|
|
||||||||
1 Department of Animal Science, University of Zimbabwe, Mount Pleasant, Harare
2 Department of Animal Science, North Carolina State University, Raleigh 27695
Effects of days dry and previous and current days open on milk yields during the first three lactations were determined for Holsteins from Zimbabwe and North Carolina. The animal models used included animal; permanent environmental effects of cows for herd-year, month of calving, age, current days open, and DIM; and the inverse of additive numerator genetic relationships. Model 1 for first lactations included only these effects, but Model 2, the animal model for later lactations, included these effects plus previous days open, previous days dry, and previous milk yield. The dependent variable in both models was unadjusted milk yield for the lactation. Current and previous days open, previous days dry, and DIM were also fitted as dependent variables with Models 1 and 2, except for previous milk yield, when appropriate. As current days open increased, milk yield rose, regardless of milk yield during prior lactations. Milk yields were reduced for lactations following <60 d dry and showed little advantage for longer dry periods. The effects of previous days open are real but are overestimated unless permanent environmental effects of cows are considered simultaneously. The heritabilities and repeatabilities of current and previous days open and previous days dry were higher for cows in Zimbabwe than for those in North Carolina. Results suggest that, to obtain unbiased estimates of breeding values of sires and cows, yield data should be adjusted for the environmental effects of days dry as well as those of previous and current days open.
Key Words: days open days dry Zimbabwe Holsteins
Submitted on May 30, 1995
Accepted on December 4, 1995
This article has been cited by other articles:
![]() |
M. S. Gulay, M. J. Hayen, H. H. Head, and K. C. Bachman Short communication: Effect of estrogen supplemented at dry-off on temporal changes in concentrations of lactose in blood plasma of Holstein cows J Dairy Sci, August 1, 2009; 92(8): 3815 - 3818. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Bohmanova, J. Jamrozik, and F. Miglior Effect of pregnancy on production traits of Canadian Holstein cows J Dairy Sci, June 1, 2009; 92(6): 2947 - 2959. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Pezeshki, J. Mehrzad, G. R. Ghorbani, H. R. Rahmani, R. J. Collier, and C. Burvenich Effects of Short Dry Periods on Performance and Metabolic Status in Holstein Dairy Cows J Dairy Sci, December 1, 2007; 90(12): 5531 - 5541. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. T. Kuhn, J. L. Hutchison, and H. D. Norman Dry Period Length in US Jerseys: Characterization and Effects on Performance J Dairy Sci, April 1, 2007; 90(4): 2069 - 2081. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. T. Kuhn, J. L. Hutchison, and H. D. Norman Dry Period Length to Maximize Production Across Adjacent Lactations and Lifetime Production J Dairy Sci, May 1, 2006; 89(5): 1713 - 1722. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. T. Kuhn and J. L. Hutchison Methodology for Estimation of Days Dry Effects J Dairy Sci, April 1, 2005; 88(4): 1499 - 1508. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. R. Rastani, R. R. Grummer, S. J. Bertics, A. Gumen, M. C. Wiltbank, D. G. Mashek, and M. C. Schwab Reducing Dry Period Length to Simplify Feeding Transition Cows: Milk Production, Energy Balance, and Metabolic Profiles J Dairy Sci, March 1, 2005; 88(3): 1004 - 1014. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. T. Kuhn, J. L. Hutchison, and H. D. Norman Characterization of Days Dry for United States Holsteins J Dairy Sci, March 1, 2005; 88(3): 1147 - 1155. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. R. Grummer and R. R. Rastani Why Reevaluate Dry Period Length? J Dairy Sci, July 1, 2004; 87(13_suppl): E77 - 85. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. C. Bachman and M. L. Schairer Invited Review: Bovine Studies on Optimal Lengths of Dry Periods J Dairy Sci, October 1, 2003; 86(10): 3027 - 3037. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. S. Gulay, M. J. Hayen, K. C. Bachman, T. Belloso, M. Liboni, and H. H. Head Milk Production and Feed Intake of Holstein Cows Given Short (30-d) or Normal (60-d) Dry Periods J Dairy Sci, June 1, 2003; 86(6): 2030 - 2038. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |