Descriptive evaluation of a camera-based dairy cattle lameness detection technology.

Lameness in dairy cattle is a clinical sign of impaired locomotion, mainly caused by painful foot lesions, compromising the US dairy industry's economic, environmental, and social sustainability goals. Combining technology and on farm data may be a more precise and less labor-intensive lameness detection tool, particularly for early detection. The objective of this observational study was to describe the association between average weekly autonomous camera-based (AUTO) locomotion scores and hoof trimming (HT) data. The AUTO data were collected from 3 farms from April 2022 to March 2023. Historical farm HT data were collected from March 2016 to March 2023 and used to determine cow lesion history and date of HT event. The HT events were categorized as a regular HT (TRIM; n = 2290) or a HT with a lesion recorded (LESION; n = 670). Events with LESION were sub-categorized based on lesion category: digital dermatitis (DD; n = 276), sole ulcer (SU; n = 79), white line disease (WLD; n = 141), and other (n = 174). The data also contained the leg of the LESION, classified as front left (FL; n = 54), front right (FR; n = 146), rear left (RL; n = 281), or rear right (RR; n = 183) leg with 6 events missing the leg. Cows' HT histories were classified as follows: cows with no previous recorded instance of any lesion were classified as TRIM0 (n = 1554). The first instance of any hoof lesion was classified as LESION1 (n = 238). This classification was retained until a subsequent TRIM occurred - recorded as TRIM1 (n = 632). The next unique instance of any lesion following a TRIM1 was classified as LESION2 (n = 86). Any LESION events occurring after LESION1 or LESION2 without a subsequent TRIM were considered a hoof lesion recurrence and classified as LESIONRE1 (n = 164) and LESIONRE2 (n = 22), respectively. TRIM events after LESION2 or LESION2RE (n = 104) or LESION events after LESIONRE1 or LESIONRE2 were classified as LESION_OTHER (n = 160). The AUTO scores from -28 to -1 days prior to the HT event were summarized into weekly scores and included if cows had at least 1 observation per week in the 4 weeks before the event. For all weeks, LESION cows had a higher median AUTO score than TRIM cows. Cows with TRIM0 had the lowest and most consistent median weekly score compared to LESION and other TRIM classifications. Before HT cows with TRIM0 and TRIM1, both had median score increases of 1 across the 4 weeks, while the LESION categories had an increase of 4 to 8. Scores increased with each subsequent LESION event compared to the previous LESION event. Cows with SU lesions had the highest median score across the 4 weeks, WLD had the largest score increase, and DD had the lowest median score and score increase. When grouping a LESION event by leg the hoof lesion was found on, the AUTO scores for four groups displayed comparable median values. Due to the difference between TRIM and LESION events, this technology shows potential for the early detection of hoof lesions.

Assessing different cross-validation schemes for predicting novel traits using sensor data: An application to dry matter intake and residual feed intake using milk spectral data.

Feed efficiency is important for economic profitability of dairy farms; however, recording daily DMI is expensive. Our objective was to investigate the potential use of milk mid-infrared (MIR) spectral data to predict proxy phenotypes for DMI based on different cross-validation schemes. We were specifically interested in comparisons between a model that included only MIR data (model M1); a model that incorporated different energy sink predictors, such as body weight, body weight change, and milk energy (model M2); and an extended model that incorporated both energy sinks and MIR data (model M3). Models M2 and M3 also included various cow-level variables (stage of lactation, age at calving, parity) such that any improvement in model performance from M2 to M3, whether through a smaller root mean squared error (RMSE) or a greater squared predictive correlation (R2), could indicate a potential benefit of MIR to predict residual feed intake. The data used in our study originated from a multi-institutional project on the genetics of feed efficiency in US Holsteins. Analyses were conducted on 2 different trait definitions based on different period lengths: averaged across weeks versus averaged across 28 d. Specifically, there were 19,942 weekly records on 1,812 cows across 46 experiments or cohorts and 3,724 28-d records on 1,700 cows across 43 different cohorts. The cross-validation analyses involved 3 different k-fold schemes. First, a 10-fold cow-independent cross-validation was conducted whereby all records from any one cow were kept together in either training or test sets. Similarly, a 10-fold experiment-independent cross-validation kept entire experiments together, whereas a 4-fold herd-independent cross-validation kept entire herds together in either training or test sets. Based on cow-independent cross-validation for both weekly and 28-d DMI, adding MIR predictors to energy sinks (model M3 vs. M2) significantly (P < 10-10) reduced average RMSE to 1.59 kg and increased average R2 to 0.89. However, adding MIR to energy sinks (M3) to predict DMI either within an experiment-independent or herd-independent cross-validation scheme seemed to demonstrate no merit (P > 0.05) compared with an energy sink model (M2) for either R2 or RMSE (respectively, 0.68 and 2.55 kg for M2 in herd-independent scheme). We further noted that with broader cross-validation schemes (i.e., from cow-independent to experiment-independent to herd-independent schemes), the mean and slope bias increased. Given that proxy DMI phenotypes for cows would need to be almost entirely generated in herds having no DMI or training data of their own, herd-independent cross-validation assessments of predictive performance should be emphasized. Hence, more research on predictive algorithms suitable for broader cross-validation schemes and a more earnest effort on calibration of spectrophotometers against each other should be considered.

