In situ provision of drinking water to grazing dairy cows improves milk production

AIMS: To determine the effect of providing water within the area grazed by dairy cows on milk yield and quality, compared to requiring cows to walk to a distant water trough, on a dairy farm in the Pampa region of Argentina during summer.

METHODS: Holstein dairy cows were allocated to two herds with similar parity, days in milk and milk production. They were grazed in one paddock that was divided in two, with a fixed water trough at one end. Cows were moved twice daily to grazing plots within the paddock. Control cows (n=66) could only access water from the fixed trough, whereas supplemented cows (n=67) also received water from a mobile trough within the grazing plot. Milk production of each cow, and water consumption of the two herds were measured daily over 62 days. Milk composition for each herd was determined weekly from Days 18 to 60 of the study, and grazing behaviour was observed between 08:00 and 16:00 hours on Days 11–15, 19–22 and 39–43.

RESULTS: Over the 62 days of the study, supplemented cows produced 1.39 (SE 0.11) L/cow/day more milk than Control cows (p=0.027). Estimated mean daily water intake was 50.4 (SE 2.1) L/cow/day for supplemented cows and 58.2 (SE 2.7) L/cow/day for Control cows (p=0.004). Percentage total solids in milk was higher for supplemented (12.5 (SE 0.06)%) than Control (12.4 (SE 0.04)%) cows (p=0.047). During the periods of behavioural observation, a higher percentage of cows in the water supplemented than the Control herd were observed in the grazing area (p=0.012).

CONCLUSIONS AND CLINICAL RELEVANCE: This preliminary study demonstrated that provision of water to dairy cows within the grazing plot was beneficial for milk production and composition, and may be associated with longer periods spent within the grazing area, during hot weather in the Pampa region of Argentina.     

An assessment of the herd-level impact of the Theileria orientalis (Ikeda) epidemic of cattle in New Zealand, 2012–2013: a mixed methods approach

AIM: To estimate incidence risk, cumulative mortality and case fatality rate within herds affected by bovine anaemia associated with Theileria orientalis infection (TABA), in New Zealand during the early phase of the epidemic (August 2012–September 2013).

METHODS: A mixed methods approach was utilised to integrate data from various sources, including a detailed questionnaire carried out on 18 dairy farms which had experienced cases of TABA; a brief telephone survey of an additional 139 case farms; and data extracted from a Ministry for Primary Industries database for a further 42 case farms. The subsequent analysis determined incidence risk, cumulative mortality and case fatality rates for beef and dairy herds.

RESULTS: Data were analysed from 196/263 (74%) known case farms at the date of closing the questionnaires. These farms contained 99,505 cattle; 2,847 animals were reported with clinical disease, and a further 590 animals were recorded as having died from TABA. The within-herd incidence risk, cumulative mortality and case fatality rate were consistent between the three data sources, did not differ between beef and dairy herds, and were estimated to be 0.97 (inter-quartile range (IQR) 0.36–2.07)%, 0.23 (IQR 0.00–0.66)% and 16.67 (IQR 0.00–33.33)%, respectively. There was substantial variability in the level of impact, with 22 farms severely affected (incidence risk >5% and cumulative mortality >5%).

CONCLUSIONS: The mixed methods approach was effective in dealing with the disparate data sources. The inclusion of the majority of farms known to be affected at the time the questionnaires were performed implies that the information is likely to be representative. The collective outputs of the analyses represent the best estimate available of within-herd measures of disease frequency in the early phase of the epidemic in New Zealand. The limitations of the data imply that their primary application may be to inform the design of subsequent structured observational field studies.

CLINICAL RELEVANCE: The results of this study provide information on the impact of TABA on cattle farms during the emergence and early spread of the disease, as well as for generating hypotheses on causal mechanisms and risk factors that may influence the course of disease.     

Factors affecting the variability in cracked and dirty eggs and egg production profitability on an integrated poultry operation

1. A number of factors causing variability in the percentages of cracked, and dirty eggs and weekly standard margin (WSM) of returns from eggs over production costs were examined on an integrated commercial poultry plant in Scotland.

