Dietary Hydroxy-Selenomethionine Helps Finishing Broilers to Cope with Heat Stress

The induction of oxidative stress by heat exposure, as well as the relationship between selenium (Se), selenoproteins and oxidative stress, is well described in the scientific literature (Habibian et al.,2015). Zhao et al. (2017) showed that hydroxy-selenomethionine (OH-SeMet) differently affected the expression of the selenogenome as compared to sodium selenite (SS). Hence, it was hypothesised that dietary supplementation of OH-SeMet may benefit heat stressed finishing broilers due to specific regulation of the selenogenome.

A total of 720-day-old male Ross 308 broilers was randomly assigned to 3 treatments (12 replicates; 20 birds each). Experimental diets were: no supplemental Se (NC), SS at 0.3 mg Se/kg and OH-SeMet at 0.3 mg Se/kg. A chronic cyclic heat stress challenge (temperature increased to 34°C for 6h, daily; RH = 50-60%) was applied in the finisher phase (25-39d; Akbarian et al., 2014). Growth performance parameters were recorded per pen. At day 39, in serum or plasma (one bird per pen), total Se, glutathione peroxidase activity (GPx) and triiodothyronine (T3) were measured.

In the finisher phase (Table 1), OH-SeMet significantly decreased FCR as compared to NC and SS (P = 0.026). Mortality, which increased substantially but not statistically significantly with cyclic heat stress, tended to be lowest in the treatment with OH-SeMet; 3.5 and 4.2% lower than NC and SS, respectively. Se supplementation significantly increased plasma total Se and OH-SeMet fed birds showed a higher level than SS fed ones (P < 0.001). GPx was significantly higher in Se supplemented diets but not different between OH-SeMet and SS. OH-SeMet significantly maintained serum level of T3 as compared to NC and SS (P < 0.01). In conclusion, compared with SS, OH-SeMet improved FCR of heat stressed finisher broilers, but it remains to be established whether differential effects on the expression of various selenoproteins might be involved.