408. Liver gene expression in suckled postpartum beef cows maintained on moderate and improved subtropical pasture
F. Samadi A , H. M. Nadzir A , N. J. Phillips B , M. M. McGowan B , SA Lehnert C , J. J. Loor D , M. Bionaz D and M. J. D.’Occhio AA School of Animal Studies, The University of Queensland, Gatton, Qld, Australia.
B School of Veterinary Science, The University of Queensland, Brisbane, Qld, Australia.
C Livestock Industries, CSIRO, Brisbane, Qld, Australia.
D Department of Animal Sciences, University of Illinois, Urbana, Illinois, United States.
E CRC for Beef Genetic Technologies, Armidale, NSW, Australia.
Reproduction, Fertility and Development 20(9) 88-88 https://doi.org/10.1071/SRB08Abs408
Published: 28 August 2008
Abstract
The liver is the first organ to receive absorbed nutrients from the splanchnic vasculature1 which places the liver at an important juncture between nutrition, metabolic homeostasis and reproductive function. The best described component of this interface is secretion of IGF-1 by the liver and dependence of ovarian follicular maturation on hepatic-derived IGF-12. The aim in the present study was to ascertain the expression of hepatic genes associated with metabolic regulation in postpartum beef cows maintained on moderate or improved pasture, and with contrasting liveweight and body condition. Multiparous Droughtmaster cows (Bos taurus × Bos indicus) were placed on moderate (MP, n = 7) or improved (IP, n = 7) pasture at 6–7 months of gestation and remained on the treatments after calving. Liver biopsies were taken 6 weeks after calving and gene expression was determined by quantitative PCR using SYBR Green3. Week 6 represents attainment of the plateau in nutrient demand for lactation. Data were analysed by ANOVA using SAS STAT. One week after calving, IP cows had greater (P < 0.01) liveweight and body condition score (BCS) than MP cows (585 ± 12 kg and 528 ± 21 kg; 3.7 ± 0.2 BCS and 2.3 ± 0.2 BCS). IP cows had greater (P < 0.05) relative expression of hepatic genes associated with cholesterol biosynthesis (sterol regulatory element binding factor, SREBF2; peroxisome proliferators-activated receptor delta, PPARD), fatty acid biosynthesis (carnitine palmitoyl-transferase, CPT1A; acyl-CoA oxidase, ACOX1; fatty acid desaturase 1, FADS1; sterol regulatory element binding factor 1, SREBF1) and insulin signalling (hepatic insulin receptor substrate 1, IRS1). IP cows resumed cyclic ovarian function between 11–16 weeks postpartum and one MP cow had cycled by 16 weeks. The differences in expression of metabolic genes between MP and IP cows may have partly contributed to differences in reproductive function postpartum.
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(2) Lucy MC 2000 Journal of Dairy Science 83:1635–47
(3) Loor JJ et al. 2006 Physiological Genomics 27:29–41
