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Title: RELATIONS AMONG PTAS FOR SOMATIC CELL SCORES MILK YIELD AND LENGTH OF PRODUCTIVE LIFE

Author
item MCDANIEL, BEN - N CAROLINA STATE UNIV
item WILK, J - N CAROLINA STATE UNIV
item Vanraden, Paul
item SCHUTZ, MICHAEL - AIPL USDA

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The value of predicted transmitting abilities (PTA's) of bulls for somatic cell score (SCS) and milk yield for predicting PTA's for productive life (PL) was examined. All PTA's used were those published by USDA. Only 940 Holstein and 94 Jersey bulls with highly reliable PTA's for SCS and PL were included. For Holsteins, correlations adjusted for birth year were -.35 between SCS and PL, .34 between milk and PL, and .15 between SCS and milk. Including both milk and SCS simultaneously increased correlations with PL to .39 for SCS and .35 for milk. Values for R2 were .12 for SCS alone and .11 for milk alone but .27 when both were included. Partial regressions indicated a 3.1-month increase in PL for a reduction of one unit of PTA for SCS. Values for Jerseys were lower for SCS and higher for milk but showed the same trends. All correlations and regressions in both breeds were real (P<.05). These results show that the newest PTA available for dairy cattle, PTA SCS, is more valuable economically than many others used to choose bulls. Among AI bulls with the same levels of PTA's for yields, desirable (low) PTA's for SCS are more predictive of PL than generally thought. The PTA for SCS of first lactation cows could be used together with those for milk and type to improve predictions of PL of their sires