Determination of apparent digestibility coefficients in 6-, 12- and 18-week-old ostriches

The fate of insoluble arabinoxylan and lignin in broilers: Influence of cereal type and dietary enzymes

Insoluble fiber degradation by supplemented enzymes was previously shown to improve fermentation in poultry, and has been further postulated to disrupt the cereal cell wall matrix, thus improving nutrient digestion. Here, we characterized insoluble feed-derived polysaccharides and lignin in digesta from broilers fed wheat-soybean and maize-soybean diets without or with xylanase/glucanase supplementation. Enzyme supplementation in wheat-soybean diet increased the yield of water-extractable arabinoxylan (AX) in the ileum. Still, most AX (> 73 %) remained insoluble across wheat-soybean and maize-soybean diets. Analysis of so-far largely ignored lignin demonstrated that a lignin-rich fiber fraction accumulated in the gizzard, while both insoluble AX and lignin reaching the ileum appeared to be excreted unfermented. More than 20 % of water-insoluble AX was extracted by 1 M NaOH and 11-20 % was sequentially extracted by 4 M NaOH, alongside other hemicelluloses, from ileal digesta and excreta across all diets. These findings showed that enzyme-supplementation did not impact AX extractability by alkali, under the current experimental conditions. It is, therefore, suggested that the degradation of insoluble AX by dietary xylanase in vivo mainly results in arabinoxylo-oligosaccharide release, which is not accompanied by a more loose cell wall architecture.

Prediction of digestible energy and gross energy digestibility of feeds and diets in ostriches

1. The aim of this study was to assess regression equations able to predict the digestible energy (DE) and gross energy digestibility (GEd) of feed ingredients and diets for ostriches. 2. Results of chemical-nutritional characteristics from 17 ingredients (two varieties of maize, two barleys, oat, triticale, wheat bran, soybean meal, sunflower meal, beet pulp, maize silage, alfalfa hay, 4 alfalfa meals and lupin) and 12 experimental diets were used in a stepwise procedure. 3. Acid detergent lignin (ADL) was the first independent variable included in the model to predict the DE of all the samples (R(2) = 0.65 and Residual Standard Deviation (RSD) 1.02). When the concentration of ash, acid detergent fibre (ADF) and crude fibre were included in the model, the R(2) value of the regression equation increased (from 0.65 to 0.85) and RSD decreased (from 1.02 to 0.48). 4. The ADL concentration was also the first independent variable chosen by the stepwise regression analysis for the estimation of GEd from chemical-nutritional characteristics of feeds, explaining 57% of the total GEd variation. The concentrations of crude protein and ADF included at the second and third steps in the model increased the R(2) (up to 0.70 and 0.73, respectively) and decreased the RSD values (from 0.29 to 0.21 and 0.20, respectively). When other variables as crude fibre, ash and gross energy were included in the model, the coefficient of determination and the RSD strongly improved (0.85 and 0.12, respectively).

Methods to determine metabolizable energy and digestibility of feed ingredients in the domestic pigeon (Columba livia domestica)

The influence of length of excreta collection period (1, 3, 6, 10, 14 d) and prefeeding protocol (7 d either individual feeding in collection cages or group feeding in housing cages) on AMEn, nitrogen retention (NR), and apparent DM, organic matter and ether extract digestibility of corn and peas were evaluated in domestic pigeons (Columba livia domestica). In addition, the use of internal markers [acid-insoluble ash (AIA) and acid detergent lignin (ADL)] to determine AMEn, NR, and apparent digestibility was compared with the method of measuring total feed input and excreta output. A quadratic (y = a + bx + cx2) trend in the CV for AMEn, NR, and apparent digestibility coefficients found over collection periods with corn presented evidence that excreta collection for a period of 3 d will produce a CV of 5% less than the minimum CV. Although no trend could be detected in CV for peas, a 3-d excreta collection period resulted in relatively low variation. Both AIA and ADL, when used as internal markers, resulted in AMEn, NR, and digestibility values below (P < 0.05) those obtained with total collection with corn. However, values between markers were comparable (P > 0.05) for all components evaluated. The ADL was unsuccessful as marker with peas. Group prefeeding of pigeons in housing cages resulted in lower feed intake, excreta output, NR, and apparent digestibility than when birds were adapted individually to collection cages. This study presents evidence that the method of measuring total feed intake and excreta output for a period of 3 d, with individual adaptation of birds to collection cages, resulted in the most reliable values for AMEn, NR, and apparent digestibility of DM, organic matter and ether extract of feed ingredients in pigeons.