| Poultry productions continue to gain research interest due to the increasing global demands for chickens and poultry products.Chickens have fast growth rates,good economic turnovers,and they provide reliable sources of incomes.They are reliable sources of dietary proteins for rural households,especially in the tropics and subtropics.Broilers have narrow thermoneutral zones.High temperature and high humidity in the wet tropics increases heat stress in broilers.Heat stress causes adverse pathophysiological disorders and high morbidity and mortality in broilers.Heat stress is therefore more severe in broiler in the humid tropics.The ability of Chromolaena odorata to withstand harsh and warm climatic conditions in the humid tropics has been found to be due to the presence of its constituent phytochemicals.Polyphenols in C.odorata activates stress response transcription factors which enhances antioxidative enzymes.In this study,it was hypothesize that,C.odorata can enhance antioxidative enzymes in broiler birds to alleviate heat stress.It also has potential to enhance production performance,and immunity of bird at thermo-neutral condition,and heat stress conditions.We used ultrafine pulverization technology to prepare C.odorata ultrafine powder.Indigenous K902 broiler chickens were used for the study.The experiment was conducted in two stages: stage Ⅰ and stage Ⅱ.Stage Ⅰ was conducted in the starter-grower stage,and stage Ⅱ was conducted at the finisher stage.In stage I,day-old chicks were fed basal diet and C.odorata ultrafine powder at 0,0.3,0.6,and 1.2% dietary supplements at thermo-neutral conditions.Production performance index,and immune index were measured on day 28 and day 42.In stage Ⅱ,42–day old grower birds were fed 0,0.3,0.6,and 1.2% dietary supplements at heat stress conditions,and 0% COUP at thermos-neutral condition for 7 days and 14 days.Production performance,immune index,and heat stress response index were measure at day 7 and day 14.The results of the study were as follows.StageⅠ: Chromolaena odorata ultrafine powder(COUP)dietary supplement at 0.3-1.2%improved feed conversion efficiency(P<0.05),and body weight gain(P<0.05),but not feed intake(P≥0.05)at the starter-grower phase.0.3 and 0.6% COUP dietary supplements enhanced the immune index of liver(P<0.05),but not spleen(P≥0.05),and bursa of fabricius(P≥0.05).Likewise,0.3-1.2% dietary supplement of COUP enhanced serum immunoglobulin A(Ig A),and immunoglobulin M(Ig M).Stage Ⅱ: 14 days heat stress resulted in reduced feed intake but 7 days heat stress did not result in reduced feed intake.COUP supplementation at 0.6 and 1.2% enhanced feed intake(P<0.05)at the 7 days of HS whiles 0.3% COUP enhance feed intake at 14 d heat stress.Both 7 days heat stress and 14 heat stress increased the feed conversion ratio,however COUP supplementation reduced the feed conversion ratio(P<0.05)similar to birds in the thermal neutral conditions.Heat stress at 7 days and 14 days decreased the body weight gain.COUP dietary supplementation at 0.3,0.6,and 1.2% improved the body weight gain(P<0.05).At 7 day heat stress,0.6 and 1.2% COUP improved body weight(P<0.05)gain similar to the positive control(thermo-neutral)group,whereas 0.3% COUP improved body weight gain(P<0.05)similar to the positive control(thermo-neutral)group at 14 days heat stress.14 days heat stress resulted in decreased immune organ index for liver,but not bursa of fabricius,and spleen.0.6% of COUP dietary supplement improved the liver index(P<0.05)similar to the positive control(thermo-neutral)group.Body temperature of birds under heat stress for 7 and 14 days increased.1.2% COUP dietary supplement lowered the body temperature(P<0.05)for birds raised under 7 days,and 0.3,0.6,and 1.2% COUP dietary supplement lowered(P<0.05)the body temperature at 14 days heat stress.Serum catalase and serum superoxide dismutase were lower at 7 days,and 14 days of heat stress.COUP dietary supplements at 0.3 to 1.2% improved the anti-oxidant enzymes level and there were no significant differences(P≥0.05)between the COUP treated groups raised under heat stress and the positive control group raised under thermo-neutral conditions.Corticosterone and endotoxin levels in the serum was found to be significantly higher in birds raised under heat stress condition but not in birds raised under thermo-neutral conditions.COUP supplementations at 0.6% reduced(P<0.05)the serum endotoxin level at 7 days of heat stress.0.3,0.6,and 1.2% COUP supplementations reduced(P<0.05)the endotoxins level in the serum at 14 days heat stress.Serum corticosterone of birds raised under 7 and 14 days of heat stress were also reduced by 0.3,0.6,and 1.2% COUP dietary supplements.There were reduced heterophil/lymphocyte ratio in 7 days and 14 days heat stress in birds fed COUP dietary supplements.Heat stress increased the proinflammatory cytokines TNF-α and IL-β1and supplementing COUP at 0.3,0.6,and 1.2% reduced the proinflammatory cytokines.In summary,C.odorata ultrafine powder as an herbal feed additive at 0.3 to 1.2% of basal diet has potential to improve the performance,immunity,and enzymatic responses to heat stress in broiler chickens.Potential utilization of C.odorata as an immuno-nutritional supplement will enhance sustainable poultry productions especially in the tropics and sub tropics. |
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