2. As the bird aged, the percentage of cracked eggs increased (P <0.01) and the percentage of grade A eggs and WSM decreased (P <0.01). Cracks in dirty eggs (10.1%) were more than double those in all eggs laid (4.9%).

3. Seasonal effects on percentage cracked eggs and percentage grade A eggs were one‐third the magnitude of those due to age but were significant (P <0.05).

4. Variability in percentage cracked eggs, dirty eggs and WSM accounted for by the factors measured, were 72, 64 and 92% respectively.

5. The variability in WSM was significantly affected by percentage lay, food consumption and age but not by percentage cracked eggs, originally dirty and grade A eggs.

6. Flock management and climate inside the laying house each increased the amount of variability accounted for in the percentage cracked eggs and dirty eggs by at least 10%.     

Effect of using an internal teat sealant at drying-off in cows wintered on forage crops in New Zealand on culling in the dry period and early lactation

AIMS: To determine the impact of treatment with internal teat sealant (ITS) compared to no treatment at drying-off on culling during the dry period and 90 days after calving, for cows wintered on forage crops.

METHODS: In four dairy herds in the South Island of New Zealand, cows with no history of clinical mastitis or somatic cell counts >100,000 cells/mL during the 2015–16 season were randomly assigned to treatment with ITS in each quarter (ITS group) or no treatment (Control group). Cows were otherwise treated similarly, wintered on forage crops and transferred to pasture for calving and lactation. Culling was defined as an unplanned exit from the herd, including cows sold for slaughter, cows slaughtered for salvage value and cows that died on farm. Culls and cull dates were recorded between drying-off and 90 days after calving.

RESULTS: Between drying-off and 90 days after calving 24/491 (4.9%) cows in the ITS group and 45/473 (9.5%) cows in the Control group were culled (RR=0.51; 95% CI=0.75–0.83), and between 30 days before calving and 90 days after calving 20/491 (4.1%) cows in the ITS group and 40/473 (8.5%) cows in the Control group were culled (RR=0.48; 95% CI=0.29–0.81). In the final multivariable logistic regression model, adjusting for dry-period length, cow age, breed and farm, the OR for culling in the study period was 0.43 (95% CI=0.23–0.81) for cows in the ITS compared with the Control group. For a Friesian/Jersey cow, aged 4–8 years, with a dry period of 30–80 days, dried-off without ITS, the probability of culling in the study period was 0.10 (95% CI=0.06–0.16), and for such a cow treated with ITS the probability was 0.05 (95% CI=0.03–0.08).

CONCLUSIONS AND CLINICAL RELEVANCE: In these four herds, the use of ITS at drying-off reduced the incidence of culling between drying-off and 90 days after calving. The use of ITS at drying-off in cows prior to wintering on forage crops may provide additional benefit to farmers through reduced incidence of culling and should be considered in any cost–benefit analysis of its use.     

Attitudes of farm consultants in the South Island of New Zealand towards the role of veterinarians in farm businesses

AIMS: To assess the attitude of dairy farm consultants to the role of veterinarians on dairy farms and whether they viewed veterinary advice as impartial, free from commercial bias and central to farm productivity and profitability.

METHODS: A telephone survey was commissioned in September 2014 of 36 full-time farm consultants in the Canterbury and Otago region of New Zealand using a pre-prepared questionnaire to explore their attitudes towards the veterinary profession. Of those approached, 25 completed the survey.

RESULTS: The consultants surveyed agreed or strongly agreed (21/23) that they were the custodians of animal health expenditure on farms, which was seen as an expense to be controlled (19/25 agreed or strongly agreed). This view was held more strongly (9/9 agreed or strongly agreed) by consultants with >5 years’ professional experience, compared to 10/16 consultants with ≤5 years’ experience. Most consultants (24/25) disagreed that they did not respect veterinary advice, but agreed (24/25) that veterinarians almost always had a vested interest in the advice that they gave. The role of veterinarians was seen by respondents to be mainly treatment of sick animals (22/25) and provision of animal health products (24/25), but not in maximising farm profitability (selected by 8/25 respondents). Consultants viewed their own roles as providing advice on the influence of animal health on farm profitability (21/25), nutrition (22/25) and reproduction (20/25). Most respondents (21/25) stated that reducing disease and animal health issues was important, but they (21/25) also identified a reduction in farm animal health expenditure as a measure of success. Only 7/25 consultants felt that they should work in partnership with veterinarians.

