Effect of Energy Source, Level, Sex, and Age on Meat Characteristics of Lambs

The objective of the study was to compare ad libitum whole shelled corn (WSC; AC), 85% of ad libitum WSC (LC), and ad libitum alfalfa pellets (AA), lamb sex, and age, on meat characteristics. Ewe (n=48) and wether (n=48) lambs were blocked by sex and age, and stratified by initial weight to pen. Typical market age (TM) ewe (n=24) and wether (n=24) lambs were removed from the study when pens reached an average weight of 59.0 and 63.5 kg, respectively. The remaining long-fed ewe (n=24) and wether (n=24) lambs remained on feed for an average of 218 days total, then were removed from the study on a pen basis. Statistical analysis was conducted using PROC MIXED statement in SAS with diet, sex, age, and two- and three-way interactions as fixed effects, diet, sex, and age nested within pen as the random effect, with significance established at P < 0.05. There was an age × sex interaction (P < 0.05) for the ultimate pH of the Longissimus dorsi from lambs. Ultimate pH of the Longissimus dorsi was greater from TM ewe lambs compared with TM wether lambs and long-fed ewe lambs, and tended to be greater compared with long-fed wether lambs. Loin Minolta L* values were greater (P < 0.05) from TM lambs compared with long-fed lambs. There was a diet × sex interaction (P < 0.05) for lean Minolta a* values indicating wethers offered AC or AA had a greater lean Minolta a* value compared with ewes offered AC and wethers offered LC. Wethers tended (P = 0.06) to have a greater lean Minolta b* value when compared with ewe lambs. Minolta L* measurements of fat over the rack were greater (P < 0.05) from long-fed lambs compared with TM lambs. Minolta a* values of carcass fat were greater (P < 0.05) for AC lambs compared with fat from AA lambs, with LC lambs being intermediate. The total lipid percent in the Longissimus dorsi and ground shoulder patty was greater (P < 0.01) for long-fed lambs compared with TM lambs. Ground shoulder patties from lambs offered AC had a greater (P < 0.05) percentage of total lipid compared with lambs offered LC or AA. Long-fed lambs produced fatter carcasses with darker lean and brighter colored fat, and a lower ultimate pH. Lambs offered AC produced fatter carcasses with redder colored fat compared with AA and LC lambs.