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At least 757 records · Page 42Linked to original sources
PubMed2006

Strategies to improve the fertility of frozen-thawed boar semen for artificial insemination.

Although cryopreservation of boar semen for artificial insemination (AI) was developed 35 years ago, cryopreservation conditions and AI strategies are still considered sub-optimal. AI with excessive numbers of frozen-thawed sperm (5-6 x 10(9) cells), still does not achieve fertility levels similar to AI using liquid semen because of reduced sperm survival. Frozen-thawed (FT) spermatozoa have therefore not been the preferred option for commercial breeding programmes. However, substantial progress has been made regarding boar sperm cryopreservation. Adjustment of cooling and re-warming rates to biophysical properties of boar spermatozoa, new sperm package systems and the achievement of accurately consistent freezing of large numbers of samples using programmable freezers have contributed to post-thaw survival rates above 50%, a threshold similar to that used for bull AI-semen. Moreover, these post-thaw sperm survival rates are consistent within a large population of boars selected for sperm freezability potential, as occurs with AI-bull sires. When such post-thaw boar semen is deposited intra-utero, acceptable fertility (in terms of farrowing rates and litter size) is obtained. Currently, the most effective application of FT-semen for AI is achieved using deep uterine-AI (DUI) which allows placement of a minimal semen dose (in volume 0.5 to 10 mL and sperm number 0.5 to 1 x 10(9) total spermatozoa) into the anterior 1/3 of one uterine horn, with levels of fertility close to AI with liquid semen. However, owing to their shorter life span, FT-boar spermatozoa require an AI-to-ovulation interval not longer than 4-6 h, making peri-ovulatory AI a pre-requisite to obtain the highest possible fertility. Spontaneous ovulation most often occurs when two-thirds of oestrus has passed. Estimation of the duration of oestrus, taking into account the weaning-to-oestrus interval, is helpful when establishing appropriate AI-schedules. However, as the length of oestrus varies within and between farms, different AI strategies should be established a priori. The development of bio-sensors for spontaneous ovulation will widen the use of AI with frozen-thawed frozen semen.

Animals↗
PubMed1991

[A method for the quantification of estrus symptoms in mares].

As part of the veterinary surveillance of horse breeding management, the veterinarian is increasingly often requested to predict ovulation and to give a breeding or insemination advice accordingly. The result of a teasing procedure is indispensable for this advice. A suggestion is made for the quantification of oestrus signs. Oestrus symptoms are classified into four categories. In addition, various factors are mentioned, which affect the result of a teasing procedure.

Animals↗
PubMed1990

[Fertility controls as the measure of herd fertility of dairy stock].

Hormonal analyses have been conducted along with intensive clinical following-up of the animals of three dairy herds in the area of Thessaloniki/Greece for a two year period. The data and progesterone profiles collected by means of milk progesterone assay (EIA) contribute considerably towards confirming and/or correcting clinical diagnoses. The clinical findings and the fertility parameters illustrate the considerable burden of fertility problems present in the dairy herds. The authors assume that faults in nutrition constitute the cause of silent heat and the problems derived from it. Faulty management is mainly associated with difficulties in oestrus diagnoses owing to disorders of fertility, failure to keep precise fertility data and the effects of inconsistent servicing of the cows on the part of the state inseminators.

Animals↗
PubMed1990

Reproductive performance of Friesian cows in Saudi Arabia. II. Resting and service interval, conception rate, and number of services per conception.

A comparative investigation was carried out on criteria for the reproductive performance (n = 590) of 114 imported and 86 locally born Friesian cows reared under semi-arid conditions in Saudi Arabia in 2 farms. No significant differences were found between the two groups as regards the resting time, first service to conception interval, service interval, conception rate, and insemination index. The conception rate was low (46%), and the insemination index-services per conception-was high (2.16). The season had no significant effect on the reproductive performance. Significant differences were found in the conception rate and insemination index of both groups between farms, with lower results for artificial insemination. Heat stress and adaption problems are seen as causing the low conception rate and insemination index. Measures for improving the reproductive performance of Friesian cows in Saudi Arabia are outlined.

