Rumen and liver measurements of lambs fed with high inclusions of crude glycerin in adaptation and finishing period of feedlot

Crude glycerin is the main by-product of biodiesel industry and has great potential for reducing the feed costs in ruminant feedlot systems without affecting animal health and performance, mainly as a replacement for corn grain. The objective of this study was to evaluate the effects of increasing inclusions of crude glycerin (up to 30%) in diets for crossbred feedlot lambs in two different periods (adaptation and finishing) on the rumen morphometric and liver variables. Fifty-five 3-month-old crossbred lambs were randomly allocated in individual pens indoors, assigned to a complete randomized block design and fed with four experimental diets, containing 0, 10, 20 or 30% crude glycerin. Three animals were slaughtered at the end of the pre-adaptation period (d0), twelve at the end of the adaptation period (d14), and the remaining (n = 40) when they reached approximately 35 kg BW. After slaughtered, the stomach compartments and liver were collected and evaluated. All stomach compartments, number of rumen papillae and mitotic index were higher for the finishing period (P < 0.05). Crude glycerin treatments showed greater rumen weights when compared to control treatment (G0 vs G, P = 0.01) in the finishing period. The increasing inclusion of up to 30% of crude glycerin/kg DM in diets for crossbred lambs did not compromise the stomach compartments and rumen papillae measurements in both periods of the feedlot. No clinical manifestations resulted from ruminal acidosis (such as liver abscess, ruminitis, and lesions in the ruminal mucosa) were observed in any period and treatment studied. Thus, we conclude that the replacement of corn cracked grain by crude glycerin (up to 30% DM) was effective in the animals' adaptation to concentrate-based diets.