Relationships between body condition score, body weight and internal fat deposits in Latxa ewes

Abstract

AbstractThe relationships between body weight (BW), body condition score (BCS) and internal fat deposits were studied in Latxa dairy ewes. In 2 years, 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 1st month of lactation (post lambing). BW increased with age (BW = 54·05 × (1-e−0·988 × age), and the mature weight was not reached until 4 years, after which weight did not differ between pre-mating and post-lambing periods. 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 coefficients (r) were 0·77 and 0·71 respectively, compared with 0·42 and 0·38 when the flock-year and age of the ewes were not included in the regression.Thirty-seven of these ewes, with BCS between 0·75 and 4·00, were slaughtered, the weights of omental, mesenteric and kidney and channel fat recorded, and the lumbar fat thickness assessed at the last rib. 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 condition score was a better predictor than BW for individual fat deposits, with 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 070 by variation in BW.