Influência do processamento do grão de milho na digestibilidade de rações e no desempenho de bezerros

Abstract

RESUMO -Objetivou-se avaliar a influência do processamento grão de milho (inteiro, tratado com uréia ou moído na forma de quirera) sobre a digestibilidade de rações e no desempenho de bezerros desmamados precocemente e mantidos em regime de confinamento. A dieta foi formulada com silagem de sorgo como volumoso, em uma relação volumoso:concentrado de 40:60, na matéria seca. A digestibilidade in vivo da matéria seca (MS), matéria orgânica, proteína bruta, extrato etéreo, fibra em detergente neutro, fibra em detergente ácido, celulose, energia bruta e amido, o pH das fezes e o consumo de MS foram efetuados em um ensaio com seis bezerros, castrados, com sete meses de idade. A influência das dietas no desempenho dos animais foi avaliada em ensaio com 15 bezerros não-castrados e idades semelhantes aos do ensaio de digestibilidade, com peso vivo inicial médio de 159 kg. O processamento do grão de milho não influenciou as variáveis analisadas, exceto o pH das fezes, que apresentou valor mais baixo nos animais que receberam dieta contendo grão de milho moído. Palavras-chave: pH das fezes, uréia Effects of corn grain processing on digestibility of diets and performance of calvesABSTRACT -The effect of corn grain processing (whole, treated with urea, or crushed forms) on the digestibility of diets and performance in early weaned calves kept in feedlot was evaluated. The diet was formulated with silage sorghum as forage in 40:60 forage to concentrate ratio (%DM). Digestibility of dry matter (DM), organic matter, crude protein, ether extract, neutral detergent fiber, acid detergent fiber, cellulose, gross energy and starch, fecal pH and DM intake were evaluated in an assay using six 7-mo castrated calves. Treatment effect on animal performance was evaluated in an assay using 15 non-castrated calves with ages similar to those of the digestibility assay, with initial 159 kg BW. The corn grain processing did not affect the evaluated characteristics, except for fecal pH, that was lower in the animals fed diet with crushed corn grain.Key Words: fecal pH, urea IntroduçãoO desempenho animal está diretamente relacionado ao consumo de nutrientes, que, sua vez, depende da natureza física e química dos alimentos e da digestibilidade da dieta (Waldo, 1973;Ferrell, 1993).Altos níveis de produção animal geralmente estão associados a aumento na proporção de alimentos ricos em carboidratos solúveis. Esse aumento na proporção de carboidratos solúveis pode ocasionar diminuição do pH ruminal, redução da digestibilidade da fibra (Owens & Goetsch, 1993;Van Soest, 1994) e diminuição no consumo (Bengochea et al., 2005), logo, a melhoria no desempenho não é proporcional ao aumento do conteúdo de energia da dieta.Existem diversos tipos de processamento -como os tratamentos mecânicos (descascamento, prensagem, moagem e laminação) e térmicos (calor seco: tostagem, micronização e estalação; e calor úmido: cozimento, dilatação, floculação e peletização) -, todavia, nem todos são acessíveis econô-mica e tecnologicamente ao produtor brasileiro.O milho é a...

<b>Nitrogen sources associated with different physical forms of corn grain in the diet for steers in feedlot

“…Considering the physical form of the corn grain included in the concentrate fraction, there was no difference (p > 0.05) in the intake values. A similar result was reported by Vargas Junior et al (2008) evaluating whole or ground grain in the feeding of feedlot calves. It was expected that there would be interaction between the factors studied by the presence of non-protein nitrogen, combined with ground corn, due to the possible greater synchronism in the degradation of carbohydrates and nitrogen compounds, but this hypothesis was not confirmed.…”

“…From the point of view of practicality and operational processes, the result obtained for the physical form of the grain is extremely relevant, since it demonstrates that it is not necessary to grind the grain before supplying it to the finishing cattle. In their studies (Vargas Junior et al (2008)) observed an electricity consumption of 6.3 kWh per ton of ground corn compared to an energy consumption of zero when supplying whole grains, a relevance aspect in this type of study.…”

“…These diets consisted of different combinations of nitrogen source and physical form of the corn grain, in the concentrate fraction, being: soybean meal associated with whole or ground corn, conventional urea associated with whole or ground corn and protected urea associated with whole or ground corn. The procedure to obtain the physical form of ground corn was grinding in a hammer mill with a 2 mm sieve, as used in similar work by Vargas Junior et al (2008).…”

“…Processing such as grinding is used to increase the surface area of the grains to facilitate digestive processes. Vargas Junior, Sanchez, Wechsler, Bianchini, and Oliveira (2008) provided whole or ground corn for calves without changes in intake and performance. Benedeti et al (2014) found decreasing dry matter intake when replacing soybean meal by protected urea and attributed it to the high digestibility of the finely ground corn used in the diet, which would not have been accompanied by the assimilation of nitrogen in the rumen, which was released gradually.…”

Influence of corn processing provided in the diet on the ruminal dynamics of dairy steer

“…According to Vargas Junior et al (2008), the treatment of corn grains with urea is of interest because, in addition to allowing the storage of the cereal on the farm under high humidity conditions and free from pests, it also acts in the pre-processing of the cereal, inasmuch as urea, because of being diluted in water and mixed with corn in a sealed environment, causes microfissures in the grain lining layers, thus facilitating the access to bacteria and the degradation of starch granules. However, Alcade & Andrade (1997) underlined that, despite being a common practice, the processing of corn grains often does not have the expected efficacy.…”