CONCLUSIONS: This was a small scale study from one region of New Zealand but it indicates that consultants are ambivalent about the role and value of working more closely with veterinarians, and about the benefit that veterinary intervention may bring to a farm’s profitability.

CLINICAL RELEVANCE: More successful veterinary involvement on dairy farms will follow from a better understanding of how other rural professionals are involved in the farm’s management and in meeting the individual farmer’s goals and motivations.     

Comparison of cephalonium alone and in combination with an internal teat sealant for dry cow therapy in seasonally calving dairy cows

AIM: To assess the effect of combining an internal teat sealant (ITS) and a long-acting cephalonium-based dry cow therapy (DCT) on the prevalence of cows with a somatic cell count (SCC) >150,000 cells/mL 60–80 days after calving, and the incidence of clinical mastitis diagnosed by farm staff in the first 100 days after calving.

METHODS: Cows from a spring-calving, pasture-based, dairy farm in the South Canterbury region of New Zealand were randomly allocated to receive cephalonium DCT (n=289) or cephalonium and internal teat sealant (n=304) at the end of lactation. Cows were inspected twice daily by farm staff during the dry period and following calving for signs of mastitis. Individual SCC were determined from herd tests conducted in the previous lactation and following calving. Logistic regression models were used to determine relationships with the prevalence of cows with a SCC >150,000 cells/mL after calving, and survival analysis was used to model time to the first case of clinical mastitis following calving at the cow and quarter level.

RESULTS: The OR for a cow with a SCC >150,000 cells/mL after calving, including age and individual SCC in the preceding lactation in the model, was 0.53 (95% CI=0.32–0.89) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.017). At the cow level, including age and preceding SCC in the model, the hazard ratio for diagnosis of clinical mastitis by farm staff in the first 100 days of lactation was 0.60 (95% CI=0.39–0.98) for cows treated with combination therapy compared to cows receiving cephalonium (p=0.04). At the quarter level, the hazard ratio for diagnosis of clinical mastitis, with age included in the model, was 0.41 (95% CI=0.23–0.74) for the combination therapy compared to cephalonium alone (p<0.001).

CONCLUSIONS: The combination of internal teat sealant and cephalonium DCT was more effective than cephalonium alone at reducing clinical mastitis diagnosed by farm staff in the 100 days after calving, and the prevalence of cows with a SCC >150,000 cells/mL 60–80 days after calving.

CLINICAL RELEVANCE: This study adds to the evidence that the prevention of intra mammary infections throughout the dry period and up to calving by using combination therapy is important in reducing the incidence of farmer-diagnosed clinical mastitis and prevalence of cows with a SCC >150,000 cells/mL 60–80 days after calving.     

Antimicrobial usage and risk of retreatment for mild to moderate clinical mastitis cases on dairy farms following on-farm bacterial culture and selective therapy

AIMS: To assess antimicrobial usage for treatment of mild to moderate clinical mastitis, and risk of retreatment, following implementation of an on-farm bacterial culture system and selective therapy based on culture results, and to assess compliance with treatment decision tree protocols and the level of agreement between results from on-farm culture and laboratory-based microbiology methods.

MATERIALS AND METHODS: Herdowners from seven dairy herds were asked to collect milk samples from cases of mild to moderate clinical mastitis between July 2015 and May 2016. All samples were cultured on-farm using a commercially available selective media and were also submitted for laboratory-based culture. Within sequential pairs of cows with mastitis, half were assigned to be treated without regard to culture results (Blanket group), and half were treated based on the on-farm culture results (Selective group) according to decision tree diagrams provided to the farmers. Culture results, treatments, and retreatments for clinical mastitis were recorded. The sum of the daily doses of antimicrobials used per cow, the number of retreatments and interval to first retreatment were compared between treatment groups.

