| dc.description.abstract | Los consumidores demandan procedimientos de matanza de conejos en condiciones de bienestar que garanticen carne de calidad, como el uso de métodos de aturdimiento, los cuales han sido poco evaluados en México debido a la producción de esta especie principalmente en pequeña escala. El estudio se basó en una muestra de 120 conejos California, de ambos sexos, con un promedio de 2 kg de peso y 65 días de edad, usando los métodos de concusión y electronarcosis previo a la matanza. Se plantearon tres objetivos a manera de capítulos: Capítulo1. Objetivo: relacionar el efecto de dos métodos de aturdimiento y sexo, evaluando las manifestaciones de conductas durante el aturdimiento y degüello, lesiones en canal y factores que afectan el bienestar animal (BA). Se empleó un Diseño Completamente al Azar con arreglo factorial 2 x 2, se obtuvieron factores de riesgo de lesiones y las conductas fueron comparadas con U-Mann-Withney y Kruskall-Wallis. Los resultados mostraron que la electronarcosis produce mejores condiciones durante la matanza y mayor BA que la concusión. Capítulo 2. Objetivo: comparar el efecto de dos métodos de aturdimiento en las características de la canal y las propiedades fisicoquímicas de la carne. Se registraron el peso vivo, canal caliente y fría, pH (1, 24 y 48h) en Biceps femoris; color, capacidad de retención de agua (CRA) y resistencia al corte (RCort) en Longissimus dorsi. Se compararon los métodos de aturdimiento y sexo usando PROC GLM (SAS Inst. Inc., Cary, NC). La calidad de carne se analizó con pruebas no paramétricas. No se encontraron diferencias entre sexos (p>0.05), existieron diferencias en la canal caliente favoreciendo a la electronarcosis (p<0.05). Hubo diferencia en el pH1h (p<0.05), pero no en el pH24h ni en la resistencia al corte de la carne (p>0.05). El método de electronarcosis originó carne más oscura y amarilla (L* y b* p<.0001) y con mayor CRA (p=0.049), que el método de concusión. El método eléctrico produce menor estrés en el ante mortem en los conejos que la concusión, pero no influye en la calidad de la carne. Capítulo 3. Objetivo: caracterizar la canal del conejo despiezada e identificar la importancia relativa de sus partes. La canal fue despiezada a las 24 h post mortem; se registró el peso de la canal fría (PCF), cabeza (CBZ), brazos (BRZ), piernas (PRN), lomo (LOM), espaldilla (ESP), tórax (TOX), faldilla (FAL), hígado (HIG) y riñones (RIS). Los datos fueron analizados usando correlaciones de Pearson, Análisis de Componentes Principales y Conglomerados. Los resultados mostraron que el 72 % de la variación en la canal lo explican cuatro componentes (CP). El CP1, explicó el 37 % de la variación total, y lo conformó el PCF, CBZ, PRN y LOM; el CP2, explicó el 16% con las variables BRZ, TOX y FAL; el CP3, con el 11% y conformado por RIS; y el CP4, 8% constituido por HIG y ESP. El análisis de conglomerados permitió identificar dos grupos (CLU) de conejos, diferenciados por el peso de las partes que integran la canal. _______________ EFFECT OF TWO STUNNING METHODS ON WELFARE INDICATORS IN CALIFORNIA RABBITS. ABSTRACT: The demand for slaughter practices to be carried out under conditions of welfare, and that guarantee quality meat products, is growing among consumers. In Mexico, diverse methods for stunning rabbits before slaughter are available. However. such methods have been poorly evaluated, since rabbit farming takes place mainly in small-scale production units. The present study was based in a sample of 120 California rabbits, including both sexes, with an average weight of 2 kg and 65 days of age. Electrical stunning and manual stunning method were used before slaughter. Three objectives were determined in the form of chapters. Chap.1. Objective: To relate the effect of two stunning methods and gender by evaluating the manifested conducts, lesions in the carcass and the factors that contribute to animal welfare (AW) during stunning and slaughter. A completely randomized 2x2 factorial design was used, risk factors for the lesions were obtained and the conducts were compared with a Mann-Whitney test and Kruskall Wallis test. Results indicate that electrical stunning before slaughter resulted in better AW conditions than manual stunning. Chap.2. Objective: To compare the effect of two stunning methods for rabbits in the characteristics of the carcass, as well as in the chemical and physical properties of the meat. Live-weight, warm-carcass weight and cold-carcass weight were registered; pH (1, 24 and 48h postmortem) was measured in Biceps femoris; and the water holding capacity (WHC) and meat tenderness, i.e., Shear force test, were evaluated in Longissimus dorsi. The stunning methods and gender were compared with PROC GLM (SAS Inst. Inc., Cary, NC). Meat quality was analyzed with nonparametric tests. No difference was found between gender (p>0.05). However, the stunning methods were different in the warm-carcass favoring electrical stunning. pH1h was different (p<0.05), while pH24h and meat tenderness showed no difference in relation to the stunning method (p>0.05). Electrical stunning generated meat that was less bright and with a yellow tone (L* and b* p<.0001), with a higher WHC (p=0.049). In general, results demonstrated that electrical stunning in rabbits generated less stress prior to slaughter and improved some meat characteristics. However, no influence was found in the quality of the meat. Chap.3. Objective: To characterize the cut rabbit carcass and to identify the relative importance of the cuts. Carcasses were cut 24 h postmortem; the weight of the cold-carcass (CCW), head (HE), arms (AR), legs (LE), back (BA), shoulder (SH), thorax (TH), belly flaps (BF), liver (LI) and kidneys (KI) were registered. Data were analyzed with Pearson correlations, principal component analysis, and cluster analysis. Results demonstrated that 72% of the variation in the cuts was explained by four principal components (PC). PC1 explained 37% of the total variation including CCW, HE, LE and BA; PC2 explained 16% of the variation with variables AR, TH and BF; PC3 explained 11% of the variation with KI; and CP4 explained 8% of the variation with LI and SH. The cluster analysis permitted to pinpoint two groups (CLU) of rabbits with different weight in the cuts that conform the carcass. | es_MX |
