Effect of birthweight on survival in triplet-born lambs

摘要: Lambing percentage is the main contributor to higher profit on New Zealand sheep farms and has increased from 98% in 1960 124% 2006. As ewe litter size increases so does proportion of triplet-born lambs consequently preweaning mortality rate. The purpose this study was investigate effect birthweight (BWT) survival within among litters. Data a total 594 triplet crossbreed born mixed-age ewes analysed. For statistical analysis, were allocated according their BWT, then three BWT groups (light, medium heavy). following parameters calculated: (TBWT), TBWT for each lamb (PBWT = BWT/TBWT), coefficient variation average daily gain birth weaning. rate light, heavy 56, 40 28%, respectively, lightest 3.2 times more likely die than heaviest lamb. In light group, as decreased (P = 0.006), did not influence (P = 0.88) group there trend associated with (P = 0.10). negative relationship between PBWT identical (P < 0.0001). became non-significant when fitted same model. This means that, lambs, influenced by itself, but its littermates. It can be calculated that 4-kg 24% chance surviving 16 kg, 60% 12 kg an 87% 8 kg. concluded reducing litter, or specifically managing at birth, will increase competitive ability and, therefore, decrease overall further improve farm profitability.