Reduced postpartum anestrus of suckled beef cows treated with microencapsulated luteinizing hormone-releasing hormone analog.

S. Roberge, R. D. Schramm, Andrew V Schally, J. J. Reeves

Research output: Contribution to journalArticle

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Abstract

This study evaluated the effect of microencapsulated LHRH agonist (D-Trp6-LHRH) on gonadotropin release and occurrence of estrus in early postpartum beef cows. Angus cows (n = 54) were assigned randomly to two treatment groups at d 5 postpartum. Group 1 received a single i.m. injection of D-Trp6-LHRH (LHRH-A) encapsulated in poly-DL-lactide-coglycolide, calculated to release 15 micrograms of LHRH-A per day for 30 d (n = 23). Group 2 received vehicle only (control, n = 31). Blood samples (15-min intervals for 6 h) were obtained on d 5, 10, 20, 30, and 40 postpartum for evaluation of LH and FSH concentrations (n = 12 per group). Days to first postpartum estrus were reduced by treatment with LHRH-A (Group 1, 43.7 +/- 4.2 d vs Group 2, 55.9 +/- 4.7 d; P < .05). However, days to conception were similar between groups (68.9 +/- 7.9 vs 76.7 +/- 6.7 d, respectively). On the day of treatment, cows treated with LHRH-A had higher mean concentrations of LH and FSH than did controls (8.3 +/- 1.4 vs 2.0 +/- .4 ng/mL for LH and 211.0 +/- 8.6 vs 51.2 +/- 2.7 ng/mL for FSH (P < .05). There were no differences in mean concentrations of LH or FSH between treatment groups on d 10, 20, 30, and 40 postpartum. Cows given LHRH-A had more (P < .05) LH pulses on d 10 and 30 postpartum than did controls. This study demonstrated that microencapsulated D-Trp6-LHRH reduced the postpartum anestrous interval in suckled beef cows.

Original languageEnglish
Pages (from-to)3825-3830
Number of pages6
JournalJournal of Animal Science
Volume70
Issue number12
StatePublished - Dec 1 1992
Externally publishedYes

Fingerprint

Anestrus
postpartum interval
synthetic hormones
beef cows
gonadotropin-releasing hormone
Gonadotropin-Releasing Hormone
Postpartum Period
Estrus
cows
estrus
gonadotropin release
Angus
Therapeutics
agonists
Gonadotropins
injection

ASJC Scopus subject areas

  • Animal Science and Zoology

Cite this

Reduced postpartum anestrus of suckled beef cows treated with microencapsulated luteinizing hormone-releasing hormone analog. / Roberge, S.; Schramm, R. D.; Schally, Andrew V; Reeves, J. J.

In: Journal of Animal Science, Vol. 70, No. 12, 01.12.1992, p. 3825-3830.

Research output: Contribution to journalArticle

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