Nils Fall

An Observational Study on Early-Lactation Metabolic Profiles in Swedish Organically and Conventionally Managed Dairy Cows

The aim of this observational study was to compare indicators of energy balance in early lactation in organically managed dairy cows (OMC) and conventionally managed dairy cows (CMC) under field conditions. The diets of OMC and CMC differ as a consequence of the rules and principles of organic dairy farming. The study was based on clinical examinations and blood samples from cows within the range from 2 wk prepartum to 6 wk postpartum, collected from 20 organic and 20 conventional dairy farms with 3 visits at each farm. The farms were located in a southeastern area of Sweden and ranged in size from 45 to 120 cows. The blood parameters selected to reflect energy metabolism were nonesterified fatty acids, beta-hydroxybutyrate, glucose, and insulin. At clinical examination body condition score was registered. The shape of the lactation curve in early lactation was modeled to assess potential differences that could explain the blood parameter profiles. The conventionally managed cows increased their milk yield faster than OMC within the first 2 wk of lactation. Blood nonesterified fatty acid concentrations were similar between the management types, but with a tendency of lesser concentrations in OMC, primarily in early lactation. Postcalving beta-hydroxybutyrate concentrations were constantly lesser in OMC during the first 6 wk of lactation. An interaction between season and insulin concentration necessitated stratification on season. During spring the profiles overlapped, but there was a significant difference in the first 4 d post-calving, when organically managed cows had greater insulin concentrations and in d 30 to 34 when conventionally managed cows had greater insulin concentrations. During fall the profiles overlapped completely and there was no significant difference at any point in time. Glucose concentrations tended to decrease slightly postcalving followed by a gradual elevation to a concentration just under the precalving concentration during the study period. Body condition scores decreased slightly over the study period. No differences were found between the management types with regard to glucose concentrations or registered body condition score. In conclusion, the OMC did not show a greater extent of mobilization of body tissue than CMC as expressed by our study variables. Hence, OMC adjusted the production amount according to feed intake.

Reduced likelihood of bovine coronavirus and bovine respiratory syncytial virus infection on organic compared to conventional dairy farms.

Abstract The prevalence of antibodies to bovine coronavirus (BCV) and bovine respiratory syncytial virus (BRSV) infections was studied in 20 conventional and 20 organic dairy herds. The organic farms had produced ‘certified’ milk for at least 2 years. On two occasions, with a 1-year interval, 699 serum samples from 624 peri-parturient cows were tested by ELISA for antibodies to BCV and BRSV. Accompanying data relating to the sampled animals were collected in order to identify potential factors associated with increased antibody prevalence. The antibody prevalence was high at both sampling times with approximately 85% and 80% of animals positive for antibodies to BCV and to BRSV, respectively. Conventional herds had a significantly higher mean antibody prevalence to BCV and BRSV than the organically managed herds (P <0.01). Animal age was significantly associated with increased antibody prevalence (P <0.001). The findings of this study suggest that organic farm management may be effective in reducing the seroprevalence of these viruses relative to conventional farming methods.

Milk yield, udder health and reproductive performance in Swedish organic and conventional dairy herds.

Organic dairy farming is an expanding segment of the dairy sector where cow management differs from the conventional model in many respects. Thus, a comparative evaluation of disease and welfare status in organically and conventionally managed dairy cows is required. Assessment of milk yield, udder health and reproductive performance (RP) was done in 20 organically and 20 conventionally managed Swedish dairy herds. In accordance with earlier findings we confirmed lower milk yield in organic cows. Udder health and RP were chosen as indicators of animal health in view of their clinical relevance and the availability of appropriate data bases providing good background knowledge for further animal health assessment. No obvious differences were found in the investigations of somatic cell count (SCC) profiles or time to veterinary-treated cases of mastitis between organically and conventional managed cows. Pregnancy success at first insemination, an appropriate measurement of RP with biological interpretation and background, did not reveal any difference between management types, whereas the hazard rate-ratio (HR) of having a calving-interval was significantly lower (HR=0.71) in organically managed cows. The calving-interval is an important financial determinator in dairy production, but it is not considered an optimal indicator of biologic relevance as it partially reflects farmer decisions. In conclusion, the organically managed cows in this study did not differ from conventionally managed cows in udder health or RP, with the exception of calving interval.

Fatty acid content, vitamins and selenium in bulk tank milk from organic and conventional Swedish dairy herds during the indoor season.

