein supplemented ewes. There was no overall effect of the clamp on milk and milk protein yield, while the interaction was also non-significant. However, there was a significant reduction in feed intake (P<0.001) as the clamp continued, which may have compromised milk and milk protein response. There was also a significant period effect across all the measured parameters, which could also be a stage of lactation effect, due to the rapid decline of milk production during ewe lactation. In this study, in contrast to concentrate-fed cows, the utilisation of this technique did not increase milk protein yield in pasture fed lactating ewes. },
	issn = {1176-5283},
	author = {Back PJ and MacKenzie DDS and Davis SR and Harris PM}
}
