Beef herd health and productivity and exposure to the petroleum industry in west-central Alberta

Health and productivity of cow-calf herds surrounding a new sour gas processing plant have been monitored from the fall of 1991 through to the calfing season in 1997. No significant change in the risk of non-pregnancy, abortion, stillbirth, calf mortality, median calfing date or crude weaning date have been found. There was measurable improvement in average age-adjusted weight for both male and female calves. Exposure to hydrogen sulfide and the complex mixture of compounds found in emissions from sour gas processing plants did not appear to have affected productivity parameters across the cow-calf production cycles examined, although there have been five examples of positive association between increasing exposure to total sulfation and decreased productivity. Increased risk of non-pregnancy was occasionally observed to be associated with one or more of sour flaring battery facilities, all battery flaring sites, active gas wells, and larger field facilities, however, these associations were not consistent among years . Risk of abortions did not increase with proximity of facilities or flaring. Examples of positive correlation were observed between volume of sour gas flared from battery sites and increased risk of stillbirth, sour gas and increased calf mortality, and exposure to oil well or all well sites and increased productivity