Cattle breed as a source of variation in embryo transfer

The records of 1596 embryo collections were retrospectively analysed to investigate the influence of breed on embryo production and pregnancy rates. The breed of the donor cow was a significant source of variation in the results of embryo transfer. Total embryo production per collection ranged between breeds from 6.0 to 16.2, number of transferable embryos from 2.8 to 6.6 and percent transferable from 37% to 68%. The percent of pregnancies per collection ranged from 2.0 to 4.0 and pregnancy rates from 37% to 75%. The percent of transferable embryos and the pregnancy rate was independent of the total embryos collected. Care should be taken when interpreting the breed differences, since the donor cows were not randomly representative of the breeds and were selected on different bases. Brangus (16.2), Simbrah (15.8) and Beefmaster (13.0) produced the most embryos. The most transferable embryos were collected from Simmentals (6.6), Brangus (6.6), Chianina (6.2), Beefmaster (6.1), Simbrah (6.1) and Saler (6.0) cows. Angus (68%) had the highest percent transferable, followed by Saler (64%), Chianina (60%), Limousin (52%) and Simmental (51%). Pregnancy rates were highest in the Herefords (75%), Saler (57%), Zebu (56%), Charolais (53%), Longhorns (52%) and Simbrah (50%). Estrus response to superovulation varied between breeds, but this did not account for all the breed differences in embryo production.     

Superovulation and embryo recovery from peripubertal Holstein heifers

The use of peripubertal donors in embryo transfer (ET) programs presents significant opportunity to accelerate genetic gain in domestic livestock by reducing the generation interval. These studies were designed to evaluate feasibility of superovulation and embryo recovery in peripubertal heifers (starting at 7.8 months of age), and to determine whether subsequent reproductive and lactational performance of donor heifers were impaired. Study 1 utilized 10 pairs of contemporary full-sibling heifers in which one heifer in each pair was assigned to receive a superovulation regimen and her full-sibling contemporary received placebo. Treated heifers were artificially inseminated at estrus and embryos were flushed transcervically 4-6 days later. Based on recovery of oocytes and/or embryos, 9 of 10 heifers responded to the hormonal regimen and 12 total embryos were recovered. Seven embryos (58%) were transferred into recipients resulting in five pregnancies. Control and treated heifers remained in the herd and were bred at a natural estrus by AI at 15 months of age. Lactation records, i.e., 305 days mature equivalent (305 d ME) were obtained, and all animals were evaluated for udder conformation traits between 32 and 38 months of age. Reproductive traits (age at first calving and days to conception) and lactational traits of heifers subjected to embryo transfer and their non-treated full-siblings did not differ (P > 0.05). Study 2 was conducted to establish the commercial feasibility of hormonally programming peripubertal heifers ranging in age from 7.8 to 9.9; 10 to 11.9; 12 to 13.9 and >/= 14 months. In total, 3982 embryos were recovered from 520 heifers, with 2419 (60.7%) of those categorized as viable (transferable). The number of ova/embryos obtained per flush (5.6 +/- 1.0) and the number of transferable embryos (2.8 +/- 0.5) was reduced (P < 0.05) in heifers of age 7.8-9.9 months compared to all other age groups. There was no difference (P > 0.05) in the number of ova/embryos recovered (7.8 +/- 0.3), or the number of transferable embryos (4.8 +/- 0.2), among heifers that were >/=10 months of age. The number of unfertilized ova did not differ by age, however, more degenerate embryos tended to be recovered from heifers <10 months of age compared to heifers >/=14 months of age. These data indicate that transferable embryos can be safely recovered from heifers beginning at 10 months of age without compromising subsequent reproductive or lactational performance of the donor.     

