Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2006
Publication Date: 5/1/2007
Citation: Farmer, H., Petit, H.V., Weiler, H., Capuco, A.V. 2007. Effects of dietary supplementation with flax during prepuberty on fatty acid profile, mammogenesis and bone metabolism in gilts. Journal of Animal Science. 85(7):1675-1686. Interpretive Summary: Flaxseed contains estrogenic compounds and fatty acids that may influence early growth of the mammary gland and bone resorption. The possible role of dietary flax on these processes was studied in gilts. Effects of diets that were supplemented with flaxseed, flaxseed oil, or flaxseed meal were evaluated and compared to effects of a control diet. Effects of dietary fatty acids should have been most noted with diets supplemented with flaxseed or flaxseed oil and effects of phytoestrogens with flaxseed or flaxseed meal. Results indicate that dietary flaxseed or flaxseed oil increased the concentrations of polyunsaturated fatty acids in plasma and extraparenchymal mammary tissue. No changes in growth of the mammary gland or in the potential responsiveness of mammary gland to estrogen (estrogen receptor content) were evident. Plasma concentrations of telopeptide of type I collagen, which is a highly bone-specific parameter and serves as an indicator of bone resorption were not altered. Thus, dietary supplementation with flax brought about expected changes in fatty acid profile, but had no beneficial effects on either mammary development or bone resorption.
Technical Abstract: The possible role of dietary flax on prepubertal development of mammary glands and bone resorption was investigated in gilts. Fifty-seven gilts were fed one of four diets from 88 d of age until slaughter (day 212 ± 1). Diets were: control without flax, CTL (n = 14); 10% flaxseed supplementation, FS (n = 13); 6.5% flaxseed meal supplementation, FSM (n = 15); and 3.5% flaxseed oil supplementation, FSO (n = 15). All diets were isonitrogenous, isolipidic and isocaloric. Jugular blood samples were obtained on days 78 and 210 to establish fatty acid profile and determine concentrations of prolactin, estradiol and telopeptide of type I collagen (NTx). 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 and fatty acid profiles in extraparenchymal tissue were evaluated. Dietary flax increased )P<0.001) the concentrations of polyunsaturated fatty acids (PUFA) and decreased those of saturated (SFA, P < 0.01) and monounsaturated (MUFA, P < 0.001) fatty acids in both plasma and extraparenchymal tissues. This was largely due to the inclusion of FS or FSO (P < 0.01), but not FSM. Circulating concentrations of prolactin and estradiol were unaltered by treatments (P > 0.1) and NTx concentrations tended to be greater (P < 0.1) in flax-supplemented gilts. Dry matter content of parenchymal tissue was the only mammary compositional value affected, showing an increase with flax addition (P < 0.05). No changes (P > 0.1) in BrdU labelling index or estrogen receptor localization were observed with treatments. Dietary supplementation with flax as seed, meal or oil, therefore brought about expected changes in fatty acid profile but had no beneficial effects on either mammary development or bone resorption.