Palatability of tannin-rich sericea lespedeza fed to broilers.

摘要

As parasites become resistant to available anthelmintics, new methods of control are needed. New drugs take a long time to develop in addition to being expensive; therefore, there is increasing interest in finding and using natural alternatives. Additionally, natural remedies are needed for the organic sector because synthetic drugs are not allowed and birds with outdoor access are likely to encounter parasites. Sericea lespedeza [SL; Lespedeza cuneata (Dum. Cours.) G. Don.] is a common perennial legume found in pastures across the southern United States that has been shown to be effective at controlling parasitic nematodes in small ruminants because of its condensed tannin content. Diets high in condensed tannins are often unpalatable to poultry; however, growers report that chickens maintained on pastures will consume SL. These reports and the level of consumption have not been verified. Therefore, before determining its potential in controlling parasites in poultry, we confirmed in a preliminary study that birds on pasture consumed SL (92% of birds examined had SL in crops), and in a subsequent study, dried SL leaves were added to a commercial broiler feed to determine the palatability of SL at various concentrations. Diets included 0 (control), 5, 10, or 20% SL (DM weight) and were fed from hatch until slaughter at 6 wk of age. Male broilers (n=80) were randomly divided into 8 groups and fed 1 of the 4 diets in replicate. Body weight gains were similar between the control and SL at 5%. Including more than 5% SL in the diet reduced individual BW (P<0.05). At the end of the feeding period, the digestive organs as a percentage of body weight of birds fed 20% SL were larger than those of control birds. Feed conversion was higher in the 20% SL treatment (2.31) than in the control treatment (1.63; P<0.05). Palatability of SL did not appear to be a problem because all treatment groups consumed a similar amount of feed. Therefore, the effects of SL on parasite control will be evaluated in subsequent studies.