title: Effects of Starvation on Lipid Metabolism and Gluconeogenesis in Yak.
abstract: This research was conducted to investigate the physiological consequences of undernourished yak. Twelve Maiwa yak (110.3±5.85 kg) were randomly divided into two groups (baseline and starvation group). The yak of baseline group were slaughtered at day 0, while the other group of yak were kept in shed without feed but allowed free access to water, salt and free movement for 9 days. Blood samples of the starvation group were collected on day 0, 1, 2, 3, 5, 7, 9 and the starved yak were slaughtered after the final blood sample collection. The liver and muscle glycogen of the starvation group decreased (p<0.01), and the lipid content also decreased while the content of moisture and ash increased (p<0.05) both inLongissimus dorsiand liver compared with the baseline group. The plasma insulin and glucose of the starved yak decreased at first and then kept stable but at a relatively lower level during the following days (p<0.01). On the contrary, the non-esterified fatty acids was increased (p<0.01). Beyond our expectation, the ketone bodies of β-hydroxybutyric acid and acetoacetic acid decreased with prolonged starvation (p<0.01). Furthermore, the mRNA expression of lipogenetic enzyme fatty acid synthase and lipoprotein lipase in subcutaneous adipose tissue of starved yak were down-regulated (p<0.01), whereas the mRNA expression of lipolytic enzyme carnitine palmitoyltransferase-1 and hormone sensitive lipase were up-regulated (p<0.01) after 9 days of starvation. The phosphoenolpyruvate carboxykinase and pyruvate carboxylase, responsible for hepatic gluconeogenesis were up-regulated (p<0.01). It was concluded that yak derive energy by gluconeogenesis promotion and fat storage mobilization during starvation but without ketone body accumulation in the plasma.
authors.affiliation: Animal Nutrition Institute, Key Laboratory of Low Carbon Culture and Safety Production in Cattle in Sichuan, Sichuan Agricultural University, Ya'an, Sichuan 625014, China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Yu
authors.affiliation: Animal Nutrition Institute, Key Laboratory of Low Carbon Culture and Safety Production in Cattle in Sichuan, Sichuan Agricultural University, Ya'an, Sichuan 625014, China.
authors.forename: Quanhui
authors.initials: Q
authors.lastname: Peng
authors.affiliation: Grassland Science Academy of Sichuan Province, Chengdu, Sichuan 611731, China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Luo
authors.affiliation: Grassland Science Academy of Sichuan Province, Chengdu, Sichuan 611731, China.
authors.forename: Tianwu
authors.initials: T
authors.lastname: An
authors.affiliation: Grassland Science Academy of Sichuan Province, Chengdu, Sichuan 611731, China.
authors.forename: Jiuqiang
authors.initials: J
authors.lastname: Guan
authors.affiliation: Animal Nutrition Institute, Key Laboratory of Low Carbon Culture and Safety Production in Cattle in Sichuan, Sichuan Agricultural University, Ya'an, Sichuan 625014, China.
authors.forename: Zhisheng
authors.initials: Z
authors.lastname: Wang
keywords: Fat Catabolism; Gluconeogenesis; Ketone Bodies; Maiwa Yak; Starvation