Ontario Farm Research Articles

Methane emissions from storage of digestate at a dairy manure biogas facility

Conventional manure storages are an important source of methane (CH4), a potent greenhouse gas. Anaerobic digestion is an alternative manure management practice potentially able to provide environmental benefits, including the reduction of CH4 emissions from slurry storage. This study was conducted at a commercial farm in Ontario where a biodigester system became operational in May 2012. The purpose was to quantify year-round CH4 emissions from a digestate storage tank, examine the relationship between emissions and its driving factors, and compare these results to a similar emissions dataset from untreated manure measured during one year before the biodigester became operational. A micrometeorological mass balance approach was used to measure CH4 fluxes. Total annual CH4 emissions from digestate were 1.0 kg m−3 y−1, which was 85% lower compared to untreated manure. Monthly average volatile solids (VS) mass in the storage tank was 73 ± 24 Mg for digestate and 107 ± 30 Mg for manure, representing a 32% VS reduction in the tank, suggesting that lower emissions were not only due to VS mass reduction after biodigestion and solid-liquid separation. The annual CH4 emissions scaled by VS were 26 g kg−1 VS y−1 for digestate and 76 g kg−1 VS y−1 for manure, suggesting that VS in the digestate were less suitable for CH4 production (less digestible). This was also verified when investigating the relationship between fluxes and its driving factors: VS concentration did not correlate with CH4 emissions per volume for digestate (r = 0.37; p = 0.29), but did for untreated manure (r = 0.95; p = 0.002). However, the correlation of temperature with emission was stronger for digestate than manure at all depths with no lag, especially at 2 m depth (r = 0.98, p < 0.001). At the same air temperature, digestate was warmer than manure, owing to the digestate leaving the digester at 38 °C. This study showed that co-digestion of dairy manure and off-farm materials (35% of loading volume) with a 60-day hydraulic retention time and subsequent solid liquid separation significantly reduced facility-scale CH4 emissions from the storage tank.

Modeling livestock population structure: a geospatial database for Ontario swine farms

BackgroundInfectious diseases in farmed animals have economic, social, and health consequences. Foreign animal diseases (FAD) of swine are of significant concern. Mathematical and simulation models are often used to simulate FAD outbreaks and best practices for control. However, simulation outcomes are sensitive to the population structure used. Within Canada, access to individual swine farm population data with which to parameterize models is a challenge because of privacy concerns. Our objective was to develop a methodology to model the farmed swine population in Ontario, Canada that could represent the existing population structure and improve the efficacy of simulation models.ResultsWe developed a swine population model based on the factors such as facilities supporting farm infrastructure, land availability, zoning and local regulations, and natural geographic barriers that could affect swine farming in Ontario. Assigned farm locations were equal to the swine farm density described in the 2011 Canadian Census of Agriculture. Farms were then randomly assigned to farm types proportional to the existing swine herd types. We compared the swine population models with a known database of swine farm locations in Ontario and found that the modeled population was representative of farm locations with a high accuracy (AUC: 0.91, Standard deviation: 0.02) suggesting that our algorithm generated a reasonable approximation of farm locations in Ontario.ConclusionIn the absence of a readily accessible dataset providing details of the relative locations of swine farms in Ontario, development of a model livestock population that captures key characteristics of the true population structure while protecting privacy concerns is an important methodological advancement. This methodology will be useful for individuals interested in modeling the spread of pathogens between farms across a landscape and using these models to evaluate disease control strategies.

Year-round methane emissions from liquid dairy manure in a cold climate reveal hysteretic pattern

Liquid dairy manure storage is favourable for methane (CH4) production and a significant source of this greenhouse gas. Manure storage in cold climates faces large temperature variations over the course of a year, and added on-farm complexities in manure loading require year-round measurements which are currently lacking. The objectives of this study were to 1) quantify CH4 emissions from farm-scale liquid dairy manure storage in a cold climate, 2) investigate the effect of manure temperature on CH4 emissions, and 3) compare measured CH4 emissions with values derived from the USEPA temperature model. Methane fluxes were measured from Aug 2010 to early Nov 2011 on a commercial farm in Ontario, Canada, using a micrometeorological mass balance method which relied on 3 towers with air intakes at 4 heights placed around the storage tank. Manure temperature and volatile solid content (VS) were also measured. Monthly CH4 emissions scaled by VS decreased from 43.8 g CH4 kg−1 VS in Sep 2010 to 5.3 g CH4 kg−1 VS in Jan 2011, and were correlated with temperature (r2 = 0.94). Manure temperature increased starting in Feb 2011, but the increase in CH4 emissions was delayed to Jul 2011. Hence, the response of CH4 emissions to temperature showed a hysteretic pattern where emissions in the warming branch after the winter (Apr-Jun) were significantly lower than emissions in the cooling branch after the summer (Sep-Nov) despite similar temperatures. The temperature model predicted emissions during the cooling phase well, but overpredicted emissions during the warming phase, indicating other limiting factors for microbial CH4 production. Thus, the annual predicted CH4 emissions were about 2.3× larger than the measured values. The newly observed hysteresis effect should be considered when predicting CH4 emissions from stored manure.

