Evaluation of an experimental milking pulsation system for effects on milking and udder health.

This study was to test whether cows milked by an experimental pulsation method differed from cows milked with conventional pulsation milking in somatic cell count (SCC), intramammary infections (IMI) defined by milk bacteriological culture results, teat end condition, or milk flow rate. The study design was a 1-yr trial with a completely randomized block crossover. Holstein cows were blocked into 15 pairs of contemporaries. Both cows from each pair were milked with experimental pulsation and with conventional pulsation for 6 mo, in reverse order from each other. The SCC (217,000/ml) of experimentally milked cows was not significantly different from SCC of conventionally milked cows (175,000/ml). Mean milk flow rate was 5.2 lb/min (2.4 kg/min) for experimentally milked cows and 5.3 lb/min (2.4 kg/min) for conventionally milked cows, not significantly different. Differences among the experimentally and conventionally milked cows, respectively, in new (13.5 and 12.7%), chronic (12.9 and 8.9%), and negative (73.6 and 78.4%) quarter culture results were not significant. New IMI per 100 d of lactation were 1.50 and 1.46, and chronic IMI per 100 d were 1.85 and 1.27, for experimentally and conventionally milked cows, respectively. These IMI rates were not significantly different between pulsation types. There were more new Staphylococcus aureus IMI associated with conventional pulsation, but overall cases of Staph. aureus were similar between the two types of pulsation. Teat end scores for the experimentally and conventionally milked cows, respectively, were good (6.5 and 11.7%), intermediate (68.2 and 66.9%), and poor (25.3 and 21.4%), not significantly different. These results support previous studies, which have found that except for complete failure of pulsation, differences in pulsation characteristics apparently have little effect on milking and udder health.

Milk production, water consumption, and somatic cell count responses of cows subject to one to two volts of alternating current.

A dairy farm located in central New York was visited because of complaints of electrical shock in the farmhouse shower and the milk house sink. As much as 2 volts AC of potential difference was measured between the waterline and the cow platform (cow-contact voltage). Voltage was coming from the primary neutral wire. The farm's electrical service was modified so that the farmstead could be connected or disconnected from the primary neutral wire at 2-week intervals for 12 weeks. When connected to the primary neutral wire, voltage between waterline and floor ranged between 0 and 1.8 volts, producing estimated current flow through cows of 3.6 to 4.9 mA; when disconnected from primary neutral wire, voltage between waterline and floor was less than 0.1 volt. There was no difference in mean milk production, bulk tank milk somatic cell count, or water consumption among periods when cows were exposed or unexposed to voltage. Despite statistical nonsignificance, the values for somatic cell count were lower and water consumption was higher when cows were exposed to voltage than when they were not.

Association between neutral-to-earth and cow contact voltage on New York dairy farms.

Cow contact (or "stray") voltage has been associated with various health and management problems in dairy cows. Neutral-to-earth voltage (voltage between the service entrance neutral bus and a reference ground rod) has been equated with cow contact voltage in previous research. To investigate the association between these two voltages, single ("instantaneous") and continuous voltmeter measurements were made at 97 farms in New York. A small positive correlation was found between all single neutral-to-earth and cow contact measurements. Eleven farms with continuous neutral-to-earth readings of .5 V or greater were resurveyed. Eight of the resurveyed farms showed a small or nonexistent correlation between the two voltages. Neutral-to-earth voltage is not recommended as an indicator to predict the presence or magnitude of cow contact voltage.