Vitamin A is critical for immune function and epithelial integrity, yet the relationship between maternal and calf vitamin A status is not well defined. This study evaluated cow-calf vitamin A status under restricted maternal vitamin A intake during late gestation and early lactation. Beef cows (n = 114) were individually fed 14,000 or 29,000 IU/d of vitamin A (approximately 30% or 75% of recommendations) from 128 days pre-calving to 32 days post-calving. All cows began with high liver retinol concentrations (mean ± SD: 786 ± 252 μg/g DM) from prior grazing. Cow liver and plasma, and calf liver and plasma, were sampled 32 ± 7 days postpartum. Cow liver retinol declined to 483 ± 182 μg/g DM by 32 days postpartum. Calf liver retinol averaged 51 ± 27 μg/g DM and plasma retinol 190 ± 47 ng/mL, both below adequacy thresholds. Calf plasma retinol increased with calf liver retinol (p 2 = 0.22). Maternal post-calving liver retinol explained 9.5% of the variation in calf liver retinol. These results indicate that adequate maternal liver vitamin A stores at calving do not ensure adequate calf vitamin A status when maternal dietary vitamin A is restricted.
Speer et al. (Thu,) studied this question.