Body condition scoring in relation to changes in body weight and performance in Belgian Blue double-muscled beef cows

Abstract

The relationship between the body condition in Belgian Blue double-muscled cows and the performance of cows and calves has been studied over a 5-year period. One hundred and twenty-six cows, with a mean initial parity of 1.6 ± 1.1 were involved. During each winter, they were fed 100, 90, 80 or 70% of their energy requirements (140-day restriction period). At the end of April, all cows were turned out on pasture in identical circumstances (re-alimentation period). Half of the cows were suckled by their offspring; the other cows were dried off following calving and colostrum collection. Body condition score (BCS; scale 0 to 5) was determined at the start and end of the restriction period and the re-alimentation period, at monthly intervals and at calving. Two hundred and thirteen parturitions were involved, of which 63% occurred during the first half of the year. BCS (mean of monthly observations) was lower (P < 0.001) in primiparous (1.45) cows than in cows with two (1.69) or more parturitions (1.81). BCS (mean of monthly observations) was lower in suckling cows (1.51) than in dry cows (1.79; P < 0.001). BCS (mean of monthly observations) was reduced by energy restriction from 1.75 to 1.56 (P < 0.001). BCS-change during the restriction and re-alimentation periods was related to body weight change (R 2 = 0.538). BCS- change was negative during the restriction period, but it was more than compensated for during the re-alimentation period. BCS at calving was not related to the length of the subsequent calving interval. Cows with a BCS less than 1.5 at calving, yielded less milk and calf performance was reduced when compared with those with a BCS over 1.5. The dams of calves that died at birth had a lower BCS at calving (1.45) than the dams of surviving calves (1.75; P = 0.044). Open cows at 9 months postpartum had a higher BCS at calving (1.78) than cows that became pregnant within 9 months postpartum (1.50; P < 0.001). Consequently, it is difficult to define a universal optimum BCS for double-muscled cows, resulting in a maximal milk production and calf growth, a low calf loss and cow culling rate and a calving interval of approximately one year. body condition / body weight / cow / double-muscling / calving interval / milk yield / calf performance