@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}
}
@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 = {Comparison of health and reproductive treatments over three seasons for once-a-day and twice-a-day milking herds},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {77},
	year = {2017},
	month = {06/2017},
	pages = {211-215},
	address = {Rotorua},
	abstract = {Once-a-day (OAD) milking has been increasing in popularity in New Zealand, while housing cows is being advocated as one means of minimising environmental impacts of dairying. The present study aimed to investigate health treatments under four different farming systems: OAD, and three twice-a-day (TAD) systems (housed, standard and commercial). There were health records from 377 cows milked OAD and 878 cows milked TAD, over the dairy seasons 2013-14, 2014-15 and 2015-16. Data were analysed assuming binomial distributions for the dependent variables with a generalised linear model that included the effects of season, system (OAD, TAD systems), breed and lactation number. In 2014-15, cows milked OAD were treated less often for mas-titis than cows milked TAD (12\% and 25\% respectively; P<0.05). Cows milked OAD had fewer reproductive treatments compared to cows milked TAD (standard) in 2014-15 and 2015-16 (1\% vs 39\% and 2\% vs 40\% respectively; P<0.01). These results support the advice to farmers that milking OAD does not have a major impact on the risk of mastitis but may provide benefits in terms of reproductive performance. In addition, cows milked TAD (housed) had 13\% of the cows treated for lameness compared to 7\% of cows milked TAD (standard) (P<0.01). },
	issn = {1176-5283},
	author = {Van Der Spek P and Sneddon NW and Lopez-Villalobos N and Donaghy DJ and Laven RA and Mueller KR and Amoore J and Doohan H}
}
@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 = {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 = {Using polymerase chain reaction to identify Streptococcus uberis in bovine milk: how does it compare with bacterial culture?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {20-23},
	address = {Dunedin},
	abstract = { Rapid identification of the pathogen responsible for an intramammary infection in a dairy cow can support herd management
decisions. Polymerase chain reaction (PCR) has become available to identify mastitis pathogens in milk, offering a rapid and
sensitive test. The performance of a commercial, real-time PCR assay was compared with traditional bacterial culture for the
identification of the most-frequent pathogen in New Zealand, Streptococcus uberis, during three stages of lactation. Aseptically
collected quarter-milk samples (n=6,848) were analysed by culture, and a subset (n=315) selected for PCR analysis based on S.
uberis infection status. Using culture as the reference test, PCR had a relative sensitivity of 89.0\%, and a specificity of 64.3\%
(kappa=0.49) for detecting S. uberis in milk collected at the first milking post-calving. The relative sensitivity and specificity
for samples collected in mid-late lactation were 89.3\% and 97.7\%, respectively, indicating a greater agreement between the two
tests later in lactation (kappa=0.88). Accurate diagnostic tests are necessary for mastitis management. In early lactation, when S.
uberis prevalence is high, bacterial culture should be used. The PCR assay tested in this study is most useful after the first month
of lactation.},
	issn = {1176-5283},
	author = {Steele NM and Williamson JH and Laven RA and Hillerton JE}
}
@conference {69512,
	title = {Measurement of sole thickness and distance to distal phalanx using a portable ultrasound machine},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {70},
	year = {2010},
	month = {Jun},
	pages = {240-242},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {Using a high specification ultrasound machine, with the ultrasound transducer applied to the sole surface, Kofler et al.(1999) were able to estimate sole and soft tissue thickness in claws from bovine cadavers. These ultrasound estimates were significantly correlated with measurements, made using mechanical callipers,of the same parameters in claws after sectioning. Moreover, Kofler et al.(1999) demonstrated that it was possible to image the internal structures of the bovine claw in the live animal and also reported the use of a portable ultrasound. They did however state that the images were of lower quality, due to the poorer resolution of the transducer, and were more difficult to obtain. In contrast, van Amstel et al.},
	issn = {1176-5283},
	author = {Laven LJ and Margerison JK and Laven RA}
}
