Programas nutricionais de selênio para o enriquecimento de carnes de frangos de corte e suínos

Abstract

The nutritional importance of selenium (Se) has been investigated at several areas of biology, whether in the human, animal or plant area. Until half of century XX this mineral trace was studied only by its toxic capacity, however, however, at the moment i t is known of its important contribution for the maintenance of the oxidative balance by means of the activation of systems that fight free radicals harmful to the cells. Recent studies have shown that biocomplexes sources have a higher bioavailability and, therefore, better deposition in some animal tissues, contributing to the maintenance of health and increase in meat quality of both broilers and pigs. Nevertheless, the great limitation for its use is the high cost with respect to the sodium selenite, commonly used in animal feeds. The objective of the present study was to evaluate the effect of the use of Se biocomplexed sources on performance, tissue deposition and meat quality of broilers and pigs in finishing phase. Four experiments were conducted at the Animal Science Department of the Federal University of Lavras. At the first experiment, 2100 Hubbard Flex day male chicks were distributed in a completely randomized design in 12 treatments, with seven replicates, totalizing 84 experimental pens. The treatments consisted of supplementation of Selenomethionine (SM-1600 ppm) at levels of 0.3 and 0.5 ppm in replacement of sodium selenite (SS-45.7%) in different pre-slaughter phases. At the second experiment, 224 day-old male Hubbard Flex chicks were randomly distributed in 28 metabolic cages. The birds were distributed in four treatments with seven replicates of 8 birds each in the experimental period of 1-21d and experimental pens with 4 birds each in the period of 22-42 days of the birds. The treatments consisted of four inclusion levels of SM (0.3, 0.4, 0.5 and 0.6 ppm). Were evaluated in both experiments: the performance (1-21 and 1-42 days), carcass and cuts yield, apparent retention of Se (33-35 days), physicochemical characteristics of breast meat: objective color, drip loss (DL), cooking loss (CL), pH, peroxide index (PI); and tissue Se deposition in breast and liver. The third experiment , were used 1200 male Cobb 500 day-old chicks, randomly distributed in four treatments with 10 replicates each. The treatments consisted of two sources of Se-yeast (3000 ppm and 2000 ppm), an inorganic source (sodium selenite, 45.7% Se) and the combination between the inorganic source and Se-yeast 3000 ppm. The diets were based on corn and soybean meal and for all treatments the inclusion of Se was 0.3 ppm. Performance indices were determined from 1 -21 and from 1-42 days. At 42 days two birds per pen were slaughtered to determine the carcass and cuts yield. Breasts and livers were collected for determination of physicochemical characteristics of breast meat and tissue deposition of Se and a blood sample was collected from the birds for determination of GSH-Px activity. At the fourth experiment were used 64 male neutered hybrid pigs (PICxPIC), distributed in randomized blocks according to body weight in 8 treatments and 8 replicates, each animal being an experimental unit. The treatments consisted of two Se levels from the Sodium Selenite (SS - 0.3 and 0.6 ppm), four Se levels from Selenomethionine (SM - 0.3, 0.4, 0.5 and 0.6 ppm) and two combinations of SS with SM (SS 0.15 + SM 0.15 ppm and SS 0.3 + SM 0.3 ppm). The diets were based on corn and soybean meal supplemented with vitamins and minerals. Were evaluated the performance, cold carcass yield, the physicochemical characteristics of the meat loin and Se tissue content in muscle and liver. It was observed that the level of SM no effect on the performance of broiler chickens and swine in the finishing stage. No differences were observed in the apparent retentions of Se for any Se sources and levels for broilers. The physicochemical characteristics of the meat were influenced by the sources of both for broilers and pigs, and the biocomplexed sources presented better results than the inorganic source. Se muscular deposition was also influenced by the dietary source of Se, by the inclusion level and the age of supplementation of the birds, and the biocomplexed sources provided greater deposition of muscular Se for birds and for pigs. For birds, a linear increase in the deposition of muscle was observed according to the dietary levels of SM, however, for pigs, a quadratic behavior was verified in the muscular deposition. It has also been found that supplementing SM at the level of 0.5 ppm only in the last week before the slaughter of broiler, a similar deposition can be obtained by supplementing SM at the level of 0.3 ppm from 1 to 42 days. The biocomplexed sources of Se were more bioavailable than sodium selenite, providing greater muscular deposition and improvement in meat quality characteristics for both chickens and pigs.