Imputation of missing milk Fourier transform mid-infrared spectra using existing milk spectral databases: A strategy to improve the reliability of breeding values and predictive models.

The use of milk Fourier transform mid-infrared (FT-MIR) spectrometry to develop management and breeding tools for dairy farmers and industry is growing and supported by the availability of numerous new predicted phenotypes to assess the nutritional quality of milk and its technological properties, but also the animal health and welfare status and its environmental fingerprint. For genetic evaluations, having a long-term and representative spectral dairy herd improvement (DHI) database improves the reliabilities of estimated breeding values (EBV) from these phenotypes. Unfortunately, most of the time, the raw spectral data used to generate these estimations are not stored. Moreover, many reference measurements of those phenotypes, needed during the FT-MIR calibration step, are available from past research activities but lack spectra records. So, it is impossible to use them to improve the FT-MIR models. Consequently, there is a strong interest in imputing those missing spectra. The innovative objective of this study was to use the existing large spectral DHI database to estimate missing spectra by selecting probable spectra using, as the match criteria, common dairy traits recorded for a long time by DHI organizations. We tested 4 match criteria combinations. Combination 1 required to have equal fat and protein contents between the sample for which a spectrum was to be estimated and the reference samples in the DHI database. Combination 2 also required an equal urea content. Combination 3 requested equal fat, protein, and lactose contents. Finally, combination 4 included all criteria. When more than one spectrum was found during the search, their average was the estimated spectrum for the query sample. Concretely, this study estimated missing spectra for 1,700 samples using 2,000,000 spectral DHI records. For assessing the effect of this spectral estimation on the prediction quality, FT-MIR equations were used to predict 11 phenotypes, selected as their quantification used different FT-MIR regions. They were related to the milk fat and mineral composition, lactoferrin content, quantity of eructed methane, body weight (BW), and dry matter intake. The accuracy between predictions obtained from actual and estimated spectra was evaluated by calculating the mean absolute error (MAE). The criteria in the fourth and second combinations were too strict to estimate a spectrum for most samples. Indeed, for many samples, no spectra with the same values for those matching criteria was found. The third match criteria combination had a poorer prediction performance for all studied traits and spectral absorptions than the first combination due to fewer matched samples available to compute the missing spectrum. By allowing a range for matching lactose content (±0.1 g/dL milk), we showed that this new combination increased the number of selected samples to compute missing spectra and predict better the infrared absorption at different wavenumbers, especially those related to the lactose quantification. The prediction performance was further improved by performing queries on the entire Walloon DHI spectral database (6,625,570 spectra), and it varied among the studied phenotypes. Without considering the traits used for the matching, the best predictions were obtained for the content of saturated fatty acids (MAE = 0.15 g/dL milk) and BW (MAE = 12.80 kg). Yet, the predictions for the unsaturated fatty acids were less accurate (MAE = 0.13 and 0.018 g/dL milk for monounsaturated and polyunsaturated fatty acids), likely because of the poorer predictions of spectral regions related to long-chain fatty acids. Similarly, poorer predictions were observed for the amount of methane eructed by dairy cows (MAE = 47.02 g/d), likely because it is not directly related to fat content or composition. Prediction accuracies for the remaining traits were also low. In conclusion, we observed that increasing the number of relevant matching criteria helps improve the quality of FT-MIR predicted phenotypes and the number of spectra used during the search. So, it would be of great interest to test in the future the suitability of the developed methodology with large-scale international spectral databases to improve the reliability of EBV from these FT-MIR-based phenotypes and the robustness of FT-MIR predictive models.