First Report of Cercospora Blight of Asparagus officinalis Caused by Cercospora asparagi in New York

In October 2016, disease was observed on stems and branches of asparagus (Asparagus officinalis) in an organic crop at a fresh market farm in Ontario Co., NY. Lesions were small (<2 to 3 cm in length), generally oval and gray to tan with a reddish-brown margin. The disease was associated with defoliation on approximately 40% of plants.

Association of rumination time and health status with milk yield and composition in early-lactation dairy cows

The objective of this study was to determine the associations of rumination time (RT) and health status with milk yield and milk composition. This study used 339 dairy cows from 4 commercial dairy farms in Ontario, Canada (first lactation, n = 107; second lactation, n = 112; ≥third lactation, n = 120). Rumination time was monitored (24 h/d) using an automated system from 1 to 28 d in milk (DIM). Cows were milked 3×/d on each farm, and 2 farms recorded milk weights at each milking to determine daily milk yield (n = 170). Cows were also monitored for milk composition (fat and protein content) 1×/wk. Last, subclinical ketosis (SCK) was diagnosed 1×/wk; cows with at least one blood sample with β-hydroxybutyrate ≥1.2 mmol/L postcalving were diagnosed with SCK. Cases of retained placenta, metritis, milk fever, or mastitis during the study period were also recorded. Cows were categorized into 1 of 4 groups: healthy cows that had no SCK or any other health issue (HLT; n = 139); cows that were treated for at least one health issue other than SCK (HLT+; n = 50); SCK cows with no other health problems during transition (HYK; n = 97); or cows that had SCK and one or more other health problems (HYK+; n = 53). All data were summarized by week across cows, and the associations between rumination time and milk yield (n = 170) and milk composition (n = 339) were modeled. Across all lactations, and including all health categories, milk yield increased by week, whereas fat and protein content both decreased by week. A positive association was found between summarized RT and milk yield in first-lactation (+0.006 ± 0.003 kg/min of RT) and second-lactation (+0.015 ± 0.004 kg/min of RT) cows from 4 to 28 DIM, as well as in ≥third-lactation cows; however, the relationship between RT and milk yield differed across weeks in those cows. A negative association between RT and milk fat content was found in ≥third-lactation cows (-0.002 ± 0.00059 percentage points/min of RT). From 4 to 28 DIM, ≥third-lactation HYK and HYK+ cows produced less protein (0.11 ± 0.051 and 0.13 ± 0.056 percentage points, respectively) than HLT cows. Over the 4-wk observation period, first-lactation HYK+ cows tended to deposit 0.11 ± 0.056 percentage points less protein in their milk compared with HLT cows. Second-lactation HYK+ cows produced less milk than HLT cows each week during early lactation. In summary, RT was positively associated with milk yield in early-lactation dairy cows, across all lactations, and negatively associated with milk fat content in ≥third-lactation cows. Further, the results showed that early-lactation cows that experience SCK, particularly with one or more other health problems, might have decreased milk yield and milk protein content.

