In this study, we evaluated the roles of heat-induced circEZH2 in the regulation of milk fat metabolism. CircEZH2 overexpression increased HC11 cell proliferation and decreased apoptosis. These changes were accompanied by increased expression of proliferation marker proteins (PCNA, Cyclin D, and Cyclin E) and the anti-apoptotic protein Bcl2, while expression of the pro-apoptotic proteins Bax and cleaved-caspase was reduced. SiRNA-mediated silencing of EZH2 in HC11 cells had the opposite effects. CircEZH2 overexpression promoted the uptake of a fluorescent fatty acid (Bodipy) as well as expression of the fatty acid transport-related protein CD36, lipolysis-related protein LPL, and unsaturated fatty acid metabolism-related proteins FADS1 and SCD1. Dual luciferase reporter assays verified the targeting relationship of the two ceRNA networks, circEZH2-miR378b-LPL and circEZH2-miR378b-CD36. This information provides further clarification of the role of circRNAs in milk fat regulation in addition to a theoretical basis for alleviating the effects of heat stress on milk production by dairy cows.

This study compared the growth performance, serum biochemical indicators, rumen fermentation parameters, rumen bacterial structure, and fecal bacterial structure of cattle and yaks fed for two months and given a feed containing concentrate of a roughage ratio of 7:3 on a dry matter basis. Compared with cattle, yak showed better growth performance. The serum biochemical results showed that the albumin/globulin ratio in yak serum was significantly higher than that in cattle. Aspartate aminotransferase, indirect bilirubin, creatine kinase, lactate dehydrogenase, and total cholesterol were significantly lower in yaks than in cattle. The rumen pH, acetate to propionate ratio, and acetate were lower in yaks than in cattle, whereas the lactate in yaks was higher than in cattle. There were significant differences in the structure of ruminal as well as fecal bacteria between cattle and yaks. The prediction of rumen bacterial function showed that there was a metabolic difference between cattle and yaks. In general, the metabolic pathway of cattle was mainly riched in a de novo synthesis of nucleotides, whereas that of yaks was mainly riched in the metabolic utilization of nutrients. This study provides a basis for understanding a rumen ecology under the condition of a high concentrate diet.

This study compared growth performance, serum biochemical indicators, rumen fermentation parameters, rumen bacterial structure, and fecal bacterial structure of cattle and yaks, fed for two months, given a feed containing concentrate to roughage ratio of 7: 3 on dry matter basis. Compared with cattle, yak showed better growth performance. The serum biochemical results showed that the albumin: globulin ratio in yaks serum was significantly higher than that in cattle. Aspartate aminotransferase, indirect bilirubin, creatine kinase, lactate dehydrogenase and total cholesterol were significantly lower in yaks than that in cattle. Rumen pH, acetate to propionate ratio, and acetate were lower in yaks than in cattle while the lactate in yaks was higher than in cattle. There were significant differences in the structure of ruminal as well as fecal bacteria between cattle and yaks. The prediction of rumen bacterial function showed that there was metabolic difference between cattle and yaks. In general, the metabolic pathway of cattle was mainly riched in de novo synthesis of nucleotides, while that of yaks was mainly riched in the metabolic utilization of nutrients. This study provides a basis for understanding the rumen ecology under the condition of high concentrate diet.