RESULTS: The geometric mean sum of daily doses for quarters assigned to the Selective (1.72 (95% CI=1.55–1.90)) group was lower than for the Blanket (2.38 (95% CI=2.17–2.60)) group (p=0.005). The percentage of cows retreated for clinical mastitis did not differ between the Selective (21.7 (95% CI=10.5–25.9)%) and Blanket (26.1 (95% CI=20.9–31.3)%) groups (p=0.13), and there was no difference between groups in the hazard that cows would be retreated within 60 days of enrolment (hazard ratio=0.82 (95% CI=0.39–1.69); p=0.59). Compliance with the treatment protocols was higher amongst quarters assigned to the Selective (199/233; 85.4%) compared with the Blanket (171/249; 68.7%) group (p<0.001), and varied between farms from 64–94%. The overall agreement between results from on-farm and laboratory culture was 188/331 (56.9%; kappa=0.31; p<0.001), but varied between farms from 44.7–88.2% (p<0.001).

CONCLUSIONS: Use of on-farm culture with selective antimicrobial therapy resulted in approximately 25% lower antimicrobial usage, but was not associated with an increase in the proportion of cows retreated for clinical mastitis.

CLINICAL RELEVANCE: This study has demonstrated that on-farm culture and selective therapy based on culture results can be implemented on-farm. However, farms varied in their implementation of both the treatment protocols and microbiology procedures. Where such systems are to be used on-farm, specific training and on-going monitoring is required.     

Investigation of bovine haemoplasmas and their association with anaemia in New Zealand cattle

CASE HISTORY AND CLINICAL FINDINGS: A dairy cow, from a herd in the Waikato region of New Zealand, was reported with regenerative anaemia on 12 September 2014. Testing of blood from the animal using PCR assays for Theileria orientalis produced a negative result for both Chitose and Ikeda types.

LABORATORY FINDINGS: Using PCR and DNA sequencing, blood from the cow was positive for Candidatus Mycoplasma haemobos. Further testing of another 12 animals from the case herd, 27 days after the affected cow was first reported, showed 11 animals were positive for Candidatus M. haemobos or Mycoplasma wenyonii in the PCR. None of these cattle were clinically anaemic or positive for T. orientalis Ikeda type using PCR.

A convenience sample of 47 blood samples from cattle throughout New Zealand, submitted to the Investigation and Diagnostic Centre (Ministry for Primary Industries) for surveillance testing for T. orientalis Ikeda, was selected for further testing for bovine haemoplasmas. Of these samples, 6/47 (13%) and 13/47(28%) were positive for M. wenyonii and Candidatus M. haemobos, respectively. There was no difference in the proportion of samples positive for the bovine haemaplasmas between cattle with anaemia that were negative for T. orientalis (6/20, 33%), or without anaemia or T. orientalis (10/18, 56%), or from cattle herds experiencing anaemia and infection with T. orientalis Ikeda type (3/9, 33%).

DIAGNOSIS: Bovine haemoplasmosis.

CLINICAL RELEVANCE: The presence of bovine haemoplasmas in blood does not establish causality for anaemia in cattle. Diagnosis of anaemia associated with haemoplasmosis would require exclusion of other causes of regenerative anaemia and an association of the agent with anaemia in affected cattle herds. The data collected in this study did not provide evidence that bovine haemoplasmas were associated with a large number of outbreaks of anaemia in cattle in New Zealand.     

Factors affecting hatchability during commercial incubation of Ostrich (Struthio camelus) eggs

1. A batch of 320 ostrich eggs from 9 different farms in Zimbabwe were incubated in a single stage operation and the fate of each was recorded.

2. Hatchability was only 37.2% and the result of high rates of infertility and contamination (22.2% and 22.8% respectively); it varied between eggs from different farms.

3. Embryonic mortality was high at the start and end of incubation, a pattern similar to that of other domestic birds.

4. Mortality of late stage embryos was related to percentage water loss and mass specific water vapour conductance of the shell, with extremes of the ranges causing the highest mortality.

