Alberta Cattle Research Articles

Draft Genome Sequences of 12 Histophilus somni Strains Isolated from Feedlot Cattle in Alberta, Canada.

Histophilus somni is a Gram-negative opportunistic pathogen associated with respiratory disease in cattle. Here, we report the draft genome sequences of 12 Histophilus somni strains isolated from feedlot cattle in Alberta, Canada, which were diagnosed with respiratory disease.

Integrative Conjugative Element ICEHs1 Encodes for Antimicrobial Resistance and Metal Tolerance in Histophilus somni.

The objectives of this study were to determine antimicrobial resistance and metal tolerance, and identify associated genes and mobile genetic elements in clinical strains of Histophilus somni isolated from feedlot cattle in Alberta during years 2012–2016 (contemporary isolates, n = 63) and years 1980–1990 (historical isolates, n = 31). Comparison of antimicrobial resistance (AMR) showed a significant increase in resistance among contemporary isolates compared to historical isolates (P < 0.001). Tolerance to copper (Cu) and zinc (Zn) concentrations above 1 mM was observed in 68 and 52% of the contemporary isolates, respectively. The tet(H) gene associated with oxytetracycline resistance and multicopper oxidase (mco) and cation efflux (czcD) genes associated with Cu and Zn tolerance were identified. An integrative conjugative element; ICEHs1, was identified in whole genome sequences of strains resistant to oxytetracycline, which had Cu and Zn minimum inhibitory concentrations (MIC) >1 mM. The length of ICEHs1 was 64,932 bp and it contained 83 genes, including tetracycline resistance gene tetH, a multidrug efflux pump gene ebrB, and metal tolerance genes mco, czcD, and acr3. Comparative genomics of ICEs revealed that ICEHs1 shares high homology with previously described ICEs of Histophilus somni, Pasteurella multocida, and Mannheimia haemolytica. The ICEHs1 is an active element capable of intra- and inter-genus transfer as demonstrated by successful transfer to H. somni and P. multocida recipients. All isolates carrying ICEHs1 were resistant to tetracycline, a commonly used antibiotic in feedlots, and had Cu and Zn MIC higher than 1 mM. Since Cu and Zn are routinely used in feedlots, there is the possibility of co-selection of AMR in H. somni due to selection pressure created by Cu and Zn. Based on results of in-vitro conjugation experiments, ICEHs1 mediated transmission of antimicrobial and metal resistance genes is possible between BRD pathogens in the respiratory tract, potentially undermining treatment options available for histophilosis and BRD.

Injectable antimicrobials in commercial feedlot cattle and their effect on the nasopharyngeal microbiota and antimicrobial resistance

Beef cattle in North America that are deemed to be at high risk of developing bovine respiratory disease (BRD) are frequently administered a metaphylactic antibiotic injection to control the disease. Cattle may also receive in-feed antimicrobials to prevent specific diseases and ionophores to improve growth and feed efficiency. Presently, attempts to evaluate the effects that these medications have on antibiotic resistance in the bovine nasopharyngeal microbiota have been focused on culturable bacteria that are associated with BRD. Therefore, we assessed the effects of injectable antibiotics on the nasopharyngeal microbiota of commercial feedlot cattle in Alberta, Canada, through the first 60 d on feed. Although all cattle in the study were also receiving in-feed chlortetracycline and monensin, the administration of a single injection of either oxytetracycline or tulathromycin at feedlot placement altered the nasopharyngeal microbiota in comparison with the cattle receiving only in-feed antibiotics. Oxytetracycline significantly (P < 0.05) reduced the relative abundance of Mannheimia spp. from feedlot entry to exit (≥60 d) and both oxytetracycline and tulathromycin treated cattle had a significantly lower relative abundance of Mycoplasma spp. at feedlot exit compared with the in-feed antibiotic only group. The proportion of the tetracycline resistance gene tet(H) was significantly increased following oxytetracycline injection (P < 0.05). Oxytetracycline also reduced both the number of OTUs and the Shannon diversity index in the nasopharyngeal microbiota (P < 0.05). These results demonstrate that in feedlot cattle receiving subtherapeutic in-feed antimicrobials, the administration of a single injection of either oxytetracycline or tulathromycin resulted in measurable changes to the nasopharyngeal microbiota during the first 60 d following feedlot placement.

