Internal parasites of cattle are capable of causing great economic loss, but the extent of this loss and the savings that can result from control of cattle parasites have only recently received serious attention. For the past several years extension animal husbandmen and veterinarians have reported with increasing frequency parasitic infections in cattle in the State of Virginia. Hence, the Animal Husbandry Department in conjunction with the Animal Pathology Department of the Virginia Polytechnic Institute initiated in the Autumn and Spring of 1953-1954 a survey in the State to obtain information concerning the incidence of bovine parasitism. Three methods have been utilized in diagnosing specific parasitism in domestic animals. Until recently the method commonly employed has been that of post mortem examination. In this type of examination the various digestive organs are tied off in place and then removed for examination for specific parasites. This method, while affording positive information on the one animal sacrificed, could not be regarded as giving sufficient information on the living animals unless a significant percentage of animals were autopsied. The second method is fecal culture which is usually regarded as too time consuming and involving the services of a technician skilled in identification of infective larvae. Lately, differential egg counts have been employed. This method has the advantage of quick diagnosis of mixed infections without loss of animals to slaughter. Therefore, more animals can be examined and a better estimate of the helminth population as a whole can be obtained. The principal disadvantage of this method lies in errors due to mis-identifications of the ova. The 1953-1954 survey employed the differential egg count method. The present study is an outgrowth of the problem of identifying, with reasonable accuracy, some of the commonly occurring species of nematode ova found in samples of cattle feces. / Master of Science

Internal parasites of cattle are capable of causing great economic loss, but the extent of this loss and the savings that can result from control of cattle parasites have only recently received serious attention. For the past several years extension animal husbandmen and veterinarians have reported with increasing frequency parasitic infections in cattle in the State of Virginia. Hence, the Animal Husbandry Department in conjunction with the Animal Pathology Department of the Virginia Polytechnic Institute initiated in the Autumn and Spring of 1953-1954 a survey in the State to obtain information concerning the incidence of bovine parasitism. Three methods have been utilized in diagnosing specific parasitism in domestic animals. Until recently the method commonly employed has been that of post mortem examination. In this type of examination the various digestive organs are tied off in place and then removed for examination for specific parasites. This method, while affording positive information on the one animal sacrificed, could not be regarded as giving sufficient information on the living animals unless a significant percentage of animals were autopsied. The second method is fecal culture which is usually regarded as too time consuming and involving the services of a technician skilled in identification of infective larvae. Lately, differential egg counts have been employed. This method has the advantage of quick diagnosis of mixed infections without loss of animals to slaughter. Therefore, more animals can be examined and a better estimate of the helminth population as a whole can be obtained. The principal disadvantage of this method lies in errors due to mis-identifications of the ova. The 1953-1954 survey employed the differential egg count method. The present study is an outgrowth of the problem of identifying, with reasonable accuracy, some of the commonly occurring species of nematode ova found in samples of cattle feces. / Master of Science