Calves exposed to a bovine respiratory syncytial virus showed mild clinical signs of respiratory illness and responded serologically. The disease occurred in the presence or absence of circulating antibodies, but there was no evidence of exacerbation of the disease due to preexisting serum antibody. Nasal secretory antibody appeared to protect the calves against the disease. Calves previously exposed to the virus were immune to challenge. The virus was recovered at a high frequency when specimens of nasal secretion (not subjected to freezing and thawing) were inoculated into susceptible cells within 1 hr after collection.

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An electrical stunner, designed such that both frequency and voltage could be varied independently, was tested to determine which combination of voltage and frequency resulted in a stun which maximized bleed-out in broilers. Frequencies and peak voltages tested were, respectively, 30, 60, 120, 240, 480, and 960 Hertz (Hz, cycles per sec), and 50, 60, 70, 80, 90, and 100V. The combination which resulted in best blood release was a peak voltage of lOOv, average voltage of 30v, and a frequency of 480 Hz. The variable frequency stunner was compared to an AC stunner (60 Hz, 50v) for maximizing bleed-out in male broilers. No significant difference was found between the two circuits.Two bleed-out time intervals were tested using three electrical circuits: AC, DC, and variable frequency. Approximately twice as much blood was collected during the additional 30 sec time interval when the DC circuit was employed. It is suggested that processing plants using DC stunners increase bleed-out time from the standard 60 sec to at least 90 sec before the broilers enter a scalder.The electrical cost of operating three electrical circuits for stunning poultry was evaluated. The AC circuit (60 Hz) was most efficient and the DC circuit least efficient in terms of electrical energy used to stun a given broiler. The variable frequency stunner ranked second.

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