An on-farm trial of 7 days preliminary feeding and 90 days experimental period was conducted in village Mumanvas, Vadgam Taluka of Banaskantha district of Gujarat during September to November 2012. Twelve lactating crossbred cows of uniform body weight, milk yield and with 2nd and/or 3rd lactation number in initial stage of lactation were selected for experiment to study the effect of bypass fat supplementation. Six healthy animals in each group allotted to two dietary treatments. Completely randomized design was followed for making treatment groups i.e. T1: control (concentrate mixture + green fodder + dry fodder) and T2: treatment (T1+bypass fat@10 g/kg milk yield). The nutrient requirement of animals meets out as per the ICAR (1998) guideline. Milk yield of morning and evening was recorded daily and sampled every fort night interval. At the end of experiment, digestion trial of 7 days was under taken. The average daily DMI (kg/h), CPI (g/h), DCP intake (g/h) and TDNI (kg/h) in T1 and T2 groups were 13.80±0.20 and 14.07±0.43; 1786.70±32.48 and 1871.35±76.35; 1222.32±48.95 and 1329.80±77.60; 8.39±0.15 and 9.33±0.32, respectively. The DMI, CPI and DCPI were found statistically non significant between treatment groups. While as, TDNI was found to be significantly (P<0.05) higher in bypass fat group. The cumulative DMI, CPI, DCPI and TDNI (kg/90d) in T1 and T2 were 1242.32 ±18.28 and 1265.94±39.06; 160.80±2.92 and 168.42±6.87; 110.01±4.40 and 119.68±6.98; 755.38±13.33 and 839.78±28.67, respectively. The TDNI was differ statistically (P<0.05) between treatment groups while statistically non significant difference between treatment groups in terms of cumulative DMI, CPI, DCPI. The average daily production of whole milk, 4% FCM, fat and SNF in experimental crossbred cows in groups T1 and T2 were, 15.67±0.43 and 17.78±0.81, 15.30±0.74 and 18.55±0.90; 0.60±0.04 and 0.77±0.04 and 1.31±0.03 and 1.53±0.06 kg/h/d, respectively and all values were statistically (P<0.05) significant and higher in bypass fat fed group than control group. The cumulative yield (kg/h/90d) for whole milk, 4% FCM, fat and SNF were, 1410.11±38.96 and 1600.01±72.88; 1376.85±66.31 and 1669.32±80.60; 53.57±3.81 and 69.05±3.66 and 118.32±2.56 and 138.02±5.72 in T1 and T2 groups, respectively. The cumulative yield was significantly (P<0.005) higher in bypass fat fed group as compared to control.The percent of milk fat, total solid and SNF of experimental cows in groups T1 and T2 were, 3.82±0.11 and 4.32±0.12; 12.24±0.22 and 12.94±0.13 and 8.40±0.06 and 8.64±0.09, respectively. The fat percentage, total solid percentage and SNF percentage were statistically (P<0.05) significant and higher in the group which was fed bypass fat supplementation. 

Keywords: Bypass fat; SNF; DCP; TDN; Nutrients; Crop residues; Palabality; Digestibility