| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Animal Sciences, University of Arizona, Tucson 85721
Records representing 19,266 Holstein cows from Arizona DHIA data over a 5-yr period were analyzed to determine the effects of season and lactation number on milk production and reproduction. Seasons were winter (December, January, and February), spring (March, April, and May), summer (June, July, and August), and fall (September, October, and November). Traits analyzed by least squares ANOVA were 305-d FCM, complete lactation milk, calving interval, and services per conception. All sources of variation were significant except the interaction between lactation number and season of calving for complete lactation milk. Milk production was depressed for cows calving in summer and fall. First lactation cows had lowest milk production, and highest production occurred in either lactation 4 or 5. Cows calving in spring and summer had reduced reproductive performance, as measured by calving interval and services per conception. First lactation cows had lowest values for both reproductive traits. Previous days dry was negatively related to milk production for spring calvings but was positively related for all other seasons. Cows with higher milk production had reduced reproductive performance. Partial regression coefficients for calving interval and services per conception were 12 d and .25 services per conception per 1000 kg of 305-d FCM, respectively. Despite the negative effects of thermal stress, milk production and fertility in this study were not depressed as severely as in previous research reported from Arizona. Calving schedules may be adjusted to minimize the adverse effect of heat stress.
Key Words: heat stress • reproduction • production • lactation number
Submitted on January 2, 1992
Accepted on May 18, 1992
This article has been cited by other articles:
|
|
 |
|
  F. Sithole, I. Dohoo, K. Leslie, L. DesCoteaux, S. Godden, J. Campbell, H. Stryhn, and J. Sanchez Effect of Eprinomectin Treatment at Calving on Milk Production in Dairy Herds with Limited Outdoor Exposure J Dairy Sci, March 1, 2005; 88(3): 929 - 937. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. B. Garcia-Peniche, B. G. Cassell, R. E. Pearson, and I. Misztal Comparisons of Holsteins with Brown Swiss and Jersey Cows on the Same Farm for Age at First Calving and First Calving Interval J Dairy Sci, February 1, 2005; 88(2): 790 - 796. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Guo, E. Russek-Cohen, M. A.Varner, and R. A. Kohn Effects of Milk Urea Nitrogen and Other Factors on Probability of Conception of Dairy Cows J Dairy Sci, June 1, 2004; 87(6): 1878 - 1885. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. R. St-Pierre, B. Cobanov, and G. Schnitkey Economic Losses from Heat Stress by US Livestock Industries J Dairy Sci, July 1, 2003; 86(13_suppl): E52 - 77. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. R. Jordan Effects of Heat Stress on Reproduction J Dairy Sci, July 1, 2003; 86(13_suppl): E104 - 114. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
