Location: Range and Livestock ResearchTitle: Nanopurification of semen improves AI pregnancy rates in beef cattle) Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/16/2014
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Reproductive efficiency is several times more important than any other factor affecting economic efficiency in beef production. Multiple studies have been conducted to improve fertility of beef cows, but few studies have been conducted to improve fertility in sires. Also, with current improvements to induce estrous cycles and a fertile ovulation in beef females at the onset of breeding, a limiting factor affecting pregnancy rates with artificial insemination appears to be semen fertility. Recent studies have identified biological markers on spermatozoa that are indicative of increased fertility. Ubiquitin is a protein that adheres to the cell surface of defective spermatozoa. Other sperm cell surface proteins present on defective spermatozoa include ligands of lectins. Peanut agglutinin (PNA) is a lectin that binds exclusively to defective sperm acrosomes. Nanoparticles are ultrafine particles of 1 – 100 nm that have been used extensively in immunological diagnostics. Nanoparticles coated with ubiquitin antibodies or PNA have been utilized to visualize defective spermatozoa using fluorescence microscopy. Our hypothesis was that magnetic immunoprecipitation of ubiquitinated spermatozoa by anti-ubiquitin and PNA-conjugated nanoparticles might provide a simple and useful method to improve fertility of semen packaged for AI. Thus, the objective of this study was to determine whether anti-ubiquitin or PNA-conjugated magnetic nanoparticles could be used to efficiently separate defective spermatozoa from fresh ejaculates and increase conceptions rates using AI. Two ejaculates were pooled from each of 4 sires at a commercial AI stud and each pool was divided and subjected to the following purification treatments before packaging at 10 (10M) or 20 million (20M) spermatozoa per straw: Untreated control (10M CON, 20M CON), ubiquitin (10M UBI), and PNA (10M PNA). Crossbred beef cows (n = 798) were artificially inseminated with one of the 4 semen treatments during a 2-year study. Pregnancy was determined by transrectal ultrasonography at approximately d 35 and 90 after AI. Conception rates were affected by semen treatment (P < 0.01) and were 66%, 56%, 65% and 52% for cows inseminated with 20M CON, 10M CON, 10M PNA, and 10M UBI treated semen, respectively. Conception rates of cows did not differ (P = 0.90) between 20M CON and 10M PNA but were greater (P = 0.03) for 20M CON than 10 M CON and tended (P = 0.06) to be greater for 10M PNA than 10M CON semen treatments. Conception rates of cows inseminated with 20M CON and 10M PNA semen treatments were both greater (P = 0.01) than 10M UBI semen treatment. Conception rates of cows did not differ (P = 0.36) between 10M CON and 10M UBI semen treatments. In summary, purification of defective spermatozoa using PNA-conjugated, magnetic nanoparticles increased conception rates following AI.