Training of transport drivers improves their handling of pigs during loading for transport to slaughter.

Pig transport drivers' (TDs') handling actions are of great importance as these drivers handle a large number of finishing pigs during stressful situations. Poor handling techniques can have negative consequences for working conditions, pig welfare and meat quality. We studied the effects of a training intervention on Swedish TDs' attitudes towards pigs and their handling actions during loading for transport to slaughter. Twenty TDs working with commercial pig transportation in Sweden were recruited and completed an attitude questionnaire. Ten of them were observed during one loading of pigs before training, and one or two loadings after training (49-265 pigs per loading), and eight of them completed the attitude questionnaire again 50-160 days after training. The cognitive-behavioural training program ProHand Pigs® was adapted and delivered to the ten TDs during a group session, followed by individual meetings. TDs' handling actions were video recorded and summarised as binary variables per 5-s interval. Factor analysis, principal component analysis and paired t-test were conducted to investigate the effects of the training intervention on TDs' attitudes, and mixed-effects logistic models were used to examine effects on negative and positive handling actions. Training tended to decrease TDs' beliefs that it is important to move pigs quickly (P = 0.095). Training decreased the odds of a 'moderately to strongly negative' action by 55% (P = 0.0013) and increased the odds of a 'positive' action by 97% (P < 0.0001). This study provides valuable insights into the possibilities to improve TDs' handling actions, and implications for pig welfare during slaughter transport. The study supports previous findings that the attitudes and behaviour of handlers can be improved by cognitive-behavioural training. While our previous research has shown reciprocal relationships between TDs' actions and pig behaviour, further research on TDs' attitudes towards handling that underlie the nature of their behaviour when handling pigs is necessary to fine-tune the cognitive-behavioural training program applied in the present study.

An epidemiological analysis of equine welfare data from regulatory inspections by the official competent authorities.

Determining welfare status in a population is the first step in efforts to improve welfare. The primary objective of this study was to explore a new epidemiological approach for analysis of data from official competent authorities that pertain to compliance with animal welfare legislation. We reviewed data already routinely collected as part of Swedish official animal welfare inspections for 2010-13, using a checklist containing 45 checkpoints (CPs). These covered animal-, resource- and management-based measures of equine welfare. The animal-based CPs were measures that directly related to the animal and included social contact, body condition, hoof condition and cleanliness. Non-compliance with one or more of the animal-based CPs was used as a binary outcome of poor equine welfare; 95% confidence intervals (CI) were estimated using the exact binomial distribution. Associations were determined using multivariable logistic regression, adjusting for clustering on premises. Resource- and management-based CPs (model inputs) were reduced by principal component analysis. Other input factors included premises characteristics (e.g. size, location) and inspection characteristics (e.g. type of inspection). There were 30 053 premises with horses from 21 counties registered by the Swedish Board of Agriculture. In total 13 321 inspections of premises were conducted at 28.4% (n=8532) of all registered premises. For random inspections, the premises-prevalence of poor equine welfare was 9.5% (95% CI 7.5, 11.9). Factors associated with poor equine welfare were non-compliance with requirements for supervision, care or feeding of horses, facility design, personnel, stable hygiene, pasture and exercise area maintenance, as well as the owner not being notified of the inspection, a previous complaint or deficiency, spring compared with autumn, and not operating as a professional equine business. Horses at premises compliant with stabling and shelter requirements had significantly better welfare if they also complied with documentation requirements. We present a novel approach for analysis of equine welfare data from regulatory inspections by the official competent authorities, and propose on-going analyses and benchmarking of trends in animal-based measures over time. We also suggest how such a database could be further improved to facilitate future epidemiological analyses of risk factors associated with poor equine welfare. The study has implications for other competent authorities and researchers collaborating in the area of animal welfare epidemiology.

Influence of strain and parity on the risk of litter loss in laboratory mice.

