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W Hazeleger

Publications and source records attributed to W Hazeleger.

11 recordsLinked to original sources
PubMed2001

Recent developments in pig embryo transfer.

Porcine embryo transfer has been performed for approximately 50 years, and surgical methods have proven to be reliable for collection and transfer of embryos. However, surgical collection and transfer have the disadvantage of being less useful on the farm. Recently, new procedures for both collection and transfer of embryos have been developed to improve usefulness. The surgical procedure has been refined to a minimally invasive procedure, using endoscopy for collection and transfer of embryos. A nonsurgical procedure for embryo collection has also been devised, but is limited to use in sows with surgically shunted (shortened) uterine horns. Nonsurgical embryo transfer procedures have been developed recently and have proven to be successful. The nonsurgical procedures are preferable to surgical procedures from an animal welfare point of view and because these procedures can be performed on farms without the need for special facilities.

Animal Welfare↗
PubMed2000

Periovulatory hormone profiles and components of litter size in gilts with different estrogen receptor (ESR) genotypes.

Estrus, endocrine changes during the periovulatory period, and components of litter size at Day 35/36 of pregnancy were studied in gilts with estrogen receptor genotype AA (AA gilts) or BB (BB gilts), in which the B allele is associated with a larger litter size. Neither estrus length nor estrous cycle length was affected by estrogen receptor genotype. No differences in periovulatory plasma LH, estrogen or progesterone profiles between the AA and BB gilts were detected. Furthermore, temporal aspects of these profiles were not different for both genotypes. Although the B allele is associated with a larger litter size, no differences in number of corpora lutea or number and percentage of vital Day 35/36 embryos were found in this study. This indicates that the difference in litter size is not due to differences in oocyte maturation, fertilization, implantation or embryonic survival, but is likely caused by a difference in fetal survival. Thus, uterine capacity might be different for both genotypes. The available uterine space per embryo seems to be the same for both genotypes, as is endometrial folding of uterine surface area. However, a difference in placental size was found. Embryos of BB gilts had significantly longer placentae than embryos of AA gilts. These results suggest a higher chance for placental insufficiency in AA gilts, leading to the expected higher fetal mortality compared with the BB gilts. The difference in placental size might have been related to a difference in the timing of embryonic mortality.

Animals↗
PubMed2000

Effect of superovulation induction on embryonic development on day 5 and subsequent development and survival after nonsurgical embryo transfer in pigs.

To evaluate the effects of eCG dosage on recovery and quality of Day 5 embryos and on subsequent development and survival after embryo transfer, batches of 5 to 10 donor sows were treated with 1000 or 1500 IU eCG. Recipients from the same batch were synchronously treated with 800 IU eCG. Ovulation was induced with 750 IU hCG (72 h after eCG) in donors and recipients. Donors were inseminated and embryos were collected at 162 h after hCG (120 h after ovulation). Ovulation rate was lower using 1000 IU eCG (28.5+/-11.7; n=48) than 1500 IU eCG (45.7+/-20.3; n=32; P<0.0001). Embryo recovery rate (82.9+/-16.9%) and percentage expanded blastocysts (56.2+/-31.4%) were similar (P>0.05). Expanded blastocysts from each group of sows were pooled into 2 groups within eCG treatment, containing embryos from normally ovulating sows (< or = 25 corpora lutea [CL]) or from superovulated sows (> 25 CL). Average diameter and number of cells of a random sample of the expanded blastocysts per pool were recorded. The average diameter of blastocysts (160.5+/-11.5 microm) was not affected by eCG dosage or ovulation rate (P>0.10). The average number of cells per embryo was higher in the 1000 IU eCG group (84.3+/-15.3) than in the 1500 IU eCG group (70.2+/-1.9; P<0.05) but was similar for normal and superovulated donors within each eCG group (P>0.10). Of the 4 groups, litters of 28 to 30 blastocysts were nonsurgically transferred to 27 synchronous recipients. Pregnant recipients were slaughtered on Day 37 after hCG treatment to evaluate embryonic development and survival. Pregnancy rate for the 1000 and 1500 IU eCG donor groups was 71% (10/14) and 46% (6/13; P>0.10), respectively. The number of implantations and fetuses for the 1000 IU eCG groups was 12.9+/-3.0 and 11.1+/-2.7, and 14.2+/-7.0 and 10.5+/-4.6, respectively, for the 1500 IU eCG groups (P>0.10). After post-priory categorizing the litters of blastocysts to below or above the average diameter (158 microm) of the transferred embryos, irrespective of eCG dosage or ovulation rate, the pregnancy rate was 43% (6/14) and 77% (10/13; P<0.10), respectively. Post-priory categorizing the transferred litters to below or above the average number of cells per embryo litter, irrespective of eCG dosage or ovulation rate, showed no differences in pregnancy rates or number of implantations and fetuses (P>0.10). It was concluded that eCG dosage affects embryonic development at Day 7 after hCG, and this effect was not due to ovulation rate. Embryonic survival after nonsurgical transfer was not related to eCG dosage but tended to be related to the diameter of the blastocysts.

