Concentrations of Various Constituents in Blood of Dairy Cows During Stages of Terminal Gestation and Initial Lactation

Abstract

Determinations were made of tocopherol concentrations in the blood serum of dairy cows receiving typical barn rations, unsupplemented or supplemented, during stages of terminal gestation and initial lactation. Tocopherol concentrations in the blood serum of dairy cows restricted to typical barn rations decreased slowly during the terminal month of pregnancy. The decline generally became more pronounced within a few days before parturition and reached a minimum level the second day post partum, after which a gradual but continuous rise ensued. Addition of vitamin A supplements to the diet of the preparturient dairy cow had no significant effect on tocopherol levels in the blood serum. Addition of tocopherols (0.5 to 1 gm) to the diet resulted in concentrations of blood serum tocopherols averaging more than 15% higher than those in the controls. Addition of large tocopherol supplements daily to typical barn rations of dairy cows during the concluding month of gestation resulted in an increase in tocopherol levels in blood serum, the highest level of tocopherol supplementation (10 gm daily) eliciting the greatest response (approximately 4 times higher than in the controls). The higher levels of tocopherol supplementation, 4 gm to 10 gm daily, counteracted the gradual downward prepartal trend in blood serum concentrations of this vitamin which was characteristic of serum from cows receiving no tocopherol supplements, but did not prevent the rapid decline in the immediate parturient period. After cessation of tocopherol supplementation at parturition, the post partum trends of blood serum tocopherols were similar for all groups; however, high levels of prepartal supplementation delayed the time of attainment of the minimum level and tended to maintain higher concentrations subsequently.