Strategic treatments with IVOMEC 1% Injection produced significant productivity improvement.

Louisiana: Four groups of 16 crossbred beef steer calves were used to evaluate different parasite treatment schedules. Cattle were matched by weight and randomly allocated to four equivalent groups.

• Group 1 was treated with IVOMEC 1% Injection at weaning (October) and then grazed on pasture with minimal parasite contamination.
• Group 2 was treated with IVOMEC 1% Injection at weaning, and on two other occasions, in January and in April, and grazed on contaminated pasture.
• Group 3 was treated with IVOMEC 1% Injection at weaning and again in April, and grazed on contaminated pasture.
• Group 4 was treated at weaning with fenbendazole and grazed on contaminated pasture.

Group 4 cattle were also treated with fenthion in late October for lice control, and 6 of the 16 cattle in this group required additional treatment in February and April because of gastrointestinal parasitism. The trial continued for more than 11 months. The final body weight data are shown in the chart below.

Williams et al, 1989, AJVR, 50:2108-2116





Louisiana: Body weight performance of calves left untreated, treated twice with IVOMEC 1% Injection (Day 0 and Day 56) or once with IVOMEC SR Bolus (Day 0).

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Calves treated with the IVOMEC SR Bolus or IVOMEC 1% Injection (twice) showed significantly improved weight gain.

Louisiana: 90 crossbred steers, 8 to 10 months of age, were matched by weight and allocated among three treatment groups:

• Group 1 was left untreated as the Control group
• Group 2 received IVOMEC 1% Injection on Days 0 and 56
• Group 3 received IVOMEC SR Bolus on Day 0

Cattle grazed Bermuda grass/rye and clover pastures, and faecal egg counts and body weights were monitored from Days 0 to 168.
Despite the absence of a severe parasite challenge (the peak mean fecal egg count per gram in Controls was only 36), both groups treated with IVOMEC gained significantly more weight than Controls (P<0.05). Not only did the IVOMEC SR Bolus provide the convenience of avoiding repeated handling of cattle, but it also resulted in the best performance. Cattle treated with IVOMEC SR Bolus had a mean gain of more than 1.14 kg per day.

Williams et al, 1995, Vet Parasitol, 58:75-82

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Calves treated with the IVOMEC SR Bolus grew significantly faster than those treated three times with fenbendazole.

North Carolina: 441 crossbred steers (average weight 274 kg) were grazed on six pastures (spring/summer pastures) for 128 days. Steers were matched by weight and allocated between two treatment groups:

• Group 1 was treated once with the IVOMEC SR Bolus on Day 0
• Group 2 was treated three times with fenbendazole (oral suspension at 5 mg/kg at Day 0 and a mineral mixture at 5 mg/kg for two 5-day periods at Day 28 and Day 56)

The group treated with the IVOMEC SR Bolus gained significantly more weight than the group treated three times with fenbendazole (P<0.05). A random sampling of faecal egg counts (FEC) from 27 to 29 steers at the end of the trial indicated that the group treated with the IVOMEC SR Bolus had a FEC range of 0 to 1 whereas the group treated three times with fenbendazole had a FEC range of 0 to 234.

Rogers et al, 1998, Bov. Pract., 19-24

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Calves treated with the IVOMEC SR Bolus showed significantly improved weight gain.

Missouri (south/west): 56 crossbred calves were matched by weight and allocated between two treatment groups:

• Group 1 was left untreated as the Control group
• Group 2 was treated with the IVOMEC SR Bolus on Day 0

The cattle grazed fescue pasture with >90% endophyte (fungus) infestation for 168 days over the summer, when the potential for fescue toxicity was greatest. The Controls’ physical appearance and low faecal egg counts suggested a very low level of gastrointestinal parasite challenge. Despite this low parasite challenge and the grazing of infested fescue, the group treated with the IVOMEC SR Bolus finished 34 kg heavier (P<0.02) than Controls. Also, the trial shows that a low level of egg output can accumulate over a grazing period to a level in which parasite challenge has a significant negative economic impact.

Ryan et al, 1997, JAVMA, 211:754-756





Weight Gain Benefits of Missouri Trial
As pasture contamination slowly builds, so does the effect on weight gain.

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Calves treated with the IVOMEC SR Bolus grew significantly faster than those treated three times with fenbendazole.

North Carolina: 441 crossbred steers (average weight 274 kg) were grazed on six pastures (spring/summer pastures) for 128 days. Steers were matched by weight and allocated between two treatment groups:

• Group 1 was treated once with the IVOMEC SR Bolus on Day 0
• Group 2 was treated three times with fenbendazole (oral suspension at 5 mg/kg at Day 0 and a mineral mixture at 5 mg/kg for two 5-day periods at Day 28 and Day 56)

The group treated with the IVOMEC SR Bolus gained significantly more weight than the group treated three times with fenbendazole (P<0.05). A random sampling of faecal egg counts (FEC) from 27 to 29 steers at the end of the trial indicated that the group treated with the IVOMEC SR Bolus had a FEC range of 0 to 1 whereas the group treated three times with fenbendazole had a FEC range of 0 to 234.

Rogers et al, 1998, Bov. Pract., 19-24

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