Effect of ovine urine and some of its components on viability of nematode eggs and larvae in sheep faeces.

Sheep faeces incubated for 7 days at 27 degrees C for cultivation of third-stage nematode larvae were sprinkled daily with urine from sheep or with solutions of components normally occurring in sheep urine. Larval development was completely blocked in cultures sprinkled either with sheep urine, with solutions of 2 or 4% urea, or with urine from which urea or the phenol components had been extracted. Only a few third-stage larvae developed in cultures sprinkled with 1% urea. Normal larval development occurred in cultures sprinkled with either the phenol component from urine, or with solutions of 0.035% phenol, 0.035% p-cresol, 0.3% allantoin, 0.3% hippuric acid or 2.8% NaCl. Normal larval development also occurred in all control cultures sprinkled with water, including one culture where there was urine in the space between the outer and inner beaker used for cultivation. It is suggested that the inhibitory effect of urine on larval development is mainly caused by ammonia produced when urinary urea is brought into contact with urease of faecal origin. It is, however, an unsolved question why urine, from which urea had been removed, also inhibited larval development.