Parasite Control

The use of fecal egg counts is a necessary tool of a parasite control program. It is the best and quickest way to determine if your dewormer is/isn't working. It is also the only way to really tell the level of infection of the Brown stomach worm or the Bankrupt worm since these worms do not cause anemia (they do cause diarrhea though) which is monitored through the FAMACHA system. You can learn to do your own fecal egg counts rather easily. There are instructions on how to do this on these web sites: www.SCSRPC.org and http://www2.luresext.edu/goats/training/herdhealthI.html (scroll to bottom).

The easiest way to monitor the need for deworming is to use the FAMACHA chart if the Barberpole worm is the problem species. The FAMACHA chart was developed in South Africa in response to dewormer resistance that was causing major problems in sheep production systems. The name of the chart is an acronym from the name of a famous South African parasitologist Dr. Fafa Malan with chart added to get FAMACHA. Although originally developed for use in sheep and it was successfully validated for use in goats in the USA through research support from Southern SARE. The validation exercise did include sheep as well as goats and involved several of the institutions that are currently a part of SCSRPC. This parasite management tool consists of a color chart for comparison of eye mucous membrane color and rules for proper use of the chart. Figure 1 shows a picture of the FAMACHA chart (actual chart is in color).

figure 1

FAMACHA is an important tool in an integrated parasite management program. It identifies animals that have a high enough level of the Barberpole worm infection to reduce animal productivity. Only those individuals need to be dewormed. Since the Barberpole worm sucks blood, the of resultant degree of anemia. will cause lost production or even death of the animal. Anemia is reflected in the color of the mucous membranes i.e. a healthy reddish-pink color reflecting no anemia, whereas pale mucous membranes reflect a degree of anemia. By monitoring the degree of anemia,(using eye mucous membrane color as an indicator) we can identify animals that need to be dewormed to prevent a loss in animal production and to prevent death. Usually only a portion of the animals in a herd need dewormed (animals to right of arrow as shown in figure 2). The remainder of animals are not dewormed which reduces the development of dewormer resistance which will be discussed in the next article. This also reduces dewormer expense.

figure 2

Mucous membranes that are readily observed are located on the inside of the eyelid, the gums (difficult to gauge anemia in animals with pigmented gums) and inside the vulva (often checked by dairy goat people when animals are being milked on a milk stand). The FAMACHA system was developed based on the eye mucous membrane, which is on the inside of the lower eyelid where it touches the eyeball. It is convenient to see the membrane by holding the animal=s head, slightly pressing down on the top of the eyeball (causes third eyelid to stay out of way), and pulling down on the skin immediately below the eyeball. The lower eyelid will roll out and can be readily compared to the FAMACHA chart. By using a series of color chips to match mucous membrane color, we can determine the degree of anemia and consequently, whether an animal needs to be dewormed. Since the Bankrupt worm and Brown stomach worm do not suck blood, FAMACHA will not bean effective indicator for controlling these species of worms. These worms are more prevalent during cooler times of the year and need to be monitored with fecal egg counts or monitoring animals for diarrhea. Your local veterinarian or animal extension specialist should be able to help you identify times of the year when these worm species are more prevalent.

The FAMACHA chart was originally brought into the US by the Southern Consortium for Small Ruminant Parasite Control. The agreement was that the chart could only be sold to Extension Educators, agricultural teachers and producers who had completed hands-on training following the specified curriculum (Some exceptions made for veterinarians and Extension Specialists who already had the prerequisite training). Training sessions are posted to the website (www.scsrpc.org) as well as further information about the FAMACHA chart. Most states have qualified trainers which can be identified through your state sheep or goat extension specialist. Some trainers are listed on the SCSRPC web site.

The FAMACHA chart is small enough to be fastened to the back of the hand for ready comparison when the lower eyelid is pulled down. The chart is calibrated for observing the eye of the animal in direct sunlight (the type of light may affect appearance of color, ask any woman about the effect of different kinds of light on makeup). Animals should be observed in direct sunlight and matched to the chart. Color memory is not as good as a person thinks (why do women take swatches of fabric to the store for matching?) Therefore, the chart should always be used for matching colors. If the animal's eye color is in between two chips, score as the lighter chip (higher number).

When scoring eyes, one should remember that some environmental factors can affect eye color and make the eye appear redder and make the animal not appear anemic. Factors include hot and/or dusty conditions which can irritate the eyes, infectious eye diseases (pink eye) and fever. In addition, remember that there can be other causes of anemia besides the Barberpole worm and deworming will not fix those anemias. Other causes includes liver flukes (most likely a problem in the Gulf Coast and Northwestern States), sucking lice, nutritional deficiency, bacterial and viral infections.

The frequency of checking eyes will vary with how suitable environmental conditions are for the Barberpole worm and age and class of the animal. Young animals need to be checked every two weeks because they are more susceptible to worms. In the spring, such as around kidding time, one may only check every 3-4 weeks, but when the weather warms up and you have rain (ideal conditions for the Barberpole worm are 85^oF and two or more inches of rain in a month's time), you may need to check as frequently as weekly. Many producers will only need to check every two weeks except when it is warm and rainy when they need to go to weekly eye examination. With large herds of goats, a random sample may be checked (don=t forget that animals that are anemic are often at the end of the line because they move slower due to anemia) and if 80% are 1 and 2's and there are no 4's or 5's then the herd is assumed OK. If there are 4's and 5's or more than 10% of the herd is a 3, then the whole herd should be examined.

