Bayofly Pour-on: evaluation of mastitis prophylaxis in grazing cattle in southern Germany.

The efficacy of Bayofly Pour-on (cyfluthrin) in preventing summer mastitis (caused by Actinomyces pyogenes) was assessed in grazing cattle from several regions of southern Germany (Allgau, Oberschwaben, Schwabische Alb and Black Forest) during June-September 1986. A total of 744 cattle from 16 farms were used in the trial (including an untreated control herd of 48 animals). Animals were treated on the dorsal line between the shoulder blades with 10 ml Bayofly; 5 herds were given a 2nd dose 4-8 weeks after the first treatment. Data on the treatment, behaviour, fly infestation and incidence of mastitis in animals is tabulated. Depending on the weather, a fly-repellent effect of up to 4 weeks was observed (against "headflies", Haematobia irritans, H. stimulans [Haematobosca stimulans] and gadflies [Tabanidae]); this was reduced in periods of prolonged or heavy rainfall. It is suggested that effective control of summer mastitis can be achieved with an effective, long-term fly control scheme.