Farm survey used to guide estimates of nitrogen intake and ammonia emissions for beef cattle, including early season grazing and piosphere effects

Nitrogen cycling in pastoral livestock systems in Sub-Saharan Africa: knowns and unknowns

Pastoral systems are the dominant livestock production system in arid and semiarid regions of sub-Saharan Africa (SSA). They are often the only form of agriculture that can be practiced due to unfavorable climate and soil fertility levels that prevent crop cultivation. Pastoralism can have negative impacts on the environment, including land degradation, greenhouse gas emissions and other gases to the atmosphere, soil erosion, water pollution and biodiversity loss. Here, we review the current knowledge on nitrogen (N) cycling, storage, and loss pathways, with an emphasis on identification of N emission hotspots. Our review reports a large uncertainty in the amount of N lost as ammonia from excreta and manure storage, as well as N losses via nitrate and DON leaching. We also found that another major N loss pathway (18%), soil N₂ emissions, has not yet been measured. In order to summarize the available information, we use a virtual pastoral farm, with characteristics and management practices obtained from a real farm, Kapiti Research Station in Kenya. For outlining N flows at this virtual farm, we used published data, data from global studies, satellite imagery and geographic information system (GIS) tools. Our results show that N inputs in pastoral systems are dominated by atmospheric N deposition (˜80%), while inputs due to biological nitrogen fixation seems to play a smaller role. A major N loss pathway is nitrogen leaching (nitrate > DON) from pastures (33%). Cattle enclosures (bomas), where animals are kept during night, represent N emissions hotspots, representing 16% of the total N losses from the system. N losses via ammonia volatilization and N₂ O were four and three orders of magnitude higher from bomas than from the pasture, respectively. Based on our results, we further identify future research requirements and highlight the urgent need for experimental data collection to quantify nitrogen losses from manure in animal congregation areas. Such information is needed to improve our understanding on N cycling in pastoral systems in semiarid regions and to provide practical recommendations for managers that can help with decision-making on management strategies in pastoral systems in semiarid savannas.

Changes in land, feed, and manure management practices on beef operations in Canada between 2005 and 2011

The objective of this paper was to evaluate changes in management practices of beef cattle from 2005 to 2011. Large nationwide surveys of husbandry practices in the beef industry were conducted to represent management practices used in 2005 and 2011 across Canadian Ecoregions. The two surveys attempted to similarly represent operation types (cow–calf, backgrounding, and finishing) and size. Several statistically significant changes in management practices from 2005 to 2011 were observed: in non-feedlot operations, these included more operations with >50% legume in perennial forage, less N fertilization applied to forages, increased winter grazing of cows, and higher quality feed used as a supplement to grazing. In feedlots, there were more shelter structures, less feeding of grain and more of high-legume forages, and more frequent removal of manure. Several practices remained constant in the two surveys including use of covers for storing hay, frequency of harvesting forage, time of barn and feedlot cleanout, manure storage and practices relating to manure incorporation into soil. The large increase in use of winter grazing on the Prairies as well as in eastern Canada documented here is an important change in the industry that has both economic and environmental implications.

Beef cattle husbandry practices across Ecoregions of Canada in 2011

Sheppard, S. C., Bittman, S., Donohoe, G., Flaten, D., Wittenberg, K. M., Small, J. A., Berthiaume, R., McAllister, T. A., Beauchemin, K. A., McKinnon, J., Amiro, B. D., MacDonald, D., Mattos, F. and Ominski, K. H. 2015. Beef cattle husbandry practices across Ecoregions of Canada in 2011. Can. J. Anim. Sci. 95: 305–321. Beef production in Canada is diverse in many dimensions with numbers of cattle per operation ranging over 10 000-fold, pasture usage from nil to 100%, and types of operations from solely cow–calf to exclusively feedlot finishing. This study summarizes management information obtained from a survey conducted in 2012 (about 2011) on 1009 beef operations in Canada. Many of the results clearly differentiate the practices in the Prairies from those in Ontario and Quebec. Compared to eastern Canada, the Prairies had earlier and shorter calving seasons, higher weaning weights, utilized more winter grazing with a variety of strategies, grew and fed more barley than corn, used more seasonal feeding areas and feedlots (and hence fewer barns), and more commonly spread manure in the fall. Many of the management practices used by cow–calf operations would have low environmental impact, including extensive use of grazing even in winter, low fertilizer inputs and feeding perennial forages with a high content of legumes. Some practices such as not covering forages or manure storage structures were common and could be changed to improve forage quality and reduce manure emissions. Most forage was harvested 3–7 d after full bloom. Earlier harvest has the potential to improve forage quality, which could reduce dependence on arable crops. Finishing operations used more housing, fed more arable-land crops and less perennial forages, and practiced little grazing. Rationale regarding the adoption of many of the management strategies was reported by the producers. For example, winter grazing was adopted primarily to reduce costs and labour, but for some it was also linked to a late calving season. Preferred sources of technical information included their own experience, farm print media, producer organisations and demonstrations at field days. The survey also identified several areas in which the industry may realize improved sustainability.

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.

Trace elements in feed, manure, and manured soils

Modern animal feeds often include nutritional mineral supplements, especially elements such as Cu, P, Se, and Zn. Other sources of trace elements also occur in livestock systems, such as pharmaceutical use of As and Zn to control gut flora, Bi in dairy for mastitis control, and Cu as hoof dips. Additionally, potential exists for inadvertent inclusion of trace elements in feeds or manures. There is concern about long-term accumulation of trace elements in manured soil that may even exceed guideline "safe" concentrations. This project measured ∼60 elements in 124 manure samples from broiler, layer, turkey, swine grower, swine nursery, sow, dairy, and beef operations. The corresponding feeds were also analyzed. In general, concentrations in manure were two- to fivefold higher than those in feed: the manure/feed concentration ratios were relatively consistent for all the animal-essential elements and were numerically similar for many of the non-nutrient elements. To confirm the potential for accumulation in soil, total trace element concentrations were measured in the profiles of 10 manured and 10 adjacent unmanured soils. Concentrations of several elements were found to be elevated in the manured soils, with Zn (and P) the most common. One soil from a dairy standing yard had concentrations of B that exceeded soil health guideline concentrations. Given that the Cu/P and Zn/P ratios found in manure were greater than typically reported in harvested crop materials, these elements will accumulate in soil even if manure application rates are managed to prevent accumulation of P in soil.