Manipulation of Ovarian Function for the Reproductive Management of Dairy Cows     

Thatcher  W.W.  Bartolome  J.A.  Sozzi  A.  Silvestre  F.  Santos  J.E.P. 《Veterinary research communications》2004,28(1):111-119

Veterinary Research Communications -  相似文献   

Effects of thermal stress and epinephrine on uterine blood flow in ewes     

H Roman-Ponce  W W Thatcher  D Caton  D H Barron  C J Wilcox 《Journal of animal science》1978,46(1):167-174

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Effect of day of the estrous cycle at the initiation of a timed artificial insemination protocol on reproductive responses in dairy heifers   总被引：1，自引：0，他引：1  

Moreira F  de la Sota RL  Diaz T  Thatcher WW 《Journal of animal science》2000,78(6):1568-1576

Our objectives were to identify stages of the estrous cycle at which initiation of a timed artificial insemination (Ovsynch/TAI) protocol may reduce pregnancy rates and to monitor ovarian follicle dynamics and corpus luteum development after initiation of the Ovsynch/TAI protocol at different stages of the cycle. Cycling Holstein heifers (n = 24) were injected twice with prostaglandin F2alpha to induce estrus and were scanned by ovarian ultrasonography to determine the day of ovulation (d 0). Heifers were assigned to initiate the Ovsynch/TAI protocol at d 2 (n = 5), 5 (n = 5), 10 (n = 4), 15 (n = 5), or 18 (n = 5) of the cycle. The Ovsynch/TAI was initiated with an injection of gonadotropin-releasing hormone agonist followed 7 d later with an injection of prostaglandin F2alpha. At 36 h after injection of prostaglandin F2alpha, heifers were injected with gonadotropin-releasing hormone agonist and inseminated 16 h later. Heifers were scanned daily during the Ovsynch/TAI protocol and every other day after insemination until 16 d later. Blood samples were collected daily starting at the 1st day heifers were scanned and continued until 16 d after insemination. Initiation of the Ovsynch/TAI protocol at d 15 of the estrous cycle caused heifers to ovulate prior to insemination. A shortened return to estrus (< 16 d) was caused by ovulation failure to the second gonadotropin-releasing hormone injection, by incomplete regression of the corpus luteum, and by short life-span of the induced corpus luteum. Day of the cycle in which the Ovsynch/TAI protocol is initiated affects dynamics of follicular development, plasma progesterone profiles, and occurrence of premature ovulation. Size of the pre-ovulatory follicle was associated positively with subsequent progesterone concentrations following insemination.  相似文献   

Intracellular regulation of endometrial PGF(2a) and PGE(2) production in dairy cows during early pregnancy and following treatment with recombinant interferon-tau     

Arnold DR  Binelli M  Vonk J  Alexenko AP  Drost M  Wilcox CJ  Thatcher WW 《Domestic animal endocrinology》2000,18(2):199-216

Objectives were to examine how the conceptus and recombinant bovine interferon-tau (rbIFN-tau) regulate intracellular components of the PGF(2a) synthetic pathway and to determine if arachidonic acid (AA) is limiting in endometrial tissue of pregnant cows. In Experiment 1, uteri were collected from either cyclic or pregnant dairy cows on Day 17 post-estrus. Intercaruncular explants were dissected and incubated for 60 min to quantify PGF(2a) production in response to oxytocin (10(-6) M), A23187 (10(-5) M), melittin (10(-5) M), and phorbol 12, 13 dibutyrate (PDBu, 10(-6) M). Additional explants from the same cows were incubated for 24 h with and without AA. Oxytocin and A23187 did not stimulate PGF(2a) in explants from either cyclic or pregnant cows. Both PDBu, melittin, and A23187 + melittin stimulated PGF(2a) production in explants of cyclic cows, but not in explants of pregnant cows. The addition of AA to explant cultures for 24 hr did not increase PGF(2a) production during a subsequent 60-min incubation. In Experiment 2, explants were collected from cows that received intrauterine infusions of either BSA (1.9 mg/1.2 ml) or rbIFN-tau (0.2 mg rbIFN-tau + 1.7 mg BSA/1.2 ml) twice a day from Days 14 to 17 of the estrous cycle. Treatments of rbIFN-tau attenuated PGF(2a) secretion induced by in vitro PDBu and A23187 treatments. However, rbIFN-tau treatment in vivo had no effect on the in vitro induction of PGF(2a) secretion by melittin. IFN-tau may regulate the PGF(2a) synthetic pathway by reducing activity of PKC or PKC mediated events.  相似文献   

Nutritional factors in bovine gastrointestinal disease     

C N Niederman  C D Thatcher  B Welker 《Veterinary Clinics of North America: Food Animal Practice》1990,6(2):265-306

Gastrointestinal disorders may be prevented through proper nutrition. Attention should be placed on establishing optimum feeding programs for cattle in all stages of the life and production cycle. Normal reticuloruminal development in calves and maintenance of gastrointestinal function in adult cattle is dependent upon adequate nutrition. Nutrition is also an important part of therapy of many gastrointestinal disorders.  相似文献   

Evaluation of the efficacy of prophylactic hoof health examination and trimming during midlactation in reducing the incidence of lameness during late lactation in dairy cows     

Hernandez JA  Garbarino EJ  Shearer JK  Risco CA  Thatcher WW 《Journal of the American Veterinary Medical Association》2007,230(1):89-93

