Effect of Supplementation of Niacin on Milk Yield and its Composition in Lactating Crossbred Cows During Summer

The present study was conducted on eighteen crossbred lactating cows (Days in milk= 11.56; 2^nd to 4^th lactation) divided into three groups on the basis of average milk production. All the animals were fed basal ration consisting of wheat straw (20%), chaffed green maize fodder (40%) and compounded concentrate mixture (40%) as per NRC (2001). Animals in treatment group were fed the same basal diet along with the daily niacin supplementation of 600 (T₁) and 800 (T₂) mg/kg of DM. The trial lasted for 120 days (25^th April to 25^th September, 2012). The maximum temperature, minimum temperature, relative humidity and dry-wet bulb temperature were recorded daily in morning (7:30 am) and afternoon (2:30 pm) and THI was computed. Animals were in moderate stress during morning, whereas in the afternoon the animals were severely stressed. The milk yield, 4% FCM, ECM, SCM and milk energy remained unaffected by supplementation of niacin. The results of average milk components and yield (% and kg/d) viz., milk fat, protein, lactose, SNF and total solids were also not influenced by different treatments. Milk urea concentration was significantly (P<0.05) higher in T₂. However, there was no difference between control and T₁ group. Milk niacin (mg/L) was significantly higher (P<0.01) in T₁ (0.32±0.01) and T₂ (0.32±0.01) as compared to control (0.22±0.01). It was concluded that niacin supplementation had no effect on milk yield and its composition, however, milk niacin level was improved.