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

摘要: 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) the bovine liver fluke (Fasciola hepatica) differentiate losses attributable each type of parasitism. Each year, weaned allotted one treatment regimens: Group 1, untreated controls; 2, treated for nematodes; 3, fluke; 4, both fluke. Nematodes controlled with subcutaneous injections either ivermectin (Ivomec, Merial) or doramectin (Dectomax, Pfizer), at recommended dose 200 ug/kg bodyweight. Clorsulon (Curatrem, drench was given rate 7 mg/kg bodyweight control flukes. Treatments fecal collections initiated allotment year repeated 28-84-day intervals until palpation pregnancy diagnosis. Open removed from study this time. Treatment dates based on expected length efficacy, stage growth seasonal risk infection parasites. Pregnant females pooled received their assigned treatments prior calving breeding seasons remained together calves weaned. Heifers nematode infections heavier had higher condition scores (P<0.01) than initiation breeding, maintained that difference through Liver did not affect heifer gains (P<0.01). At palpation, forms parasitism highest weight (P<0.01), also rates only Pregnancy flukes significantly different those (P<0.05).