EFFECT OF ADDING NIACIN IN MILK YIELD AND SOME OF ITS COMPOSITION FOR FRIESIAN COWS IN SUMMER IN CENTRAL OF IRAQ

Abstract

This study was conducted in AL-Ishaqi Cattle Station, north of Baghdad, and use of 36 multiparous Friesian cows in the early stage of lactation, cows were divided randomly into three equal groups, during the period of 1St June 2010 to Thirty August 2010, to study the effect of niacin supplementation on average of weekly milk production, quick access to the peak lactation and length, and and some of milk composition (Protein, fat and lactose) The results showed a highly significant effect of niacin supplementation level 6 and 12g on Increasing weekly milk production for June, July and August, The speed of access to the peak lactation and the length of the peak of the Cows had significantly affected )P<0.01) by niacin supplementation namely 37.66 days and 74.75 days respectively as compared to the control (52.16 days and 47 days) The influence of niacin supplementation was had a significant effect on milk composition (protein, fat and lactose), most months of the experiment, so that the average milk components mentioned above for the two group of cows that received niacin during August were 3.45, 3.22 and 4.53 % respectively, while it were 3.18, 2.21 and 3.97% for the cows in control group, it seems clear that exposure dairy cattle to heat stress in summer had a negative effect on performance of productive, and niacin supplementation (12 and 6 g/cow/ day) led to the mitigate the adverse impact of heat stress and a general improvement in the performance of these cows.