Fatty acids, vitamins and minerals in milk are important for the human consumer, the calf and the cow. Studies indicate that milk from organic and conventional dairy herds may differ in these aspects. The aim of this study was therefore to investigate whether there are differences in the fatty acid composition and concentration of vitamins and selenium in milk between organic and conventional herds in Sweden. Bulk tank milk was sampled in 18 organic and 19 conventional dairy herds on three occasions during the indoor season 2005-2006. Herd characteristics were collected by questionnaires and from the official milk recording scheme. Multivariable linear mixed models were used to evaluate the associations between milk composition and type of herd, while adjusting for potential confounders and the repeated observations within herd. In addition to management type, variables included in the initial models were housing type, milk fat content, herd size, average milk yield and time on pasture during summer. The median concentration of conjugated linoleic fatty acids (CLA) was 0·63% in organic compared with 0·48% in conventional herds, the content of total n-3 fatty acids was 1·44% and 1·04% in organic and conventional milk, respectively, and the content of total n-6 fatty acids was 2·72% and 2·20% in organic and conventional milk, respectively. The multivariable regression models indicated significantly higher concentrations of CLA, total n-3 and n-6 fatty acids in organic milk and a more desirable ratio of n-6 to n-3 fatty acids, for the human consumer, in organic milk. The multivariable models did not demonstrate any differences in retinol, α-tocopherol, β-carotene or selenium concentrations between systems. Median concentrations of α-tocopherol were 0·80 μg/ml in organic and 0·88 μg/ml in conventional milk, while for β-carotene the median concentrations were 0·19 and 0·18 μg/ml, respectively; for retinol, the median concentration was 0·32 μg/ml in both groups; the median concentrations of selenium were 13·0 and 13·5 μg/kg, respectively, for organic and conventional systems.

Exposure to pasture borne nematodes affects individual milk yield in Swedish dairy herds

The association between exposure to gastrointestinal nematode (GIN) parasitism, indicated by elevated individual optical density ratio (ODR) to Ostertagia ostertagi, and individual milk production was analysed in dairy cows. The multivariable analysis also accounted for other sources of variation than exposure to GIN parasitism. Intra- and inter-herd variation in parasite exposure was also evaluated. Organic and conventional herds located in south-east Sweden (13 herds per system) were visited during the housing period 2009-2010. Levels of all major pasture-borne helminths in Sweden (O. ostertagi, Fasciola hepatica and Dictyocaulus viviparus) were determined in bulk tank milk, cow milk and serum (only for O. ostertagi). Their specific antibodies were detected using three different ELISAs (Svanova Biotech) and the optical density of the sample was expressed as ODR. Positive cases of Dictyocaulus and Fasciola were seldom found. Variation in ODR in serum samples for Ostertagia was higher within herds than between herds. Correlations between ODR for Ostertagia in serum and milk parameters were significant and negative. In the multivariable analysis, two models were performed separating data from primiparous and multiparous cows. Results from mixed models showed that daily milk yield was significantly influenced by Ostertagia ODR for multiparous cows. No interactions were found between Ostertagia ODR values and herd type.

Pathological and bacteriological characterization of neonatal porcine diarrhoea of uncertain aetiology

Neonatal porcine diarrhoea of uncertain aetiology has been reported from a number of countries. This study investigated 50 diarrhoeic and 19 healthy piglets from 10 affected Swedish herds. The piglets were blood-sampled for analysis of serum γ-globulin and necropsied, and the intestines were sampled for histopathology and cultured for Escherichia coli, Clostridium perfringens and Clostridium difficile. Escherichia coli isolates (n = 276) were examined by PCR for virulence genes encoding LT, STa, STb, EAST1, VT2e, F4, F5, F6, F18, F41, AIDA-I, intimin, and for the genes aaiC and aggR. Selected isolates were analysed for additional virulence genes by a microarray and subjected to O-typing. Clostridium perfringens isolates (n = 152) were examined by PCR for genes encoding major toxins, enterotoxin and beta2-toxin. There was no difference in serum γ-globulin concentration between diarrhoeic and non-diarrhoeic piglets, and pathological lesions in the intestines were generally mild. Porcine enterotoxigenic Escherichia coli, a common cause of piglet diarrhoea, was only found in two piglets. Further, the virulence gene profiling did not suggest involvement of other diarrhoeogenic pathotypes of Escherichia coli. Growth of Clostridium perfringens did not differ between diarrhoeic and non-diarrhoeic piglets. All isolates were type A, all were negative for enterotoxin, and 151 of 152 isolates were beta2-toxin positive. In pigs ≥ 2  days old, moderate to profuse growth of Clostridium difficile was more common in the controls. In conclusion, it was not possible to relate Escherichia coli, Clostridium perfringens type A and C or Clostridium difficile to neonatal porcine diarrhoea in any of the investigated herds.

