The effect of replacement soybean meal with fish meal on milk production, milk ‎composition and reproductive performance in repeat breeder Holstein cows ‎

The objective of this experiment was to determine the effects of fish meal supplementation on productive and reproduction performance in repeat breeder Holstein cows. Two hundred and sixty-one multiparous Holstein cows with at least three consecutive unsuccessful inseminations, without clinically detectable reproductive disorders, were randomly allocated to 1 of 3 dietary treatments. Dietary treatments were control, 2.5 or 5% fish meal, that replaced soybean meal. Cows were timed inseminated following the Double-Ovsynch protocol. Milk yield was (38.49, 39.92, and 41.42 kg/d, for cows fed the control, 2.5 and 5% FM diets respectively) of which the difference (P<0.01) between the control and 5% FM diets was significant. Likewise, 4% FCM was higher for treatment 5% FM relative to control (P<0.05). Milk fat, protein and lactose content (%) were not different among treatment (P>0.05) but milk protein yield was higher (P<0.05) for cows fed the 5% FM than control and 2.5% FM diets was significant. Plasma and milk urea nitrogen concentrations decreased significantly (P<0.05) affected fish meal by consumption. Plasma cholesterol concentration was higher for cows fed 5% FM compared to the control diet (P<0.01). Plasma progesterone concentration at 16 d post artificial insemination was greater for treatment 5% FM relative to control treatment (P<0.05). Pregnancy at the first service and cumulative (1st and 2nd service) for cows fed 5% FM content higher than control diet (P<0.05). These results indicated that supplementation the diet with 5% fish meal improved fertility and productive performance in repeat breeding cows.