Pup mortality is a considerable problem in laboratory mouse breeding and the view that parity influence survival of newborn mice is widespread. Some evidence suggests that maternal behaviour is related to offspring mortality in mice. Parental experience is a factor that can improve maternal behaviour and offspring survival in some mammals. However, few papers report a relationship between parity and pup survival in mice. We investigated the influence of strain and parity on loss of entire litters of C57BL/6 and BALB/c mice using data from a breeding colony. In total, 344 C57BL/6 and 146 BALB/c litters were included. We found a considerable mortality rate for both strains: 32% of C57BL/6 litters and 20% for BALB/c litters were lost. There was a significant difference in survival of the first litter between strains, with 3.6 times higher odds of mortality in C57BL/6 mice (p = 0.0028). Parity or previous parental experience of litter loss did, however, not affect litter loss. The scientific literature does not provide a clear picture of perinatal mortality in laboratory mice. Very few studies report perinatal mortality, and only a handful of papers exist where mortality was systematically studied; this area is thus poorly understood. If perinatal mortality in mice is not recognized and investigated, but instead considered normal when breeding mice, a serious welfare problem might be overlooked.

Risk factors for displaced abomasum or ketosis in Swedish dairy herds.

Risk factors associated with high or low long-term incidence of displaced abomasum (DA) or clinical ketosis were studied in 60 Swedish dairy herds, using multivariable logistic regression modelling. Forty high-incidence herds were included as cases and 20 low-incidence herds as controls. Incidence rates were calculated based on veterinary records of clinical diagnoses. During the 3-year period preceding the herd classification, herds with a high incidence had a disease incidence of DA or clinical ketosis above the 3rd quartile in a national database for disease recordings. Control herds had no cows with DA or clinical ketosis. All herds were visited during the housing period and herdsmen were interviewed about management routines, housing, feeding, milk yield, and herd health. Target groups were heifers in late gestation, dry cows, and cows in early lactation. Univariable logistic regression was used to screen for factors associated with being a high-incidence herd. A multivariable logistic regression model was built using stepwise regression. A higher maximum daily milk yield in multiparous cows and a large herd size (p=0.054 and p=0.066, respectively) tended to be associated with being a high-incidence herd. Not cleaning the heifer feeding platform daily increased the odds of having a high-incidence herd twelvefold (p<0.01). Keeping cows in only one group in the dry period increased the odds of having a high incidence herd eightfold (p=0.03). Herd size was confounded with housing system. Housing system was therefore added to the final logistic regression model. In conclusion, a large herd size, a high maximum daily milk yield, keeping dry cows in one group, and not cleaning the feeding platform daily appear to be important risk factors for a high incidence of DA or clinical ketosis in Swedish dairy herds. These results confirm the importance of housing, management and feeding in the prevention of metabolic disorders in dairy cows around parturition and in early lactation.

Perceived physical and psychosocial exposure and health symptoms of dairy farm staff and possible associations with dairy cow health.

The aim of this study was to gain a deeper understanding of work-related physical and psychosocial exposure and health symptoms of farm staff working in indoor loose-housing dairy systems in Sweden, and to examine possible associations between exposure and health symptoms of farm staff and disease incidence in their dairy herds. A sample of 41 farm owners or managers and 20 directly employed farm workers participated, each from a Swedish dairy farm with loose-housed cows. Mailed questionnaires comprising 29 questions were used to create four separate indices representing physical exposure, psychosocial exposure, physical symptoms, and psychosocial symptoms. Cow herd incidence rates of common veterinary-reported clinical diseases were calculated based on official records. Partial Spearman rank correlation was used to analyze associations. The study confirmed that physical and psychosocial exposure and health symptoms are not uncommon among owners/managers and employed workers. The study also found that farm owners/managers experience more physical symptoms in dairy herds with lower cow disease incidence rates, while more frequent or intensive exposure to negative psychosocial work environment factors among employed dairy workers is associated with a high herd disease incidence rate.

