Application of liquid semen technology improves conception rate of sex-sorted semen in lactating dairy cows

Abstract

The objective was to compare reproductive performance of liquid sex-sorted (SS) semen with that of conventional (CON) semen in lactating dairy cows. Between 2011 and 2013, commercial dairy herds (n = 101, 203, and 253 for 2011, 2012, and 2013, respectively) with predominantly Holstein-Friesian cows were enrolled in a contract mating program to produce surplus heifers for export using liquid SS semen. During the spring mating period, each herd was allocated with liquid SS semen at 50% of its daily requirement and the remaining daily requirement was allocated with CON liquid semen. Sperm for producing SS semen was sorted by Sexing Technologies NZ Ltd. (Hamilton, New Zealand) and then packaged using the liquid semen technology of LIC (Hamilton, New Zealand) at a dose of 1 × 10(6) sperm. Artificial insemination (AI) with liquid SS semen was carried out between 43 and 46 h after collection. Conventional semen straws contained 1.25 × 10(6), 1.75 × 10(6), or 2 × 10(6) sperm for semen to be used on d 1, 2, or 3 after collection, respectively. Only CON inseminations on the same days as when SS semen was used were included in the comparison. Herd managers biased usage of SS semen toward cows with a longer postpartum interval before the mating start date (64.0 vs. 62.8 d), cows of higher genetic merit (NZ$107.0 vs. NZ$98.4), younger cows (5.1 vs. 5.2 yr), and cows in which they had more confidence of being genuinely in estrus as measured by a lower percentage of short returns between 1 and 17 d (5.3 vs. 7.5%). After adjusting for these factors, the estimated difference in nonreturn rate between AI with SS and CON semen over the 3 seasons was -3.8 percentage points (SS = 70.2% vs. CON = 74.0%; SS/CON = 94.9%). The estimated maximum difference in calving rate per AI between SS and CON semen was -3.1 percentage points for 2011 (SS = 51.2% vs. CON = 54.3%; SS/CON = 94.3%) and -3.0 percentage points for 2012 (SS = 49.7% vs. CON = 52.6%; SS/CON = 94.5%). Calving data for 2013 were not yet available. The percentage of heifer calves born to AI with SS semen was 87.0% for 2011 and 85.8% for 2012, both of which were lower than the expectation of 90% mainly due to misidentification of calf dams in seasonal dairy herds calving on pasture. In summary, results in this report showed that liquid SS semen only required half the dose rate of frozen SS semen to achieve a reproductive performance of over 94% of CON semen in lactating dairy cows. Careful planning and a robust distribution network are required to avoid semen wastage and to maximize the benefit of liquid SS semen.

Fertility of fresh and frozen sex-sorted semen in dairy cows and heifers in seasonal-calving pasture-based herds

“…Using representative straws generated for the current study, Holden et al (2017) reported abnormally high levels of sperm agglutination (>20%) in both fresh SS treatments (SS-1M and SS-2M), which was associated with lower progressive motility. These high levels of agglutination could affect sperm transport to the site of fertilization, and they could have contributed to the somewhat lower reproductive performance achieved by the fresh SS treatments in the current study compared with Xu (2014).…”

“…One significant weakness in most previously published studies on SS is the fact that treatments were applied to different ejaculates. Indeed, in some studies, different bulls were used for the SS and conventional treatments (Chebel et al, 2010;Xu, 2014); in others, different ejaculates from the same bull were used (De-Jarnette et al, 2009Norman et al, 2010). A recent trial in Germany (Lenz et al, 2016) aliquotted the ejaculate for the different SS treatments (n = 4), but used different contemporaneous ejaculates for the Figure 3.…”

“…A limited number of studies have been carried out with fresh SS. One study in New Zealand (Xu, 2014) reported average nonreturn rates over 3 seasons (2011, 2012, and 2013) that were 94.6% of those achieved with conventional semen at 24 d after AI in dairy cows inseminated with fresh SS (1.25-2 × 10 6 sperm per straw). Nevertheless, fresh SS is currently a niche product.…”

Sperm sexing technology - new directions in medicine

“…The application of this technique in animals also raises great interest, both from scientific as well as economic point of view (9). Thus, the acceleration of reproduction management, the optimization of the biological and economic output at farm level and the improvement of genetic background are just some of the advantages that this technology could provide for live-stock -cattle - (10), swine - (11,12), sheep and goat farms (13).…”

“…Thus, the spread of artificial insemination with sexed semen brings about great advantages for both farm categories (10). It is estimated that by using these technologies, bovine meat production can reach a point where it can compete with chicken meat, both in terms of its nutritional qualities and its low production costs.…”