5. Microbial contamination of the eggs was a significant problem and varied in eggs from different farms indicating that more attention is needed in both breeder bird and nest management.     

Backyard chicken keeping in the Greater London Urban Area: welfare status,biosecurity and disease control issues

1. The aim of the study was to collect baseline data on welfare, biosecurity and diseases of backyard chickens kept in the Greater London Urban Area (GLUA), United Kingdom (UK).

2. A total of 65 backyard chicken flock-keepers were recruited from May to July 2010 through adverts on websites, at City farms, veterinary practices and pet feed stores and surveyed by means of a questionnaire. A total of 30 responses were suitable for analysis.

3. Information on keepers’ and flocks’ characteristics, housing and husbandry practices and owners’ knowledge of health problems in chickens and zoonotic diseases was collected. A welfare assessment protocol was developed and the flocks assessed accordingly.

4. Results showed that chickens were generally provided with living conditions that allowed them to perform their natural behaviours.

5. Most of the flock owners did not comply with the regulations of the Department for Environment, Food and Rural Affairs (Defra) on the feeding of catering waste.

6. Disease prevention measures such as vaccination and biosecurity, including limiting the access of human visitors, wild birds and rodents to the flocks were rare.

7. A lack of avian and zoonotic disease knowledge and awareness among the owners has implications for disease control and highlights the need for improved communication between owners, authorities and veterinarians.     

Resynchronising returns to service in anoestrous dairy cows in the South Island of New Zealand

AIMS: To investigate the effect of targeted resynchronisation of cows treated for non-observed oestrus before the planned start of mating (PSM), that were not detected in oestrus or pregnant 23 days after treatment (phantom cows), on the proportion pregnant at 42 days after PSM and the end of mating.

METHODS: Farm staff from eight herds in two regions of the South Island of New Zealand identified 1,819 cows not showing oestrus by 10 days before PSM. These cows were treated with intravaginal progesterone for 7 days, and I/M gonadorelin 10 days and 1 day before PSM. Three days before PSM they were injected with cloprostenol and equine chorionic gonadotrophin, with fixed time artificial insemination (FTAI) at PSM. By 23 days after PSM, 1,218 cows had not returned to oestrus. Of these, 161 cows confirmed not pregnant by transrectal ultrasonography were randomly assigned to no treatment (control group; n=74) or were resynchronised 25 days after PSM using the same treatment programme as above, with FTAI 35 days after PSM (n=87). All cows that returned to oestrus were artificially inseminated until 42 days after PSM, when natural mating was used. All cows were examined using transrectal ultrasonography 80 to 90 days after PSM to confirm conception dates.

RESULTS: Of the 1,819 anoestrous cows treated before PSM, 526 (29 (95% CI=23.1–34.0)%) had not been observed in oestrus by 23 days after PSM and had not conceived, so were diagnosed as phantoms cows. For resynchronised cows, 42/87 (48 (95% CI=37.8–58.8)%) were pregnant by 42 days after PSM compared to 21/74 (28 (95% CI=18.1–38.7)%) control cows (p=0.009). At the end of mating 58/87 (67 (95% CI=56.6–76.7)%) cows in the resynchronised group were pregnant and 46/74 (62 (95% CI=50.9–73.2)%) in the control group (p=0.554). The hazard of conception from 21 to 42 days after PSM was 1.9 (95% CI=1.07–3.12) times greater for resynchronised than control cows (p=0.026).

CONCLUSION: In cows not observed in oestrus and treated before PSM, resynchronisation increased the proportion pregnant by 42 days after PSM.

CLINICAL RELEVANCE: The benefit of resynchronisation depends on the number of anoestrous cows before PSM and the number of phantom cows after PSM. However at the herd-level it is likely that providing advice to reduce the known risk factors for cows not being observed in oestrus before the PSM may well be more cost effective than identifying and treating a sub-population of phantom cows.     

Performance of commercial laying hen genotypes on free range and organic farms in Switzerland,France and The Netherlands

1. A total of 257 farmers with free ranging laying hens (organic and conventional) in Switzerland, France and The Netherlands with 273 flocks were interviewed to determine the relationships between the genotype of the hens, management conditions and performance.