Blood profiles in dairy cows with displaced abomasum.

An observational study was carried out in Swedish dairy herds to investigate differences between cows with and without displaced abomasum (DA), in concentrations of glucose, insulin, fructosamine, nonesterified fatty acids (NEFA), ß-hydroxybutyrate, cholesterol, haptoglobin, increased enzyme activity of aspartate aminotransferase and glutamate dehydrogenase, and the revised Quantitative Insulin Sensitivity Check Index (RQUICKI). A secondary aim was to study how blood profiles for DA cows vary with time in relation to calving. Sixty-nine DA cows within 2 to 56 d postpartum, in 60 herds, were clinically examined and blood samples were drawn at the time DA was diagnosed. At the same time, 104 healthy control cows matched by herd and stage of lactation were also sampled. The blood parameters were studied using mixed linear models, including herd as a random effect, and DA (case or control), parity, breed, sampling time in relation to calving, other diseases, and the interaction between DA and time as fixed effects. Concentrations were higher in DA cows than in control cows for NEFA (least squares means 1.36 vs. 0.34 mmol/L), ß-hydroxybutyrate (1.56 vs. 0.90 mmol/L), aspartate aminotransferase (1.96 vs. 0.97 µkat/L), glutamate dehydrogenase (197 vs. 78 µkat/L), and haptoglobin (0.76 vs. 0.17 g/L), whereas concentrations were lower in DA cows than in control cows for insulin (3.61 vs. 8.48 mU/L) and cholesterol (3.04 vs. 3.75 mmol/L). Glucose (2.83 vs. 2.79 mmol/L) and fructosamine (266 vs. 252 µmol/L) concentrations were similar in both groups; however, a tendency toward lower RQUICKI values (0.42 vs. 0.46) in the DA cows was found, indicating reduced insulin sensitivity. For most blood parameters, differences between DA cows and controls remained constant over time. Seventy-two percent of the DA cows had at least one other disease in the period from 1 wk antepartum to 1 wk after the DA was diagnosed. Haptoglobin could potentially be used to detect treatable infectious or inflammatory conditions in the early postpartum period, possibly reducing the incidence of DA. Consequently, there were major changes in blood profiles in cows with DA compared with healthy control cows, indicating a negative energy balance, liver cell damage, and an inflammatory response. The results contribute to an understanding of the metabolic changes in DA cows.

Calving interval in dairy cows in relation to heifer rearing conditions in southwest Sweden.

Sustained reproductive performance throughout the life of domestic animals can be suspected to require successful rearing of replacements. We studied associations between replacement heifer rearing conditions and reproductive performance throughout the productive life of dairy cows in southwest Sweden by linear mixed modelling. Data consisted of 3542 lactations in 1550 Swedish Reds, Swedish Holsteins or dairy cows of other or mixed breeds, representing all female animals born during 1998 in 107 herds. Median calving interval (CI) was 381, 380 and 377 days in parities 1, 2 and > or =3, respectively. Median observed productive lifetime was 27 months. The applied model included effects of cow housing system, breed, parity, respiratory disease before 3 months of age, whether oestrous detection was performed only at feeding, oestrous-detection ability, calving year, post-calving reproductive disease in a given lactation, milk yield 30 days post-calving relative to the herd mean, the interaction of breed by calfhood respiratory disease and random effects of cow and herd. Severe respiratory disease before 3 months of age in Swedish Red cows was associated with an increase in CI by 12%. Of the total variation in CI, 9.5% was due to herd factors and 12% to cow factors, as opposed to variation between lactations.

Lifetime risk and cost of clinical mastitis in dairy cows in relation to heifer rearing conditions in southwest Sweden.

