Effect of Dry Period Overconditioning on Subsequent Metabolic Disorders and Performance of Dairy Cows

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Abstract
In 2 trials with 44 cows over an 8 wk dry period, control cows were fed alfalfa forage and minimal grain compared to liberal grain plus corn silage (trial 1) or plus alfalfa forage (trial 2). Following parturition all cows were fed to meet requirements. In trial 2 1/2 of each group received nicotinic acid at .apprx. 12 g daily for 8 wk, starting on the 8th day postpartum. In trial 1 overconditioned exceeded control in prepartum insulin 41.4 to 23.5 .mu.U[unit]/ml, free fatty acids of plasma 1 wk postpartum 23.9 to 19.0 mg/100 ml and 2 to 4 wk postpartum 16.3 to 12.1 mg/100 ml, body weight gain during the dry period 77.1 to 38.5 kg. In trial 2 overconditioned exceeded control only in intake of digestible energy during the dry period 42.9 to 38.1 Mcal/day and postpartum 64.1 to 62.3 Mcal/day along with milk protein 3.39 to 3.20%. Cows fed nicotinic acid showed an advantage over controls in body weight change +1.41 to -3.75 kg/wk, digestible energy intake 64.1 to 62.2 Mcal/day and cholesterol of plasma 175 to 204 mg/100 ml. Liver biopsies 2 days postcalving in overconditioned compared to controls showed total lipids 12.5 to 9.8%, triglycerides 67.3 to 30.5 mg/g, phospholipids 19.8 to 27.7 mg/g and triglyceride: phospholipid ratio 3.4 to 1.1. Total cases of periparturient diseases of combined trials were 31 overconditioned and 21 control during the first 11 wk postpartum.