Influence of inbreeding on reproductive performance, ejaculate quality and testicular volume in the dog

The influence of fast freezing and thawing on bovine embryos at different stages of development was investigated. A total of 20 day-7 embryos and 37 day-8 embryos were thawed and classified morphologically before being transferred nonsurgically to synchronized recipients. Ninety percent (18 20 ) of the day 7 embryos (late morulae and blastocysts) were classified as transferable and a pregnancy rate of 52.9% (9 17 ) was obtained with these embryos. Seventy eight percent (29 37 ) of the day 8 embryos (expanded blastocysts) were classified as transferable, but only 24.1% (7 29 ) of these embryos resulted in pregnancy. The best pregnancy rate was obtained with the blastocysts of day 7 (5 8 or 62.5%), which compares favorably with that of freshly collected embryos. It is suggested that the low pregnancy rate found in the day 8 embryos is related to ultrastructural damages of the desmosomes and tonofilaments within the trophoblast layer, which results in a disturbance of the normal hatching process.     

The day of the estrous cycle that FSH is started and superovulation in cattle

A total of 993 commercial donor cows were superovulated with 28 mg FSH-P. The first injection of FSH-P was administered on one of days 9 through 13 of the donor's estrous cycle. The day that FSH was started did not affect total embryos collected, the number of transferable embryos or the percent transferable. These results did not support the current hypothesis that because the population of antral and preantral follicles in the ovaries on days 9 and 10 is higher, best embryo production should be achieved by starting donor cows on day 9 or 10 of the estrous cycle.     

Recovery rates and embryo quality following dominant follicle ablation in superovulated cattle

To determine the association between dominant follicle ablation and the outcome of a superovulatory regimen, two data sets were constructed from records of 171 recoveries from non-ablated cows and 1214 recoveries from cows that underwent follicular ablation prior to FSH treatment. Data set 1 included all cows with 2 or more records (n = 1385). Data set 2 included paired data for 87 cows which had at least 2 records of both ablated and non-ablated superovulatory attempts. Dominant follicle ablation was performed by use of transvaginal, ultrasound guided aspiration 48 hr prior to the start of FSH. The same FSH protocols were used for both ablated and non-ablated cows. For all cows (data set 1), more total ova/embryos were recovered from the ablation group (12.1+/-0.3 vs 10.5+/-0.8; P=0.06). This difference could be accounted for by greater numbers of non-transferable embryos in the ablation group (6.5+/-0.2 vs 5.3+/-0.6; P>0.01). For the paired data (data set 2), greater numbers of total ova/embryos recovered from the ablation group (12.8+/-1.0 vs 9.7+/-0.7; P=0.01) could also be accounted for by higher numbers of nontransferable embryos in this group (7.8+/-0.8 vs 4.5+/-0.4; P>0.01). There were no differences between groups for high quality embryos, percent cows producing no ova/embryos or percent cows producing no transferable embryos. These data support the premise that synchronization of follicular waves following dominant follicle ablation increases total ova/embryo output. However, the additional embryos were primarily nontransferable thereby negating potential economic gains.     

Preliminary studies on bovine embryo survival following short-term storage at 4 degrees C

A total of 113 non-surgically collected bovine embryos, 5-8 days of age, were stored for 48 hours at 4 degrees C in a modified phosphate-buffered saline solution (PBS). Following storage, embryos were cultured for 8-12 hours at 37 degrees C, and those which were morphologically normal were transferred to synchronized recipients by several methods designed to achieve twin pregnancies. Embryos which were collected and transferred on the same day served as controls. Of 113 embryos stored, 47 (42%) appeared to be transferable after the brief culture period. There was a marked breed effect on viability after refrigeration, with Hereford embryos surviving significantly better than Angus embryos (71% vs. 12%, respectively, p < .001). Post-transfer embryo survival of stored and control embryos, based on actual calvings, was 34 and 48 percent, respectively, a difference which was not significant (p=0.3). A marked difference in pregnancy rate following non-surgical transfer by 2 different technicians was noted (50% vs. 21.7%, respectively).     

A comparison of cloprostenol and dinoprost tromethamine for the control of estrus in bovine embryo transfer

Cloprostenol (500 ug) and dinoprost tromethamine (65 mg in three doses) were similarly effective in controlling estrus during superovulation with FSH-P. Estrous response was 97.3% and 99.5%, respectively. Embryo production was the same measured in terms of the number transferable, total, percent transferable and number of ova cleaved. The percent cleaved was higher in the dinoprost group (75.5%) than the cloprostenol group (67.4%, P=0.019). The number (P=0.04) and proportions (P=0.009) of degenerate embryos were higher in the dinoprost group as compared to the cloprostenol group (2.9 and 27.9% vs 2.2 and 20.5%).     