Price Volatility Spillovers in the Western Canadian Feed Barley, U.S. Corn, and Alberta Cattle Markets

AbstractPrice volatility complicates price discovery and creates risks for cattle producers. This paper analyzes volatility spillovers in the western Canadian beef cattle supply chain. A modified bivariate VAR‐BEKK‐GARCH model is used to examine spillovers and account for asymmetries associated with rising versus falling markets. The spillovers that are found are unidirectional from input to output markets. Spillovers tended to be stronger when cattle prices are depressed and feed costs are rising. Volatility transmission is also flows from feed barley to feeder cattle markets, but volatility does not flow in the opposite direction nor does it advance by more than one level in the supply chain.La volatilité des prix complique la découverte des prix et crée des risques pour les éleveurs de bétail. Cet article analyse les répercussions de la volatilité au sein de la chaîne d'approvisionnement des bovins d'élevage. Un modèle VAR‐BEKK‐GARCH modifié à deux variables sert à l'examen des répercussions et tient compte des asymétries associées aux marchés à la hausse et à la baisse. Les répercussions décelées sont unidirectionnelles du marché des intrants aux produits. Les répercussions semblent plus fortes lorsque les prix des bovins sont bas, et les coûts de fourrage à la hausse. Le transfert de la volatilité se fait aussi sentir de l'orge de fourrage aux marchés de bovins d'engraissement, mais l'inverse ne survient pas et elle ne progresse pas de plus d'un niveau dans la chaîne d'approvisionnement.

Evaluating Alberta cattle feeders’ loan guarantee program

Purpose – The purpose of this paper is to evaluate Alberta’s cattle loan guarantee program. It measures the risk premiums on lending that would accrue to banks participating in the program, estimates the value (price) of the loan guarantee, and estimates the interest subsidy provided by the program. Design/methodology/approach – A cash flow model of cattle feeding is used. The model estimates a measure of risk that is applied to option pricing models to estimate the value of the guarantee. Findings – Insurance premiums for the credit risk to lenders are 0.20 percent of the value of the loan for the entire feeding period, and 0.41 percent for backgrounding but negligible for finishing. The price of the loan guarantee estimated by the Black-Scholes model is 4.43 percent of the value of the loan and is comparable to prices estimated by the binomial model. The program provides a subsidy rate of 4.58 percent. Research limitations/implications – Charging a guarantee fee can potentially eliminate the interest subsidy inherent in the program. But this would necessitate determining the impact of the guarantee fee on the additional access to credit that has been achieved through the program. Practical implications – Different levels of risk for backgrounding and finishing imply different risk premiums on cattle loans. Therefore interest on cattle loans should reflect not only the individual farmer’s risk profile but also the nature of the feeding operation. Originality/value – This is the first paper to simultaneously estimate risk premiums on cattle feeding loans, the value of the loan guarantee provided by the Alberta Feeder Association Loan Guarantee Program, and the inherent interest subsidy.

Prevalence and distribution of foot lesions in dairy cattle in Alberta, Canada

The objectives of this cross-sectional study were to determine the prevalence and distribution of foot lesions and associated cow- and herd-level risk factors in dairy cows in Alberta, Canada. Foot lesion data were recorded electronically by 7 hoof trimmers on 28,607 cows in 156 dairy farms from June 2009 to November 2012. Foot lesion prevalence estimates differed between farms that had the whole herd trimmed at once (≥80% of lactating cows were trimmed; n=69 farms and 8,020 cows) and farms on which part of the herd was trimmed (selection of cows was determined by farmer and <80% of lactating cows were trimmed; n=87 and 20,587 cows). Estimates were consistently higher for the latter likely because farmers presumably prioritized lame cows in partial-herd trims. On farms with whole-herd trims, digital dermatitis was the most common lesion among all housing types, present in 15% of cows and 94% of herds. Sole ulcers and white line disease were detected in 6 and 4% of the cows and 92 and 93% of herds, respectively. Other infectious and claw horn lesions each affected 1 to 2% of cows and 62 to 78% of herds. Intraclass correlation coefficients for hoof trimmers ranged from 0.01 to 0.20 for all lesions, indicating some clustering of recorded lesions by trimmer. Multilevel mixed logistic regression models were constructed (including hoof trimmer as fixed and farm as random effects) for the 3 most frequently identified lesions. Prevalence of digital dermatitis decreased with increasing parity, but this effect interacted with days in milk (DIM); primiparous cows had higher odds of digital dermatitis in mid lactation (100–199 DIM) and late lactation (≥200 DIM) compared with cows at other stages of lactation. In contrast, prevalence of sole ulcers and white line disease increased with increasing parity; compared with cows in parity 1, those in parity 4 had 5 or 7 times higher odds of having these lesions, respectively. Cows in mid lactation and late lactation had higher odds of sole ulcers and white line disease than cows at other stages of lactation, regardless of parity. Digital dermatitis prevalence was 2 times higher in herds housed in barns with access to an exercise area. The odds of sole ulcers and white line disease were ≥2 times higher in cows housed in freestalls than those housed in deep-bedded packs. Therefore, preventive measures for control of digital dermatitis merit emphasis, especially in primiparous cows and on farms with exercise areas. In addition, improving housing environment by providing a deep-bedded area for older cows in mid lactation or late lactation could reduce prevalence of claw horn lesions. We inferred that foot lesion data recorded by hoof trimmers can provide useful information not only to develop effective foot health programs at herd level, but also for disease surveillance and genetic improvement at regional and national levels.

