Abstract
The goal of this study was to evaluate the effects of clove (Syzygium aromaticum) supplementation levels on performance, blood parameters, and immune response of broilers. A total of 336 one-day-old broilers were assigned to one of eight treatments: 1% to 6% clove supplementation levels, a positive control (vaccinated) and a negative control (unvaccinated). Bodyweight gain, feed intake, feed conversion ratio, serum protein profile, and immune responses were measured weekly. Lymphoid organs were weighed at 21 and 35 days. Levels of dietary clove between 2% and 6% supplementation resulted in a gradual decrease in weight gain and feed intake with an increase in feed conversion ratio at two and three weeks, whereas those that received 4% to 6% supplementation had reduced weight gain and the 3% to 6% supplemented animals consumed the least amount of feed at four and five weeks. High levels of clove supplementation (4%, 5%, and 6%) resulted in reduced total serum protein and albumin and the greatest activity of aspartate aminotransferase at 35 days. Antibodies to viruses against which the birds had been vaccinated were not affected by different levels of clove supplementation compared with the positive control. However, they were increased in birds in the negative control group without vaccination. Relative weights of lymphoid organs were not affected by any treatments at 21 and 35 days. These results indicate that clove supplementation at levels greater than 2% can lead to negative effects on performance without improving the health of the liver and immune responsiveness of broilers.