Heat stress in poultry. II. Methods and techniques for prevention and alleviation

An adverse effect of heat stress in poultry depends on both the external factors such as diet, water supply, rearing technology, birds' population density, air humidity and flow rate, etc., and the internal factors, particularly, poultry species and breed specificity, physiological conditions, etc. Herein, the approaches to prevention and alleviation of heat stress in poultry are summarized and discussed. Different strategies were proposed for lowering of body heat production and for better heat dissipation, thus maintaining productivity and product quality and minimizing losses for poultry farms. These strategies include the increase in energetic level of a diet in accordance with decrease in feed consumption due to stress (N.J. Daghir, 2009) and inclusion of higher (up to 4-5 %) levels of fat (B.L. Red, 1981; N. Usayran et al., 2001; A.A. Ghazalah et al., 2008); decrease by 2-4 % of dietary crude protein (Q.U. Zaman et al., 2008) and carbohydrate levels (metabolization of fat produces less heat than protein and carbohydrates) (N.A. Musharaf, J.D. Latshaw, 1999; N.J. Daghir, 2008); changes in amino acid profile of a diet (diets imbalanced in amino acids may increase heat production; moreover, requirements in lysine and sulfur-containing amino acids are much higher in heat stressed poultry) (R.M. Gous, T.R. Morris, 2005; S. Syafwan et al., 2011; O. Vjreck, M. Kirchgessner, 1980); supplementation with additional 250 ppm of vitamin C (M. Ciftci et al., 2005; A. Kavtarashvili, T. Kolokolnikova, 2010), 200 ppm of vitamin E (Z.Y. Niu et al., 2009; A.A. Rashidi et al., 2010), 8000 IU/kg of vitamin A (H. Lin et al., 2002), minerals or proper premix of vitamins and minerals (V.I. Fisinin et al., 2009), supplementation of feed or drinking water with electrolytes NaHCO 3, KСl, CaCl 2, NH 4Cl (R.G. Teeter et al., 1985; T. Ahmad et al., 2005); pelleting of diets (R.M. Gous, T.R. Morris, 2005; A. Kavtarashvili, T. Kolokolnikova, 2010); special regimes of feeding (K. Hiramoto et al., 1995; M.H. Uzum, H.D. Oral Toplu, 2013) and intermitted lighting (A. Kavtarashvili, T. Kolokolnikova, 2010; D. Balnave, S.K. Muheereza, 1998); periodic (in 7-day periods) substitution of soda (NaHCO 3) for 50-80 % of dietary salt (P.S. Silva et al., 1996; A. Kavtarashvili et al., 2010); feeding of mixture of ground mussel and lime (1:1) from separate feeders with simultaneous decrease in dietary Ca level; inclusion of dietary enzyme preparations (V.I. Fisinin et al., 1999) and probiotic strains of Lactobacillus (P.T. Lan et al., 2004); the use of special anti-stress additives and preparations (P. Surai et al., 2012; Р. Surai et al., 2013); moistening of enzyme-supplemented diets (H. Lin et al., 2006; M.A. Khoa, 2007); increase in air velocity in poultry houses up to 2.0-2.5 m/s (J. Donald, 2000); tunnel ventilation systems (M. Czarick, B.L. Tyson, 1989); systems of evaporative air cooling (J. Donald, 2000; E.S. Mailyan, 2007); the use of heat-insulating and light-reflective roof materials, sprinkling of roof with cold water (S. Yahav et al., 2004); 15-20 % decrease in stock density (T. Ahmad et al., 2006); a decreased litter thickness (to 3-5 cm) (Salah H.M. Esmail, 2001); decrease in any disturbing activity (vaccination, repopulation etc.) during the hottest hours; providing poultry with constant access to water including days when poultry is vaccinated via water; elimination of spray vaccines during heat stress (O. Mikhailovskaya et al., 2010); regular cleaning and disinfection of drinking water and drinking systems; acidification of drinking water (A. Kavtarashvili, 2013); regular refilling of drinking system with fresh and cold water; isolation and shading of water tanks and pipes exposed to direct sunlight; cooling of drinking water (S. Yahav et al., 1996); thermal training of embryos during 2 nd half of embryogenesis (Y. Piestun et al., 2008) and 3-day chicks (S. Yahav et al., 2001; S. Yahav et al. 20