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PSXIV-17 Meat quality and fatty acid composition of lambs reared under thermal stress in grazing conditions and slaughtered at two body weights


 Interest in meat quality and its fatty acid composition stems mainly from the need to find ways to produce healthier meat. In Puerto Rico, no documented information is available on the nutritional profile in the meat of lambs raised under local conditions (crossbred animals raised in heat stress and grazing naturalized pastures, NP). The quality of meat and fatty acid composition was evaluated, of 12 lambs grazed NP > 8h, tropical grass hay and water ad libitum, 150g of concentrate (12% CP), and mineral blocks. Six animals were slaughtered at two live weight of 22 (SW1) or 35 (SW2) kg to determine the meat quality given by pH, color, nutrient content, and the fatty acid composition in the Longissimus dorsi muscle. The data was analyzed using a completely randomized design with two treatments and six repetitions. SW1 and SW2 had similar pH (5.57 vs. 5.73), but lambs at SW1 displayed lower (P < 0.01) a* value than those slaughtered at SW2 (11.18 vs 13.57), but L* (38.91 vs 37.56) and b* (10.72 vs 10.67) values were similar. On both slaughter weight moisture (75.63 vs 74.51), ash (4.10 vs 3.34), crude protein (24.36 vs 25.12), and crude fat (2.30 vs 2.01) percentage of the meat was similar. The total lipid content (0.953 vs 2.25), saturated fatty acids (34.68 vs 42.98), and monounsaturated fatty acid (28.36 vs 37.28) of lambs at SW1 was lower than those at SW2, but n-6 and n-3 polyunsaturated fatty acids (18.74 vs 8.57and 6.61 vs 2.88, respectively) were higher (P < 0.05). The n-6/n-3 ratio was similar for both SW groups (2.84 vs 2.96). Differences in individual fatty acid content due to the slaughter weight were observed. In conclusion, the meat quality and the fatty acid composition of the Longissimus dorsi were affected by slaughter weight of lambs grazing naturalized pastures.