Effect of Higher Dietary Protein and Energy Levels on Growth and Production Performance in Cross Bred Heifers

The study was undertaken to see the effect of feeding elevated levels of CP and TDN to crossbred calves up to conception age and during post-partum period on growth, productive and reproductive performance. Twelve crossbred calves (4.75±0.2 month age) divided into two equal groups were fed either as per NRC standards (T₁) or 10% CP and TDN above NRC (T₂) up to conception and then during post- partum lasting to 120 d. Dry matter per 100 kg body weight or per kg metabolic body size did not differ significantly during growth and heifer phase, however, DCP and TDN intake increased significantly (P<0.05) in experimental animals of treatment group T₂ as compared to T₁. The digestibility of CP, EE, OM and NFE were higher (P<0.05) in experimental animals fed higher protein and energy diet as compared to control during the digestion trials conducted at 12 months and 16 months ages of the calves. During growth period, body weight gain was significantly (P<0.05) higher in T₂ (604.38 g/d) than that of control group T₁ (504.77 g/d). Feed conversion efficiency was also better in calves and heifers fed higher plane of nutrition. The heifers maintained at higher levels of CP and TDN attained pubertal age by 73 days earlier than maintained on NRC feeding scale i.e. control, however, conception rate was not affected, though the total dry matter intake and cost of feeds up to conception was reduced in T₂ as compared to T₁. The first calving age of cows was reduced on feeding of elevated level of nutrients. During post –partum period, the average daily milk yield and FCM yield was significantly (P<0.05) higher in T₂ group than that in T₁. The peak yield being higher (P<0.5) in cattle fed higher levels of CP and TDN, though it took longer time to reach peak production. The first post – partum oestrus was observed earlier (P<0.05) in animals fed higher plane of nutrition. Henceforth, present findings concluded that feeding of 10% protein and energy above NRC feeding scale to crossbred calves increased growth rate, improved nutrient utilization and FCE, reduced puberty and first calving age, increased milk yield and the first post partum oestrus was exhibited earlier than the control group.