Tolerance of weanling pigs for dietary vitamin A and D.
Weanling cross-bred pigs (36 or 48) were caged individually and fed diets containing a supplement of vitamin A (Expt 1) or vitamin D3 (Expt 2) at levels representing 1, 5, 10, 25, 50 and 100 times the NRC (1988) estimated requirements, for 4 weeks. Growth rate, feed intake and feed/gain ratio were not influenced significantly. In Expt 1 the plasma retinol concentrations were at 4 weeks, respectively, 31.7, 39.4, 43.2, 42.9, 44.4, and 46.3 micrograms/dl (P less than 0.05). In Expt 2, the plasma 25(OH)D3 concentrations were at 2 weeks, respectively, 22.5, 29.5, 35.7, 46.2, 79.9, 135.3 ng/ml (P less than 0.001). Histological examination of lung, stomach, kidney, liver and heart indicated no abnormalities, but focal microscopic lesions consistent with osteochondrosis were found in pigs receiving vitamin A at levels over 10 times the requirement. The incidence of osteochondrosis at 2 weeks was, respectively, 0/8, 0/8, 0/8, 0/8, 0/8, and 1/8, and at 4 weeks was, respectively, 0/8, 0/8, 0/8, 2/8, 2/8 and 2/8. The NRC (1988) estimate of the requirement for vitamin D may be somewhat low since the concentration of plasma 25(OH)D was lower with 200 or 1,000 IU vitamin D/kg diet than at the start.
Blair
R
R
Department of Animal Science, University of British Columbia, Vancouver, Canada.
Burton
B A
BA
Doige
C E
CE
Halstead
A C
AC
Newsome
F E
FE
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet; D009928:Organ Specificity; D010007:Osteochondritis / Q000139:chemically induced / Q000378:metabolism / Q000662:veterinary*; D013552:Swine / Q000254:growth & development; D013553:Swine Diseases / Q000139:chemically induced* / Q000378:metabolism*; D014801:Vitamin A / Q000097:blood / Q000633:toxicity*; D014807:Vitamin D / Q000097:blood / Q000633:toxicity*; D014886:Weaning
D014801:Vitamin A; D014807:Vitamin D