Does sward height grazed by ewes in mid- to late-pregnancy affect indices of colostrum intake by twin and triplet lambs?

Authors: Stafford KJ, Morel PCH, Kenyon PR, Morris ST
Publication: New Zealand Veterinary Journal, Volume 53, Issue 5, pp 336-339, Oct 2005
Publisher: Taylor and Francis

Animal type: Livestock, Production animal, Ruminant, Sheep
Subject Terms: Animal production/wastage, Bodyweight/liveweight/condition score, Milk, Diet/rations/food, Farm/farm management, Nutrition/metabolism, Management, Grazing, Growth/development, Mammary gland/udder, Mortality/morbidity, Pasture/crop, Pregnancy, Reproduction, Reproduction - female, Twinning/parity
Article class: Short Communication

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Abstract: AIMS: To determine if sward height grazed by ewes in mid- to late-pregnancy affects subsequent indices of colostrum intake by twin and triplet lambs, and the extent of the variation in colostrums intake between twin and triplet litter-mates.
METHODS: Blood samples were collected from 75 twin and 46 triplet litters, respectively, 24–36 h after birth. Samples were not collected from lambs that died before this age. Lambs were born to ewes which had grazed one of four sward heights (2, 4, 6 and 8 cm) during mid- to late-pregnancy. Serum samples were analysed for gamma-glutamyl transferase (GGT) activities and glucose concentrations. The number of lambs present at weaning was used to determine lamb survival rate.
RESULTS: GGT activities of lambs born to ewes that grazed swards 2 cm high were lower than those born to ewes that grazed swards 4 and 6 cm high (p=0.053 and p=0.037, respectively). Glucose concentrations were higher in twin than triplet lambs (p=0.003) and in lambs born to ewes grazed on swards 6 cm high than those born to ewes grazed on swards 2 cm high (p=0.033). These differences were not evident after correction for differences in birthweight. There was significant (p<0.001) variation within litter-mates for GGT activities and glucose concentrations in both twins and triplets. The blood constituent status of lambs that died before the 24–36 h collection period is not known. However, lambs which died after this period had significantly lower GGT activities (p=0.009) and glucose (p=0.010) concentrations at the time of sampling than those which survived.
CONCLUSIONS: Farmers should ensure twin- and triplet-bearing ewes in mid- to late-pregnancy are grazing at least 4 cm of herbage to ensure colostrum intake of lambs in the postpartum period is not adversely affected.
KEY WORDS: Sward height, triplet, twin, lambs, colostrum, gamma-glutamyl transferase, lamb birthweight, lamb survival

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