EFFECT OF OUTDOOR ACCESS ON ETHOLOGICAL BEHAVIOR, HEALTH AND PERFORMANCE OF BROILERS IN THE TROPICAL MEXICAN CONDITIONS

<p><strong>Background. </strong>There is a concern among poultry meat consumers due to broiler conditions during rearing period in commercial production systems. Consumers trust the organic and free-range poultry production systems because they suppose are more suitable and natural, giving high nutritive value and low-fat content to the meat, improving also the chicken welfare. <strong> Objetive. </strong> Two studies evaluated the effect of an outdoor access on ethological behavior, health indicators and productive performance of Hubbard broilers in the rearing period. <strong>Methodology. </strong> The first experiment evaluated outdoor access system in spring (april to may), and the second one was implemented in summer (june to august). In both studies included two groups: a) chickens with outdoot access (OA) and b) chickens at indoor rearing only (WOA). In the first experiment, ethological behaviors (EB) were described; forage intake (Fo), feed intake (FI), live weight gain (LWG) and carcass characteristics (Cc) were measured, blood components (BC), total immunoglobulins (Ig) and parasite eggs counts in excreta (Pc) were also determined, besides microscopic gut lesions in chickens (ML) were evaluated. In the second experiment, live weight gain (LWG), feed intake (FI) and forage intake (Fo) were measured, also carcass characteristics (Cc) were determinated. Analysis of variance by one way ANOVA was performed. <strong>Results. </strong> In first experiment, it was found that OA and WOA chickens stayed the most time resting. However, inside and outside, moving and foraging behaviors were observed in OA, while in WOA treatment foraging of chickens was the less frequent conduct. WOA showed higher final live weight and FI, but there were no differences in LWG and feed conversion in comparison with OA. Gizzard and caeca weights were heavier in OA treatment. No differences in both carcass yield and abdominal fat were found. At the last two weeks of age the forage intake amount per bird was 1.93 <span style="text-decoration: underline;">+</span> 0.97 g and 2.06 <span style="text-decoration: underline;">+</span> 0.87 g of DM/d of <em>Leucaena leucocephala</em> and<em> Pennisetum purpureum</em>,<em> </em>respectively. OA chickens had fewer leukocytes number (lymphocytes, eosinophils) and total inmmunoglobulins, but more heterophils and blood hemoglobulin. No differences between treatments in <em>Eimeria</em> oocysts in excreta were found. However, higher distribution and severity in microscopic gut lesions in birds WAO treatment were found. While in second experiment it was found that both OA and WAO broilers had similar final weight, feed intake, carcass yield and abdominal fat, but OA chickens had a trend to be higher in both weight gain and better feed convertion. Likewise, AO and WAO broilers had similar tibial ash content. Also, AO broilers consumed 0.50 <span style="text-decoration: underline;">+</span> 0.36; 0.49 <span style="text-decoration: underline;">+</span> 0.50 and 0.60 <span style="text-decoration: underline;">+</span> 0.32 g of DM/d of <em>Leucaena leucocephala</em>, <em>Brosimum alicastrum</em> and <em>Moringa oleifera</em>,<em> </em>respectivily. <strong>Implications. </strong> It is basic to have the knowledge regarding poultry production with outdoor access in tropical conditions. <strong>Conclusions. </strong> Outdoor access stimulated natural behaviours expression and did not affect productive performance. Also, AO did not produce hematological changes or severe microscopic lesions. </p>