Effects of concentrations of cyanocobalamin in the gestation diet on some criteria of vitamin B₁₂ metabolism in first-parity sows

¹ Département des Sciences Animales, Université Laval, Québec, QC, Canada; Maple Leaf Animal Nutrition, Lévis, QC, Canada
² Département des Sciences Animales, Université Laval, Québec, QC, Canada
³ Agriculture and Agri-Food Canada, Dairy and Swine R & D Centre, Sherbrooke, QC, Canada

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

	Abstract

In swine nutrition, little is known about the role of vitamin B₁₂ in the reproductive processes. The present study was undertaken to obtain information on the dose-response pattern of different metabolic criteria related to homeostasis of vitamin B₁₂ and homocysteine in gestating sows receiving various concentrations of dietary vitamin B₁₂ (cyanocobalamin). Homocysteine is a detrimental intermediate metabolite of the vitamin B₁₂-dependent remethylation pathway of methionine. Forty nulliparous (Large White x Landrace) sows were randomly assigned during gestation to dietary treatments containing 5 concentrations of cyanocobalamin (0, 20, 100, 200, and 400 µg·kg^-1). During lactation, a diet containing 25 µg of cyanocobalamin per kg was fed to all sows. During gestation, plasma vitamin B₁₂ increased as concentrations of dietary cyanocobalamin (linear and quadratic, P < 0.01) and the effect persisted during lactation (21 d) both in plasma (linear and quadratic, P < 0.05) and liver (linear and quadratic, P < 0.04). Plasma homocysteine decreased with concentrations of cyanocobalamin provided to sows during gestation (linear, quadratic and cubic, P < 0.01). At parturition, colostral vitamin B₁₂ in colostrum increased with concentrations of cyanocobalamin (linear and quadratic, P < 0.01), but the treatment effect persisted (linear, P = 0.01) only up to 1 d post-farrowing. However, in piglets there was no treatment effect (P = 0.59) on plasma vitamin B₁₂ before colostrum intake, a linear effect of concentrations of cyanocobalamin (P = 0.04) was observed 1 d later. Plasma homocysteine in piglets during lactation decreased with increasing cyanocobalamin given to sows in gestation (linear and quadratic, P < 0.01). Based on a broken-line regression model, the concentrations of cyanocobalamin that maximized plasma vitamin B₁₂ and minimized plasma homocysteine of sows during gestation were estimated at 164 and 93 µg·kg^-1, respectively. The maximal residual responses in sows and piglets during lactation were observed with treatments 100 or 200 µg of cyanocobalamin per kg. The dietary cyanocobalamin concentration necessary to optimize the response of these metabolic criteria remains to be refined within lower and narrower ranges of cyanocobalamin concentrations (< 200 mg·kg^-1). Moreover, the biological significance of such concentrations of cyanocobalamin needs to be validated with performance criteria using greater numbers of animals during several parities.

Key Words: gestation, gilts, homocysteine, milk, piglets, vitamin B₁₂