Abstract
Tibetan sheep is one of the dominant livestock at Qinghai-Tibet Plateau, which is the main food source of local people. In order to investigate the effect of slaughter age on meat quality, fatty acid profile and expression of myosin heavy chain (MyHC) isoform genes were analyzed in Tibetan sheep. A total of 24 Tibetan sheep including 4 months old (4 m), 1.5 years old (1.5 y), 3.5 years old (3.5 y), and 6 years old (6 y) were randomly selected. The results indicated that the MyHC IIx and MyHC IIb mRNAs increased with age, whereas MyHC IIa mRNA decreased. MyHC I mRNA was highest at 3.5 y. There were differences in the muscle fiber types of Tibetan sheep at different ages. Intramuscular fat (IMF) was highest at 1.5 y, the pH45min and pH24h value of 6 y sheep were lower than the other groups, the shear force increased with age (p < 0.05), and drip loss increased with age (p < 0.01). Tibetan sheep at 1.5 y had lower saturated fatty acid (SFA) contents and higher monounsaturated fatty acid (MUFA) contents (p < 0.05). Different muscle fiber types influence the meat quality and fatty acid composition of Tibetan sheep with increasing age. These results demonstrated the effect of age on meat quality of Tibetan sheep through regulation of expression of the MyHC isoforms which changed the myofiber types, and 1.5 y Tibetan sheep meat was more suitable for a healthy human diet.
Highlights
Consumers, especially from developed countries, are more health conscious and pay more attention to nutritional and physicochemical qualities of the meat products they consume [1]
Each muscle sample of Longissimus thoracis at the 12th and 13th rib was collected from the carcass immediately after slaughter; after rinsing with saline and de-RNAase water, RT-qPCR samples were collected in cryotubes and stored in liquid nitrogen immediately
The results of the present study indicated that the meat tenderness and water holding capacity of Tibetan sheep decreased with increasing age, Intramuscular fat (IMF) of 1.5 y Tibetan sheep was the highest
Summary
Especially from developed countries, are more health conscious and pay more attention to nutritional and physicochemical qualities of the meat products they consume [1]. Nutritional and physicochemical qualities are affected by various factors including the slaughter age [2], breed, sex, and diet of the animal [3]. Animal age is an important influencing factor that can affect both the meat quality and fatty acid profile [4]. The intramuscular fat (IMF) content accumulates with increasing age, improving water holding capacity and juiciness [5]. Abhijith et al have found that meat tenderness of boer goats decreased with increasing slaughter age [6].
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