Relationships of liver weight, cholesterol, albumin and alpha2-macroglobulin concentrations with ovarian function in swine

In two genetic swine models selected for diversity in ovulation rates (White composite controls and ovulation rate selection line, n = 131; 1/2 White composite: 1/2 Meishan crossbreds, n = 387), a positive relationship was established with liver weight and ovulation rate (P < 0.01). Serum changes of cholesterol, albumin and alpha2-macroglobulin were monitored during various stages of the luteal phase and follicular phase (days 17 and 19 of the estrous cycle; 1/2 White composite: 1/2 Meishan gilts). Serum cholesterol concentrations increased with liver weights (r = 0.19; P < 0.01) and corpora lutea numbers (r = 0.14; P < 0.01). Albumin concentrations were negatively correlated with corpora luteal numbers (r = -0.3; P < 0.01) but had no relationship with liver weight. Serum concentrations of alpha2-macroglobulin were not related to liver weight or corpora lutea numbers. Circulating concentrations of cholesterol and alpha2-macroglobulin increased with day of the estrous cycle (P < 0.01). Testosterone concentrations were inversely related to circulating cholesterol concentrations during the estrous cycle, but testosterone concentrations on day 17 or 19 of the cycle were unrelated to corpora lutea numbers. Concentrations of estrone on day 17 or 19 (as an index of follicles destined to ovulate) were also not related to numbers of corpora lutea. Many interactions between liver and ovarian function involving metabolic and endocrine systems are plausible, but defined mechanisms resulting in coordinate increases in liver weight and ovulation rates are presently unelucidated.