Heat stress in poultry and the beneficial effects of ascorbic acid (vitamin C) supplementation during periods of heat stress

Pakistan is an agro-livestock based economy with a poultry share of 55% of the total agricultural GDP (21%). The environment in Pakistan remains hot and humid during July to August, which renders the survival of poultry critical during these months, as birds are more susceptible to changing environments than other domestic animals. Heat stress is a combination of high environmental temperature and humidity, hindering proper thermoregulatory processes. It diminishes immunity, feed intake, weight gain, egg production, number of chicks per hen, hatchability of fertile eggs, egg and carcass quality, mineral balance, and increases panting and mortality and affects semen quality and fertility in male birds. Ascorbic acid (vitamin C), a white crystalline compound (also known as L-ascorbic acid) is primarily synthesised in the chicken by the kidneys, however, during heat stress, endogenous ascorbic acid becomes insufficient to meet the bird's requirements. Vitamin C ameliorates heat stress induced problems such as poor immunity, feed intake, weight gain, oxidative stress, rectal and body temperature, fertility and semen quality, carcass weight and mortality in birds.