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Acta Prataculturae Sinica ›› 2024, Vol. 33 ›› Issue (3): 198-208.DOI: 10.11686/cyxb2023191

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Effect of different ratios of amino acids in low-protein diets on muscle quality, amino acid and fatty acid composition, and vitamin and mineral contents of the longissimus dorsi muscle in Tibetan sheep

Feng-shuo ZHANG(), Qiu-rong JI(), Ting-li HE, Qu-yang-ang-mao SU, Zhi-you WANG, Sheng-zhen HOU, lin-Sheng GUI()   

  1. College of Agriculture and Animal Husbandry,Qinghai University,Xining 810016,China
  • Received:2023-06-09 Revised:2023-07-21 Online:2024-03-20 Published:2023-12-27
  • Contact: lin-Sheng GUI

Abstract:

The aim of this experiment was to investigate the effects of different ratios of the amino acids lysine and methionine in low-protein diets on the muscle quality, amino acid and fatty acid composition, and vitamin and mineral contents of the longissimus dorsi muscle of Tibetan sheep. Ninety healthy male lambs of Tibetan sheep (plateau type) with similar body weight [(15.60±0.10) kg] were selected and randomly divided into three groups of 30. Each group had five replicates of six lambs. The protein level in the dietary concentrate was 12%, and the three groups were as follows: LP-L group (1∶1 lysine to methionine); LP-M group (2∶1 lysine to methionine); and LP-H group (3∶1 lysine to methionine). The total experimental period was 97 days, including a 7-day pre-feeding period and a 90-day feeding period. Analyses of the longissimus dorsi muscle showed that: 1) The thawing loss index was significantly lower in the LP-L group than in the LP-H group (P<0.05), and the cooking loss index and shear force index were significantly lower in the LP-L group than in the LP-M and LP-H groups (P<0.05); 2) The different amino acid ratios did not significantly affect the amino acid composition in the longissimus dorsi muscle of each group (P>0.05); 3) Among the unsaturated fatty acids in the longissimus dorsi muscle, trans-linoleic acid, docosahexatrienoic acid, and pentadecadienoic acid were present at significantly higher levels in the LP-L group than in the LP-M group (P<0.05); and heptadecadienoic acid, linoleic acid, and α-linoleic acid were present at significantly higher levels in the LP-L group than in the LP-M group and the LP-H group (P<0.05); 4) The α-vitamin E content, γ-vitamin E content, and vitamin E index of the longissimus dorsi muscle were significantly higher in the LP-L group than in the LP-M group (P<0.05), while the calcium content was significantly higher in the LP-L group than in the LP-M group (P<0.05). In conclusion, a diet with a 1∶1 ratio of lysine to methionine can increase the contents of unsaturated fatty acids, vitamins, and minerals in the muscle, thereby improving meat quality, and the ratio of lysine to methionine in the diet does not adversely affect the amino acid composition of the meat.

Key words: plateau-type Tibetan sheep, low protein, nutritional regulation, meat quality, amino acids, fatty acids, vitamins, minerals