Genetic Selection for Resistance to Gastrointestinal Parasitism in Meat Goats and Hair Sheep through a Performance Test with Artificial Infection of Haemonchus contortus
by Yoko Tsukahara (IGA Board member), Terry A. Gipson (IGA member), Steven P. Hart (IGA member), Lionel Dawson, Zaisen Wang, Ryszard Puchala, Tilahun Sahlu (IGA Board member), and Arthur L. Goetsch (IGA member)
Internal parasitism has been an important constraint to small ruminant production and anthelmintic resistance has become a worldwide issue. This study evaluated a 3-year genetic selection program through activities on-farm and a centralized performance test and also provided estimates of genetic parameters of growth and response to artificial infection with Haemonchus contortus by goats and sheep in the southcentral USA. Considerable species as well as breed differences were found in average daily gain and response to parasite infection. Average daily gain was greater for Boer than for Kiko and Spanish goats and slightly greater for Dorper than for St. Croix sheep. Infection level (number of eggs found in feces) of Spanish and St. Croix were relatively low each year, whereas that of Kiko and Dorper was lower after selection. An indicator of anemia (packed cell volume) did not always reflect infection level, which is probably reflective of differences among animals in resilience and susceptibility to haemonchosis. Moderate to high heritabilities were found for growth performance and response to parasite infection for growing meat goat and hair sheep males under a standardized environment that suggests considerable potential for genetic improvement through selection.
The Newsletter of the E (Kika) de la Garza American Institute for Goat Research Cooperative Extension Program, Langston University
Production loss has many facets. According to the USDA/APHIS NAHMS report entitled "Goat and Kid Predator and Nonpredator Death Loss in the United States, 2015", by the way Mr. Branan is associated with this USDA program, about 500,000 adult and kid goats were lost to all causes (nonpredator and predator) in 2015, which represented 10% of U.S. adult goat inventory and 20% of kids born in 2015. The total value of goat and kid losses was $70 million. Texas had the largest inventory of goats and also had the highest percentage of losses: 36% of U.S. adult goat deaths and 38 % of kid deaths. Nonpredator causes accounted for about three-fourths of all adult goat and kid death losses in the U.S. in 2015. Of known losses due to nonpredator causes, internal parasites were the primary cause, resulting in almost 87,000 goat and kid deaths in 2015. For 2015 death losses due to predators, coyotes and dogs accounted for the highest percentages of goat and kid death losses in 2015. Overall, coyotes and dogs accounted for almost 80,000 goat and kid deaths, or about 65% of all losses due to predators.
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