J. Anim Sci.
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J. Anim Sci. 1982. 54:302-308.
© 1982 American Society of Animal Science
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Variables Associated with Peripartitum Traits in Dairy Cows. IX. Relationship of Season and other Factors to Blood Plasma Concentrations of Progesterone and the Estrogens1,2,

R. E. Erb3, B. P. Chew4, P. V. Malven, T. S. Stewart and M. Frances D'Amico5

Purdue University,6, West Lafayette, IN 47907

Abstract

Least-squares associations of month, average daily temperature, photoperiod (h daylight/24 h) and other factors with plasma concentrations of hormones during the prepartum period were examined in 172 Holstein cows and heifers. The data were summarized and expressed as values for prepartum d 7, 4 and 1, which represented the means for d 8 to 6, 5 to 3, and 2 to 0, respectively. All animals calved during a period of 19 consecutive months. Across days, least-squares means for plasma hormones were 4.0 ng/ml for progesterone (P4), 232 pg/ml for estradiol-17β (Eβ), 478 pg/ml for estradiol-17{alpha} (E{alpha}), 1,970 pg/ml for estrone (E1) and 2,680 pg/ml for total estrogen (TE; sum of Eβ, E{alpha} and E1). Variations in plasma concentrations of certain steroids were associated (P<.05 to P<.01) with diet group (Eβ), calf sex (TE), prepartum day (all hormones), month (Eβ, E{alpha}) and linear covariates of cow weight (Eβ, E{alpha}) calf birth weight (Eβ, E{alpha}, E1 TE), temperature (P4, Eβ and photoperiod (P4, Eβ). The independent linear regressions for temperature and for photoperiod in prediction equations for each plasma hormone were always inversely related. The combined use of these regressions only partially accounted for fluctuations in the least-squares monthly means for hormones. Changes in least-squares monthly means for P4, Eβ and E{alpha} tended to be only partially parallel during the year. Nonparallel trends among hormones were most apparent during May to July (decreasing P4 but increasing Eβ and E{alpha}), September to November (decreasing P4 and Eβ but increasing E{alpha}) and January and February (only E{alpha} elevated). We hypothesize that seasonal differences in parturient traits reported for cows may be explained in part by the seasonally associated nonparallel changes in plasma concentrations of P4, Eβ and E{alpha}

Footnotes

1 Journal Paper No. 8107, Purdue Univ. Agr. Exp. Sta. A contribution to project NC-113, Methods for Improvement of Fertility in Cows Postpartum.

2 The authors thank Dr. Claudie N. Zamet for assistance with sampling and observation of animals, and Mrs. Doris Blair for assaying the plasma hormones.

3 3300 Carpenter Road SE, #85, Olympia, WA 98503.

4 Dept. of Anim. Sci., Washington State Univ., Pullman 99164

5 6600 Whispering Hills Drive, Evansville, IN 47712.

6 A contribution from the Dept. of Anim. Sci.






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Copyright © 1982 by the American Society of Animal Science.