A total of 4,778 cows from 179 herds were tested for antibodies to N. caninum using a commercially availableELISA. Neospora caninum herd-level seroprevalence ranged from 25.0% to 75.9% (a herd was considered positive with ¡Ý 2 cows testing positive). The true cow prevalence was estimated as 5.2% (95% CI= 4.6 ¨C 5.8). ¡°Pre-calving use of dry lots¡±, ¡°separation of cow-calf pair from other cows after calving¡±, ¡°use of standing water in summer¡±, ¡°use of running water in winter¡±, ¡°feeding heifers with manure handling equipment¡±, ¡°abortion and stillbirths left for canids¡± and ¡°number of sightings of wild canids per year¡± (categorized into three categories: less than 10 times per year, 11¨C 25 times per year, and greater than 26 times per year) were positivelyassociated with herd serological status.
However, ¡°washing boots between visits to livestock farms¡± was negatively associated with serological status. These 8 variables were included in a multivariable logistic regression model. Province and herd size were considered potential confounders and kept in the model regardless of significance. Only 4 variables remained significant in the final model.Risk factors associated with prevalence included the use of dry lots/corrals as pre-calving area (OR=2.8; 95% CI =1.3 ¨C 6.2), the use of natural standing water in summer (OR=3.2; 95%CI=1.31 ¨C 8.0), and leaving abortions/stillbirths for dogs or wild canids (OR=2.5; 95%CI=1.0 ¨C 5.9).
As the frequency of sighting coyotes and foxes increased so did herd seroprevalence to N. caninum. Risk factors suggested the likely role of horizontal transmission in the transmission of N. caninum in these beef cow-calf herds. Beef herd managers might consider biosecurity practices such as preventing the access of wild canids to fetuses and stillbirths thereby preventing pasture contamination and controlling contamination of water source with oocyst of N. caninum thereby reducing chances of infection.
Aherd was considered positive for Bovine leukemia virus (BLV) if ¡Ý 1 animal tested positive.Estimates of cow-level seroprevalence was 1.01% (95% CI= 0.73% ¨C 1.29%) while herd seroprevalence was 12.4% (95% CI= 7.57 ¨C 17.23). Potential risk factors examined for BLV transmission included the use of blade or surgical castration without disinfection between animals, using gouger and saw dehorning methods, multi-use of common rectal sleeve between cows without disinfection and the use of communal pasture where mating occurred.
No associations existed between potential risk factors and seropositivity to BLV because the number of herds testing positive to BLV were too few to find any association. However, management practices observed in this study may have the potential to transmit infections.
Lapses in biosecurity practices identified were addition of new animals to the herds(73.7%, 132/179), the use of communal grazing (24.0% (43/179) of herds using with 28% (12/43) using more than one communal pasture where mating occurred(93%, 40/43) with bulls from other herds. During communal grazing, contact herds ranged between 1 and 25 (mean = 7.4). Large herds (¡Ý111) animals were more likely to use communal pasture compared to medium sized or small herds (¡Ü46) (P<0.01).
Domestic and wild canids had access to stored grain in 19% (34/179) of herds. The odds of wildlife gaining access to stored gain is twice as high (OR=2.37, P<0.02) in western Canada compared to eastern Canada.
Purebred herds were less likely to be fed on the ground compared to cross-bred herds (P<0.03). Herds from western Canada administered more feedstuffs on the ground compared to herds from eastern Canada (P<0.01). Large herds were more likely to store feedstuffs outdoors compared to small herds (P<0.01). Herds from western Canada were more likely to store their feedstuffs outside compared to herds from eastern Canada (P<0.01).
The odds of not removing surface manure from maternity pens was almost three times (OR=2.98, P<0.01) in herds from western Canada compared to eastern Canada. 78.7% (140/179) of herds disposed ofmanure by spreading on surface ground. 52% (93/179) of herds borrowed manure contaminated equipment from other producers for use on their farms.
Thirty three percent (53/179) of herds performed breeding soundness examinations in breeding bulls and 9.5% (17/179) of herds performed trichomonas testing on breeding bulls. Large herds were more likely to co-mingle cows and heifers during the breeding season (P<0.01) compared to small herds. Cow-calf pair separation from other cows after calving occurred more in large herds compared to medium sized or small herds (P<0.01). The odds of using maternity pen as hospital pen was twice in western compared to the eastern Canada (OR=2, P=0.04).
Sixty percent (107/179) of herds used the same area for calving and winter-feeding. Herds from western Canada were more likely to use the same area for calving and winter feeding compared to herds from eastern Canada (P<0.01). Forty-one percent (73/179) of herds used hospital pens as maternity pens during calving season. 35.8% (64/179) of herds transported animals to veterinary clinic for treatment. In nine percent (16/179) of herds visitors or outside employees changed their boots, and in18% (32/179) visitors washed their boots.
Eighty two percent (146/179) of herds dehorned cattle, of which 74% (109/148) used non-bloodless methods. Of herds using non-bloodless dehorning methods, 28.4% (31/109) disinfected dehorning equipment between animals. 73.7% (132/179) of herds reported castrating animals, of which 32.6% (43/132) used surgical castration method.
Of herds using surgical castration method, 81.4% (35/43) disinfected surgical equipment between animals. 12.2% (22/179) of herds disinfected or used new needles between animals when injecting drugs or vaccines. Thirty five percent (63/179) of herds changed sleeves between animals when performing rectal examinations.Over twenty nine percent (29.6%, 53/179) of herds left abortions for dogs and coyotes while 27.4% (49/179) of herds left stillbirths for dogs and coyotes.The risk of adding calves persistently infected (PI) with Bovine Viral Diarrhea (BVD) virus exists with 13% (23/179) of herds adding unweaned beef calves and 18.4% (33/179) adding weaned beef calves without pre-purchase testing.PI calves are known for shedding large amounts of BVD virus and spreading BVD virus infection in beef herds.
BVD virus vaccination may compensate for exposure to the virus in a cowherd by mitigating the risk of fetalinfection; however, the timing of vaccination is essential to offer protective immunity. BVD virus vaccine administered during pregnancy check may not protect the fetus against BVDV infection.There is likelihood of infection in-utero resulting in immunotolerant fetus persistently infected (PI) with BVDV and carried to term. This may occur if calf was infected in-utero before 125 days of gestation. Herds in this study administered BVD virus vaccination to breeding cows prior to breeding (60%, 118/179), during pregnancy check (28%, 50/179), and at other times (6%, 11/179).
In replacement heifers, BVD vaccination was administered prior to breeding (79%, 142/179), during pregnancy check (13.4%, 24/179), and at other times (7.3%, 13/179).Herds vaccinating breeding cows for BVD virus were 63.1% (113/179), of which 29.1% (52/179) used modified live vaccine and 34.1% (61/179) used killed vaccine. Herds vaccinating replacement heifers for BVD were sixty percent (107/179), of which 25.1% (45/179) used modified live virus vaccine and 34.6% (62/179) used killed vaccine.
The role ofthe veterinarianis essential in educating producers on what constitute risky practices and how to mitigate such risks. Approach to mitigating risks may not necessarily be the same for all cow-calf herds; it must be tailored to each production unit. Initial risk assessment will identify what constitutes risky management practices, after which sound mitigation measure are designed to address such risks. On-farm biosecurity practices needs approach within the framework of risk assessment and periodic review for effectiveness.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-03232011-150559 |
| Date | 14 April 2011 |
| Creators | Olaloku, Olaniyi Agboola |
| Contributors | Campbell, John, Haines, Debbie, Misra, Vikram |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-03232011-150559/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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