Poultry are particularly sensitive to temperature-associated environmental challenges, especially heat stress. With the hot summer months approaching fast, it is good to refresh your memories as to what heat stress causes and the detrimental effect it can have if not managed properly.

• Modern poultry genotypes produce more body heat, due to their greater metabolic activity. (Settar, et al.,1999. Deeb, et al., 2002)
• Birds subjected to heat stress conditions spend less time feeding, more time drinking and panting, as well as more time with their wings elevated, less time moving or walking, and more time resting. (Mack, et al., 2013)
• Increased panting under heat stress conditions hampers blood bicarbonate availability for egg shell mineralization and induces increased organic acid availability, also decreasing free calcium levels in the blood. This affects egg shell quality in breeders and layers. (Marder, et al., 1989)
• Heat stress can disrupt the reproductive hormones in hens, leading to reduced levels and functions. In males, semen volume, sperm concentration, number of live sperm cells and motility decreased. (Donoghue, et al., 1989. Novero, et al., 1991. Rozenboim, et al., 2007. lnagar, et al., 2010)
• Heat stress alters the activity of the neuroendocrine system of poultry, which affects body temperature and metabolic activity. Endocrinological changes caused by chronic heat stress in broilers also stimulate lipid accumulation. (Garriga, et al., 2006. Star, et al., 2008. Quinteiro-Filho, et al., 2010 and 2012. Geraert, et al.,1996)
• Heat stress has immunosuppressing effects on broilers and laying hens. Broilers had lower levels of total circulating antibodies, as well as lower specific immunoglobulin levels. (Bartlett, et al., 2003)
• Broilers subjected to chronic heat stress showed significantly reduced feed intake, lower body weight, and higher feed conversion ratio. Also impaired growth performance in broilers subjected to heat stress. (Imik, et al., 2012)
• Chronic heat exposure negatively affects fat deposition and meat quality in broilers. Protein content was lower and fat deposition higher in birds. (Lu, et al., 2007. Zhang, et al., 2012)
• Studies showed reductions in feed intakes, egg production, feed conversion and egg weights, reduced egg shell thickness and increased egg breakages in layers. (Deng, et al., 2012. Star, et al., 2009. Lin, et al.,2004)
• The gastrointestinal tract is particularly responsive to heat stress, causing alteration of the protective microbiota and decreased integrity of the epithelium. Heat stress can modify biological defense systems, such as antibody and cell-mediated immune responses, thereby increasing susceptibility to pathogens. (Collins, et al., 2012. Dinan, et al., 2012. Wei et al., 2013)
• Heat stress has been shown to cause increased intestinal permeability in broilers, and changes in the microbial structure. Mucosal attachment of Salmonella Enteritidis increased when tissues originated from heat-stressed birds. Also morphological changes in the intestinal tract of laying hens, consisting of decreased villus height and ratio of villus height to crypt depth. (Garriga, et al., 2006. Burkholder, et al.,2008. Bozkurt, et al., 2012. Deng, et al., 2012)
• Oxidative stress is the starting point of the intestinal permeability dysfunctional process which facilitates translocation of bacteria from the intestinal tract. Increased inflammation and translocation of Salmonella Enteritidis in broilers subjected to heat stress has been reported. (Quinteiro-Filho, et al., 2010 and 2012)
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Our data base is in its infancy regarding the use of Xtract 6930 and its potential to reduce the effects of heat stress in poultry. We however believe it is worth taking note of our colleagues experiences world-wide and hope this will find value with you.