At pasture outlet, mean plasma vitamin B12 varied between 210 and 1,200 pmol/l in 1 month old lambs, 19% of them had values below 250 pmol/l. In those put on OWLD pastures, mean values dropped after 2-4 weeks, and mostly stayed below 150 pmol/l throughout grazing. Plasma methylmalonic acid (MMA) rose above 5 mumol/l 2-8 weeks after outlet, and above 15 mumol/l 4 weeks later. Reduced growth occurred 3-8 weeks after plasma B12 dropped below 150 pmol/l, and 4-6 weeks after MMA rose above 5 mumol/l. Clinical OWLD was most often associated with plasma B12 less than 150 pmol/l and MMA greater than 15 mumol/l. Cobalt fertilization of pastures induced satisfactory plasma B12/MMA values for 3 succeeding years. Elevated plasma B12 was found 3 weeks after Co pellet dosing. The use of Co lick resulted in large individual variations in plasma B12/MMA. The control lambs, which were healthy and grew well on pastures which some years contained marginal/deficient cobalt, had plasma B12/MMA values which varied considerably. One year values indicated functional Co deficiency, but none developed OWLD, and growth was satisfactory, but less than other years. In these lambs, high MMA was not always associated with low B12, or depressed growth. OWLD occurred in Co/B12 deficient lambs, but Co/B12 deficient lambs on other pastures did not develop OWLD.
Ved beiteslipp hadde 19% av de månedsgamle lamma plasma vitamin B12 under 250 pmol/1. Hos alle lam som ble satt på OWLD-beitene sank verdiene etter 2–4 veker, og var som regel under 150 pmol/1 iløpet av beiteperioden. Plasma methylmalonsyre (MMA) steg over 5 μmol/1 2–8 veker etter slipp, og over 15 μmol/1 4 veker senere. Redusert tilvekst kom 3–8 veker etter at B12 var sunket under 150 pmol/1, og 4–6 veker etter at MMA steg til over 5 μmol/1. OWLD var som regel assosiert med plasma B12 uder 150 pmol/1 og MMA over 15 μmol/1.
Koboltgjødsling av beitet ga tilfredsstillende plasma B12/MMA hos lamma i 3 år etterpå. Ved dosering med koboltpellets var B12 forhøyet 3 veker senere. Bruk av kobolt saltslikkestein resulterte i store individuelle variasjoner i plasma B12/MMA.
Kontrollamma varierte sterkt mhp plasma B12/M-MA. I 1986 indikerte verdiene funksjonell koboltmangel, men ingen utviklet OWLD, og veksten var tilfredsstillende, men noe mindre enn andre år. Hos disse lamma var ikke alltid høyt MMA korrelert til lavt B12, eller til nedsatt vekst. OWLD forekom hos Co/B12 deficitte lam, men Co/B12 deficiette lam på andre beiter utviklet ikke OWLD.