OBJECTIVE: To assess the efficacy of prophylactic hoof health examination and trimming during midlactation at reducing the incidence of lameness during late lactation in dairy cows. DESIGN: Randomized field trial. ANIMALS: 333 Holstein cows. PROCEDURES: Cows without apparent lameness were randomly allocated into 1 of 2 groups approximately 204 days after calving. Cows allocated to the treatment group (n = 161) were examined on a tilt table for diagnosis and underwent hoof-trimming procedures, if needed, for treatment of hoof disorders or lesions. Cows in the control group (n = 172) were not examined. Cows were assigned a locomotion score weekly for 28 weeks after allocation to a group. The number of cows classified as lame during late lactation (approx 205 to 400 days after calving) was compared between groups to assess the efficacy of prophylactic examination and trimming. RESULTS: Incidence of lameness during late lactation was 24% in cows in the control group and 18% in cows in the treatment group. CONCLUSIONS AND CLINICAL RELEVANCE: The 25% decrease in number of new cases of lameness in cows undergoing prophylactic hoof health examination and trimming during midlactation may be relevant for the well-being of dairy cows and should not represent a major economic burden to producers.  相似文献   

Bioavailability of vitamin A sources for cattle     

Alosilla CE  McDowell LR  Wilkinson NS  Staples CR  Thatcher WW  Martin FG  Blair M 《Journal of animal science》2007,85(5):1235-1238

An experiment was conducted to evaluate the bioavailability of 5 sources of vitamin A. It was hypothesized that some vitamin A products have protective coatings that are more resistant than others to rumen destruction and that such protection would result in greater tissue concentrations of vitamin A. Fifty-three yearling Angus x Brahman cattle, consisting of 39 steers and 14 heifers, were stratified by BW and sex and randomly assigned to 6 high-concentrate diet groups receiving no vitamin A supplementation (control) or vitamin A supplemented from the following sources: Microvit A (Adisseo, Acworth, GA), Rovamix A (DSM, Parsippany, NJ), Sunvit A, Lutavit A, and Microvit A DLC (Adisseo). The vitamin A treatment groups were fed daily 80,000 IU of retinol/animal in a low-retinol concentrate diet (78.5% oats, 10% cottonseed hulls, 8% molasses, and 2% cottonseed meal; DM basis) and a free-choice, poor quality (low carotene) hay for 84 d. Every 28 d, BW was determined and liver biopsies and plasma were collected and analyzed for retinol concentrations. All retinol treatments showed significant increases in liver retinol concentrations compared with control animals (P < 0.0001), which steadily decreased over time. At all collection times, Microvit A led to numerically, but not significantly, greater concentrations of retinol in liver than did all other treatments. However, at the end of the experiment, there was no significant difference in liver retinol concentration among Microvit A, Rovamix A, Lutavit A, and Microvit A DLC diets. When liver retinol concentrations at all collection times were considered, Microvit A and Rovamix A appeared to provide the most bioavailable vitamin A.  相似文献   

A PROGRAM FOR AGRICULTURAL DEVELOPMENT     

Thatcher RW 《Science (New York, N.Y.)》1924,59(1520):149-153

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Carbon-nitrogen cycling through microbial formamide metabolism     

Thatcher RC  Weaver TL 《Science (New York, N.Y.)》1976,192(4245):1234-1235

A microbially mediated carbon-nitrogen cycle involving a newly isolated facultatively methylotrophic pseudomonad is described. The new isolate utilizes formamide as its sole carbon, nitrogen, and energy source. Other organisms involved in the proposed cycle are cyanogenic plants; phytopathogenic fungi, which convert cyanogenic glycosides to formamide; and nitrifying microorganisms. This cycle may be quantitatively important in view of the large variety of cyanogenic plants known to exist.  相似文献   

Repletion of blood selenium concentrations in weaned beef calves     

D E Eversole  C D Thatcher  D J Blodgett  J B Meldrum  H D Kent 《The Cornell veterinarian》1988,78(1):75-87

Eighty-three weaned beef calves severely deficient (less than 20 micrograms/L) in blood selenium (Se) were allotted by sex, weight and breed to one of six regimens of Se supplementation for 108 days to examine the efficacy of various Se supplementation programs and to monitor the repletion rate of blood Se concentrations. Cattle in treatment 1 received an IM injection of sodium selenite and an ad libitum feeding of 20 mg Se/kg salt-mineral mixture. Salt-mineral mixtures (treatments 2, 3, 4 and 5) were formulated to contain 20, 40, 80 and 160 mg Se/kg supplement, respectively, and were offered free-choice. Treatment 2 served as the selenium-treated control because 20 mg Se/kg supplement was the maximum permissible by FDA in commercial salt-mineral preparations at the time of this study. Cattle in treatment 6 received a salt-mineral supplement which contained no Se but dried brewers grain (434 micrograms Se/kg) was incorporated in the ration as an organic source of Se and fed at a rate of 1.1 kg/head/day. There was a within group time/treatment interaction (P less than 0.01) among all treatments as blood Se concentrations significantly increased over time. Final mean whole blood Se concentrations for treatments 1-6 were 87.8, 60.6, 95.1, 123.1, 154.2 and 91.4 micrograms/L, respectively. Treatments 1, 3, 4, 5 and 6 effectively increased and maintained whole blood Se concentrations at adequate levels (greater than 70 micrograms/L) by day 84. Treatment 2 (control) increased blood Se during the 108-day study, but blood Se concentrations never exceeded marginal levels (50-70 micrograms/L). Cattle consumed less salt-mineral supplement as the concentration of Na selenite increased from 20 to 160 mg Se/kg supplement.  相似文献