Use of porcine follicle stimulating hormone after chromatographic purification in superovulation of cattle

Luteinizing hormone was removed from a commercial follicle stimulating hormone preparation (FSH-P) by QAE-A50 column chromatography. Dose rate of the FSH-rich fraction (FSH-W) significantly affected the number of transferable embryos recovered (P = 0.003), increasing from 4.5 ± 3.5 (x ± S.D.) at 2.7 units to 7.0 ± 6.5 at 5.4 units and then declining to 3.1 ± 3.9 at 10.8 units. These differences were the result of changes in the number of embryos fertilized (P = 0.004) (5.9 ± 4.4, 10.1 ± 9.1, and 5.1 ± 5.8 at the three dose rates) and in the total embryos recovered (8.0 ± 6.2, 13.8 ± 14.6, 11.2 ± 8.8). The percent transferable embryos declined with increasing dose of FSH-W from 66 ± 35% to 57 ± 31% and then 27 ± 25% (P < 0.001). In 130 Brahman crossbred cows, 5.4 units of FSH-W produced significantly more transferable embryos (6.3 ± 6.7) than 28-mg equivalents (Armour units) FSH-P (2.9 ± 4.0, P < 0.001). The number of fertilized embryos increased from 5.8 ± 6.7 to 9.0 ± 8.2 (P = 0.019). Adding LH to the FSH-W reversed the advantages of FSH-W. Fertilized embryo production declined from 12.8 ± 8.1 to 5.3 ± 3.6 (P < 0.001), resulting in a decline in the number of transferable embryos from 7.8 ± 6.6 to 4.4 ± 5.0 (P = 0.052). The blood progesterone levels at estrus in cows superovulated with FSH-P were higher (0.88 ng/ml) than in cows superovulated with FSH-W (0.45 ng/ml, P = 0.016). LH had a deleterious effect, due to reduction in fertilization rates on the number of transferable embryos recovered from donor cows stimulated with FSH.     

Embryo production in superovulated cows: Transferable embryos correlated with total embryos

Embryo production was studied in 1,263 donor cows. The number of transferable (good) embryos per collection was highly correlated with the total embryos and ova in a collection (r = 0.64). Total ova and embryos per collection averaged 10.1 with a range from 0-70; the number of good embryos averaged 4.5 with a range from 0-37. Of all collections, 15.3% failed to yield any embryos or ova, and 32.4% did not yield any good embryos. The percentage of good embryos averaged 46.1 while the ratio of good embryos produced (5,680) to total embryos and ova produced (12,699) was 0.45.     

A morphometric study of the external ear: age- and sex-related differences

The human ear is a defining feature of the face. Its subtle structures convey signs of age and sex that are unmistakable yet not easily defined. With analysis of normative cross-sectional data, this study explored anatomic and aesthetic differences in the ear between men and women, as well as changes in ear morphology with age. A total of 123 volunteers were randomly selected for this study. The cohort consisted of 89 women ages 19 to 65 years (median age, 42 years) and 34 men ages 18 to 61 years (median age, 35 years). The average total ear height across the entire cohort for both left and right ears was 6.30 cm, average lobular height was 1.88 cm, and average lobular width was 1.96 cm. As expected based on head size, significant sex-related differences were noted in the distance from the lateral palpebral commissure to both the helical root and insertion of the lobule. Measured distances in both vectors were approximately 4.6 percent longer in men than in women. Similarly, the height of the pinna was significantly larger in men than in women by approximately 6.5 percent. The average height and width of the lobule, however, were nearly identical in men and women. Analysis of age-related data showed a significant difference in the total ear height between the subpopulations; however, this difference was not significant after the lobular height was subtracted from total ear height, suggesting that the lobule was the only ear structure that changed significantly with age. In addition, lobular width decreased significantly with age. This study establishes normative data for ear morphology and clearly demonstrates the changes in earlobe morphology that occur with advancing age.     