Sheep or goats that score a 4 or 5 (pale) need to be dewormed and the rest turned back to the pasture. However, when over 10% of the flock are dewormed, the 3's should also be dewormed because pasture contamination is building and the 3's will need dewormed shortly. The flock should be rotated to a new pasture since present pasture has become highly contaminated with infectious larvae. In addition, pregnant animals, lactating animals and animals under a year of age should be dewormed when they are 3's since their immune system is not fully functional. Animals with bottle jaw (swelling under the chin caused by edema) should be dewormed and animals that lag behind the rest of the herd or those that look wormy should be dewormed.

It is important to know that the dewormer that you are using works. The best way to determine this is to take a fecal sample before deworming on several animals then deworm those animals. Take another fecal sample 7-14 days later on the same animals for a fecal egg count. There should be less than 15% of the eggs in the second fecal count as compared to the first count. If there are more than 15% of the eggs in the second fecal egg count as compared to the first one, the dewormer is not effective in your herd or flock. The dewormer should be changed and be sure to verify that the new dewormer is working for your sheep/goats. The next article in this series will cover selection of a dewormer.

To get the most out of this program, records should be kept on which animals are dewormed. Records may be as simple as recording eartag numbers or names and dates animals were dewormed. It is beneficial to be able to identify the animals that require the most deworming. These animals are candidates for culling. These animals need culled because they are producing most of the eggs (and infective larvae) for infecting other animals in the herd. Remember, 20-30% of the animals produce 70-80% of the eggs on a pasture. In addition, culling of these animals will improve the genetic base of the whole herd for resistance to the Barberpole worm. Several methods of marking animals are available to identify animals that were dewormed if there is not an individual animal identification. The ear may be notched each time the animal is dewormed or a wire tie may be placed around the cannon bone of the front leg with the tail of the tie cut off much like a bangel. The animals that accumulate the most wire tie bangels in a season or ear notches are candidates for culling.

Another record keeping tool that can be used is shown in Figure 3. It is a FAMACHA block histogram. It shows the proportion of animals in each FAMACHA score category at each time animals are checked. By keeping this record, a pattern will develop over time of what is happening in the herd as far as infection levels. That can provide background information for development/modification of the parasite control program. By watching changes in the relative proportion of FAMACHA categories of the herd, one can tell when animals need ti be checked more or less frequently.
figure 3

Since the determination of whether an animal needs to be dewormed is by comparison to the color chart, you need to protect the chart from fading. The chief cause of the color chart fading is sunlight, just as sunlight causes stop signs to fade. When the FAMACHA card is not being used, it should be stored in a dark area such as in a book or dark colored folder to exclude sunlight. Probably the worst place to put the card is on the dash of the pickup with the sun beating down on it. Despite your best efforts, the colors will eventually fade. It is recommended that the card be replaced every year so that you are sure that the colors are true. Replacement cards can be obtained from whoever you obtained the first card or from www.scsrpc.org web site.

Troubleshooting Barberpole worm problems

Routinely monitor sheep/goats for parasite infection level using FAMACHA chart.

Do only a few individuals (less than 20% of the herd) need dewormed?
Keep up with regular monitoring.
Do some individuals require the most deworming?

Solution, cull individuals requiring the most deworming because they have more worms and are causing most of the pasture contamination for other animals.

Do more than 20% of the herd need dewormed?
Has it been longer than 8 weeks since those animals were dewormed?

Keep up with regular monitoring and realize that level of pasture contamination may be building.

Possible causes:
a. Sheep or goats are picking up a many infective larva from the pasture which may be heavily infected with larva such as by having many animals on it a long time or having wormy animals on it during times of good rainfall. The solution is to move animals to another less infected pasture (deworm only animals that need to be when moving pastures). The old pasture will need to be without goats or sheep at least 6 weeks to reduce contamination. It can be cut for hay or grazed with a cattle or horses to reduce contamination.

b. Goats/sheep may be grazing close to the ground picking up many larva, causing worm problems. This can happen if the pasture is grazed low, or animals may graze favorite patches such as in bermuda grass or specific areas where their favorite plants are. The solution is to move animals to another pasture or reduce animal numbers or supplement animals so that they don't need to graze close to the ground. Patch grazing can be reduced by high stocking density in a rapid rotation grazing system.

c. Animal's immune system may be suppressed by lactation, shipping, poor nutrition (protein, energy and minerals) or other stress. Solution is to make sure animals have good nutrition (protein, energy, vitamins and minerals) and reduce stress. Since lactation suppresses the immune system, deworming around lambing/kidding time will help reduce worm problems. It is important to plan to use pastures which have a low level of infective larvae (such as pastures that have been rested a long period of time) for animals around kidding/lambing time and lactation.