Laparoscopic insemination technique with low numbers of spermatozoa in superovulated prepuberal gilts for biotechnological application

Abstract

New biotechnologies, such as sperm-mediated gene transfer (SMGT), spermatozoa freezing and spermatozoa sorting have improved the possibilities to produce animals with desirable features. The main problem associated with these technologies is the scarce availability of spermatozoa for insemination. The objective of this study was to develop a laparoscopic insemination (LI) technique in gilt that allows the use of low semen doses resulting in high fertilization rates (FR) and minimal distress to the animal; the efficiency of this technique was compared to conventional artificial insemination (AI). Ten gilts were inseminated 36 h post hCG treatment near both utero-tubal junctions (UTJ) with 1.5 × 10 9spermatozoa/5 mL per horn and 10 gilts (C) underwent conventional AI. Embryos were collected either at two to four cell stage (LI, n = 5; C, n = 5) for determination of fertilization rate or at day 6 for evaluation of developmental competence (LI, n = 5; C, n = 5). LI gilts showed a slightly higher FR than control animals. In a second trial, 24 gilts underwent LI with varying doses (1.5 × 10 8, 1.5 × 10 7, 1 × 10 7, 5 × 10 6 or 1 × 10 6) of semen. Two to four stage embryos were collected and FR was evaluated in each tube. FR obtained with the lowest dose was significantly different from that with other dosages ( P < 0.05). Embryos were cultured in vitro to blastocyst stages (percentage of blastocysts: 79.2 ± 3.6%). In a third trial, five gilts were inseminated with semen processed by SMGT technique; both FR (86.1 ± 9.9%) and transgene protein expression were satisfactory. In conclusion, this study shows that LI can be a useful tool for reducing doses of insemination, without affecting the efficiency of fertilization; this technique could have a wide range of biotechnological applications.