Effects of inbreeding on ovarian responses and embryo production from superovulated Mantiqueira breed cows

The objective of the present experiment was to evaluate the effects of different levels of inbreeding on ovarian response and embryo production from superovulated cows. One hundred and thirteen Mantiqueira cows (a medium-size, Bos taurus native dairy cattle breed), with inbreeding coefficients ranging from 0 to 30%, were allocated into five classes of inbreeding and subjected to superovulation treatment. At induced estrus, cows were mated with Mantiqueira bulls (with minimal inbreeding). Six to eight days after mating, the cows were slaughtered, ovarian structures counted and embryos recovered by flushing the uterine horns and oviducts. Sire, season, age, weight, parity and age at first calving of donors did not significantly affect ovarian response or embryo production and quality. There were no effects of inbreeding class on number of total corpora lutea (CL) or number of CL present in the right ovary. However, the number of CL in the left ovary was reduced (P<0.05) in cows with Class 5 (>9%) of inbreeding. The number of transferable, but not the number of non-transferable embryos or the total number of embryos from cows with Class 5 of inbreeding, was lower (P<0.05) than those of cows from Classes 0 to 4 (<9%) of inbreeding. There was a quadratic decrease in the number of transferable embryos as inbreeding coefficient increased (Y=11.077+0.34X-0.0529X(2); R(2)=0.91, P<0.01), but no significant linear or quadratic effect of inbreeding on total number of embryos or number of non-transferable embryos. In conclusion, an inbreeding coefficient>9% reduced the quality of bovine embryos at the initial stage of development.     

Effects of breed, age of donor and dosage of follicle stimulating hormone on the superovulatory response of beef cows

Data were obtained on 1039 recoveries of embryos from beef cows of four breeds at two locations, in clinic and on farm. General linear models procedures were utilized to determine the effects of breed, location, age of donor, dosage of follicle stimulating hormone (FSH) and the interaction of age and FSH on the following dependent variables: 1) the mean number of ova (unfertilized oocytes and embryos) recovered; 2) the mean number and percentage of embryos (fertilized; live and dead) recovered; and 3) the mean number and percentage of transferable embryos recovered. The interaction of age of donor and dosage of FSH with breed and location prevented the pooling of data over breed and location. The mean number of ova recovered was affected by age of the donor (Charolais-in clinic), or the interaction between age of donor and dosage of FSH (Polled Hereford-in clinic and -on farm and Simmental -on farm). The mean number of embryos was affected by age of donor (Polled Hereford-in clinic), dosage of FSH (Simmental-in clinic) or their interaction (Angus-on farm). The mean number of transferable embryos was affected by age of donor (Polled Hereford-in clinic and -on farm, Simmental-in clinic and Angus-on farm). General linear models procedures were utilized to determine the effects of the embryo (stage of development and quality) and the recipient (synchrony with the donor) on the rate of pregnancy. Rate of pregnancy varied with embryo quality score and synchrony of the recipient and the embryo. In conclusion, the superovulatory response was found to be highly breed-specific, and most of the variability in embryos produced was attributed to the number of ova recovered. However, the number of ova, embryos and transferable embryos recovered was further influenced by age of the donor, dosage of FSH or their interaction.     

Dose of FSH-P as a source of variation in embryo production from superovulated cows

Various superovulation treatments were evaluated retrospectively in a commercial embryo transfer program. When it appeared that embryo production was dependent on the dose of FSH-P, a dose response curve to FSH-P was developed and embryo production compared using several treatment regimes. There was a significant effect of dose of FSH-P on embryo production in superovulated cows. At doses in excess of 28 mg, embryo production declined from 5.9 transferable embryos per collection (28 mg) to 2.7 (60 mg). Total embryos collected declined from 14.9 to 6.8 and the percent transferable from 57% to 40%. There was no advantage in using a five-day treatment over a four-day treatment regimen or in using a level over a declining dose regimen. There was a large individual variation in cow response rendering decisions on treatment changes based on single records unreliable. The percentage of zero collections increased with dose rate. Adoption of a 28-mg dose rate in commercial donors resulted in the embryo production forecast by these studies.     

