Effects of long-term parenteral administration of vitamin B6 on B6 status and some aspects of the glucose and protein metabolism of early-weaned piglets.
The present experiment aimed to determine the effect of feeding level and parenteral supplements of vitamin B6 (pyridoxine) on B6 status as well as on glucose, C-peptide, insulin, alpha-amino-N and urea after a gastric bolus of glucose in weaned piglets; the plasma tryptophan, xanthurenic acid and kynurenine responses to a gastric bolus of tryptophan were also measured. Forty-two piglets weaned at 2 weeks of age were distributed in seven blocks of six animals each. Within each block, the animals were assigned to the following factorial treatments: two levels of feeding (28 (F28) and 56 (F56) g/kg(0.75) per d) administered by gastric-tube feeding and three levels of parenteral (intramuscular injections) vitamin B6 (0 (B60), 15 (B615) and 30 (B630) mg/d). In B60 piglets, a decrease of 30 % and 20 % in erythrocyte and plasma pyridoxal-5-phosphate respectively, were observed during the 2 weeks post-weaning. In supplemented piglets, the erythrocyte pyridoxal-5-phosphate was maximised in B615 piglets at a level 3-4 times higher than in B60 piglets (P < 0.003). However, in plasma the maximal pyridoxal-5-phosphate concentration was reached in F28-B630 piglets (P < 0.058). The glucose and insulin responses to a gastric bolus of glucose were lower, and the post-bolus decrease of glucose was slower, in F28 than in F56 piglets (P < 0.0001). The insulin:C-peptide ratio was 25 % greater in B615 piglets (P < 0.082). After the bolus of glucose, the aminoacidaemia decreased differentially according to treatments (P < 0.047), while the uraemia was at least 2-fold higher (P < 0.001) in F28 piglets than in F56 piglets and tended to be maximised in B630 piglets (P < 0.074). The response of plasma tryptophan to the gastric bolus of tryptophan was 11 % lower in B630 piglets (P < 0.057). The plasma concentration of kynurenine increased continuously during the post-bolus period and this response was more marked in F56 (P < 0.002) and in B630 piglets (P < 0.02). Xanthurenic acid was undetectable in any of the treatments. The measurements on pyridoxine status suggest that the present basal dietary level of B6 (7.7 mg/kg) was not sufficient to cover the metabolic needs. For many criteria, an optimal level was reached at 15 mg/d parenteral B6 but the response of urea to glucose bolus suggests that 30 mg/d was detrimental. Further studies are necessary to determine the dietary level of B6 equivalent to the present optimal parenteral supplements and its eventual effects on B6 status and post-weaning growth performance of piglets.
Matte
J J
JJ
Dairy and Swine R & D Center, Agriculture and Agri-Food Canada, P.O. Box 90, Lennoxville, Québec J1M 1Z3, Canada. mattej@em.agr.ca
Girard
C L
CL
Sève
B
B
D000375:Aging / Q000097:blood; D000596:Amino Acids / Q000097:blood*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D001823:Body Composition / Q000187:drug effects; D004032:Diet; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D007273:Injections, Intramuscular; D008297:Male; D011732:Pyridoxal Phosphate / Q000097:blood; D011736:Pyridoxine / Q000008:administration & dosage / Q000494:pharmacology*; D013552:Swine / Q000097:blood* / Q000502:physiology; D014364:Tryptophan / Q000097:blood; D014886:Weaning; D015430:Weight Gain / Q000187:drug effects
D000596:Amino Acids; D001786:Blood Glucose; D011732:Pyridoxal Phosphate; D014364:Tryptophan; D011736:Pyridoxine