@conference {3672,
	title = {Field investigation of the iodine status of farms in the North Island of New Zealand},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {77},
	year = {2017},
	month = {06/2017},
	pages = {77-81},
	address = {Rotorua},
	abstract = {Over a 10-year period 104 farms in the North Island were attended on a consultancy basis, and of these, 29 farms were identified as having clinical signs associated with iodine deficiency (high peri-natal calf mortality, poor conception rate and/or low pregnancy rate). Mean pasture iodine concentrations (n=24) were 0.28 mg/kg (SD=0.16) ({\textquoteleft}adequate{\textquoteright} range: 0.40-0.80 mg/kg). Mean animal plasma inorganic iodine (PII) concentrations (n=17) were 40.6 μg/L (SD=16.28) ({\textquoteleft}inadequate{\textquoteright} range <45 μg/L). Marginally low iodine status (20-45 μg/L) was present in 13.5\% of farms (14 of 104). The overall average deficit for the farms with low pasture iodine (n=19) was calculated to be 3.0 mg iodine per cow per day. Corrective treatment was computed for each farm and made pri-marily through weekly addition of iodine to the drinking water. Following iodine supplementation, mean animal PII was 60.8 μg/L (SD=19.50), a 50\% increase over initial values. For individual cattle, there was a significant reduction in the proportion (73.5\% to 23.5\%) whose PII was marginally low (P=0.001). Clinical responses in livestock were monitored, and on the iodine supplemented farms there was some evidence for a reduction in peri-natal calf mortality and an increase in conception rates, but the amount of data was limited. Iodine supplementation was seen to contribute to an overall increase in pregnancy rates on ten farms (from 79.4\% to 91.1\%). It is concluded that iodine deficiency is common in North Island pasture-based livestock farms, that it is responsive to dietary supplementation, and that supplementation may be associated with improved reproductive performance.},
	issn = {1176-5283},
	author = {Anderson PD and McGhie DON and Parkinson TJ}
}
@conference {89265,
	title = {Effect of dam size and nutrition during pregnancy on fetal testicular development in sheep},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {73},
	year = {2013},
	month = {Jan},
	pages = {41-44},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {<p>In male sheep, testicular development is almost complete at birth. Testicular cells start to differentiate as early as Day (D) 27 of gestation followed by steroidogenesis and the activation of associated enzyme systems (Rhind 2004). Sertoli cells are present at around D34 and replication continues postnatally (Hochereau-de Reviers et\&nbsp; al. 1987). Seminiferous cords that will develop into tubules appear between D35 and D40 (Sweeney et al. 1997; Rhind et al. 2001). By D70 the rete testis is organised in the centre of testis (Sweeney et al. 1997) and between D35 and D85 the GnRH neuronal system develops in the hypothalamus (Caldani et al. 1995). Testicular gonocytes are typically observed between birth and 25 days after birth, and then progressively differentiate into spermatogonia up to 70 days after birth (Sharpe et al. 2003).</p>
},
	issn = {1176-5283},
	author = {Asmad K and Kenyon PR and Parkinson TJ and Pain SJ and Lopez-Villalobos N and Blair HT}
}
@conference {75874,
	title = {BRIEF COMMUNICATION: The effects of dam nutrition during pregnancy on the growth of male offspring},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {71},
	year = {2011},
	month = {Jan},
	pages = {59-61},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Invercargill},
	abstract = {During pregnancy, nutritional status of the ewe is crucial because of its potential effect on fetal development, subsequent lamb survival and reproduction post-birth (Rhind et al., 2001). Manipulation of the progress of fetal development can affect the structure and physiology of adult offspring through the process of fetal programming (Barker et al., 1993). Epidemiological data... Continued },
	issn = {1176-5283},
	author = {Asmad K and Paten AM and Loureiro MFP and Kenyon PR and Pain SJ and Parkinson TJ and Pomroy WE and Scott I and Blair HT}
}
@conference {60931,
	title = {Maternal environment as a regulator of birth weight and body dimensions of newborn lambs},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {69},
	year = {2009},
	month = {Jun},
