Desempenho, características da carcaça e qualidade da carne de novilhas de diferentes genótipos terminadas no sistema pasto/suplemento

• Autor(a) principal: Estrada, Mauricio Miguel
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5831
• topic: Novilha; Novilha - Variedades; Nutrição animal; Novilha - Carcaça; Novilha - Carne - Qualidade; Heifer; Heifer - Variety; Animal nutrition; Heifer - Housing; Heifer - Meat - Quality; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

The purpose of this study was to determine the feasibility productive, carcass characteristics and meat quality of heifers finished in grazing with supplementation and slaughtered at three different times. The first part comprise a literature review of aspects of beef production in Brazil, as well the importance of the production of meat with females and their implications on performance, carcass quality and meat. The second part aimed evaluate the performance, carcass characteristics and meat quality of three different genotypes heifers finished on pasture / supplement system and slaughtered in three times of supplementation. To achieve this goal, were finished on pasture with supplementation of 0.7% of body weight, heifers from three genetic groups: Angus X Nelore (ANE); Mixed Dairy (MLT) and Nelore (NEL), being 36 heifers ANE, 32 MLT e 30 NEL, with initial body weight of 267+23; 305+31; and 320+19 kg respectively. Heifers were grouped into seven homogeneous lots, slaughtered a batch of 18 heifers (6 of each genetic group) to start the experiment as slaughter reference that was used to calculate the empty body weight and carcass weight of the original animals that remained in the experiment. The slaughter was carried out in a commercial refrigerator. The remaining heifers were grouped into homogeneous lots with the same number of animals of each genetic group. These lots were placed in continuous grazing providing daily multiple supplementation to 0.7% of the lots weight. The animals were weighed every 28 days to adjust the amount of supplement offered and determine performance. Likewise, every 28 days was collecting pasture by means of the technique of double sampling to determine the availability and morphological composition of pasture in the paddocks, while pasture sampling was performed by simulated grazing to determine forage quality. Three experimental slaughter was carried out, the first 60 days of supplementation with 26 heifers slaughtered (10 ANE, 8 MLT and 8 NEL), the second at 90 days shooting 26 heifers (10 ANE, 8 MLT and 8 NEL) and the last to 132 days with 28 animals (10 ANE, 10 MLT and 8 NEL). In all slaughtering, the carcass components and not carcass were weighed to determine the empty body weight and carcass yield based on body weight and empty body weight. At the end of the slaughter line, the carcass was divided into two equal parts and placed in the cooling chamber. After 24 hours in the chamber, temperature and final pH were measured, and weighed again to determine the carcass weight of the cold carcass. The difference between hot carcass weight hot and carcass weight cold generate a chilling losses. The carcass right was separated into Front, Rear and Tip Needle cuts, these parts being weighed to determine the percentage based on the weight of the hot carcass. The same half carcass right, were obtained six steaks of 2.5 cm thick of Longissimus dorsi were divided into three groups of two steaks each, and placed to mature for 0, 7 and 14 days each group. These steaks were used to determine the quality of the meat, analysis of cooking losses, color, shear force, sarcomere length and myofibrillar fragmentation index being performed. On the other hand, the half carcass left was obtained section between the 9th and 11th ribs (section HH) to determine the chemical composition of the carcass and empty body by means of the equations proposed by BR-CORTE (2006). For the statistical analysis of the performance and carcass characteristics of an experimental randomized design with factorial arrangement 3x3, with the MIXED procedure of SAS, version 9.2 (SAS, 2008) using the initial weight as a covariate was used. As for the quality of the meat, the data were analyzed as repeated measures in function of ripening time (0, 7 and 14 days). Comparisons between means were performed using the test "t" at the level of 10% probability. The results showed a half production of the forage of 6.78 t/DM/ha, with 32% of green leaves and 26% of dead leaves, however the half of MSPD was 5.06 t/MSpd/ha. The pasture had 7.53% crude protein and 67.21% of FDNcp. Animal performance was interaction between time of supplementation and genetic group for the final weight, average daily gain, carcass weight hot, gain in carcass weight, carcass weight cold and percentage of the back cut. The ANE heifers had the highest final weight and average daily gain increased (P <0.1). The weight of hot and cold carcass, the ANE and NEL heifers showed higher value, differing from MLT that had lower (P <0.1). Carcass yield based on the body weight, the NEL heifers had 54% yield surpassing the ANE and MLT (P <0.1) with 52% yield. Likewise, the NEL heifers had the best performance gain of 68%, outperforming the ANE (61%) and MLT (54%), being different among the three genotypes (P <0.1). The initial and final temperature and pH did not differ between genetic groups. While the carcass cuts, the ANE heifers had the highest percentage of rear with 50.9% (P <0.1), surpassing the MLT and NEL with 50.3 and 50% respectively, no finding difference between them. Concludes that termination of heifers on pasture/supplement system is a viable option to increase the production of beef, and crossbred and Nelore females are available, in addition to presenting good carcass conformation and good yield rear; however, the shear force presented by the meat was high, which decreases the quality.