2. Almost 20 different genotypes (brands) were present on the farms. In France, all birds were brown feathered hens laying brown eggs. In Switzerland and The Netherlands, there were brown, white (white feathered hens laying white eggs) and silver (white feathered hens laying brown eggs) hens. In Switzerland, mixed flocks were also present.

3. The overall effect of system (organic vs. conventional free range) on egg production and mortality was significant, with higher mortality and lower egg production among organic hens. In pair wise comparisons within country, the difference was highly significant in The Netherlands, and showed a non-significant tendency in the same direction in Switzerland and France.

4. White hens tended to perform better than brown hens. Silver hens appeared to have a higher mortality and lower production per hen housed at 60 weeks of age.

5. There were no significant relationships between production, mortality, feather condition and use of outside run or with flock size.

6. There was more variation in mortality and egg production among farms with a small flock size than among farms with a large flock size.     

Clinical haematology and biochemistry profiles of cattle naturally infected with Theileria orientalis Ikeda type in New Zealand

AIMS: To present the haematology and biochemistry profiles for cattle in New Zealand naturally infected with Theileria orientalis Ikeda type and investigate if the results differed between adult dairy cattle and calves aged <6 months.

METHODS: Haematology and biochemistry results were obtained from blood samples from cattle which tested positive for T. orientalis Ikeda type by PCR, that were submitted to veterinary laboratories in New Zealand between October 2012 and November 2014. Data sets for haematology and biochemistry results were prepared for adult dairy cattle (n=62 and 28, respectively) and calves aged <6 months (n=62 and 28, respectively), which were matched on the basis of individual haematocrit (HCT). Results were compared between age groups when categorised by HCT. Selected variables were plotted against individual HCT, and locally weighted scatterplot smoothing (Loess) curves were fitted to the data for adult dairy cattle and calves <6 months old.

RESULTS: When categorised by HCT, the proportion of samples with HCT <0.15 L/L (severe anaemia) was greater for adult dairy cattle than for beef or dairy calves, for both haematology (p<0.002) and biochemistry (p<0.001) submissions. There were differences (p<0.05) between adult dairy cattle and calves aged <6 months in the relationships between HCT and red blood cell counts, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentrations, lymphocyte and eosinophil counts, and activities of glutamate dehydrogenase and aspartate aminotransferase. In both age groups anisocytosis was frequently recorded. The proportion of blood smears showing mild and moderate macrocytosis was greater in adults than calves (p=0.01), and mild and moderate poikilocytosis was greater in calves than adults (p=0.005).

CONCLUSIONS AND CLINICAL RELEVANCE: The haematology and biochemistry changes observed in cattle infected with T. orientalis Ikeda type were consistent with extravascular haemolytic anaemia. Adult dairy cattle were more likely to be severely anaemic than calves. There were differences in haematology and biochemistry profiles between adult dairy cattle and calves, but most of these differences likely had a physiological rather than pathological basis. Overall, the haematological changes in calves aged <6 months appeared less severe than in adult dairy cattle.     

Comparative mortality and predation in relation to egg production traits of Rhode Island Red,Black Australorp and Hyblack laying hens in scavenging production systems of rural Malawi

1. Black Australorp (BA), Rhode Island Red (RIR), and Hyblack (HB) birds were used in farm and field scavenging systems in Malawi, to study mortality through disease and predation in relation to laying performance.

2. Predation was higher in BA than HB.

3. Mortality through disease was higher in RIR than BA and HB.

4. Crossbred HB birds show the lowest combination of mortality and predation, suggesting a heterosis effect.

5. Mortality did not differ on farms and in field environments, suggesting an inability to improve biosecurity in farm conditions.

6. There was a positive relationship between eggshell strength and mortality. Calcium depletion from the birds’ bones, limiting foraging and escaping ability may be the explanation, which ultimately increases susceptibility to disease and predation.     