Validation of commercial luminometry swabs for total bacteria and coliform counts in colostrum-feeding equipment

A sufficient quantity and quality of colostrum must be fed quickly to the newborn calf while minimizing bacterial contamination. Adenosine triphosphate bioluminescence swabs offer a potential rapid on-farm alternative to assess bacterial contamination of colostrum. The objective of this study was to validate the Hygiena (Camarillo, CA) AquaSnap Total (AS), SuperSnap (SS), PRO-Clean (PC), and MicroSnap Coliform (MS) swabs as well as visual hygiene assessment for detection of elevated bacterial counts in or on colostrum-feeding equipment. From April to October 2016, 18 esophageal tube feeders, 49 nipple bottles, and 6 pails from 52 dairy farms in Ontario were evaluated for cleanliness. Following visual hygiene assessment, sterile physiological saline (15 mL) was poured into each piece of equipment, mixed for 2 min to ensure total surface coverage, and poured into a sterile collection container through the feeding end. The fluid was split into equal aliquots, with one being evaluated by conventional culture and the other evaluated using the luminometry swabs. Nonparametric receiver operator curves were used to compare the test performance of the luminescence reading (relative light units; RLU) from each type of swab to conventional bacterial culture. The area under the curve comparing the AS swab to total bacterial count (cut point >100,000 cfu/mL) was 0.89, and using a cut point of 631 RLU correctly classified 84% of samples with a sensitivity of 88% and a specificity of 77%. The area under the curve comparing the MS swab to total coliform count (cut point >10,000 cfu/mL) was 0.85, and using a cut point of 44 RLU correctly classified 89% of samples with a sensitivity of 83% and a specificity of 90%. Visual hygiene assessment, PC and SS swabs were not reliable indicators for feeding equipment cleanliness. The results suggest that the AS and MS swabs can be used as an alternative to traditional laboratory bacterial counts to evaluate cleanliness of colostrum-feeding equipment.

Farming in Northern Ontario: Untapped Potential for the Future

Farming in Northern Ontario is limited to less than 1% of the total land area available. With over 2000 farms, this is home to about 6% of the province’s population, concentrated in the five major southern border cities of Thunder Bay, Sault Ste. Marie, Timmins, Sudbury and North Bay, with a significant presence of indigenous (i.e., First Nations) and disadvantaged peoples. This review highlights the challenges and opportunities of agriculture in Northern Ontario and offers a few strategies for establishing and sustaining agricultural operations locally. The challenges of farming in this region include the prevalence of adverse climatic conditions, lack of crop/economic diversification, insufficient infrastructure and support services, presence of small local markets, an aging population and youth out-migration, attitudes of dependency on government and limited investment potential. Nevertheless, this region offers much potential for farming as it contains significant amounts of fertile soils, good road networks and affordable land to start up farm businesses. Furthermore, the changing climate could be a boon to improve growing conditions, with expanded cropping options and increased yields in recent years. Production and consumption of local foods, conducting innovative on-farm research that addresses the needs of local producers including First Nations peoples, fostering regional research centres, building relationships through networking, exchange of ideas through effective use of different extension avenues, and collaboration and assisting local producers with market development may help establish a more competitive and sustainable agrifood sector in Northern Ontario. Favourable government policies to support growers who have experienced damage to their crops, forages and livestock due to adverse climatic conditions will further help sustain and expand their agricultural operations.

A 3-D model to predict the temperature of liquid manure within storage tanks

A numerical model was developed to determine the year-round temperature distribution within liquid manure storages, which is relevant for modelling temperature-dependent greenhouse gas and ammonia emissions. The model considers net short and long-wave radiation, heat conduction through walls and floor, surface convective heat transfer, evaporative heat loss, and manure loading. The model was implemented and validated for a circular concrete storage tank (40 m diameter; 2.5 m depth) on a dairy farm in Ontario, Canada, where it is assumed that heat transfer occurs in horizontal and vertical directions, and is symmetric in the angular direction. Annual root mean square error (RMSE), Nash–Sutcliffe model efficiency, coefficient of determination, and average bias between model estimates and measured values were 2.4 °C, 0.91, 0.95, and 0.12 °C, respectively. The model performed best in summer and autumn (lowest RMSE), which are the most important seasons for modelling temperature, as both temperature and manure volume are highest, leading to the greatest opportunity for gaseous emissions. A sensitivity analysis indicated that the most significant parameters were solar absorptivity, manure depth, incoming manure temperature, emissivity, and wind-speed. For every unit increase in depth (m), incoming manure temperature (°C), or wind-speed (m s −1 ), the peak summer temperature changed by −7.3, 0.3, or −2.4 °C, respectively. Parameters with little effect on temperature were the manure solids content and thermal conductivity of soil around the sides and the bottom of the tank. Results show that heat transfer is primarily 1-dimensional, and a simplified 1-D model would be sufficient for future applications.

