Uticaj sadržaja proteina u spermalnoj plazmi nerasta na parametre razređene sperme i fertilitet veštački osemenjenih krmača / Effect of protein content in the boar seminal plasma on the diluted semen parameters and fertility of artificially inseminated so

Artificial insemination (AI) is the most important reproductive biotechnology in the intensive pig production. Effective selection of high fertile genetically superior boars and high fertility rate in the AI sows has a great economic impact on the efficiency of using these biotechnology in practice. However, previous studies reported that the evaluation of classical seminal parameters (spermatozoa concentration, viability, motility and morphology) are not sufficient indicators of boar fertility and reproductive performance. On the other hand, it has been shown that artificial insemination often result in lower fertility rates than those obtained by natural mated sows, mainly as a result of insemination with overdiluted and/or preservation of liquid AI doses for a longer time (3 to 5 days). The results of previous studies indicate that the components of seminal plasma has a key influence on the spermatozoa fertility in vivo and in vitro, as well as on the physiological processes important for successful fertilization and embryo development in uterus. Therefore, the main objective of the present study was to: (a) determine the content of protein in seminal plasma of the AI boars at the commercial pig farm in Serbia, (b) evaluate the influence of protein content in seminal plasma on sperm motility and morphology in native and diluted semen after storage for 3 days and (c) investigate the influence of transcervical seminal plasma infusion into the uterus, prior the classical AI dose application, on the sows fertility rate. Content of protein was ranged from 1% to 6.5%, as determined in 212 ejaculates taken from 106 AI boars. Low protein level (1-3.5%, average 2.4%) has been found in 69%, and high protein level (3.6-6.5%, average 4.2%) in 31% of tested boars. There are not significant (P>0.05) influence of boars breed or age, as well of season of the year on the protein content in seminal plasma. In the native semen of tested boars was found on average 71% living, 13% of spermatozoa with damaged acrosome and 32% spermatozoa with morphological anomalies. Ejaculate volume, spermatozoa concentration, total number and motility percentage was significantly greater in the boars with high, compared with low protein content boars (p<0.01). Citomorphological properties of spermatozoa were tested by using CASA system and flow cytometry. Progressive motility - PP (64%) and living spermatozoa - LS (66%) was greater, while spermatozoa with damaged cell membrane - DM (19%), acrosome - DA (29%) and chromosome - DH (13%) was significantly (P<0.01) lower in the liquid semen with high protein content, stored for 72h in 1:4 dilution rate, compared with low protein content semen sample (PP=48%, LS=44%, DM=27%, DA=45% and DH=22%). Replacement of autologous seminal plasma from one boar with a low protein content, with homologous seminal plasma from another boar with a high protein content, significantly (p<0.01) increase progressive motility from 52% to 65%, in the samples stored for 72h in 1:4 dilution rate. Transcervical infusion of 30 ml seminal plasma, prior to classical AI dose application, significantly (p<0.05) increase farroving rate (94%) and live born piglets per litter (12.3) (p<0.01), compared with control (not infused) sows (83% and 10.5 piglets). Based on the obtained results, it can be concluded: (1) there are significant variation in the content of protein in seminal plasma between the boars, (2) semen samples from ejaculates with high protein content has a greater values of spermatozoa fertilizing vii potential, than samples from ejaculates with low protein content in seminal plasma, after storage for 72h at 1:4 dilution rate and (3) infusion of seminal plasma, prior to classical AI dose application, significantly increase sows fertility rate, compared with control sows. These findings indicate that protein content in seminal plasma can be useful tool for predicting boar fertility prior their using for AI, and that seminal plasma can be used for increasing fertility rate in the artificial inseminated sows. By the obtained results the working hypotheses was confirm and the investigation goals are achieved.