Dairy Herd Improvement Holstein herd summary records (n = 11,259) were obtained for the year ending 1998. Reasons cows reportedly left the herd based on termination codes were analyzed for the effect of region, herd size, and herd milk production level. Regions were: North, Midsouth, and South. Herd sizes were: small (25 to 99), low medium (100 to 149), high medium (150 to 299), and large (greater than or equal to 300 cows). Milk production levels were: low (less than 7258 kg), medium (7258 to 9072 kg), and high (greater than 9072 kg). The overall percentage of cows leaving the herd was higher in the Midsouth than the South and increased with herd size. Low producing herds reported a lower percentage of cows left than high producing herds. Herds in the South reported more cows leaving for reproduction, death, and low production and fewer leaving for mastitis. Herds in the North and Midsouth reported more cows leaving for injury/other and disease, respectively. Cows left herds for disease less frequently in the North. Large herds in the South had a higher percentage leaving for low production than any herd size group in the North. Small herds reported more cows leaving for reproduction and mastitis than high medium and low medium size herds. The percentage of cows leaving for feet and leg problems was lowest for small size herds. High producing herds reported more cows leaving for reproduction, mastitis, feet and legs and disease.

Increasing production by increasing milking frequency (MF) is a management option available to dairy producers. This study examined effects of MF and interactions with region and herd size on measures of herd performance. Dairy Herd Improvement (DHI) Holstein herd summary records (n = 10,754, 10,550, and 10,438) for the years 1998, 1999, and 2000 were classified by MF: two times a day (2X) milking vs three times a day (3X); herd size: small (< 250 cows) and large (> or = 250 cows); and region: North and South. Percentage of herds milking 3X by year were 7.0, 6.7, and 7.1. Rolling herd average milk production was 16, 16, and 15% higher for herds milking 3X than herds milking 2X for the respective years. Herds milking 3X in the North region outproduced herds milking 3X in the South region. Milk fat and protein percentages were lower for herds milking 3X during all 3 yr. Differences in energy-corrected milk production between herds milking 3X and herds milking 2X were 14.5, 13.4, and 13.4% during the respective 3 yr as a result of lower component percentages for herds milking 3X. Herds milking 3X had more days open and higher actual calving intervals than herds milking 2X. Services per pregnancy for herds breeding primarily by artificial insemination were higher for herds milking 3X than for herds milking 2X. Somatic cell scores and weighted somatic cell counts were lower for herds milking 3X than herds milking 2X. Herds milking 3X had a higher percentage of somatic cell scores in the low range (0 to 3) and a lower percentage in the high range (7 to 9). Mean percentages of cows entering and leaving the herd were higher for herds milking 3X during all 3 yr.

Three milking frequency treatments were compared: twice daily milking; thrice daily milking until milk dropped below 24 kg; thrice daily milking until milk dropped below 31 kg. Three time milking was at least 45 days but no more than 150 days. Cows (12 to 14 per group) were managed alike except for milking frequency. In early lactation, increased milking had little effect. With time the superiority in yields increased such that cows on three times for 150 days were outproducing two time cows by 20%. Cumulative milk yields were greater for the thrice groups than for the twice group by 5% at 56 days, 11 and 8% at 154 days, 11 and 9% at 182 days, and 10% at 280 days. Fat percentage, adjusted for previous lactation fat percentage, averaged .2 to .3% lower for the cows milked three times until 24 kig but only .1% lower for cows milked thrice until 31 kg. Increased yield was primarily from prolonged peak yield and less subsequent decline. Switching from three to two milkings decreased yield 6 to 8% in the 1st wk. However, three time milking had a positive carryover, apparently due to higher starting yield at the point at which they were switched.

Differences in selected Dairy Herd Improvement (DHI) performance parameters among regions and herds of different size categories were evaluated. DHI records from herds in 37 states were grouped into North, Midsouth, and South regions, and six herd size categories (20 to 49, 50 to 99, 100 to 149, 150 to 249, 250 to 449, and > or = 450 cows). The North region had higher income over feed costs (IOFC); milk, fat, and protein rolling herd averages; summit milk; standardized 150-d milk; and percentage of cows in milk, than the other regions. These variables were lowest for the South region. Cost/45.4 kg of milk, days open, days dry, and somatic cell counts were lowest in the North region and were highest in the South. Percentage of cows entering and leaving the herd were highest in the Midsouth and were lowest in the South. Larger herds had higher total feed cost, IOFC, milk, fat, and protein rolling herd averages, summit milk, standardized 150-d milk, percentage of cows entering and percentage leaving the herd than smaller herds. Larger herds had lower somatic cell counts than smaller herds. Cost/45.4 kg of milk, days dry, days open, days in milk, and percentage of cows in milk did not show clear trends among different herd sizes. There were significant interactions between region and herd size for some of the variables.

Various commonly used antiseptics were tested against three strains of methicillin-resistant Staphylococcus aureus (MRSA) at stock strength and in serial 10-fold dilutions. The stock solutions of 4% chlorhexidine gluconate-alcohol (Hibiclens), 1% p-chloro-m-xylenol (Acute-Kare), and 3% hexachlorophene (Phisohex) produced 2-log reductions of MRSA after a 15-s exposure, but even after 240 s, these solutions failed to kill all the MRSA. Povidone-iodine (Betadine) solution was maximally effective at the 1:100 dilution, killing all the MRSA within 15 s; other dilutions were less effective, though each killed the MRSA within 120 s. Similar results were obtained with three different strains of methicillin-susceptible S. aureus. Thus, of the four most commonly used antiseptics, povidone-iodine, when diluted 1:100, was the most rapidly bactericidal against both MRSA and methicillin-susceptible S. aureus.