ABSTRACT:The objective was to determine effects of equilibration length and freezing curve type as well as their interactions on motility and live spermatozoa proportion in bull sperm after thawing. The ejaculates of 6 sires were repeatedly collected. Fresh semen was diluted with one extender and divided into 3 groups equilibrated for 30, 120, and 240 min. Subsequently, half straws of each group were frozen using standard 3-phase or 2-phase freezing curve differing in the rate of temperature decrease. Th e spermatozoa motility (M) was evaluated immediately after thawing and at 30, 60, 90, and 120 min of thermodynamic test (TDT). Live spermatozoa proportion was evaluated after thawing and at the end of TDT. Average of spermatozoa motility (AM), decrease of spermatozoa motility (MD), average proportion of live spermatozoa (ALS), and decrease of live spermatozoa proportion (DLS) through the TDT were calculated. Significant inter-sire differences in AM (0.45-17.0%; P < 0.05-0.01), MD (0.76-12.57%; P < 0.05-0.01), and ALS (0.99-23.8%; P < 0.01) were detected. The longest equilibration ensured the highest M during TDT and AM (+2.72 and +4.58%; P < 0.05-0.01), however higher MD (+4.06%; P < 0.01) compared to standard length as well. Straws freezed using 2-phase curve achieved higher M through TDT, AM (+7.3%; P < 0.01) as well as ALS (+11.77%; P < 0.01). The 2-phase curve presented higher M compared to the 3-phase freezing curve within all equilibration lengths. Significant differences in AM, MD,; P < 0.05-0.01) between equilibration length vs freezing curve interactions were determined. Results document the importance of equilibration length, freezing curve, and their interaction effect on live spermatozoa proportion and sperm motility after thawing as well as necessity of individual conditions for bulls semen processing and insemination doses production.

The objective of this work was to determine the effect of selected freezing curves on spermatozoa survivability after thawing, defined by its motility. The ejaculates of nine selected sires of the same age, breed, and frequency of collecting, bred under the same breeding conditions including handling, stabling, feeding system and feeding ratio composition, were repeatedly collected and evaluated. Sperm samples of each sire were diluted using only one extender and divided into four parts. Selected four freezing curves -the standard, commercially recommended threephase curve; a two-phase curve; a slow three-phase curve; and a fast three-phase curve, differing in the course of temperature vs time, were applied. The percentage rate of progressive motile spermatozoa above head was determined immediately after thawing, and after 30, 60, 90, and 120 min of the thermodynamic test (TDT). Moreover, average spermatozoa motility (AMOT) and spermatozoa motility decrease (MODE) throughout the entire TDT were evaluated. Insemination doses frozen using the simpler two-phase curve demonstrated the highest motility values (+2.97% to +10.37%; P < 0.05-0.01) immediately after thawing and during the entire TDT. Concurrently, the highest AMOT (+4.37% to +8.82%; P < 0.01) was determined. The highest spermatozoa motility values were detected after thawing doses frozen by the two-phase freezing curve in eight out of nine sires. Simultaneously, a significant effect of sire individuality was clearly confirmed. Inter-sire differences of spermatozoa motility during TDT as well as AMOT and MODE were significant (P < 0.01). The findings describing both factors of interaction indicate the necessity of individual cryopreservation of the ejaculate to increase its fertilization capability after thawing.

The aim of this study was to evaluate the effect of different thawing protocols (slow (P1), medium (P2), and fast (P3)) on percentage of motile sperm (MOT) and percentage of sperm cells with intact membranes (INT) in Holstein (4 bulls; 72 samples) and Czech Fleckvieh (4 bulls; 72 samples) semen frozen-thawed in 4 ml and 8 ml volumes. MOT was analysed in fresh semen, as well as immediately after thawing (T0) and 30 min after thawing (T30). INT was analysed using hypoosmotic swelling test (HOS test) in fresh ejaculate (FE), after diluting (DE), and at T0. The differences between FE parameters and frozen-thawed ejaculate parameters, expressing changes that occur during cryopreservation, were calculated. Apart from the effect of thawing protocol, the effect of breed and the effect of quality of FE expressed by MOT immediately after collecting were evaluated, too. Unlike thawing of semen cryopreserved in straws (0.25 and 0.5 ml), thawing using the slow protocol (P1) was the most appropriate (P &lt; 0.05) for both observed volumes. There were found significantly higher MOT in the volume of 8 ml in both T0 and T30 and in the volume of 4 ml in T30 in samples thawed using P1 and P2. MOT in T0 was significantly affected by breed in samples frozen in 8 ml and in T30 in samples frozen in 4 and 8 ml. There were found no significant differences in INT in all reported volumes, however decrease of INT during cryopreservation was affected by breed.

