Effect of different combinations of energy and protein in total mixed ration on digestibility of nutrients, nutritive value and nutritive intake in crossbred heifer calves

The experiment aimed to evaluate the impact of varying energy and protein levels in total mixed ration on digestibility of nutrients, nutritive value and nutritive intake in crossbred heifer calves. A total of twenty-four crossbred heifer calves (75% Holstein Friesian x 25% Kankrej) with similar growth rate, age, and body weight were randomly allocated to four treatment groups, each consisting of six calves. The calves in groups T1, T2, T3, and T4 were fed TMR having 12.60% Crude Protein (CP) & 2.028 Mcal Metabolizable Energy (ME)/kg feed, 14.30% CP & 2.131 Mcal ME/kg feed, 15.98% CP & 2.244 Mcal ME/kg feed, and 17.58% CP & 2.307 Mcal ME/kg feed, respectively, for 140 days. The digestibility (%) of DM, OM, CP, EE, NFE, NDF, and ADF of TMRs were non-significantly (p>0.05) different among treatments. The CF digestibility (%) of TMRs fed to crossbred heifer calves significantly (p<0.05) higher in T1 and T2 compared to T3 and T4. The DCP intake (kg/day, kg/100kg BW, g/kg W0.75) differed significantly (p<0.05) among the treatment groups, and it increased progressively from lowest T1 to highest T4. The DEE and DNFE intake (kg/day, kg/100kg BW, g/kg W0.75) was significantly (p<0.05) higher in high ME, CP group (T3, T4) than low ME, CP group (T1, T2). The daily energy (AME, ATDN) intake as significantly (p<0.05) higher in high ME, CP group (T4) than in ME, CP group (T1, T2, T3). The percent and metabolic body weight basis AME and Actual TDN intake were significantly (p<0.05) higher in high ME, CP group (T3, T4) followed by T2 and lowest reported in the T1 group.