Effect of Supplemental Fish Meal on Milk Yield and Milk Composition of Holstein Cows during Early Lactation

Abstract

Data of 15 multiparous Holstein cows kept at Ibaraki Prefectural Animal Experiment Station were collected from 10 weeks prepartum to 20 weeks postpartum. Cows were assigned randomly to a soybean meal (SBM) diet or a fish meal (FM) diet from 4 weeks before expected calving date to 20 weeks postpartum. Each diet was formulated to contain similar amounts of CP, ADF, and NDF. In the FM diet, 2.5 and 5% of fish meal were supplemented as total mixed rations in prepartum and postpartum periods, respectively. Compared to the SBM diet, undegraded intake protein (UIP) and Met were higher in the FM diet, but Lys was low. Body weight and dry matter intake were not affected by supplemental FM, and dry matter intake increased by 6 weeks postpartum and maintained constant after 7 weeks postpartum. Cows in the FM diet remained high milk production during the experimental period, but milk yield in the SBM diet decreased gradually after 6 weeks postpartum. Supplemental FM increased milk yield and protein yield from 10 to 20 weeks postpartum when FM intake was 1.19 kg/d, although milk protein was not improved. There were no significance differences in fat content and fat yield between FM and SBM diets. Supplemental FM had no effect on plasma glucose and urea-N at parturition and 7 weeks postpartum. Thus, the increased milk and protein yield may be due to the combination of carryover effect of supplemental UIP or Met in FM from 4 weeks prepartum to 10 weeks postpartum and direct effect of supplemental FM.