SOME FACTORS AFFECTING THE TRUE METABOLIZABLE ENERGY VALUES OF SOYBEAN MEAL AND RAPESEED MEALS

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Abstract
The effects of the age of bird and level of feed input on the true metabolizable energy (TME) values of soybean meal and rapeseed meals (RSM), Tower and Candle, were investigated using adult Single Combed White Leghorn (SCWL) cockerels. Feed was administered to each bird in pellet form. In the 10-mo-old birds the input level was 28 g while levels of 15, 30, 45 and 60 g were employed with the 2-yr-old birds. The effect of rapeseed and soybean gums on the TME and apparent metabolizable energy (AME) values of their meals as well as the effect of processing method on the TME of RSM were also determined. The TME values obtained with 10-mo-old birds were not significantly different from those determined with the same birds at the age of 2 yr. No regurgitation of feed was encountered at any of the four feed input levels. Although there were some differences in the TME values at the different feed input levels of the feedingstuffs being tested, the value was significantly (P < 0.05) affected only in the case of Candle RSM. The TME values of both Tower and Candle RSM were particularly high at the 60-g input level, most likely due to incomplete excreta output. Soybean and rapeseed gums did not affect the TME and AME values of the meals, possibly due to the low level added (1.5%). Solvent-extracted Tower RSM was significantly higher in TME than pre-press solvent Tower meal; this difference may have been due in part to the difference in lipid content of the two meals.