@conference {41702,
	title = {Calcium balance in mid and late pregnancy and vaginal prolapse},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {61-67},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {Given the hypothesis that Ca status may be implicated in bearings, the purpose of the research in 
experiment 1 was to observe Ca status in old twinewes in normal commercial conditions to determine 
whether an association exists, and in the second experiment to manipulate Ca status to determine its effects 
on the incidence of bearings. In experiment 1, Romney ewes, scanned as twin (n=12) or single (n=12) 
pregnant, on each of 7 farms were identified and sampled at approximately 60, 30 and 7 d before the onset of 
flock lambing. Whole flock bearing incidence was recorded. Eleven to 41\% of pregnant ewes from different 
farms had marginal serum Ca and Mg concentrations at 60 and 30 d before onset of lambing. No relationship 
was found between serum minerals and metabolite concentration and bearing incidence among farms. 
The objective of experiment 2 was to reduce bearings on farms with high historical incidences of bearings 
by increasing Ca loss in urine in mid-pregnancy (60 to30 d pre-lambing) followed by increasing Ca supply 
in late-pregnancy (30 to 0 d pre-lambing). Five farmers fed 100 twin pregnant ewes 35 g of anionic salts in 
300-500 g of supplemental pellets (DCAB -814 meq/kgDM) from 60 to 30 d before lambing. From 30 d 
these ewes were then injected with 4 ml of a long-acting vitamin D formulation (5 farms) while one farm 
also had an additional group supplemented with Ca (8g lime (ground calcium carbonate) /ewe) in an attempt 
to increase Ca availability. In addition, groups of ewes not treated withanionic salts were injected with 
vitamin D (2 farms) or supplemented with Ca (1 farm) from 30 d. Following consumption of anionic pellets 
in mid-pregnancy, the pH of the ewes{\textquoteright} urine was lower and urinary Ca:creatinine ratios were higher after 2 
(6.73 vs. 7.32, P<0.002; 0.47 vs. 0.16, P<0.003) and 4 weeks (6.26 vs.7.23, P<0.001; 0.58 vs. 0.14, P<0.003) 
of treatment. However, neither the feeding of anionic salts in mid-pregnancy nor the Ca or vitamin D 
supplements in late-pregnancy consistently changed Ca serum concentrations or bearing incidence. },
	issn = {1176-5283},
	author = {Litherland AJ and Knight TW and Lambert MG and Cook TG and McDougal DBO and Day A}
}
@conference {41955,
	title = {The effects of zeranol or zinc supplementation before lambing on the incidence of vaginal prolapse in twinning ewes},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {68-72},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {The objectives were to determine whether Zeranol (ZER) and its metabolites or pharmacological zinc levels could change the incidence of vaginal prolapse(bearings) in ewes. In the ZER experiment 100 twin pregnant ewes were controls, a further 50 ewes each received either two low (24 mg and then 12 mg) or two high (36 mg and then 24 mg) doses of zeranol (ZER) implants separated by a four-week interval with 65\% of treated ewes receiving an additional 12 mg implant at set stocking. Urine samples were collected from 12 ewes, twice weekly, bulked into three samples and analysed for Zearalenone (ZEN), ZER and creatinine. Two weeks after receiving an implant, the ZER:creatinine ratio increased from 2.6 in C ewes to 21, 30 and 36 and the ZEN ratio from 3.25 to 6.7, 10.8 and 14.7 following treatment with 12, 24 and 36 mg of ZER (P<0.01). One month after treatment the ZER and ZEN ratios had decreased but were still higher in treated than control ewes (ZER 3.6 vs.11, P<0.01; ZEN 1.2 vs.5.2, P<0.01). The bearing incidence was 3\%, 2\% and 2\% for control, low and high dose ZER respectively. In the second experiment 100 scanned twin or triplet pregnant ewes were administered with 72 g of zinc oxide (The Time Capsule {\textregistered}) as a ruminal bolus 4-6 weeks before lambing on four farms with historical high incidences of bearings. Pre-treatment and all control serum zinc concentrations were low (9.4 {\textpm}0.2 mmol/L) but not considered deficient. Zinc supplementation increased serum zinc concentrations to 21.5 mmol/L (P<0.001). Bearing incidence was higher (P<0.001) in zinc-treated (4\%) than in control ewes (1.9\%). In conclusion, bearings are not caused by ingestion of ZEN in late pregnancy. The role of zinc in bearings warrants further study.},
	issn = {1176-5283},
	author = {Litherland AJ and Knight TW and McDougall DBO and Cook TG and Sprosen J and Lambert MG}
}
