 AIPL RESEARCH REPORT K2-00 (3-02) |
State and National
Standardized Lactation Averages by Breed for Cows Calving in 2000
R.L. Powell and A.H. Sanders |
| AIPL RESEARCH REPORT K2-00 (3-02) |
State and National
Standardized Lactation Averages by Breed for Cows Calving in 2000
R.L. Powell and A.H. Sanders |
Data for the 2002 State and national lactation averages report were from calvings in 2000. National averages for some prior years, computed to reflect the change from reporting of crude protein to true protein, are also presented. This is the first report to include actual true protein measurements. Data collected prior to May 1, 2000 were adjusted to true protein basis by subtracting 0.19 percent from the crude protein percentage.
Yield data that are used in national genetic evaluations of dairy cattle and in other U.S. Department of Agriculture research originate from herds that are enrolled in the Dairy Herd Improvement program. The test-day data, used by the Animal Improvement Programs Laboratory to determine lactation records, are provided through dairy records processing centers.
Lactation records were calculated using the best prediction method and were standardized for age-parity, calving month, previous days open, and times milked per day. Records in progress and other records that were shorter than 305 days were extended to 305 days as part of the best prediction process. Component percentages were computed from average standardized yields for milk and components. Protein testing is at or near 100% except in California (85% for Holsteins).
Only data used in the calculation of national genetic evaluations are included in the State and national averages. Thus, records beyond fifth lactation or by cows that lacked a first lactation record were excluded.
The numbers of records and averages for yields and component percentages are in Tables 1 through 7 by State for Ayrshires, Brown Swiss, Guernseys, Holsteins, Jerseys, Milking Shorthorns, and Red and Whites. The numbers of records and national averages are in Table 8A-8F by breed for selected years.
Breed yields are different between this report and the herd-average report because this report uses standardized data, whereas herd averages are based on rolling actual data. Also, data for cows that calve in 2000 contribute to herd averages for 2000 and 2001. Finally, herd-average data do not have a restriction that they must be usable for national genetic evaluations. Relative yields among breeds will differ between the two reports because of breed differences in percentage of usable records and differences in age-parity factors.
Numbers of Jersey records increased by 6% to an all-time high. Brown Swiss and Milking Shorthorn numbers were nearly the same as for the previous year, while other breeds showed decreases. Holsteins declined 3%, Ayrshire 5%, and Guernsey and Red and White continued the trend of recent years, dropping 8%. Milk yield was about the same for Ayrshire, dropped 1% for Milking Shorthorn, and attained the highest averages ever for the other breeds. Fat and protein yields were also at all-time highs except for Ayrshire and Milking Shorthorn which were steady or dropped slightly (< 1%). Fat percentage in all breeds was fairly steady in recent years as was protein percentage for Ayrshire and Brown Swiss. Protein percentage continued to increase in other breeds, attesting to its increasing market value.
Changes in the numbers of records and average yields result from many factors. Genetic change is expected to have a positive effect on yield, whereas feed availability and other operating costs, milk and beef prices, Government programs, and characteristics of herds entering and leaving eligible testing programs can affect production averages in either direction.