IMPROVING GENETIC PREDICTIONS FOR DAIRY ANIMALS USING PHENOTYPIC AND GENOMIC INFORMATION
Title: Reproductive status of Holstein and Jersey cows in the United States
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 2009
Publication Date: July 1, 2009
Citation: Norman, H.D., Wright, J.R., Hubbard, S.M., Miller, R.H., Hutchison, J.L. 2009. Reproductive status of Holstein and Jersey cows in the United States. Journal of Dairy Science. 92(7):3517-3528.
Interpretive Summary: US dairy records from a number of sources were used to examine trends in reproductive traits, including days to first breeding, 70 day non-return rates, conception rates, numbers of services per lactation, days open, and calving intervals. Some traits were examined by service number, parity, and region. There is evidence that genetics and new technology are impacting the reproductive traits over time.
Reproductive information from USDA’s national dairy database since 1996 was used to provide yearly means in 8 traits in the Holstein and Jersey breeds. Respectively, data for Holsteins and Jerseys were from 20,746 and 1963 herds, 3,645,987 and 184,398 cows, 7,107,057 and 387,441 lactations, and 15,851,120 and 776,364 inseminations. Detail information was given for some reproductive traits by parity and service number for both breeds, as well as by geographical region in Holsteins. The Northeast had the highest CR (31%) and the fewest breedings per lactation (2.6); the Southeast had the lowest CR (23%) and the most breedings per lactation (3.0). Although days to first breeding increased in Holstein between 1996 and 2001, they declined by 6 d thereafter. First service 70 d non-return rate and conception rate declined in both breeds by 5 to 10%, while number and services per lactation increased by 0.5. Days open increased across early years in both breeds, but now appears to have stabilized. Later parities had longer days to first breeding, lower first service 70-d non-return rate and conception rate compared to early parities in both breeds. In spite of this, number of services per lactation remained fairly constant for Holstein and increased slightly in Jerseys, perhaps reflecting a difference in willingness to keep rebreeding. First-and 2nd- service 70-d non-return rate declined as parity increased for both breeds. Second-service conception rate was highest within parity for both breeds, 1 to 2% above first-service conception. Conception rate for specific services generally declined with parity for both breeds. Trends appear to be impacted by geographical region, producer preferences, and increased use of synchronized breedings.