Document Detail


Estrus synchronization in beef heifers with progestin-based protocols. I. Differences in response based on pubertal status at the initiation of treatment.
MedLine Citation:
PMID:  15451259     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Two progestin-based protocols for estrus synchronization in replacement beef heifers were compared on the basis of estrous response, interval to and synchrony of estrus, and pregnancy rate. The objective was to determine, whether addition of GnRH to a melengestrol acetate (MGA)-prostaglandin F2alpha (PGF2alpha) estrus synchronization protocol would improve synchrony of estrus without compromising fertility in yearling beef heifers. Heifers at two locations (Location 1, n = 60 and Location 2, n = 64) were assigned randomly to one of two treatments by breed and pubertal status. Heifers were defined as, pubertal when concentrations of progesterone in serum were elevated (> or = 1 ng/mL) in either one of two samples obtained 10 and 1 day prior to treatment initiation. Prior to MGA administration, 18/60 (30%) and 36/64 (56%) of the heifers at Locations 1 and 2, respectively, were pubertal. Heifers in both treatments were fed MGA (0.5 mg/head/day in 1.8 kg/head/day supplement) for 14 days followed by 25 mg of PGF2alpha i.m. (MGA-PGF2alpha) 19 days after MGA withdrawal (Day 33 of treatment). One-half of the heifers at each location received 100 microg of GnRH i.m. 12 days after MGA withdrawal (Day 26 of treatment; MGA Select). The control group received only MGA-PGF2alpha. Heifers were observed for signs of behavioral estrus continuously during daylight hours for 7 days beginning on the day PGF2alpha was administered. Heifers were inseminated 12 h after observed estrus. There was a treatment by location by pubertal status interaction (P < 0.05) for interval to estrus. Compared to the respective control treatment at each location, prepubertal heifers assigned to the MGA Select protocol at Location 1 had longer intervals to estrus, whereas at Location 2, prepubertal heifers assigned to the MGA-PGF2alpha protocol had longer intervals to estrus. The higher number of pubertal heifers at Location 2 was associated with a reduced variance in the interval to estrus among MGA Select treated heifers. Total estrous response and synchronized conception rates were similar between treatments at both locations. These data suggest that addition of GnRH to the MGA-PGF2alpha protocol may improve synchrony of estrus, however, the degree of synchrony may be influenced by pubertal status of heifers at the time treatments are imposed. Further studies are needed to define production systems in which the MGA Select protocol is warranted for use in beef heifers.
Authors:
S L Wood-Follis; F N Kojima; M C Lucy; M F Smith; D J Patterson
Related Documents :
11393219 - Use of buserelin to induce ovulation in the cyclic mare.
21453159 - Effect of intravenous administration of dextrose on coagulation in healthy dogs.
10783359 - A single mid-follicular dose of cdb-2914, a new antiprogestin, inhibits folliculogenesi...
9457949 - Double oocyte aspiration may be a solution for empty follicle syndrome: case report.
12597369 - Ovarian cyclicity in thyroid-suppressed ewes treated with propylthiouracil immediately ...
16895639 - Effect of an oral contraceptive pill on follicular development in ivf/icsi patients rec...
18519719 - Pharmacodynamics of minocycline against staphylococcus aureus in an in vitro pharmacoki...
21647339 - Clinical evaluation of xylazine-butorphanol-guaifenesin-ketamine as short-term tiva in ...
3877299 - Propofol ('diprivan') for continuous intravenous anaesthesia. a comparison with methohe...
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Theriogenology     Volume:  62     ISSN:  0093-691X     ISO Abbreviation:  Theriogenology     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-09-28     Completed Date:  2004-12-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0421510     Medline TA:  Theriogenology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1518-28     Citation Subset:  IM    
Affiliation:
Department of Animal Sciences, Patterson, S132 ASRC, University of Missouri Columbia, MO 65211, USA.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Animals
Cattle / physiology*
Diet
Dinoprost / administration & dosage
Estrus / physiology
Estrus Synchronization / methods*
Female
Gonadotropin-Releasing Hormone / administration & dosage
Pregnancy
Pregnancy Rate
Progesterone / blood
Progestins / administration & dosage*
Sexual Maturation*
Time Factors
Chemical
Reg. No./Substance:
0/Progestins; 33515-09-2/Gonadotropin-Releasing Hormone; 551-11-1/Dinoprost; 57-83-0/Progesterone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Influence of glucose and fructose in the extender during long-term storage of chilled canine semen.
Next Document:  Progesterone supplementation during the early fetal period reduces pregnancy loss in high-yielding d...