Multiple-trait random regression modeling of feed efficiency in US Holsteins.

Residual feed intake (RFI) and feed saved (FS) are important feed efficiency traits that have been increasingly considered in genetic improvement programs. Future sustainability of these genetic evaluations will depend upon greater flexibility to accommodate sparsely recorded dry matter intake (DMI) records on many more cows, especially from commercial environments. Recent multiple-trait random regression (MTRR) modeling developments have facilitated days in milk (DIM)-specific inferences on RFI and FS, particularly in modeling the effect of change in metabolic body weight (MBW). The MTRR analyses, using daily data on the core traits of DMI, MBW, and milk energy (MilkE), were conducted separately for 2,532 primiparous and 2,379 multiparous US Holstein cows from 50 to 200 DIM. Estimated MTRR variance components were used to derive genetic RFI and FS and DIM-specific genetic partial regressions of DMI on MBW, MilkE, and change in MBW. Estimated daily heritabilities of RFI and FS varied across lactation for both primiparous (0.05-0.07 and 0.11-0.17, respectively) and multiparous (0.03-0.13 and 0.10-0.17, respectively) cows. Genetic correlations of RFI across DIM varied (>0.05) widely compared with FS (>0.54) within either parity class. Heritability estimates based on average lactation-wise measures were substantially larger than daily heritabilities, ranging from 0.17 to 0.25 for RFI and from 0.35 to 0.41 for FS. The partial genetic regression coefficients of DMI on MBW (0.11 to 0.16 kg/kg0.75 for primiparous and 0.12 to 0.14 kg/kg0.75 for multiparous cows) and of DMI on MilkE (0.45 to 0.68 kg/Mcal for primiparous and 0.36 to 0.61 kg/Mcal for multiparous cows) also varied across lactation. In spite of the computational challenges encountered with MTRR, the model potentially facilitates an efficient strategy for harnessing more data involving a wide variety of data recording scenarios for genetic evaluations on feed efficiency.

Widespread aneuploidy revealed by DNA microarray expression profiling.

Expression profiling using DNA microarrays holds great promise for a variety of research applications, including the systematic characterization of genes discovered by sequencing projects. To demonstrate the general usefulness of this approach, we recently obtained expression profiles for nearly 300 Saccharomyces cerevisiae deletion mutants. Approximately 8% of the mutants profiled exhibited chromosome-wide expression biases, leading to spurious correlations among profiles. Competitive hybridization of genomic DNA from the mutant strains and their isogenic parental wild-type strains showed they were aneuploid for whole chromosomes or chromosomal segments. Expression profile data published by several other laboratories also suggest the use of aneuploid strains. In five separate cases, the extra chromosome harboured a close homologue of the deleted gene; in two cases, a clear growth advantage for cells acquiring the extra chromosome was demonstrated. Our results have implications for interpreting whole-genome expression data, particularly from cells known to suffer genomic instability, such as malignant or immortalized cells.

Drug target validation and identification of secondary drug target effects using DNA microarrays.

We describe here a method for drug target validation and identification of secondary drug target effects based on genome-wide gene expression patterns. The method is demonstrated by several experiments, including treatment of yeast mutant strains defective in calcineurin, immunophilins or other genes with the immunosuppressants cyclosporin A or FK506. Presence or absence of the characteristic drug 'signature' pattern of altered gene expression in drug-treated cells with a mutation in the gene encoding a putative target established whether that target was required to generate the drug signature. Drug dependent effects were seen in 'targetless' cells, showing that FK506 affects additional pathways independent of calcineurin and the immunophilins. The described method permits the direct confirmation of drug targets and recognition of drug-dependent changes in gene expression that are modulated through pathways distinct from the drug's intended target. Such a method may prove useful in improving the efficiency of drug development programs.

Expression profiling using microarrays fabricated by an ink-jet oligonucleotide synthesizer.

We describe a flexible system for gene expression profiling using arrays of tens of thousands of oligonucleotides synthesized in situ by an ink-jet printing method employing standard phosphoramidite chemistry. We have characterized the dependence of hybridization specificity and sensitivity on parameters including oligonucleotide length, hybridization stringency, sequence identity, sample abundance, and sample preparation method. We find that 60-mer oligonucleotides reliably detect transcript ratios at one copy per cell in complex biological samples, and that ink-jet arrays are compatible with several different sample amplification and labeling techniques. Furthermore, results using only a single carefully selected oligonucleotide per gene correlate closely with those obtained using complementary DNA (cDNA) arrays. Most of the genes for which measurements differ are members of gene families that can only be distinguished by oligonucleotides. Because different oligonucleotide sequences can be specified for each array, we anticipate that ink-jet oligonucleotide array technology will be useful in a wide variety of DNA microarray applications.

