Title : Combination Of Some Plant Bioactives To Replace Antibiotic Growth Promoters In Broiler Feed
Many attempts have been done to maintain good performance of poultry in response to the ban on the use of antibiotic growth promoters (AGP). A previous in vitro study reported that three sources of plant bioactives ie., liquid smoke of cashew nuts (Anacardium occidetale) shells, clove (Syzygium aromaticum) leaves and leafflower (Phylanthus niruri) extracts have good activities for inhibiting growth of pathogenic bacteria, fungi and high antioxidant levels, respectively (Sinurat et al., 2018). This study was designed based on the previous results to evaluate the effectivity of the combination of those bioactives as feed additives to replace AGP in diet of broiler chickens. Three (3) levels of bioactives in liquid form and 3 levels in powder form were supplemented into a standard broiler diet without AGP (or negative control diet) and one diet supplemented with AGP (or positive control diet) was included in the trial. Each diet was fed to 70 broilers (7 replicates of 10 birds/pen) from day old to 28 d and the performances (feed intake, bodyweight, FCR, survival rates) were measured. Blood were taken from one bird per cage to measure the levels of monocyte, lymphocyte and heterophils. Results of the experiment showed that there was no significant (P>0.05) effect of treatments on the body weight, feed intake, and the survival rates during the 28 d trial. However, the BW and the survival rates of birds fed liquid bioactives and the AGP were higher than birds without feed additives. The FCR was significantly (P<01) affected by treatments. Best FCR was achieved when low level -liquid plant bioactives was supplemented followed by the AGP supplementation. Supplementation of plant bioactives in powder form did not show any benefit on the performance of the birds. The effectiveness of the bioactives in plant powder (or meal), although calculated to contain similar amount with the liquid (extract) may have been negate by other components in the plants. The monocyte, the lymphocyte and the heterophils level in the blood were not significantly (P>0.05) affected by treatments. Heterophils level in the blood has been used as an indication of the immunity in birds. This study showed that the highest level of heterophils was found in birds supplemented with high dose powder plant bioactives, which also have the lowest performance (including the survival rate). The results suggest that the roles of plant bioactives to replace AGP as feed additives and to improve the immunity of chickens needs a further study.