A Focused Ethnographic Study of Alberta Cattle Veterinarians’ Decision Making about Diagnostic Laboratory Submissions and Perceptions of Surveillance Programs

The animal and public health communities need to address the challenge posed by zoonotic emerging infectious diseases. To minimize the impacts of future events, animal disease surveillance will need to enable prompt event detection and response. Diagnostic laboratory-based surveillance systems targeting domestic animals depend in large part on private veterinarians to submit samples from cases to a laboratory. In contexts where pre-diagnostic laboratory surveillance systems have been implemented, this group of veterinarians is often asked to input data. This scenario holds true in Alberta where private cattle veterinarians have been asked to participate in the Alberta Veterinary Surveillance Network-Veterinary Practice Surveillance, a platform to which pre-diagnostic disease and non-disease case data are submitted. Consequently, understanding the factors that influence these veterinarians to submit cases to a laboratory and the complex of factors that affect their participation in surveillance programs is foundational to interpreting disease patterns reported by laboratories and engaging veterinarians in surveillance. A focused ethnographic study was conducted with ten cattle veterinarians in Alberta. Individual in-depth interviews with participants were recorded and transcribed to enable thematic analysis. Laboratory submissions were biased toward outbreaks of unknown cause, cases with unusual mortality rates, and issues with potential herd-level implications. Decreasing cattle value and government support for laboratory testing have contributed to fewer submissions over time. Participants were willing participants in surveillance, though government support and collaboration were necessary. Changes in the beef industry and veterinary profession, as well as cattle producers themselves, present both challenges and opportunities in surveillance.

Benchmarking study of industry practices during commercial long haul transport of cattle in Alberta, Canada1

The objective of the present study was to document current commercial practices during long haul transport (≥400 km) of cattle in Alberta through surveys delivered to truck drivers (6,152 journeys that transported 290,362 animals). The live beef export industry to the United States (89% of all journeys) had a large influence on long haul transport. This was particularly true for fat cattle going to slaughter (82%) and backgrounded feeders going to feed yards (15%). Most drivers had either limited (31% with < 2 yr) or extensive (35% > 10 yr) experience hauling cattle. The type of tractors and trailers used most frequently were those with more number of axles (quad-axle trailers pulled with push tractors) because they can accommodate extra weight. Mean (± SD) distance travelled was 1,081 ± 343 km (maximum of 2,560 km) whereas time animals spent on truck averaged 15.9 ± 6.3 h with a maximum of 45 h. However, only 5% of all journeys were greater than 30 h. The most frequent cause of delay was at the Canada-United States border crossing due to paperwork and veterinary inspections. Border delays occurred on 77% of all journeys which had a mean of 1.3 ± 1.9 h and up to 15-h long. Driver rest stops and waiting to unload cattle at destination were the second most frequent and longest cause of delay. Ambient temperature across all journeys ranged from -42 to 45°C with a mean value of 18 ± 11.8°C while temperature variation within a journey was from 0 to 46°C with mean value of 15 ± 6.6°C. The proportion of dead, non-ambulatory, and lame cattle for all journeys was 0.011, 0.022, and 0.011%, respectively. The cattle transport industry showed compliance with federal regulations and to a lesser extent with recommendations. Findings showed extreme values and very large variability in transport conditions however further research is needed to assess their impact on animal welfare outcomes. Delays within the journey as a result of border crossing, weather conditions, time on truck, shrink and space allowance may play an important role in improving cattle welfare during long haul transport.

