青海省科技厅自然科学基金青年项目（2022-ZJ-934Q）, 青海大学青年科研基金（2021-QNY-8）, 青海省科技厅科技成果转化专项（2018-NK-107）和青海省科技厅科技援青合作专项（2020-QY-217）共同资助。
为了研究裂殖壶藻饲喂对牦牛生长性能的影响，将24头2～3岁健康雄性牦牛分为对照组和微藻组，每组12头，对照组饲喂基础日粮，微藻组每天在基础日粮加入200 g·头-1的裂殖壶藻，进行为期60 d的饲喂试验。试验期间记录两组牦牛日均采食量变化；测定两组牦牛饲喂前后体重和体尺指标变化；ELISA检测血清生长激素（GH）、三碘甲状腺原氨酸（T3）和甲状腺素（T4）变化规律；饲喂结束后进行屠宰，分离器官和组织计算屠宰率；同时荧光定量PCR（qPCR）和蛋白免疫印迹（WB）检测试验60 d后两组牛体内生长相关因子表达变化，探究裂殖壶藻饲喂影响牦牛生长性能的作用机制。结果表明，与对照组相比，裂殖壶藻饲喂后，牦牛体重、胸围和屠宰率显著增加（P < 0.05），血清生长相关激素GH、T3和T4含量均显著增加（P < 0.01），生长相关基因（Ampkα1、Mc4r、Lxrα、Lkb1）和生长相关蛋白（AMPKα1）表达显著上调（P < 0.01）。综上所述，裂殖壶藻饲喂促进牦牛生长激素水平升高，调控牦牛生长相关因子表达，从而加快其生长发育和生长性能提升，为牦牛繁育和饲料改良提供了一定的理论依据。
In order to study the effect of Schizochytrium feeding on the growth performance in yaks, 24 healthy male yaks aged 2-3 years were divided into control group and microalgae group, with 12 in each group. The control group was fed with basic diet, and the microalgae group added 200 g·head-1 Schizochytrium to the basic diet every day for 60 days. During the experiment, the changes of daily average feed intake of yaks in two groups were recorded; The changes of body weight and body size were measured before and after feeding; Changes of serum Growth hormone (GH), Triiodothyronine (T3) and Thyroxine (T4) were detected and analyzed by ELISA. After feeding, the carcass percentage was calculated by separating organs and tissues; Fluorescence quantitative PCR (qPCR) and Western blotting (WB) were used to detect the expression changes of growth related factors in the two groups after 60 days, so as to explore the mechanism of Schizochytrium feeding on the growth performance in yaks. The results showed that, compared with control group, the body weight, chest circumference and slaughter rate were significantly increased (P < 0.05), the expression levels of serum growth related hormones GH, T3 and T4 were significantly increased (P < 0.01), and the growth related genes (Ampkα1, Mc4r, Lxrα, Lkb1) and growth related protein (AMPKα1) were significantly up-regulated (P < 0.01) after Schizochytrium feeding in yaks. In conclusion, Schizochytrium feeding increase the growth hormone levels, via regulates the expression of growth related factors and promotes their growth and development performance in yak, which provides a certain theoretical basis for yak breeding and feed improvement.