Effects of two different rates of body weight gain during the first trimester of pregnancy or supplementing vitamins and minerals throughout pregnancy on primiparous beef cow milk production and composition

Summary

This three-experiment field study in crossbred Angus heifers examined how prenatal nutrition management influences colostrum and milk quality in primiparous beef cattle. Moderate body weight gain (0.79 kg/d) during the first 84 days of pregnancy reduced colostrum somatic cell counts and increased milk protein concentration compared to low gain (0.28 kg/d), suggesting improved colostrum immunological quality and subsequent milk composition. In contrast, vitamin and mineral supplementation (113 g/heifer/day) from breeding to parturition produced no significant effects on milk yield or composition, indicating that supplemental micronutrients alone may not substantially alter milk production metrics under the conditions tested.

Regional applicability

The findings may be partially applicable to UK beef systems, particularly regarding the importance of adequate early-pregnancy nutrition for heifer development and colostrum quality, which influences calf health outcomes. However, UK management systems, pasture quality, forage composition, and herd genetics may differ substantively, requiring localised validation before applying these specific supplementation protocols.

Key measures

Colostrum somatic cell count (cells/mL); milk protein percentage; milk fat percentage; 24-hour milk yield (kg); milk composition; postpartum day; sampling technique effects (manual stripping vs. oxytocin administration with lag time)

Outcomes reported

The study measured colostrum somatic cell counts, milk yield, and milk composition (protein, fat, solids-not-fat) in primiparous beef heifers across three experiments varying prenatal body weight gain rates and vitamin–mineral supplementation. Sampling techniques and their effects on measured milk composition were also evaluated.

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