PSII-A-5 Effects of Time Postpartum and Late Gestational Nutrient Restriction on Beef Heifer Colostrum

Abstract Our objectives were to determine changes in colostrum yield and composition across the 36 hours post-calving effects of late gestational nutrient restriction (NR) on these changes. Fall-calving, crossbred beef heifers (BW: 472 ± 33 [SD] kg; BCS: 5.4 0.5) individually fed 100% (control; CON; n = 13) or 70% (NR; NASEM metabolizable energy protein requirements for maintenance, growth, pregnancy from d 160 gestation parturition. Calves removed dams immediately pre-suckling. Colostrum was hand-milked all quarters at 1, 12, 24, h total volume weight. protein, triglycerides, milk urea nitrogen (MUN) concentration analyzed using colorimetric assays a UV-visible light microplate reader. Data fixed treatment, hour, treatment × hour (repeated measures); calf sex, maternal sire, initiation date covariates. affected (P < 0.02) by interaction. weight 28% less ≤ 0.03) NR than CON 1 h. For both treatments, decreased 0.04) 12 h, before increasing Triglyceride greater CON. Both triglyceride 0.01) 24 Protein 0.001) Total triglycerides MUN increased 0.004) In conclusion, may only affect content decreases dramatically after first milking.