Unipolar Square Research Articles

Effect of electrical stunning frequency on ventricular fibrillation, downgrading and broken bones in broilers, hens and quails

The effect of stunning current frequency on the incidence of ventricular fibrillation was determined in broilers and hens. When a pulsed unipolar square wave (DC) was used the incidence of ventricular fibrillation decreased as the frequency was increased beyond 125 Hz. When a sinusoidal AC was used, 50 Hz killed some of the birds whereas at the corresponding r.m.s. currents no birds experienced a ventricular fibrillation with 1500 Hz. In quail, it was found that between 45 and 110 mA (50 Hz) all birds experienced a ventricular fibrillation. The effect of 50, 200 and 350 Hz square wave DC on carcass downgrading was examined in broilers, and there were no differences between the groups. It was concluded that there were few advantages from using high frequency stunning currents in poultry.

Exposure of Chicken Embryos to Selected Magnetic Fields

Tests were made to determine whether the development of chicken embryos was altered by exposure to time-varying magnetic fields. Unipolar square waves with periods of 100μs, 1, 10, 20, and 30ms, and 20ms bipolar square and sinusoidal waves were tested. The nominal peak strength for each experiment was 1μT. Neither the morphogenesis of the embryo nor the temporal aspects of development was altered by any tested field. Fertile eggs of several different strains of chickens were also tested to determine whether strain sensitivity to certain magnetic fields can account for the reports of positive effects of magnetic fields upon development. No significant alterations were noted in the embryos of any of the tested strains. Published reports of alterations in development following exposure to similar low level magnetic fields have not been confirmed in this laboratory.

Effects of electrical currents on wound contraction.

A prospective randomized evaluation of the potential beneficial effects of electrical currents has been studied in 13 wounds in 7 pigs. The effect of electrical current was assessed by evaluation of wound contraction and residual open wound area. A 35 mA unipolar square wave stimulation for one-half hour stimulation periods twice a day showed consistent results in 13 wounds in 7 pigs. Application of negative currents shows no stimulation of wound contracture. In fact, negative currents seemed to retard wound contracture. After two weeks of treatment, the control wound had decreased to 58% of its original size, whereas wounds treated with negative currents were 93% of their original size. On the other hand, negative currents alternating with positive currents increased the rate of wound contraction for the first two to three weeks of treatment. At two weeks these wounds were 18% of their original size and continued to decrease to 5% by three weeks. Wound contraction may be increased by electrical currents. The concept of alternating negative and positive currents has not been previously described and seems to offer some promise in this early study. Further work is underway to define the exact values required for the maximum effects on wound contraction.

Effects of 100-Hz magnetic fields with various waveforms on the development of chick embryos.

Chick embryos were exposed during their 52 first hours of development to 100-Hz magnetic fields. Sinusoidal, square and pulsed waveforms were used at average field strengths from 0.1 A/m to 80 A/m. After exposure, the embryos were examined for abnormalities and classified by the developmental stages. When bipolar oscillations (oscillating at both sides of the zero-level) were used, the percentage of abnormal embryos was significantly increased above 1 A/m. In exposure to unipolar square waves, no significant effect on the percentage of abnormalities could be demonstrated. The developmental stage was possibly affected by unipolar square waves at 0.1 A/m, all other field strengths and waveforms being apparently ineffective.