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Forty-three gilts and 24 sows were tethered throughout gestation, and one-half were forced to walk on a treadmill 15 min daily 5 days a week. Exercised and nonexercised dams farrowed 10.0 and 10.2 pigs (P greater than .05) and weaned 8.1 and 7.9 (P greater than .05), respectively. Birth weight of pigs born alive from exercised and nonexercised dams averaged 1.6 and 1.5 kg (P greater than .05); weaning weights were 8.5 and 8.2 kg (P greater than .05), respectively. Sows farrowed 12% more pigs (P less than .05) than gilts and weaned 17% more pigs (P less than .05) that were 12% heavier at birth (P less than .01) than those of gilts. Forced exercise did not improve (P greater than .05) reproductive performance as measured by numbers of pigs farrowed and weaned or by birth and weaning weights. Mean length of gestation was not significantly affected by age of dam or exercise treatment. The interval between birth of first and birth of last pig per litter averaged 154 and 151 min (P greater than .05) for exercised gilts and sows, respectively, and 170 and 161 min (P greater than .05) for those not exercised.

Experiments were conducted at 12 and 22°C to compare the effects of aerobic and anaerobic treatment systems on the development and survival of eggs and larvae of swine nematode parasites. Swine feces containing eggs of Ascaris suum, Metastrongylus spp., Oesophagostomum dentatum, Hyostrongylus rubidus, and Strongyloides ransomi were used in both experiments. Treatment system fluids were sampled and examined periodically for the presence of parasite eggs and larvae. Cultures of fluids were prepared and examined for the presence of larvae after 7 days of incubation at 25°C. Ascaris eggs embryonated in 28 days in the 22°C aerobic system. Unembryonated Ascaris eggs in the other three treatment systems completed their development when transferred to 2% formalin at 25°C. Metastrongylus eggs survived in all treatment systems, but some larvae hatched and died in both aerobic systems. Oesophagostomum and Hyostrongylus larvae survived well under 12°C aerobic conditions, but were destroyed within 11 days at 22°C. Eggs of Strongyloides hatched rapidly under aerobic conditions, but survived at least 7 days under anaerobic conditions in both experiments. The development of free‐living adults of Strongyloides and the survival of third‐stage larvae were favored in 22°C aerobic conditions. Knowledge of the parasite genera present in a swine herd and of the responses of the eggs and larvae to different temperatures and treatment systems is important for effective management and safe recycling of wastes.

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increased in the surface 30 cm of the soil column. Salinity increased but not to the extent that plant growth was affected. Eighty percent of the applied phosphorus was removed. Routson and Wildung (1969) described the soil as a highly reactive system which can bind or alter the composition of waste solutions added to it by ion exchange capacity, buffer capacity, filter characteristics and microbial transformations. They report that the relative selectivity of typical low field strength clay minerals for any given ion is a function of ion valence and hydrated size. Selectivity usually follows the order m"*", for ions of increasing valence and increases with decreasing hydrated ion size. Thus, the expected order of selectivity for clay minerals is