| Popis: |
Our objective was to determine the effects of dietary quality and protein supplementation of a low-quality warm-season hay on energy metabolism and methane emissions of beef steers.Eight cross-bred steers were used in a respiration calorimetry study with a replicated 4 × 4 Latin square design. Experimental diets were (1) a low-quality forage-based diet (7.4% CP, 66.6% NDF); (2) a low-quality forage with supplemental cottonseed meal (10.0% CP, 66.3% NDF); (3) a medium-quality forage-based diet (10.5% CP, 65.0% NDF); and 4) a high-quality forage-based diet (13.0% CP, 58.4% NDF). Diets were based on bluestem (Bothriochloa ischaemum) hay cut at 2 stages of maturity.Organic matter, fiber, energy, and protein digestibility and energy retention increased (P < 0.05) as the quality of the forage-based diets increased. Total methane production was not affected by diet, but methane production per unit of digested OM or energy retention decreased (P < 0.05) with increased diet quality. Protein supplementation of the low-quality grass hay increased (P < 0.05) DM, fiber, energy, and protein digestion but did not affect methane production. Methane production per unit of energy and protein retention decreased (P < 0.05) with protein supplementation. Enteric nitrous oxide emissions were minor and not affected by diet. An automated head chamber system gave average emission results similar to respiration chambers.Results demonstrate that protein supplementation of low-quality forage or increasing the quality of forage-based diets will potentially decrease the carbon-footprint of beef production. |
