Effect of silymarin (Silybum marianum) treatment on prolactin concentrations in cyclic sows

An extract (silymarin) from the plant Silybum marianum (milk thistle) was shown to increase circulating concentrations of prolactin in cycling rats. A dose-response study was undertaken to determine if silymarin does have hyperprolactinemic properties in cycling swine. Forty-four weaned sows were allotted to four groups receiving 0, 1, 2 or 4 g d(-1) of silymarin over a period of 8 d. Blood samples were obtained on days 1 (first day of treatment starting 24 to 48 h after the onset of the standing estrus), 2, 3, and 9. Prolactin, progesterone, estradio1-17 beta and leptin concentrations were determined. Silymarin did not increase prolactin concentrations at any of the doses studied, nor did it affect concentrations of the other hormones (P >0.1).