	pages = {10-14},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The present research study was undertaken to investigate the effect of maternal uterine environment on birth weight of lambs. Embryos were transferred within, and reciprocally between, Suffolk and Cheviot sheep to establish four groups of pregnancies: Suffolk in Suffolk (SinS; Large control), Suffolk in Cheviot (SinC; Restricted uterine environment) Cheviot in Suffolk (CinS; Luxurious uterine environment) and Cheviot in Cheviot (CinC; Small control). Birth weight and other morphological characteristics of lambs such as head width, head length, crown-rump length, heart girth, fore leg length, hind leg length and femur length were recorded within 24 h of birth. Various placental parameters were also recorded at lambing. Birth weight of SinC lambs (5.04 {\textpm} 0.20 kg) was significantly (P <0.05) lower than SinS lambs (5.93 {\textpm} 0.19 kg). All of the body dimensions were also significantly (P <0.05) reduced in SinC compared with SinS lambs. However, neither birth weight nor other morphological parameters were significantly different (P >0.05) between CinC and CinS lambs. Among placental parameters, cotyledon number was significantly (P <0.05) lower in CinS (57.48 {\textpm} 6.27) than SinS group (74.17 {\textpm} 5.88). These results indicate that a restricted maternal uterine environment affects birth weight probably via alteration to placental characteristics. },
	issn = {1176-5283},
	author = {Sharma RK and Jenkinson CMC and Blair HT and Kenyon PR and Parkinson TJ}
}
@conference {41746,
	title = {Effects of experimentally induced and treated Streptococcus uberis mastitis early in the dry period on production in the subsequent lactation},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {303-306},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {The effect of experimentally induced clinical mastitis in the early dry period (EDPCM) upon the milk production in the subsequent lactation was examined. Animals with low somatic cell counts at herd test (n=165) were experimentally exposed to Streptococcus uberis in their early dry period in an efficacy study of two external teat sealants. Animals that developed EDPCM after challenge (n=127) were treated with an antibiotic after observation of clinical mastitis. Total lactation yields of milk, fat, protein and milk solids were analysed with respect to treatment group (fixed effect) and the covariables: calving week (linear), parity (linear and quadratic) and proportion of Holstein-Friesian genes (linear). For animals that suffered EDPCM and those that did not, there was no difference in production (milk yield; 5126 vs. 5010 litres, fat yield; 267 vs. 264 kg, protein yield; 182 vs. 179 kg). It was concluded that promptly treated EDPCM due to S uberis, did not affect production in the subsequent lactation.},
	issn = {1176-5283},
	author = {Petrovski KR and Williamson NB and Fernandez C and Grinberg A and Lopez-Villalobos N and Parkinson TJ}
}
@conference {41988,
	title = {Iodine deficiency in dairy cattle},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {248-254},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {Clinical signs of iodine deficiency (e.g. non-visible oestrus, low first service conception rate, stillbirths), plus low (<45 nmol/L) serum thyroxine (T4) concentrations were observed in dairy cows from 12 farms in the Manawatu. Goitre, as determined by diffuse thyroid hyperplasia,plus significantly (p<0.05) increased thyroid size, weight and thyroid:bodyweight ratio, was found in 16\% (6 of 38) of stillborn calves from these farms. Goitre was present in calves from 42\% (5 of 12) of the herds. One of these farms was chosen to investigate temporal changes in concentrations of the thyroid hormones, thyroxine (T4) and tri-iodothyronine (T3), as an indicator of iodine status, and to attempt to determine the optimum time for sampling. Blood samples were collected from a cohort of animals from the herd (20 representative animals from 400 cows) 8 times over a 12 month period, for measurement of total serum iodine (TSI), T3 and T4 concentrations in both individual cows and pooled (10 cows) samples. T4 was maximal in June (58.6 nmol/L) and lowest (39.2 nmol/L) in October (P<0.05). Between November and Augusts meanTSI varied (NS) from 31 {\textpm} 9 to 47 {\textpm} 9 {\textmu}g/L, but was significantly (P<0.01) higher in October (91 {\textpm} 16 {\textmu}g/L). T4 concentrations were(P<0.05) related (r = 0.35) to TSI between November and August (7/8 blood