Influência de diferentes modelos de instalações de frango de corte e ambiência de luz pré-abate sobre o bem-estar animal e qualidade de carne

Abstract

The objective of this work was to evaluate the animal welfare under broilers chickens different raising installations models at the farm and also the effect of light ambience at the moments just before birds slaughtering and their consequences on the meat quality. This Dissertation was divided into 3 phases using Cobb lineage at 46 days old: 1.Birds grown in dark house (T3) in comparison to broilers conventional housing covered by yellow (T1) and blue courtains (T2). The 27 lots were divided into three treatments (n = 9) in the evaluation of production performance for the following parameters: feed conversion, average daily gain, final weight, viability and podal callus. Among these 27 lots, 9 were chosen for poultry welfare evaluation related to the final meat quality, as measured by the incidence of PSE meat and this step being performed in a commercial slaughter plant. The animals (n = 630) were divided into three treatments (n = 210), 70 birds per aviary, randomly chosen, the fillets were collected 24 h post mortem and analyzed for pH and color (CIELab system). The program Statistica for Windows 7.0 was used to analyze the results. The Tukey test probability (p ≤0.05) was applied for comparing the animals performance. The values obtained in the assessment of animal welfare and meat quality were analyzed by multivariate Principal Component Analysis (PCA). The obtained results for the chickens production performance showed that the dark house system showed better feed conversion (1.75) (p ≤0.05) compared to T1 and T2, which did not differ to each other (p≥ 0.05) in values of 1.82 and 1.80, respectively. Broilers raised in the dark house systems have a higher average daily gain (63.14g) and consequently tended to have higher mean final weight (2904.8g) differing from other treatments T1 and T2 (p≤0.05). They showed no significant difference (p 0.05) to each other and the average daily gain of 56.68g and 57.79g, respectively consequently lower final body weights of 2.607 and 2.658 kg, respectively. However, the percentages of podal callus differed in all treatments (p ≤0.05), T1 showed the lowest % of callus (4.55) compared to T2 (8.98) and T3 (20.98). There were no significant differences (p≥0.05) on the viability for poultry produced in conventional and dark house aviaries. The values obtained in the assessment of animal welfare and meat quality contrary to the expectations, presented a higher incidence of PSE meat. The reason is probably because of the stressful conditions that birds suffered during handling for transportation when for the first time these birds were exposed to light and subsequently to transport and treatment conditions at the commercial plant. In conclusion, the dark house systems had higher potential for production with superior performance in relation to conventional systems except in relation to callus podal and a higher incidence of PSE meat. 2. In the second phase, the objective was to investigate the effect of the ambience illuminance at the moment before slaughter on the chickens stress measured by the incidence of PSE meat. The experiment was conducted in a commercial plant in the springtime season in the southern region of the country. The birds (n = 200) were divided into two groups before slaughter at the time of hanging: Treatment with higher (290 lux) and lower illuminance (160 lux). Fillet (Pectoralis major m.) samples were collected 24 h post mortem and analyzed for pH and color. Samples from the group with higher illuminance had lower meat quality with lower pH value, showing that higher illuminance during hanging generated a discomfort zone with the consequent increase in birds stress. The decrease of illuminance at the moment before slaughter had an important role in reducing the stress ante-mortem and promoted a decrease of 7% incidence of PSE meat. 3. In the third phase, the objective was to investigate the effect of illuminating colors and the colors spectral distribution just before slaughter on the broiler chickens welfare measured by the incidence of PSE meat. The experiment was conducted in a commercial plant in the spring season in the southern region. The birds (n = 400) were divided into four treatments before slaughter at the time of hanging as: blue, green, red and white lights ambience. Fillet (Pectoralis major m.) samples were collected 24 h post mortem and analyzed for pH and color and classified as normal and PSE meat. Samples from chickens under white light treatment presented lower pH values indicating that the absence of a faint source of light at the step of birds hanging generated a discomfort zone with consequent increase in stress. The use of blue, green and red lights at the moments before slaughter had important role in reducing the ante-mortem stress and decreased by 19%, 21% and 16%, respectively, the incidence of PSE meat.