Wednesday, September 18, 2013

A Wormy Summer

Each year, bucks in the test endure different environmental conditions. This year's conditions resulted in a significant parasite challenge. The challenge was early and severe. Fecal egg counts increased rapidly from day 0 to day-28. Thirty-one, 59, and 25 percent of the goats were dewormed, respectively, on days 14, 28, and 42.

In fact, more goats were dewormed this year than in previous years. During the periods in which the parasite challenge was most severe (days 14-42), all goats with FAMACHA© scores were dewormed, usually with levamisole. When the number of animals with FAMACHA© scores of 4 and 5 increases in a herd, it is recommended that animals (especially kids) with FAMACHA© scores of 3 be dewormed. The test followed this recommendation.

The downside to deworming FAMACHA© 3's is that it complicates interpretation of the fecal egg count data. The fecal egg count that follows a deworming is excluded from the data set, giving a treated buck fewer observations. In fact, treated goats tended to have lower average fecal egg counts than untreated goats.

Six goats in the test were not dewormed: 310 (Adams, IL), 363 (Smith, VA), 378 (Wilborn, AL), 382 and 383 (Zink, IN), and 388 (Burke, DE). Of the untreated bucks, 388  had the lowest average fecal egg count.

The goats had a four-week break from parasites while they were grazing forage sorghum. Once this forage resource was depleted, the goats were returned to the infected cool season grass paddocks. Egg counts increased again and approximately 26 percent of the goats were dewormed on day-72.  Only one goat required deworming on the last day of the test, but all of the goats were given 0.5 grams of copper oxide wire particles (COWP) by mouth.

The graphs in this blog entry summarize the parasite data from this year's test. All fecal egg counts were used to calculate averages. Obviously, dewormings had an effect on average fecal egg counts. For most goats, deworming with levamisole greatly reduced the subsequent fecal egg counts. If fecal egg counts from treated goats are removed from the data set, the average fecal counts would be significantly higher than those shown in the graphs. Treatments also improved average FAMACHA© scores.

Fecal egg counts from the goats in the pen vs. pasture study are included as  means of comparison. None of the pen goats were  dewormed and their fecal egg counts were low throughout the duration of the study/test. Their average FAMACHA© scores were also lower (superior).

This year's parasite data is also compared to last year's. Though last year's egg counts got higher, the parasite challenge occurred later in the summer and did not result in a significant clinical challenge (or risk). Last  year's goats were given a small dose (1,000) of infective worm larvae, whereas this year's goats grazed infected pastures (pre-infected by untreated sheep).

This year's goats were also more "naive," (to infection) as evidenced by their low incoming fecal egg counts (avg. 324 epg), whereas last year's goats came in with very high fecal egg counts (avg 2532 epg). Last year's goats also had poorer FAMACHA© scores (avg. 2.2) upon arrival, whereas this year's goats had better FAMACHA© scores (avg. 1.8).

Download final FECreport -- updated 09.19.13
Download FEC rankings -- updated 09.19.13
Download final FAMACHA© report
Download FAMACHA© rankings