Comparison of effects of Isotricha monofauna and total mixed fauna on dietary copper metabolism in lambs

Abstract

Three groups of 15 fauna-free (FF) lambs each were used to establish the effects of Isotricha sp. (IS) monofauna on the dietary copper (Cu) solubility in the stomach and on the concentration of Cu in the liver. One group remained FF (control) while the second and third groups were inoculated with IS and total mixed fauna (TF), respectively. All lambs were fed ad libitum a corn silage based diet for 168 d. Thereafter, the lambs were killed and livers, kidneys and stomachs were removed and sampled. Different fauna treatments did not affect (P > 0.1) growth performance parameters. In comparison with the FF sheep, both the TF and IS decreased (P < 0.05) the rumen solubility of Cu, but the decrease by IS (23%) was approximately half of that of TF (41%; P < 0.05). Similarly, TF and IS decreased the liver Cu concentration by 15% (P < 0.1) and 7.5% (P > 0.1), respectively. Although TF that significantly decreased the bioavailability of dietary Cu included IS and Dasytricha species, it appears that an absence of these Holotrich protozoa from the rumen protozoa population would not have a significant effect on the efficiency of the population to alleviate chronic copper toxicity in sheep. Key words: Isotricha, rumen, ciliate protozoa, lambs, copper