Sonali Prusty

Nutrient utilisation, growth performance and blood metabolites in Murrah buffalo calves (Bubalus bubalis) divergently selected for residual feed intake

ABSTRACT The aim of this study was to evaluate differences in efficiency of feed utilisation between buffalo calves with low and high residual feed intake (RFI) by comparing feed intake, nutrient digestibility, growth traits and blood metabolites. Eighteen male Murrah buffalo calves (aged 4–6 months; 70 ± 1.0 kg body weight) were fed ad libitum with a total mixed ration for 120 d. Based on linear regression models involving dry matter intake (DMI), average daily gain (ADG) and mid-test metabolic body size, calves were assigned into low and high RFI groups. The RFI varied from −0.33 to +0.28 kg DM/d with an average RFI of −0.14 and 0.14 kg DM/d in low and high RFI calves, respectively. Calves had a mean DMI of 1.9 and 2.4 kg/d and an ADG of 0.5 and 0.6 kg/d in low and high RFI groups, respectively. Low RFI calves ate 19.0% less DM each day and required significantly less metabolisable energy for maintenance compared with high RFI calves (12.5 vs. 16.7 MJ/d). Nutrient digestibility and nitrogen balance did not differ among low and high RFI calves. In more efficient animals (low RFI calves) higher (p < 0.05) plasma level of growth hormone, insulin-like growth factor-1 (IGF-1), triiodothyronine (T3) and lower concentration of thyroxin hormone were detected. No significant differences in levels of insulin, hydroxyproline, plasma and urine creatinine, total protein and albumin between high and low RFI groups were found. Blood metabolites showed significant (p < 0.05) differences at initial and final stages of study in both groups. At final stage of study, RFI showed negative correlations with growth hormone, IGF-1, T3, urine creatinine and albumin. Low RFI buffalo calves are more efficient in feed utilisation and the differences in blood metabolites are probably due to differences in feed intake and body metabolism.

Metabolizable Protein Requirements of Lactating Murrah Buffaloes (Bubalus bubalis) Fed on Silage Based Diets

The aim of present study was to determine the metabolizable protein (MP) requirements of lactating buffaloes fed on silage based diet. Fifteen lactating Murrah buffaloes (Bubalus bubalis) were allocated into three treatments (n=5) on the basis of milk production (7.10±0.40) and days in milk (118±5.0 d). The nutrient requirements of buffaloes were met by feeding maize silage: concentrate mixture in proportion of 60: 40 for a period of 96 days. The MP level in second treatment (Control; 11.1% on DM basis) was provided as per ICAR (2013) standards whereas in treatment one and three, MP levels were 10% lower (10% LMP) and 10% higher (10% HMP), respectively than ICAR (2013) requirements. Feeding of diets containing varying levels of MP did not affect body weight, milk production and milk composition, urinary levels of purine derivatives and microbial N production. The N intake and N excretion showed positive correlation with dietary MP content and reported highest (P<0.05) in 10% HMP fed buffaloes. The estimated MP requirement for maintenance plus 6% fat corrected milk yield (6% FCM) in experimental buffaloes were 2.56 g/kg W0.75 and 66.78 g/kg, respectively. The estimated MP requirements for maintenance and 6% FCM were 3.11% lower and 1.13% higher than recommendation of ICAR (2013), respectively. In conclusion, performance of lactating buffaloes was not affected by feeding diets containing 10% higher or 10% lesser MP than ICAR (2013) recommendation. As per current study, ICAR (2013) recommendation can be used for feeding lactating buffaloes.

‘Omics’ Approaches to Understand and Manipulate Rumen Microbial Function

Diverse populations of rumen microorganisms in gut contribute to develop ability of breaking down fibrous foods, which are mostly unusable by humans (Owens FN, Goetsch AL (1988) Ruminal fermentation. In: Church DC (ed) The ruminant animal, digestive physiology and nutrition. Prentice-Hall, Englewood Cliffs, p 160). Rumen is having a larger population of microorganisms, more than a trillion organisms and wide diversity (hundreds of species and thousands of subspecies), per ounce of rumen contents (Xu et al., J Anim Sci 85:1024–1029, 2007). There are various traditional approaches through which overall performance of the rumen has been attempted to improve, e.g. plant secondary metabolites, microbial feed additives, chemical feed additives, selective stimulation of beneficial rumen microbes and selective inhibition of harmful rumen microbes. In spite of these, nowadays various new approaches are being used to improve our understanding of the relationships among the various rumen microorganisms and towards how they interact with their hosts (Chaucheyras-Durand and Ossa, Prof Anim Sci 30:1–12, 2014). To better characterize species in the rumen, new advanced technological aids such as gene sequencing and study of gene (genomics), protein (proteomics) and metabolite (metabolomics) expression are being frequently used. This chapter will majorly emphasize on recent tools used in exploring the diversity of rumen.