Relationships between heifer rearing conditions and the risk of veterinary-reported clinical mastitis (VRCM) during productive life were studied by generalized linear mixed modeling at the lactation level. Data consisted of 5,693 lactations in 2,126 Swedish Reds, Swedish Holsteins, or dairy cows of other or mixed breeds, representing all female animals born in 110 herds in southwest Sweden in 1998. During a lactation, a cow was defined as affected by VRCM if one or more cases were reported by a veterinarian, starting from 7 d precalving. The applied model of VRCM included effects of breed, parity, diarrhea between 3 and 7 mo of age, increase in body weight from weaning to first breeding, increase in daily concentrate ration before first calving, herd-level median age at first calving, cow housing, and random effects of cow and herd. The VRCM incidence was 14% in a given lactation, or 0.11 cases/cow annually; 31% of the cows had VRCM at least once during their productive life. Ninety percent of the variation in mastitis risk was due to factors at the lactation level such as parity, milk yield, cow diseases, and other disturbances, instead of cow or herd factors. Severe diarrhea between 3 and 7 mo of age was associated with 2.8-fold higher odds of VRCM compared with mild diarrhea during the same period, whereas the VRCM odds of calves with mild diarrhea were half that without diarrhea. The odds of VRCM had a predicted maximum at an estimated prepubertal growth rate of 859 g/d and increased with 10% for every 1-kg increase in concentrate ration during the last 2 mo before first calving. Costs of VRCM were estimated based on assumptions regarding veterinary service, extra labor, culling and herd replacement, discarded milk, and production loss depending on parity and lactation stage when VRCM was diagnosed. The total mean costs of VRCM were estimated to be $735 per lactation with a diagnosis of CM, $103 per lactation across all cows, or $95 per cow annually during lifetime.

Associations between housing, management, and morbidity during rearing and subsequent first-lactation milk production of dairy cows in southwest Sweden.

Information regarding health, management, and housing from birth to first calving was collected for 1,029 Swedish Reds, 991 Swedish Holsteins, and 40 heifers of crossbreed or other breeds on bimonthly farm visits made by 3 project veterinarians to 107 dairy herds in southwest Sweden. Additional data were obtained from the official milk- and health-recording program. Milk production at first test day after calving [energy-corrected milk (ECM)1] and during the first 305 d of lactation (ECM305), respectively, were analyzed by 2-level (animal; herd) linear regression, after initial screening by univariable analyses of 67 potentially important predictors. The ECM1 ranged from 7.9 to 48.0 (median = 27.1) kg, and ECM305 ranged from 3,764 to 12,136 (median = 8,006) kg. In the final models, factors associated with ECM1 or ECM305 or both were age at first calving, body condition score at first service, breed, calfhood diarrhea, calving season, composite somatic cell count at first test day, daily weight gain from weaning to first service, housing system after calving, and increase in concentrate fed around calving. Higher age at calving was associated with higher production. Production also increased with higher daily weight gains from weaning to first service. Swedish Holsteins produced more than Swedish Reds, cows calving in May to September produced more than those calving during other months, and cows housed in short stalls after calving produced more than those in cubicles. Body condition scores > or =3.2 at first service were associated with lower ECM305 than scores < or =2.9. Animals that contracted mild diarrhea during their first 3 mo of life had lower ECM305 than animals without diarrhea, whereas animals receiving a high increase in concentrate pre- and postcalving had higher ECM305 than those subjected to a more moderate increase. Cows with a composite somatic cell count >1 million cells/milliliter at first test day produced less milk on the same day than cows with lower counts. It was concluded that rearing factors and calfhood health status can influence first lactation milk production.

Evaluating the efficacy of serum haptoglobin concentration as an indicator of respiratory-tract disease in dairy calves.

