Location: Location not imported yet.Title: Reproductive trends of dairy herds in the United States) Author
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/25/2008
Publication Date: 7/11/2008
Citation: Norman, H.D., Wright, J.R., Hubbard, S.M., Kuhn, M.T., Miller, R.H. 2008. Reproductive trends of dairy herds in the United States. Journal of Dairy Science. 91(E-Suppl. 1):7(abstr. T18). Interpretive Summary:
Technical Abstract: Trends for reproductive traits were examined for U.S. Holstein and Jersey herds enrolled in Dairy Herd Information testing. Traits were days from calving to first service (DFS) and to last service, 70-d nonreturn rates (NRR) and conception rates (CR) for first through fifth services, days open, gestation length, and services per lactation for breedings from 1996 through 2005. Holstein DFS increased from 89 in 1996 to 92 in 2001 and then declined to 86 in 2005; no trend was observed for Jersey DFS. First-service NRR declined from 54 and 57% in 1996 to 46 and 52% in 2005 for Holsteins and Jerseys, respectively; first-service CR declined from 36 and 39% to 30 and 35%. As expected from the NRR decline, services per lactation increased from 2.1 in 1996 to 2.6 in 2005 for Holsteins and from 2.0 to 2.4 for Jerseys. Days to last service also increased by 16 d for both breeds. Days open increased during early years but have stabilized for both breeds. Gestation length showed no change across time for either breed. Data from 2005 breedings were examined for the same traits by parity for both breeds and by geographic region for Holsteins. Later parities (>5) were associated with longer DFS, lower first-service NRR, and increased first-service CR compared with early parities (1 and 2) for both breeds; services per lactation remained fairly constant for Holsteins and increased slightly with parity for Jerseys. For both breeds, NRR for first and second services and CR for each service through fourth declined across parities. Southwest Holsteins had the fewest DFS (73 d) and lowest first-service NRR (36%); the Mountain region had the greatest DFS (93 d) and the highest NRR (48%). Southeast Holsteins had the lowest first-service CR (23%) and fewest services per lactation (3.0); the Northeast had the highest CR (31%) and the fewest services (2.6). Trends likely were impacted by producer preference for animal age for herd retention and increased use of estrous synchronization and timed artificial insemination.