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Acta Prataculturae Sinica ›› 2023, Vol. 32 ›› Issue (11): 130-139.DOI: 10.11686/cyxb2023030

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Distribution of sodium, potassium, and magnesium in 70-100 kg yak calves and the growth requirements for these nutrients

Jia-yu DUAN1(), Bo ZHANG1(), Jun CAO1, Shu-jie LIU1, Zhan-hong CUI2()   

  1. 1.Ministry of Agriculture and Rural Affairs Key Laboratory of Animal Nutrition and Forage-Feed of Grazing Yak and Tibetan Sheep in Qinghai-Tibetan Plateau,Key Laboratory of Plateau Grazing Animal Nutrition and Feed Science of Qinghai Province,Yak Engineering Technology Research Center of Qinghai Province,Qinghai Academy of Animal Husbandry and Veterinary Sciences in Qinghai University,Xining 810016,China
    2.Haibei Tibetan Autonomous Prefecture Plateau Ecological Animal Husbandry Science and Technology Demonstration Park Management Committee,Haibei 810299,China
  • Received:2023-02-01 Revised:2023-03-15 Online:2023-11-20 Published:2023-09-27
  • Contact: Zhan-hong CUI

Abstract:

The aim of this work was to explore the distribution of sodium, potassium, and magnesium in 70-100 kg yak calves, and to determine the growth requirements for these minerals in these calves. A 75-day experiment consisting of a 15-day pre-feeding period and a 60-day positive-feeding period was conducted from November 2020 to January 2021. Twenty-one yak calves (male) with good body condition and similar body weight [average, (60.44±4.59) kg] were selected and randomly divided into three groups; The initial slaughter group (BL group), the middle slaughter group (M group), and the final slaughter group (F group). The three groups of calves were fed the same kind of feed, ad libitum, during the pre-feeding period of 15 days and the 60-day positive feeding period. The calves in the BL, M, and F groups were slaughtered at the end of the pre-feeding period, mid-way through the positive-feeding period, and at the end of the positive-feeding period, respectively. At slaughter, the average weight of calves in the BL, M, and F groups was 73.61, 81.96, and 96.53 kg, respectively. After slaughtering the calves, tissue samples were collected and weighed. The contents of sodium, potassium, and magnesium in the tissues were determined, and the distribution patterns of these minerals in the calf body were analyzed. A mathematical model was established to predict the growth requirements for these minerals in yak calves. It was found that: 1) The meat weight, viscera (including blood) weight, tare weight, and gross weight all increased significantly (P<0.05) with increasing body weight of yak calves. The bone weight and fat weight were significantly higher in the F group than in the other two groups (P<0.05). During the experiment, the bone growth rate decreased, while the muscle growth rate showed an increasing trend. 2) More potassium was distributed in muscle than in fat; And more sodium and magnesium were distributed in bones than in other tissues. A small amount of magnesium was distributed in fat and hair. 3) The sodium and potassium contents were higher in the F group than in the other two groups. On an empty (fasting) body weight (EBW) basis, the formulae approximating the nutrient requirements for gain (NRG) for sodium, potassium and magnesium were, respectively NRG=1.0125×EBW-0.0807NRG=0.8810×EBW0.2650, and NRG=0.04567×EBW0.5209. These results show that, for 70-100 kg yak calves, the NRGs for sodium, potassium, and magnesium are 0.73-0.74 g·kg-1 EBW, 2.49-2.65 g·kg-1 EBW, and 0.35-0.40 g·kg-1 EBW, respectively.

Key words: yak calves, sodium, potassium, magnesium, distribution law, growth requirements