Abstract
BackgroundThe provision of feed is a major cost in beef production. Therefore, the improvement of feed efficiency is warranted. The direct assessment of feed efficiency has limitations and alternatives are needed. Small intestine micro-architecture is associated with function and may be related to feed efficiency. The objective was to verify the potential histomorphological differences in the small intestine of animals with divergent feed efficiency.MethodsFrom a population of 45 feedlot steers, 12 were selected with low-RFI (superior feed efficiency) and 12 with high-RFI (inferior feed efficiency) at the end of the finishing period. The animals were processed at 13.79 ± 1.21 months of age. Within 1.5 h of slaughter the gastrointestinal tract was collected and segments from duodenum and ileum were harvested. Tissue fragments were processed, sectioned and stained with hematoxylin and eosin. Photomicroscopy images were taken under 1000x magnification. For each animal 100 intestinal crypts were imaged, in a cross section view, from each of the two intestinal segments. Images were analyzed using the software ImageJ®. The measurements taken were: crypt area, crypt perimeter, crypt lumen area, nuclei number and the cell size was indirectly calculated. Data were analyzed using general linear model and correlation procedures of SAS®.ResultsEfficient beef steers (low-RFI) have a greater cellularity (indicated by nuclei number) in the small intestinal crypts, both in duodenum and ileum, than less efficient beef steers (high-RFI) (P < 0.05). The mean values for the nuclei number of the low-RFI and high-RFI groups were 33.16 and 30.30 in the duodenum and 37.21 and 33.65 in the ileum, respectively. The average size of the cells did not differ between feed efficiency groups in both segments (P ≥ 0.10). A trend was observed (P ≤ 0.10) for greater crypt area and crypt perimeter in the ileum for cattle with improved feed efficiency.ConclusionImproved feed efficiency is associated with greater cellularity and no differences on average cell size in the crypts of the small intestine in the bovine. These observations are likely to lead to an increase in the energy demand by the small intestine regardless of the more desirable feed efficiency.
Highlights
The provision of feed is a major cost in beef production
It is interesting to note that the different measurements obtained in both duodenum and ileum presented similar variability, as indicated by the coefficient of variation
Perimeter and area of the crypt (CP; crypt area (CA)) in the duodenum showed a tendency (P ≤ 0.10) to be larger for the more efficient animals, which was not seen in the ileum crypts (P ≥ 0.10)
Summary
The provision of feed is a major cost in beef production. the improvement of feed efficiency is warranted. Small intestine micro-architecture is associated with function and may be related to feed efficiency. The objective was to verify the potential histomorphological differences in the small intestine of animals with divergent feed efficiency. One of the major costs in beef production is the provision of feed. The direct assessment of feed efficiency in cattle is one of the ways to reduce those costs of production. Residual feed intake (RFI) is a feed efficiency measure, first defined in beef cattle by [13] and largely used to study the biology of feed efficiency and to verify the effectiveness of indirect indicators of feed efficiency [14,15,16,17,18]. Differences in RFI reflect variation among animals’ background energy requirements, which are largely influenced by the visceral organs [3,19]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call