Evaluating the effect of yeast cell wall supplementation on ideal threonine to lysine ratios in broilers as measured by performance, intestinal mucin secretion, morphology, and goblet cell number

Abstract

SUMMARY The objective of this study was to investigate whether or not a prebiotic yeast cell wall (YCW), previously shown to improve performance in challenge studies, affects threonine requirements of broilers. Gain, F/G, intestinal morphology, mucin secretion, and goblet cell (GC) number per villi were measured. A total of 240 1-d-old Ross 308 broiler chickens were distributed in 2 Petersime battery brooder units (48 pens; 5 birds per pen). Birds were fed for a 21-d trial with different threonine to lysine ratios (0.65, 0.70, and 0.75) with and without YCW at 250 ppm. A basal diet with 22% protein and 2,980 Kcal/kg ME was used for the dietary treatments. The calculated lysine concentration was 1.35%, while threonine was 0.88%, 0.95%, and 1.02%, respectively. Birds and feed were weighed by pen, and the weights recorded at days 0, 7, 14, and 21 of the experiment for general performance data. At day 21, samples from excreta and small intestine (jejunum and ileum) were collected. YCW did not show any significant effect with respect to the variables evaluated in this non-challenge study. There was no significant effect for threonine to lysine ratios for all performance variables that had been measured throughout the study. With respect to intestinal morphology, there were significant increases in main effects for the threonine to lysine ratio 0.75 compared with 0.65 in mucin secretion, GC, and jejunum VW, while the jejunum VH significantly increased compared with threonine to lysine ratio 0.70.