الملخص الإنجليزي
Cobalt is an essential component of vitamin B12. In ruminants, vitamin B12 is synthesized by the microflora of the rumen. A dietary deficiency of cobalt in humans leads to clinical symptoms characterized by anaemia, and CNS manifestation, while in sheep it causes anorexia, anaemia, immunodeficiency and elevation of serum aspartate aminotransferase (AST) and gamma glutamyltransferase (GGT) levels. Goats are generally considered resistant to cobalt deficiency and because of this even the minimum daily cobalt requirements have not been established, nor are there established reference values for the normal levels of vitamin B12 in serum. A recent study from the Sultan Qaboos University, however, demonstrated that cobalt deficiency is associated with a condition, known as hepatic lipidosis in Omani goats. This condition is analogous to Ovine White Liver Disease (OWLD). The symptoms of OWLD in sheep are severe ill-thrift, anorexia, delayed growth, weight loss, cachexia, photosensitivity, anaemia, CNS manifestation and elevation of serum GGT and AST values. Anecdotal evidence at the field level suggests, however, that vitamin B12 deficiency in Omani goats might have other clinical manifestations. This is based on the observation that goats that were parasite free and suffering from ill thrift, responded positively to the introduction of intraruminal cobalt pellets or to systemic injection of vitamin B12. Therefore, the goal of this project is to determine the normal range of serum vitamin B12 in Omani goats, characterize the clinical signs, epidemiology, the serum biochemical and blood cell parameter status in relation to varying levels of serum vitamin B12. In this study, 200 Omani goats of both sexes and various age groups (1month to 11 years) within five different regions in Oman (Batinah, Muscat, Sharqiya, Dhahira and Dakhiliya) were studied. Survey questionnaires and physical examinations were under taken on each goat. Blood samples were collected for serum vitamin B12, serum chemistry, blood cell parameters and faecal samples for analysis. The serum vitamin B12 values in Omani goats ranged from 105->2000 pg/ml, with a mean value of 723.1+392 pg/ml. The mean + 2 standard error mean (SEM) was 667-779 pg/ml. Kids in the age groups 1-3 months showed significantly lower levels of serum vitamin B12 than the older animals. Goats maintained on commercial feed showed higher levels of serum vitamin B12 than those maintained on pasture or fed on left over feed. Varying levels of serum vitamin B12 were found in different regions of Oman. The highest levels were found in Sharqiya followed by Muscat, Batinah, Dhahira and Dakhiliya respectively and on farms of the same region. Goats with serum vitamin B12 levels of < 667 pg/ml were thin and emaciated and exhibited higher numbers of eosinophils and had higher coccidial counts than goats with vitamin B12 levels >779 pg/ml. The results of this study indicate that there is a wide range of serum vitamin B12 levels in Omani goats. Vitamin B12 levels appear to vary between different regions of the country and are significantly lower in younger animals. This may be due to the poorly developed rumen in young goats in which the microflora are less likely established to produce adequate amounts of vitamin B12. It also may be due to the degradation of vitamin B12 initially obtained solely through the colostrum of the newborn animals or perhaps is due to the greater metabolic requirements of young growing animals. The higher level of coccidial counts found in animals with lower levels of serum vitamin B12 suggests a possible decrease in resistance to certain parasitic infections. Finally, in this study the significant numbers of goats with low levels of serum vitamin B12 strongly suggest a great economic impact of inadequate levels of vitamin B12 on the health and welfare of goats in Oman,
