Does sward height grazed by ewes in mid- to late-pregnancy affect indices of colostrum intake by twin and triplet lambs?
OBJECTIVE
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.
Kenyon
P R
PR
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand. p.r.kenyon@massey.ac.nz
Stafford
K J
KJ
Morel
P C H
PC
Morris
S T
ST
D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling / Q000254:growth & development*; D003126:Colostrum; D005260:Female; D007774:Lactation / Q000502:physiology*; D008098:Litter Size; D008892:Milk / Q000737:chemistry*; D009751:Nutritional Requirements; D006109:Poaceae; D049590:Postpartum Period / Q000502:physiology; D011247:Pregnancy; D012756:Sheep / Q000378:metabolism* / Q000502:physiology