Document Detail


Size of ovulatory follicles in cattle expressing multiple ovulations naturally and its influence on corpus luteum development and fertility.
MedLine Citation:
PMID:  19684271     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Long-term genetic selection of cattle for fraternal twins has increased the frequency of twin and triplet ovulations. In contrast, the ratio of fetal numbers to ovulation sites in pregnant females with twin (0.83) or triplet (0.73) ovulations is <1.0 and the number of calves per parturition is 1.6 and 2.0, respectively. Failure of individual twin or triplet ovulations to yield a conceptus in fertile females indicates a significant contribution of ovulation or oocyte anomalies to increased fertilization failure or early embryonic mortality. The present objective was to identify physiological traits affecting conception in cyclic cattle expressing multiple ovulations naturally, including the effect of ovulation rate on follicle or corpus luteum (CL) size, and their relationship to conception. Diameter of the individual ovulatory follicles was measured by transrectal ultrasonography at AI and ranged from 8 to 30 mm, with a trend for diameter of the individual follicles, and associated CL, to decrease with increasing ovulation rate. Independent of ovulation rate, ovulatory follicles were smaller (P < 0.05) for nulliparous heifers (1.5 yr) compared with parous cows (> or =2.5 yr). Pregnancy and fetal status were diagnosed by transrectal ultrasonography between 42 and 72 d after AI. Fertility was reduced (P < 0.01) for small twin or triplet ovulatory follicles (8 to 8.9 mm vs. 10 to 17.9 mm diam.), whereas fertility in monovular females was reduced (P < 0.01) for large ovulatory follicles (> or =22 vs. 14 to 17.9 mm). Plasma progesterone concentrations increased with ovulation rate and were correlated positively with total CL or ovulatory follicle volume per female, indicating that CL size and function were influenced by the size of the follicle of origin. Progesterone was greater (P < 0.05) in the blood of nulliparous heifers compared with parous cows. The increased proportion of small ovulatory follicles associated with twin and triplet ovulations indicates that some ovulatory follicles were either selected to ovulate at a lesser stage of maturity or rescued while undergoing atresia, thus compromising oocyte competency or ovulation. Of greatest importance for reduced fertility was the greater incidence of pregnancy losses occurring in the middle of gestation in females gestating 2 or more fetuses as an apparent effect of uterine crowding, especially when 2 or more fetuses were contained within 1 uterine horn.
Authors:
S E Echternkamp; R A Cushman; M F Allan
Publication Detail:
Type:  Journal Article     Date:  2009-08-14
Journal Detail:
Title:  Journal of animal science     Volume:  87     ISSN:  1525-3163     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-10-20     Completed Date:  2010-01-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3556-68     Citation Subset:  IM    
Affiliation:
USDA-ARS, US Meat Animal Research Center, Clay Center, NE 68933-0166, USA. Sherrill.Echternkamp@ars.usda.gov
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MeSH Terms
Descriptor/Qualifier:
Animals
Breeding
Cattle / physiology*
Corpus Luteum / growth & development,  physiology*
Female
Fertility / physiology
Insulin-Like Growth Factor I / analysis
Ovarian Follicle / anatomy & histology,  physiology*
Ovulation / physiology*
Pregnancy
Pregnancy, Multiple / physiology
Progesterone / blood
Twins, Dizygotic / physiology
Chemical
Reg. No./Substance:
57-83-0/Progesterone; 67763-96-6/Insulin-Like Growth Factor I

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


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