Effects of gastrointestinal nematodiasis on the productivity of monozygous twin cattle. II. Growth performance and milk production.

Abstract

A study was conducted with homozygous twin heifers, beginning at less than 5 months of age, in which gastrointestinal nematodiasis was maintained very low in one number of each pair by frequent treatment with the anthelmintic, Cambendazole. A moderate natural infection, chiefly Cooperia species and Ostertagia ostertagi, persisted for one year in the non-treated heifers. Treatments were discontinued following parturition. Twenty-three pairs of twins completed lactation periods varying from 39 to 44 weeks. The treated animals produced significantly more milk, milk fat and fat-corrected-milk (FCM) than their controls, the increase in FCM amounting to an average of 191 kg or 6.58%. They also showed an advantage of weight gains of 29.3 kg at 16 months and 23.6 kg immediately prepartum. Compensatory gains occurred postpartum. During the first year of the study both feed intake and feed utilization by the treated animals were significantly improved. The diminished appetite and reduction of the serum albumin and albumin/globulin ratio of the non-treated animals was readily apparent. There were no significant differences between treatment groups in breeding performance or in the birth weight of their calves, with the exception that breeding of five sets of twins had to be delayed 1 to 3 months until the non-treated heifers reached the designated breeding weight. It was concluded that gastrointestinal nematode infection of young cattle can have a relatively long term deleterious effect upon growth performance as well as upon subsequent milk production during the first lactation period.