Comparison between low-dose, high-sort and high-dose, low-sort semen on conception and calf sex ratio in Jersey heifers and cows

Abstract

The objective of this clinical trial was to compare conception and newborn calf sex ratios among Jersey heifers and lactating cows inseminated with either standard sex-sorted semen (low-dose, high-sort; LDHS) containing 2.1 × 10(6) sorted sperm at 90% purity or high-dose, low-sort (HDLS) semen containing 10 × 10(6) sorted sperm at 75% purity. After a specified voluntary waiting period (VWP), female subjects, consisting of nulliparous heifers (VWP 10 mo of age) and lactating cows (VWP 50d in milk), received their first service and were systematically allocated to each treatment group in the order in which they presented for artificial insemination (AI). Females were bred to the same sire and type of sex-sorted semen for up to 2 additional services. Animals that were not pregnant after 3 breeding attempts were excluded. A total of 1,846 services were performed on 1,011 eligible females (LDHS; n=494, HDLS; n=517), which consisted of 516 nulliparous heifers and 495 lactating cows. Study groups were comparable with respect to the mean age at first AI for nulliparous heifers and the mean days in milk at first AI for parous cows. Insemination with HDLS semen did not result in a higher proportion of pregnancies per AI (P/AI) compared with LDHS semen for either nulliparous heifers (P/AI=43 vs. 38%) or parous cows (P/AI=47 vs. 43%). Insemination of nulliparous heifers using HDLS resulted in a lower proportion of newborn female calves compared with those bred to LDHS (76% vs. 87%). Similarly, lactating cows bred to HDLS gave birth to a lower proportion of newborn female calves compared with those bred to LDHS (79 vs. 90%). The odds ratio for a female calf to be born to an animal inseminated with HDLS compared with LDHS was 0.32 for nulliparous heifers and 0.19 for parous cows. Overall, the use of HDLS resulted in fewer females compared with LDHS, which may be explained by the lower concentration of X-bearing spermatozoa in HDLS compared with LDHS.

Effect of insemination site and diameter of the pre‐ovulatory follicle on the odds of pregnancy in heifers using sexed or non‐sexed semen

“…10 The pregnancy per AI of sexed semen is commonly reported to be 70-80% of the pregnancy per AI of non-sexed semen, 11-14 although higher and lower relative pregnancy per AIs have also been reported. 10 The pregnancy per AI of sexed semen is commonly reported to be 70-80% of the pregnancy per AI of non-sexed semen, 11-14 although higher and lower relative pregnancy per AIs have also been reported.…”

“…1,2,[4][5][6][7][8] Sexed semen may also give dairy farmers the opportunity to sell surplus replacement heifers or breed a proportion of cows to beef semen, thus producing more cross-bred beef calves instead of low-value dairy bull calves. 10 The pregnancy per artificial insemination (AI) of sexed semen is typically reported to be 70-80% of the pregnancy per AI of non-sexed semen, [11][12][13][14] although this varies, with higher and lower relative pregnancy per AIs also reported. 9 Despite the benefits of using sexed semen, the higher purchase price and lower fertility associated with the use of sexed semen are costs that can off-set these benefits.…”

“…3,8,15 Sexed semen is more commonly used in heifers (rather than lactating cows) because a lower pregnancy per AI in heifers will not lead to an increase in the average days in milk of the lactating herd, although the average interval from birth to parturition in the heifers will increase. 10 We also hypothesised that heifers with larger pre-ovulatory follicles at insemination may also be more likely to conceive to sexed semen compared with heifers with small pre-ovulatory follicles. 12,13 The objective of this study was to determine whether cornual insemination or the diameter of the pre-ovulatory follicle at the time of AI has an effect on the pregnancy per AI of sexed semen in Holstein heifers.…”

Sex-sorted sperm in farm animals: scale of use, the effectiveness of insemination, risk factors

“…Uzasadniona wydaje się głęboka depozycja nasienia sortowanego do ipsilateralnego rogu (63). Unasienniając jałowice starsze niż 10 miesięcy i krowy jersey (> 50 dni po porodzie) dawką nasienia sortowanego zawierającą 2,1 × 10 6 plemników o wysokim stopniu czystości (90%), względnie dawką zawierającą 10 × 10 6 plemników o niższej czystości (75%) nie stwierdzono istotnych różnic we wskaźniku zacieleń (41). Jak wynika z danych tabeli, pewien wpływ na wyniki zacieleń po inseminacji nasieniem sortowanym wywiera rasa krów (14,22,44).…”

“…Wskaźnik ciąży po inseminacji nasieniem seksowanym buhajów rasy murrah był wyższy niż w przypadku buhajów nili-ravi, 52,5% w porównaniu do 46,1% (40). Istotne różnice notowano w odsetku ciąż po inseminacjach wykonywanych w różnych porach roku oraz przez różnych inseminatorów, natomiast w przeciwieństwie do krów rasy holsztyńsko-fryzyjskiej u mieszańców wskaźnik zacieleń u krów i jałowic był podobny (41).…”