Response of anestrous heifers fed local grass or oak foliage-based diet with two different mineral mixtures

The effect of incorporation of two different mineral mixtures and/or oak leaves was studied on nutrient utilization and reproductive performance in anestrous heifers. Twenty-one anestrous heifers (18.2 ± 1.45 months; 229 ± 14.2 kg body weight) were randomly distributed into three similar groups. Heifers in control (T₁) and first treatment group (T₂) were fed concentrate mixture incorporated with Bureau of Indian Standards (BIS) specific mineral mixture and a customized mineral mixture developed specially for Kumaon hills (MMKH), respectively, along with local green grass (Pennisetum orientale). In the second treatment group (T₃), concentrate mixture was the same as that of T₂, while the source of roughage was local oak (Quercus leucotricophora) leaves containing 3.35% condensed tannin. A digestibility trial was conducted after 120 days of study. The feed intake was similar among the groups. Digestibility coefficient of crude protein (CP) was lower in T₃ than T₂ and comparable to T₁. Feeding oak leaves improved absorption of calcium as compared to grass-fed animals. Bioavailability of copper and zinc was higher (P < 0.05) in oak leaves and MMKH fed group (T₃) as compared to T_1, but similar to T₂. Conversely, absorption of iron had the reverse trend and was reflected in serum Fe concentration. Hematological, biochemical, enzyme and hormonal profiles were not influenced by any of the treatments. The relative occurrence of estrus cyclicity and conception rate was more in groups T₂ and T_3, respectively, than other groups. It was concluded that feeding oak foliage-based diet containing 1.87% tannin along with customized mineral mixture developed for Kumaon hills improved certain nutrient utilization and reproductive performance as compared to local green grass supplemented with BIS-specific mineral mixture or MMKH.