Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Master of Science / Animal Sciences and Industry / Jeffrey S. Stevenson / Using an activity monitoring system (AMS) equipped with an accelerometer, 2 experiments were conducted to test the hypotheses that: (1) altering progesterone before inducing luteolysis or (2) exposing cows to estradiol cypionate (ECP) or testosterone propionate (TP) after luteolysis would increase occurrence and intensity of estrus. In experiment 1, cows (n = 154) were fitted with an AMS collar and a pressure-sensitive, rump-mounted device (HW) and assigned to 3 treatments: 1) CL only; 2) no CL + progesterone insert (CIDR); or 3) CL + 2 CIDR to achieve different concentrations of progesterone. Progesterone concentration 24 through 120 h post-treatment was greatest (P < 0.01) in CL + 2 CIDR, followed by CL, and no CL + CIDR cows. Estrus occurred 11 to 12 h earlier (P < 0.01) in no CL + CIDR compared with CL-bearing cows. Estrus intensity was greater (P < 0.05) after CL + 2 CIDR than CL only cows. The AMS and HW determined 68 and 62% of qualifying cows to be in estrus (estrus was defined: follicle ≥ 10 mm at PGF[subscript 2α] and progesterone ≤ 0.5 ng/mL 72 h later), respectively. In experiment 2, cows (n = 203) were equipped with an AMS and a friction-activated, rump-mounted patch (Estrotect patch; ET) and assigned to receive 1 mg ECP, 2 mg TP, or control 24 h after PGF[subscript 2α]. Estradiol 24 h post treatment was greater (P < 0.01) in ECP compared with controls. Estrus expression detected by ET in all cows tended (P = 0.10) to be greater for ECP compared with controls. More (P < 0.05) qualifying cows were detected in estrus after ECP compared with controls. Compared with controls and in response to ECP, estrus occurred 17 to 20 h earlier (P < 0.01) and was of greater (P < 0.05) intensity. The AMS and ET determined 71 and 74% of cows to be in estrus, respectively. Of cows exposed to the AMS, HW, or ET, 62 to 74% were detected in estrus and more than 94% subsequently ovulated. In contrast, of the residual cows not detected in estrus, 60 to 76% ovulated in the absence of detected estrus. Only ECP was successful in inducing more estrus expression and, proportions detected in estrus never exceeded 80%. Given the large proportion of cows ovulating in the absence of estrus, further research is warranted to determine if conception is achievable by inseminating cows not detected in estrus by 80 h post-PGF[subscript 2α].

The mare is in our geographic region a seasoned polyestrial animal. Due to human care, some mares can also suppress seasonality. Many factors, both internal and external, are responsible for folliculogenesis, or the development of ovarian follicles. Folliculogenesis is hormonal controlled. It is significantly influenced by the photoperiod, which, by its prolongation, stimulates the production of the relevant hormones. Both can be influenced by both. However, there are other factors that influence this process. This work was mainly focused on the influence of temperament, environment, length of oestrus processes, previous pregnancy, age and stress. In this work, it was found that, for example, in the case of cold-blooded mares, the size of the ovulatory follicle was greater than that of the thoroughbred mares, or that in younger mares the average size of the ovulatory follicle was greater than in the oldest group.

No description available.

The detection of estrus continues to be a primary factor contributing to poor reproductive performance in modern dairy cattle. The objectives of this research were 1) to evaluate performance of automated detection of estrus using a reference standard of ovulation detection with temporal progesterone patterns 2) to evaluate the efficacy of parameters measured by automated detection of estrus systems 3) to evaluate the efficacy of alerts generated by several commercially available systems used for automated detection of estrus and 4) to determine the differences in these parameters among cows with or without poor health conditions at the time of estrus. Systems used for automated detection of estrus can perform better than the previous original reference standard, visual observation for standing behaviors. All systems used for automated detection of estrus tested were similar for estrus detection efficiency.

Call number: LD2668 .T4 1960 P34

Call number: LD2668 .T4 1964 E21 / Master of Science

Call number: LD2668 .T4 1978 W37 / Master of Science

A homogeneous group of thirty-one crossbred ewes was used to determine the effect of administering a progesterone Controlled Intravaginal Drug Releasing Device (CIDR) on circulating levels of progesterone in the subsequent cycle following CIDR removal. Circulating progesterone levels were determined for each ewe through daily blood collection via jugular venipuncture. Each ewe underwent a pretreatment 25 day sampling period (Period 1), a 12 day treatment period characterized by the presence of the CIDR (Period 2), and another 25 day sampling period following CIDR removal (Period 3). During the initial period of the study, progesterone levels in peripheral circulation changed (P < 0.0001, effect of day) in accordance with stage of the estrous cycle and were elevated during the luteal phase. In the second period of the study, progesterone levels were elevated (P < 0.0001) in ewes due to exogenous progesterone from the CIDR device (Period 1 versus Period 2: 1.3 ± 0.1 ng/ml versus 2.4 ± 0.1 ng/ml, respectively). After withdrawal of the CIDR in the third period of the study, circulating progesterone levels were not (P > 0.10) different from those observed in the initial period of the study (Period 1 versus Period 3: 1.3 ± 0.1 ng/ml versus 1.4 ± 0.1 ng/ml, respectively). Data collected in this study revealed that treatment with exogenous progesterone via CIDR for a 12- day treatment period does not influence circulating levels of progesterone in subsequent estrous cycles.

Title from PDF of title page (University of Missouri--Columbia, viewed on March 10, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. David J. Patterson. Includes bibliographical references.