Development of the IBSAL-SimMOpt Method for the Optimization of Quality in a Corn Stover Supply Chain

Variability on the physical characteristics of feedstock has a relevant effect on the reactor’s reliability and operating cost. Most of the models developed to optimize biomass supply chains have failed to quantify the effect of biomass quality and preprocessing operations required to meet biomass specifications on overall cost and performance. The Integrated Biomass Supply Analysis and Logistics (IBSAL) model estimates the harvesting, collection, transportation, and storage cost while considering the stochastic behavior of the field-to-biorefinery supply chain. This paper proposes an IBSAL-SimMOpt (Simulation-based Multi-Objective Optimization) method for optimizing the biomass quality and costs associated with the efforts needed to meet conversion technology specifications. The method is developed in two phases. For the first phase, a SimMOpt tool that interacts with the extended IBSAL is developed. For the second phase, the baseline IBSAL model is extended so that the cost for meeting and/or penalization for failing in meeting specifications are considered. The IBSAL-SimMOpt method is designed to optimize quality characteristics of biomass, cost related to activities intended to improve the quality of feedstock, and the penalization cost. A case study based on 1916 farms in Ontario, Canada is considered for testing the proposed method. Analysis of the results demonstrates that this method is able to find a high-quality set of non-dominated solutions.

Short communication: Prevalence of digital dermatitis in Canadian dairy cattle classified as high, average, or low antibody- and cell-mediated immune responders

Lameness is a major animal welfare issue affecting Canadian dairy producers, and it can lead to production, reproduction, and health problems in dairy cattle herds. Although several different lesions affect dairy cattle hooves, studies show that digital dermatitis is the most common lesion identified in Canadian dairy herds. It has also been shown that dairy cattle classified as having high immune response (IR) have lower incidence of disease compared with those animals with average and low IR; therefore, it has been hypothesized that IR plays a role in preventing infectious hoof lesions. The objective of this study was to compare the prevalence of digital dermatitis in Canadian dairy cattle that were classified for antibody-mediated (AMIR) and cell-mediated (CMIR) immune response. Cattle (n = 329) from 5 commercial dairy farms in Ontario were evaluated for IR using a patented test protocol that captures both AMIR and CMIR. Individuals were classified as high, average, or low responders based on standardized residuals for AMIR and CMIR. Residuals were calculated using a general linear model that included the effects of herd, parity, stage of lactation, and stage of pregnancy. Hoof health data were collected from 2011 to 2013 by the farm's hoof trimmer using Hoof Supervisor software (KS Dairy Consulting Inc., Dresser, WI). All trim events were included for each animal, and lesions were assessed as a binary trait at each trim event. Hoof health data were analyzed using a mixed model that included the effects of herd, stage of lactation (at trim date), parity (at trim date), IR category (high, average, and low), and the random effect of animal. All data were presented as prevalence within IR category. Results showed that cows with high AMIR had significantly lower prevalence of digital dermatitis than cattle with average and low AMIR. No significant difference in prevalence of digital dermatitis was observed between high, average, and low CMIR cows. These results indicate that having more robust AMIR is associated with lower prevalence of digital dermatitis hoof lesions.

Vegetative Composition, Arbuscular Mycorrhizal Fungi Root Colonization, and Biological Nitrogen Fixation Distinguish Organic and Conventional Perennial Forage Systems

Core Ideas Conventional and organic forage fields did not differ in total forage yield. Legume content was more than two times greater under organic management. Total forage biological nitrogen fixation was greater under organic management. Arbuscular mycorrhizal fungi root colonization was greater under organic management. Arbuscular mycorrhizal fungi root colonization was inversely related to soil test P concentrations. Low concentrations of Olsen soil test phosphorus (STP) on organic dairy farms in Canada have been reported, however, the resulting impact on crop productivity is unclear. This study evaluated mixed forage (alfalfa [Medicago sativa L.]/timothy [Phleum pratense L.]) productivity, nutrient uptake, and related soil biological and biochemical properties on organic and conventional dairy farms in Ontario, Canada. Despite a lower STP concentration, mean organic forage yield (8.0 Mg DM ha−1) did not significantly differ from conventional (9.5 Mg DM ha−1). The proportion of N derived from biological nitrogen fixation (BNF) in alfalfa did not differ by management system, however the total forage BNF‐N was greater in the organic fields due to a twofold increase in legume proportions. Alfalfa tissue P concentrations, above the suggested critical value of 2.0 g kg−1 in all systems, were positively correlated with STP (r = 0.82, P = &lt; 0.0001) and significantly greater in conventional (3.3 g kg−1) than organic (2.4 g kg−1). Mean arbuscular mycorrhizal fungi (AMF) root colonization of alfalfa was greater in organic systems (37 vs. 23%) and was negatively correlated with STP (P = 0.0006). Management systems did not differ in soil alkaline and acid phosphatase activity, or phytase‐labile P. It was concluded that legume‐based forages can produce acceptable yields at low STP concentrations (&lt;10 mg kg−1) and supports the importance of legumes, legume BNF, and biological processes linked to soil P cycling in maintaining productivity in organic dairy farming systems.