Animals↗
PubMed1990

Vaginal probes.

Explore the source record for details and available documents.

Animals↗
PubMed1989

Use of an enzyme immunoassay to determine concentrations of progesterone in caprine plasma and milk.

Concentrations of progesterone (P4) were determined using enzyme immunoassay kits on plasma and milk samples obtained on the same days from 18 lactating dairy goats. Progesterone profiles documenting anestrus, short estrous cycles, normal estrous cycles, a prolonged follicular phase, and prolonged luteal phases were established. When plasma P4 concentrations were used as an accurate indication of the presence or absence of functional luteal tissue, milk P4 concentrations agreed with plasma determinations in 79.4% of the 465 samples tested. Milk samples could not be used to make a definitive decision because of marginal values in 11.2% of the determinations. Milk P4 concentrations were high when plasma P4 concentrations were low in 6.2% of the paired samples, especially those obtained around the time of estrus when peripheral P4 concentrations were changing rapidly. The remaining 3.2% of milk samples had low milk P4 concentrations when plasma P4 concentrations were high. Composite milk from 8 does in estrus or 8 does in the luteal phase was not consistently different from strippings in butterfat percentage or P4 concentration.

Animals↗
PubMed1988

The relationships among palpator experience, milk progesterone concentration and estrus and fertility in cows with palpable corpora lutea treated with cloprostenol.

Two hundred and fifty-one cows fresh at least 37 days with normal reproductive tracts and palpable ovarian structures which clinicians believed to be corpora lutea and which were presumed to be producing progesterone were treated with 500 micrograms of cloprostenol. The cows were stratified into three groups based on milk progesterone concentrations in whole milk samples taken at the time of examination. The low group had milk progesterone concentrations less than or equal to 1 ng/ml, the intermediate group had milk progesterone concentrations between 1 and 3 ng/ml, and the high group had milk progesterone concentrations greater than or equal to 3 ng/ml. The proportion of cows in each group inseminated within 5 days of treatment and the fertility at that breeding were compared. There were no significant differences among the groups with respect to the proportion of cows that came into estrus within 5 days. However, the conception rate of the high group (54%) was significantly greater than that of the intermediate group (26%). To study the relationship between practitioner experience and diagnostic accuracy the proportion of cows with low, intermediate and high concentrations of progesterone selected by clinicians with more than 3 years experience was compared to that for clinicians with 3 years of experience or less. Less experienced clinicians were significantly more likely to make a false positive diagnosis of functional luteal tissue in cows with palpable ovarian structures than were more experienced clinicians.

Animals↗
PubMed1986

[The use of a heat detector in sows].

In the present study a Miyashita heat-detector was tested. It is concluded, that this detector is not suitable for establishing the optimal insemination time.

Animals↗
PubMed1985

The use of milk progesterone and electronic vaginal probes as aids in large dairy herd reproductive management.

In a large herd 427 cows were examined for reproductive condition 26 to 34 days after calving. Progesterone profiles were obtained from a total of over 5000 milk samples which were taken twice weekly for 4 weeks, starting at the time of examination, and again 21, 23, and 25 days later. Researchers lived on the farm during the experiment to sample cows and record all data. Electronic probe measurements of cervical-vaginal mucus also were obtained. All cows were inseminated artificially with frozen semen from one organization. Eleven percent of the cows were not inseminated in the estrual phase as determined by substantial concentrations of progesterone in milk (MP), and 2% were pregnant and aborted following insemination. The MP 23 to 25 days after insemination essentially was 100% accurate in predicting nonpregnancy and was preferable to day 21. When used in conjunction with MP on the day of insemination pregnancy prediction 23 to 25 days after insemination was 84% accurate. Non-return rate 60 days after insemination was 7% higher than palpated pregnancy rate. The use of electronic probes under large herd conditions was labor intensive and did not give repeatably distinctive values at estrus.

Abortion, Veterinary↗