Semen kinetics at collection. 1. note: comparison among cattle autochthonous genetic types (tga)

Abstract

The aim of the present research was to evidence the possible differences among 5 AGTs [Agerolese (AG), Burlina (BU), Bianca Val Padana (BVP), Garfagnina (GAR), Reggiana (RE)] in the values of kinetic parameters of the sperm cell, at collection; totally, the study was carried out on 19 bulls distributed according to genetic type as follows: 7 AG, 3 BU, 3 BVP, 3 GAR and 3 RE. A total of 73 samplings were carried out with a mean of 4 for bull. The following parameters were evaluated through computerized sperm analysis system (Hamilton Thorne Biosciences - IVOS) which uses appropriate algorithms: (a) Path Velocity (VAP, µm/sec) that estimates the progressive average position of the head in the observation field, hence the velocity of the average sperm path; (b) Progressive velocity (VSL, µm/sec) that estimates the velocity of the sperm between the beginning and the end of the track performed according to a straight line; (c) Track speed (VCL, µm/sec) that estimates the curvilinear velocity; (d) Straigthness (STR = VSL/VAP, %) that estimates the deviation of the sperm path from a straight line; (e) Beat Cross Frequency (BCF, Hz) that estimates the frequency with which a sperm, in its sinusoidal trend, cuts the mesor, considering a point of crossing as beginning of the inversion of the two phases; it is considered as final value equal to twice the frequency necessary to run through the whole wave; (f) Linearity (LIN = VSL/VCL,%) that estimates the deviation of the sperm track from a straight line; (g) Lateral Amplitude Head Displacement (ALH, µm) that estimates the mean amplitude width of the head oscillations as sperm swims; (h) Elongation (ELON, %) that estimates the ratio of head width to head length of the sperm (ELON 75 %); (i) Area (µm²), that estimates the mean head size of the sperm. The values of the parameters furnished by IVOS were corrected for the age of the bull at collection. The significance of the differences among the estimated means was tested by Student’s t test. The results, valid within the limits of the observation field, evidenced the significance (P > 0.05÷P > 0.001) among genetic types for the following parameters: (a) VAP in comparison with BU and BVP, BU and GAR as well as BVP and RE; (b) VSL in the comparison between AG and BVP, BU and BVP, BVP and RE as well as BU and GAR; (c) VCL in the comparison between AG and BVP, BU and BVP and BU and GAR; (d) ALH in the comparison between AG and BVP, BU and BVP as well as BVP and RE; (e) STR in the comparison between BVP and RE as well as GAR and RE; (f) BCF in the comparison between AG and RE, BU and RE as well as BVP and RE; (g) LIN in the comparison between AG and BVP alone; (h) ELON in the comparison between BVP and RE alone; (i) ‘Area’ in the comparison between AG and GAR as well as BVP and GAR. Considering all the parameters and all the possible comparisons among the AGTs, around 21 % of the comparisons among the AGTs resulted significant. The results evidenced that the correlation among some of the considered parameters, was significant (P >0.05 ÷P >0.001). In conclusion, the AGT is an important source of variation of the sperm characteristics; therefore, further research would be necessary to underline possible differences among the bulls within the AGT too, in order to obtain useful directions in the choice of the bull destined to the instrumental insemination, as integral element of the genetic value of a breed animal.