Abstract
Simple SummaryThe Tibetan sheep (Ovis aries) is an ovine breed well adapted to the harsh plateau environment. For a long period of time, Tibetan sheep farming has been an important pillar industry for native herders on the Qinghai-Tibetan Plateau. With the increasing demand for sheep meat and products, nutrition research has gained increasing importance. In this study, the effects of three different dietary protein levels (10.1%, 12.1%, and 14.1%) on growth performance, carcass traits, serum metabolites, and meat composition were investigated in Tibetan sheep during the cold season. The results showed that the diets containing 12.1% and 14.1% protein were better than a diet containing 10.1% protein for enhancing the growth performance, carcass performance, and meat products of the Tibetan sheep.Dietary protein is a critical nutrient that directly influences the health and production of livestock. Recent studies showed that protein supplements could enhance the growth performance of Tibetan sheep. However, there is a lack of information regarding the influence of dietary protein levels on carcass traits and meat composition. This study investigated the effects of dietary protein levels on growth performance, carcass traits, serum metabolites, and meat composition in Tibetan sheep during the cold season on the Qinghai-Tibetan Plateau. A total of eighteen 1-year-old, healthy, castrated Tibetan sheep with similar initial body weights (31.7 ± 0.72 kg) were randomly divided into three treatment groups with different dietary protein level (low protein (LP, 10.1%); medium protein (MP, 12.1%); high protein (HP, 14.1%)) diets. The results indicated that the Tibetan sheep fed with the MP and HP diets had greater final body weights (BWs), average daily gains (ADGs), and average daily feed intakes (ADFIs) (p < 0.05). The MP and HP diets also improved the hot carcass weight, net meat (including the fat) weight, and bone weight of the sheep significantly (p < 0.05). Besides, the dietary protein levels could significantly affect the serum concentrations of growth hormone (p < 0.05). The diameter of muscle fibers in the MP group was significantly greater than that in the LP group (p < 0.05), while the density of muscle fibers showed the opposite trend. The dietary protein levels only significantly (p < 0.05) influenced the ether extract content and profile content of the longissimus dorsi muscle but had no effect on other parameters of meat composition. In summary, our results indicate that dietary protein levels affect growth performance, carcass traits, and meat composition and that diets containing 12.1% and 14.1% protein are recommended to obtain better production performance and meat products in Tibetan sheep, rather than a diet containing 10.1% protein, during the cold season on the Qinghai-Tibetan Plateau.
Highlights
The Qinghai-Tibetan Plateau (QTP) is a special ecosystem with an extreme environment, including a high altitude, a low temperature, and strong UV radiation [1,2]
feed/gain ratio (F/G) were significantly different between groups commencing during the last feeding stage (71–105 d), and the LP group had the lowest average daily gains (ADGs) and the greatest value of F/G (p < 0.05)
We found that the histological characteristics of the longissimus dorsi muscle fibers in Tibetan sheep could significantly affected by the dietary protein levels, and the diameter of muscle fibers was negatively correlated with density
Summary
The Qinghai-Tibetan Plateau (QTP) is a special ecosystem with an extreme environment, including a high altitude, a low temperature, and strong UV radiation [1,2]. During the warm season (June to October, average temperature approximately −2 to 12 ◦ C) sheep are largely dependent on natural grazing lands, but in the cold season (November to the following May, average temperature from approximately −5 to −15 ◦ C), the sheep are housed and fed in sheds to ensure normal growth [10]. Under this novel production system, the growth and development of sheep can be improved effectively. A better understanding of how to efficiently feed sheep would be beneficial for livestock production on the QTP
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