Nutritional manipulation to combat heat stress in poultry - A comprehensive review.

Global warming and climate change adversely affect livestock and poultry production sectors under tropical and subtropical conditions. Heat stress is amongst the most significant stressors influencing poultry productivity in hot climate regions, causing substantial economic losses in poultry industry. These economic losses are speculated to increase in the coming years with the rise of global temperature. Moreover, modern poultry strains are more susceptible to high ambient temperature. Heat stress has negative effects on physiological response, growth performance and laying performance, which appeared in the form of reducing feed consumption, body weight gain, egg production, feed efficiency, meat quality, egg quality and immune response. Numerous practical procedures were used to ameliorate the negative impacts of increased temperature; among them the dietary manipulation, which gains a great concern in different regions around the world. These nutritional manipulations are feed additives (natural antioxidants, minerals, electrolytes, phytobiotics, probiotics, fat, and protein), feed restriction, feed form, drinking cold water and others. However, in the large scale of poultry industry, only a few of these strategies are commonly used. The current review article deliberates the different practical applications of useful nutritional manipulations to mitigate the heat load in poultry. The documented information will be useful to poultry producers to improve the general health status and productivity of heat-stressed birds via enhancing stress tolerance, oxidative status and immune response, and thereby provide recommendations to minimize production losses due to heat stress in particular under the growing global warming crisis.

Assessment of In Ovo Administration of Bifidobacterium bifidum and Bifidobacterium longum on Performance, Ileal Histomorphometry, Blood Hematological, and Biochemical Parameters of Broilers.

Bifidobacterium is one of the most promising probiotics which was recently used as an alternative growth promoter in poultry. This trial was considered to evaluate the potential effects of in ovo administration of Bifidobacterium bifidum and Bifidobacterium longum on growth performance and biochemical parameters of broilers. Three hundred broiler breeder eggs were incubated and candled individually at day 17 of embryogenesis; then, eggs that had live embryos were randomly divided into six groups. The first and second groups were of intact (without injection) and vehicle-injected (sterile distilled water) control groups, respectively. Other groups were in ovo injected with 1 × 109 and 1 × 107 CFU B. bifidum, and 1 × 109 and 1 × 107 CFU B. longum, respectively. Hatchability was significantly (P < 0.001) affected by in ovo inoculation of bifidobacteria strains. Body weight gain and feed conversion ratio were significantly improved (P = 0.014 and 0.019, respectively) in all treatment groups. Protein fractions, aspartate aminotransferase, and alanine aminotransferase activities were not significantly altered by bifidobacteria strains in ovo injection. Regarding ileal histomorphometry parameters, a significant elevation in villus height and villus height/crypt depth ratio values were recorded while crypt depth was insignificantly affected by in ovo treatments. It could be concluded that the tested manual method of in-yolk sac injection at day 17 of incubation is more favorable in easier delivering of bifidobacteria strains which improve broiler growth performance and ileal development without any undesirable effects on blood indices and liver and renal functions.