Efecto de la adición de minerales en el agua o alimento sobre La frecuencia cardiaca, en pollos de engorde sometidos a estrés calórico crónico y agudo

the effects of mineral addition in feed or water on performance parameters and heart rate (hr) were evaluated in broilers at 28-35 d and？ 36 d under both chronic heat stress (chs) and acute heat stress (ahs) in laboratory conditions. one-hundred ninety two broilers were used, distributed in 6 cages and 4 rooms, according to weight, with 8 animals per cage: four males and four females. for individual measurements, at 21 d, 2 males and 2 females out of 8 broilers were chosen and classified as: heavy male; light male; heavy female and; heavy female. for hr measurement, 48 broilers were used. the assay included 3 treatments (t): t1: a basal diet (bd); t2: bd plus mineral addition in feed; t3: a bd plus mineral addition in water. the experimental design was completely randomized with 4 repetitions/treatment. composition of the mineral formula used was: nahco3 (0.83%); nh4cl (0.07%); nacl (0.30%), attaining a final balance of 240 meq/kg. the following was measured: feed consumption (fc), water consumption (wc) body weight gain (bwg), feed conversion efficiency (fce), body temperature (bt), hr, hyperventilation level (hl), blood ph, blood gases (bg), and blood electrolytes. the results were analyzed with anova and mortality rate (mr) was evaluated through the chi-square procedure. the results show that fc, bwg and fce were similar for all t. the wc for t2 (300±23.0 ml/bird/period) and t3 (290±19.0 ml/bird/period) was higher (p=0,016) than for t1 (220±12 ml/bird/period). the lowest m (15.63 % vs 37.50%) was found in t3 vs t1 (p<0.001). the hr and hl were not affected by t during chs and ahs. tachycardia was the result of ahs due to higher environmental temperatures. assessment of parameters such as cardiac output, blood pressure, stroke volume, total peripheral resistance, electrocardiogram wave morphology is advised to clarify cardiovascular function under heat stress.