Animals↗
PubMed1999

State of the art in pig embryo transfer.

Embryo transfer in pigs has required surgical procedures in both donors and recipients. Over the last decade, procedures have been developed for transferring embryos by endoscopic or nonsurgical (transcervical) procedures. The feasibility of these procedures for practical application and the latest results of these new approaches are compared here. Factors affecting the current results and obstacles to be overcome in the near future are also discussed. Finally, some relevant embryo collection procedures and applications are briefly summarized.

Animals↗
PubMed1999

Uterine luminal proteins and estrogens in gilts on a normal nutritional plane during the estrous cycle and on a normal or high nutritional plane during early pregnancy.

In gilts, a high plane of nutrition during early pregnancy often results in increased embryo mortality, possibly related to changes in embryo-uterine asynchrony at a critical stage of pregnancy (around Day 11). Therefore, in the present study, uterine luminal proteins and estrogens were studied between Days 5 and 16 after the onset of estrus in gilts on either a normal (2.5 kg/d, cyclic and pregnant gilts) or a high (4.0 kg/d, pregnant gilts only) feeding level. Conceptus recovery rate between Days 5 and 12 was not affected by the feeding level during early pregnancy, neither were systemic progesterone levels. Between Days 9 and 11, dramatic changes took place in the protein composition of the uterine luminal 10kD+ proteins, shifting from most (90%) of the acidic proteins at Day 5 and 7 to approximately 50% at Day 11/12, especially due to an increase in basic proteins with an iso-electrical point of more than 8. This shift occurred most rapidly for the pregnant gilts at the high feeding level and least rapidly in the cyclic gilts, resulting in significant differences in the relative amount of acidic proteins at Day 10 and 11 after the onset of estrus (P < 0.05). Similarly, levels of estrogens in the uterine flushings at Days 10, 11 and 12 were always highest for the pregnant gilts on the high feeding level and were always lowest in the cyclic gilts (P < 0.05); pregnant gilts on the normal feeding level showed intermediate estrogen levels. The fact that gilts on a high feeding level during early pregnancy show more rapid changes in the uterine luminal protein composition and embryonic estrogen production seems to suggest that the rate of these changes may be related to embryo survival.

Animal Nutritional Physiological Phenomena↗
PubMed1997

Vaginal temperature is not related to the time of ovulation in sows.

The relationship between vaginal temperature and ovulation time was studied in sows. The vaginal temperature was measured continuously between Day 4 and Day 10 after Altrenogest-treatment in 10 sows. Oestrus was checked with a vasectomized boar at 8-h intervals, and during oestrus, ovulation time was checked with transrectal ultrasonography at 2-h intervals between 07:00 h and 23:00 h. Two sows ovulated between 23:00 h and 07:00 h, and these sows were taken out of the experiment. In the eight remaining sows, a clear day/night rhythm in vaginal temperature was found: between 03:00 h and 09:00 h, vaginal temperature (LSM +/- sem, corrected for sow) was on average 38.2 +/- 0.01 degrees C; between 15:00 h and 21:00 h, vaginal temperature was on average 38.5 +/- 0.01 degrees C (P < 0.001). Between 4 days before ovulation and 2 days after ovulation, no changes in temperature could be found that were related to ovulation time in any of the sows. Therefore, in sows, changes in vaginal temperature cannot be used as a predictor for ovulation time, and consequently cannot be used to predict the best time for insemination.

Animals↗
PubMed1995

Effects of a second insemination after ovulation on fertilization rate and accessory sperm count in sows.

