The effects of a nutritionally unbalanced diet on some blood and postpartum fertility parameters in dairy cows

This study was carried out to determine the effects of mineral imbalances and negative energy balance on reproductive functions during the early and later stages of the postpartum period in dairy cows. The study included 100 randomly selected multiparous Holstein cows aged between 2 and 8 years ( mean weight: 650 kg). The animals' diets were not manipulated and they were fed the rations used by the study farm. Blood samples were taken on postpartum days 0, 20, 24, 30, 31, 38, 45, 60, and 90. Cows with calving and/ or puerperium problems were recorded. Analyses were made for non-esterified fatty acids, calcium, phosphorus, magnesium, urea nitrogen, SGOT (AST), and progesterone levels in the blood. Non-esterified fatty acid levels in blood serum were 670, 660, 660, 620, and 640 mu mol/l on postpartum day 0, 20, 30, 60, and 90, respectively. It was assumed that those levels might be indicators of significant negative energy levels in the rations. The Ca: P ratio in blood samples was 1: 1.25. In all, 31% of the animals' serum progesterone levels increased until the 45th postpartum day, whereas progesterone levels were below 1 ng/ml in 69% of the animals. The fertility parameters of the cows with or without postpartum problems were, respectively, as follows: calving to first service interval: 102.44 +/- 36.41 and 108 +/- 28.61 days; calving to conception interval: 132.69 +/- 34.00 and 128.63 +/- 35.50 days; services per conception: 2.00 +/- 0.70 and 2.12 +/- 0.71; repeat breeder rate: 33.3% and 37.93%. These parameters indicate infertility and economic lose for the study farm.