Nutritional evaluation of four oat varieties and their potential for yak feeding in Gonghe County, Qinghai Province

The yak is an important domestic animal on the Tibetan Plateau, as it provides important living materials and an economic resource for the people in that region. As an important pasture species, oat plays an important role in the development of animal husbandry on the Tibetan Plateau. The aim of this study was to choose oat varieties with high forage quality and suitability for yak feeding. A comprehensive evaluation of the feeding value of four Avena sativa varieties (‘Qingyan No. 4’, ‘Qingyan No. 3’, ‘Longyan No. 1’, and ‘Baiyan No. 7’) was performed using yield indices, conventional nutritional indices, and in vitro gas production indices. The findings indicated that ‘Qingyan No. 4’ and ‘Qingyan No. 3’ had significantly higher fresh weight, hay weight, and nutrient output per unit than ‘Longyan No. 1’ and ‘Baiyan No. 7’, and ‘Qingyan No. 4’ showed the highest fresh grass yield and hay yield, and fresh weight of ‘Qingyan No. 4’ was 10.88% higher than that of ‘Longyan No. 1’, which had the lowest yield. There were no significant differences in crude protein, crude ash, or acid detergent fiber content among the four species of oats. Crude fat was significantly higher in ‘Qingyan No. 4’ and ‘Qingyan No. 3’ than in ‘Baiyan No. 7’, and ‘Qingyan No. 4’ had the highest content, which was 14.13% higher than that of ‘Baiyan No. 7’, which had the lowest content. ‘Baiyan No. 7’ had significantly higher neutral detergent fiber content than the other three cultivated oat species. and the content was 10.61% in ‘Baiyan No. 7’ than ‘Qingyan No. 3’, which had the lowest content. ‘Longyan No. 1’ produced significantly more gas than ‘Baiyan No. 7’ by 34.19%, while ‘Baiyan No. 7’ had a significantly higher pH than ‘Qingyan No. 3’. For volatile fatty acids, ‘Qingyan No. 3’ and ‘Longyan No. 1’ produced significantly more isobutyric acid than ‘Baiyan No. 7’; ‘Qingyan No. 3’ produced significantly more butyric acid than ‘Qingyan No. 4’ and ‘Baiyan No. 7’; ‘Longyan No. 1’ produced significantly more isovaleric acid than ‘Baiyan No. 7’; and ‘Longyan No. 1’ produced significantly more valeric acid than the other three oat varieties. ‘Longyan No. 1’ demonstrated significantly greater in vitro dry matter digestibility at 47.48% than the other three groups, while ‘Baiyan No. 7’ showed the lowest value at 35.28%. ‘Longyan No. 1’ showed significantly higher metabolic energy than ‘Qingyan No. 3’ by 13.31%. In summary, ‘Longyan No. 1’ exhibited superior performance in terms of yield, conventional nutritional indices, and gas production indices, making it a valuable roughage feed for yaks in the Gonghe County area of Qinghai Province.