Effect of feeding protein according to ARC and NRC recommendations on dry matter intake, digestibility and production performance in crossbred cows in late lactation

The effect of feeding protein according to the ARC (1984)and NRC (1989)recommendations on dry matter intake, digestibility, N balance, milk yield and milk composition was studied in crossbred dairy cows in late lactation. The study included a feeding trial and a metabolism trial. The feeding trial was conducted using eight multiparous cows in late lactation in a switch over design. The cows were divided into two groups of four cows. Group I (Gp I) received an ARC protein diet and Group II (Gp II) an NRC protein diet. The duration of the trial was fourteen weeks, each period lasting for seven weeks. The diet consisted of mixed straw of finger millet and paddy (FM-P) and a compound feed mixture (CFM). The roughage dry matter intake for Gp I and Gp II was 3.87 and 3.69 kg d−1, respectively. The 4% FCM yield (kg d−1) for the corresponding two groups was 6.44 and 6.75. The fat, SNF and protein contents (%) for Gp I and Gp II were, respectively 4.69, 8.82, 3.93 and 4.95, 9.04, 4.28. The difference between the two groups in roughage DMI, body condition score, milk yield and milk composition was not significant (P>0.05). The DOMD of the two diets was similar. However, N balance (g d−1) in Gp II (39) was significantly (P<0.01) higher than in Gp I (4). The results indicated that although N balance improved with feeding higher UDP level according to NRC, 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 protein according to the ARC recommendations is adequate.