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The objective of this experiment was to compare the effects of dietary supplementation with cooking grease recovered from rinse-trap water lines (rinse-trap grease; RTG) versus conventional supplemental fats (tallow; TL, and yellow grease; YG) on 84-d growth performance, dietary energy, and carcass traits of feedlot lambs. Forty-eight Pelibuey × Katahdin lambs (27.7 ± 3.4 kg) were assigned in a randomized complete block design to evaluate: 1) basal diet without supplemental fat (Control); 2) 4% TL; 3) 4% YG, and 4) 4% RTG. Supplemental fats replaced maize in the control diet. Rinse-trap grease contained greater moisture (16.5 vs 0.92%) and impurities (3.6 vs 0.56%), and less total fatty acid (64.90 vs 89.60%) than that of conventional fats (TL and YG). Daily weight gain and gain efficiency were similar for control and RTG supplemental lambs, whereas ADG and gain efficiency were greater for lambs fed conventional fats than control or RTG-supplemented lambs. Both dietary net energy (NE) as well as ratio of observed-to-expected dietary NE were 4% greater for lambs supplemented with conventional fats vs RTG. Supplemental fat increased fat deposition but did not affect any other carcass measures or non-fat visceral mass. Estimated NE value for RTG was 57% of the average NE value (6.11 Mcal/kg) of tested conventional fats. Supplementation with RTG does not affect diet acceptability, and accordingly, is a suitable energy source for feedlot lambs. However, due to its lower total fatty acid content, its energy value is much lower than conventional supplemental fats. [ABSTRACT FROM AUTHOR]

The aim of this trial was to test the effects of the use of eubiotics (pro- and prebiotics) alone or in combination in the diet of lambs finished under subtropical climate conditions. For this purpose, 40 Pelibuey × Katahdin lambs (29.5 ± 4.8 kg initial live weight) were used in a 93 day growth-performance experiment. Dietary treatments consisted of a cracked corn-based finishing diet supplemented with (1) no eubiotics (control), (2) 3 g of probiotics (live Saccharomyces cerevisiae , SC), (3) 3 g of prebiotics (mannan oligosaccharide plus b-glucans, MOS), and (4) a combination of 1.5 g of SC and 1.5 g of MOS (SC+MOS). Throughout the study, the average temperature humidity index (THI) was 78.60. Compared to controls, supplementation with SC or MOS, alone did not affect average daily gain (ADG), but enhanced feed efficiency by 5.6% and 6.9% (gain-to-feed ratio, G:F) and dietary net energy by 4.6% and 5.9%, respectively. Compared to controls, SC+MOS enhanced ADG (10%), G:F (9.5%), and dietary net energy (7.2%). Lambs fed SC+MOS had also greater ADG, G:F, and dietary net energy compared to lambs fed SC alone. When compared to MOS, the combination enhanced ADG (10.4%, p = 0.04). This effect could be attributed to the increased dry matter intake (7.6%, p = 0.06), as neither G:F nor dietary energy was significantly affected. Compared with controls and SC, supplementation with MOS alone and SC+MOS increased kidney-pelvic-heart fat, while SC supplementation tended ( p = 0.08) to reduce 4.1% the relative intestinal mass (as a proportion of empty body weight) when compared to controls. Treatment effects on the other carcass measures were not significant. In the present study, supplemental probiotics and/or prebiotics improved dietary energetic efficiency in lambs finished under subtropical climatic conditions. The combination of probiotics with prebiotics reinforced this positive effect.