Effect of supplementing calcium salts of n-3 and n-6 fatty acid to pregnant nonlactating cows on colostrum composition, milk yield, and reproductive performance of dairy cows

Abstract

The objective of this study was to determine the effect of dietary supplementation with calcium salts of n-3 and n-6 fatty acids (FA) during the last 3 weeks of gestation on colostrum composition and productive and reproductive performance of nulliparous and parous Holstein cows during the entire subsequent lactation. During the last 3 weeks of pregnancy, cattle (n = 120), within parity, were randomly assigned to 1 of 3 treatments, no fat supplement (CON), a Ca-salt supplement enriched in C18:2n-6 (CSO), or a Ca-salt supplement enriched in eicosapentaenoic and docosahexaenoic acid FA (CFO). After calving, all cows received a common lactation diet. As expected, cows fed CSO or CFO produced colostrum with higher (P < 0.01) contents of n-6 or n-3 FA, respectively. Colostrum yield and composition were not affected by treatments, but cows fed fat produced colostrum with higher (P < 0.01) IgG concentration. The major impact of treatments on productive and reproductive performance was observed for the contrast comparison of supplemental fat (CSO and CFO) compared with CON. Body weight was not affected by treatments, but at 14 weeks after parturition, cows fed fat tended (P = 0.07) to have a greater body condition score compared with CON cows. Milk yield and 4% fat corrected milk were higher (P < 0.001) for cows fed fat compared with CON (37.8, 34.9 versus 35.2, 33.0 kg/d, respectively) during the experimental period. Milk fat content was higher (P < 0.001) in CON cows compared with cows fed fat (36.1 vs. 34.9 g/kg, P < 0.001). Plasma cholesterol concentrations were higher (P ≤ 0.02) for both fat supplement groups during the pre- and postpartum period, but plasma concentration of non-esterified FA was lower (P < 0.01) for fat-supplemented compared with CON-supplemented cows during postpartum. Fat-supplemented cows had shorter days to first estrus and first insemination (P < 0.04). Total reproductive disorders tended (P = 0.06) to be lower in cows fed supplemental fat than in those fed CON. Cows fed supplemental fat had lower (P = 0.01) incidences of total health disorders compared with those fed CON diet. In summary, prepartum fat supplementation increased milk yield during the entire lactation and improved reproductive performance. Our findings suggest that the benefits of supplemental polyunsaturated FA during the prepartum period only is independent of the n-type of FA.