On the Edge, at the Centre: A Life in History

Raised on a farm in southern Ontario, Gerald Hallowell attended the University of Toronto and Carleton University, where he acquired a taste for Canadian history. During a long career as an editor at the University of Toronto Press, interrupted by a few detours, he worked with authors to bring forward for publication several hundred books in the fields of Canadian history and literature. He maintained contact with potential authors by visiting universities and attending conferences across Canada and abroad, by sitting on various boards and belonging to associations, and he made difficult decisions about the publication of the results of research by historians and literary scholars. In this editorial role he was at the centre of scholarly publishing and academic life. As general editor of The Oxford Companion to Canadian History in his retirement, he was also at the centre of a large national enterprise. However, as someone who worked professionally in the field of history but did not teach in a history department as a university professor, he was also situated, quite satisfactorily in fact, on the edge of university life. These days he is researching and writing books about the town and county in which he lives, on the edge, in Nova Scotia.

Comparison of targeted selective and whole flock treatment of periparturient ewes for controlling Haemonchus sp. on sheep farms in Ontario, Canada

Haemonchosis is commonly associated with late gestation and parturition in ewes during the spring in Ontario, Canada. Due to widespread anthelmintic resistance, targeted selective treatment (TST) of ewes with closantel, an anthelmintic not previously available in Canada, at lambing was investigated as a potential strategy to manage haemonchosis in both ewes and lambs, while also maintaining parasite refugia (i.e., a population of parasites not exposed to anthelmintic). In a longitudinal pilot study in 2013 and 2014, six client-owned farms were randomly assigned as either whole treatment (WT) farms (n=3), where all the ewes were treated with oral closantel (10mg/kg) at lambing, or TST farms (n=3), where ewes were treated with oral closantel (10mg/kg) at lambing only if they met at least one of four criteria: a) the last grazing season was their first grazing season; b) body condition score ≤2; c) FAMACHA© score ≥4; and/or d) three or more nursing lambs. Pasture samples to assess larval burdens and fecal samples from a minimum of 20 ewes and 20 lambs on every farm were collected monthly during the grazing season (May-October). Additional anthelmintic treatments given by producers (either fenbendazole or ivermectin) and deaths attributable to parasitism were also recorded. Pre-treatment arithmetic mean Haemonchus sp. fecal egg counts (FECs) on each farm at the beginning of the study in May 2013, ranged from 506 to 2738 eggs per gram of feces. The number of animals treated on TST farms was reduced by as much as 47% compared to WT farms, and there was no significant difference between TST and WT farms in the proportion of additional treatments given by producers throughout the grazing season or the percentage of parasitism deaths reported. In the first year of the study, Haemonchus sp. larval burdens on pasture were generally higher on TST than WT farms at the beginning of the grazing season, but were not significantly different at the end of the grazing season. In the second year, there were no significant differences in Haemonchus sp. larval burdens on pasture between TST and WT farms throughout the grazing season. This study suggests that, under Ontario conditions, when TST indicators are able to accurately identify animals with high Haemonchus sp. FECs, TST of ewes at lambing can be employed to control Haemonchus sp. FEC in the flock, thereby maintaining refugia and delaying the onset of anthelmintic resistance.

Supporting Local Food in Northern Ontario

In attempting to understand the challenges faced by Northern Ontario with regards to locally produced food, this research is focusing on inventorying the existing production and distribution services available to farmers in Northern Ontario. Working with several Northern Ontario organizations including RAIN (Rural Agri-Innovation Network), NOFIA (Northern Ontario Farm Innovation Alliance), Northern Producer Animal Health Network, OFA and OMAFRA, a directory of these services ranging from production level services (veterinarians, crop advisors) to value added services (dairies, creameries) to distribution and retail services will be compiled to both identify where gaps in services exist and to also inform existing and potential Northern Ontario farmers of the existing services available to them. This project will attempt to link not only producers and distributors but also various communities through a networked approach. It will also identify systems currently in place to produce and distribute food and will identify best practices for increasing access to local food.