Prevalence and spatial distribution of cattle herds infected with Theileria orientalis in New Zealand between 2012 and 2013

AIM: To describe the prevalence and spatial distribution of cattle herds infected with Ikeda and non-Ikeda types of Theileria orientalis in New Zealand between November 2012 and June 2013.

METHODS: Pooled serum samples collected historically between November 2012 and June 2013 were obtained from cattle herds throughout New Zealand. Each pooled sample consisted of approximately 20 individual cattle samples from that herd, and was provided with details of the spatial location of the herd (n=722). DNA from all samples was tested using two quantitative PCR assays for the detection of T. orientalis (all types) and the Ikeda type. The proportion of herds that were positive for T. orientalis and Ikeda type, or that were positive for T. orientalis but negative for Ikeda type (non-Ikeda positive) was determined for different regions of New Zealand.

RESULTS: The highest prevalence of herds infected with Ikeda type was detected in the Northland (33/35; 94%) and Auckland and the Waikato (63/191; 33%) regions. Only 2/204 (1%) herds were positive for the Ikeda type in the South Island. A high percentage of herds that were positive for non-Ikeda types was detected in the Gisborne and Hawkes Bay (23 (95%CI=13–37)%), Auckland and Waikato (22 (95%CI=16–29)%) and Bay of Plenty (24 (95%CI=10–44)%) regions.

CONCLUSIONS AND CLINICAL RELEVANCE: The high prevalence of Ikeda type detected in cattle herds in the Northland, Auckland and Waikato regions represents a risk to naive cattle being introduced into these regions. There is also the potential for resident cattle herds in the Gisborne and Hawkes Bay, Auckland, Waikato and Bay of Plenty regions to experience increased infection with the Ikeda type.

The overall impact experienced by regions will depend on other factors such as the number of herds present and the predominant type of farming, as well as the interplay between tick ecology, cattle immunity and movement patterns of cattle.     

Effect of diets containing sulfate or chloride-based anionic salts,fed to grazing prepartum dairy cows,on concentrations of Ca in plasma,disease incidence and milk yield

AIMS: To compare the effect of two partial mixed ration diets containing either sulfate or chloride-based anionic salts, fed to grazing prepartum dairy cows, on concentrations of Ca, Mg, P and beta-hydroxybutyrate (BHB) in plasma, disease incidence and milk yield during the early postpartum period.

METHODS: The study was conducted on a seasonal-calving grazing dairy farm located in Benton (MO, USA). In August 2016, two groups of 200 cows were randomly assigned at 30 days before expected parturition to receive either a sulfate or chloride-based anionic diet, to achieve a dietary cation–anion difference (DCAD) of ?25?mEq/kg DM. Cows were fed partial mixed rations to provide 50% of their DM intake, with 50% provided by grazing fescue pasture. Urine samples were collected from 20 cows from each group once a week for 5 weeks until calving for pH assessment. At parturition, 42 cows per group were selected at random and blood samples collected on Days 1, 2, 3 and 7 postpartum. The study continued until 100 cows per group calved. Health events and cumulative milk yield until 30 days postpartum were recorded. Concentrations of Ca, P, and Mg in plasma at Days 1, 2, 3, and 7, and BHB in plasma at Day 7 postpartum were assessed.

RESULTS: Mean urine pH was lower in cows in the chloride than sulfate group (p≤0.06) on four of five sampling occasions. Mean concentrations of Ca in plasma on Day 1 were 2.00 (95% CI=1.94–2.05) and 1.91 (95% CI=1.88–1.97) mmol/L for the chloride and sulfate groups, respectively (p=0.15), and on Day 3 were 2.03 (95% CI=1.97–2.08) and 1.90 (95% CI=1.84–1.96) mmol/L, respectively (p=0.038). Concentrations of Mg, P and BHB in plasma and incidence of diseases postpartum were similar in both groups (p>0.05). There were no cases of clinical hypocalcaemia in either group.

CONCLUSIONS AND CLINICAL RELEVANCE: Prepartum cows fed a partial mixed ration with a negative DCAD containing chloride-based anionic salts and free access to a fescue pasture had lower prepartum urine pH, and higher concentrations of total Ca in plasma during the first week postpartum, than cows receiving a partial mixed ration containing sulfate-based anionic salts.     

