Determination of the true metabolizable energy (TMEN) by roosters of feedstuffs made from seal by-products

Abstract

TMEN values for various seal by-product feedstuffs were determined using roosters. Four samples of seal meal [seal meal 1991, seal meal 1992, seal meal 1994 (juveniles), seal meal 1994 (mixed ages)] and three samples of seal meat (oven-dried at 50 °C, oven-dried at 120 °C, and freeze-dried) were given to 16 roosters (30 g: precision fed) housed in individual wire cages. Total collection of excreta from a 48-h period was used to provide samples for analysis of gross energy, nitrogen, and dry matter content. TMEN results indicate variability in quality of the meals, associated with the different raw materials used to produce the seal meals as well as year of production. The TMEN values for the seal meals ranged from 3896 kcal kg−1 to 4621 kcal kg−1 with an average value of 4283 kcal kg−1. The crude protein content of the seal meals ranged from 64.2 to 67.6%, the crude fat content from 12.7 to 14.7%, the calcium content from 5.38 to 8.98% and the total phosphorus content from 3.16 to 4.79%. Oven-drying the seal meat at 120 °C significantly reduced TMEN (2643 kcal kg–1). The TMEN values for the freeze-dried and the low temperature oven-dried (50 °C) seal meat were not significantly different (4008 kcal kg–1 and 4013 kcal kg–1, respectively). Key words: True metabolizable energy, seal by-products, roosters, seal meal, seal meat, TMEN