Gain is primarily affected by number of fl ukes — the more fl ukes, the more impact.
supplemented by corn-based concentrate ration so they would gain a pound per day, to reach breeding weight,” he explains. The dewormed group gained an average of 23 to
25 pounds more than the control group, “which actu- ally did pretty well, gaining approximately 1 pound per day.” Hawkins says the untreated group gained 53 pounds, which was “more than necessary to be at their proper weight at breeding.” Due to the extra 23 to 25 pounds gained by the dewormed group, “that group could have been backed off a little on feed and still attained breeding weight, which would have saved money,” says Hawkins. The group that always did best, in all the years of
the study, was the group receiving both treatments — worm and fl uke control. “They had better weight gain and increased conception rates,” he says. For this study the cattle were naturally infested on
pastures known to have liver fl ukes and worms. Dur- ing their growing period, under these conditions, the worms were a lot more important than fl ukes in terms of affecting weight gain. “But if a producer sees signs of heavy fl uke infec- tions, this could be a different story. I’ve seen several
tscra.org
instances in which young cattle died on pasture from liver failure, so people need to be aware of this pos- sibility,” he explains.
Flukes affect conception rate In the Louisiana study comparing worm impact and
fl ukes, heifers were bred by artifi cial insemination (AI) after the growing period. “The interesting thing was fl ukes had a big impact
on conception rates. Even though the untreated control heifers were at proper weight at breeding, the concep- tion rate was dramatically reduced — to the point that Dr. Loyacano wondered why these heifers didn’t get pregnant like they should. So they decided to keep that group and follow them all the way through calving, to try to see what was going on,” Hawkins says. “The untreated heifers not only had low conception
and calving rates, but there was also a signifi cant reduc- tion in birth weight in their calves. One calf weighed only 26 pounds and did not survive. “What I’d been taught in veterinary school is that
conception is primarily dictated by body condition and proper weight at time of breeding. So I did a complete literature search and talked to other parasitologists.
April 2014 The Cattleman 73
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