Effect of feeding undegraded intake protein at a level greater than National Research Council recommendation on the lactational performance of crossbred cows

Feeding two levels of undegraded intake protein (UIP) was studied in late lactation crossbred dairy cows, as affecting dry matter intake (DMI), digestibility, nitrogen (N) balance, milk yield and milk composition. The study included a feeding trial and a metabolism trial. The feeding trial was carried out during two periods of 7 weeks in a switch-over design using two groups of four multiparous cows. Group I was fed UIP according to NRC [National Research Council, 1989. Nutrient Requirements of Dairy Cattle, 6th Revised Edition. National Academic Press, Washington, DC, pp. 138–147] (NRC-UIP) and Group II received 260 g per day more (HNRC-UIP). The diet consisted of mixed straw of finger millet and paddy (FM-P) and a compound feed mixture (CFM). ughage DMI for NRC-UIP and HNRC-UIP was 3.83 and 3.66 kg per day, respectively. The 4% FCM yield was equal for the two groups and amounted to 11.1 kg per day. The fat, SNF and protein contents (%) for NRC-UIP and HNRC-UIP were, respectively, 4.53, 8.72, 3.69 and 4.71, 8.73, 3.67. The roughage DMI, body condition score, milk yield and milk composition were not significantly different (P>0.05). On the other hand, N retention (g per day) in HNRC-UIP (103) was higher than in NRC-UIP (55) (P<0.01). The results indicated that although N balance improved with feeding higher UIP levels, it had no beneficial effect on roughage DMI, milk yield, milk composition and body condition score. Therefore, it is concluded that in crossbred cows in late lactation, with low levels of production, feeding UIP at levels higher than NRC (1989) recommendations is not required.