Escherichia coli O157:H7 lineages in healthy beef and dairy cattle and clinical human cases in Alberta, Canada.

The aim of this study was to examine the prevalence and distribution of Escherichia coli O157:H7 lineage-specific polymorphism assay (LSPA) 6 genotypes from cattle (n = 313) and clinical human (n = 203) isolates from northern and southern Alberta, Canada, to understand possible associations of genotypes with host and geographic location. The majority of cattle isolates (feedlot and dairy) typed as LSPA-6 111111 (72.2%), with proportionately higher LSPA-6 222222 (19.4%) than other LSPA-6 genotypes (10.7%). Clinical human isolates also typed primarily as LSPA-6 111111 (90.1%), but a higher percentage of genotypes (6.8%) other than LSPA-6 222222 (3.1%) was observed. A significantly higher frequency of LSPA-6 111111 in southern Alberta cattle (P < 0.0001) and a significant difference in LSPA-6 genotypes between human versus feedlot cattle from northern Alberta (P < 0.0001) were detected. LSPA-6 211111 genotype was third and second most common in cattle and humans, respectively, and several new LSPA-6 genotypes (n = 19) were also discovered. Despite avoiding over-representation of isolates from specific farms or outbreaks, higher strain diversity among cattle by pulsed-field gel electrophoresis (PFGE; 50 genotypes) in contrast to human (9 PFGE genotypes) isolates was observed. The majority of cattle (74.4%) and human (90.6%) isolates were susceptible to the antimicrobials tested. Within resistant cattle isolates, sulfisoxazole-tetracycline resistance was common (62.5%) and was accounted for by the presence of sul1 and sul2, and tet(A) and tet(B) determinants. An association between LSPA-6 and PFGE genotypes but not between geographic location and PFGE genotype for both hosts was evident.

If It Ain't Alberta, It Ain't Beef

This paper examines the emergence of Alberta beef as a defining feature of Albertan identity. Contrary to dominant public discourse, cattle production and beef consumption are not natural, inevitable nor politically neutral features of Alberta's history and culture. Rather, they have been established as such by tourist marketing, industrialization and market globalization. The emergence of BSE in Alberta's cattle herd in 2003 served to galvanize the link between beef and regional identity, and also to foster a link between contradictory discourses of provincialism and nationalism.

Methane emissions from enteric fermentation in Alberta’s beef cattle population

This study determined methane emissions from enteric fermentation in Alberta’s beef cattle population by using three methodologies: (1) Intergovernmental Panel on Climate Change (IPCC), Tier 2 guidelines for cattle, (2) actual methane emission factors, expressed as a percentage of gross energy intake, from Canadian research trials and; (3) CowBytes© plus the basic equation developed by Blaxter and Clapperton (1965). Methane emissions, in carbon dioxide equivalents (CO2-E), from Alberta’s beef cattle were determined for 1990, 1996 and 2001. Census of Agriculture numbers for Alberta (Statistics Canada; www.statcan.com) were used and beef cattle were subdivided into 31 distinct categories based on animal type, physiological status, gender, weight, growth rate, activity level and age. Emission of greenhouse gases (GHG) from Alberta ’s beef cattle population, based on IPCC Tier 2 guidelines, were 4.93, 6.57 and 7.01 Mt CO2-E yr-1 in 1990, 1996 and 2001, respectively. Emissions based on methane emission factors from Canadian research trials were 6.23, 8.26 and 8.77 Mt CO2-E yr-1 in 1990, 1996 and 2001, respectively. Estimated methane emissions based on CowBytes© and Blaxter and Clapperton’s (1965) equation were 6.24, 8.35 and 8.94 Mt CO2-E yr-1 in 1990, 1996 and 2001, respectively. The IPCC Tier 2 values were 25.2–26.5% lower than the GHG emissions calculated using emission factors from western Canadian research and 26.7–27.6% lower than GHG emissions calculated from CowBytes© and Blaxter and Clapperton’s equation. IPCC Tier 1 values, which were calculated by multiplying total beef cattle in Alberta by four single value emission factors (beef cows = 72 kg CH4 yr-1; bulls = 75 kg CH4 yr-1; replacement heifers = 56 kg CH4 yr-1; calves, steer and heifer calves for slaughter = 47 kg CH4 yr-1), were 4.83, 6.40 and 6.83 Mt CO2-E in 1990, 1996 and 2001, respectively. Thus, IPCC Tier 1 GHG emissions from enteric fermentation in beef cattle were 2.0–2.7, 28.6–29.1 and 29.2–31.0% lower than those calculated from IPCC Tier 2, western Canadian research trials, and CowBytes© plus Blaxter and Clapperton’s equation, respectively. These results reflect the uncertainty associated with estimating methane emissions from enteric fermentation in cattle and suggest that further research is required to improve the accuracy of methane emissions, particularly for beef cows in their second and third trimester of pregnancy and fed in confinement. They also indicate that a more robust methodology may be to combine CowBytes© predicted dry matter intake with regional specific methane emission factors, where methane loss is expressed as a percentage of gross energy intake. Key words: Cattle, enteric fermentation, greenhouse gas, methane