Embryo production from superovulated Holstein-Friesian dairy heifers and cows after insemination with frozen-thawed sex-sorted X spermatozoa or unsorted semen

The aim of this study was to evaluate embryo production in superovulated Holstein-Friesian dairy heifers and cows inseminated with either X-sorted spermatozoa (2 million/dose) or unsorted semen (15 million/dose). Experiment 1 at the research farm involved eight heifers, six cows and semen of one Holstein bull. All transferable embryos were diagnosed for sex. Experiment 2 included embryo collections on commercial dairy farms: X-sorted spermatozoa from three Holstein bulls were used for 59 collections on 28 farms and unsorted semen from 32 Holstein bulls were used for 179 collections on 79 farms. Superovulations were induced by eight declining doses of FSH (total of 12 ml for heifers and 19 ml for cows) starting on days 8-12 of the estrus cycle. Inseminations began 12h after the onset of estrus and were performed two to four times at 9-15 h intervals. Low-dose X-sorted inseminates were deposited into uterine horns and unsorted semen was placed into the uterine body. In Experiment 1, on average 70.3 and 75.0% of embryos recovered from heifers, and 48.4 and 100% of embryos recovered from cows were of transferable quality in X-sorted and unsorted groups, respectively. The proportion of transferable female embryos produced approximately doubled when insemination was with X-sorted spermatozoa compared to insemination with unsorted semen (heifers 96.4% versus 41.1%; cows 81.1% versus 39.8%). In Experiment 2, estimated 53.9 and 65.5% of embryos recovered from heifers, and 21.1 and 64.5% of embryos recovered from cows were of transferable quality in X-sorted and unsorted groups, respectively. Proportions of unfertilized oocytes were 21.1 and 10.6% for heifers and 56.0 and 14.4% for cows in X-sorted and unsorted groups, respectively. Consequently, cows inseminated with X-sorted spermatozoa produced significantly smaller proportions of transferable embryos (p<0.005) and significantly larger proportions of unfertilized oocytes (p<0.001) than those inseminated with unsorted semen. Proportions of quality 1 or degenerated embryos were similar for the two treatments in both heifers and cows. Within treatments, bulls did not significantly affect the proportions of transferable, unfertilized or degenerated oocytes/embryos. It was concluded that using low-dose X-sorted spermatozoa rather than normal-dose unsorted semen for the insemination of superovulated embryo donors can improve the proportion of transferable female embryos produced but this potential may not be achieved in commercial practice, particularly in cows, because of reduced fertilization rates when using low doses of X-sorted spermatozoa.     

Holoprosencephaly in human embryos: epidemiologic studies of 150 cases

One hundred fifty embryos with holoprosencephaly were found among the total of 36,380 conceptuses obtained through induced abortion in the period from 1962 to 1974, giving an overall incidence of 0.4 percent. The occurrence was period from 1962 to 1974, giving an overall incidence of 0.4 percent. The occurrence was largely at random through time, and no "epidemic" was noted in particular years or months, but there appeared more cases derived from conceptions in winter than in summer months. The mean maternal age did not differ significantly from that of the general embryonic population, indicating that, although none of our cases were karyotyped, chromosome aberrations such as trisomies 13 and 18 that are closely associated with maternal age may not constitute a major part as causes of holoprosencephaly in human embryos. Materal age did not differ by the presence or absence of associated external anomalies. No association was found with paternal age, parental consanguinity nor with maternal medical history, including irregularity of menstrual cycles, and smoking and drinking habits. There was an indication that the mothers were prone to have repeated miscarriages, supporting the view that some kind of maternal predisposition is responsible for the causation of holoprosencephaly. Argument was made that, apart from various chromosome aberrations well documented as causes of this malformation, polygenic mechanism probably accounts for the majority of the cases with normal karyotype.     

