|NOTTER, DAVID - Virginia Tech|
|MILLER, JAMES - Louisiana State University|
|MORGAN, JAMES - Katahdin Hair Sheep International|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2017
Publication Date: 3/28/2017
Citation: Notter, D.R., Burke, J.M., Miller, J.E., Morgan, J.L. 2017. Association between FAMACHA scores and fecal egg counts in Katahdin lambs. Journal of Animal Science. 95(3):1118-1123.
Interpretive Summary: The FAMACHA system was developed in response to dewormer resistance in small ruminants to selectively determine animals in need of deworming. It is important to understand factors that influence FAMACHA scores among real farms in order to improve management of gastrointestinal nematodes. Scientists from Virginia Tech, Agricultural Research Service - Booneville, AR, Louisiana State University, and Katahdin Hair Sheep International determined that younger and lighter lambs will likely be more susceptible to parasitism and may need to be managed more diligently than older or heavier lambs. In addition, FAMACHA scores have potential to improve breeding value estimates in programs designed to genetically improve parasite resistance. This information is important to sheep producers, scientists, veterinarians, and extension specialists aiming to minimize parasite problems in sheep.
Technical Abstract: The FAMACHA system was introduced to the U.S. just over 10 yr ago in order to allow selective deworming of lambs with anemia associated with Haemonchus contortus and retard the development of anthelmintic resistance. The FAMACHA system was initially developed as a predictor of packed cell volume (PCV), but correlations between FAMACHA and fecal egg counts (FEC) have also been reported. It is important to understand factors that influence FAMACHA scores among farms in order to improve management of gastrointestinal nematodes. The objectives of this study were therefore to quantify associations between FAMACHA scores and FEC, BW, and age in Katahdin lambs at 2 different measurement times in 8 flocks in the eastern U.S., and to assess consistency of relationships between FAMACHA and FEC among flocks. Data came from 1,644 Katahdin lambs from 7 flocks sampled at approximately 90 d of age, and 1,295 lambs from 6 flocks at approximately 120 d of age over a 5 yr period. Residual correlations among log-transformed FEC (LFEC), FAMACHA scores, BW, and lamb ages at each measurement time were determined. Repeatability of each variable was also determined as residual correlations among repeated measures. At both 90 and 120 d of age, correlations of FAMACHA scores with LFEC and BW were significant (P < 0.001), but numerically modest (0.25 and -0.16, respectively at 90 d; 0.31 and -0.16, respectively at 120 d), demonstrating that higher FAMACHA scores were associated with higher FEC and more likely to be observed in lighter lambs. A small negative correlation was observed between FAMACHA score and lamb age (r = -0.05, P = 0.05, 90 d; r = -0.11, P < 0.001, 120 d) indicating that younger lambs were more likely to have elevated FAMACHA scores. Thus, younger and lighter lambs will likely be more susceptible to parasitism and may need to be managed more diligently than older or heavier lambs. In addition, FAMACHA scores have potential to improve breeding value estimates in programs designed to genetically improve parasite resistance.