Effect of gastrointestinal nematode and liver fluke infections on weight gain and reproductive performance of beef heifers

• Published in: Veterinary parasitology 2002-08, Vol.107 (3), p.227-234
• Main Authors: Loyacano, A.F, Williams, J.C, Gurie, J, DeRosa, A.A
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Antinematodal Agents - therapeutic use; Antiprotozoal Agents - therapeutic use; Beef cattle:Nematoda; Beef cattle:Trematoda; Birth Weight; Cattle; Cattle Diseases - drug therapy; Cattle Diseases - parasitology; Cattle Diseases - physiopathology; Cattle performance; Fasciola hepatica; Fascioliasis - complications; Fascioliasis - drug therapy; Fascioliasis - parasitology; Fascioliasis - veterinary; Feces - parasitology; Female; Gastrointestinal nematodes; Ivermectin - therapeutic use; Louisiana; Male; Ostertagia; Ostertagiasis - complications; Ostertagiasis - drug therapy; Ostertagiasis - parasitology; Ostertagiasis - veterinary; Parasite Egg Count; Parasitism effects; Pregnancy; Random Allocation; Weight Gain - drug effects
• ISSN: 0304-4017; 1873-2550
• DOI: 10.1016/S0304-4017(02)00130-9

Spring born, crossbred beef heifers ( n=372) were utilized over four years to measure reductions in body weights, reproductive performance and calf weights caused by gastrointestinal nematodes (primarily Ostertagia ostertagi) and the bovine liver fluke ( Fasciola hepatica) and to differentiate losses attributable to each type of parasitism. Each year, weaned heifers were allotted to one of the four treatment regimens: Group 1, untreated controls; Group 2, treated for nematodes; Group 3, treated for liver fluke; and Group 4, treated for both nematodes and liver fluke. Nematodes were controlled with subcutaneous injections of either ivermectin (Ivomec ®, Merial) or doramectin (Dectomax ®, Pfizer), both at the recommended dose of 200 ug/kg bodyweight. Clorsulon (Curatrem ®, Merial) drench was given at the recommended rate of 7 mg/kg bodyweight to control flukes. Treatments and fecal collections were initiated at allotment each year and were repeated at 28–84-day intervals until palpation for pregnancy diagnosis. Open heifers were removed from the study at this time. Treatment dates were based on expected length of treatment efficacy, the stage of growth of the heifers and the seasonal risk of infection by the parasites. Pregnant females were pooled and received their assigned treatments prior to their calving and breeding seasons and remained together until their calves were weaned. Heifers treated for nematode infections were heavier and had higher condition scores ( P