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The continuous increase in poultry production over the last decades to meet the high growing demand and provide food security has attracted much concern due to the recent negative impacts of the most challenging environmental stressor, heat stress (HS), on birds. The poultry industry has responded by adopting different environmental strategies such as the use of environmentally controlled sheds and modern ventilation systems. However, such strategies are not long-term solutions and it cost so much for farmers to practice. The detrimental effects of HS include the reduction in growth, deterioration of meat quality as it reduces water-holding capacity, pH and increases drip loss in meat consequently changing the normal color, taste and texture of chicken meat. HS causes poor meat quality by impairing protein synthesis and augmenting undesirable fat in meat. Studies previously conducted show that HS negatively affects the skeletal muscle growth and development by changing its effects on myogenic regulatory factors, insulin growth factor-1, and heat-shock proteins. The focus of this article is in 3-fold: (1) to identify the mechanism of heat stress that causes meat production and quality loss in chicken; (2) to discuss the physiological, metabolic and genetic changes triggered by HS causing setback to the world poultry industry; (3) to identify the research gaps to be addressed in future studies.

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Probiotics serving as an alternative to the criticized antibiotics mainly focus on improving animal's growth and health. After realizing the dangers posed by diseases that have led to lots of economic losses, aquaculture scientists have sought the usage of probiotics. However, most probiotics are ineffective in eliciting aquatic animals' preferred effects, since they are from non-fish sources. Again, there are even a few marine aquatic probiotics. Given this, a study was conducted to investigate the probiotic potential of the bacteria species isolated from the digestive tract of hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂). Based on the morphological, biochemical, 16S rRNA sequencing analysis and evolutionary relationships, the isolated species were identified as Bacillus tequilensis GPSAK2 (MW548630), Bacillus velezensis GPSAK4 (MW548635), and Bacillus subtilis GPSAK9 (MW548634), which were designated as GPSAK2, GPSAK4, and GPSAK9 strains, respectively. Their probiotic potentials including their ability to tolerate high bile salt concentration, low pH, high temperatures, adhesion ability (auto-aggregation and cell-surface hydrophobicity), antimicrobial activity and biosafety test, compatibility test, hemolytic activity, and antibiotic susceptibility test were evaluated. While GPSAK2 and GPSAK9 strains were γ-hemolytic, that of GPSAK4 was α-hemolytic. All the isolates were resistant to low pH (1) and higher bile salt concentration (0.5%), showed higher viability ability after higher temperature exposure (80, 90, and 100°C), as well as higher cell-surface percentage hydrophobicity and auto-aggregation. All isolates exhibited positive compatibility with each other, signifying their ability to be used as multispecies. The three strains were susceptible to ampicillin (except GPSAK9, which was resistant), penicillin, kanamycin, ceftriaxone, chloramphenicol, erythromycin, clindamycin, furazolidone (except GPSAK2 and GPSAK9, which were moderately susceptible and resistant, respectively), polymyxin B, vancomycin (except GPSAK9, which was resistant), sulfamethoxazole (except GPSAK9, which was moderately susceptible), amikacin, minocycline, ofloxacin, norfloxacin, doxycycline, neomycin, gentamicin, tetracycline, carbenicillin, midecamycin (except GPSAK9, which was moderately susceptible), ciprofloxacin, piperacillin, and cefoperazone. All isolates demonstrated good antimicrobial activity against four pathogens, viz. Streptococcus agalactiae, Streptococcus iniae, Vibrio harveyi, and Vibrio alginolyticus. The results collectively suggest that Bacillus strains GPSAK2, GPSAK4, and GPSAK9 could serve as potential probiotic candidates that can be used to improve the growth and health status of aquatic animals, especially grouper.

A 56‐day growth trial was performed to dietary vitamin A (VA) requirement of Sillago sihama Forsskál (S. sihama) with an initial weight of 2.05 ± 0.15 g (mean ± SE). Quadruplicate groups of 40 juveniles per tank were fed with diets containing 362, 751, 1,141, 2,202, 4,335, 8,230, and 18,932 IU VA/kg diet respectively. Haemorrhages, erosion, greater mortality, and sluggish movement were found in fish of the control, whereas fish fed the 18,932 IU VA/kg diet appeared poor appetite. The weight gain rate (WG), specific growth rate (SGR) were highest at the level of 2,202 IU VA/kg diet, and the feed conversion ratio (FCR) showed the minimum at the same level. Compared with the control, groups 1,141–18,932 IU VA/kg showed significantly higher hepatic lysozyme (LZM) activity. Superoxide dismutase (SOD) at level of 751–4,335 IU VA/kg increased significantly than it in the control and reached a plateau after 4,335 IU VA/kg. Alkaline phosphatase (AKP) decreased significantly at level of 8,230–18,932 IU VA/kg diet than it in the control. Total antioxidation capability (T‐AOC), catalase (CAT), and glutathione peroxidase (GSH‐Px) in liver tended to increase and kept stable at level of 8,230 and 18,932 IU VA/kg diet. Fish fed 2,202 IU VA/kg diet showed significantly higher intestinal Na+‐K+ ATPase activity than it in other groups. The broken‐line model based on WG and maximum liver VA concentration indicated that the VA requirement was of 2,516 and 4,334 IU VA/kg respectively.