Responses of the estrous cycle in dairy cows exposed to electric and magnetic fields (60 Hz) during 8-h photoperiods.

To study the effects of exposure to extremely low frequency (ELF) electric and magnetic fields (EMF) on the estrous cycle of dairy cows under short-day photoperiod, 16 non-lactating, non-pregnant Holstein cows were exposed to a vertical electric field of 10 kV/m and a horizontal magnetic field of 30 microT for 16 h per day in a cross-over design consisting of two sequences. Each sequence included three periods, and each period corresponded to the duration of one estrous cycle. All animals were maintained under short photoperiod (8 h light/16 h dark) during the trial. Exposure to EMF had an impact on the duration of a complete estrous cycle (P<0.01) and on the duration of the luteal phase (P<0.01). The mean duration of one cycle was 19.5+/-0.4 for the control and 21.3+/-0.4 days for the exposed animals, respectively. The mean duration of the luteal phase was 15.4+/-0.4 days for the control and 17.2+/-0.4 days for the exposed group. The total area under the progesterone (P(4)) curve, the amplitude of the curve or the slope of the P(4) rise at the onset of the luteal phase were not affected by EMF exposure. Results indicate that exposure to EMF may increase the duration of the estrous cycle.

An analysis of timeout and response cost in a programmed environment.

A group of mildly retarded adolescents with high rates of antisocial behavior was exposed to two parameters of timeout and response cost within the context of a programmed environment. For five of the six subjects, the two higher values (30 tokens response cost or 30 min timeout) were significantly more suppressive than the lower values (five tokens or 5 min). For the one remaining subject, there was a strong relationship in the opposite direction. Also, the timeout and response cost of higher value became increasingly more suppressive over time, whereas those of lower value did not. There were few appreciable differences between the timeout and response cost of similar magnitude. A discussion of these results is presented in support of the notion that the functional aversiveness of timeouts (and response costs) appears to be critically dependent upon interactions with the environmental conditions in which they are implemented and the reinforcement histories of the subjects.

Social policy and the role of the behavior analyst in the prevention of delinquent behavior.

The purpose of this article is to encourage behavior analysts to expand their domain of interest and application to include the "social/political" contingencies that are developed and implemented by policymakers and lawmakers. Using the Vermont juvenile justice system as a prototype, examples are provided that focus on the tertiary, secondary, and primary prevention of delinquent behavior.

Exposure of pregnant dairy heifer to magnetic fields at 60 Hz and 30 microT.

Thirty-two pregnant Holstein heifers weighing 499 +/- 45 kg, at 3.1 +/- .7 months of gestation and 21 +/- 2.0 months of age were confined and exposed to 30 microT magnetic fields (MFs) and a 12 h light/12 h dark light cycle. The heifers were divided into two replicates of 16 animals. Each replicate was divided into two groups of eight animals each, one group the non-exposed and the second, the exposed group. The animals were subjected to the different treatments for 4 weeks. After 4 weeks, the animals switched treatment, the exposed group becoming the non-exposed group and vice versa. Then the treatment continued for 4 more weeks. Catheters were inserted into the jugular vein, and blood samples were collected twice a week to estimate the concentration of progesterone (P4), melatonin (MLT), prolactin (PRL), and insulin-like growth factor 1 (IGF-1). Feed consumption was measured daily. The results indicated that exposure of pregnant heifers to MF similar to those encountered underneath a 735 kV high tension electrical power line for 20 h/day during a period of 4 weeks produces slight effects. This is evidenced by statistically significant higher body weight (1.2%), higher weekly body weight gain (30%), and decreases in the concentration of PRL (15%) and IGF-1 (4%) in blood serum. The absence of abnormal clinical signs and the absolute magnitude of the significant changes detected during MF exposure, make it plausible to preclude any major animal health hazard.

The importance of the schizo-affective psychoses within the psychopathological and nosological systematics.

Schizo-affective psychoses lead more often to reintegration of the paranoid-hallucinatory pattern than schizophrenic psychoses. The author interprets schizo-affective psychoses in the light of his systematic psychopathology and concludes that excitation is intensified in comparison with cyclothymia. Ego destruction is more serious, but paranoid manifestations decrease in the course and emotional syndromes become more pronounced. Prognosis depends on the intensity of therapeutic efforts in the sense of psychopharmacological and supportive therapies and is not prestabilized.

