Embryo production in superovulated Angus cows inseminated four times with sexed-sorted or conventional, frozen-thawed semen.

This study tested the hypothesis that four inseminations of commercially frozen sexed semen (>or=2.1x10(6) sperm per 0.25-mL straw) in superstimulated embryo donors would yield a percentage and quantity of transferable embryos similar to that achieved with conventional frozen semen. Bos taurus, angus cows (n=32), stratified by age and body condition, were randomly allocated to receive four inseminations of frozen-thawed semen, either conventional semen (>or=15x10(6) sperm/straw; Conventional) or sexed semen (>or=2.1x10(6) sperm/straw; Sexed) from one of two AI sires. From 10 to 13 d after estrus, follicle-stimulating hormone (FSH) was given twice-daily, with prostaglandin F(2alpha) given twice on the last day. Cows were inseminated once (1x) at first detected estrus and twice (2x) and once (1x) at 12 and 24h later, respectively, with nonsurgical embryo recovery 7 d after first detected estrus. The study was repeated 30 d later (switch-back experimental design). The total number of ova per flush was similar between Conventional and Sexed treatments (10.9+/-1.8 vs. 10.5+/-1.6), but the number of Grade 1 embryos was greater (P<0.01) for Conventional (4.3+/-0.8 vs. 2.3+/-0.7). Conversely, the mean number of unfertilized ova was greater (P<0.05) for Sexed (5.6+/-1.0 vs. 3.0+/-1.2). There was no significant difference between treatments for numbers of degenerate, Grades 2 or 3, and transferable embryos and no significant differences between bulls in percentage of transferable embryos (44.4% and 46.7%). However, fertilization rates and percentage of transferable embryos were affected (P<0.05) by period and donor. In conclusion, superstimulated donor cows inseminated four times had fewer Grade 1 embryos and more unfertilized ova with sexed versus conventional semen.

Larson JE ，Lamb GC ，Funnell BJ ，Bird S ，Martins A ，Rodgers JC ... -  《-》

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.

Peippo J ，Vartia K ，Kananen-Anttila K ，Räty M ，Korhonen K ，Hurme T ，Myllymäki H ，Sairanen A ，Mäki-Tanila A ... -  《-》

Superovulation and embryo transfer in Holstein cattle using sexed sperm.

The use of sexed bull sperm in multiple ovulation and embryo transfer (MOET) programs for Holsteins was evaluated for (1) heifers housed at a commercial embryo transfer (ET) facility (Experiments 1 and 2), and (2) heifers and cows on dairy farms (Experiment 3). In Experiment 1, superstimulated heifers were inseminated with 5 x10(6) sexed (X-sorted; n=5) or unsexed (n=5) frozen-thawed sperm from one bull at 12 and 24h after estrus detection. No difference was observed in the rates of transferable embryos (53.4% vs 68.1%), degenerate embryos (24.8% vs 26.6%) and unfertilized ova (21.8% vs 5.3%) between sexed and unsexed sperm, respectively, except for the percent of female transferable embryos diagnosed by embryo sexing (100% vs 49.3%, P<0.0001). In Experiment 2, donors were inseminated twice with 5 x10(6) sexed unfrozen sperm (n=10) or sexed frozen-thawed sperm (n=9). Embryo production rates for both treatments were similar to that observed on a commercial ET facility using unsexed sperm. Pregnancy rates for frozen-thawed embryos were similar for sexed and unsexed sperm (70.4% vs 72.4%, respectively). In Experiment 3, 99 flushes were conducted using sexed frozen-thawed sperm from nine bulls but an overall statistical analysis was not completed because the use of bulls was not balanced. However, for one bull with balanced usage, the rate of transferable embryos was higher in heifers than in cows (P<0.05) inseminated twice with 5 x10(6) sperm/dose (10 x10(6) total). We concluded that the use of sexed frozen-thawed sperm (> or =90% X-sperm biased and 10 x10(6) total sperm) may be economically viable for commercial MOET programs in Holstein heifers.

Hayakawa H ，Hirai T ，Takimoto A ，Ideta A ，Aoyagi Y ... -  《THERIOGENOLOGY》

Embryo production from superovulated cattle following insemination of sexed sperm.

Two trials were conducted to ascertain fertilization rate, embryo quality and numbers of transferable embryos in superovulated heifers and cows inseminated with sexed sperm. Inseminates contained 2 x 10(6), 10 x 10(6) or 20 x 10(6) total sperm enriched for the X- or Y-chromosome ( approximately 90%) by flow cytometry/cell sorting. Non-sexed inseminates contained 40 x 10(6) total sperm. Donors in each trial were allocated to one of each of the bulls included in that study. Each donor was inseminated with frozen/thawed sperm from the same bull for each treatment in successive courses of superstimulation with twice daily i.m. injections of FSH for 4 d. Heifers and cows were inseminated 12 and 24 h after visually observed standing estrus in Trial 1. In Trial 2, a single timed inseminate was used 70-72 h following PGF(2alpha). Ova/embryos were collected non-surgically 7-7.5 d after insemination. In both trials, fewer ova were fertilized with sexed versus non-sexed treatments and with 2 x 10(6) sexed sperm compared to higher doses (P < 0.05). However, insemination of 20 x 10(6) total sexed sperm of >or=90% purity resulted in similar numbers of transferable embryos of the desired sex compared to that for non-sexed sperm.

Schenk JL ，Suh TK ，Seidel GE Jr 《THERIOGENOLOGY》

Embryo production with sex-sorted semen in superovulated dairy heifers and cows.

The aim of this study was to examine the effect of sex-sorted semen on the number and quality of embryos recovered from superovulated heifers and cows on commercial dairy farm conditions in Finland. The data consist of 1487 commercial embryo collections performed on 633 and 854 animals of Holstein and Finnish Ayrshire breeds, respectively. Superovulation was induced by eight intramuscular injections of follicle-stimulating hormone, at 12-hour intervals over 4 days, involving declining doses beginning on 9 to 12 days after the onset of standing estrus. The donors were inseminated at 9 to 15-hour intervals beginning 12 hours after the onset of estrus with 2 + 2 (+1) doses of sex-sorted frozen-thawed semen (N = 218) into the uterine horns or with 1 + 1 (+1) doses of conventional frozen-thawed semen (N = 1269) into the uterine corpus. Most conventional semen (222 bulls) straws contained 15 million sperm (total number 30-45 million per donor). Sex-sorted semen (61 bulls) straws contained 2 million sperm (total number 8-14 million per donor). Mean number of transferable embryos in recoveries from cows bred with sex-sorted semen was 4.9, which is significantly lower than 9.1 transferable embryos recovered when using conventional semen (P ≤ 0.001). In heifers, no significant difference was detected between mean number of transferable embryos in recoveries using sex-sorted semen and conventional semen (6.1 and 7.2, respectively). The number of unfertilized ova was higher when using sex-sorted semen than when using conventional semen in heifers (P < 0.01) and in cows (P < 0.05), and the number of degenerated embryos in cows (P < 0.01), but not in heifers. It was concluded that the insemination protocol used seemed to be adequate for heifers. In superovulated cows, an optimal protocol for using sex-sorted semen remains to be found.

Kaimio I ，Mikkola M ，Lindeberg H ，Heikkinen J ，Hasler JF ，Taponen J ... -  《-》