Liver lipid content and inflammometabolic indices in peripartal dairy cows are altered in response to prepartal energy intake and postpartal intramammary inflammatory challenge

摘要

This study evaluated the effect of feeding a control diet (CON) or a moderate energy diet (overfed, OVE) during the dry period (~45 d) and a postpartum intramammary lipopolysaccharide (LPS) challenge on blood metabolic and inflammatory indices, milk production, and hepatic gene expression. A subset of cows (n = 9/ diet) in CON (1.34 Mcal/kg of dry matter) and OVE (1.62 Mcal/kg of dry matter) received an intramammary LPS challenge (200 μg; CON-LPS, OVE-LPS, respectively). Liver biopsies were harvested at —14 d from calving, and postpartum at 2.5 h post-LPS on d 7, 14, and 30. Prepartum, the OVE group was in more positive energy balance (EB) and had greater body condition score compared with CON. In contrast, during wk 1 postpartum and before the LPS challenge, the OVE group was in greater negative EB than CON. Prepartal diet did not affect postpartal milk production or dry matter intake. At 2 h postchallenge on d 7, we observed an increase in serum nonesterified fatty acids (NEFA) and bilirubin and a decrease in hydroxybutyr-ate, regardless of diet. That was coupled with greater haptoglobin in OVE-LPS compared with CON-LPS. In addition, OVE-LPS cows versus CON nonchallenged, OVE nonchallenged, and CON-LPS had greater liver triacylglycerol (TAG) concentration 2.5 h postchallenge on d 7. The concentration of TAG in liver of OVE-LPS remained elevated by 30 d postpartum. The liver TAG concentration in OVE-LPS compared with CON-LPS cows was associated with greater serum concentration of NEFA and reactive oxygen metabolites on d 10 and 14 postpartum. Cows in OVE-LPS also had greater concentrations of ceruloplasmin, cholesterol, and vitamin E from d 10 through 21. Among 28 genes associated with fatty acid oxidation, inflammation, oxidative stress, and gluconeogenesis, only SAA3 (which encodes an acute phase protein) was greater in CON-LPS compared with OVE-LPS at 2.5 h postchallenge. Expression of HP, which encodes another acute phase protein, was greater in OVE-LPS than in CON-LPS at 14 and 30 d postpartum. Several inflammation-related genes (TNF, IRAKI, NFKB1, ANGPTL4) showed markedly decreased expression between 7 and 14 d, after which expression remained unchanged. No differences were observed in several genes of the growth-hormone/ insulin-like growth factor-1 axis, except for SOCS2, expression of which decreased markedly between 7 and 14 d in OVE-LPS but not in CON-LPS. These data suggest that overfeeding a moderate-energy diet prepartum alters the response of the cow to an intramammary challenge after calving and may predispose it to sustained liver lipidosis.