TY - JOUR
T1 - Relationships between immune indicators of parasitic gastroenteritis, nematode burdens and faecal dry matter in sheep
AU - Williams, Andrew Richard
AU - Palmer, Dieter G
AU - Williams, Ian H
AU - Vercoe, Philip E
AU - Emery, David L
AU - Karlsson, L J E
PY - 2010
Y1 - 2010
N2 - Immune-mediated scouring in sheep is a mucosal hypersensitivity response caused by ingesting infective parasite larvae. In this experiment we tested the hypothesis that levels of parasite-specific antibodies and also interleukin-5 (IL-5) would be negatively correlated with worm numbers, but also faecal dry matter (FDM), in parasite-resistant Merino sheep. Forty Merino rams were challenged with Trichostrongylus colubriformis and Teladorsagia circumcincta larvae every day for 6 weeks, after which they were euthanised and total worm burdens determined. Faecal samples were taken for measurement of worm egg counts and FDM. Serum was collected from the rams before and after the larval challenge commenced, and levels of ovine immunoglobulin light chain, IgG, IgM, IgA and IgE specific for T. colubriformis and T. circumcincta as well as IL-5 were determined by sandwich enzyme-linked immunosorbent assay. IL-5 and all serum antibodies apart from T. colubriformis-specific light chain were significantly increased by the larval challenge. However, none of the antibodies, or IL-5, was correlated with FDM. Negative correlations were observed between the number of adult T. circumcincta and antibody levels; however, there was little relationship between antibodies and numbers of T. colubriformis. It was concluded that serum antibody levels are a poor indicator of the susceptibility of sheep to immune-mediated scouring. Because of these results, sheep breeders should continue to select for low worm egg count and focus on phenotypic indicators of scouring, such as dags, as a means to reduce diarrhoea.
AB - Immune-mediated scouring in sheep is a mucosal hypersensitivity response caused by ingesting infective parasite larvae. In this experiment we tested the hypothesis that levels of parasite-specific antibodies and also interleukin-5 (IL-5) would be negatively correlated with worm numbers, but also faecal dry matter (FDM), in parasite-resistant Merino sheep. Forty Merino rams were challenged with Trichostrongylus colubriformis and Teladorsagia circumcincta larvae every day for 6 weeks, after which they were euthanised and total worm burdens determined. Faecal samples were taken for measurement of worm egg counts and FDM. Serum was collected from the rams before and after the larval challenge commenced, and levels of ovine immunoglobulin light chain, IgG, IgM, IgA and IgE specific for T. colubriformis and T. circumcincta as well as IL-5 were determined by sandwich enzyme-linked immunosorbent assay. IL-5 and all serum antibodies apart from T. colubriformis-specific light chain were significantly increased by the larval challenge. However, none of the antibodies, or IL-5, was correlated with FDM. Negative correlations were observed between the number of adult T. circumcincta and antibody levels; however, there was little relationship between antibodies and numbers of T. colubriformis. It was concluded that serum antibody levels are a poor indicator of the susceptibility of sheep to immune-mediated scouring. Because of these results, sheep breeders should continue to select for low worm egg count and focus on phenotypic indicators of scouring, such as dags, as a means to reduce diarrhoea.
U2 - 10.1071/an09144
DO - 10.1071/an09144
M3 - Journal article
SN - 1836-0939
VL - 50
SP - 219
EP - 227
JO - Animal Production Science
JF - Animal Production Science
ER -
