Enhancing lactation performance and energy utilisation efficiency through dietary inclusion of apple pomace silage and hempseed cake in dairy cows

Apple pomace (AP) and hempseed cake (HC) are used for replacing conventional feed ingredients in dairy farming, but their effects on energy partitioning remains insufficiently explored. This study investigated the effects of dietary inclusion of AP silage and HC to mid-lactation dairy cows on lactation performance and energy utilisation efficiency. Fifteen dairy cows were used in a 3 (treatments) x 3 (Periods) Latin square design study. Treatment diets included (dry matter [DM] basis) (1) CON: basal diet containing 50.0% concentrates, 45.7% grass silage and 4.3% barley straw; (2) AP: 10% of AP replaced grass silage in the CON diet; (3) HC: 10% of HC replaced concentrates in the CON diet. Dietary inclusion of AP or HC significantly increased DM intake (DMI) by 6.7% and 3.4% (P = 0.001), milk yield by 8.8% and 11.3% (P < 0.001), compared with CON. Milk yield per unit of DMI was the highest in HC, followed by AP and CON (P =0.022). Crude protein digestibility was higher in AP than in CON group (P= 0.038). When compared with CON, both AP and HC tended to increase rumen propionate production (P = 0.082) and significantly decreased rumen acetate: propionate ratio (P= 0.040). Urinary and methane energy outputs and heat production as a proportion of gross energy intake (GEI) significantly decreased when diets were supplemented with AP and HC (P < 0.01), and inclusion of AP also increased retained energy as a proportion of GEI. Feeding AP and HC significantly decreased heat production/metabolisable energy (ME) intake by 10.7% and 7.6% respectively (P < 0.001). Higher efficiency of ME used for lactation was observed in AP and HC group, increasing by 4.3% and 7.7% respectively (P = 0.017), compared to CON. Overall, AP silage and HC are promising alternatives to high-quality grass silage and conventional protein feeds in dairy cow diets. These by-products can enhance the lactation performance and improve cow’s energy utilisation efficiency.