تاثير جايگزيني پودر ماهي كيلكا با كنجاله سويا بر توليد و تركيب شير و غلظت متابوليتها و پروژسترون پلاسماي گاوهاي تازه زاي هولشتاين

Effect of replacing kilka fish meal for soybean meal in diet of early postpartal Holstein cows on milk production and composition, progesterone and several blood metabolites

The effect of replacing soybean meal with Kilka fish meal in the diet of early postpartal Holstein cows was studied. Twelve multiparous Holstein cows (27±2 days in milk) received diets containing either 0.0% (Ti), 2.5% (T2) or 4.0% (T3) Kilka fish meal. Ovarian cycles were synchronized using the Pre-Synchronization I Ovsynch protocol on day 35 of lactation. Feed intake and milk yield were determined daily, and milk composition was measured at weekly intervals. Blood samples were taken from the coccygeal vein on day 61 and 68 for determination of plasma concentrations of progesterone and cholesterol. On day 80 of lactation, blood sampling was repeated at 0, 1.5, and 4.0 h after morning meal for determination of plasma levels of glucose, urea nitrogen and soluble proteins. Dry matter intake, milk yield, milk composition, and plasma progesterone and cholesterol levels were not significantly affected by the diet. Dry matter intake was increased linearly with time (P<0.001). The proportion of cows having plasma progesterone concentration higher than one ng/ml on day 61 (day of GnRH injection in the synchronization protocol) and on day 68 (day of prostaglandin injection) was greater in T3 group (P<0.05). Plasma concentrations of glucose, urea nitrogen and soluble proteins were not significantly affected by the diets but plasma glucose and soluble proteins varied over time (P<0,01). In conclusion, at the levels used in this experiment Kilka fish meal had no significant effect on lactation performance, progesterone and several blood metabolites in early postpartal Holstein cows.