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. Litter size is one of the crucial factors in livestock production and is of high economic value, which is affected by ovulation rate, hormones, and growth factors. Growth factors play a multifaceted role in reproductive physiology. This review aims to investigate the association of bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9) with litter size in livestock. The transforming growth factor β (TGF- β) superfamily includes more than 34 members; GDF9 and BMP15 are among the most significant factors for regulating fertility and litter size in most livestock species. Ovarian follicles release BMP15 and GDF9 that are involved in the maturation of primary follicles into the basal form, proliferation of granulosa and theca cells, steroidogenesis, ovulation, and formation of the corpus luteum. Besides, these factors are highly expressed in oocytes and are necessary for female fertility and multiple ovulation in several livestock species. Animals with two inactive copies of these factors are sterile, while those with one inactive copy are fertile. Thus, the present review provides valuable information on the association of BMP15 and GDF9 with litter size in livestock that can be used as biological markers of multiple ovulation or for improving fertility in livestock.

A major environmental stressor for the poultry industry is heat stress, which results in substantial economic losses. Heat stress has recently garnered increasing public awareness and concern for its adverse effects on poultry welfare. Several physiological changes happen under heat stress, including oxidative stress, acid-base imbalance, and immunosuppression, leading to increased mortality and decreased feed efficiency, body weight, feed intake, and egg production. Reduced nutrient intake is a significant contributor to the reduction in growth performance in heat-stressed animals, perhaps because they consume less feed to reduce heat production. Hence, heat stress can be attenuated in poultry using several different strategies, each with varying degrees of effectiveness. Nanotechnology strategies have gained more attention and are found to reduce heat stress's detrimental effects. Nanotechnology focuses on creating materials with nano-sized particles that have improved physical, chemical, and biological properties. Also, nanotechnology can be used in poultry production to improve the ability of birds to absorb nutrients and, in turn, increase growth performance, nutrient digestion, and productivity. Therefore, this review provides scientific evidence regarding the adverse effects of high ambient temperatures on poultry health and performance and potential nanoparticle approaches to mitigate those detrimental effects and their challenges.

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Background: Nano-vitamins and minerals are used in animal nutrition to improve performance and health of broiler chickens as a potential alternative to antibiotic growth promoters. Objective: To evaluate the effect of several levels of a dietary nano α-tocopherol acetate plus selenium compound (NTS) on growth, intestinal histomorphometry, carcass traits, and immune status of broiler chickens. Methods: A total of 240 one-day-old Ross 308 chickens were randomly divided into four groups, each one with three pens (n=20 per pen). Four doses of nano α-tocopherol acetate and selenium (0, 5, 7, and 10 mg/kg) were included in the basal diet for 42 days. Results: Final body weight, cumulative body weight gain, and final conversion ratio significantly improved with increasing NTS levels (p<0.05). Carcass traits and weight of internal organs increased in the groups fed 7 and 10 mg/kg NTS. High NTS doses significantly increased immune vaccine titers against Newcastle disease, avian influenza virus, infectious bursal disease, and infectious bronchitis. Moreover, dietary addition of NTS improved intestinal morphometry. Conclusion: Thus, NTS (7 and 10 mg/kg) can be added to poultry rations to improve production, carcass characteristics, and immune status of broilers. Further studies are needed to evaluate NTS residues in meat.