Exigências nutricionais, validação de equações para a estimação da composição do corpo vazio e uso da creatinina para estimar a proporção de tecido muscular em bovinos Nelore

• Ano de defesa: 2011
• Autor(a) principal: Silva, Luiz Fernando Costa e
• Orientador(a): Valadares Filho, Sebastião de Campos
• Banca de defesa: Chizzotti, Mario Luiz , Valadares, Rilene Ferreira Diniz
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Creatinina; Bovinos; Exigências
• Palavras-chave em Inglês: Creatinine; Bulls; Requirements
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL
• Link de acesso: http://locus.ufv.br/handle/123456789/5716

The study was conducted by four experiments with the aim of to evaluate the intake, digestibility, performance, microbial efficiency, evaluate the equation for predicting dry matter intake obtained by BR CORTE (2010) and estimate the maturity weight of Nellore bulls; estimate the nutritional requirements of protein and energy of Nellore bulls; evaluate the equation for predicting body composition obtained by Marcondes et al. (2011), pelo BR CORTE (2006 and 2010), described by Valadares Filho et al. (2006) and Marcondes et al. (2010), respectively, and by Hankins & Howe (1946), by the 9-10-11ª rib cut; and estimate the muscle and crude protein content in carcass and crude protein content in empty body by the urinary creatinine excretion and, inversely, estimate the urinary creatinine excretion by shrunk body weight (SBW). In the experiment I, thirty seven Nellore bulls with initial body weight of 259±24.9 kg and 14±1 month old. Five animals were slaughter in the before of beginning the experiment (reference group), four in maintenance and the twenty eight remaining fed ad libitum and divided in four group which each group was slaughter each 42 days. The diet was composed for 0.55 of corn silage and 0.45 of concentrate in the dry matter. When expressed in kg/day, difference was observed (P<0.05) only to intake of ether extract and neutral detergent fiber in function of feedlot periods. Difference was observed (P<0.05) only to the digestibility coefficient of ether extract. Although there were differences in relation to consumption of nutrients, this difference did not affect the digestibility of the same. The equation proposed by BR CORTE (2010) estimates correctly the dry matter intake of Nellore bulls. The ADG was not influenced (P<0.05) in function of feedlot periods. Differences was not observed (P>0.05) to the microbial efficiency which the average value obtained was 141.50 g of CPmic/kg of TDN. The muscle and bone tissue and the crude protein, mineral matter and water contents in empty body weight increases when the animal grows, but in a smaller proportion. The adipose tissue and the ether extract present in empty body increases the deposition rate when the animal achieves the maturity weight. The maturity weight can be estimated considering the moment that the animal achieves 22% of the ether extract in EBW. The Nellore cattle achieve the maturity weight with 455.6 kg of EBW or 497.3 kg of BW. Therefore, this study concluded that the feedlot periods do not influence the intake of dry matter and the some nutrients as well as to the average dairy gain and the microbial efficiency. The Nellore bulls achieve the maturity weight when the bulls have 455.6 kg of EBW or 497.3 kg of BW. In the experiment II, the same animals were using in the experiment I where this animals were slaughter and the left half carcass was completely dissected to evaluate the body composition. The chemical body compositions were obtained by tissue chemical analysis. The net (NEm) and metabolizable (MEm) energy requirements to maintenance of Nellore bulls are 76.5 e 113.84 kcal/EBW0.75/day, respectively. The efficiencies of energy deposition in the form of protein and fat are 0.18 and 0.71, respectively. The obtained equations to retained energy (RE) and retained protein (RP) were: RE (Mcal/day) = 0.0555 × EBW0.75 × EBG1.095 and RP (g/day) = 263.37 × EBG 23.21 × RE. The efficiencies of metabolizable energy utilization to maintenance (km) and to growth (kg) were 0.67 and 0.33, respectively. This study concluded that the NEm and MEm to Nellore bulls are 76.5 e 113.84 kcal/EBW0.75/day and the RE and RP can be obtained by the equations: RE (Mcal/day) = 0.0555 × EBW0.75 × EBG1.095 and RP (g/day) = 263.37 × EBG 23.21 × RE. In the experiment III, the predicted values of the equations by Marcondes et al. (2011), BR CORTE (Marcondes et al., 2010 and Valadares Filho et al., 2006) and Hankins & Howe (1946), by the 9-10-11th rib cut section, were compared with the observed values for this study to the carcass physical and carcass and empty body chemical composition besides the non-carcass components chemical composition. The equations by Marcondes et al. (2011) estimate the carcass physical composition while the muscle tissue was underestimated and the fat tissue was overestimated by Hankins & Howe (1946). The equations by BR CORTE (2010) estimate correctly the carcass and empty body chemical composition while the carcass water was underestimated by Hankins & Howe (1946). The equations by BR CORTE (2006) do not estimate the carcass and empty body chemical composition. Only some non-carcass components were estimated exactly by BR CORTE (2010). This study concluded the proposed equations by Marcondes et al (2011) estimate the carcass physical composition while the equations by BR CORTE (2010) estimate the carcass and empty body chemical composition. The equations by Hankins & Howe (1946) were not recommended to the utilization for estimate carcass physical and chemical compositions of Nellore bulls. Regarding non-carcass components, only some constituents are estimated by equations of BR CORTE (2010). In the experiment IV, the data of muscle tissue, carcass and empty body crude protein content and body weight were collected of six studies to estimate the muscle tissue content and carcass and empty body crude protein content by the urinary creatinine excretion (UCE) and, inversely, the UCE by the SBW. The carcass muscle content (Mcarc) of Nellore (bulls and heifers) can be estimated by: Mcarc (kg) = 14.4040 × UCE (g/day). The carcass (CPcarc) and empty body weight crude protein (CPEBW) can be estimated by CPcarc = 3.8508 × UCE (g/day) and CPEBW = 5.8636 × UCE (g/day). The UCE of Nellore can be obtained by: UCE (g/day) = 0.0345 × SBW0.9491. Therefore, this study concluded that to each one gram of urinary creatinine excretion, it has 14.40 kg of muscle tissue, 3.85 kg of CPcarc and 5.86 kg of CPEBW present in heifers and bulls Nellore. The urinary creatinine excretion in Zebu can be estimated by the shrunk body weight by: UCE (g/day) = 0.0345 × SBW0.9491.