[The role of neurasthenic syndrome in depression (author's transl)]. / Die Bedeutung der Erschöpfung bei Depressionen

In endogenous depression a neurasthenic syndrome is partially included. In 100 male cases whose diagnoses merely stated "endogenous depression" without further remarks like "neurotic traits" or "reactive influences", we found in 48 cases a clear neurasthenic syndrome. It is suggested that these symptoms often lead to the diagnosis of endogenous depression. Pharmacotherapy is partially directed to the neurasthenic condition. Hereditary factors may play a part in the unability of the later endogenous depressive to relax.

The role of individualized care in a service delivery system for children and adolescents with severely maladjusted behavior.

Individualized care is a total system of care that is tailored to a child with severely maladjusted behavior. The services are unconditional, flexible, child and family focused, and interagency coordinated. The services follow the child until the child is adjusting in a normalized, mainstream environment. Individualized care is illustrated through two different projects. One is the Alaska Youth Initiative where individualized care was used to return children from out-of-state, residential programs. The other is Project Wraparound where it was used to prevent children from being removed from their families. This paper begins with the principles of individualized care and then describes the ecological, multilevel assessment process that coincides with the delivery of services. A case example from Project Wraparound is provided for clarification. Following the case example is a discussion of the need for evaluation data with some suggested strategies for documenting effectiveness. The final section focuses on two barriers to the implementation of individualized care. One is the tendency to think in terms of component programs rather than individualized services. The other barrier is the competition for scarce resources. Strategies are presented for overcoming both barriers.

Production of prostaglandin by late-gestation porcine placental cells in vitro.

Fifteen sows were assigned to three groups of five each, according to gestational age (109 days, 114 days or labour). Two fetuses per sow were chosen at random, and amnion, allantochorion, amniochorion, amniotic fluid and fetal urine were collected. Tissues were enzymatically dispersed and incubated for 1, 2, 3 or 4 h and the prostaglandin (PG) content of the supernatant medium was measured by radioimmunoassay. In general, all placental cell types produced at least three times more prostaglandin E (PGE) and 6-keto-PGF1 alpha than PGF. Production did not vary across gestational age, except that production of 6-keto-PGF1 alpha was lower in cells collected during labour, resulting in a relative increase in PGF and PGE. Aminochorion cells had a lower de novo capacity to synthesize PG than did allantochorion or amniochorion, whereas treatment of allantochorion with preterm amniotic fluid, preterm or term fetal urine resulted in increased PG output. These results demonstrate that porcine placental cells can synthesize and metabolize prostaglandin in late gestation but suggest that their capacity to produce PGI2 (as measured by 6-keto-PGF1 alpha) is lower than for other prostaglandins during labour.

Effects of electric and magnetic fields on nocturnal melatonin concentrations in dairy cows.

Sixteen multiparous, pregnant, lactating Holstein cows (weighing 600 +/- 50 kg, at 184.8 +/- 52 d of lactation, and at 101.9 +/- 43 d of gestation) were confined to wooden metabolism cages and exposed to a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 microT. The trial was conducted using a switchback statistical design. Cows were divided into two sequence groups of 8 cows each. One sequence group was exposed for three periods of 28 d each. The electric and magnetic fields were off during the first period, on during the second period, and off during the final period. The second sequence group was exposed for three periods also, but the activity of the fields was reversed (on during the first period, off during the second period, and on during the third period). On d 25 of each exposure period, blood samples were obtained every 0.5 h for 14 h starting at 1700 h to determine melatonin concentration. Nocturnal melatonin concentrations did not show any variation that could be attributed to exposure to electric and magnetic fields.

Progesterone concentrations during estrous cycle of dairy cows exposed to electric and magnetic fields.

