Investigating changes in intestinal health parameters of laying hens, broilers, and broiler breeder hens
Date
2021-12
Authors
Wiersema, Maddison Lynn
Major Professor
Advisor
Koltes, Dawn
Schmitz-Esser, Stephan
Kerr, Brian
Committee Member
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Abstract
With the world’s growing population, it is important for poultry producers to continue to maximize production and efficiency while optimizing bird health. However, changes in housing requirements for laying hens due to the restricted use of antibiotics may alter intestinal health which may alter nutrient absorption and/or utilization. Therefore, the overall objectives of this thesis were to better understand poultry intestinal health by using an intestinal permeability assay to determine changes 1) due to housing type and stage of lay in laying hens, 2) in broiler breeder hens fed a direct-fed microbial (DFM) compared to control diets at the end of the productive cycle, and 3) across the production stage in broilers under a known stressor. To investigate these objectives, three projects were conducted. Project 1 (Chapter 2) further explored the effects of housing type on the intestinal health of laying hens during different time points in the hen production cycle. This study looked at differences in intestinal health in laying hens between enriched-colony (EC) and cage-free (CF) systems at peak-lay when egg production is high, and late-lay when production begins to decline. Hens from EC and CF systems were randomly chosen at 35 and 76 weeks of age and the FITC-D assay was used to determine intestinal permeability. A section of the ileum was collected for morphometric analysis. Minimal differences were observed in permeability and morphology between hens from both housing types; however, permeability increased at 76 weeks of age compared to 35 weeks of age (P < 0.01). Project 2 (Chapter 3) investigated the effects of a DFM on the intestinal health of broiler breeder hens. Hens in this study were fed 1 of 2 diets, a control diet (CON) or a diet containing a DFM. At the end of the production laying cycle (65 weeks of age), hens were orally gavaged with FITC-D, and blood samples were collected to measure intestinal permeability. Ileal segments were also collected for morphometric analysis. Hens fed the DFM diet had lower intestinal permeability (P = 0.04) and longer ileal villi compared to CON hens (P = 0.04). This suggests that the DFM improved intestinal health by decreasing non-selective passage of large particles and increasing absorptive surface area. The goal of Project 3 (Chapter 4) aimed to better understand how intestinal permeability of broilers changes during three different points in production while also assessing the impacts of feed restriction. Prior to oral gavage, half of the pens were feed restricted to induce intestinal permeability. Birds were orally gavaged with 1 of 4 treatments, FITC-D, lactulose, mannitol, and sucralose (LMS), a combination of FITC-D+LMS, or saline (control) at 14, 28, and 42 days of age. Feed-restricted birds had higher concentrations of serum FITC-D compared to birds that were not feed restricted (P < 0.01). Additionally, the highest concentrations of serum FITC-D were observed at day 14, indicating more intestinal permeability was seen in younger birds (P < 0.01), suggesting that immaturity of the gut and intestinal microbiome may contribute to increased intestinal permeability. Also, birds that received only FITC-D had the highest serum fluorescence, and serum fluorescence of birds that received the combination of FITC-D+LMS was not significantly different from those that received only LMS, which suggests that the combination of FITC-D+LMS resulted in some type of interference causing lower serum fluorescence levels.
In conclusion, these results can provide poultry producers and researchers with more information on the various factors that can influence intestinal permeability and presumably intestinal health in poultry, such as age, environment, and feed additives.
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