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In extensive pastoral dairy farming systems herds graze 12 months of the year with the majority fed a near-100% pasture or conserved pasture diet. The viability of automatic milking in these systems will depend partly upon the amount of supplementary feed necessary to encourage cows to walk from the pasture to the milking unit but also on the efficient use of the automatic milking system (AMS). This paper describes a study to determine the importance of offering concentrate in the milking unit and the effect of minimum milking interval on cow movement and milking performance in a pasture-based AMS. The effects of feeding rate (FR0=0 kg or FR1=1 kg crushed barley/d) and minimum milking interval (MM6=6 h or MM12=12 h) on cow movement and behaviour during milking were studied in a multi-factorial cross-over (feeding level only, 4 weeks per treatment) experiment involving 27 mixed-breed cows milked through a single AMS. Feeding 1 kg barley in the milking unit resulted in a higher visiting frequency to the pre-selection unit (FR0=4.6 visits/d, FR1=5.4 visits/d, sed=0.35, P<0.05) and a higher yield (FR0=22.5 kg/d, FR1=23.6 kg/d, sed=0.385, P<0.01) but had no effect on milking frequency (FR0=1.6 milkings/d, FR1=1.7 milkings/d, sed=0.04, NS). Minimum milking interval was the major factor influencing milking frequency (MM6=1.9, MM12=1.4 milkings/d, sed=0.15, P<0.01). The absence of feeding in the milking unit had no negative effect on behaviour during milking or the number of cows that had to be manually driven from the paddock. The results show that automatic milking can be combined with a near-100% pasture diet and that milking interval is an important determinant for maximizing milk harvested per AMS.

We have investigated the responses of cow teats to machine milking in a study of relatively newly installed commercial milking parlours fitted with one of two types of milking cluster. The first was a common type with a large claw volume (> 200 ml), 15-16 mm i.d. long milk tube, 10 mm short pulse tube, cluster weight < 3-2 kg and used alternate pulsation. The second was a more traditional type with a 150 ml claw bowl volume, 13.5 mm i.d. long milk tube, 8 mm short pulse tube, cluster weight approximately 3.5 kg and used simultaneous pulsation. We scored approximately 50 cows in each of 20 herds, all within 60 s of cluster removal, for changes from the premilking teat condition: teat colour (creation of reddening or blueness), firmness, thickening at the base of the teat associated with the position of the liner mouthpiece, and whether the teat duct orifice was open. There were statistically significant differences in the proportion of cows displaying these four alterations in teat condition between herds using the two types of cluster. The more common type of cluster was always associated with better teat condition. The cause and effect of poorer teat condition have not been fully established and are likely to be multifactorial. The principal risk factors may be cluster weight, overmilking, vacuum applied during the overmilking phase and the design of the liner mouthpiece.