EFFECTS OF LIVE YEAST (Saccharomyces cerevisiae) SUPPLEMENTATION AND DIFFERENT NUTRIENT DENSITY DIETS IN GROWING-FINISHING PIGS UNDER HEAT STRESS

Growth performance and health status in three successive feeding phases (FI, FII and FIII, corresponding to 22-60, 60-90 and 90-113kg of body weight, respectively), carcass characteristics and feed cost per kg gain by effects of different nutrient densities and of supplementation with live yeast, were evaluated in 60 growing-finishing pigs housed under severe heat stress conditions. Three experimental dietary treatments were compared: a positive control (TP) diet formulated to satisfy the total nutritional requirements in summer; a negative control (TN) formulated to have a reduced nutrient density; and a yeast control (SC) diet that consisted of TN supplemented with yeast (0,7kg/ton). In FI, pigs fed the SC diet had a better feed conversion ratio (CA) than those under the TP diet (P<0,05). In FIII, SC resulted in a higher average daily feed intake (CDA), average daily gain (GDP) and average of body weight (P<0,05) compared to TN. In FI, pigs fed TN showed the greatest incidence of mild diarrhea, followed by the TP (P<0,05). In FII, pigs fed the TN showed the highest incidence of slight respiratory disease (cough), compared to TP and SC (P<0,05). Carcass characteristics were not modified (P>0,05). The feed cost per kg of weight gain was decreased with the SC compared to TP (P<0,05). In conclusion, supplementation with live yeast during high heat stress improved growth and health and reduced feed cost per kilogram gain.