Cow sensitivity to electricity during milking

Possible causes of aberrations in adverse grouping behavior of dairy cows: A field study

In the Dutch national surveillance system, an increasing number of reports were received in the summer of 2017 from farmers about unusual behavior of their cows. The cows were grouping during the day in summer in one part of the barn and did not move for several hours, which, according to the farmers, led to reduced food and water intake and lying time and resulted in decreased milk production and increased risk of lameness. Many farmers perceived magnetic fields from, for instance, high-voltage lines, automated milking systems, or solar panels as possible causes for the behavior of their cows. Our aim for the study was to study potential factors such as magnetic fields and other factors such as barn climate and insect burden for adverse grouping behavior of dairy cows in the barn. For each case herd, 2 control herds were selected in the same postal area code. A case was a herd in which cattle grouped at least on 7 occasions in a month for several hours. In a control herd, the cows were in the barn during the same time period as in the matching case herd but did not show adverse grouping behavior. A questionnaire was administered by telephone in 31 case herds and 62 control herds. The questionnaire gathered information on behavior of the cows and potential risk factors. In addition, data on the distance of the herd to high-voltage lines was obtained. From a total of 74 variables, all variables with a P-value ≤0.10 were included in full multivariable logistic regression model. Backward selection was carried out at P ≤ 0.10. The grouping behavior of the cows started in most herds in June, was seen only during the day, and lasted mostly 6 to 8 h, with cows often grouped in the northern part of the barn. Identified risk factors appeared to be recently constructed barns, measured stray voltage in barns, and presence of fans in barns. Given the cross-sectional design of the case-control study, causality for these risk factors leading to adverse behavior of the cows could not be proven. Dissemination of the results to farmers hopefully results in measures that can prevent the unusual grouping behavior of cows.

Relationship of electric power quality to milk production of dairy herds - field study with literature review

Public Utility Commissions (PUC) in several states adopted 0.5 volt rms (root mean squared) or 1.0 milliampere as the actionable limit for utilities to respond to complaints of uncontrolled voltage. This study clearly shows that the actionable level should be reduced to 10 mV p-p (peak-to-peak), which is 140 times less than the current standard. Dairy farmer complaints that animal behavior and milk production were affected by electrical shocks below adopted standards were investigated on 12 farms in Wisconsin, Michigan, and Minnesota. Milk production per cow was determined from daily tank-weight pickup and number of cows milked. Number of transient events, transients, voltage p-p, waveform phase angle degree, sags, and sag-Vrms were measured from event recorders plugged into milk house wall outlets. Data from 1705 cows and 939 data points were analyzed by multiherd least-squares multiple regression and SAS-ANOVA statistical programs. In five herds for 517 days, milk/cow/day decreased -0.0281 kg/transient event as transient events increased from 0 to 122/day (P<0.02). Negative effects on milk/cow/day from event recorder measurements were significant for eight independent electrical variables. Step-potential voltage and frequency of earth currents were measured by oscilloscope from metal plates grouted into the floor of milking stalls. Milk decreased as number of 3rd, 5th, 7th, 21st, 28th, and 42nd harmonics and the sum of triplen harmonics (3rd, 9th, 15th, 21st, 27th, 33rd, and 39th) increased/day (P<0.003). Event recorder transient events were positively correlated with oscilloscope average V p-p event readings. Steps/min counted from videotapes of a dancing cow with no contact to metal in the barnyard were correlated with non-sinusoidal 8.1 to 14.6 mV p-p impulses recorded by oscilloscope for 5 min from EKG patches on legs. PUC standards and use of 500-Ohm resistors in test circuits underestimate effects of non-sinusoidal, higher frequency voltage/current common on rural power lines.

