Regional Production Differences

The DHI records from 37 states were grouped into North, Midsouth, and South regions and six herd sizes (20 to 49, 50 to 99, 100 to 149, 150 to 249, 250 to 449, and >450 cows). Data were analyzed by region and by herd size for the year 1998. The North region had higher income over feed cost, milk, fat, and protein rolling herd averages than other regions. These variables declined for the Midsouth and were lowest for the South. Days open and somatic cell score (SCS) were lowest in the North and highest in the South. Large herds had higher total feed cost, income over feed cost, milk, fat, and protein rolling herd averages than smaller herds. For the period 1990 to 1999, the data were analyzed for the trend in change over time for each of the regions. Milk production per cow, total feed cost, income over feed cost, days open, and herd sizes increased in the period from 1990 to 1999. Somatic cell score decreased. Different rates of increments over the last decade have made differences among regions larger for milk production, total feed cost, income over feed cost, herd size, and SCS. There were no differences in the rate of change for days open. Milk production per cow and total feed cost increased at higher rates in larger herds, making the gap between these and smaller herds larger over time. Income over feed cost, days open, and herd size changes had similar rates of change during the decade, keeping differences among herd sizes constant over time. The SCS decreased at a higher rate in the smallest herds than in larger herds, making the gap between them smaller. (