Feeding broiler chickens high levels of the microalga Chlorella vulgaris, combined with an enzyme superdose, can improve their nutritional and meat quality.
Research by scientists in Portugal also showed that extrusion, a process using heat and pressure to break down algal cells, is an effective processing method to get the most out of the alternative feed.
Testing Chlorella diets against conventional soy–maize feed
The team carried out their study in two phases: first, a microalgae digestibility study, in which they precision-fed the birds untreated and extruded C. vulgaris and then collected the contents of their digestive system 42 hours after feeding. Then, they conducted a feeding trial, in which they initially fed all the birds a standard soybean-maize diet for two weeks, then split the birds into four diet groups:
- Control, continuing the soybean-maize diet
- 15% sprayed, dried C. vulgaris powder
- 15% C. vulgaris with 0.3% pancreatin, an enzyme
- 15% extruded C. vulgaris
The scientists analysed food intake and weight gain to calculate feed conversion ratio, recorded data on the birds’ beak condition and excrement and after slaughter, used several metrics to calculate meat quality. They also carried out a full nutritional analysis of the different feeds.
They found that extrusion of the alga resulted in more available energy and key amino acids, backing up similar findings seen in previous studies. However, these changes did not result in growth outcomes in the later feeding trial.
Enzyme superdose counters minor beak condition issues
From feeding the birds the diets, they saw that including the microalga at 15% had no effect on growth compared to the conventional diet, and that extrusion improved growth performance of the feed.
One issue with the diets including the microalga was that it had a minor negative impact on birds’ beak condition, with food accumulating on their beaks more. However, using the superdosed enzyme mitigated the problem.
Meat quality improves with microalgae inclusion
Their analysis also showed that meat from the birds fed C. vulgaris was higher quality than the control group, with a healthier profile of fats, higher mineral content and improved colour.
“This study demonstrated that C. vulgaris could be an alternative feed ingredient for broilers without compromising growth performance, animal welfare, and meat quality,” the researchers wrote in the journal Poultry Science. “Even the untreated C. vulgaris diet produced comparable results to a conventional maize-soybean diet.”
They noted the potential health benefits of meat from chickens fed the alga, and its role in improving the sustainability of poultry feeds. However, they added that further work should look at optimising inclusion rates, clarifying the need to processing and assessing economic viability of the novel approach.
Key takeaways
- Chlorella diets maintained broiler growth while improving meat fat profile, minerals and colour.
- Extrusion increased energy and amino acid availability in microalgae feed.
- Enzyme superdose reduced beak-clogging issues caused by Chlorella diets.
- Untreated and extruded microalgae performed comparably to conventional soy–maize feed.
- Researchers highlight sustainability potential but call for economic and optimisation studies.
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