Influence of pre‐ and post‐calving pasture allowance on hill country beef cow and calf performance

Abstract Sixty pregnant beef cows of Friesian, 7/8 Friesian X Jersey, and Angus genotypes 3 years of age and older were used. At 56 days before calving, each cow was allocated to 1 of 2 daily pasture DM allowance levels: 20 (“20”) and 8 (“8”) kg DM per cow. At calving cows were re‐assigned to daily pasture allowances of 20 (“20‐20” and “8‐20”) or 8 (“20‐8” and 8‐8”) kg DM per cow for 56 days post‐partum. At 56 days after calving, the cows were grouped into a single mob and given a daily allowance of 18 kg DM per cow throughout mating and until weaning. Despite similar pre‐calving weights, “20” cows were 36 kg heavier (P < 0.01) immediately after calving than “8” cows. Forty‐two days after calving the visually assessed condition scores of “20” cows remained consistently higher (P < 0.05) than the score of “8” cows. Mean DM intakes (kg/cow/day) for “20” and “8” cows before calving were 9.5 and 6.3 respectively. Mean DM intakes (kg/cow/day) (and % DM utilisation rates) for “20” and “8” cows before calving were 9.5 kg (47.6%) and 6.3 kg (78.2%) respectively. At 56 days after calving, “20‐20” and “8‐20” cows weighed 520 kg and 502 kg respectively and were heavier (P < 0.01) than “20‐8” and “8‐8” cows (340 kg and 392 kg); condition scores were significantly different (P < 0.05) at 6.8, 6.0, 3.4, and 2.5 respectively. Treatments did not affect calf weights until 56 days of age when calves of “20‐20” (76 kg) and “8‐20” (81 kg) cows were heavier (P < 0.05) than those of “8‐8” cows (67 kg); calves out of “20‐8” cows (74 kg) were intermediate. Intakes (kg DM/cow/day) for “20‐20”, “8‐20”, “20‐8”, and “8‐8” cows during the 56 days after calving were 10.5, 11.7, 6.8, and 7.0 kg respectively. From 56 days post‐partum until weaning, gains in cow live weight (and condition score) were − 5 kg (− 0.2), 44 kg (2.0), 4 kg (−0.1), and 58 kg (2.7) for “20‐20”, “20‐8”, “8‐20”, and “8‐8” cows respectively. Corresponding calf weight gains (kg) were 81, 83, 83, and 83. The mean intervals (days) from calving to first oestrus were 72, 80, and 69 for “20‐20”, “20‐8”, and “8‐20” cows respectively, shorter (P < 0.05) than the 97 days of “8‐8” cows. Pre‐calving pasture allowance had no effect on interval from calving to first oestrus or pregnancy rate, but both these traits were affected by post‐calving allowance.