samplings), but were widely divergent (r = 0.08) in October. Concentrations of T3 were unrelated to TSI (r= 0.07). In pooled samples, concentrations of TSI, but not T3 or T4, were closely related to the mean concentrations in individual animals. An iodine-response study was also carried out on the same herd. Half the herd (200 of 400) were given (6 mL i/m) iodised oil (Flexidine, Bomac) before mating and before calving. The pregnancy rate in anoestrous cows treated with iodine was 13.9\% higher than in untreated cows. It was concluded that T4 (individual animals) or TSI (pools of 10 cows) give equivalent information about the iodine status of a herd, except in the post calving period. However, the reference range needs to be validated by further response trials.},
	issn = {1176-5283},
	author = {Anderson PD and Dalir-Naghadeh B and Parkinson TJ}
}
@conference {41465,
	title = {Can mating ewes on condensed tannin-containing forages be used to reduce lamb mortality between birth and weaning?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {30-33},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Five grazing experiments are described where ewes were fed forages which are likely to increase the absorption of essential amino acids (EAA) for periods of 63-70 days, immediately before and during mating, relative to control ewes mated on grass based pastures. The legume Lotus corniculatus (Birdsfoot trefoil CV Grassland Goldie) was fed in two experiments and supplements of willow or poplar forage trees were given to ewes mated on low quality drought pasture in three experiments. Both L. corniculatus and the forage trees contained condensed tannins (CT) and in addition the crude protein content of the forage trees (166 g/kg DM) was much higher than that of drought pasture (122 g/kg DM).
Mating on L. corniculatus and supplementing with forage trees consistently increased lambing percentage. Lamb mortality between birth and weaning was significantly reduced (P<0.05) by mating on L. corniculatus in one experiment and by feeding forage trees during mating in one experiment. Similar trends of smaller magnitude were evident in the other experiments and did not attain statistical significance.
Hypotheses of how feeding these forages during mating may have reduced post-natal lamb mortality are advanced and methods of testing the hypotheses are suggested. },
	issn = {1176-5283},
	author = {Barry TN and Parkinson TJ and Ramirez-Restrepo CA and McWilliam EL and Lopez-Villalobos N}
}
@conference {41426,
	title = {Development of a technique to evaluate the role of elevated maternal thyroid hormone concentrations in the birthweight response to mid-pregnancy shearing.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {149-151},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {Several studies have shown that lambs born to mid-pregnancy shorn ewes are heavier at birth than those born to unshorn ewes (Morris et al. 2000, Kenyon et al. 2002a,b) but, the mechanism responsible has not been identified. Morris et al. (2000) observed elevated maternal triiodothyronine (T3) concentrations over a 20-day period after shearing at mid-pregnancy in both single- and twin-bearing ewes and subsequently found an increased birthweight in the singletons. Symonds et al. (1989) also reported maternal T3 and T4 concentrations to be higher in pregnancy-shorn housed ewes although, an altered birthweight was not reported. },
	issn = {1176-5283},
	author = {Kenyon PR and Parkinson TJ and Revell DK and Morris ST and McCutcheon SN}
}
@conference {41425,
	title = {Metabolic changes in ewes shorn during mid-pregnancy},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {144-148},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {Previous work has shown that, under appropriate circumstances, mid-pregnancy shearing results in an increase of both the birth and weaning weights of multiple-born lambs. However, the physiological mechanisms for this response are poorly understood. This paper attempts to clarify the link between mid-pregnancy shearing and heavier lamb weights by investigating the metabolic changes that occur in ewes that are shorn in mid-pregnancy. Twenty-four twin-bearing ewes were assigned to one of two treatment groups; mid-pregnancy shorn (70 days after the mid-point of mating: P70) or unshorn. Groups were balanced for ewe age and weight. Blood samples were collected from all animals on days P53, P69, P81, P84, P90, P109 and