JDS
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Journal of Dairy Science Vol. 48 No. 2 222-227
© 1965 by American Dairy Science Association ®
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Gangwar, P. C.
Right arrow Articles by Evans, D. L.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Gangwar, P. C.
Right arrow Articles by Evans, D. L.

Reproductive and Physiological Responses of Holstein Heifers to Controlled and Natural Climatic Conditions1

P. C. Gangwar2, 3,, Cecil Branton and D. L. Evans

Department of Dairy Science, Louisiana Agricultural Experiment Station, Baton Rouge

ABSTRACT

Two groups (five animals each) of 12- to 15-month-old virgin Holstein heifers were used to evaluate the effects of natural and controlled hot and cool climatic conditions in a 180-day experiment on certain reproductive and physiological responses.

Under cool climatic conditions (62 to 65 F), the average length of the estrous cycle was 20 to 21 days, as compared with 25 and 21 days under controlled, cycled hot (75, 85, and 95 F), and natural summer climatic conditions, respectively. The difference in responses under hot and cool climatic conditions was highly significant (P < 0.01). Under spring, cycled hot, air conditioning, and natural summer climatic conditions the average duration of estrus was 20, 11, 20, and 14 hr, respectively. Thus, hot climatic conditions significantly (P < 0.01) depressed the length of the estrual period. The incidence of clinical anestrous was 33% among the heifers during the cycled, hot period (in climatic chamber). The intensity of estrus and post-ovulatory bleeding time were decreased under hot climatic conditions.

Thyroidal activity was depressed on the day of estrus in contrast to other days of the estrous cycle. Neutrophila, lymphopenia, and general leucocytosia (P < 0.01) were observed on the day of estrus.

FOOTNOTES

1 This investigation was supported financially by the Louisiana Artificial Breeding Cooperative, Inc., and the Louisiana Agricultural Experiment Station, Baton Rouge.

2 This paper is based on data from the senior author's doctoral dissertation.

3 Current address: New York Medical College, Flower and Fifth Avenue Hospitals, Fifth Avenue at One Hundred and Sixth Street, New York 29, New York.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 1965 by the American Dairy Science Association ®.