Effects of Dietary Replacement of Alfalfa Hay With Corn Silage on Energy Utilization Efficiency and Metabolizable Energy Requirements in Crossbred Hu Ewes During Early Lactation

Abstract

We evaluated the effect of dietary substituting corn silage (CS) for alfalfa hay (AH) on feed intake, lactation performance, and energy utilization efficiency of crossbred Hu ewes. In a completely randomized experiment, 12 lactating crossbred ewes (3 ± 1.5 DIM) were fed one of three isoenergetic diets with forage-to-concentrate ratio of 70:30. The three experimental diets (CON, CS1, and CS2) were formulated by replacing AH with different levels of CS (0%, 30%, and 60%, respectively). Energy balance was determined through a metabolism and respiration trial. We observed identical trends for feed intake and gross energy intake (GEI); the GEI ranged from 0.97 to 1.34 (MJ/kg BW^0.75 day) among the treatments. Around 26%–33% of the GEI was lost as feces, 56%–60% for heat production, 14%–16% for milk production, 5%–6% for methane emission, and 3% for urinary energy. The metabolizable energy requirement for maintenance of crossbred Hu ewe was estimated to be 484.7 kJ/kg body weight^0.75/day. Furthermore, the energy digestibility and metabolizability of the CS diets were significantly greater than those of the CON diet. Substituting AH for up to 60% CS increased energy utilization efficiency without detrimental effects on milk production in crossbred Hu ewes fed a forage-based diet.