The effect of body condition score on lamb body weight and litter size in a flock of Chaal sheep

Body condition score of sheep depends on the amounts of muscle and fat tissues in horizontal and vertical lumbar vertebrae that show the obesity of live animal. This rating also controls body condition of ewe to detect physical changes and can modify farm management toward improving productive and reproductive traits and thus farm efficiency. The aim of this study was to investigate the effect of BCS of ewes on lamb body weight and litter size in Chaal sheep.
Body condition scores of 147 ewes with the age of one to six years old and body weight of 45 to 75 kg were used in a sheep farm located in Takestan County, Qazvin, Iran. Body condition scores of ewes were recorded at 10 to 12 days before mating. Ewes were divided based on BCS into five groups with an increment of one unit (1, 2, 3, 4 and 5). Body condition scores were measured by hand and feeling the muscle and fat tissues along the backbone (between the four last lumbar vertebrae of the spine and the last rib). Minitab 14 was used to estimate the effects of body condition scores on litter size and lamb body weights at birth, weaning and fifth months of age. General linear model and Logistic procedures were used for analyzing body weight traits and litter size, respectively.
Effects of sex and litter size were significant on lamb body weights and male and single lambs were heavier than female and twine lambs at birth, weaning and fifth month of age. Ewe weight did not show significant effect on lamb body weight traits. Ewe age had a significant effect on birth weight and non-significant effects on weaning and fifth month body weights. Also, lamb birth weight had a significant effect on latter body weights and heavier lambs at birth showed more weights at weaning and fifth month. Body condition score showed significant effect on litter size and lamb weights at different ages. Lamb of ewes with BCS 3 and higher were heavier at birth, weaning and 5th month. The highest rate of twinning was recorded in ewes with BCS 3.
These results suggested that Chaal ewes with at the least BCS of 3 at mating had better productive performance and flushing could be used to improve productive and reproductive abilities in ewes with less BCS.