As poultry producers face growing pressure to reduce antibiotic use while managing rising temperatures, a North-West University (NWU) study has found that combining probiotics and stimbiotics in broiler chicken diets could help the birds maintain growth and cope better with heat stress without compromising performance, meat quality, health or welfare.
The research, conducted by master's-degree researcher Millicent Mokonyama, investigated whether probiotics and stimbiotics could work together as an alternative to traditional antibiotic growth promoters in poultry, which are being phased out due to concerns about antimicrobial resistance.
“Antimicrobial resistance has become a global concern, creating the need to identify safer and sustainable alternatives that support poultry production,” Millicent said.
Her study involved 600 broiler chicks that were divided into five dietary groups over a six-week production cycle. While some birds received diets without antibiotic growth promoters, others were given diets with conventional antibiotic growth promoters. The birds were later exposed to controlled periods of heat stress to assess how the different diets affected their growth, health and behaviour.
The findings showed that birds fed probiotics alone, as well as those receiving the combination of probiotics and stimbiotics, recorded higher growth rates during the early stage of production than birds on other diets. More importantly, the combination did not negatively affect the health, meat quality, bone development or blood chemistry of the birds.
The study also found that diet influenced how birds responded to heat. Chickens receiving probiotics spent more time resting, while others showed different behaviours, such as seeking cooler areas and feeding during heat exposure. According to Millicent, these behavioural changes suggest that the dietary supplements helped birds respond more effectively to stressful environmental conditions.
“Our findings demonstrate that probiotics and stimbiotics can complement each other in improving the physiological and behavioural responses of broiler chickens exposed to cyclic heat stress,” she said.
The research further showed that birds receiving stimbiotics had lower cholesterol and triglyceride levels than those fed antibiotic growth promoters under normal conditions. The alternative diets also supported antioxidant activity, which is associated with maintaining meat quality.
Although some carcass characteristics and bone measurements differed between dietary groups, the overall results showed no harmful effects from replacing antibiotics with probiotics and stimbiotics.
Millicent said the findings are relevant for poultry producers looking for practical ways to improve productivity while reducing dependence on antibiotics.
“Including both probiotics and stimbiotics offers a sustainable feeding strategy that can improve growth, strengthen resilience to heat stress and contribute to responsible poultry production,” she said.
She added that adopting these alternatives could help producers maintain flock performance as climate change increases the frequency of heat stress events, while also supporting global efforts to reduce antimicrobial resistance in food production.
Millicent Mokonyama's study found that combining probiotics and stimbiotics in broiler chicken diets can improve growth and help birds cope with heat stress, offering a potential alternative to antibiotic growth promoters.