Quantitative assessment of physiological and behavioural parameters in healthy dairy cows evoked by transcutaneous electrical nerve stimulation of the udder

The pain and distress associated with transcutaneous electrical nerve stimulation (TENS) of the udder was evaluated by treating 20 healthy dairy cows with an electrical udder stimulator. This generated a sequence of pulses (frequency: 160±10% impulses per second, duration 250 μs) and provided voltage ranges from 0 to 10 volts (±10%). Trials took place on three consecutive days, twice daily after morning and evening milking. Daily sessions were divided into two periods: (1) control (sham treatment) and (2) treatment (real treatment). Physiological (heart rate, respiratory rate, and plasma cortisol concentration) as well as ethological parameters (kicking, weight shifting, and looking backwards to udder) were defined as pain-indicating parameters and observed. Evaluation of data showed that only one parameter (kicking) was significantly increased during real treatment compared to sham treatment. It is concluded that the TENS therapy tested in this study can evoke changes in behaviour (increased kicking) consistent with an experience of pain in some cows.

Medium-term effects of repeated exposure to stray voltage on activity, stress physiology, and milk production and composition in dairy cows

The medium-term effects of permanent or random exposure to stray voltage applied to the water trough were evaluated on milk production and stress physiology in lactating dairy cows. Seventy-four Holstein cows were assigned during two 8-wk experimental periods to 1 of 3 treatments. The treatments were permanent exposure to voltage (PERM, 1.8 V, n=23) applied to the water trough, random exposure to voltage (RAND, 1.8 V, 36 h/wk, n=25), and no exposure to voltage (control, n=26). On the first day of voltage exposure, PERM cows had higher activity levels than control cows (9.8+/-2.70 vs. -2.3+/-2.74 14-s periods of movement/h). During the eighth week of exposure, RAND cows had higher activity levels than control cows (4.2+/-3.64 vs. -7.7+/-3.54 14-s periods of movement/h) and higher milk cortisol concentration than PERM cows (0.21+/-0.024 vs. 0.14+/-0.020 ng/mL). No differences were observed between treatments for cortisol response after an ACTH challenge during the seventh week of exposure. No effects of voltage exposure were observed on production traits and daily water intake. There was a transient decrease in milk yield on the second day of exposure in PERM cows (-1.4+/-0.74 kg) and on the third day of exposure in RAND cows (-3.5+/-1.03 kg) compared with control cows. In dairy cows, permanent or random exposure to stray voltage (1.8 V; 3.6 mA) could induce a transient stress response. Moreover, unpredictable voltage exposure could be considered a mild stressor, with slight modifications in stress physiology and activity but no impairment in production in the medium term.

Oxytocin release and milk removal in ruminants

Before milking, less than 20% of the milk yielded by dairy cows is stored within the cistern, where it is immediately available for removal. Most of the milk is available for the milking machine only after milk ejection, which occurs in response to tactile teat stimulation and oxytocin release. For complete milk removal, milk ejection is necessary throughout the entire milking process. The continuation of stimulatory effect of the milking machine until the end of milking is, therefore, essential. Premilking teat stimulation causes induction of alveolar milk ejection before the start of milking. Thus, bimodal milk flow curves (i.e., interruption of milk flow after removal of the cisternal milk) are avoided. Continual ejection of milk is dependent on the presence of elevated oxytocin concentrations during the entire milking. Any interruption of the milk ejection process can disturb milk removal. Disruption of milk removal can be caused by peripheral inhibition of oxytocin effects on the mammary gland or by inhibition of oxytocin release by the central nervous system. Peripheral inhibition is induced by elevated concentrations of catecholamines through stimulation of alpha-adrenergic receptors in the mammary gland, likely via changes in ductal resistance. Inhibition of oxytocin release by the central nervous system has been observed in primiparous cows immediately after parturition, during peak estrus, and during milking in unfamiliar surroundings; concentrations of beta-endorphin and cortisol are elevated in this situation. However, the role of endogenous opioid peptides in the inhibition of oxytocin release in cows remains unclear. In conclusion, during machine-milking, the physiological requirements of the cows need to be considered, and, most importantly, stressors must be minimized.