Effects of free gossypol in the diet of pregnant and postpartum Brahman cows on calf development and cow performance3

Abstract

Pregnant Brahman cows (n = 38) and heifers (n = 12) were assigned, 90 d before expected calving dates, to one of three treatment groups: 1) 0 g of free gossypol(FG).animal-1.d-1 (FGHD) from soybean meal (SBM), controls; 2) 2 g of FGHD from SBM and cottonseed meal (CSM), low FG; or 3) 4 g of FGHD from CSM, high FG, to determine the effects of dietary FG on prepartum and postpartum cow performance, calf development, and selected blood variables. Prepartum and postpartum cow BW, 4-h milk production, and calf BW were similar (P > .10) among treatments. Following 84 d of treatment, cows receiving 4 g of FGHD tended (P < .10) to have greater erythrocyte fragility (EF) than cows given 0 or 2 g of FGHD. Mean EF for the 112-d postpartum period were greater (P < .05) in cows given 4 than in those given 0 g of FGHD. Dietary FG consumption by the dam did not affect (P > .10) calf EF. Serum triiodothyronine (T3) and thyroxine (T4) in cows and T4:T3 ratio in calves were similar (P > .10) among treatments. After 84 d of treatment, cows receiving 4 g of FGHD had lower (P < .05) serum concentrations of alpha-tocopherol and beta-carotene than cows given 0 g of FGHD. At parturition, serum alpha-tocopherol and beta-carotene were similar (P > .10) for all cows and calves. On d 7 and 28 after calving, alpha-tocopherol tended to be lower (P < .10) and beta-carotene was lower (P < .05) in calves given 4 than in those given 0 g of FGHD. Calf metacarpal medial cortex tended to be greater (P < .10) in calves from cows given 0 than in those from cows given 2 or 4 g of FGHD, and the lateral cortex (treatment x sex; P < .05) was smaller in male calves from cows given 4 than in those from cows given 0 g of FGHD but was not affected in female calves. By 96 to 105 d after calving, a greater number of (P < .05) cows consuming 4 and 2 g of FGHD experienced luteal activity, and a greater (P < .10) number than of cows receiving 0 g of FGHD had conceived by 112 d after calving. In summary, pre- and postpartum consumption of FG may have impaired some aspects of calf skeletal development and vitamin metabolism, although long-term performance of cows and calves was not affected.