Influence of Varying Ruminally Degradable to Undegradable Protein Ratio on Nutrient Intake, Milk Yield, Nitrogen Balance, Conception Rate and Days Open in Early Lactating Nili-Ravi Buffaloes (Bubalus bubalis)

Mahr-Un- Nisa,A Javaid,M Sarwar,M Aasif Shahzad

doi:10.5713/ajas.2008.70565

Abstract

Twenty four early lactating Nili-Ravi buffaloes, eight in each group, were used in a Randomized Complete Block Design to evaluate the influence of varying ruminally degradable protein (RDP) to ruminally undegradable protein (RUP) ratio on feed intake, digestibility, N balance, milk yield and its composition, conception rate and days open. Three experimental diets were formulated to contain RDP:RUP of 50:50, 66:34 and 82:18 and were denoted as HRUP, MRUP and LRUP, respectively. Dry matter (DM) intake was higher (p<0.05) in buffaloes fed HRUP diet than in those fed MRUP and LRUP diets. Dry matter digestibility was higher (p<0.05) in buffaloes fed LRUP diet than in those fed HRUP and MRUP diets. Linear increase was observed in DM digestibility with increasing RDP:RUP while Neutral detergent fiber digestibility remained unaltered in buffaloes fed HRUP and MRUP diets, however, it was higher than in those fed LRUP diet. Crude protein digestibility remained unaltered across all treatments. Milk and 4 percent fat corrected milk (4% FCM) yield was higher (p<0.05) in buffaloes fed HRUP diet than those fed MRUP and LRUP diets. Linear decrease in milk yield was observed with increased RDP:RUP. Milk protein and fat yields were higher (p<0.05) in animals fed HRUP diet than those fed MRUP and LRUP diets. Milk protein percent in animals fed HRUP diet was higher than in those fed LRUP diet, whereas it did not differ with those fed MRUP diet. Percent of fat, total solids, solid not fat and lactose remained unaltered across all diets. Nitrogen balance was higher in buffaloes fed HRUP diet than in those fed other diets. Increasing the RDP:RUP resulted in a linear decrease in N balance. The blood urea nitrogen and milk urea nitrogen were lower (p<0.05) in buffaloes fed HRUP diet than those fed MRUP and LRUP diets. The blood pH remained unaltered across all treatments. Days open did not differ significantly. Conception rate was higher in buffaloes fed HRUP diet than those fed MRUP and LRUP diets. The findings of the present study indicate that feeding high (50% of the total crude protein) ruminally undegradable protein diet not only increased nutrient intake and milk yield but also improved conception rate in early lactating buffaloes.

Highlights

Protein is one of the limiting nutrients in the diet of dairy animals in developing countries (Sarwar et al, 2002)
During the last 25 years, the trend has been shifted from balancing rations for crude protein (CP) to balancing for ruminally degradable protein (RDP) and ruminally undegradable protein (RUP) fractions (Eastridge, 2006)
Statistical analysis The data collected on dry matter intake (DMI), digestibility, milk yield, milk composition, Milk urea nitrogen (MUN), Blood urea nitrogen (BUN), blood pH and N balance were subjected to ANOVA using the general linear model procedure of SPSS (SPSS 10.0.1., 1999)

Summary

INTRODUCTION

Protein is one of the limiting nutrients in the diet of dairy animals in developing countries (Sarwar et al, 2002). Adequate protein supply becomes very important in early lactating buffaloes when dry matter intake (DMI) is relatively low and protein and energy requirements are high (Sarwar et al, 2004a; Shahzad et al, 2008). Imbalance of RDP and RUP in a ruminant diet can compromise the microbial protein production, ruminal digestion and protein availability to dairy animals, if RDP is insufficient to meet microbial need (Santos et al, 1998; Reynal and Broderick, 2005). Lactating dairy animals require amino acids for milk production. N balance, milk yield and its composition, days open and conception rate in early lactating buffaloes

MATERIALS AND METHODS

RESULTS

DISCUSSION