Document Detail


Short communication: suppression of estrous cycles in lactating cows has no effect on milk production.
MedLine Citation:
PMID:  16428633     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The decline in milk yield observed after peak production in dairy animals results from apoptotic death of mammary epithelial cells. In cows, this decrease in milk yield can be accelerated by injection of 17beta-estradiol, thus evoking a possible role of estrogens in the regulation of bovine mammary gland involution. In nonpregnant cows, mammary involution could be induced or enhanced by the return of estrous cycles and the accompanying cyclic peaks of estrogen concentration in the serum of lactating animals. To test this hypothesis, we inserted implants of a GnRH agonist, deslorelin, in an ear of each cow (n = 10) on d 10 and 100 of lactation, to temporarily suppress the return of ovarian cycles. Cows were studied from calving to d 210 of lactation. Deslorelin had no impact on feed intake or animal health. Deslorelin significantly reduced serum concentrations of 17beta-estradiol and progesterone as compared with untreated cows (n = 10). Deslorelin had no effect on milk fat and protein, whereas milk lactose content was lower in treated cows than in control cows on d 100 of lactation. Finally, there was no difference in milk production between the 2 groups of cows. These results are consistent with previous observations that showed that delaying estrous cycles after calving had no effect on milk yield and they extend those observations to late lactation. Based on milk production data, the estrogen profiles associated with recurring estrous cycles apparently do not cause bovine mammary tissue to undergo gradual involution.
Authors:
L Delbecchi; P Lacasse
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of dairy science     Volume:  89     ISSN:  1525-3198     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2006 Feb 
Date Detail:
Created Date:  2006-01-23     Completed Date:  2006-05-05     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  636-9     Citation Subset:  IM    
Affiliation:
Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, 2000 Rte 108 East Lennoxville, QC, Canada, J1M 1Z3. delbecchil@agr.gc.ca
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MeSH Terms
Descriptor/Qualifier:
Animals
Cattle / physiology*
Drug Implants
Estradiol / blood
Estrous Cycle / drug effects*,  physiology*
Fats / analysis
Female
Gonadotropin-Releasing Hormone / agonists
Lactation / physiology*
Lactose / analysis
Milk / chemistry
Milk Proteins / analysis
Progesterone / blood
Triptorelin / administration & dosage,  analogs & derivatives
Chemical
Reg. No./Substance:
0/Drug Implants; 0/Fats; 0/Milk Proteins; 33515-09-2/Gonadotropin-Releasing Hormone; 50-28-2/Estradiol; 57-83-0/Progesterone; 57773-63-4/Triptorelin; 63-42-3/Lactose; 70235-53-9/deslorelin

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


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