Performance and Ruminal Parameters of Boer Crossbred Goats Fed Diets that Contain Crude Glycerin

This study aimed to evaluate the effects of four levels of crude glycerin (0, 50, 100, or 150 g/kg on a dry matter basis) on intake, digestibility, production performance, and ruminal parameters for finishing Boer crossbred goats. Thirty-two crossbred, castrated Boer × undefined breed goat kids, with an initial average weight of 17.8 ± 2.2 kg and approximately four months old, were distributed in a completely randomized design, with four treatments and eight repetitions. The dry matter and neutral detergent fiber intakes, both in g/day and percent of body weight, linearly decreased (p ≤ 0.05) with increased inclusion levels of crude glycerin in the diet. The dietary crude glycerin levels linearly decreased (p ≤ 0.01) the digestibility coefficients of ether extract and quadratically increased (p = 0.04) digestibility coefficients of neutral detergent fiber. The final weight, total weight gain, and average daily gain for the animals showed a linear decrease (p ≤ 0.02) as dietary crude glycerin levels increased. The addition of crude glycerin caused a linear increase in ruminal pH (p ≤ 0.01), which ranged from 6.27 to 6.49 for diets with 0 and 150 g/kg crude glycerin, respectively. The concentration of ruminal NH₃-N exhibited a linear decrease as the crude glycerin inclusion levels increased (p ≤ 0.01). Total short-chain fatty acid (SCFA) concentration, individual molar ratio, and the acetate: Propionate ratio in the ruminal fluid of the animals were not influenced (p ≥ 0.07) by the dietary crude glycerin levels. These data indicate that crude glycerin should not be used to replace ground corn in the diets of growing goats that are finished in a feedlot because the substitution reduces the intake and digestibility of several nutrients and decreases performance.