The serum concentration of haptoglobin (S-Hp) was measured in 833 group-housed dairy calves from nine herds in south-west Sweden once at 24-56 days of age to evaluate the potential of S-Hp as an indicator of clinical respiratory-tract disease (CRD). Presence of disease (treated and non-treated) was assessed clinically by farmers and by a project veterinarian visiting the farms every third week. The median S-Hp of healthy calves was 0.06g/L (80% central range: 0.04-0.23), of calves with diarrhoea within the 10 days before sampling 0.07g/L (80% central range: 0.04-0.63), and of calves with CRD within the 14 days before sampling 0.09g/L (80% central range: 0.04-0.69). Eight different cut-off values were used to define a positive S-Hp analysis result: >0.05, >0.06, >0.07, >0.08, >0.09, >0.10, >0.15 and >0.20g/L. A rectal temperature >39.5 degrees C was denoted as fever. A positive result of five different diagnostic tests for CRD was defined as: (1) a positive S-Hp with fever absent, (2) a positive S-Hp with fever present, (3) either a positive S-Hp or fever, (4) both a positive S-Hp and fever, and (5) fever (regardless of S-Hp). The sensitivity (Se) and specificity (Sp) of each test were calculated from regression coefficients of generalized linear mixed models of the binary test results, applying a logit link. Apart from CRD status (within the 14 days before sampling; no or yes), the models included sex (bull or heifer), and for the test based on S-Hp alone, also rectal temperature (fever, no or yes). Confidence intervals (CI) of Se and Sp were estimated by simulation. Based on Se, Sp, and areas under Receiver Operating Characteristics curves, test 3 was considered the best. At optimal performance, giving equal importance to type I and II errors, i.e. at a S-Hp cut-off of 0.15g/L in heifer calves, Se was 0.64 (95% CI 0.50-0.77) and Sp 0.71 (95% CI 0.60-0.80), and at a S-Hp cut-off of 0.08g/L in bulls, Se was 0.52 (95% CI 0.40-0.64) and Sp 0.80 (95% CI 0.74-0.85). The other tests were judged as unsatisfactory indicators of CRD. In heifers, the proportion of CRD-positive calves in the herd was strongly associated with the proportion of test positives (S-Hp or fever; S-HP and fever), suggesting potential as a herd-level indicator.

Morbidity in 3-7-month-old dairy calves in south-western Sweden, and risk factors for diarrhoea and respiratory disease.

The health status of 2947 heifer calves born in 1998 and raised in 122 Swedish dairy herds was monitored from birth to 210 days of age. Disease occurrence was recorded by farmers and by veterinarians who visited the farms six times yearly, examined the calves clinically and auscultated their lungs. The incidence risks of diarrhoea, ringworm and clinical respiratory-tract disease (CRTD) in calves from 3 to 7 months of age were 2.7%, 5.6% and 5.7%, respectively. The herd-level incidence risks of the three diseases were zero in 63.1%, 76.2% and 48.4%, respectively, of the herds. In positive herds incidence risks were 2.2-46.4%, 2.6-47.0% and 2.2-53.3%, respectively. The associations between the potential risk factors age at first grazing, air quality, birth place, feeding of colostrum, hygiene, number of animals, age range within the pen or building, pen area, pen location, previous housing type, present housing type, previous disease and season, and each of three binary outcome variables (diarrhoea, increased respiratory sounds and CRTD) were evaluated using two-level (calf; herd) variance component logistic models. Predictors significantly associated (P<0.05) with diarrhoea were pen area, season and the interaction between pen location and previous CRTD. Previous CRTD, season and heart girth at weaning were significantly associated with moderately to severely increased respiratory sounds. Predictors significantly associated with CRTD were previous diarrhoea, previous housing and season. It was concluded that the incidence of diarrhoea and CRTD in 91-210-day-old Swedish dairy calves is higher than previously reported from dairy herds in Sweden and the USA, and that diarrhoea, increased respiratory sounds and CRTD are associated with season, a history of disease during the first 90 days of age and, to some extent, housing factors.

Effects of a rubber-slatted flooring system on cleanliness and foot health in tied dairy cows.

