Light turkey syndrome: field study and inoculation trial.

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Light turkey syndrome: field study and inoculation trial.

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Light Turkey Syndrome (LTS) is characterized by lower than expected body weights of tom turkey flocks at market. Turkey producers have taken notice of LTS over the last five years. During brooding from two to three weeks of age is when weight gains begin to fall below what had previously been achieved. Speculation suggests that lighter poults are experiencing a different set of factors than the heavier weight poults in commercial flocks. The hypothesis for the field study was that poults from two weight groups (heavy and light) would have different histopathology scores for the intestine and immune tissue, different pathogens present and different xylose absorption. The objective of the inoculation trial was to determine if inoculated poults raised in research settings would exhibit similar attributes as the poults from the field study. In addition to the factors that had been looked at for the field study; weight gain, feed intake and feed conversion data were also determined. In both studies gut contents was collected for analysis by multiplex RT-PCR for astrovirus, rotavirus, reovirus and by culture methods for Salmonella, Campylobacter, E. coli and total plate counts for aerobic, anaerobic, lactobacilli and heterofermentative lactobacilli. Intestinal tissue was collected for scoring of heterophilic and lymphocytic infiltrates and select immune tissue was also scored. Xylose absorption was measured in plasma samples at zero and 60 minutes post gavage. Samples were collected at one, two and three weeks of age in the field study from four MN commercial flocks, two ND commercial flocks and two MN research flocks. Samples were collected at 14 days of age (seven days post inoculation) in the inoculation trial. For both studies more differences were seen between the different flocks than between the heavy and light weight groups. Salmonella and astrovirus were found in all flocks in the field study but reovirus was only found in two of the MN commercial flocks. In the field study histological differences were seen between weight groups with two flocks having an increased acute immune response in the light weight and heavy poults in all flocks showing increased lymphocytes in the intestinal tissue. For immune tissue lymphocytic necrosis and atrophy of the bursa were present in more light weight poults than heavy weight poults. Xylose absorption was increased in heavy weight poults in three of the commercial flocks when compared to light weight poults. In the inoculation trial control poults had the best weight gain and feed conversion with poults gavaged with the inoculums from commercial flocks having the worst. Heterophilic infiltrates were the highest in the control poults and lymphocytic infiltrates were highest in the light weight poults. Lymphocytic necrosis was found in more of the light weight poults. No differences were seen in xylose absorption between the heavy, light and control groups in the inoculation trial. Light turkey syndrome cannot be easily defined by a specific pathogen’s presence though a few different pathogens may likely play a role in the reduced weight gain seen in LTS poults. Histologically the gut and immune tissue indicate active immune responses that are decreasing the amount of nutrients available for growth of the bird. Nutrient absorption only appears to be negatively affected if the poult is actively showing signs of disease.


University of Minnesota M.S. thesis. July 2012. Major: Animal science. Advisor: Sally L. Noll. 1 computer file (PDF); xv, 177 pages, appendix p. 144-177.

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Calvert, Alamanda Joy. (2012). Light turkey syndrome: field study and inoculation trial.. Retrieved from the University Digital Conservancy,

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