Breed-specific responses to energy-rich diets: feed efficiency, nutrient utilization, and folliculogenesis in Sahiwal and crossbred heifers

Context Optimizing dietary energy supply is critical for enhancing growth efficiency and reproductive development in replacement heifers under practical farm conditions. Aims The current study offers information regarding the impacts of dietary energy inclusion on growth performance, nutrient digestibility, follicular development, as well as economics in Sahiwal and crossbred heifers. Methods A total of 24 heifers comprising 12 Sahiwal and 12 crossbred replacement heifers, aged 18 ± 2 months with a bodyweight of 250 ± 10 kg, were divided into a 2 × 3 factorial with four animals each over 42 days, including a 2-week adaptation period. Three isonitrogenous and calorie-dense total mixed rations were developed with 10%, 15% and 20% molasses. The data on weight gain, dry matter consumption, feed ratio, digestibility, and folliculogenesis was collected during the study. Experimental data were collected and analyzed using ANOVA in Minitab. Key results The results indicated that increased energy supplementation contributed majorly (P < 0.05) to increased dry matter intake, improved bodyweight gain, and nutrient utilization. Major differences in nutrient digestibility were found between breeds (P < 0.05). Moreover, folliculogenesis (P < 0.05) was positively affected by energy-rich diets, which showed the effect of reproductive readiness of growing heifers. Higher energy diets had an economic effect by increasing the total feed cost and cost per unit gain and decreasing the overall performance index. Conclusions Higher dietary energy improves biological performance and follicular development in heifers; however, excessive energy supply compromises feed efficiency and economic returns. Implications Moderate dietary energy levels appear most suitable for balancing growth, reproductive development, and economic efficiency in replacement heifers under practical farm management.