Development of organs and intestinal mucosa leukocytes in four broiler lines that differ in susceptibility to malabsorption syndrome

Abstract

Growth retardation in young broiler chicks due to poor nutrient metabolism, commonly known as malabsorption syndrome (MAS), is a widespread problem caused by enteric infections with a combination of pathogens mainly viruses. Genetic lines of broiler chickens differ in susceptibility to the syndrome. A difference in growth retardation was observed among four broiler lines (BL) after oral inoculation at 1 d of age with intestinal homogenates obtained from MAS-affected birds. Two of the lines that are more susceptible to MAS had severe weight gain depression. To uncover the factors that play a role in the susceptibility to MAS, we analyzed the growth rate of the body and vital organs and the quantity of leukocytes in the peripheral blood and intestinal mucosa. The development of the intestine, liver, bursa of Fabricius, and spleen was similar among the BL. The resistant BL had higher numbers of peripheral blood leukocytes, especially lymphocytes, at 1 d of age. A significant difference was noted in the numbers of CD4+ T cells and CD8+ T cells in the intestinal villi. At the ages of 3 and 8 d, the susceptible BL had more CD8+ T cells in the villi, whereas the ratios of CD4+:CD8+ T cells were higher in the resistant BL. This difference in the number of T-cell subpopulations in the intestinal mucosa might be an important factor in the difference in susceptibility to the enteric infections associated with MAS.

Malabsorption syndrome in broilers

“…Interestingly, the heterophil infiltration was significantly more pronounced in the susceptible broilers than the resistant broilers. We have reported previous that at 1 day of age the chickens of line S have higher proportion of circulating heterophils in peripheral blood (Zekarias et al, 2002). This may be related to the greater heterophil infiltration into the intestinal mucosa in the MAS affected chickens of the MAS susceptible line compared to chickens of less MAS susceptible line.…”

“…The "resistant" broiler line at day 1 of age had higher percentages of peripheral blood leukocytes, especially lymphocytes. At 3 and 8 days the "resistant" line had less CD8 positive T cells in the small intestinal villi detected with immunohistochemistry, while the amount of CD4 positive cells was slightly higher in the "resistant" line as compared to the susceptible chickens ( Figure 2) (Zekarias et al, 2002). When MAS was inoculated in these broiler lines the number of CD8 positive cells in the small intestinal villi in the susceptible line was higher as compared to the "resistant" line (Songserm et al, 2002a).…”

“…Uni et al (1995) have shown that villus volume and enterocyte density are different in two broiler lines. Zekarias et al (2002) have investigated whether differences in intestinal morphology and organ development reflected susceptibility differences to MAS between broilers lines. Broiler lines were used that differ in MAS susceptibility to investigate whether an association between susceptibility and specific traits in the genetic background could be established.…”

“…Since chickens are susceptible to MAS immediately after hatching, at which time the gut mucosa and the systemic immune system are less well developed, differences in the development of the innate and adaptive immunity at early age could be a crucial factor in susceptibility differences to MAS (Bar Shira et al, 2003). Broilers that differ in MAS susceptibility differed significantly in their frequency of CD4/CD8 positive intestinal cells and amount of goblet cells in the intestine, both under challenge and nonchallenge conditions (Songserm et al, 2002a;Zekarias et al, 2002). The "resistant" broiler line at day 1 of age had higher percentages of peripheral blood leukocytes, especially lymphocytes.…”

Klinische, virologische und bakteriologische Untersuchungen zum Malabsorptionssyndrom (MAS) beim Masthähnchen

“…DieErgebnisseüberrasseabhängige Empfänglichkeit fürdas MASanverbreiteten Rassen decken sich mit Beobachtungen aus experimentellen Studien mitLegehennen-und Broilerküken (18) sowiem it Masthähnchenküken derR assen Cornish und White Plymouth/Rock ( 24), beid enen ebenfalls eine unterschiedliche Empfänglichkeitfür dasMAS festgestellt wurde. Der Rasseunterschied in derEmpfänglichkeit fürMAS wird in derEntwicklung desI mmunsystemsv ermutet, wobeid ie Ve rteilungd er CD4+-und CD8+-Zelleninder Darmmukosaeine Rolle spielenkönnte (24).…”