Dependence of ammonia emissions from housing on the time cattle spent inside

Farm practices as they affect NH3 emissions from beef cattle

Sheppard, S. C. and Bittman, S. 2012. Farm practices as they affect NH 3 emissions from beef cattle. Can. J. Anim. Sci. 92: 525–543. Beef cattle farms in Canada are very diverse, both in size and management. Because the total biomass of beef cattle in Canada is larger than any other livestock sector, beef also has the potential for the largest environmental impact. In this study we estimate NH3 emissions associated with beef cattle production across Canada using data on farm practices obtained from a detailed survey answered by 1380 beef farmers in 11 Ecoregions. The farms were various combinations of cow/calf, backgrounding and finishing operations. The proportion of animals on pasture varied markedly among Ecoregions, especially for cows and calves, and this markedly affected the estimated NH3 emissions. The crop components of feed also varied among Ecoregions, but the resulting crude protein concentrations were quite consistent for both backgrounding and finishing cattle. Manure was stored longer in the west than in the east, and fall spreading of manure was notably more common in the west, especially when spread on tilled land. The estimated NH3 emissions per animal were relatively consistent across Ecoregions for confinement production, but because the proportion of animals on pasture varied with Ecoregion, so did the overall estimated NH3 emissions per animal. Temperature is a key factor causing Ecoregion differences, although husbandry and manure management practices are also important. Hypothetical best management practices had little ability to reduce overall emission estimates, and could not be implemented without detailed cost/benefit analysis.

Ecoregion and farm size differences in dairy feed and manure nitrogen management: A survey

Sheppard, S. C., Bittman, S., Swift, M. L., Beaulieu, M. and Sheppard, M. I. 2011. Ecoregion and farm size differences in dairy feed and manure nitrogen management: A survey. Can. J. Anim. Sci. 91: 459–473. This paper describes the activity of dairy farmers in Canada in 2005 related to the use of nitrogen (N) and especially practices that led to loss of ammonia (NH3). The data were obtained from a large-scale, statistically structured survey conducted across Canada. The survey sampling was stratified into 10 Ecoregions and across farm size. Numbers of lactating cows per farm were nearly twofold more in the west than the east. In western Canada less than 31% of barns were “tie-stall” type whereas 80% were tie-stall in the St. Lawrence Lowlands. The numbers of hours lactating cows spent in barns, standing yards, exercise fields and pasture varied with Ecoregion and farm size, important data in relation to NH3 emissions. Pasturing was more common in the east than west. Matching feed crude protein concentrations to physiological needs seems a potential best management practice, and smaller farms with tie-stalls seemed more prone to adjusting feed to individual cows compared with large farms with loose housing. Manure handling was divided, with slurry prominent especially in the west. Manure spreading practices also varied by Ecoregion. Overall, it is clear that national averages do not well represent dairy farm management: Ecoregion and farm size differences are significant.