P130, for measurement of concentrations of triiodothyronine (T3), thyroxine (T4), cortisol, glucose, non-esterified fatty acids (NEFA) and beta-hydroxybutyrate. Lamb birth weight, girth and crown-rump length (CRL) measurements were collected within 24 hrs of birth. Lambs were weighed at weaning. Mid-pregnancy shearing increased lamb birth weights and girths by 0.43 kg (P<0.05) and 2.18 cm (P<0.05) respectively although these differences were not significant once adjusted for date of birth. There was no effect on CRL. Plasma concentrations of T3 and T4 were significantly higher in mid-pregnancy-shorn ewes relative to unshorn ewes at both P81 (P<0.01) and P84 (P<0.01 and P<0.05 respectively) and T4 concentrations tended to be higher at P90 (P<0.10). There was a significant effect of shearing treatment at P81 on plasma NEFA concentrations (P<0.05). There were no significant post-shearing differences in mean cortisol, glucose or beta-hydroxybutyrate concentrations. The study proposes that the most likely mechanism by which mid-pregnancy results in higher lamb birth weights is by increasing maternal thyroid hormone concentrations, resulting in an increase in fat mobilisation causing increased NEFA concentrations in the maternal blood supply, which in turn improves placental nutrition and, thus, lamb birth weight. },
	issn = {1176-5283},
	author = {Sherlock RG and Kenyon PR and Morris ST and Parkinson TJ}
}
@conference {41410,
	title = {Postpartum anoestrous intervals and reproductive performance of three genotypes of Holstein-Friesian dairy cattle managed in a seasonal pasture-based dairy system.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {77-81},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {An extended postpartum anovulatory interval (PPAI) is the major form of infertility in New Zealand (NZ) dairy cattle. Recently, Holstein cows, originating from North American genetic strains (Overseas; OS), have been widely used in NZ. Worldwide, there is concern over an apparent decline in the fertility of Holstein-Friesian dairy cattle. This study determined whether differences existed in PPAI, BCS and parameters of reproductive performance between NZ and OS Holstein-Friesians. One hundred and forty-six records from 88 NZ animals of high genetic merit for milk production (NZH), 81 records from 48 NZ animals of low genetic merit (NZL), and 137 records from 88 OS high genetic merit animals that calved in Years 1 (all two-year-olds) and 2 (two- and three-year-olds) were included. Over both years PPAI in two-year-olds were significantly shorter in OS (20 days shorter) and NZL (12 days shorter) than in NZH animals (P<0.05). Body condition score at calving, and BCS loss from calving to four weeks postpartum were not different between strains. In Year 1 of the study significantly more NZH than NZL or OS 2-year-olds were treated for anoestrus prior to the start of mating (P=0.001). Other measures of reproductive performance did not differ significantly between strains. The differences in PPAI require further investigation. },
	issn = {1176-5283},
	author = {McNaughton LR and Verkerk GA and Parkinson TJ and MacDonald KA and Holmes CW}
}
@conference {41307,
	title = {Monitoring onset of puberty in three genetic strains of Holstein-Friesian dairy cattle},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {30-33},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {Live weight and age at puberty were determined in three strains of Holstein-Friesian dairy cattle in each of two consecutive years. The strains were overseas-origin high-breeding-worth genetics (OS), New Zealand-origin high-breeding-worth genetics (NZH), and New Zealand-origin low-breeding-worth genetics (NZL), similar to the New Zealand dairy cow of the 1970s. Onset of puberty was monitored by weekly measurement of progesterone in a total of 271 heifers. Animals were considered to have attained puberty when plasma progesterone concentrations were greater than 2ng/ml in two out of three consecutive samples. Live weight at puberty differed between the strains (OS > NZH > NZL; P<0.05) but not between years. Age at puberty was affected by strain in Year 1 (OS > NZH > NZL; P<0.01), but not in Year 2. The greater live weight required to attain puberty in OS genotype animals must be recognized in target live weights for rearing of heifers. },
	issn = {1176-5283},
	author = {McNaughton LR and Morgan SR and Gore P and Verkerk GA and Holmes CW and Parkinson TJ}
}