Effects on animal cleanliness and foot health of a new rubber-slat system for tied dairy cows, with the ability to drain faeces and urine, were studied in a 2-year controlled quasi-randomised trial in a Swedish university herd. Swedish Red and White cows were kept tied in 42 traditional long-stalls with rubber mats. In total, 82 cows were observed. In 21 stalls, the rearmost 0.74m of the solid stall floor was replaced with nine rubber-coated 53mm wide slats, divided by 29mm slots. The cleanliness was assessed subjectively weekly (year 1) or bi-weekly (year 2) by observations of the hind part of the body. Claw measurements and foot health in hind feet were assessed in connection with hoof trimmings at the beginning, middle and end of the housing period. The foot-health recordings were blinded to flooring. For the analysis of both cleanliness (1781 records, 73 cows) and foot health (240 records, 79 cows), logistic regression was applied, using marginal models and cow observations as repeated measures within each year. The risk of getting dirty on the rubber-slatted floor was significantly lower (odds ratio 0.12 for hind feet when short stall dividers were used, 0.39 for hind legs and 0.38 for thighs and udder), comparing with the solid stall floor. The prevalence of foot diseases in hind feet at trimming was significantly lower on the rubber slats (odds ratio 0.23 for dermatitis, 0.09 for heel horn erosion, and 0.34 for sole ulcer or sole or white line haemorrhage).

Effects of two stall flooring systems on the behaviour of tied dairy cows.

Effects on dairy cow behaviour of a new type of flooring in tie-stalls, with the ability to drain faeces and urine, was studied in a controlled randomised trial in one Swedish university herd. Forty-two Swedish Red and White cows were kept tied in traditional long-stalls (2.20m). In 21 stalls (one stall row), the rearmost 0.74m of the solid stall floor had been replaced with nine rubber-coated 53mm wide slats, divided by 29mm slots. Stalls with rubber slats were equipped with 20mm ethyl-vinyl-acetate (EVA) mats in the front part and littered with 0.7kg of wood shavings daily, while stalls with a solid floor had standard rubber mats and received 3kg of chopped straw daily as bedding. Behaviour was compared between the two stall types, using video recordings of 12 matched pairs of cows for two complete 24h periods each. Statistical analysis was done using the Student's t-test for matched pairs or the sign test. Cows on the rubber slatted flooring lie down and rise normally and without any increased risk of slipping. They lay down more comfortably, i.e. spent on an average 23% less time preparing to lie down, and slipped less frequently during rising. There was some evidence of a preference for a solid floor when lying.

Associations between use of electric cow-trainers and clinical diseases, reproductive performance and culling in Swedish dairy cattle.

The aims of this follow-up study were: (a) to evaluate the role of ECT technology as a risk factor for several diseases; and (b) to determine if the effects of these diseases on cows' reproductive performance and as risk factors for culling are influenced by exposure to ECTs. Diseases considered were retained placenta, metritis, ketosis, cystic ovaries, silent heat, milk fever, clinical mastitis, and foot and leg problems. We used historical and contemporary controls (with control herds selected to match the experimental herds for size and location). Data consisted of 10,264 Swedish Red and White (SRB) and 5461 Swedish Friesian (SLB) lactation records in 150 herds of which 33 used cow-trainers. Logistic regression was used to estimate the effects of parity and exposure to electric cow-trainers on the risks of diseases and the effects of diseases and exposure to electric cow-trainers on risk of culling. The least-squares procedure was used to estimate the effects of diseases on reproductive performance. The dominant effects associated with use of electric cow-trainers were an increased risk for silent heat, clinical mastitis, ketosis and culling relative to cows in herds not using cow-trainers. Diseases had negative effects on reproductive performance and the effects were larger for cows in herds using cow-trainers. In herds using electric cow-trainers, the largest increase in the interval from first service to conception (58 days) was caused by the occurrences of silent heat, cystic ovaries and the combination of two or more diseases. Retained placenta, metritis, cystic ovaries, clinical mastitis and a combination of two or more diseases increased the risk of culling about two times relative to healthy primiparous cows with the increase being greater for cows in herds using cow-trainers. Silent heat did not increase risk of culling in control groups, but was the largest risk factor for culling in the exposed group. We concluded that exposure to electric cow-trainers increased the incidence risk of silent heat, clinical mastitis, and ketosis and changed silent heat from a neutral disease with respect to culling to a major risk factor. Finally, exposure to cow-trainers increased the general negative effect of diseases on the cows' reproductive performance and risk for culling.

