Within-Herd Effects of Age at Test Day and Lactation Stage on Test-Day Yields
نویسندگان
چکیده
منابع مشابه
Within-herd effects of age at test day and lactation stage on test-day yields.
Variance ratios were estimated for random within-herd effects of age at test day and lactation stage, on test-day yield and somatic cell score to determine whether including these effects would improve the accuracy of estimation. Test-day data starting with 1990 calvings for the entire US Jersey population and Holsteins from California, Pennsylvania, Wisconsin, and Texas were analyzed. Test-day...
متن کاملDeriving Lactation Yields from Test-Day Yields Adjusted for Lactation Stage, Age, Pregnancy, and Herd Test Date
Lactation records for milk, fat, and protein yields were calculated from test-day data adjusted for the effects of lactation stage, age, previous days open, days pregnant, and test-day class (herd, test date, and milking frequency). Those lactation records reflect the improved accounting of environmental effects from a test-day model and can be combined with historical lactation records. Test-d...
متن کاملRelationship of test-day somatic cell score with test-day and lactation milk yields.
To determine the relationship of test-day (TD) somatic cell score (SCS) to TD and lactation milk yields, 1,320,590 records from Holstein first and second calvings from 1995 through 2002 were examined. All lactations had recorded yield and SCS for at least the first 4 TD. Least square analyses were conducted for yields on TD 2 through 10 within herd and cow. The model included regressions on cur...
متن کاملEstimating Effects of Permanent Environment, Lactation Stage, Age, and Pregnancy on Test-Day Yield
Test-day variances for permanent environmental effects within and across parities were estimated along with lactation stage, age, and pregnancy effects for use with a test-day model. Data were test-day records for calvings since 1990 for Jerseys and for Holsteins from California, Pennsylvania, Texas, and Wisconsin. Single-trait repeatability models were fitted for milk, fat, and protein test-da...
متن کاملLactation yields and accuracies computed from test day yields and (co)variances by best production.
Lactation records are calculated from data on milk, fat, and protein obtained from one or more milkings on several days during the lactation. The test interval method, which estimated missing daily milk yields by simple interpolation, was used for many years for standard monthly data but may not be as useful for the wider variety of test plans now being proposed. More accurate 305-d yields can ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Journal of Dairy Science
سال: 2003
ISSN: 0022-0302
DOI: 10.3168/jds.s0022-0302(03)73983-6