Effects of supplemental dietary biotin on performance of Holstein dairy cows.
An experiment was conducted to evaluate the effect of different levels of biotin on productive performance of Holstein dairy cow. In this experiment a change-over design with twelve multiparous cows, three rations and three periods was employed. Ingredients of the basal diet were alfalfa hay (24%) corn silage (16%) and concentrate (60%) on dry matter basis. The experimental diets 1 to 3 contained 0, 10 and 20 mg of biotin per day, respectively. The rations were fed to cows as Total Mixed Rations (TMR), but biotin was top-dressed on the a.m. allotment of ration. The cows were individually ad libitum and milked three times per day. Daily milk yielded was recorded and samples of the milk were taken once per week for determination of milk composition. Blood were taken in end of each period. Dry Matter Intake (DMI) and milk yield of cows were not affected by biotin. Also milk compositions were not affected by biotin. The average of Fat Corrected Milk (FCM) yield for 4% fat for rations contain 0, 10 and 20 mg day(-1) biotin, respectively 25.45, 26.2 and 25.9 kg day(-1) were calculated. Blood concentration of were unaffected by different levels of biotin. The differences between averages of the milk cows were not significant.