Vitamin C status in Sudanese camels

Abstract

Vitamin C (ascorbic acid), which is a potent antioxidant, recently has received a great deal of attention because of its positive action on the immune response and disease resistance of animals. Brief reviews are presented on ascorbic acid metabolism in animals and its relation with stressful conditions. The original research in this thesis is concerned mainly with the identification of various factors that are related with vitamin C status in Sudanese camels (Camelus dromedarius) kept under natural grazing conditions. The study was conducted in the Butana area, Central Sudan. As indicators of vitamin C status, the concentrations of ascorbic acid in blood, leukocytes, organs and milk were used. Irrespective of the season, the highest tissue ascorbic acid levels were observed in adrenals and liver, and the lowest levels were in heart. There were breed variations in vitamin C status, Arabi camels having the highest plasma ascorbic acid concentrations and Bishari’s the lowest, the Anafi’s showing intermediate values. In the Sudanese camels, gender did not affect plasma ascorbic acid concentrations. However, female camels excreted more ascorbic acid with urine than did males. The breeding season was associated with a reduction of vitamin C status in both males and females. Estrus versus non-estrus was associated with high plasma and leukocyte ascorbic acid concentrations. Lactating Arabi camels had higher plasma and leukocyte ascorbic acid levels than did their pregnant counterparts. The stage of lactation was associated with plasma vitamin C levels, the levels being higher when the animals were more than 180 days in lacatation. The ascorbic acid levels in milk parallelled those in plasma. Multiparous camels had higher ascorbic acid concentrations in their milk than did primiparous animals. New-born calves had higher plasma ascorbic acid concentrations than their dams. In the calves, plasma ascorbic acid declined as from birth and had stabilized after four weeks. In the dams, plasma ascorbic acid rose from parturition and reached a steady value after four weeks. Colostrum contained more ascorbic acid than milk. The simulated habitual diet of Sudanese camels, when compared with alfalfa as sole source of nutrition, lowered plasma and leukocyte levels of ascorbic acid. Infections due to sarcoptic mange, helminthiasis and trypanosomiasis were associated with a lowering of vitamin C status, the latter infection having the greatest impact. Brucellosis was associated with a reduction of ascorbic acid status and was so mastitis. It is assumed that ascorbic acid status is a reflection of disease resistance. The data may also indicate that infectious diseases may further lower disease resistance and that female camels in non-estrus versus those in estrus, pregnant versus lactating, non-pregnant camels, breeding versus non-breeding animals and Bishari versus Arabi and Anafi camels might be more sensitive to disease. Dietary supplements should be identified that enhance vitamin C status in Sudanese camels as their habitual, free-range diet tends to lower the status.