Phosphorus Kinetics in Calves Submitted to Single Infection with Cooperia punctata

The aim of this study was to evaluate phosphorus (P) kinetics in calves submitted to a single acute infection ofCooperia punctata, using isotopic dilution and modelling techniques. Ten Holstein calves were used, with a mean liveweight of 66.05 ± 0.30 kg. Of these, five received a single dose of 45 000 infectant (L3) C. punctata larvae and the otherfive were maintained in a control group without infection. Twenty one days after the infection, all animals received 29.6MBq 32P by intravenous injection to evaluate P kinetics. Weight gain, feed consumption and excretion in the faeces andurine were monitored and blood was collected for seven days. After the collection period, all animals were slaughtered, tissues collected and worms counted. The number of eggs per gram of faeces (EPG) reached 3 342 ± 194 and thenumber of adult worms was 12 992 ± 1 470. Final live weight, mean daily live weight gain, level of P in the plasma andits retention in control calves were higher and P excretion in the faeces less than in the infected calves. There was anegative P balance in both the control and infected calves for soft tissues and bone. A single infection by C. punctatanegatively influenced calf performance and P kinetics, leading to lower retention of the mineral.