Effects of liveweight gain of 15-month-old Angus heifers during the first trimester of pregnancy on liveweight and milk intake of their calves

Nutritional methods of manipulating birthweight of calves would be beneficial for managing dystocia in beef heifers. Sixty-five 15-month-old Angus heifers were managed under the following liveweight gain treatments for the first 42 days and then from 42 to 90 days of pregnancy: treatment 1: high liveweight gain throughout (881 ± 59 g/day and 212 ± 45 g/day); treatment 2: low liveweight gain throughout (182 ± 60 g/day and -565 ± 47 g/day); and treatment 3: low then high liveweight gain (217 ± 59 g/day and 379 ± 44 g/day). Heifers were managed in one herd from day 90 of pregnancy until parturition. The birthweight of calves was not affected by treatment, and was 32.3 ± 0.9 kg, 32.9 ± 0.9 kg and 32.5 ± 0.9 kg for treatments 1, 2 and 3, respectively. calves born to heifers in treatment 2 consumed less milk at 90 days of age than calves from heifers in the other treatments (P < 0.05). Weight gain restriction in the first trimester of pregnancy did not reduce birthweight of calves, and therefore could not be used to manage dystocia in heifers.