Bovine respiratory syncytial virus and bovine coronavirus in Swedish organic and conventional dairy herds

BackgroundInfections with bovine respiratory syncytial virus (BRSV) and bovine coronavirus (BoCV) are endemic to the cattle populations in most countries, causing respiratory and/or enteric disease. It has been demonstrated that herds can remain free from these infections for several years also in high prevalence areas. Organically managed (OM) dairy herds have been shown to have lower seroprevalence of both viruses compared to conventionally managed (CM) herds. The objective of this study was to challenge the hypothesis of a lower occurrence of BRSV and BoCV in OM compared to CM dairy herds.In November 2011, May 2012 and May 2013 milk samples from four homebred primiparous cows were collected in 75 to 65 OM and 69 to 62 CM herds. The antibody status regarding BRSV and BoCV was analysed with commercial indirect ELISAs. Herds were classified as positive if at least one individual sample was positive.ResultsThe prevalence of positive herds ranged from 73.4% to 82.3% for BRSV and from 76.8% to 85.3% for BoCV among OM and CM herds, over the three sampling occasions. There was no statistically significant difference between OM and CM herds at any sampling occasion. The incidence risk of newly infected herds did not differ statistically between OM and CM herds at any sampling occasion, neither for BRSV nor for BoCV. The incidence of herds turning sero-negative between samplings corresponded to the incidence of newly infected. Bulk tank milk (BTM) samples were also sampled in the herds and analysed. Several herds were negative on individual samples but positive in BTM. Herd-level data on production, health and reproduction were retrieved from VÄXA Sweden and the study herds were representative of the source population.ConclusionThere was no difference in prevalence of or incidence risk for BRSV or BoCV between Swedish OM and CM herds. Because the incidence of herds becoming seropositive was balanced by herds becoming seronegative it should be possible to lower the prevalence of these two infections among Swedish dairy cattle herds if biosecurity is improved.

Comparison of Bovine coronavirus–specific and Bovine respiratory syncytial virus–specific antibodies in serum versus milk samples detected by enzyme-linked immunosorbent assay

Bovine coronavirus (BCV; Betacoronavirus 1) and Bovine respiratory syncytial virus (BRSV) are significant causes of enteric and respiratory disease in beef and dairy cattle throughout the world. Indirect enzyme-linked immunosorbent assays are widely used to detect serum antibodies for herd monitoring and prevalence studies. In dairy herds, milk is more readily collected than serum. Hence, in order to investigate the test agreement between serum and milk, both serum and milk samples from 105 cows in 27 dairy herds were analyzed in parallel for presence of immunoglobulin G antibodies to BCV and BRSV. The Bland–Altman analyses of data demonstrated good agreement between serum and milk antibody titers for both viruses. The results indicate milk samples are sufficient for surveillance of antibodies to BCV and BRSV.

Exploring milk shipment data for their potential for disease monitoring and for assessing resilience in dairy farms

Abstract The use of routinely recorded data for research purposes and disease surveillance is an attractive proposition. However, this requires that the validity and reliability of the data be evaluated for the purpose for which they are to be used. This manuscript reports an evaluation of milk shipment data for evaluating their usefulness in disease monitoring and the resilience of organic and conventional dairy herds in Sweden. A large number of inconsistencies were observed in the data, necessitating substantial efforts to “clean” the data. Given that the selection of rules used in the cleaning process was subjective in nature, a sensitivity analysis was carried out to determine if different cleaning routines produced substantially different results. Despite the cleaning efforts we observed far more large residuals at the shipment level than expected. Thus, it was concluded that the data were too “noisy” to be used for identification of short term impacts on milk production. Resilience was evaluated by examining the residual variance in milk shipped per cow per day under the assumption that herds with high resilience would have lower residual variance. The effects on residual variance of organic status or whether or not the herd used an automatic milking system were evaluated in models in which the residual variance was stratified or not by these factors. We did not find consistent evidence to suggest that organic herds had higher resilience than conventional herds, but this could be partly due to using residual variance as the measure indicating resilience.

Biosecurity and animal disease management in organic and conventional Swedish dairy herds: a questionnaire study

BackgroundGood animal health is a notion that is germane to organic dairy production, and it is expected that such herds would pay significant attention on the health of their animals. However, it is not known if the applied animal disease management is actually more adequate in organic dairy cattle herds than in conventional dairy herds. A questionnaire study on biosecurity and animal disease management activities was therefore conducted among Swedish farmers with organic and conventional dairy cattle herds.ResultsA total of 192 useable questionnaires were returned; response rates of 30.3 and 20.2% for organic and conventional farmers, respectively. Herd characteristics of the two herd types were very similar, except that pipeline/tie-stall systems were less common in organic farms and that organic farmers had a higher education level than their conventional counterparts. Also, very few systematic differences in general or specific disease management activities were observed between the two types of farms. The main exceptions being how milk from cows during antibiotic treatment was used, views on policy actions in relation to antibiotic use, and attitudes towards calling for veterinary support. Using milk from cows during antibiotic treatment was more common in conventional herds, although it was mainly given to bull calves. Farmers of organic herds were more positive to policy actions to reduce the use and need for antibiotics, and they reported waiting longer before contacting a veterinarian for calves with diarrhoea and cows with subclinical mastitis.ConclusionsThe stated biosecurity and animal disease management was relatively equal in Swedish organic and conventional dairy herds. Our results thus indicate that animal health is as important in conventionally managed dairy herds in Sweden as in organically managed herds.