Submitted to: Animal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/15/2009
Publication Date: 3/1/2010
Publication URL: hdl.handle.net/10113/41627
Citation: Farmer, C., Palin, M.F., Gilani, G.S., Weiler, H., Vignola, M., Choudhary, R.K., Capuco, A.V. 2010. Dietary genistein stimulates mammary development in gilts. Animal. 4(3):454-465. Interpretive Summary: Phytoestrogens are plant compounds that have estrogenic properties in animals. Phytoestrogens are normal components of soy-based animal diets and a particularly active phytoestrogen found in soy is genistein. The possible role of genistein on prepubertal development of mammary glands, hormonal status and bone resorption was investigated in gilts. Gilts were fed a control diet containing soya, a control diet without soya or the control diet supplemented with 2 g of genistein daily from 90 d to 183 d of age. Findings indicate that feeding phytoestrogens to gilts during the critical growth phase enhanced mammary development at puberty. Further work is needed to determine the optimal conditions of such a treatment (i.e., ideal dose, timing and duration), the potential effects on future lactation performance, as well as the mechanisms of action. Feeding genistein to growing gilts, however, had no impact on bone resorption.
Technical Abstract: The possible role of the phytoestrogen, genistein, on prepubertal development of mammary glands, hormonal status and bone resorption was investigated in gilts. Forty-five gilts were fed a control diet containing soya (CTLS, n = 15), a control diet without soya (CTL0, n = 15) or the CTLS diet supplemented with 2 g of genistein daily (GEN, n = 15) from 90 d of age until slaughter (d 183 ± 1). Both basal diets were isonitrogenous and isocaloric. Jugular blood samples were obtained on d 89 and 176 to determine concentrations of prolactin, estradiol, progesterone, IGF-I, phytoestrogens and N-telopeptide of type I collagen (NTx) (on d 176 only). At slaughter, mammary glands were excised, parenchymal and extraparenchymal tissues were dissected, and composition of parenchymal tissue (protein, fat, dry matter, DNA) was determined. Histochemical analyses of mammary parenchyma were performed. Dietary genistein increased parenchymal protein (P < 0.05) while decreasing dry matter (P < 0.05) and tending to lower fat content compared to the CTLS, but not the CTL0, diet. There was more parenchymal DNA (1.26 vs. 0.92 mg/g, P < 0.05) in GEN than CTLS gilts. Circulating concentrations of hormones or NTx (indicator of bone collagen resorption) were not affected by GEN (P > 0.1). Percent ERalpha-positive epithelial cells was lower (P < 0.05) in GEN than CTLS gilts whereas BrdU labelling index was unaltered (P> 0.1). Transcript levels for ERalpha, ERbeta, IGF1, EGF, EGFR and TGFA were not altered by treatments. Exposure to the phytoestrogen genistein during the growing phase in gilts therefore led to hyperplasia of mammary parenchymal tissue after puberty; yet, this was not accompanied by changes in mammary expression of selected genes or circulating hormone levels.