RELATIONSHIPS BETWEEN BODY CONDITION SCORE, BODY-WEIGHT AND INTERNAL FAT DEPOSITS IN LATXA EWES

The relationships between body weight (BW), body condition score (BCS) and internal fat deposits were studied in Latxa dairy ewes. In 2 year s, the BW and BCS of 20% of the ewes in 14 flocks were recorded at the beginning of the mating period (pre-mating), and in the Ist month of lactation (post lambing). BW increased with age (BW = 54.05 x (1-e(-0. 988 x age)), and the mature weight was not reached until 4 years, afte r which weight did not differ between pre-mating and post-lambing peri ods. Body condition score, however, differed between the two periods. The regression coefficients (b) of BW on BCS, when flock-year and age were included in the regressions, differed significantly (P < 0.05) in the pre-mating and post-lambing periods, and were 5.3 (s.e. 0.31) and 6.3 (s.e. 0.43) kg per unit BCS, respectively. The correlation coeffi cients (r) were 0.77 and 0.71 respectively, compared with 0.42 and 0.3 8 when the flock-year and age of the ewes were not included in the reg ression. Thirty-seven of these ewes, with BCS between 0.75 and 4.00, w ere slaughtered, the weights of omental, mesenteric and kidney and cha nnel fat recorded, and the lumbar fat thickness assessed at the last r ib. The regressions between the weight of fat deposits and lumbar fat thickness and BW and BCS fitted to semi-logarithmic equations, except for mesenteric fat, in which the relationship was linear. Body conditi on score was a better predictor than BW for individual fat deposits, w ith proportionately 0.81 to 0.83 of the variation in the weight of the deposits accounted for by variation in BCS and 0.57 to 0.70 by variat ion in BW.