First Records of Culicoides sonorensis (Diptera: Ceratopogonidae), a Known Vector of Bluetongue Virus, in Southern Ontario.

Ceratopogonidae (Diptera) were collected on sheep farms in southern Ontario to establish whether Culicoides spp. pose a threat to the livestock industry. Specimens were collected in modified CO2-baited Centers for Disease Control and Prevention light traps, returned to the laboratory, freeze-killed, and identified to species under a microscope. In addition to Culicoides variipennis (Coquillet), we found that Culicoides sonorensis Wirth & Jones occurred on a number of farms over a 2-yr period. These records represent a significant departure from C. sonorensis' previously known geographical distribution. We present spatial and temporal distribution data for both species, with an emphasis on C. sonorensis. DNA sequence information is presented so that researchers lacking the necessary taxonomic skills can determine whether C. sonorensis is present in their collections. To differentiate C. sonorensis from C. variipennis, taxonomically reliable and informative traits were found in EF1α and, to a lesser extent, in ITS1, whereas the universal barcode region of cytochrome oxidase subunit 1 (CO1) was unsuitable.

Microbially-mediated P fluxes in calcareous soils as a function of water-extractable phosphate

Soil phosphorus (P) tests are designed to indicate plant-available inorganic orthophosphate (Pi), but fail to account for Pi that may become available through organic phosphorus (Po) mineralization. This P source may be especially important in soils with low concentrations of solution and labile Pi. We assessed gross Po mineralization and immobilization using labeling with 33P in four calcareous Alfisols with varying concentrations of Olsen soil test P that were collected from forage fields of dairy farms in Ontario, Canada. Rapid microbial 33P uptake during incubation was found for the soils with the lowest available Pi as indicated by both Olsen soil test P and water-extractable Pi. The tracer incorporation into microbial P after 8 days ranged from 7 to 44% of applied 33P and was negatively related to water-extractable Pi following a power-type relationship. As concentrations of microbial P were similar in all soils, this suggests faster turnover of P in the microbial biomass at water-extractable Pi below 0.1 mg P kg−1 soil. Daily gross Po mineralization rates ranged from 0.2 to 2.8 mg P kg−1 soil d−1 and contributed 7–56% of the isotopically-exchangeable P in 8 days. Based on these findings, microbial processes have the potential to make a significant contribution to forage P nutrition.

A comparative life cycle assessment highlighting the trade-offs of a liquid manure separator-composter in a Canadian dairy farm system

Greenhouse gas (GHG) emissions from enteric and manure management (MM) activities tend to dominate the carbon footprint of beef and milk production. In this study, a comparative life cycle assessment of dairy milk production (cradle-to-farm gate) was undertaken where the trade-offs of an automated composter-separator technology were contrasted to those of a conventional liquid manure storage system. A simulation of a dairy farm in Ontario, Canada was carried out using the process based manure-DeNitrification DeComposition (Manure-DNDC) model after it was calibrated to a comprehensive set of on-farm MM GHG emission measurements. Results indicated that the active composter system on this farm reduced the carbon footprint (CF) of milk production by 36% (from 1.92 to 1.23 kg CO2eq kg−1 fat-protein corrected milk). For the simulated dairy farm system with only liquid manure storage as a treatment option, the GHG emissions (mainly methane) from the manure storage tank contributed 56% of the carbon footprint, which surpassed the contribution from enteric methane emissions. On the other hand, for the dairy farm with the active composter system, GHG emissions from manure (34% of CF) and enteric emissions (31% of CF) were found to be nearly equivalent in terms of carbon footprint contribution. The composter system created other life cycle benefits (no need to import sand for bedding, increased soil carbon sequestration) and burdens (increased on-farm electricity demand for composter operation), however, the relative contributions of these additional trade-offs were small. Given these additional trade-offs were minor, the GHG mitigation potential of this manure composting technology is likely high in any region of application. In addition, the dairy system with the composter created only marginal problem shifting concerns in terms of the non-CF environmental impact categories considered. For the 146 lactating dairy cow system investigated, an estimated 1460 tCO2eq in life-cycle GHG emissions reduction can be achieved on an annual basis. The benefits of manure composter solutions should provide an impetus for jurisdictions to explore the development of climate policies that incentivize increased adoption rates of this important climate change mitigation opportunity.

