Organ growth and fermentation profiles of broilers differing in body growth rate

The modern broiler chicken is the product of nearly six decades of intensive selection for improved growth rate, feed efficiency, and reduced time to reach market weight. Despite these pressures, modern broiler populations still exhibit rates and efficiencies of growth that vary widely. Economically it is advantageous for companies to understand why some broilers are outperforming others within the same population. Because of this, an experiment was conducted to elucidate relationships between feed efficiency and development, structure, and function of the intestinal tract. Ross 308 broilers were allotted by bodyweight (BW) at arrival and reared for 11 days on a corn-soybean meal diet and then separated by growth percentiles to create two treatment groups. The Slow treatment group consisted of chicks that were at the 10th percentile for BW gain, and the Fast treatment group was comprised of chicks selected from the 90th percentile. On days 11 and 25, 10 chicks from each treatment group were weighed and euthanized to permit the collection of organ weights, lengths, and tissue samples for quantifying intestinal morphology, along with luminal contents for measuring end-products of microbial fermentation. Fast chicks were heavier (P < 0.001) than the slow group on day 11 and maintained that difference through study completion. Additionally, the BW gain through the grower period (d 11-25) was higher (P < 0.001) in the Fast group alongside feed intake (P = 0.002). However, feed conversion ratio (FCR) did not significantly differ across the treatments. Little difference was observed in organ lengths at d 11 and 25 but relative weights in metabolically active organs like the gizzard, proventriculus, pancreas, and liver among others were higher (P < 0.05) in the Slow group. Measurement of gut histomorphology did not show any notable changes in villi height, crypt depth, or their ratio for either time-point, though the ratio for the Fast group on day 25 tended to be higher (P = 0.054). Additionally, differences in volatile fatty acids were observed, specifically acetate concentrations were 10.2% higher (P < 0.001) in the ileum of the Slow group compared with the Fast group on d 25. Overall, the findings of this research suggest that total BW gain may be driven by the development of metabolically active organs, as supported by lower BW gain in Slow birds that expressed larger relative organ weights compared with Fast birds. Broilers that prioritize offal organs over muscle development are not as efficient to the meat industry, in selecting for birds that maximize economically important tissues both the producer and consumer benefit.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Animal Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Gorenz, Bradley E.

Contributors dc:contributor

• Dilger, Ryan N.
• Mackie, Roderick I.
• Parsons, Carl M.

• Broilers
• Growth
• Development
• Chickens
• Organs

Statement dc:rights

• Copyright 2023 Bradley Gorenz

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/120231

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F120231