HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Mollett, T. A. Articles by Malven, P. V. Search for Related Content PubMed PubMed Citation Articles by Mollett, T. A. Articles by Malven, P. V.

Changes in Estrogen, Progesterone, Prolactin and Lactation Traits Associated with Injection of Estradiol-17ß and Progesterone into Lactating Cows^{1, 2,}

Purdue University, West Lafayette, Indiana 47907

Abstract

Eight nonpregnant dairy cows, one dry and seven producing daily 10 to 22 kg of 4.0% fat-corrected milk (FCM), were subcutaneously injected 15 times at 12-hr intervals (first injection—Day 0) with a mixture of estradiol-17ß (E₂ß) and progesterone (P) to evaluate effects on lactation and milk composition. Each injected dose contained .05 mg of E₂ß and .125 mg of P per kilogram of body weight.

Average daily yield of FCM was depressed from 14 kg on Day 0 to 4 kg on Day 18 (P<.01) and then increased to average of pretreatment rates by Day 60. Compared to pretreatment, subsequent lactation was not enhanced in three cows lactating pretreatment due to calving and was enhanced in two of four cows lactating pretreatment due to treatment with E₂ß and P. Average milk lactose concentration was lowest on Day 18 and percentages of fat and total protein were highest on Day 20 as compared to Days 0, 43 or 50 (P<.05). Changes in milk composition caused by treatment with E₂ß and P were characteristic of normal mammary gland regression and subsequent parturient lactogenesis. Concentrations of total free estrogen and progesterone in plasma were elevated during treatment (Days 5 and 8) and each was decreased on Day 16 (P<.05). Concentration of estrogen in milk was increased about 10-fold on Days 5 and 8 as compared to Day 0 (P<.05). On Day 16 and thereafter, milk estrogen concentrations and total secreted were nonsignificantly different from Day 0. Even on Day 5 of treatments, only .007% of the injected E₂ß was recovered in milk. Blood and milk estrogen concentrations were correlated (P<.01). Compared to Day 0, average plasma prolactin was elevated on the day that milk yield in each cow increased at least 1 kg (P<.05).

¹ Journal Paper 5688, Purdue University Agriculture Experimental Station, West Lafayette, Indiana 47907.

² The authors are indebted to Mrs. Doris Blair, Miss Mary Ann Escasa and Mr. Lester Martin for assistance with laboratory assays and to Mr. C. M. Brown, Jr. for assistance with experimental animals.

³ Present address: Department of Biology, West Virginia University, Morgantown.

This article has been cited by other articles:

				L. Delbecchi and P. Lacasse Short Communication: Suppression of Estrous Cycles in Lactating Cows Has No Effect on Milk Production J Dairy Sci, February 1, 2006; 89(2): 636 - 639. [Abstract] [Full Text] [PDF]