Therefore, if we move animals to the next pasture after four days and before signif- icant rain, we should be able to avoid goats picking up most of the infective larvae. After we remove animals from the pasture, infective larvae are still being released, assuming sig- nificant rain, contaminating the pasture. How do we decontaminate the pasture? Infective larvae cannot eat because when they molted to an infective L3 larvae, it developed a protective sheath that covered their mouth. So, they have to get into your goat before they burn up all their fat/food stores and die. The time for larvae to burn up their fat depends on temperature since their metabo- lism runs faster in warm temperatures. An Australian study showed that 80% of the in- fective larvae died in 35 days at a constant temperature of 97°F, but 55 days at a tempera- ture of 70°F. Since it usually cools down at night on pastures, it will take longer than this. Generally, in the South, we talk about resting pastures 40-45 days and in the North, 60-90 days before grazing again. Native pas- ture species and browse will generally hold their quality over this time period. However, quality of improved forages pasture will deteriorate in this length of time. Pastures can be grazed by cattle or horses or hayed to keep the forage in a vegetative state during this wait period.


Organic farmers in New York mow their pastures very short after removing ani- mals. This sets the forage back for slower re- growth but allows the sun to kill some larvae. Langston did a study with moving goats every five days in a 12-pasture grazing system that provided a 55-day rest period. The system worked so well that we were sure that the 55 days rest was excessive and could be reduced. Another practice is to feed Bioworma to prevent pasture contamination. Bioworma contains spores of a fungus (Duddingtonia flagrans) that forms loops like small lariats in the fecal pellet that traps developing worm larvae and parasitizes them to form more fun- gal spores.


Several research studies have verified


the effectiveness of this fungus at virtually eliminating infective larvae in the fecal pel- let. The two downsides are that the spores have to be fed every day and it is pricey. For people with hobby herds concentrated on a small area, this could be very useful. Pre- sently, the product is marketed by Premier1. Despite our best efforts, some goats


will pick up sufficient larvae to become wormy and need to be dewormed. Giving a dewormer removes most or few worms de- pending on the worms’ resistance to the de- wormer. For every dewormer, there are a few worms in your animal that are resistant to


that dewormer due to the great genetic vari- ability in worms.


By repeated deworming, we kill off all the worms except for the resistant worms. The only way to tell for sure the level of re- sistance to a dewormer is to take a fecal egg count, deworm the animal and take a fecal egg count 1-2 weeks later.


Of course, you would do several ani- mals so results represent the whole herd in- stead of one animal and you want animals that have a significant level of worms. You calculate the % of eggs that disappeared due to deworming i.e. initial fecal egg count of 1,000 eggs per gram and post-deworming fecal egg count of 200 eggs per gram is an 80% fecal egg count reduction.


If you have less than a 95% fecal egg count reduction, resistance to that dewormer is present. If you have a fecal egg count re- duction of less than 55% there is a high level of dewormer resistance and your dewormer is not doing much good so you need to change to another class of dewormer or a combination of dewormers.


The best way to prevent the devel- opment of dewormer resistance is to use se- lective deworming — only deworm animals that need to be dewormed. This can be done with FAMACHA© and the 5-point check©. (Continued on Page 18)


14 Goat Rancher |


April 2025


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