Growth response in lambs injected with a long acting microencapsulated Vitamin B12

Extract Cobalt (Co) deficiency is an important problem in New Zealand grazing livestock, particularly in young lambs (Andrews, 1965 Andrews, ED. 1965. Observations on the thrift of young sheep on a marginally cobalt-deficient area. New Zealand Journal of Agricultural Research, 8: 788–817. [Taylor & Francis Online] , [Google Scholar]; Grace, 1994 Grace, ND. 1994. “Cobalt (Co)”. In Managing trace element deficiencies 25–34. Palmerston North: New Zealand Pastoral Agricultural Research Institute Limited,. [Google Scholar]). The deficiency is characterised by loss of appetite, poor growth rates and a watery eye discharge (Andrews et al., 1966 Andrews, ED, Stephenson, BJ, Isaacs, EC and Register, RH. 1966. The effects of large doses of soluble and insoluble forms of cobalt given at monthly intervals on cobalt deficiency disease in lambs. New Zealand Veterinary Journal, 14: 191–196. [Taylor & Francis Online] , [Google Scholar]). In order to synthesise sufficient amounts of vitamin B12 the microorganisms in the reticulorumen require an adequate intake of Co, which for sheep is provided by pastures containing 0.1 mg Co/kg DM. Vitamin B12 is a cofactor for two important enzymes, namely, methylmalonyl coenzyme A mutase and methionine synthase. About half of the glucose required by sheep is acquired by gluconeogensis from propionic acid (Judson et al., 1968 Judson, GJ, Anderson, E, Luick, JR and Leng, RA. 1968. The contribution of propionate to glucose synthesis in sheep given diets of (different grain content. British Journal of Nutrition, 22: 69–75. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) a volatile fatty acid produced in the reticulorumen during fermentation. The propionic acid is converted to succinc acid by the methylmalonyl coenzyme A mutase and the succinc acid is then metabolised to glucose via the tricarboxylic cycle and the glycolytic pathway (Rice et al., 1989 Rice, DA, McLoughnin, M, Blanchflower, WJ, McMurray, CH and Goodall, EA. 1989. Sequential changes in plasma methylmalonic acid Vitamin B12 in sheep eating cobalt-deficient grass. Biological Trace Element Research, 22(1): 153–64. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Methionine synthase converts homocysteine to methionine an essential amino acid (Kennedy et al., 1992 Kennedv, DG, Blanchflower, JW, Scott, JM, Weir, DG, Molly, AM, Kennedy, S and Young, PB. 1992. Cobalt-Vitamin B12 deficiency decreases methionine synethase activity and phospholipid methylation to sheep. Journal of Nutrition, 122: 1384–90. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Thus Co deficiency impairs the energy and protein metabolism of ruminants.