Effect of substrate provision on performance and behaviour of laying hens in the pecking and scratching area of furnished cages

1. An experiment was set up to study the effects of substrate provision on performance and behaviour in the pecking and scratching area (PSA) of non-beak-trimmed hens housed in large furnished cages (60 hens/cage).

2. Three layer hybrids (two brown and one white, ISA-Hendrix Genetics, France) and two substrate conditions (with or without wheat bran automatically distributed on the PSA) were compared in a 3 × 2 experimental design with 12 cages per treatment.

3. Substrate distribution improved laying rate with no impact on the frequency of dirty or cracked eggs.

4. Substrate distribution improved the viability and body integrity of hens, which were not beak-trimmed.

5. Distribution of substrate tended to increase the number of hens in the PSA and enhanced their pecking and scratching behaviours but had a negative impact on the number of dust bath bouts per cage and encouraged dust bathing on the wire floor close to the feeder.

6. The white hens laid more eggs in the nest than the brown birds and used the PSA more for pecking, scratching and dust bathing at the end of the day than the brown hens, underlining the necessity to adapt cage furnishing and rearing management to specific behaviours of each layer genotype.     

Factors influencing bacterial eggshell contamination in conventional cages,furnished cages and free-range systems for laying hens under commercial conditions

1.?The aim was to assess eggshell contamination in various laying hen-housing systems and to identify factors influencing this contamination.

2.?Fifty-eight laying hen farms in France were studied, including 21 flocks housed in conventional cages, 7 in furnished cages and 30 kept on-floor.

3.?Sixty eggs per flock were analysed to obtain counts of the total mesophilic flora. Data on equipment and hen management were collected.

4.?Mean bacterial count on eggshells tended to be higher in on-floor systems (4·82 ± 0·51 log CFU/eggshell) than in cage systems (4·57 ± 0·58 log CFU/eggshell, P = 0·09).

5.?Contamination increased with age of the hens, airborne dust concentration, manual packing of the eggs, and packing in plastic rather than in recycled-pulp egg-flats.

6.?The effect of the housing system on eggshell contamination, previously described in experimental assays, was confirmed under production conditions.     

Automated early detection of drops in commercial egg production using neural networks

1. The purpose of this work was to support decision-making in poultry farms by performing automatic early detection of anomalies in egg production.

2. Unprocessed data were collected from a commercial egg farm on a daily basis over 7 years. Records from a total of 24 flocks, each with approximately 20 000 laying hens, were studied.

3. Other similar works have required a prior feature extraction by a poultry expert, and this method is dependent on time and expert knowledge.

4. The present approach reduces the dependency on time and expert knowledge because of the automatic selection of relevant features and the use of artificial neural networks capable of cost-sensitive learning.

5. The optimum configuration of features and parameters in the proposed model was evaluated on unseen test data obtained by a repeated cross-validation technique.

6. The accuracy, sensitivity, specificity and positive predictive value are presented and discussed at 5 forecasting intervals. The accuracy of the proposed model was 0.9896 for the day before a problem occurs.     

A review of the official sampling of flocks of laying hens in the Salmonella National Control Programme in Great Britain

1. In line with European legislation and the UK National Control Programme for Salmonella, poultry farms are sampled to establish their Salmonella status. Regular samples are collected by the farmer (operator), with annual routine (official) samples being collected by the competent authority to verify achievement of the Salmonella programme reduction target.

2. To confirm sampling was being carried out effectively, a questionnaire-based survey was conducted. The aim was to identify any complicating factors the samplers encountered and the decisions made in these circumstances.

3. There was good compliance with the official sampling visits, with few delays reported. However, farm-specific clothing/separate boots for non-caged houses were rarely provided by the operator, whereas boot dips and hand washing facilities were usually available. The collection of dust was often a problem for official samplers, operator boot swabs were not always moistened before sampling and both sampler groups did not always follow the recommended method for the collection of faeces from belts and scrapers.

4. Overall, there was a good application of the sampling protocol, although a few areas for improvement were identified.