The use of antibiotics to maintain animal well‐being, promote growth and improve efficiency has been practised for more than 50 years. However, as early as the 1950s, researchers identified concern on the development of resistant bacteria for the antibiotics streptomycin and tetracycline used in turkeys and broilers respectively. These findings laid the groundwork for agricultural officials to impose stricter regulatory parameters on the use of antibiotics in poultry feeds. Probiotics are live micro‐organisms included in the diet of animals as feed additives or supplements. Commonly known as a direct‐fed microbial, probiotics provide beneficial properties to the host, primarily through action in the gastrointestinal tract (GIT) of the animal. Supplementation of probiotics in the diet can improve animal health and performance, through contributions to gut health and nutrient use. For instance, supplementation of probiotics has been demonstrated to benefit farm animals in immune modulation, structural modulation and increased cytokine production, which positively affect the intestinal mucosal lining against pathogens. Bacillus subtilis has been a popular bacterium used within the industry and was shown to improve intestinal villus height. Increasing the villus height and structure of the crypts in the GIT allows for the improvement of nutrient digestion and absorption. Tight junctions maintain important defences against pathogenic bacteria and cellular homeostasis. Heat stress can be a major environmental challenge in the poultry industry. Heat stress causes the bird to fluctuate its internal core temperature beyond their comfort zone. To overcome such challenges, poultry will attempt to balance its heat production and dissipation through behavioural and physiological adaptation mechanisms.

This study investigated the antimicrobial and antioxidant activity of three Spirulina extracts (methanol, acetone, and hexane) and the biological selenium nanoparticles (SeNPs) fabricated by Bacillus subtilis AL43. The results showed that Spirulina extracts exhibited antimicrobial activity against tested pathogens. Besides, Spirulina extracts significantly scavenged ABTS and DPPH radicals in a dose-dependent manner. The methanolic extract had higher total phenolic content, antimicrobial activity, and antioxidant activity than other extracts. The selenium nanoparticles were synthesized by Bacillus subtilis AL43 under aerobic conditions and were characterized as spherical, crystalline with a size of 65.23 nm and a net negative charge of −22.7. We evidenced that SeNPs possess considerable antimicrobial activity against three gram-positive, three gram-negative bacteria, and three strains from both Candida sp. and Aspergillus sp. Moreover, SeNPs were able to scavenge ABTS and DPPH radicals in a dose-dependent manner. An association was found between the total phenolic content of Spirulina and SeNPs and their biological activities. Our results indicate that Spirulina and SeNPs with significant antimicrobial and antioxidant activities seem to be successful candidates for safe and reliable medical applications.

Insects could be a potential replacement of protein-rich ingredients in poultry diets. Among these insects, black soldier fly (BSF), Hermetia illucens, has a high content of protein and fat, which reinforces the potential of using it in poultry feed formulation and makes it one of the most promising insect species for commercial production. Protein content as well as amino acid profile in H. illucens larvae is comparable to those in many protein-rich feedstuffs such as fish meal and soybean meal. BSF can convert organic wastes into a precious source of nutrients, such as proteins, lipids, and chitin, which contribute to reducing the environmental burden and pollution potential arising from organic waste accumulation. This review emphasizes the significance of this insect as a “green” technology in the extremely variable recycling of organic waste and generates a sustainable protein source as well as the importance of its use as a substitute of protein-rich feedstuff in poultry feed manufacturing.

In the last two decades, poultry and animal industries became increasingly interested in using plant‐based feed supplements, herbs and their derivatives to retain or enhance their health and productivity. These health benefits for the host mainly attributed to the secondary plant metabolites, namely polyphenols. Polyphenols are renowned for their antioxidant, immunomodulatory, anti‐mutagenic and anti‐inflammatory properties. However, despite these advantages of polyphenols, they have been characterized by poor absorption in the gut and low concentration in target cells that compromise their role as effective antioxidants. The low bioavailability of polyphenols necessitates the need for further investigations to harness their full potential in poultry farms. This review is existing evidence about the bioavailability of polyphenols and their antioxidant, immunomodulatory, antimicrobial, detoxification properties and their impacts on poultry performance.

The removal of antibiotic growth promoters (AGPs) as feed additives in poultry nutrition from the market in many countries has compelled researchers to find unconventional and safe alternatives to AGPs. Probiotics, prebiotics, enzymes, organic acids, herbs, immune-stimulants and essential oils (EO) have been investigated as feed additives in poultry production. Cinnamon (Cinnamomum zeylanicum), one of the oldest medicinal plants and widely used around the world, can be used in poultry rations in the form of powder or essential oil. Essential oils produced from aromatic plants have become more interesting owing to their potential effects as hypocholesterolaemic agents, antioxidants, antimicrobials, antifungals and stimulants of digestive enzymes. The potential insecticidal and antimicrobial activities of EO against pathogens that cause spoilage in agriculture crops and human diseases might be attributed mainly to the high content of volatile components (mainly cinnamaldehyde, eugenol and carvacrol) in cinnamon oil. The present review focuses on the effects of cinnamon oil as a feed additive on poultry performance, carcass traits, meat quality, hypocholesterolaemic impact, antioxidant activity, immunity and microbiological aspects.