Effect of Yeast Cell Wall Supplementation on Ideal Threonine to Lysine Ratios in Broilers as Measured by Performance, Intestinal Morphology, Ileal Digestibility and Mucin Secretion
Abstract
This research was conducted to evaluate the effect of yeast cell wall (YCW) supplementation on different ideal threonine to lysine ratios as measured by performance, intestinal morphology, ileal digestibility, mucin secretion and goblet cell numbers.
In the first study, the objective was to evaluate whether or not the use of prebiotic YCW affects threonine requirements in broilers. Two hundred and forty 1-day-old Ross 308 broiler chickens were distributed in 48 pens; 5 bird per pen for a 21 day study. Different threonine to lysine ratios were used (0.60, 0.65, and 0.70) with 1.34% lysine with and without YCW at 250 ppm. The dietary treatments were fed to the birds to evaluate growth performance and intestinal morphology. The threonine to lysine ratio of 0.70 resulted in significant improvement of performance variables with increased ileum villi height (VH) and jejunum villi width (VW) compared with the other threonine to lysine ratios. Adding YCW did not necessarily require additional threonine for maximum starter broiler performance.
In the second study, the objective was the same as the first study with slightly higher threonine to lysine ratios (0.65, 0.70, and 0.75) with 1.35% total lysine with and without YCW at 250 ppm. The variables that were measured included performance, mucin secretion, goblet cell numbers and intestinal morphology for jejunum and ileum at day 21 of the study. There was no effect for YCW on all the variables that were measured. There was a significant main effect for the threonine to lysine ratio 0.75 compared with 0.65, with increasing mucin secretion, goblet cell number, and decreasing jejunum VW, while the jejunum VH significantly increased compared with the 0.70 threonine to lysine ratio.
In the third study, newly hatched broiler chicks (48 pens, 12 replicates per treatment) were distributed among four dietary treatments to investigate the effect of prebiotic YCW in broilers fed diets with a threonine to lysine ratio of 0.60 using a Clostridium perfringens challenge model. The effects of the dietary treatments were determined on performance, ileal digestibility, jejunum and ileum intestinal morphology and the severity of the necrotic enteritis lesions. Results indicated that there was a significant main effect for YCW on performance represented by higher body weight (BW) and productivity index (PI) with improvement in phase feed conversion ratio (PFCR) at days 10 and 16 of the study before the Clostridium perfringens challenge. At day 21, the non-challenge treatment with YCW at 250 ppm was significantly different from other treatments with higher PI. There was a significant main effect for the severity of the lesion scoring in the non-challenged with 0.62 compared with 1.05 for the challenged. The intestinal morphology results and the ileal digestibility showed no differences between treatments. Adding YCW at 250 ppm did not change the threonine requirements for starter broilers, and YCW did not show any significant effect on jejunum and ileum intestinal morphology and ileal digestibility. In conclusion, adding a YCW prebiotic does not require feeding additional threonine to increase the ideal threonine to lysine ratio in broiler diets.
Citation
Abdaljaleel, Raghad Ali (2018). Effect of Yeast Cell Wall Supplementation on Ideal Threonine to Lysine Ratios in Broilers as Measured by Performance, Intestinal Morphology, Ileal Digestibility and Mucin Secretion. Doctoral dissertation, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /173416.