A comparison of the effects of three nutritional levels in late pregnancy on beef cows and their calves

Abstract The effects of a high, in contrast with a low, plane of nutrition until approximately eight or three weeks before calving, on the performance of hill country beef cows and their calves to weaning, are described. On 31 May 1966 114 four‐ to eight‐year‐old pregnant Aberdeen Angus cows were formed into three balanced groups. Thereafter, one group was fed a high plane of nutrition until calving (H), a second group a low plane of nutrition until about eight weeks (58 ± 15 days) before calving then a high plane (L‐H 8 ), and a third group a low level of feeding until three weeks (23 ± 14 days) before calving then a high plane (L‐H 3 ). All cattle were fed on a high plane between calving and weaning. Mean cow live weight changes from 31 May to the last live weight recorded prior to calving were 0.47, 0.07, and 0.32 lb per day, and between post‐calving and weaning 0.29, 0.50, and 0.66 lb per day, for the H, L‐H 8 , and L‐H 3 treatments respectively. By weaning, about 150 days after calving, no significant differences in cow live weights between treatments were found. Mean calf birth weights were 60.S, 56.4, and 52.9 lb for the H, L‐H 8 , and L‐H 3 treatments respectively. No significant differences in calf live weights were evident by weaning. The number of calves present at weaning as a percentage of those born was 91.2%, 92.1%, and 87.8%, for the H, L‐H 8 , and L‐H 3 treatments respectively. Evidence of residual effects of the previous year's post‐calving plane of nutrition on the live weight change of the cows over the pre‐calving period, calving date, and on calf birth weight in the current experiment was found.