Insemination immediately after ovulation causes low fertilization results owing to a low fertilization rate and possibly also owing to polyspermic fertilization. The present experiment was undertaken to study the effects of a second insemination after ovulation on fertilization rate and embryonic development. In multiparous crossbred sows, transrectal ultrasonography was used at intervals of 4 h to determine ovulation. All sows (n = 91) were artificially inseminated with 3 x 10(9) mixed spermatozoa and, in 31 sows, a second insemination took place at 3 +/- 1 (mean +/- SD) h after ovulation. At 119 +/- 5 h after ovulation, the percentage of normal embryos and the accessory sperm count were determined. In the sows that were inseminated once, the percentage of normal embryos decreased when insemination took place more than 24 h before ovulation, from 88 +/- 20% (16-24 h; n = 15) to 63 +/- 40% (24-32 h; n = 10) (P < 0.05). In the sows that were inseminated again after ovulation, the percentage of normal embryos was high, irrespective of the period between first insemination and ovulation. The difference in percentage of normal embryos between the sows that were inseminated once or twice was significant when the first insemination took place between 24 and 32 h before ovulation; 63 +/- 40% (inseminated once, n = 10) and 97 +/- 5% (inseminated twice, n = 8) (P < 0.05). The accessory sperm count of the normal embryos in a litter was positively related to the percentage of normal embryos in a litter, and this relation was not affected by the interval between first insemination and ovulation or by the number of inseminations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Detection of the coccoid form of Campylobacter jejuni in chicken products with the use of the polymerase chain reaction.

Detection of the coccoid form of Campylobacter jejuni with the use of the polymerase chain reaction (PCR) was examined. Coccoid cells of this pathogen, formed at different temperatures, showed different detection characteristics in the PCR. For spirals and cocci formed at 4 degrees C and 12 degrees C, the detection limit was about 2 x 10(3) cells/PCR. However, for detection of coccoid cells formed at 25 degrees C and 37 degrees C, at least 2 x 10(4) cells per PCR were needed. PCR was also performed on homogenates in peptone saline solution and enrichment broths of chicken meat and chicken liver that were artificially contaminated with cocci formed at 4 degrees C. PCR-products of these samples could not be demonstrated clearly.

Animals↗
PubMed1992

Morphological indications of secretion by uterine epithelial cells and changes in the ratio between acidic and basic uterine proteins during early pregnancy in Chinese Meishan pig.

In Chinese Meishan pig embryonic mortality appears relatively low compared to European breeds. Most of embryonic loss in pig is believed to take place during early pregnancy. It is of interest to know possible specific features associated with low mortality. Therefore, the ultrastructure of the endometrial epithelium of Meishan pig was studied between Days 4 and 12 of pregnancy, and compared with earlier results on Yorkshire/Dutch Landrace interbreed (Y/DL). Furthermore, total protein and the relative amounts of acidic and basic proteins were determined in the uterine flushings, and compared with earlier results on Dutch Landrace (DL). As holds for European breeds, uterine glandular and luminal epithelium have to be considered as functionally different cell populations. Their morphology differs and suggests the synthesis of different secretory products. The periods of secretion are not the same: the luminal epithelium shows signs of product release during the whole period studied, the glands deliver their secretions from Day 12. This is correlated with a sudden increase in total protein in uterine flushings. Between Days 4 and 12, the relative amount of acidic proteins decreases from 92% to 47% in DL and from 88% to 38% in Meishan, resulting in a shift from acidic protein dominance to a mild dominance of basic proteins in both breeds, but most prominent in Meishan.

Animals↗
PubMed1987

[Health and fertility in relation to production. Embryonal mortality in swine: incidence and possibilities for prevention].

The embryonic mortality rate in the pig is 20-40%. Part of the variation in incidence is due to breed differences. Unavoidable chromosome mutations are unimportant as a cause of embryonic mortality. Within breeds, the incidence depends on factors such as the boar, the interval between parturition and conception, the time of insemination in relation to ovulation, and the level of feeding and stress during early pregnancy. If these factors are taken into consideration, the incidence of embryonic mortality can be reduced. The aetiology of a part of the embryonic mortality is still unknown, and it is thus difficult to predict whether this part can be prevented. In this context, however, recent publications on the relationship between variation in early embryonic development and embryonic mortality, and on the positive effect of the administration of exogenous steroids during early pregnancy on litter size, are promising.

Animals↗