The objectives of this study were to evaluate the growth rates, carcass quality, shelf-life, tenderness, sensory characteristics, volatile compounds, and fatty acid composition of wool, hair, and composite (wool × hair) lambs. Twenty-one wether lambs [wool (Suffolk × Polypay/Targhee; n = 7), hair (Dorper × Dorper; n = 7), and composite (Dorper × Polypay/Targhee; n = 7)] were fed from weaning to finishing at the University of Idaho Sheep Center and subsequently harvested under United States Department of Agriculture inspection at the University of Idaho Meat Lab. At 48 h postmortem, carcass measurements were taken to determine the percent boneless closely trimmed retail cuts, yield grade, and quality grade. Loins were fabricated from each carcass and wet-aged at 0°C until 10-d postmortem. Following aging, 2.54-cm bone-in loin chops were cut and randomly assigned to 4 d of retail display, Warner-Bratzler Shear Force (WBSF), or sensory analyses. Thiobarbituric acid reactive substances were analyzed on days 0 and 4 of retail display while subjective and objective color measurements were observed once daily. Samples (24 g) were also collected for volatile compound and fatty acid analysis. A mixed model analysis of variance was used to assess breed differences. Discernable effects were considered at P < 0.05. Wool lambs had heavier hot carcass weights (P < 0.001), larger rib-eye area (P = 0.015), and higher dressing percent (P < 0.001) than the other breeds. There was an interaction observed between breed and days of retail display for browning (P = 0.006). On day 1 chops from the composite breed had more browning than chops from the wool breed. No differences were observed between groups for lean muscle L* values (P = 0.432), a* values (P = 0.757), and b* values (P = 0.615). Differences were not observed in lipid oxidation (P = 0.159), WBSF (P = 0.540), or consumer acceptability (P = 0.295). There were differences found for 7 of the 45 fatty acids detected and in 3 of the 67 volatile compounds detected. In conclusion, wool lambs were heavier and had a greater carcass yield than the hair lamb carcasses. Regardless of breed, consumers did not detect sensory traits that would impact their eating experience.
Keywords: color; fatty acids; flavor; hair sheep; lamb; wool sheep.
The U.S. lamb industry has been steadily losing production operations since the 1990s due to a decline in lamb consumption, caused by consumer flavor preferences, an increase in synthetic fabrics, and importation from Australia and New Zealand. This has limited the overall need for U.S. producers. The focus of this research was to evaluate the differences among wool, hair, and composite groups of lamb for growth traits, carcass characteristics, shelf-life stability, consumer flavor, volatile compounds, and fatty acid profiling. The study found the wool group maintained a higher overall weight, as well as a taller shoulder height, and heart girth circumference over the hair group. The wool group also had a superior final carcass size; however, the quality grade did not differ between the composite and wool groups. There was no difference between groups for consumer sensory levels or cook loss. Minimal variation was shown throughout the retail shelf-life; however, general discoloration increased as expected during retail display. Tenderness levels between groups were also similar. Volatile compounds showed differences for three compounds with variation between groups. Fatty acid analysis also determined seven compounds of interest; however, common fatty acids known to be flavor factors were not different between groups.
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