Effects of dietary fibre source and enzyme supplementation on faecal apparent digestibility, short chain fatty acid production and activity of bacterial enzymes in the gut of piglets

The effects of fibre source, either wheat bran (WB) or maize cobs (MC), and dietary exogenous enzymes (ES) on performance and digestive parameters of weaned piglets were studied in 24 Duroc×Landrace male piglets, weaned at 21 days of age. There were four treatments arranged factorially, with two sources of fibre (WB or MC) and two concentrations of ES (0 or 0.15 g/kg) that contained 800 U/kg of endo-1,4- -cellulase, 1800 U/kg of endo-1,3(4)- -d-glucanase and 2600 U/kg of endo-1,4- -xylanase. The digestibility of the neutral detergent fibre was higher (P<0.001) in diets containing WB and the digestibility of the acid detergent fibre increased with ES. Small intestine digesta contents (g/kg live weight) at slaughter were higher (P<0.01) in pigs fed MC than in pigs fed WB. Fibre source did not affect the amounts (mmol/l) of short chain fatty acids (SCFA) in the small intestine. However, replacement of WB by MC increased acetic acid and decreased butyric acid concentrations (P<0.05) in the caecum. In addition, pigs fed diets with MC as the major fibre source had lower (P<0.05) concentration of butyric acid in the colon than pigs fed diets with WB. Enzyme supplementation affected molar proportions of SCFA formed in the small intestine and tended to increase acetic acid, propionic acid and total SCFA concentrations in the colon of piglets fed WB (P<0.10). The xylanolytic and cellulolytic activities in the caecum and colon were higher (P<0.05) for piglets fed WB than for piglets fed MC. In conclusion, ES increased the digestibility of acid detergent fibre and neutral detergent fibre and the replacement of WB by MC reduced neutral detergent fibre and acid detergent fibre digestibility, caecal butyric acid production and hindgut activity of bacterial enzymes

Eficiência do nitrogênio, produtividade e composição do capim-andropogon sob irrigação e adubação

The effects of different irrigation levels and nitrogen rates on the dry matter (DM) yield, nitrogen use efficiency and bromatological composition of andropogon grass (Andropogon gayanus 'Planaltina') were evaluated. The experiment consisted in a completely randomized block design, with three repetitions, with 2x4 factorial arran- gement, being two irrigation levels (50% and 80% of evaporation of the Class A evaporation: ECA) and four N levels (200, 400, 600 and 800 kg/ha/ year) applied as urea, divided in function of the cuts number (16.7, 33.3, 50.0 e 66.7 kg/ha/month). The water supply applied presented similar behaviors in relationship to the total dry matter productivity, leaves and stems. The water supply of 80% ECA provided the smaller leaf/stem ratio. The nitrogen fertilization influenced positively the total dry matter productivity, leaves and stems productivities however, the leaf/stem ratio and nitrogen use efficiency decreased. The crude protein contents of leaves and culms were not affected by water supply, but were increased by N fertilization. The NDF and ADF contents were negatively influenced by the largest water supply. The 50% of ECA irrigation presented the best results, associated to the application of 800 kg of N/ha/year, considering the productivity, broma- tological composition and the possibility of economy of water, with consequent reduction in the costs of herbage production.Foram avaliados os efeitos de diferentes lâminas de irrigação e doses de nitrogênio sobre a produção, eficiência do uso do nitrogênio e composição bromatológica do capim-andropogon (Andropogon gayanus 'Planaltina'). O delineamento experimental foi em blocos casualizados, num esquema fatorial 2x4, com três repetições; sendo dois níveis de irrigação (50% e 80% da evaporação do Tanque Classe A, ECA) e quatro níveis de N (200, 400, 600 e 800 kg/ha/ano) aplicados na forma de uréia e fracionados em função do núme- ro de cortes (16,7; 33,3; 50,0 e 66,7 kg de N/ha/ mês). As lâminas de irrigação aplicadas apresentaram comportamentos semelhantes em relação à produtividade de matéria seca total, de folhas e colmos. A lâmina de 80% de ECA proporcionou menor relação folha/colmo. A adubação nitrogenada influenciou positivamente a produtividade de matéria seca total, de folhas e colmos, no entanto, diminuiu a relação folha/colmo e a eficiência de utilização do nitrogênio. Os teores de proteína bruta das folhas e colmos não foram influenciados pelas lâminas de irrigação aplica- das, mas aumentou linearmente com a adubação nitrogenada. Os teores de FDN e FDA apre- sentaram influência negativa da maior lâmina de irrigação. A irrigação de 50% de ECA, associada à aplicação de 800 kg de N/ha/ano, apresentou os melhores resultados, considerando-se a pro- dutividade, relação folha/colmo, composição bromatológica e a possibilidade de economia de água, com conseqüente redução nos custos de produção da forragem