Changes in serum concentrations of folates, pyridoxal, pyridoxal-5-phosphate and vitamin B₁₂ during lactation of dairy cows fed dietary supplements of folic acid

Abstract

Girard, C. L. and Matte, J. J. 1999. Changes in serum concentrations of folates, pyridoxal, pyridoxal-5-phosphate and vitamin B 12 during lactation of dairy cows fed dietary supplements of folic acid. Can. J. Anim. Sci. 79: 107-113. The present experiment was undertaken to determine the effects of dietary supplements of folic acid (FA) administered from 4 wk prepartum to 305 d of lactation on serum concentrations of folates, vitamin B 12 , pyridoxal-5-phosphate (P-5-P) and pyridoxal. In addition, concentrations of blood hemoglobin and packed cell volume (PCV) were determined. Sixty-three Holstein cows were assigned to 22 incomplete blocks according to lactation number, milk production and body weight (BW). Within each block, cows received 0, 2 and 4 mg FA d -1 kg -1 BW. Dietary supplements of FA increased serum concentrations of folates (time × FA, P = 0.0001); the highest concentrations were observed during the first two months of lactation in cows fed supplementary FA. The lowest serum concentrations of vitamin B 12 were also observed during the first two months of lactation, and the concentrations were lower in primiparous than in multiparous cows (time × parity, P = 0.03). Serum concentrations of P-5-P and pyridoxal were not affected by the dietary supplements of FA (P > 0.1). In multiparous cows, dietary supplements of FA had no effect on changes of hemoglobin and PCV during the lactation (time × FA, P > 0.13). In primiparous cows, PCV and hemoglobin were lower in control cows at parturition whereas by 24 wk of lactation, they were higher in cows fed the highest amount of FA. The lowest values of hemoglobin and PCV were observed during the first two months of lactation. These results give an indication that supply of B-complex vitamins by ruminal microorganisms could be suboptimal for high-producing dairy cows, for example, in early lactation when fed a diet with a high proportion of concentrates. More research is needed to determine the metabolic consequences of these variations. Les supplé-ments alimentaires d'acide folique ont augmenté les concentrations sériques de folates (temps × AF, P = 0.0001); les concentrations les plus élevées ont été observées pendant les deux premiers mois de lactation chez les vaches recevant les suppléments d'acide folique. Les plus faibles concentrations sériques de vitamine B 12 ont aussi été observées pendant les deux premiers mois de lactation et ces concentrations étaient plus faibles chez les primipares que chez les multipares (temps × parité, P = 0.03). Les concentrations sériques de P-5-P et de pyridoxal n'ont pas été modifiées par les suppléments d'acide folique (P > 0.1). Chez les multipares, les suppléments alimentaires d'acide folique n'ont pas modifié les concentrations d'hémoglobine sanguine et l'héma-tocrite pendant la lactation (temps × AF, P > 0.13). Chez les primipares, l'hématocrite et la concentration d'hémoglobine étaient plus faible à la parturition chez les témoins alors qu'à 24 semaines de lactation, les valeurs les plus élevées ont été observées chez ...

Effects of the forage to concentrate ratio on B-vitamin concentrations in different ruminal fractions of dairy cows

“…Similarly, Girard and Matte (1999) observed that serum concentrations of true vitamin B 12 were higher in multiparous than in primiparous cows, although absolute values were higher than in the present experiment. Our results suggest that in multiparous cows, diet composition had a limited effect on plasma concentrations of analogues and the proportion of vitamin B 12 as true vitamin B 12 .…”

“…On the other hand, Girard and Matte (1999) observed no effect of parity on serum folate concentrations in their experiment using cows from 1 mo before expected calving until the end of the subsequent 305-d lactation. These differences between parities are most likely due to a different metabolism between primiparous and multiparous cows.…”

Comparative mammalian choline metabolism with emphasis on the high-yielding dairy cow

“…* The de novo synthesis of methyl groups via the THF system appears to be minimal in ruminants when labile methyl intake is sufficient or excessive, for example in the preruminant lamb (Xue & Snoswell, 1986a;Snoswell & Xue, 1987). † Methionine, folic acid and vitamin B 12 , which all contribute to meeting the requirement for choline, are often limiting nutrients in high-yielding dairy cows (McDowell, 1989;Girard, 1998;Girard & Matte, 1999;Petitclerc et al 2000). ‡ It is also important to note that the precursors of gluconeogenesis, the primary sources of one-carbon units for methylneogenesis via the THF system, are often deficient in lactating ruminants (Armentano, 1994;Rukkwamsuk et al 1999).…”

Impact of B-vitamin supply on major metabolic pathways of lactating dairy cows

“…Girard and Matte (1999) observed low levels of serum vitamin B 12 in early lactation, more so in primiparous than in multiparous cows. In contrast, in that same experiment, folic acid supplementation increased the milk and milk protein yields of multiparous cows but not primiparous cows (Girard and Matte 1998).…”