Semen characteristics of boars receiving control diet and control diet supplemented with L-carnitine

The objective of this experiment was to test a hypothesis that L-carnitine supplemented diet would improve semen characteristics in 6 adult crossbred AI boars (Hampshire × Pietrain). The control and the tested diet were identical except the tested period (8 weeks) when the diet was supplemented with 2 g of L-carnitine per boar per day. The semen was collected regularly weekly by a gloved-hand technique. Semen volume, sperm motility and concentration, proportion of alive sperm cells and aspartate aminotransferase (AspAT) activity of semen were determined immediately after the semen collection once every two weeks. Sperm survival rate, morphologically abnormal spermatozoa, seminal plasma mineral components and free amino acid concentration, L-carnitine concentration in semen plasma and in sperm cells were determined after the sample storage (-20°C) at a later time. The differences ascertained between the average values of semen characteristics in the control vs. tested period did not prove a true and unambiguous positive effect on boar semen parameters by dietary supplementation of L-carnitine as our data show in our study: volume (239.11 vs. 250.50 ml; P 0.518), sperm concentration (301.67 vs. 350.83 × 103/mm3; P 0.309), sperm progressive motility (66.94 vs. 70.00%; P 0.409), morphologically abnormal spermatozoa (29.00 vs. 27.46%; P 0.802), daily sperm cells output (9.86 vs. 11.71 × 109; P 0.206), proportion of alive sperm cells (72.56 vs. 74.13%; P 0.484), survival spermatozoa ability maintenance (43.29 vs. 38.68%; P < 0.01), mineral components in the seminal plasma (Na-, K-, Ca-, Mg-, Zn-; P from 0.138 to 0.968), AspAT activity (in semen plasma - 132.50 vs. 128.31 mU/109 spermatozoa; P 0.830, in sperm cells - 147.37 vs. 119.01 mU/109 spermatozoa; P 0.146), semen plasma amino acid concentration - a significant positive effect of L-carnitine in lysine only (0.79 vs.1.17 μmol/100 ml; P < 0.01), L-carnitine concentration (in semen plasma 255.40 vs. 259.97 mg/l; P 0.884, in sperm cells - 1 110.68 vs. 883.58 mg/l; P < 0.01). In conclusion, the studied indicators of semen quality were not significantly enhanced by dietary supplementation of L-carnitine in adult AI boars.