Prepartum nutrition and solar radiation in beef cattle: II. Residual effects on postpartum milk yield, immunoglobulin, and calf growth.

Abstract

Residual effects of nutrition and solar radiation during the last two-thirds of gestation on postpartum milk yield, immunoglobulin (Ig) G and M in both colostrum and calf serum, and calf growth were determined in beef cattle. Nineteen mature, multiparous crossbred cows (Bos taurus) at d 90 of pregnancy were assigned to either low (LO, 70% NRC total energy intake) or high (HI, 110% NRC total energy intake) nutritional level (sudangrass hay) and to either shade (S) or no shade (NS) treatments in a 2 x 2 factorial experiment. After parturition, all cows were moved into a large paddock and managed uniformly. Calf weights and calf serum were collected within 1 d postpartum, thereafter at 2-wk intervals for the next 12 wk, and then at 4-wk intervals until weaning. Colostrum samples were taken from the cow and milk yields were determined by the "weigh-suckle-weigh" technique. Neither prepartum nutrition nor environment influenced lactational performance of the dam. Concentrations of IgG were elevated in the colostrum of LO cows (15.3 vs 7.8 g/100 mL, LO vs HI, respectively; P < or = .05) but were not affected by shading. The patterns of IgG concentration in the calf serum were not altered by prepartum nutrition or environment; however, the pattern of IgM concentrations was greater (P < or = .01) in calves from S cows than in those from NS cows. This difference in IgM profile did not seem to be due to any residual effect from prepartum treatments. Postnatal growth of calves from birth until weaning were similar across all prepartum treatments.(ABSTRACT TRUNCATED AT 250 WORDS)