Role of dietary zinc in heat-stressed poultry: A review

Abstract

High ambient temperatures compromise performance and productivity through reducing feed intake and decreasing nutrient utilization, growth rate, egg production, egg quality, and feed efficiency, which lead to economic losses in poultry. Environmental stress also leads to oxidative stress associated with a reduced antioxidant status in the bird in vivo, as reflected by increased oxidative damage and lowered plasma concentrations of antioxidant vitamins (e.g., vitamins E, A, and C) and minerals (e.g., Zn). Zinc has an important role in numerous biological processes in avian and mammalian species. For instance, Zn is an essential component of many enzymes, and it has both structural and catalytic functions in metalloenzymes. Furthermore, dietary Zn is required for normal immune function as well as proper skeletal development and maintenance. One of the most important functions of Zn is related to its antioxidant role and its participation in the antioxidant defense system. This work compiles past and present information about the role of Zn in heat-stressed poultry health.

Welfare improvement in laying hens during the hot period under a semi-open rearing system through dietary arginine and vitamin C supplementation

“…In birds with induced stress Puvadolpirod & Thaxton (2000a,b,c) reported higher blood plasma cholesterol and lower total protein concentrations. The heat stress in our experiment was manifested with significantly lower number of feeding, egg-laying, feather-cleaning, dust bathing and mating birds but increased number of drinking and resting control birds, compared to the thermoneutral period, which are criteria for welfare worsening in birds (Ensminger et al, 1990;Sahin et al, 2009;Bozakova et al, 2012). Similar results for decreased egglaying during a hot period in breeder hens are reported by Star et al (2008) and Yardibi & Turkay (2008).…”

“…Our data are in agreement with those reported by Popova-Ralcheva et al (2002), Sahin et al (2005;, affirming that during heat stress, corticosterone, adrenaline and glucagon are primary regulators of blood glucose in birds and providing evidence for increased serum glucose, cholesterol and creatinine. The experiments of Star et al (2008) and Sahin et al (2009) demonstrated statistically significantly higher blood corticosterone, glucose and reactive oxygen species in four strains of laying hens. In birds with induced stress Puvadolpirod & Thaxton (2000a,b,c) reported higher blood plasma cholesterol and lower total protein concentrations.…”

“…It is a common cause of welfare worsening in hens triggering a chain of non-specific reactions and systemic mechanisms of defense. The stress in birds is mediated mainly by activation of the hypothalamic-pituitary-adrenal axis, the orthosympathetic nervous system and poultry behaviour changes (Puvadolpirod & Thaxton, 2000a,b,c;Sahin et al, 2009). In heat stressed birds, the hypothalamus activates adrenal gland cortex and it reacts by enhanced secretion of glucocorticoids -corticosterone (Puvadolpirod & Thaxton, 2000a,b,c).…”

“…The thermoregulation in birds is difficult because of the high body temperature (41.5 o C) and limited heat exchange mechanisms at that time. The primary mechanism for heat loss is through evaporation from mucous coats during accelerated respiration (Ensminger et al, 1990;Sahin et al, 2009). Other behavioural traits include more frequent drinking, looking for shady places to hide etc.…”

The expression of heat shock protein 70 gene with organic selenium supplementation and its effetc on productivity of broilers in tropical environment

“…Heat stress also leads to oxidative stress associated with a reduced antioxidant status in the bird in vivo, as reflected by increased oxidative damage and lowered plasma concentrations of antioxidant vitamins and minerals (Sahin et al, 2009). Therefore, the addition of antioxidant into diet is to increase the activity of antioxidant enzyme which acts to protect the body from oxidative damage caused by free radical (Rusli et al, 2015).…”