Effects of dietary supplementation with flax during prepuberty on fatty acid profile, mammogenesis, and bone resorption in gilts

¹ Agriculture and Agri-Food Canada, Dairy and Swine R & D Centre, P.O. Box 90, Lennoxville, QC J1M 1Z3, Canada
² School of Dietetics and Human Nutrition, McGill University, Ste-Anne-de-Bellevue, QC H9X 3V9, Canada
³ USDA-ARS, Bovine Functional Genomics Lab, Beltsville, MD 20705, USA

^* To whom correspondence should be addressed. E-mail: farmerc{at}agr.gc.ca.

	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 1 of 4 diets from 88 d of age until slaughter (d 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 and isocaloric. Jugular blood samples were obtained on d 78 and 210 to establish fatty acid profile and determine concentrations of prolactin, estradiol and telopeptide of type I collagen. 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 and decreased those of saturated (SFA, P < 0.01) and monounsaturated (P 0.001) fatty acids in both plasma and extraparenchymal tissues, which 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 change (P 0.1) in bromodeoxyuridine labelling index or estrogen receptor localization was 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.

Key Words: Bone resorption, flaxseed, mammary development, mammary glands, pigs, prepubertal females