Dose response and time course of carboplatin-induced micronucleated polychromatic erythrocytes in the cat: implications for combination carboplatin chemotherapy.

The dose response and time course of micronucleated polychromatic erythrocytes (mPCE) in cat peripheral blood induced by various doses (150-250 mg/m2) of carboplatin in vivo was determined. The data indicate that carboplatin produced a significant (p < 0.05) dose-dependent increase in the number of mPCE over baseline values; however, the times following carboplatin administration when mPCE were first observed differed significantly (p < 0.05) between the three carboplatin dose groups. mPCE were present in significantly greater numbers (p < 0.05) on smears at an earlier time interval following a single carboplatin dose of 150 mg/m2 than for a dose of either 200 or 250 mg/m2. The peak number of mPCE occurred on days 7, 14 and 17.5 following administration of a carboplatin dose of 150, 200 and 250 mg/m2, respectively. The pattern of time course delay following carboplatin administration suggests that the block of erythropoietic stem cells in G2 is dose dependent. Indeed, the administration of carboplatin arrested the cell cycle in the G2 phase and, at higher doses, diminished the number of cycling erythroid precursor cells. mPCE were apparent in blood smears only after recovery from this arrest and resumption of replication. This observation has implications for the scheduling of carboplatin administration when used in combination with other anticancer drugs.

A preliminary study of behavioural methods for assessing the influence of electric cow-trainers on animal health.

Various behavioural patterns were assessed for their usefulness in analysing any possible effects of electric cow-trainers on the health of dairy cows. Four cows in a commercial herd were used, which had not previously been exposed to cow-trainers. Two of these were exposed to conventionally installed and managed cow-trainers and two were controls. It was concluded that preparation to lie down, lying-down movements and comfort behaviour are suitable for the study of relationships between the use of electric cow-trainers and impaired health in cows.

Small electric currents affecting farm animals and man: a review with special reference to stray voltage. I. Electric properties of the body and the problem of stray voltage.

The literature on the electrical properties of the body and sensitivity to steady electric current in humans and farm animals is reviewed and the problem of stray voltage is examined. Stray voltage poses a problem to animal health and protection in cattle and pigs and possibly also in other animals. Dairy cattle can perceive alternating currents exceeding 1 mA between the mouth and all four hooves. Behavioural effects in cows usually occur above 3 mA. In practice, the major influence on dairy cows appears to be behavioural. In experimental research on sensitivity to electric current, the effects studied should be related primarily to the actual current densities or electric fields in the affected tissues rather than to the total voltages applied. Under normal conditions, herdsmen are less likely to be affected by stray voltage than their animals.

Small electric currents affecting farm animals and man: a review with special reference to stray voltage. II. Physiological effects and the concept of stress.

The literature on the influence of small, steady electric currents on animal health, especially cardiovascular and endocrinological functions and milk let-down, and the effects on milk production is reviewed, with special reference to the problem of stray voltage. Direct physiological effects in cows may occur above 4 mA. How the long-term effects may contrast with the acute effects is not known. Habituation may occur. The altered behaviour and physiological changes due to exposure to stray voltage may be termed a stress response. The type of stress most likely to be encountered is chronic. Whether or not stress occurs depends on the timing and context of exposure and on individual cognition. Hence stray voltage may threaten farm animal health and production wherever modern animal housing is applied.