Superovulation of beef heifers with Folltropin: A new FSH preparation containing reduced LH activity

The optimum superovulatory dose of Folltropin was determined and compared with a standard 28 mg dose of FSH-P in beef heifers. In Experiment 1, mean numbers of corpora lutea (CL) did not differ among the groups treated with 10, 20, 30 or 40 mg Folltropin or FSH-P, and the mean CL number was reduced (P<0.05) only in the 5 mg Folltropin group. Mean numbers of ova/embryos recovered, fertilized and transferable were greater (P<0.05) for the 10, 20 and 30 mg Folltropin groups than for the 5 mg group. The 40 mg Folltropin group and the FSH-P group were intermediate. The percentage of fertilized and transferable embryos did not differ over the dosages used in this experiment. In Experiment 2, mean numbers of CL were greater for the 9, 18 and 36 mg Folltropin groups than for the 4.5 mg group, with the 9 mg group being lower than the 36 mg group (P<0.05). The 18 mg group was intermediate and did not differ. Mean numbers of ova/embryos recovered and fertilized ova were greater for the 9, 18 and 36 mg groups (P<0.05) than for the 4.5 mg group. The percent of fertilized and mean number and percentage of transferable embryos did not differ among treatments. We conclude that Folltropin may be a satisfactory superovulatory replacement for FSH-P and that a dose of 18 to 20 mg Folltropin may be within the optimum superovulatory dosage range for beef heifers. Dosages of Folltropin of more than twice the optimum did not result in deterioration of ova/embryo quality.     

Food Consumption, Feed Efficiency, Metabolic Rate and Utilization of Glucose in Lines of TRIBOLIUM CASTANEUM Selected for 21-Day Pupa Weight

Growth rate, body composition, cell number, cell size, and the activity of four dehydrogenase enzymes were studied from 10 to 25 days of age in one control (1C) and three lines (3, 9, 10) of Tribolium castaneum that had been subjected to long term selection for large 21-day pupae weight.—Selected lines were two- to three-fold larger in size than the control line throughout development. No major differences in percent of protein were detected among the lines but at any particular age, the selected lines were found to have a higher fat content than the control line. The differences in fat content were closely correlated with development such that all the lines reached very similar levels of percent of fat just prior to pupation. Water content showed an inverse relation to percent of fat.—Selection was observed to have caused major changes in the cellular response to growth. The selected lines had an average of from 17% to 48% larger cells (measured as protein/DNA) and were found to have from 37 to 62% more cells (measured as total DNA) than the control line at all ages from 10 to 19 days of age. In addition, the selected lines had a higher RNA content at all ages studied and higher RNA:DNA ratios at the young ages. In contrast the enzyme activities of ICDH and LDH were 60% lower. The results are interpreted as indicating that a more efficient metabolic machinery had evolved in the rapidly growing selected lines.     

Effects of polymorphonuclear neutrophile infiltration into the endometrial environment on embryonic development in superovulated cows

Recent studies on bovine uterine disorders have demonstrated that endometrial infiltration with polymorphonuclear neutrophils (PMN) in the postpartum period or at the time of breeding negatively affects reproductive performance. The objective of the present study was therefore to analyze the effect of endometrial PMN infiltration on superovulation outcome. Cows were synchronized and superovulated receiving a total of three artificial inseminations within 24 h. Endometrial cytologic samples were collected by cytobrush technique at first artificial inseminations (AI) (d −1) and before embryo flush (d 7). Embryos were recovered by uterus flushing at Day 7 and evaluated for total cell number and apoptotic cell index. A total of 425 embryos were flushed out of 48 superovulated cows. The PMN dynamics from first AI to flushing had a significant effect on flushing outcome. Significant differences in terms of number of palpable corpora lutea (14.1 vs 7.2) and transferable embryos (8.8 vs 1.9) were found between cows with PMN proportions increasing from zero (0%) at AI to positive proportions (> 0%) at flushing (group PMNZP) and cows with higher endometrial PMN proportions decreasing to lower but still positive proportions from AI to flushing (group PMNHL). Moreover, cows classified to PMN class zero at first AI flushed a significant higher number of total embryos (10.3 vs 6.9) and transferable embryos (6.8 vs 3.7) compared to cows of PMN class positive at first AI (P > 0.05) in our study. Considering a significant interaction effect between PMN class at first AI and flush (P < 0.05), PMN class at first AI (d −1) correlated significantly with number of total flushed and transferable embryos only in combination with a positive PMN class at flush (d 7). Likewise, PMN class at flush (d 7) beard a significant effect on total number of flushed embryos only when classified to PMN class zero at first AI. Collectively, the present work is the first study that demonstrated a significant relationship between endometrial PMN infiltration at first AI as well as PMN dynamic from first AI to time of flush and superovulation outcome.     