The aim of this study was to evaluate the effects of 3 different commercially available extenders – AndroMed® (soy lecithin-based), Optidyl® (with the addition of ionized egg yolk), and BULLXcell® (with the addition of fresh egg yolk) – on bull spermatozoa quality, which was evaluated using the parameters of spermatozoa motility, viability, plasma membrane damage, acrosome damage, and mitochondrial activity after thawing and during a 2 h long thermoresistance test. The spermatozoa quality indicators were appraised by computer-assisted semen analysis and a flow cytometer. Significant differences (P < 0.01) between bulls were registered in all indicators measured. The highest average values of spermatozoa total motility and viability were achieved using BULLXcell® extender (44.33%; 52.06%). Variances in comparing this extender with Optidyl® and AndroMed® were −0.83%, −2.64%; −8.33%, −9.51%. The differences found between the egg yolk-based diluents (BULLXcell® and Optidyl®) and AndroMed® were significant (P < 0.01). Therefore, the more valuable extenders for bull semen dilution were egg yolk-based extenders, which provided higher post-thaw spermatozoa survival and quality than the soy lecithin-based extender.

The present study assessed the effects of climatic conditions and year‑period (month) on both qualitative and quantitative characteristics of bovine semen in Czech Republic. The semen was collected twice a week using artificial vagina at artificial insemination center Hradištko in period 2011 – 2013. The effects of collection month, average daily ambient temperature and average daily relative humidity on volume, sperm concentration and progressive motility above head of collected semen and also on number of produced artificial insemination straws of required quality were analyzed using statistical analysis (procedures: UNIVARIATE, STEPWISE, GLM) in software SAS 9.3 (SAS/STAT® 9.3, 2011). Collection month, average daily ambient temperature, average daily relative humidity, and breed had a significant effect (P < 0.05) on all evaluated characteristics. The maximum values of motility and sperm concentration were found in March and in April. The highest volume of collected semen was found in July and in September and the lowest in November, when also the lowest number of straws was produced. Motility and sperm concentration were significantly influenced by average daily ambient temperature and average daily relative humidity, where the maximum values were recorded in average daily ambient temperature over 14.85 °C and average daily relative humidity over 72.05 %. The results are important to the management of artificial insemination center responsible for planning of semen collection, processing and artificial insemination straws production.

The aim of this study was to evaluate growth ability of Charolais calves in different systems of farming. The observations were performed in period of 8 years (2007 - 2014) in one herd, which was transiting from conventional to ecological farming system. Period from 2007 to 2010 was of conventional character, 2010 to 2012 transition phase, and from 2012 to 2014 ecological phase. This transfer is directly linked to changes in cow´s welfare and nutrition. Growth ability (live weight at birth, 120, and 210 days of age, average daily gain from birth to 120, from birth to 210, and from 120 to 210 days of age) of 518 Charolais calves was measured. Statistical analyses were performed using SAS 9.3 software, GLM procedure. The model equations contend effect of sex, number of parity, month of calves birth and type of farming system. Difference in birth weight of calves between farming systems was small and insignificant. This fact may be due to breeding system focused on easy calving. Increase of values measured in different age and average daily gains were statistical significant (P < 0.05) between conventional and ecological farming. The increase of parameters of weight and average daily gain could be largely connected with genetic progress in Charolais population in Czech Republic and following good selection of bulls to insemination and natural breeding. Nevertheless, the transition from conventional to ecological farming system did not affected growth ability of beef cattle negatively and, in contrary, results of growth improved farm economy.