Sixteen multiparous nonpregnant lactating Holstein cows (each weighing 662 +/- 65 kg in 150.4 +/- 40 day of lactation) were confined to wooden metabolic cages with 12:12 h light:dark cycle during the experiment. The cows were divided into two sequences of eight cows each and exposed to electric and magnetic fields (EMF) in an exposure chamber. This chamber produced a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 microT at 60 Hz. One sequence was exposed for three estrous cycles of 24 to 27 days. During the first estrous cycle, the electric and magnetic fields were off; during the second estrous cycle, they were on; and during the third estrous cycle, they were off. The second sequence was also exposed for three 24 to 26 days estrous cycles, but the exposure to the fields was reversed (first estrous cycle, on; second estrous cycle, off; third estrous cycle, on). The length of each exposure period (21 to 27 days) varied according to the estrous cycle length. No differences were detected in plasma progesterone concentrations and area under the progesterone curve during estrous cycles between EMF nonexposed and exposed periods (2.28 +/- 0.17 and 2.25 +/- 0.17; and 24.5 +/- 1.9 vs. 26.4 +/- 1.9 ng/ml, respectively). However, estrous cycle length, determined by the presence of a functional corpus luteum detected by concentrations of progesterone equal to or more than 1 ng/ml plasma, was shorter in nonexposed cows than when they were exposed to EMF (22.0 +/- 0.9 vs. 25.3 +/- 1.4 days).

Effect of 10 kV, 30 microT, 60 Hz electric and magnetic fields on milk production and feed intake in nonpregnant dairy cattle.

Milk production is the main agricultural income in the province of Québec, and the electrical distribution network traverses the rural dairy production region. This study evaluates the hypothesis that electric and magnetic fields may affect dairy production. Sixteen multiparous nonpregnant lactating Holstein cows (weighing 662 +/- 65 kg and with 150.4 +/- 40 days of lactation) were confined to wooden metabolic crates during the experiment with a 12:12 h light:dark cycle. The cows were divided into two replicates of eight cows each and exposed to a vertical EF of 10 kV/m and an uniform horizontal MF of 30 microT at 60 Hz. Replicate one was exposed for three periods. Each period was represented by an estrous cycle ranging from 24 to 27 days. During the first period, the electric and magnetic fields (E&MF) were off; during the second period they were on; and during the final period, they were off. The second replicate was exposed for three periods also, but the exposure protocol was reversed (first period, on; second period, off; last period, on). Exposure to E&MF (on) resulted in an average decrease of 4.97, 13.78, and 16.39% in milk yield, fat corrected milk yield, and milk fat, respectively; and an increase of 4.75% in dry matter intake.

Differential diagnosis importance of the creatine kinase isoenzyme pattern in delirium tremens.

Total CK and CK-MB (by the inhibition test, Merck-1-CK-MB) were measured in 33 patients which had to be admitted to the department of psychiatry due to acute withdrawal symptoms (predelirium, delirium) caused by chronic alcohol abuse. The results were evaluated together with the routinely performed laboratory determinations as well as clinical examination and morphologic investigations (ECG, X-ray examination of the thorax, EEG, CT). The results show that the CK-MB/total CK relationship represents also in these patients the most reliable parameter to discriminate elevated total CK values. In no but one case a substantial CK-BB release from the central nervous system could be demonstrated by the inhibition test. In 83% of the patients with elevated total CK activities it was possible to exclude an affection of the heart muscle (CK-MB portion below 6%). The CK-MB/total CK-quotient was clearly superior to the total CK/GOT relationship, by which a myocardial affection could be excluded in less than 40%. In four patients the CK-MB portion was above the critical decision limit of 6%: three obtained between 6% and 7%, one even 17%. The results suggest that the CK-MB/total CK-quotient may represent the most sensitive and reliable parameter of myocardial affection in patients with an alcohol intoxication and/or a delirium tremens.

Macro- and trace element concentrations in blood plasma and cerebrospinal fluid of dairy cows exposed to electric and magnetic fields.

Eight multiparous, nonlactating pregnant Holstein cows (at 198 +/- 35 days of gestation and weighing 608 + 24 kg) and seven nonlactating nonpregnant ovariectomized heifers (weighing 370 + 29 kg) were confined to wooden metabolism crates in an electric and magnetic field chamber. Subarachnoidal catheters were inserted before the activation of the electric and magnetic fields. For 30 days, cows and heifers were continuously exposed in separate trials to electric and magnetic fields (60 Hz, 10 kV/m, and 30 microT). Blood plasma and cerebrospinal fluid samples were collected for 3 consecutive days before the exposure period, the last 3 days of the exposure period, and for 3 days starting 5 days after the exposure period. Concentrations of Ca, Mg, Cu, Zn, Fe, Mn, Na, P, and K in blood plasma and cerebrospinal fluid were determined. Exposure to electric and magnetic fields resulted in decreased concentrations of Mg in blood plasma and in increased concentrations of Ca and P and decreased concentrations of Fe and Mn in cerebrospinal fluid.