Electronic Network of Veterinary Practitioners for Surveillance of Alberta's Cattle Population

Alberta Agriculture Food and Rural Development (AAFRD) is developing an electronic surveillance network to collect cattle health information from practicing veterinarians in Alberta. The network will provide cattle health information specific to the surveillance needs of the provincial cattle industry, including rapid detection of emerging and foreign animal diseases, demonstrating the presence of a well-trained effective veterinary service, and establishing freedom from diseases of importance to trade. A second goal is to provide livestock health information of value to practicing veterinanans.

Cattle and the Petroleum Industry

Veterinarians are occasionally called upon to investigate concerns from cattle producers who feel they have suffered economic losses resulting from the effects of industrial activity on the health and productivity of their livestock operation. The following is an introduction to some of the problems that can occasionally result from the close proximity of cattle to petrochemical activities. Some strategies for investigating these types of problems are also suggested. Peer-reviewed experimental or observational field studies of the effects of the petroleum industry on livestock are very limited. The available literature consists of scattered case reports, reviews of these case reports, a few small experimental dosing studies in cattle, experimental results extrapolated from other species, and observational reports from the "gray literature" of conference proceedings and environmental accidents or complaint investigations.&#x0D; This paper is intended as a brief introduction for the practicing veterinarian called to investigate petroleum related complaints. It is not intended to be an exhaustive review of the available material. A more detailed presentation of the potential hazards to livestock from the oil and gas industry has recently been released by the Alberta Cattle Commission.1

Relevance of National Research Council feed composition tables in Alberta

The nutrient concentrations of selected Alberta-grown whole barley grain (Hordeum vulgare L.), three pure hays of alfalfa (Medicago sativa L.), barley, oat (Avea sativa L.), and four pure crop silages of alfalfa, barley, corn (Zea mays L.), and oat were determined and compared with nutrient concentrations of similar forages and a cereal grain reported in the National Research Council (NRC 1984 and 1989) feed nutrient composition tables. In addition, the variations in nutrient concentrations within the selected Alberta feedstuffs were assessed as an indication of whether the feedstuffs should be analysed frequently for certain nutrients. The concentrations of zinc and copper in barley grain cultivated in Alberta were 248% and 60% of the NRC values, respectively. The phosphorus, manganese, sulphur, magnesium, CP, selenium and calcium concentrations in barley hay were 17, 18, 18, 22, 32, 50 and 100% higher than NRC values. However, the concentrations of Cu and Zn were only 18 and 40% of the NRC values. Data from the present study suggest that Alberta hays, silages and barley grain are different in nutrient concentrations from similar grain and forages reported by the NRC (1984, 1989). Due to a high percentage of Alberta feeds being below the suggested NRC requirement levels of the various trace minerals, use of NRC table values for Cu, Mn, Mg and Zn for barley hay, silage and grain, oat hay and silage, alfalfa hay and silage and corn silage could result in deficiencies of these trace minerals in beef and dairy cattle with possible adverse effects on productivity. Thus, there is a need to use Alberta-derived nutrient composition values for these elements in diet formulations for cattle in Alberta. The high CVs calculated for most of the nutrients in the selected Alberta feeds suggest that these feeds should be analysed more often in order to minimise costs of production due to nutrient shortfalls or excesses in diets formulated using nutrient values without the knowledge of variability in feed composition. Key words: Nutrient composition, variability, feedstuffs

