**3. Is there a correlation between motility and fertility?**

Pregnancies were obtained following the artificial insemination of cows with semen that has been frozen-thawed in an LDL extender without any significant difference in the success rate following insemination between the 2 extenders. The initial objective was not to demonstrate the superiority of the LDL extender, but to demonstrate its effica‐ cy in the field in terms of percentage gestation. The success rates with artificial insemi‐ nation are satisfactory (table 3): 59.2% for the LDL extender and 65.3% for the Trisegg yolk extender. In a previous study, Amirat et al.2004 [6] demonstrated that fertility was maintained *in vitro*. The hypoosmotic test was chosen to assess plasma mem‐ brane integrity as a proven correlation has been found between the results of the HOS test and the *in vivo* fertility rate [9]; the HOS test can therefore be used to predict fer‐ tility. Plasma membrane integrity was maintained with both the LDL and Tris-egg yolk extenders (table 2). These results concur with previous studies undertaken in the bo‐ vine species [10,11]. Around 60% of the spermatozoa that were frozen-thawed in the LDL extender presented with an alteration of the plasma membrane, whilst around 40% of the spermatozoa lost their motility. The percentage of spermatozoa with an al‐ tered plasma membrane may be higher than to the percentage or spermatozoa present‐ ing with a loss of motility. This implies that a certain number of spermatozoa may retain their motility with a damaged plasma membrane, this result agree with that re‐ ported by Salamon and Maxwell (1995) [11]. Nevertheless it is unlikely that such sper‐ matozoa would be capable of crossing the zona pellucida.

**Extender Total spermatozoa (n)** Swollen spermatozoa (intact)

LDL 8% 1296 542 41.8 Tris-Egg yolk 1314 559 42.5

> LDL n=98

> > n=67 n=22 n=7 n=1 n=1

1.6 ± 1.9 n=29 n=28 n=20 n=9 n=6 n=6

94 ± 25 (1 CFI not given)

**Positive pregnancy**

LDL 98 58 40 59.2 Tris-Egg yolk 95 62 33 65.3

Pregnancies were obtained following the artificial insemination of cows with semen that has been frozen-thawed in an LDL extender without any significant difference in the

**Table 4.** Effect of the extender used for freezing the semen on the success rate at insemination (as a %)

**3. Is there a correlation between motility and fertility?**

to the HOS test N = sum of spermatozoa taken from Bulls 1, 2, and 3.

66 Success in Artificial Insemination - Quality of Semen and Diagnostics Employed

Characteristics of the population

> Holstein Normandy Charolais Charolais cross Aubrac

Mean ± standard dev.

**Breeds**

Lactation index

Condition score

(mean ± standard deviation)

(mean ± standard deviation)

**Extender**

Calving to first insemination interval in days

**Table 3.** Characteristics of the study population for each extender

**Cows inseminated (N)**

**Table 2.** The effect of LDL and Tris-egg yolk extenders on the integrity of spermatozoal plasma membranes according

(n) (%)

Tris egg yolk n=95

n=81 n=5 n=9

1.5 ± 1.5 n=31 n=24 n=19 n=12 n=5 n=4

95 ± 32 (1 CFI not given)

> **Success rate at insemination (%)**

3.0 ± 0.2 3.0 ± 0.3

**diagnosis Not pregnant**

Motility results demonstrate that the percentage of motile spermatozoa following thaw‐ ing is superior in the LDL extender in comparison with the Tris-egg yolk extender. These results concur with the works of Moussa et al. (2002) [5] and Amirat et al. (2004) [6]. However, inter-individual variability on the motility performances following thaw‐ ing has already been reported by Farrell et al. (1998) [12] and Holt (2000) [13]. The results obtained do not make it possible to relate the motility of the spermatozoa to fertility due to the insufficient number of measurements. No study has demonstrated a precise correlation between motility parameters and fertility in cows. In cattle, the percentage of mobile spermatozoa, linearity (LIN), and straight line velocity (VSL) seem to be correlated to fertility according to Budworth et al. (1988) [14], and Farrell et al. (1998)[12]. The average path velocity (VAP), curvilinear velocity (VCL), and the fre‐ quency of tail movements (FTM), also appear interesting [12]. According to Liu et al. (1991) [15], the most interesting motility parameters in human semen are linearity (LIN), straight line velocity (VSL), and the percentage of rapid spermatozoa.
