Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"conception rate"”.
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Synchronization of estrus, conception rate, and embryonic mortality in beef cattle following treatment with progesterone-releasing intravaginal devices or melengestrol acetate in conjunction with PGF₂α
… cycle on estrous response (ER), first service conception rates (CR), pregnancy rates (PR), and embryonic mortality (EM) after 25 d of gestation. Angus or Angus crossbred cattle (n=391) at two locations were assigned to receive either melengestrol acetate for 7 d (MGA-PGF; .5 mg/hd/d, n=136) or …
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Simulation of genetic control of reproduction in beef cows
… performance. Parameters for single-service conception rate and days from calving to first service (postpartum interval) were developed from the literature. Estimates of the heritability and repeatability (h², t) of each of these traits in four simulated data sets were RUN1 (.20, .20), RUN2 …
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Comparison of three estrus detection systems during summer heat stress in a large commercial dairy herd
… and interval between onset of estrus and AI on conception rate were determined using linear contrasts and logistic regression. Efficiencies for detection of estrus, determined by comparing detected periods of estrus with a theoretical total of 707 periods, were 45.8% (V), 33.2% (A), 40.3% (HW), …
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Genetic and phenotypic relationships among fifteen measures of reproduction in dairy cattle
… pe.rformance were calculated. These included conception rate, number of services, service period length, days open, age at first breeding, calving interval, days between services, and return to estrus lag. First, second and third service period were each analyzed separately, while fourth and …
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Hormonal, environmental, nutritional and lactational interrelationships with estrous behavior and conception in dairy cattle
… factors which may affect estrous behavior and conception rate. All cattle were observed for estrous activity twice daily between 0800 to 1000 hr (am) and 2000 to 2200 hr (pm). Breedings were made at the first observation of estrus (0 hr) or following the next heat check (12 hr). Animals first …
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Untersuchungen zur verzögerten Ovulation beim Rind
… cattle and to evaluate its influence on the conception rate. The examinations were carried out on 304 animals (293 cows and 11 heifers) of the breeds Swiss Brown (65%), Holstein (26%) and Simmental (9%). The animals were kept on 49 different farms in the area of the Artificial Insemination …
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Postpartum ovarian activity and response to progestagen treatment in rustic beef cows (Spanish Retinta) underfed to simulate their typical ranging conditions
… the experiment. Treatment neither affected the conception rate nor the interval from calving to first estrus or to conception. High-BCS cows had greater conception rate and resumed estrous cyclicity and conceived earlier than low-BCS cows. Cows remaining nonpregnant by weaning had a lower and …
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Reproductive performance of Holstein cows treated with prostaglandin F2a, gonadotropin releasing hormone, and recombinant bovine Somatotropin
… and recombinant bovine somatotropin (rbST) on conception rates following a timed insemination (TAI) protocol in lactating dairy cows. A further objective included the evaluation of the efficacy of the Early Conception Factor (ECF) test kit. Recombinant bST may offer some benefit when used in …
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Methods of Measuring the Fertilizing Ability of Sperm
… precise than the methods commonly used, such as conception rate, non-return rate or litter size. When fertilizing ability is measured by one of these methods females are generally inseminated with sperm of a concentration that results in 90% or more fertilized eggs. Several experiments were …
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Characterization of Phosphatidylserine Expression in Bovine Sperm
… may impact it, as previous research demonstrated that phosphatidylserine (PS) plays a role in murine fertilization. Despite conventionally being an apoptotic marker, it is present on viable and fertilization-competent murine sperm, however, less is known of the possible role of PS in bovine …
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Índices reprodutivos do rebanho de ovinos Morada Nova, da estação experimental bacia escola de São João do Cariri - PB
… the study showed that the reproductive rates have very dependent on the use of zootechnical bookkeeping, it can be seen, the performance rates of weight gain of lambs in the different types of delivery, and to be weaned, so it was perceived that male lambs originating from single birth …
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Reducing Teenage Pregnancy in England, 2010 to 2015: A case study
… across England sustained and improved their conception rate reductions following implementation of the 2000-2010 national Teenage Pregnancy Strategy. Little is known of the factors underpinning these successes in the policy context beyond 2010. This thesis investigates sustained and improved …
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Optimal time of insemination in dairy cattle identified in estrus by HeatWatch
… enough to provide the information needed to accurately time insemination, thus preventing AI from obtaining its full conception rate potential. Herds (n = 17) participated in a trial designed to evaluate percent pregnant relative to various characteristics of estrus. Herds utilized HeatWatch® …
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Evaluation of 72 h Cosynch and 5 or 7 d post-AI gonadotropin releasing hormone on first service pregnancy rate in lactating dairy cows
… were evaluated in samples collected at five separate times and CL volume and number were recorded at 30 d pregnancy examination for Holstein (n = 77) and Jersey (n = 33) cows. GnRH treatment did not affect PR (Control - 47.2%, 5 d GnRH - 40.5%, 7 d GnRH – 44.7%) or P4, but increased TCLV compared …
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Estimation of economic weights for a beef cattle selection index
… maximum daily milk production (PMA) and 60-d conception rate (CP) on costs per 100 kg slaughter weight (COST) and costs per 100 kg weaned weight (WNCOST) both adjusted for cull cow sales. Genetic inputs were defined as peak values for mature cows in an unrestricted environment and ranged from …
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A diversified exploration of beef cattle genetics: miRNA and beef bull fertility in beef and dairy female populations
… to quantitative traits, genetic analysis of sire conception rate (SCR) in dairy cow and beef heifer populations, and the genetic correlation between SCR in both populations. The objectives of the miRNA project were to elucidate differentially expressed (DE) miRNA resulting from changes in …
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Induction of fertile estrus during seasonal anestrus in ewes and fall born ewe lambs
… with time after ram introduction, and the conception rate varied quadratically with the time of observation of onset of estrus. Progesterone treatment increased the percentage of ewes lambing and the number of lambs born per ewe exposed over that observed in ewes introduced to rams alone. …
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Influence of prepartum diet type on cow performance and subsequent calf performance
… with lower BCS (P = 0.05); nevertheless, overall conception rate was not different (P = 0.83). No differences (P ≥ 0.42) in milk production were detected. Weaning BW, final BW, and days on feed were not different (P ≥ 0.19); and as result, no difference (P = 0.68) in feedlot ADG was detected. …
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Strategies to Improve Reproductive Efficiency in Cattle with Dietary Intervention
… days to ovulation postpartum, overall pregnancy rates, and pregnancy at first AI in cattle. Most notably, the highest predicted overall pregnancy rate for multiparous cows was observed at high crude protein (CP), moderate non-structural carbohydrates (NSC), Low neutral detergent fiber (NDF) and …
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An assessment of the biotin needs of developing gilts and reproducing sows in a modern production system
… the number and frequency of various toe lesions. Conception rate and the weaning to estrus interval were improved (P<.05) with SB. No significant responses were noted in farrowing and lactation performance. There was a trend for SB to improve litter size in multiparous females. Feeding SB diets …
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