Growth Rate, Body Composition, Cellular Growth and Enzyme Activities in Lines of TRIBOLIUM CASTANEUM Selected for 21-Day Pupa Weight

Growth rate, body composition, cell number, cell size, and the activity of four dehydrogenase enzymes were studied from 10 to 25 days of age in one control (1C) and three lines (3, 9, 10) of Tribolium castaneum that had been subjected to long term selection for large 21-day pupae weight.-Selected lines were two- to three-fold larger in size than the control line throughout development. No major differences in percent of protein were detected among the lines but at any particular age, the selected lines were found to have a higher fat content than the control line. The differences in fat content were closely correlated with development such that all the lines reached very similar levels of percent of fat just prior to pupation. Water content showed an inverse relation to percent of fat.-Selection was observed to have caused major changes in the cellular response to growth. The selected lines had an average of from 17% to 48% larger cells (measured as protein/DNA) and were found to have from 37 to 62% more cells (measured as total DNA) than the control line at all ages from 10 to 19 days of age. In addition, the selected lines had a higher RNA content at all ages studied and higher RNA:DNA ratios at the young ages. In contrast the enzyme activities of ICDH and LDH were 60% lower. The results are interpreted as indicating that a more efficient metabolic machinery had evolved in the rapidly growing selected lines.     

The effects of superovulation of donor sows on ovarian response and embryo development after nonsurgical deep-uterine embryo transfer

This study aimed to evaluate the effectiveness of superovulation protocols in improving the efficiency of embryo donors for porcine nonsurgical deep-uterine (NsDU) embryo transfer (ET) programs. After weaning (24 hours), purebred Duroc sows (2–6 parity) were treated with 1000 IU (n = 27) or 1500 IU (n = 27) of eCG. Only sows with clear signs of estrus 4 to 72 hours after eCG administration were treated with 750 IU hCG at the onset of estrus. Nonhormonally treated postweaning estrus sows (n = 36) were used as a control. Sows were inseminated and subjected to laparotomy on Days 5 to 6 (Day 0 = onset of estrus). Three sows (11.1%) treated with the highest dosage of eCG presented with polycystic ovaries without signs of ovulation. The remaining sows from nonsuperovulated and superovulated groups were all pregnant, with no differences in fertilization rates among groups. The number of CLs and viable embryos was higher (P < 0.05) in the superovulated groups compared with the controls and increased (P < 0.05) with increasing doses of eCG. There were no differences among groups in the number of oocytes and/or degenerated embryos. The number of transferable embryos (morulae and unhatched blastocysts) obtained in pregnant sows was higher (P < 0.05) in the superovulated groups than in the control group. In all groups, there was a significant correlation between the number of CLs and the number of viable and transferable embryos, but the number of CLs and the number of oocytes and/or degenerated embryos were not correlated. A total of 46 NsDU ETs were performed in nonhormonally treated recipient sows, with embryos (30 embryos per transfer) recovered from the 1000-IU eCG, 1500-IU eCG, and control groups. In total, pregnancy and farrowing rates were 75.1% and 73.2%, respectively, with a litter size of 9.4 ± 0.6 piglets born, of which 8.8 ± 0.5 were born alive. There were no differences for any of the reproductive parameters evaluated among groups. In conclusion, our results demonstrated the efficiency of eCG superovulation treatments in decreasing the donor-to-recipient ratio. Compared with nonsuperovulated sows, the number of transferable embryos was increased in superovulated sows without affecting their quality and in vivo capacity to develop to term after transfer. The results from this study also demonstrate the effectiveness of the NsDU ET procedure used, making possible the commercial use of ET technology by the pig industry.