Effect of purified immunoglobulins or pooled colostrum on performance of rearing calves

Fifty Belgian white-blue male calves, purchased from the market at about 10 days of age, were divided into three groups. The basic diet was the same for all calves, and consisted of a restricted amount of commercial milk replacer containing 50 ppm zinc bacitracin and 20 pm virginiamycin, calf starter and grass hay. Weaning occurred when daily starter intake over 7 consecutive days averaged 0.5 kg. Maximum starter intake was restricted to 3 kg day^-1, and grass hay was fed ad libitum. The experiment lasted 20 weeks. Group 1 (control) received the basic diet. Groups 2 and 3 were supplemented with either 2 g purified immunoglobulins (Ig) or 25-ml pooled colostrum (CO) twice daily, via the milk replacer as used in Group 1. Neither Ig nor CO exerted a positive effect on growth rate and feed efficiency. Six calves died: two, one and three in Groups 1, 2 and 3, respectively. Their serum IG content was significantly lower than that of the surviving animals. Mechanisms explaining the lack of any protective effect are discussed. It is supposed that the main reason was due to the gap between the CO feeding at birth and the onset of the administration of Ig or CO at the start of the experiment. At that time, 31 of the 50 calves excreted rota-and/or coronaviruses.