ISSUE FOCUS 48 FEED & ADDITIVE MAGAZINE June 2022 in microbial load compared to unsupplemented controls (p=0.01), thus improving their ability to resist opportunistic infection under heat stress. Different studies have demonstrated that the yeast postbiotic can reduce the effects of heat stress on poultry via hormonal modification. Sohail et al. subjected Ross 708 broilers to chronic severe heat stress (THI 33) for 42 days. At 21 and 42 days, circulating corticosterone concentration (biomarker of heat stress) was measured in control groups and those experiencing heat stress, either supplemented or not with 500 g/t Safmannan®. At both time points (Figure 2), the heat stressed control group had significantly higher corticosterone concentrations than negative control group and the heat-stressed-supplemented group (p<0.05). Postbiotic supplementation is therefore able to normalize corticosterone concentrations in heat stressed birds, thereby reducing the harmful effects of corticosterone on immunity and growth. Another study conducted in Mexico examined thyroid stimulating hormone (TSH) and T4 hormone levels in Cobb 500 birds under chronic severe heat stress conditions (THI = 33) either supplemented or not with 500 g/t postbiotic. At 35 days, compared to the control group, the birds in the yeast postbiotic group have significantly decreased levels of the regulator TSH and increased levels of the metabolic regulator T4 (p<0.05), thereby improving energy metabolism and growth. In Arbor Acres broilers, a trial in China (Figure 3) proved that 250 g/t Safmannan® supplementation throughout chronic heat stress (THI = 32) helped to significantly lower body temperatures by 0.5°C when measured at 42 days compared to unsupplemented birds (p<0.05). Furthermore, postbiotic supplementation also showed increased in daily weight gain comparable to non-heat stressed controls (p<0.05). THE GOLD-STANDARD YEAST POSTBIOTIC – KEY ELEMENT INTHE ARSENAL TO COMBAT HEAT STRESS Most of the projected growth in poultry production will occur in tropical zones spanning Asia, Africa, and Latin America, all of which are at a higher risk of heat stress. With global warming, heat stress becomes a very prominent issue affecting both bird welfare and producer economical profit. Anticipating heat stress by implementing integrated approach including housing, feeding regimes and nutritional strategies, ensures consistent production while maintaining animal living conditions to improve economic return. With a proven efficacy in plenty of studies performed worldwide, Safmannan® plays a key role in managing heat stress in poultry. The evidence provided above demonstrates that Safmannan® is a gold-standard yeast postbiotic both capable of shielding birds from the worst effects of heat stress, but also positively influencing production parameters via multiple mechanisms of action in reinforcing gut morphology and function and via hormone modulation. Figure 2. Effect of yeast postbiotic Safmannan® on corticosterone level under severe heat stress (THI = 33) Figure 3. Effect of yeast postbiotic Safmannan® on feed intake and growth under severe heat stress (D0 – D42, THI = 33)
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