FAMACHA© scores are a predictor of packed cell volume (PCV) and the need for deworming individual animals. They are a measure of resilience, whereas fecal egg counts (FEC) are a measure of resistance. Can FAMACHA© be used to select for resistance in a flock? Just how well do FAMACHA© scores correlate with FECs and other traits, such as body weight (BW) and age.
Data from 1644 Katahdin lambs from 7 flocks were sampled at approximately 90 days of age. Data from 1295 Katahdin lambs from 6 flocks were sampled at approximately 120 days of age. Residual correlations among log-transformed FEC (LFEC), FAMACHA© scores, BW, and lamb ages at each measurement time were determined.
At both 90 and 120 days of age, correlations of FAMACHA© scores with LFEC and BW were statistically significant, but numerically modest, 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 indicating that younger lambs were more likely to have elevated FAMACHA© scores.
FAMACHA© scores have potential to improve breeding value estimates in programs designed to genetically improve parasite resistance.
Source: Journal of Animal Science. March 2017. Read abstract.