Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 27, 2000
Publication Date: N/A
Interpretive Summary: Coccidiosis is a protozoan disease that costs the U.S. poultry industry in excess of $600 million annually. Control of coccidiosis is primarily through the use of anticoccidial drugs, however, new methods are becoming of increased interest. One method is the use of feed additives such as betaine. Earlier, betaine, in combination with salinomycin, was shown to significantly improve growth performance, reduce intestinal pathology, and increase absorption of methionine in coccidia-infected broiler chicks. The present work demonstrated that these effects were associated with marked increases in the betaine levels of intestinal and kidney tissues in uninfected and coccidia-infected chicks. Moreover, the increases in betaine levels as well the effects on growth performance were highly dependent upon the coccidial species. Betaine has a number of important physiological activities such as osmoprotection, water retention, and enhancement of digestability of nutrients, and these all may have contributed to the protection against the negative impact of coccidiosis.
Weight gain and intestinal, kidney, and plasma levels of betaine in broiler chicks fed a nutritionally-adequate diet supplemented with 0.15% betaine were compared with those of chicks fed the unsupplemented diet. The chicks were uninfected or were infected with Eimeria acervulina, E. maxima, or E. tenella. Weight gains of uninfected chicks were enhanced slightly by dietary betaine in two experiments and significantly in a third. Weight gains of E. maxima-infected chicks were significantly improved by betaine supplementation whereas gains were not altered in chicks infected with E. acervulina or E. tenella. Betaine levels in the duodenum of uninfected, betaine-supplemented chicks (55.6 umol/g) were significantly higher than those in uninfected chicks fed the control diet (5.5 umol/g). In the midgut, betaine levels in uninfected chicks fed the betaine diet were significantly higher than those of uninfected controls (23.5 and 7.5 umol/g gtissue, respectively). There was little effect of betaine-supplemented feed on cecal levels of betaine. Kidney levels in uninfected chicks fed the betaine diet were ~ twice that in the controls (13.7 and 7.4 umol/g, respectively), although the differences were not significant. In infected chicks, the effects of betaine supplementation varied with the species of Eimeria. In chicks infected with E. acervulina or E. maxima, betaine levels in duodenal and midgut tissues of betaine-supplemented chicks were markedly higher than those of unsupplemented chicks, although they were less than half of the levels in uninfected chicks. There was little difference in betaine levels in cecal tissues between the two diet groups. Kidney and plasma betaine levels in infected chicks were increased by betaine supplementation of the feed, especially with E. acervulina and E.