Internal parasites are estimated to cost the U.S. cattle industry over $2.5 billion annually. Parasite burdens have been reported to decrease animal appetite, feed efficiency, ADG and total gain performance. Parasites also have potential to negatively affect reproductive performance of cows and developing heifer calves due to their effect on gain performance. According to the USDA’s National Animal Health Monitoring System, only slightly over 40% of replacement heifers and cows are dewormed at least one time a year.
A recent study focused on the effects of deworming on the gain performance of replacement heifers. The study took place during the summer of 2014, with 83 head of replacement heifers located at University of Arkansas Research Station near Fayetteville. The heifers were allocated to one of three deworming treatments based on body weight, fecal egg counts and days of age. The three treatments were 1) negative control (no dewormer); 2) a combination of a full label dose of Cydectin pour-on and a full label dose of Synanthic drench (Combo); and 3) a label dose of LongRange injectable treatment (Table 1).
Heifers grazed in multiple groups, with only one treatment represented per grazing group, and had access to forage available in the assigned pasture and were fed a corn gluten supplement at 1% of body weight daily. Heifers were processed for body weights and fecal egg counts on multiple dates throughout the study (Table 2).
Over the 84-day study, heifer body weights (Table 3) were similar on day 0, 14, 28; however, heifer body weights were greatest for LongRange treated heifers, intermediate for Combo heifers and least for the Control groups. Heifer average daily gain (ADG) overall was highest for LongRange treated heifers at 1.52 lb/day, intermediate for combo treated heifers at 1.2 lb/day and least for negative control heifers at 1 lb/day.
Fecal egg counts were similar amongst heifers on day 0. On day 14, Combo and LongRange treated heifers exhibited lower fecal egg counts compared to control heifers. LongRange and Combo heifers were similar on day 28 and again had lower fecal egg counts compared with the control treated group. Control heifers exhibited the highest fecal egg counts on day 84, the Combo treated group was intermediate, and LongRange heifers had the lowest fecal egg counts.
In this study, treatment against gastrointestinal nematodes positively impacted replacement heifer body weights, ADGs, and fecal egg counts. LongRange treated heifers reported the strongest benefit over the 84-day study period