Avaliação de indicadores e de métodos de predição do valor energético da dieta em bovinos em crescimento

• Ano de defesa: 2010
• Autor(a) principal: Sampaio, Cláudia Batista
• Orientador(a): Detmann, Edenio
• Banca de defesa: Rennó, Luciana Navajas , Lopes, Fernando César Ferraz
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Zootecnia
• Departamento: Genética e Melhoramento de Animais Domésticos; Nutrição e Alimentação Animal; Pastagens e Forragicul
• País: BR
• Palavras-chave em Português: Dióxido de titânio; Fibra em detergente; Matéria seca indigestível; Óxido crômico
• Palavras-chave em Inglês: Titanium dioxide; Detergent fiber; Indigestible dry matter; Chromic oxide
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL::AVALIACAO DE ALIMENTOS PARA ANIMAIS
• Link de acesso: http://locus.ufv.br/handle/123456789/1866

The objective of this work was to estimate the total recovering, the long term and short term bias of the estimates of fecal excretion, and evaluate the fecal excretion profile using the external markers chromic oxide and titanium dioxide and the internal markers indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF); and, additionally, to estimate and evaluate the apparent digestible fractions of ether extract, crude protein and non-fibrous carbohydrates, the digestible fraction of neutral detergent fibre and the diet content of total digestible nutritents (TDN) using the chemical composition of feeds in growing cattle fed different diets. Fourteen F1 Red Angus x Nellore bulls, averaging 12 months and 287 kg, were used. The animals were fed with elephant grass silage, corn silage or signal grass hay and supplemented or not with 20% of concentrate. The experiment consisted of two 13-days experimental periods according to a 2 x 2 Latin square design with seven squares. The animals received 10 g/d of chromic oxide and titanium dioxide through esophageal sound. Total fecal collection was done and fecal grab samples were too obtained at 1h30, 3h00, 4h30 e 6h00, 7h30, 9h00, 10h30, 12h00, 13h30, 15h00, 16h30, 18h00, 19h30, 21h00, 22h30 and 24h00. The observed values of digestible fractions and TDN were obtained based on total collection of feces. There was no effect of forage, concentrate or their interaction on fecal recovering of external and internal markers. The average fecal recovering of chromic oxide and titanium dioxide were 99.50% and 101 95%, respectively. iDM, iNDF and iADF presented average fecal recovering of 99.02%, 98.87% and 102.07%, respectively. For all markers the fecal recovering was found to be 100% and all of them presented no long term bias. However, higher precision was observed for fecal excretion estimates obtained with internal markers. There were no effects of forages and concentrate levels on excretory cycle of markers. The fundamental periods of excretory cycle were 15.06 and 18.66 hours for chromic oxide and titanium dioxide, and 9.93, 9.29 and 10.55 hours for iDM, iNDF and iADF, respectively. The oscillation range was higher for external markers. Considering the characteristics of all markers, it is recommended fecal sampling designs with at least four collects, which can be distributed along day or along diurnal period. This recommendation looks for avoiding short term bias on fecal excretion estimates. Several sub-models applied to predict the different digestible fractions were evaluated and discussed. Estimates of diet content of TDN were produced from combination of sub-models applied to digestible fractions. The TDN content was better predicted using the sub-models of Detmann et al. (2010) and considering biological procedures to estimate the undegradable fraction of protein and the potentially digestible fraction of neutral detergent fiber.