PREWEANING PATTERNS OF GROWTH IN THREE BREED GROUPS OF ANGE BEEF CALVES

Preweaning weight records of 2856 spring-born calves raised at the University of Alberta cattle ranch during a 15-yr period were used in this study. Calving occurred mainly in April and May every year. Calves from three breed groups: Hereford (HE), Beef Synthetic (SY) and Beef Crossbred (XB) were weighed at birth, and in late June, July and August and at weaning in mid-October. They were classified as early, mid-season and late-born according to their birth dates. Average daily gain (ADG) between two consecutive weighings and relative growth rate (RGR) at each interval were analyzed by the least squares method and the adjusted means were plotted against the mean ages of the calves classified at 2-wk intervals to determine the pattern of changes in ADG and RGR with the increase in age of the calf. The SY calves had the highest ADG and RGR followed by the XB and HE (P &lt; 0.05). Bull calves exhibited significantly higher (P &lt; 0.05) absolute growth rate than heifer calves but the sexes were not different in RGR. Preweaning ADG reached a peak when calves were between 110 and 120 d old and declined thereafter. The decline in RGR was linear during the preweaning period. The mean growth rates of the early and mid-season calves were significantly (P &lt; 0.05) higher than that of the late-born calves, and early-born calves showed more consistent gain than the mid-season and late-born calves. A pronounced decline in gain was observed for mid-season and late-born calves in late summer when pasture condition deteriorated indicating that early weaning and supplementation of calves' diet at that stage might be beneficial in sustaining growth rate of the calves. Key words: Cattle (beef), preweaning growth, calf (beef)

COMPARISON OF SILHOUETTE, STICKY, AND SUCTION TRAPS WITH AND WITHOUT DRY-ICE BAIT FOR SAMPLING BLACK FLIES (DIPTERA: SIMULIIDAE) IN CENTRAL ALBERTA

AbstractIn 1982 and 1983, silhouette traps, sticky traps, and suction traps with and without dry-ice bait were evaluated for sampling populations of black flies that are pests of cattle in central Alberta. The dry-ice-baited silhouette trap was the most effective. The black-fly species collected were Simulium arcticum, S. aureum, S. decorum, S. meridionale, S. tuberosum, S. venustum, S. verecundum, S. vernum, and S. vittatum. Approximately 80% of the black flies collected each year were S. arcticum, the primary pest species of cattle in Alberta.

Predation Losses of Cattle in Alberta

Coyotes (Canis latrans), black bears (Ursus americanus), and wolves (Canis lupus) were reported responsible for 35, 31, and 16%, respectively, of confirmed predation losses of cattle in Alberta during 1974-78. Coyotes selected for calves over adults, and adults over yearlings, black bears selected for calves over yearlings, and yearlings over adults, and wolves selected for calves and yearlings over adults. Predation of cattle by coyotes, bears, and wolves peaked during March-June, May-July, and AugustSeptember, respectively. Little information is available on predation losses of cattle, even though the value of losses from predation are comparable for cattle and sheep in the United States (Anon. 1978, Gee 1979). In Alberta, the value of cattle lost to predation from coyotes, black bears, and wolves exceeds that of other species of livestock.' This paper describes the monthly chronology and age distribution of predation losses of cattle in Alberta, Canada during 1974-78.

Development of Cattle Grubs in Oklahoma Cattle Imported into Canada

Infested weanling heifer calves were imported into Alberta from Oklahoma in October of 1956. The subsequent seasonal incidence curve of their cattle grubs was characteristic of Oklahoma and not of Alberta infestations. Hypodermal grubs of Hypodermalineatum (de Villers) were found in these cattle earlier than in control Alberta cattle and the grubs dropped over a longer period of time. Grubs of H. bovis (L.) in the Oklahoma cattle formed a discrete second peak in the seasonal incidence curve. They occurred in the backs and dropped out at the same time as those in the Alberta cattle. Results of artificial infestations of Alberta cattle with H. lineatum eggs of Oklahoma origin indicated that the rate of development or grubs was not influenced by atmospheric temperatures. Published autecological results and soil temperature records suggested that only a small number or late-season Oklahoma puparia of H. lineatum would survive in Alberta, but that H. bovis would surive as well as the native ones. It is suggested that when northern cattle are imported into Oklahoma the relatively high temperatures would accelerate development of puparia, so their offspring would appear progressively earlier in subsequent years This would be particularly noticeable for H. bovis infestations. A group of late-born Oklahoma calves, imported into Alberta in 1961, carried grubs of H. bovis, which occurred in the backs earlier in the season than in the cattle examined in 1956-57. Apparently adaptation to the Oklahoma seasons had taken place in the intervening 5 years. H. bovis seems to be establishing itself in Oklahoma and adjusting to the seasons through adaptation in the puparial stage.