The effect of dihydroquercetin on the growth and use of feed by pigs (Sus scrofa domesticus Erxleben, 1777) under moderate heat stress

Crossbred pigs are characterized by nervous instability, limited thermoregulation, and susceptibility to stress. Climate stress causes behavioral, physiological, functional, productive changes in farm animals. The aim of the research was to assess the influence of a moderate climatic stress factor (an increase in ambient temperature) on feeding, the digestibility of nutrients and productivity of intensively growing young pigs fed with dihydroquercetin (DHQ) during different periods of rearing and fattening (the physiological yard of the Ernst Federal Research Center for Animal Husbandry, 2020). For groups of crossbred boars F2 (Large White × Landrace) × Duroc, N = 36) were subjected to moderate heat stress (4-6 °С above the optimum). Control animals (group 1, n = 9) fed a basal diet (BD), group 2 ( n = 9) received BD + adaptogen dihydroquercetin (DHQ) during the rearing period, group 3 ( n = 9) during the rearing and fattening, and group 4 ( n = 9) during periods of technological stress (7 days after transportation, after transferring to other feeds, and before slaughter). The adaptogen we used as dietary supplement was Ecostimul-2 (LLC Ametis, Russia; 45 mg/kg of feed, or 32 mg DHQ/kg of feed). Moderate heat stress during feeding period (weeks 12-15 of the experiment) led to a significant increase in air concentration of ammonia up to 16.7 mg/m3, hydrogen sulfide up to 1.67 mg/m3, and carbon dioxide up to 0.14 mg/m3. The blood cortisol level was 291.60 nmol/l in control group 1 (or 23.0 % above the upper value of reference limits of 41-237 nmol/l), 299.89 nmol/l in group 4, and 210 nmol/l (p > 0.05) in groups 2 and 3. At slaughter, the cortisol level was the highest in the control animals (284.77 nmol/l) while feeding DHQ in groups 3 and 4 decrease it to 234-253 nmol/l. Adverse external stimuli increased the mortality in the control to 11 % vs. 0 % in other groups. The animals were weighed weekly, and the average daily weight gain was assessed for each of the periods as compared to control with regard to environmental factors (microclimate parameters) and technology elements (change of feed, vaccination, etc.). During the growing period, the weight gain in all groups with DHQ were 1.5-1.7 % greater than in control group 1 (week 1, group 3, p 0.05). In group 3 (32 mg/kg DHQ during the final fattening), there was a trend towards an increase in gross growth (by 6.2 %, 0.05 0.05; 2.87 g, p = 0.06) while its deposition in the body of growing young pigs was higher (by 3.52 g, p 0.05; 2.85 g, p = 0.06) in groups 2, 3, and 4, respectively. Calcium utilization was 9.82 % higher (p function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }