Randomized control trial to investigate compliance with, and impacts of, cow comfort recommendations on smallholder dairy farms in Kenya.

Smallholder dairy farmers (SDF) in developing countries often have limited understanding on the importance of cow comfort. We conducted a randomized controlled trial with 124 cows on 114 Kenyan SDF to determine the status of cow comfort, to assess compliance to farm-specific cow comfort recommendations, and to evaluate the impacts of the farm-specific interventions on cow comfort. On the first farm visit, stall dimensions and characteristics (e.g. stall base hardness and hygiene) were measured and categorized as adequate, marginal or inadequate/absent based on cow size. Where measurements were not adequate, farm-specific cow comfort recommendations were provided in written and oral form to the randomly allocated intervention group of farms (n = 74). On the second farm visit two months later, the same measurements were taken, and percent compliance to the recommendations was evaluated. A discomfort index was arithmetically calculated based on the stall base hardness (scale was 1-3 for soft to hard) and hygiene (scale was 1-5 for clean to dirty). Multivariable linear regression models were used to determine specific associations with the discomfort index. On the first visit, the mean stall base hardness and stall hygiene scores were 1.7 and 2.3, respectively, for a mean discomfort index of 4.0. Intervention farmers were given 3.9 comfort recommendations, on average, and complied with 2.1 recommendations, significantly improving the discomfort index at visit two to 3.3. The overall compliance to the recommendations was 49.0%. In a final model, the interaction between intervention group and visit number was significantly associated with discomfort index, indicating that after adjusting for baseline discomfort indices, the intervention led to better cow comfort. Specifically, bedding type and neck rail positioning were significantly associated with discomfort index. We concluded that farmers can substantially improve cow comfort on SDF by providing recommendations to them. Farm advisors should include cow comfort recommendations to SDF.

Evaluation of environmental and comfort improvements on affective welfare in heifer calves on smallholder dairy farms.

A controlled trial on zero-grazed smallholder dairy farms was conducted to determine the effect of environmental and comfort improvements on sucking and lying behaviours in heifer calves on Kenyan smallholder dairy farms. The study involved 187 heifer calves from 150 farms in two Kenyan counties, 75 farms per county. Farms in one county received animal welfare training and improvements in the calf pen that included: 1) placement of rubber mats on the lying area; 2) fixing gaps/holes in the flooring and roofing; and 3) attaching a rubber nipple on the wall of the calf pen. During the 16-month data collection period, bimonthly farm visits were used to collect data on lying time (using accelerometers) and other animal- and farm-level factors. Multilevel mixed-effects linear regression was used to model daily lying times and frequency of lying bouts, with the animal as a random effect. Over the visits, daily lying times and lying bout durations averaged 12.6-86.7 min/bout, respectively, while the median for the frequency of lying bouts was between 30-46/day. Provision of rubber nipples for non-nutritive sucking lowered proportions of cross-sucking, self-sucking and object-sucking behaviours slightly but not significantly. In a final daily lying time model, superficial lymph node enlargement, body condition score and use of wood shaving/ sawdust/ crop waste as beddings had positive associations. In contrast, group housing and rubber mat use had negative associations with daily lying time. In an interaction term, lying time was significantly higher for calves on clean versus dirty floors if the age was <190 days but this difference diminished significantly in older animals. In a second interaction term, lying time was lower for calves with leaking versus non-leaking roofs, regardless of the pen floor level, but lying time was higher on elevated than non-elevated floors if the roof was intact. In the final model of the frequency of lying bouts, the use of a rubber mat, the years of experience in dairy farming, and calf body weight had negative associations. In contrast, body condition score had a positive association. In an interaction, the frequency of daily lying bouts was lower on clean floors than dirty floors, irrespective of tethering status, but when the floor was dirty, the lying bouts were higher for animals not tethered than the ones sometimes tethered. We conclude that the comfort improvements enhanced the welfare and lying experience of heifer calves on smallholder dairy farms.

Management factors associated with time-to-onset and fecal egg/oocyst counts of gastrointestinal parasites in heifer calves on Kenyan smallholder farms.

A prospective cohort study on zero-grazed smallholder dairy farms was conducted to determine factors associated with onset and counts of gastrointestinal parasitism in heifer calves. The researchers recruited 187 newborn heifer calves from 150 farms in Kenya. Over 16 months, farm visits every two months were used to collect rectal fecal samples and animal- and farm-level measures. Fecal samples underwent centrifugal fecal flotation with Sheather's sugar to determine counts of strongyle-type eggs and coccidia oocysts. Cox proportional hazard (Cox PH) analysis and mixed-effects negative binomial (MeNB) regression determined factors associated with time-to-onset and counts of strongyle-type eggs and coccidia oocysts, respectively (P < 0.05). The incidence rate of strongyles was 0.0011 cases/animal-day while coccidia was 0.0073 cases /animal-day. Incidence risks of strongyles and coccidia over the study period were 28.3 % (53/187) and 87.7 % (164/187), respectively. For infected calves, median time-to-onset for strongyles and coccidia was 78 (interquartile-range: IQR 38-117) and 43 (IQR 29-92) days, respectively. In the final Cox PH model for strongyles, breed (Ayrshires and Jerseys) and weaned calves had a greater hazard of infection than Friesians and preweaned calves, respectively. Calf tethering outside the pen was associated with a higher hazard of strongyle infection. In the final Cox PH model for coccidia, calves with watery and/or hemorrhagic diarrhea had a higher hazard compared with those with hard or soft feces. Weaning status and birth weight (kg) were time-varying covariates, leading to increased hazard over time. In the final MeNB model for strongyles, weaned animals had higher counts than those still on milk. In an interaction variable, the predicted strongyle-type egg counts increased with longer duration of farm operation when herd size was less than five cattle, but decreased when herd size was more than five. In the final MeNB model for coccidia, calves sometimes tethered outside their pens had higher counts than those continuously enclosed in the pen. Calf pen floors with either scant manure or moderate slurry had higher predicted counts than those on a clean pen floor. Calves with watery or hemorrhagic diarrhea and fed fresh Napier grass (Pennisetum purpureum) had higher counts compared with soft or hard feces and those not given fresh Napier, respectively. In an interaction variable, calves experiencing diarrhea and raised on elevated slatted floors had lower oocyst counts compared with those having diarrhea but not on elevated floors. The identified management practices associated with onset and counts of gastrointestinal parasitism should be considered in control efforts.

Evaluation of influence of milk urea nitrogen on reproductive performance in smallholder dairy farms.

OBJECTIVE: The aim of this study was to determine the relationship between milk urea nitrogen (MUN) and reproductive performance in dairy cows in western Thailand. DESIGN: All cows calving from November 2014 to April 2015 were included in the study, a total of 486 cows from 47 farms. Each cow had milk constituents and MUN tested monthly up to confirmed conception or until the 8th month after parturition. Each farm had a dietary assessment completed. Cox proportional hazard models with shared frailty were used to determine associations of conception rate. RESULTS: Cows became pregnant increasingly quickly over time, except during 100-150 days of lactation. A change in MUN from 12.5 to 13.5 mg/dL on the closet day to breeding was associated with a 5% decrease in conception. Milk protein was negatively associated with hazard of conception, whereas milk lactose and dietary protein:energy ratio had positive associations with conception rate. Breeding season was also significant; the highest conception rate was observed in cows inseminated during winter, whereas insemination during the humid rainy season resulted in the lowest conception rates. The farm random effect in the model was strongly significant. CONCLUSION: Detrimental effects of higher MUN on rate of conception were identified. The rate of conception was positively associated with protein:energy ratio in the study. Therefore, good nutritional management leading to positive energy balance should benefit conception rates.

Effects of Calliandra and Sesbania on Daily Milk Production in Dairy Cows on Commercial Smallholder Farms in Kenya.

There is a growing interest in protein supplementation of dairy-cow diets using leguminous shrubs. The study objective was to ascertain the association between diet supplementation with Calliandra calothyrsus and Sesbania sesban and milk production in dairy cattle on commercial smallholder farms. This trial involved 235 cows from 80 smallholder dairy farms in Kenya randomly allocated to 4 intervention groups: (1) receiving Calliandra and Sesbania and nutritional advice; (2) receiving reproductive medicines and advice; (3) receiving both group 1 and 2 interventions; and (4) receiving neither intervention. Farm nutritional practices and management data were collected in a questionnaire, and subsequent physical examinations, mastitis tests, and milk production of cows on the farm were monitored approximately monthly for 16 months. Descriptive and univariable statistical analyses were conducted, and multivariable mixed-model regression was used for identification of factors associated (P < 0.05) with daily milk production. The mean milk production was 6.39 liters/cow/day (SD = 3.5). Feeding Calliandra/Sesbania to cows was associated (P < 0.0005) with an increase in milk produced by at least 1 liter/cow/day with each kg fed. Other variables positively associated with ln daily milk production in the final model included feeding of Napier grass, amount of silage and dairy meal fed, body condition score, and appetite of the cow. Other variables negatively associated with ln daily milk production in the final model included amount of maize germ fed, days in milk, sudden feed changes, pregnancy, and subclinical mastitis. In conclusion, our field trial data suggest that use of Calliandra/Sesbania through agroforestry can improve milk production in commercial smallholder dairy farms in Kenya. Agroforestry land use systems can be adopted as a way for dairy farmers to cope with feed shortages and low crude protein in farm-available feeds for their cows.

Effects of Calliandra and Sesbania supplementation on weight gain in dairy calves on smallholder farms in Kenya.

The growth rate of female calves on dairy farms is one of the crucial factors which influence age at first calving, affecting lifetime lactation productivity of a dairy cow. Diets with adequate crude protein are necessary to support calf growth. The study objective was to determine the effects of nutritional advice and diet supplementation with Calliandra calothyrsus and Sesbania sesban on average daily weight gain in dairy calves on semi-commercial smallholder dairy farms in Kenya. This trial involved 155 calves from 73 smallholder dairy farms, in Kenya, randomly selected and allocated to either intervention or control groups. The intervention group received nutritional advice and seedlings of Calliandra calothyrsus and Sesbania sesban, while the control group did not receive these interventions. Every 1-2 months for 16 months, data on farm nutritional practices and management were collected in a questionnaire, and physical examinations were done to monitor weight and health status. Descriptive and univariable statistical analyses were conducted, and multivariable mixed linear regression models were used for identification of factors associated (P < 0.05) with the natural log transformation of weight gain of calves on a given farm, controlling for clustering of visits within calves. Feeding at least 0.2 kg/day (wet weight) of Calliandra or Sesbania to calves <6 months old resulted in 33.2% increase in daily weight gain, while controlling for confounding by breed and sex of the calf. For calves ≥6 months, there was a significant interaction between amount of hay fed and if calves were also fed on Calliandra or Sesbania. When no Calliandra or Sesbania supplementation was provided, the mean weight gain was low and relatively constant even with increasing amounts of hay. When Calliandra or Sesbania supplement was added to the diet, the mean weight gain increased from 0.17 kg to 0.48 kg when hay was fed at 1 and 5 kg, respectively, while controlling for confounding by amount of maize silage fed and the prevailing season. In conclusion, supplementation of calf diets with at least 0.2 kg/calf/day of Calliandra or Sesbania is beneficial for faster weight gains.

Risk factors associated with cows' lying time, stall and cows' own cleanliness in smallholder dairy farms in Kenya.

BACKGROUND AND AIM: The welfare of animals kept in livestock production systems has raised concerns around the world. Adult dairy cattle require adequate rest and spend approximately 12 h/day lying down. This cross-sectional study aimed to determine the stall factors and management practices affecting cows' lying time, stall cleanliness, and cows' cleanliness (udder and upper leg), in smallholder dairy cows in Meru County of Kenya. MATERIALS AND METHODS: A total of 106 milking cows from 73 farms were assessed for daily lying time and cleanliness. Data loggers were used to record the lying time of cows for 3 days. Stall, udder, and upper leg cleanliness were assessed using a 5-score system: 1 (very clean) to 5 (very dirty). Management information was acquired using a questionnaire that was administered face-to-face to the farmers in their native Kimeru language. Univariable and multivariable linear and logistic regression models were fit to determine factors associated with cows' lying time and dichotomized stall and cows' own cleanliness, respectively. RESULTS: The mean daily lying time was 10.9±2.2 h, and the mean stall cleanliness score was 2.4±1.0. The mean average cleanliness scores of the udder and upper legs were 1.9±0.7 and 2.5±1.1, respectively. Overall, 35% of the stalls were categorized as dirty (>2.5), whereas 13% and 47% of the cows had udder and leg cleanliness scores >2.5, respectively. From the final multivariable models (p<0.05), daily lying time increased by 1.0 h for cows older than 5.25 years versus younger cows. Conversely, lying time decreased by 1.0 h with stall cleanliness scores >2.5 and by 1.6 h with poorly positioned neck rails. In an interaction term, addition of new bedding at least once a day without removing stall manure at least once a day decreased the daily lying time of the cows by 1.5 h, whereas failure to add new bedding at least once a day but removing stall manure at least once a day decreased the lying time of the cows by 1.2 h. Farm-level risk factors for stall dirtiness (>2.5) included delayed cleaning of the alley (odds ratio [OR]=6.6, p=0.032), lack of bedding (OR=4.9, p=0.008), and standing idle and/or backward in the stall (OR=10.5, p=0.002). Stalls categorized as dirty (OR=2.9, p=0.041) and lack of bedding (OR=2.7, p=0.065) were cow- and farm-level risk factors for dirtiness of the udder (>2.5), respectively, whereas the stall being dirty (OR=2.3, p=0.043) was the only risk factor (cow level) for dirtiness of the upper legs (>2.5). CONCLUSION: It was recommended that farmers should pay attention to the specific factors identified regarding the stall design (e.g., neck rail position) and bedding/manure management that impact the cleanliness of cows and their lying time.

Animal and management factors associated with weight gain in dairy calves and heifers on smallholder dairy farms in Kenya.

Calf growth is an important determinant of dairy herd productivity, particularly in countries where the dairy industry is expanding, such as Kenya. Our objective was to determine factors associated with weight gain in randomly selected dairy calves and heifers in smallholder dairy farms (SDF) in Kenya. A cross-sectional study on a census of 321 calves and heifers (dairy calves and heifers up to 36 months of age), sampled from 200 randomly selected SDF in Naari, Kenya, formed the study population. Youngstock management was recorded using a questionnaire. Biodata were obtained through subsequent physical examination and heart girth measurement. Descriptive statistical analyses were conducted, and mixed model regression was used for identification of factors associated (p < 0.05) with the natural log transformation of estimated average daily weight gain (ADG). Median and mean ADG of the youngstock were 360 and 443 (s.d. = 375) g day-1, respectively. In the final model, ADG was highest in pre-weaned calves and declined with age. Supplementing with quality hay during the dry season at least weekly was associated with increased ADG. There was an interaction between breed and historical disease on ADG such that disease was associated with decreased ADG in Bos taurus breeds, while ADG in Bos indicus breeds was not affected by disease. There was a significant interaction between education levels of the husband and wife caretakers; when the man's education was low (having less than or equal to primary school), ADG was highest when the woman had not completed primary school, but was lower when the woman had completed primary, secondary or tertiary education, possibly because such women worked off-farm more often. General growth performance of animals on these farms was lower than benchmarked standards recommended for optimum dairy production but within previously reported ranges for the East African region. Supplementation of diets (with hay and/or concentrates) is recommended for optimum growth in calves and heifers, especially in the dry season. If nutritional management of Bos taurus youngstock is not improved, crosses of Bos indicus could be better suited for the current nutritional management systems in SDF in Meru having calf disease problems. Interventions to support educating women (the primary caretakers of the cattle) and men in the community on calf management should be initiated, preferably with shared on-farm responsibilities. Training in better management, even for learned farmers, would be critical to better calf growth.

Short communication: Extended-spectrum cephalosporin-resistant Escherichia coli in colostrum from New Brunswick, Canada, dairy cows harbor blaCMY-2 and blaTEM resistance genes.

Dairy calves are colonized shortly after birth by multidrug resistant (MDR) bacteria, including Escherichia coli. The role of dairy colostrum fed to calves as a potential source of MDR bacteria resistance genes has not been investigated. This study determined the recovery rate of extended-spectrum cephalosporin-resistant (ESC-R) E. coli in colostrum from cows. The ESC-R E. coli isolates were further investigated to determine their phenotypic antimicrobial resistance pattern and the genes conferring ESC-R. Fresh colostrum was collected from 452 cows from 8 dairy herds in New Brunswick, Canada. The ESC-R E. coli was isolated from the colostrum by using the VACC agar, a selective media for extended-spectrum ß-lactamase producing Enterobacteriaceae. Minimum inhibitory concentration was determined for all the suspected ESC-R E. coli isolates using a commercial gram-negative broth microdilution method. Two multiplex PCR were conducted on all the suspected ESC-R E. coli isolates to determine the presence of the blaCTX-M (groups 1, 2, 9, and 8/25) blaCMY-2, blaSHV, and blaTEM resistance genes. The ESC-R E. coli were detected in 20 (4.43%) of the colostrum samples. At least 1 ESC-R E. coli isolate was detected in 6 (75%) of the dairy herds. All ESC-R E. coli had MDR profiles based on minimum inhibitory concentration testing. No blaCTX-M groups genes were detected; however, the blaCMY-2 gene was detected in 9 or 20 (45%) and blaTEM was detected in 7 of 20 (35%) of the ESC-R E. coli. No ESC-R E. coli had both blaCMY-2 and blaTEM resistance genes. This is the first report of blaCMY-2 and blaTEM genes found in E. coli isolates cultured from dairy colostrum to our knowledge.

Assessment of Effectiveness of Control Strategies Against Simulated Outbreaks of Highly Pathogenic Avian Influenza in Ontario, Canada.

The North American Animal Disease Spread Model (NAADSM) is a stochastic model framework developed to simulate the spread of highly contagious diseases of livestock and poultry, such as foot-and-mouth disease and highly pathogenic avian influenza (HPAI). The objective of this study was to make recommendations on the most effective HPAI control policy for Canada, specifically, on the effect of different speeds of detection, effectiveness of movement restrictions and stamping-out and ring-culling strategies on the magnitude of an HPAI outbreak. In addition, the effect of introduction of infection in a range of multiple farms simultaneously was also evaluated. A total of 21 060 scenarios, defined as different combinations of parameters for various epidemiological conditions and control measures, were created to simulate the number of poultry flocks that would become infected as a result of an incursion of HPAI. Each scenario was parameterized in NAADSM and replicated 1000 times, generating the median number of flocks infected at the end of the simulated outbreak for each scenario. Negative binomial regression analysis was used to model significant explanatory variables of the median number of flocks infected at the end of each simulated outbreak for each of the 21 060 scenarios. The final model included the following explanatory variables: number and type initially infected flock(s), density of flocks within the county where the initially infected flock(s) was located, probability of transmission through indirect contact, subclinical spread of the infection, speed of detection and a two-way interaction between intensity of bird destruction strategy and movement restriction effectiveness to reduce transmission through direct and indirect contacts. The modelling results suggested that stamping out of the detected infected flocks, without ring culling, in combination with effective movement restrictions on direct and indirect contacts, would be the most appropriate policy for 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.

Risk factors associated with Cryptosporidia, Eimeria, and diarrhea in smallholder dairy farms in Mukurwe-ini Sub-County, Nyeri County, Kenya.

AIM: This study was undertaken to determine the household, calf management, and calf factors associated with the occurrence of Eimeria, Cryptosporidia, and diarrhea in pre-weaned calves reared in smallholder dairy farms in Mukurwe-ini Sub-County of Nyeri County, Kenya. In addition, the study also evaluated factors associated with average daily weight gain in the same pre-weaned calves. MATERIALS AND METHODS: A total of 112 newborn calves (63 males and 49 females) on 111 farms (1 set of twins) were followed for 2 months between June 2013 and August 2013. Two calves were lost to follow-up. A pre-tested questionnaire was used to collect data on household characteristics and calf management practices in the 111 selected farms. On the first visit to the farm (within 7 days of the birth of the calf), blood samples were collected from the jugular vein to assess the level of maternal immunity acquired by the calf, by determining the serum total protein and selenium concentration. At 4 and 6 weeks of age, fecal samples from the calves were collected to assess the presence of Cryptosporidia and Eimeria oocysts. Every 2 weeks for 2 months, the calves and their environments were examined, their 2-week consumption and health history were recorded, and weights were estimated with a weight tape. Each of the factors was evaluated in a univariable regression model and only those found to be significant (p≤0.20) were included in a multivariable model. Elimination of non-significant factors was done in the multivariable model through a backward elimination procedure so that only those variables which were confounders, and/or significant at (p≤0.05) remained in the final model. RESULTS: About 37% (41/110) of the calves experienced diarrhea at least once during the 2-month study period. The overall period prevalence of Eimeria and Cryptosporidia was 42.7% (47/110) and 13.6% (15/110), respectively. Low serum protein was associated with 1.8 and 2.4 times the odds of Eimeria and Cryptosporidia infections, respectively. Lack of supervision of calf birth and low serum total protein were both associated with 1.3 times the odds of diarrhea incidence. Dirty calf pens, feeding <5 L of milk/day, and infection with Eimeria were associated with 0.105, 0.087, and 0.059 kg, respectively, reduced average daily weight gain of the calves. CONCLUSION: In the Kenyan context, calf diarrhea risk could be reduced through better supervision of parturition and colostrum provision. Specifically, the risk of Eimeria and Cryptosporidia infections could be reduced by optimizing the passive transfer of immunity to the newborn calves. Average weight gains of calves could be improved by good colostrum provision, pen hygiene, and preventing Eimeria infections.

Evaluation of the utility of subjective clinical parameters for estimating fecal egg counts and packed cell volume in Canadian sheep flocks.

A study was conducted in sheep on Canadian farms to describe the relationship between packed cell volume (PCV) or fecal egg counts (FEC) and subjective clinical parameters that may indicate the severity of parasitic gastroenteritis. Twenty-one farms in Ontario (ON) and 8 farms in Quebec (QC) were purposively selected and visited during April-May (spring) and August (summer) 2007. At each farm visit, blood and fecal samples were collected from 10 ewes and 10 female lambs; body condition score (BCS), dag score (DS), fecal consistency score (FCS) and FAMACHA score were recorded for all sampled sheep. Packed cell volume was determined for all blood samples, and FEC were performed for all fecal samples. Summary statistics and simple correlations were performed for the parameters recorded. Two mixed models with random effects at the farm level were developed; one using PCV as the response variable and another using the natural log of eggs per gram of feces (lnEPG). Finally, the residuals from both models were correlated to the covariates in the models. The mean PCV values during the spring were 29.7% and 36.7% for lambs, and 28.8% and 31.1% for ewes, in ON and QC, respectively. During the summer, the mean PCV was 32.0% and 32.8% for lambs, and 30.1% and 29.9% for ewes, in ON and QC, respectively. The arithmetic mean FEC per gram of feces (EPG) during the spring was 3 and 2 for lambs, and 1266 and 789 for ewes, in ON and QC, respectively, whereas during summer the arithmetic mean EPG was 907 and 237 for lambs, and 458 and 246 for ewes, in ON and QC, respectively. Results from simple correlations indicated that PCV was negatively correlated with lnEPG (r = -0.255; r(2) = 6.5%) and FAMACHA (r = -0.312; r(2) = 9.7%), and positively correlated with BCS (r = 0.317; r(2) = 10%). LnEPG was negatively correlated with BCS (r = -0.232; r(2) = 5.4%) and PCV (r = -0.255; r(2) = 6.5%), but positively correlated with FAMACHA (r = 0.178; r(2) = 3.2%) and DS (r = 0.086; r(2) = 0.7%). Results from the models indicated that PCV and lnEPG residuals were negatively correlated with FAMACHA, FCS and almost all categories of BCS and DS, although the correlations were very low. The main results from this study suggested that none of the subjective clinical parameters evaluated were highly correlated with PCV or lnEPG and therefore were not good predictors of lnEPG or PCV on the studied farms in Ontario and Quebec.

A systematic review and meta-analysis of factors associated with anthelmintic resistance in sheep.

BACKGROUND: Anthelmintic drugs have been widely used in sheep as a cost-effective means for gastro-intestinal nematode (GIN) control. However, growing anthelmintic resistance (AHR) has created a compelling need to identify evidence-based management recommendations that reduce the risk of further development and impact of AHR. OBJECTIVE: To identify, critically assess, and synthesize available data from primary research on factors associated with AHR in sheep. METHODS: Publications reporting original observational or experimental research on selected factors associated with AHR in sheep GINs and published after 1974, were identified through two processes. Three electronic databases (PubMed, Agricola, CAB) and Web of Science (a collection of databases) were searched for potentially relevant publications. Additional publications were identified through consultation with experts, manual search of references of included publications and conference proceedings, and information solicited from small ruminant practitioner list-serves. Two independent investigators screened abstracts for relevance. Relevant publications were assessed for risk of systematic bias. Where sufficient data were available, random-effects Meta-Analyses (MAs) were performed to estimate the pooled Odds Ratio (OR) and 95% Confidence Intervals (CIs) of AHR for factors reported in ≥2 publications. RESULTS: Of the 1712 abstracts screened for eligibility, 131 were deemed relevant for full publication review. Thirty publications describing 25 individual studies (15 observational studies, 7 challenge trials, and 3 controlled trials) were included in the qualitative synthesis and assessed for systematic bias. Unclear (i.e. not reported, or unable to assess) or high risk of selection bias and confounding bias was found in 93% (14/15) and 60% (9/15) of the observational studies, respectively, while unclear risk of selection bias was identified in all of the trials. Ten independent studies were included in the quantitative synthesis, and MAs were performed for five factors. Only high frequency of treatment was a significant risk factor (OR=4.39; 95% CI=1.59, 12.14), while the remaining 4 variables were marginally significant: mixed-species grazing (OR=1.63; 95% CI=0.66, 4.07); flock size (OR=1.02; 95% CI=0.97, 1.07); use of long-acting drug formulations (OR=2.85; 95% CI=0.79, 10.24); and drench-and-shift pasture management (OR=4.08; 95% CI=0.75, 22.16). CONCLUSIONS: While there is abundant literature on the topic of AHR in sheep GINs, few studies have explicitly investigated the association between putative risk or protective factors and AHR. Consequently, several of the current recommendations on parasite management are not evidence-based. Moreover, many of the studies included in this review had a high or unclear risk of systematic bias, highlighting the need to improve study design and/or reporting of future research carried out in this field.

A longitudinal study on the effect of lambing season on the periparturient egg rise in Ontario sheep flocks.

The epidemiology of the periparturient egg rise (PPER) of gastrointestinal nematodes (GINs) in sheep remains unclear, and may be influenced by the lambing season. This longitudinal study was performed to determine the effect of out-of-season lambing on the PPER in ewes in Ontario, and whether total plasma protein (TPP) and packed cell volume (PCV) were associated with the PPER. Six farms that practiced out-of-season lambing were enrolled, and sampled for three consecutive lambing seasons (winter, spring and autumn). For each lambing season, all farms were visited five times. On the first visit for each lambing season, 15-20 pregnant ewes and 15-20 non-pregnant/early gestation ewes were randomly selected. At each visit, fecal samples were collected from all selected animals and processed individually to measure GIN fecal egg counts (FECs). Blood samples were collected on three visits in each lambing period and processed to measure TPP and PCV. The ewes were classified into one of five production stages (maintenance [i.e. not pregnant], early or late gestation [<120 d and ≥ 120 d, respectively], and early or late lactation [<40 d and ≥ 40 d, respectively]) based on information collected during farm visits. Linear mixed models were developed for the TPP, PCV and logarithmic-transformed FEC (lnFEC). During the winter and spring lambing season, the FECs increased gradually over the gestation period and peaked during lactation, with these increases being larger in ewes with a low PCV (three-way interaction in the final model). In the autumn lambing season, the FECs started off higher in early gestation, and increased rapidly to peak in late gestation, particularly for animals with low PCV levels. In the TPP model, PCV and lnFEC were positively associated with TPP. During both autumn and winter lambing seasons, the TPP decreased from maintenance throughout gestation and early lactation, followed by an increase in late lactation, except for when there were high FECs. During the spring lambing season, TPP peaked at early gestation, and then decreased in late gestation, to increase more gradually over lactation. In the PCV model, PCV increased with TPP and decreased exponentially with increases in lnFEC. The PPER occurred during all three lambing seasons, and its magnitude and distribution varied with the lambing season, suggesting that the PPER in ewes depends on both environmental and animal physiological factors, an important consideration when implementing preventive parasite control strategies on sheep farms that practice out-of-season lambing.

Anthelmintic resistance in sheep flocks in Ontario, Canada.

Gastrointestinal nematodes (GIN) are a significant constraint to pasture-based sheep production worldwide. Anthelmintic resistance (AR) has been reported in most sheep-raising areas in the world, yet little is known about the AR status in Canada. This study was conducted to determine the frequency of AR in GIN in sheep flocks in Ontario, Canada. Forty-seven sheep flocks were enrolled in the study, and their level of parasitism was monitored monthly throughout a grazing season by analyzing owner-acquired fecal samples from 15 grazing lambs per flock. When the mean GIN fecal egg count (FEC) reached a threshold of 200 eggs per gram (epg), oral ivermectin was supplied to producers to check ivermectin efficacy; the reduction in mean FEC 14 days after ivermectin treatment was calculated. 'Drench failure' was defined as a reduction in mean FEC of <95%. In those flocks with apparent drench failure, researchers performed a Fecal Egg Count Reduction Test (FECRT), dividing sheep into 4 treatment groups (n=10-15): control (i.e. untreated), ivermectin, and, if sufficient numbers of animals - fenbendazole and levamisole. AR was defined as a reduction in mean FEC <95% and a lower 95% confidence interval <90%. Larval cultures were performed on pooled post-treatment FECRT samples. Larval Development Assays (LDAs) to detect the presence of resistance to thiabendazole and levamisole were performed prior to the ivermectin drench check on pooled owner-acquired fecal samples that reached the 200 epg threshold. Approximately 89% (42/47) of the farms reached the FEC threshold of 200 epg; 93% (39/42) of these farms performed an ivermectin drench check, and 88% (34/39) of these farms had drench failure. The FECRT was performed on 29 of the 34 farms. Resistance to ivermectin, fenbendazole and levamisole was demonstrated on 97% (28/29), 95% (19/20) and 6% (1/17) of the farms tested, respectively, with considerable variability in resistance levels among farms. Haemonchus sp. was the most commonly cultured parasite from post-treatment fecal samples. LDA results for 21 farms were available; of these, 14% (3/21) and 62% (13/21) had low and high levels of thiabendazole resistance, respectively, while none of the farms exhibited resistance to levamisole. Amongst these tested farms, resistance to both ivermectin and benzimidazoles was very common. These findings strongly suggest that AR, particularly in Haemonchus sp., is a serious problem in these sheep flocks. Thus, marked changes in GIN management need to be instituted immediately to mitigate a worsening situation.

A systematic review-meta-analysis of primary research investigating the effect of selected alternative treatments on gastrointestinal nematodes in sheep under field conditions.

Selected alternative treatments for preventing or controlling gastrointestinal nematodes (GIN) in sheep under field conditions were evaluated using a systematic review-meta-analysis methodology. Forty-three publications reporting 51 studies (21 controlled studies (CS) and 30 challenge studies (ChS)) and 85 unique treatment comparisons were included in the review. The alternative treatment categories were nutraceuticals (28 studies), breeding for genetic resistance (12), nutritional manipulation (6), homeopathies (2), administration of copper oxide wire particles (2), and biological control (1). Random effect meta-analyses (MA) and meta-regression were performed with the natural logarithm of the difference in means (lnMD) between the control and treatment groups, for fecal egg counts per gram of wet feces (FEC), worm counts (WC) or fecal egg counts per gram of dry matter (FECDM) as the outcome. Treatment effect estimates (lnMD) were back-transformed to their count ratios (CR), a relative measure of effect for controlled versus treated groups, for presentation of results. Significant heterogeneity was observed for both CS and ChS that evaluated nutraceuticals, genetic resistance and nutrition treatments. MA of ChS that investigated nutraceuticals resulted in a significant overall CR of 1.62 (P<0.01) and 1.64 (P<0.01) for FEC and FECDM, respectively and a marginal significant CR of 1.14 (P=0.06) for WC, all favoring the treated groups. MA of CS and ChS that investigated genetic resistance resulted in a significant overall CR of 5.89 and 15.42, respectively (P<0.01), again favoring treated groups. MA of CS that investigated homeopathies with FEC as an outcome were homogenous (I(2)=0.0%) and resulted in a non-significant pooled CR of 1.61. ChS investigating copper oxide wire particle treatments and WC as an outcome, were homogenous (I(2)=0.0%) and had a marginally significant pooled CR of 1.68 (P=0.06). Publication bias was observed for ChS with WC outcomes, indicating that small size studies reporting non-significant CR, were less likely to be published than similar studies that found a significant CR. In a meta-regression, randomization (6.2%) and study size (29.2%) were the main factors contributing to the total variation when the outcome was FEC, and none of the variables contributed to between study heterogeneity. When the outcome was WC, type of treatment was the only significant covariate, explaining 6% of the heterogeneity and 38.5% of the total variation. The methodological soundness and reporting of primary research in the selected studies were low. Our results indicate that from the studied alternative treatments, nutraceuticals and use of genetically resistant sheep might be more promising for control of GINs in sheep.

Monensin use against Neospora caninum challenge in dairy cattle.

Using a randomized controlled trial design, a randomly allocated intervention group of 15 cows received a slow-release bolus that delivered 100 days of monensin. The negative control group of 15 cows received a placebo bolus that was identical to the monensin bolus, except without the monensin. Two weeks after bolus administration, all cows were challenged with a 2 ml subcutaneous injection of a live tachyzoite suspension. Whole blood and serum samples were collected from each cow every week for the first month post-challenge, and then every 2 weeks for the next 2 months. The extracted DNA from whole blood was tested for the Nc-5 gene fragment of Neospora caninum using a quantitative real time polymerase chain reaction. Serum was tested for antibodies to N. caninum using the IDEXX ELISA. Cows treated with monensin boluses had a significantly lower humoral immune response than cows treated with placebo boluses at one time point post-challenge (week 4 post-challenge). However, when adjusting for repeated measures within cows, the P value for this humoral difference was 0.098. No DNA for N. caninum was detected in either group, likely due to study design features.

Evaluation of a British computer model to simulate gastrointestinal nematodes in sheep on Canadian farms.

With increasing levels of anthelmintic resistance worldwide and a growing demand to produce more organic products, utilisation of control strategies for gastrointestinal nematodes (GIN) that minimize the use of anthelmintics becomes even more important. This study evaluated the farm-level performance of an existing predictive sheep parasite model from the United Kingdom (UK), using Canadian data. The UK model simulates the epidemiology of three major GIN species of interest (Teladorsagia spp., Haemonchus spp. and Trichostrongylus spp.) and provides a prediction about seasonal parasite levels of lambs and ewes. Model inputs were generated by using data from the first 2 years of a 3-year study (2006-2008) which examined the epidemiology of GIN parasitism in Ontario sheep flocks. Required input data included ewe parasite egg output, pasture-related information and management dynamics. Farm visits in 2006 and 2007 provided relevant data that were collected monthly during the grazing season, on six and seven occasions respectively. These data were collected from 10 ewes and 10 lambs on each farm. For 23 Ontario farms with available data, only 11 farms in 2006 and 14 in 2007 had suitable data to run in the model because the Canadian study was not specifically designed with this simulation model in mind. Observed values for faecal egg counts (FEC) were compared to the model FEC outputs and assessed using linear regression analysis. There was adequate fit between observed and simulated data for 8 of the 11 farms modelled using data generated in 2006 (F=7.55-42.66, df=10-11, R(2)=0.43-0.81, p=0.021 to <0.001) and with 8 of the farms modelled using data generated in 2007 (F=5.56-35.82, df=9-11, R(2)=0.36-0.82, p=0.040 to <0.001). We suggest that the poor fit between observed and simulated data for some data sets may be attributable to low-level infection on farms making regression difficult due to insensitivity of the egg count method at low values, or a pattern for immunity in ewes that contradicted the model assumptions. Required model modifications focused on accommodating the differences between UK and Canadian management styles; specifically the practice of bringing lambs indoors for weaning which was sometimes used on Canadian farms.

Prevalence and distribution of gastrointestinal nematodes on 32 organic and conventional commercial sheep farms in Ontario and Quebec, Canada (2006-2008).

In order to characterize the epidemiology of sheep gastrointestinal nematodes in organic and conventional flocks in Canada, a longitudinal study was carried out from May 2006 to March 2008 on 32 purposively selected farms in Ontario (ON) and Quebec (QC): 8 certified organic (CO), 16 non-certified organic (NCO), and 8 conventional (C) farms. On each farm, 10 ewes and 10 female lambs were selected. Farm visits were undertaken monthly during the grazing season, and twice in the winter. At each visit, individual fecal samples were taken, and pasture samples were obtained during the grazing season. In addition, body condition score was recorded for all sheep. Fecal egg counts per gram of feces (EPGs) were determined for all fecal samples, and infective larvae (L(3)) were identified in fecal samples (lambs and ewes separately) and pasture samples from farms. Necropsies of 14 lambs from 7 of the 23 Ontario farms were performed at the end of the grazing season in 2006. The mean EPG for year 1 (May 2006 to March 2007) was 181 (range=0-9840) and 351 (range=0-18,940) for the ewes in ON and QC, respectively, and for the lambs was 509 (range=0-25,020) and 147 (range=0-3060) for ON and QC, respectively. During year 2 (April 2007 to March 2008), the mean EPG was 303 (range=0-21,160) and 512 (range=0-22,340) for the ewes in ON and QC, respectively, and for lambs was 460 (range=0-26,180) and 232 (range=0-8280) for ON and QC, respectively. Although the overall mean EPGs were not remarkably high, there were months of higher EPG such as May-June for ewes and July-August for lambs in both provinces. Pasture infectivity was highest in May-June and September. There was a general trend for the CO farms to have lower mean EPG than NCO and C farms. Fecal cultures demonstrated that the most predominant nematode genera were Teladorsagia sp., Haemonchus sp. and Trichostrongylus spp. Pasture infectivity was highest during June-July (984 L3/kg DM) in ON farms and September (mean=436 L3/kg DM) in QC farms during year 1. In year 2, the highest peak was during October in ON (mean=398 L3/kg DM) and July in QC (239 L3/kg DM). Trichostrongylus axei and Trichostrongylus colubriformis were the species most frequently identified from necropsies (36.44% and 38.26%, respectively) at the end of the grazing season in 2006, with Haemonchus contortus and Teladorsagia circumcincta being the next most commonly identified.