Mortality risk factors for calves entering a multi-location white veal farm in Ontario, Canada.

Mortality in preweaned dairy-breed calves, whether they are replacement dairy heifers, veal animals, or dairy beef animals, represents both a welfare issue and a source of economic loss for the industries involved. Studies describing morbidity and mortality in veal calves have illustrated different management practices and requirements in terms of housing and nutrition around the world. Studies examining the rearing of replacement dairy heifers have shown that rates of morbidity and mortality can vary dramatically between farms, perhaps reflecting differences in management strategies. It has been over 2 decades since morbidity and mortality in veal calves in Ontario were described. The objective of this retrospective population cohort study was to describe mortality and determine whether on-arrival information could be used to predict mortality risk. Predictors could be used to both better classify and group calves on arrival and provide feedback to suppliers about the characteristics of the highest- and lowest-risk calves. We collected data from 10,910 calves entering 7 barns of a single white veal farm, all in Ontario, from January 1 to December 31, 2014. Calves were followed until death or marketing (typically 140 to 150 d). We developed logistic regression models to determine the effects of weight on arrival, season of arrival, supplier, sex, barn, and purchase price on the risk of total mortality, early mortality (0-21d after arrival), and late mortality (>21d after arrival). We identified significant associations between season, barn, supplier, weight, and total mortality risk, with lighter-weight calves arriving in winter being at increased risk. Early mortality was significantly associated with weight, season, barn, and supplier, and tended to be associated with standardized price; lighter-weight calves arriving in winter at lower prices were at increased risk. Late mortality was significantly associated with season of arrival, barn, and supplier. On-arrival measures better predicted early mortality compared with late or total mortality. A further exploration of risk factors from the dairy farm of origin for veal calf mortality would serve to improve the productivity and welfare of calves of both sexes born on dairy farms.

0120 Mortality risk factors for calves entering a multilocation white veal farm in Ontario

0120 Mortality risk factors for calves entering a multilocation white veal farm in Ontario

Identification of effective treatment criteria for use in targeted selective treatment programs to control haemonchosis in periparturient ewes in Ontario, Canada

Haemonchosis is often associated with late gestation and parturition in ewes in Canada. Due to widespread concerns about development of anthelmintic resistance (AR), targeted selective treatment (TST), where individual animals are treated with an anthelmintic rather than the entire flock, is a possible strategy to control clinical signs in recently lambed ewes while still maintaining parasite refugia. Performing fecal egg counts (FEC) on individual animals is often cost-prohibitive, so indicators that identify ewes with high FEC are essential for TST programs. The study objectives were to: a) evaluate the ability of four TST indicators to identify periparturient ewes with high Haemonchus sp. FEC and b) determine appropriate treatment thresholds for statistically-significant indicators. A field study was conducted during the 2013 and 2014 lambing seasons (February-May) on three client-owned farms in Ontario with documented AR and problems with haemonchosis in ewes. Ewes were examined within three days of lambing and selected for treatment with oral closantel (10mg/kg body weight), a novel anthelmintic to Canada, if they met at least one of four criteria: a) the last grazing season was their first grazing season; b) body condition score ≤2; c) Faffa Malan Chart (FAMACHA©) score ≥3; and/or d) three or more nursing lambs. Fecal samples were collected per rectum on the treatment day from each of 20 randomly selected treated and untreated ewes on each farm. Haemonchus sp. percentages on each farm, as determined by coproculture, ranged from 53% to 92% of total fecal trichostrongyle-type egg counts. Mean Haemonchus sp. FECs were significantly higher in treated ewes (n=136) than in untreated ewes (n=103) on the day of treatment in both years (p=0.001), suggesting the indicators were suitable for identifying animals with high Haemonchus sp. FEC. A linear mixed model was fit with logarithmic-transformed Haemonchus sp. FEC as the outcome variable, the four indicators and year as fixed effects, and farm as a random effect. FAMACHA© score was the sole indicator to remain significantly associated with FEC (p=0.002). A receiver-operator curve determined that test sensitivity was maximized (92.4%) with FAMACHA© score ≥3 as the sole indicator. FAMACHA© score should therefore be included in TST programs to identify ewes requiring treatment at lambing due to Haemonchus sp.