An important component of summer management for sheep and goat owners is internal parasite control. By this point in the calendar year sheep and/or goats on many farms have rotated through pasture paddocks at least a couple of times.
Lactating ewes and does often shed large numbers of parasite eggs, effectively seeding pasture paddocks with parasite larvae that are waiting to be ingested with the next grazing pass. As young lambs and kids learn to graze at the side of their mothers, they are very susceptible to acquiring large parasite infections.
Over the past several years, targeted selective deworming treatment of sheep and goats has been promoted as one way to avoid treating the entire flock or herd. Selective treatment can slow down the process of the parasite acquiring chemical resistance and thereby prolong the effectiveness of those chemical dewormers available to sheep and goat owners. One tool that is being used to determine selective treatment is the FAMACHA system.
The FAMACHA system utilizes an eyelid scorecard that can help a farmer make a decision to treat or not to treat the animal with a chemical dewormer. In order for this tool to be effective it must be used correctly.
To begin with, the FAMACHA scoring system is useful only for Haemonchus contortus infections. Haemonchus contortus is the parasite of greatest concern to pasture-based sheep and goat production, so FAMACHA is a good fit. The Haemonchus contortus parasite is a blood sucking parasite and heavy infestations result in anemia. The symptoms of anemia show up in the color of the membrane of the eye. In the FAMACHA system that eyelid color is matched up with a scorecard that ranks color on a 1 to 5 scale. A dark red eyelid membrane color is a 1 and indicates no significant anemia. A white color is a 5 and indicates severe anemia. The light red, pink and pinkish white colors in between indicated by scores 2 through 4 indicate increasing levels of anemia that generally correspond to the parasite burden the animal is carrying.
Use the FAMACHA score to make decisions about selectively deworming animals. In general, if an animal scores a 3, 4 or 5 it is treated with a chemical dewormer. Animals scoring a 1 or a 2 are not treated. Selective deworming is important to minimize parasite resistance to chemical dewormers. Mid-June through September are traditionally months of heavy Haemonchus contortus infections. Due to their smaller blood volumes, lambs and kids with heavy infections can go from apparently healthy to death's doorstep in 10 to 14 days. This means that animals should be FAMACHA scored every 7-10 days during this period.
I have heard livestock owners say that they grabbed a couple of animals out on pasture and looked at their eyes. This quick spot check of a couple of animals is used to determine the parasite burden of the flock or herd. This is not a correct use of the FAMACHA system and is not likely to provide accurate information. Research has demonstrated that 20 percent of the animals in a flock or herd can carry 60 percent to 80 percent of the worm load. If a majority of the animals are not checked, how do you know if the animal grabbed was one of those 20 percent that has a heavy parasite burden, or an animal with a relatively low burden? In addition, correct use of the FAMACHA system dictates that a scorecard is used each time eyes are checked. Do not rely upon memory of scorecard colors.
To really get a handle on what is happening with regard to infection levels in the flock/herd, FAMACHA scores should be recorded and the livestock owner should look for trends. Are the number of animals that scored a "1" or a "2" staying the same over scoring periods or is there an increasing percentage of 2s, and some 3s while the number of animals scoring a 1 is decreasing? If the trend is toward higher scores then that is an early warning that pastures have a high level of parasite eggs and infective L3 larvae and that animal infection levels are increasing.
For more information about internal parasite management in sheep and goats and/or the FAMACHA system, contact the Wayne County Extension office at 330-264-8722.
Rory Lewandowski is an OSU Extension Agriculture and Natural Resources educator and may be reached at 330-264-8722.