Abstract
Twenty-four Dorper x Pelibuey lambs were housed in individual pens during a 31-d feeding period and assigned to four treatments (n = 6) under a randomized complete block design with different daily doses of zilpaterol hydrochloride (ZH): 0 (control), 0.1, 0.2, and 0.3 mg/kg BW to determine the effects of ZH supplementation on productive performance, meat quality, and wholesale cut yields. Final BW (p = 0.02) and average daily gain (ADG, p = 0.04) were greater in lambs supplemented with 0.2 mg/kg BW. Supplemental ZH tended to improve dry matter intake (DMI, p = 0.008) and ADG:DMI ratio (p = 0.078). Wholesale cut yields were not affected by ZH supplementation. Percentage of head was greater (p = 0.04) in lambs treated with ZH. The ZH supplementation did not affect carcass characteristics. However, longissimus thoracis et lumborum (LTL) presented a linear trend (p = 0.08) of increasing with ZH supplementation. Percentage of blood presented a trend (p = 0.051) of decreasing with ZH supplementation. Also, liver decreased in size (p < 0.05) for treatments where ZH was included. Values of luminosity decreased (p < 0.02) when ZH dosage increased. The value of protein Lowry was greater, with 0.3 mg kg−1 (p = 0.04). Cathepsin B + L was greater in the lambs from the control treatment (p = 0.05). In conclusion, using a daily ZH dosage of 0.2 mg per kg of BW produced the best productive performance, carcass characteristics, and some changes in the meat of hair-breed lambs.
Highlights
During the last decade, the number of hair breeds of lambs has increased in several Latin American countries because of their ease of management and resistance to parasites [1]
Aguilera et al [22] and Pringle et al [23] reported a significant improvement in average daily gain (ADG) during the first 2 weeks after administration of the β-adrenergic agonists (β-AA) zilpaterol hydrochloride (ZH) (6 ppm) and RH (4 ppm), respectively, with no response in the subsequent weeks
A fast fall in meat pH during the first 45 min postmortem is associated with a low capacity for water retention and tenderness, whereas a pH greater than 6.0 after 24 h postmortem is associated with dark, firm, and dry meat. These results suggest that this β-AA negatively affected meat quality of ram lambs due to alterations of the normal decrease in the pH during the first 24 h after slaughter
Summary
The number of hair breeds of lambs has increased in several Latin American countries because of their ease of management and resistance to parasites [1]. Lambs from those breeds have a lower growth rate, carcass yield, and meat quality compared with lambs from wool breeds [2]. Agriculture 2020, 10, 241 and efficient growth of livestock, and improve the carcass yield, i.e., increasing longissimus thoracis et lumborum (LTL) muscle area [3] or diminishing the fat content in the carcass [4]. Use of growth promoters, such as β-adrenergic agonists (β-AA), may improve growth and carcass characteristics of lambs from hair breeds. Zilpaterol hydrochloride (ZH) is a β-adrenergic repartition agent that has been shown to enhance carcass leanness, improve growth rate, and decrease feed consumption in cattle [6] and lambs [7]
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