Over the years, the growing concerns about the negative impact of anti-microbial growth promoters has triggered researches into the use of phytogenic feed additives in poultry production in order to ascertain better performance of birds as well as safety in the food chain. Phytogenic feed additives are compound derived from varieties of plants, its parts, extracts and essential oils which possess active substances that are of significant importance. Some of its functions include anti-microbial and anti-oxidative effects on the poultry feeds and carcass as well as enhancement of flavour of feeds. Despite the beneficial influences of PFAs, numerous controversial issues have emerged on the appropriate dosage to be used in poultry production. This may be due to the differences in edaphic and climatic actions on plants available in various part of the world and stage of harvesting of plants which makes standardizing inclusion levels of phytogenic feed additives in poultry diet seemingly difficult. However, it is crystal clear that phytogenic feed additives qualify as a better substitute to anti-microbial growth promoters as it is safe and ecologically friendly.

In renewable system, to improve growth performance and enhance the stability of broiler meat may be alternative dietary garlic and its derivatives. The effects of dietary fresh garlic extract (FGE) or aged garlic extract (AGE) supplementation on performance, serum cholesterol and meat thiobarbituric acid (TBA) values and the organoleptic traits of cooked meats were investigated using 540 one-day-old Ross 308 broilers. Treatments: negative control (NC, basal diet), positive control (E200, basal diet + 200 mg vitamin E kg-1), FGE (FGE10, basal diet + 10 ml FGE kg-1) and graded levels of AGE (AGE5, AGE10 and AGE15, basal diet + 5, 10 and 15 ml AGE kg-1, respectively). Sensory appraisal was used to establish the consumer acceptability of boiled, grilled or roasted meats. FGE10 increased weight gain compared to NC, AGE5 and AGE10, whereas FGE10, E200 and AGE decreased serum cholesterol and meat TBA levels compared to NC. The alleviating effects of FGE10, AGE5 and AGE10 were higher than that of vitamin E. All garlic extracts did not affect the colour and nutritional quality of raw meat. Overall consumer acceptance of meat increased by FGE10, while it decreased by AGE10 and AGE15 compared to NC. Sensory scores of grilled meat were higher than for boiled and roasted meats. These results indicate that FGE proved an advantage for sustainable broiler production due to improve in the growth performance and consumer acceptance of cooked meat.

Genetically modified (GM) crops are being planted at large scale worldwide. In most of the countries, GM crops are processed into livestock feed. The land is used for cultivation of GM plants has been increased in recent years; in 2012 GM plants were grown on over 170 million hectares in 28 countries by 17.3 million farmers and extended to 185.1 million hectors in 2016 worldwide. GM plants have been used as feed for animals and the number of studies has proved their safety for animal and public health. This paper reviews the possible effects of GM crops on livestock, poultry, and aquatic animals by reviewing different type of studies, in which parameters such as performance, reproductive and health assessment were investigated. The most of peer-reviewed papers evaluating the effects of feeding animals with transgenic crops were based on GM plants with improved agronomic traits i.e. herbicide-tolerant plants and pets-tolerant plants; however, in some cases GM plants with boosted nutritional properties assessed. In most experiments, either Bt (Bacillus thuringiensis) maize, Roundup Ready (RR) soybean or both fed to animals. Measurable differences in various parameters were mostly observed in Bt maize and soybean fed separately or simultaneously to animals. In this review, scientific studies showing the effects of the use of GM products in the nutrition of domestic animals on performance, health and reproductive parameters are investigated.