Effect of a once-daily suckling program on gastrointestinal parasitism in Angus cows and calves

SUMMARY Over a 2-year period involving a total of 168 Angus cows and their calves, 2 studies were conducted to evaluate the effect of once-daily suckling on cow reproduction, calf growth, and gastrointestinal parasitism. Experiment I compared 2 restricted suckling (rs) groups with 1 normal suckling (ns) group. Each group consisted of 24 cows with their calves (24 cows-calves/group = 24 cows and 24 calves/group). In the rs groups, suckling by the calves was restricted to once a day for 45 days, and then the calves were allowed to suckle normally throughout the remainder of the experiment. In the ns group, the calves suckled normally throughout the experiment. Experiment II compared 2 groups of rs cow-calves (24 cow-calves/group) with 2 groups of 24 ns cow-calves/group. In experiment I, there were ne differences (P < 0.05) in pregnancy rate or in the average number of nematode eggs/g of feces (epg) between the cows from the 2 treatment groups. The rs calves consistently had higher epg counts than did the ns calves during the 45 days of rs (169 vs 62 epg, P < 0.05) and from the time of their return to pasture until weaning (266 vs 186 epg, P = 0.27). The rs calves also had a higher average coccidia oocyst count during the rs period only. In experiment II, rs cows had a higher pregnancy rate (87.6% vs 66.0%, P < 0.05) and a shorter postpartum interval (83 vs 101 days, P < 0.05) than did ns cows. There was no difference in epg from cows, but the rs calves had higher epg during the rs period (160 vs 115, P = 0.19) and during the pasture period (329 vs 154, P < 0.05) than did the ns calves. In both experiments, ns calves had higher (P < 0.05) adjusted 205-day weights and actual weaning weights than did the rs calves. In experiment I, adjusted 205-day weights for the ns and rs calves were 160.1 and 129.0 kg, respectively. In experiment II, adjusted 205-day weights for ns and rs calves were 148.7 and 121.9 kg, respectively. Under the conditions of the present study, the rs technique improved conception rates in young cows, but resulted in lighter calves with a higher degree of internal parasitism.