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 AME(n), 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 (ATA) and acid detergent lignin (ADL)] to determine AME(n), NR, and apparent digestibility was compared with the method of measuring total feed input and excreta output. A quadratic (y = a + bx + cx(2)) trend in the CV for AME(n), 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 AME(n), 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.