Comparison of Natural Resistance to Internal Parasites Through (ELISA) and FEC in Barbados Blackbelly and Suffolk Crossbred Sheep

The purpose of this research was to evaluate differences in parasite resistance of Barbados blackbelly ewes and Suffolk crossbred ewes. 40 ewes were used for this study; 20 were Suffolk crossbreds and 20 were Barbados blackbelly. Fecal egg counts (FEC) verified that there were zero internal parasites in the sheep at the start of the experiment. The sheep were placed on a previously grazed pasture for seven weeks. Each week, FAMACHA eye color scores, FEC and blood samples were collected from each sheep. FAMACHA scores were not significantly different between the breeds (P>0.05), the FEC of the Barbados blackbelly ewes (256.3 eggs/g) was significantly lower than the Suffolk crossbreds (2741.2 eggs/g; P<0.001). An ELISA test was used to determine IgA levels in the blood serum. At the beginning of grazing, the differences between the two groups was not significantly different, however, total IgA serum levels had a significant difference between the test groups during the time on pasture. Barbados blackbelly ewes showed an increase in their total IgA serum levels by week five (0.969 O.D.) than Suffolk crossbred ewes (0.544 O.D.; P=0.009). IgA continued to increase in Barbados blackbelly ewes for one more week, but by week seven, levels decreased and were not significantly different from the Suffolk crossbreds. Serum antibody levels correspond to the FEC data of both breeds indicating that an increase of total IgA can have an impact on the parasite. All together, these data indicate that Barbados blackbelly ewes produce a greater immune response to parasite infection, reduce infection level, and are more resistant to gastrointestinal parasites than Suffolk crossbred sheep. Background Losses for sheep producers can be blamed on internal parasites (Zajac, Anne 2003). The Caribbean hair sheep is known to have a greater resistance to gastrointestinal nematodes, or known to the common sheep producer as worms. (Greiner, Scott 2004). However, traditional U.S. sheep breeds with European origins, for example the Suffolk, do not show this