Vitamin A nutrition of growing cockatiel chicks (Nymphicus hollandicus).
The experiments examined the physiological response of growing cockatiel chicks to varying levels of dietary vitamin A (VA) or beta-carotene and the rate of liver VA uptake. Adult cockatiels breeding pairs (n=10 pairs) were fed a VA-deficient diet for approximately 90 days prior to onset of egg laying. Breeding pairs were then allowed to feed their chicks diets containing either 0 IU VA/kg, 4000 IU VA/kg, or 2.4 mg beta-carotene/kg. After 5 weeks, chicks fed 0 IU VA developed poor feathering, facial dermatitis and reduced body weight (p<0.05). Liver VA was higher in chicks fed 4,000 IU VA or 2.4 mg beta-carotene vs. those fed 0 IU VA (p<0.05). Duodenal beta-actin and 15,15'-dioxygenase mRNA expression was similar to that of growing chickens, and greatest for cockatiel chicks fed 0 IU VA (p<0.01). Chicks fed 0 IU VA had keratinization of the bursa and oral mucosa, and reduced bursa development and lymphocyte density (p<0.05). Finally, when chicks fed 0 IU VA were orally gavaged with 20 IU VA/g body weight, maximal liver retinol uptake occurred between 0 and 24 h and reached a plateau at 36 h. These data demonstrate that VA deficiency can be prevented with 4,000 IU VA/kg diet or 2.4 mg beta-carotene/kg diet, although beta-carotene conversion to VA may be lower in cockatiels than chickens.
Koutsos
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EA
Animal Science Department, California Polytechnic State University, San Luis Obispo, CA. ekoutsos@calpoly.edu
Klasing
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KC
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage; D046410:Cockatoos / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D005241:Feathers; D005260:Female; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010058:Oviposition; D014801:Vitamin A / Q000008:administration & dosage* / Q000378:metabolism; D019207:beta Carotene / Q000008:administration & dosage* / Q000378:metabolism
D000975:Antioxidants; D019207:beta Carotene; D014801:Vitamin A