Bilby_3385 - J. Dairy Sci. 89:33753385 American Dairy...

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Unformatted text preview: J. Dairy Sci. 89:33753385 American Dairy Science Association, 2006. Pregnancy, Bovine Somatotropin, and Dietary n-3 Fatty Acids in Lactating Dairy Cows: II. Endometrial Gene Expression Related to Maintenance of Pregnancy T. R. Bilby,* A. Guzeloglu, L. A. MacLaren, C. R. Staples,* and W. W. Thatcher* 1 *Department of Animal Sciences, University of Florida, Gainesville 32611-0910 Department of Obstetrics and Gynaecology, Faculty of Veterinary Medicine, Selcuk University, Konya, Turkey 42075 Department of Plant and Animal Sciences, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada ABSTRACT The objectives were to examine the effects of bovine somatotropin (bST), pregnancy, and dietary fatty acids on expression of key endometrial genes and proteins regulating prostaglandin synthesis in lactating dairy cows. Two diets were fed, at about 17 d in milk (DIM), in which oil of whole cottonseed (control diet) was com- pared with calcium salts of fish oil-enriched lipid (FO). Ovulation was synchronized in cows with a presynchro- nization plus Ovsynch protocol and cows were insemi- nated artificially or not inseminated on d 0 (d 0 = time of synchronized ovulation; 77 12 DIM). On d 0 and 11, cows received bST (500 mg) or no bST, and were slaughtered on d 17 to recover uterine secretions and endometrial tissue. Number of cows in the control diet: 5 bST-treated cyclic (bST-C), 5 non-bST-treated cyclic (no bST-C), 4 bST-treated pregnant (bST-P), and 5 non- bST-treated pregnant (no bST-P) cows and in the FO diet: 4 bST-treated FO-cyclic (bST-FO-C) and 5 non- bST-treated cyclic (no bST-FO-C) cows. The FO diet increased progesterone receptor (PR) mRNA, and treat- ment with bST increased PR mRNA concentration in endometrium of no bST-C, but not in no bST-FO-C or no bST-P cows. Concentrations of estrogen receptor- (ER ) mRNA and protein, and oxytocin receptor (OTR) mRNA were decreased in no bST-P cows compared with no bST-C cows. Treatment with bST tended to increase OTR and ER mRNA concentrations in cyclic cows fed control or FO diets. Immunohistochemistry demon- strated effects of bST, FO, and pregnancy on distribu- tions of ER and PR proteins in endometrium. Preg- nancy and FO feeding decreased ER abundance in luminal epithelium. Prostaglandin H synthase-2 (PGHS-2) protein was elevated in pregnant cows and localized to the luminal epithelium. Both FO and bST treatments reduced staining intensity of PGHS-2 pro- Received October 21, 2005. Accepted April 5, 2006. 1 Corresponding author: thatcher@animal.ufl.edu 3375 tein. Concentrations of prostaglandin E synthase mRNA were elevated in either cyclic or pregnant cows in response to bST, whereas bST decreased prostaglan- din F synthase mRNA in pregnant cows. Uterine lumen fluids had more PGF 2 and prostaglandin E 2 in preg- nant than cyclic cows. Uterine lumen fluids of bST-P cows contained more prostaglandin E 2 than those from no bST-P cows. In summary, both pregnancy and bSTno bST-P cows....
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This note was uploaded on 01/15/2012 for the course ANS 3384 taught by Professor Olson during the Spring '09 term at University of Florida.

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Bilby_3385 - J. Dairy Sci. 89:33753385 American Dairy...

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