Pre-calving nutrition of Angus beef breeding cows

Abstract

An investigation was carried out into the effects of liveweight gain of beef cows grazed on good quality autumn-saved pasture before their calving in the spring. One hundred and twenty-one mixed-age Angus breeding cows which had lost c. 9.5% of their autumn liveweight during the winter, were randomly allocated to 2 treatments. The 60 cows in treatment H were fed for 6 weeks before calving so that they gained liveweight at the rate of about 0.5 kg/day. The 61 cows in treatment L-H were fed for 4 weeks to gain at the rate of about 1.0 kg/day. Both groups of cows attained a similar liveweight at the commencement of the calving season. The immediate effect of the pre-calving nutritional treatments was to alter the calving date distribution of the cows in each group (P<0.05). Although the mean calving date of the cows in both treatments was the same, a higher proportion of cows in the H group calved in the period at the tail of the calving date distribution. The treatments did not, however, affect calf birth weight, calf weaning weight, and calf milk consumption. There was evidence of an effect of pre-calving liveweight change of a cow on the length of her post-partum anoestrous period.

Keywords:

• beef cows
• Angus
• nutrition
• calving
• liveweight gain