ABSTRACT
This study aimed to determine the effects of the dietary supplementation of chromium methionine (CrMet) and ractopamine (RAC) on pigs in the growing-finishing stage under heat stress. The parameters evaluated included productive behavior, blood components, carcass characteristics, organ weight, and meat quality. This study was conducted during the summer season in Sonora, Mexico. The treatments included: (1) control diet (CON), a base diet (BD) formulated to satisfy the nutritional requirements of pigs; (2) RAC, BD plus 10 ppm RAC supplemented during the last 34 days of the study; (3) CrMet-S, BD supplemented with 0.8 ppm of Cr from CrMet during the last 34 days; and (4) CrMet-L, BD supplemented with 0.8 ppm of Cr from CrMet for an 81 d period. RAC supplementation improved the productive behavior and main carcass characteristics of the pigs compared with CON. However, RAC and CrMet supplementation during the last 34 days showed similar results in terms of weight gain, carcass quality, blood components, organ weight, and meat quality. The addition of CrMet-S had a moderate (although not significant) increase in productive performance and carcass weight. These findings are encouraging, as they suggest that CrMet may be a potential alternative for growth promotion. However, more research is needed.
ABSTRACT
FA dietary supplementation on the growth performance, carcass traits and histochemical characteristics of the Longissimus thoracis muscle from finishing pigs was investigated. Four hundred and twenty pigs were used in this study, and 105 animals (with five replicate pens and 21 pigs per pen) were assigned to one of four treatments: basal diet (BD) without additives (C-); BD + 10 ppm ractopamine hydrochloride + 0.97% lysine (C+); BD + 25 ppm of FA (FA); and BD + 25 ppm of FA + 0.97% lysine (FA-Lys). Dietary supplementation with FA or ractopamine increased both the average daily gain (14%) and loin muscle area (19%), while fat deposition decreased by 53%, in comparison with C- (p < 0.05). The growth performance of pigs treated with FA was similar to those of ractopamine (p > 0.05). The histochemical analysis showed that FA and C+ treatments induced a shift in muscle fiber types: from fast fibers to intermediate (alkaline ATPase) and from oxidative to glycolytic fibers. Muscle tissues from animals treated with FA or ractopamine had a lower cross-sectional area and a greater number of muscle fibers per area (p < 0.05). Findings regarding growth performance and carcass traits indicate that FA supplementation at 25 ppm without extra-lysine can replace the use of ractopamine as a growth promoter in finishing pigs.
ABSTRACT
Se tomaron 40 muestras de músculo Triceps femoral a las 24 h postmortem con un peso promedio de 5,7 g para evaluar el efecto del tipo de animal y el tiempo de almacenamiento sobre el porcentaje de pérdida por goteo en carne cruda. Las especies de animales evaluadas fueron pollo, res, cerdo, y avestruz. Sus carnes se almacenaron durante 24, 48 y 72 h a 0°C. Se realizó un análisis de varianza comparando medias por la prueba de Duncan. Los resultados indicaron que hubo diferencias (P<0,05) para el efecto tipo de animal, tiempo de almacenamiento y sus interacciones sobre la pérdida de agua por goteo en carne cruda. El mayor porcentaje de pérdida por goteo fue para la carne de res (P<0,05) seguido por la del cerdo, pollo y avestruz (2,1; 1,7 y 1,3 por ciento), respectivamente. A medida que se incrementó el tiempo de almacenamiento, aunmentó el porcentaje de pérdida (1,2; 1,9; 2,7 por ciento) a 24, 48 y 72 h, respectivamente. Se detectaron diferencias (P<0,05) en tipo animal x tiempo de almacenamiento, indicando que la pérdida de agua por goteo en la carne cruda de los distintos tipos de animales, se incrementó a medida que variaba el tiempo de almacenmiento. Se puede concluir que, al aumentar el tiempo de almacenamiento se ve incrementado el porcentaje de pérdida de agua en la carne cruda influenciado por el tipo de animal
