**4. What parameters could influence the AI success rate?**

The confirmation of pregnancies were performed by rectal palpation on average at around the 100th day. However, embryonic mortality is recorded in the same way as failure of fertilisation; this reduces the fertility results observed. Ultrasonographic preg‐ nancy diagnosis at 30 days would have been more accurate for measuring the fertili‐ ty of the semen as the impact of embryonic mortality is lower between D0 and D30 than between D0 and D150. Descoteaux et al. (2006) [16] thus report that 10% of cows that are given a positive pregnancy diagnosis at 28 days present with embryonic mor‐ tality at D60. Nevertheless, the cows included in the present study were selected as a function of various criteria that ensure satisfactory female fertility, which explains the difference in fertility recorded between the results of our study and those reported by Barbat et al. (2005) [17] and Freret et al. (2006) [18]. These studies are based on the results of inseminations conducted over a given period by insemination centres, with‐ out any selection criteria for the cows used. Female fertility was therefore inferior to that observed in our study. The observed fertility is a combination of the fertility of the male and female.

ways have intra-herd paired animals: the herd effect could not therefore be assessed. In this study, fewer constraints were voluntary imposed on the inclusion criteria as

Fertility Results After Artificial Insemination with Bull Semen Frozen with Low Density Lipoprotein Extender

The inseminator did not have a significant influence on the total Insemination Success Rate, with a threshold of significance of p=0.05 (Table 5). Inseminator 3 achieved high‐ er insemination success rates for both extenders McKenna et al. (1990) [25] calculated the inseminator effect at ± 9.5 points. The animals that he inseminated were on aver‐ age younger with a higher proportion of heifers. Barbat et al. (2005) [17] reported su‐

**TOTAL**

http://dx.doi.org/10.5772/51868

69

**193**

\*\*) 62.5 82

many animals as possible in order to facilitate the task of the inseminators.

**Inseminator 1 Inseminator 2 Inseminator 3**

n=12 n=12 n=11 n=15 n=16 n=16

n=13 n=15 n=11 n=12 n=10 n=10

n=17 n=8 n=2 n=4 n=6 n=3

54.8 71.4 54.2 48.4 68.7 75.8

n=42 n=35 n=24 n=31 n=32 n=31

\*\*: significant difference between the inseminators for Bull 1 with the LDL extender (p= 0.004)

\*: significant difference between the two extenders for Bull 1 when the insemination was performed by inseminator 1

**Table 5.** Insemination success rate (in %), details of the bulls and inseminators for each of the extenders, LDL and Tris

\*\*) 60.0 87.5(

38.5 73.3 36.4 41.7 50.0 90.0 71

88.2 50.0 50.0 25.0 50.0 100.0 40

extender LDL T.E.Y LDL T.E.Y LDL T.E.Y

\*) 72.2(

perior fertility in heifers in comparison with cows.

**Percentage success at insemination**

**(%)**

Bull 1

Bull 2

Bull 3

TOTAL

(p=0.002)

Egg Yolk (TEY)

25.0(

\*). (\*\*) 83.3(

In addition to the many different diseases that can affect fertility, other parameters may influence the fertility of cows as breed [17] or lactaction index [19]. In the study de‐ scribed here, the lactation index did not have any significant effect on the overall AI success rate (p<0.05). However, the lactation index had an impact for the LDL extend‐ er. Superior fertility was observed in the heifers, followed by the primiparous cows. A reduction in fertility was seen in cows with a lactation index of 2 or 3. There were insufficient numbers of cows with high lactation indexes to reveal any trends (Table 6). Milk production [18], energy profile [20], post-partum pathologies [21], and the herd effect [19] are other parameters that interfere with fertility results. Amman and Pick‐ ett (1987) [22] show that to measure male fertility a significant number of insemina‐ tions are necessary to rule out variations caused by female fertility. Van Wagttendonk de Leeuw et al. (2000) [23] demonstrate that to detect a 2% difference in the non-re‐ turn rate, with a confidence interval of 95% and a statistical power of 80%, 6,600 in‐ seminations are needed per extender. A limited population of 193 cows was inseminated as it was impossible to undertake a larger scale study due to the difficul‐ ty of convincing the breeders to use semen that had been frozen and thawed in an extender that did not have proven *in vivo* efficacy. The population was divided into two relatively homogeneous groups (mean lactation index, condition score, CFI) to lim‐ it variations in female fertility. The inclusion criteria could be improved: it would have been judicious to use only one breed to limit interbreed fertility differences [17]. It would also have been preferable for all of the cows to have the same lactation in‐ dex. The milk production of the animals affects their fertility [18]. The latter was not recorded as some of the farmers in this study did not keep individual milk produc‐ tion records. The use of condition scoring enables any animals that are in negative en‐ ergy balance to be excluded [24]. The bulls were chosen on the basis of good individual fertility and on the presence of the bulls at the centre at the time of se‐ men collection. The bull factor did not exert any significant difference (p<0.05) on the total insemination success rate (Table 5). The bull effect was observed in the sub-pop‐ ulation of cows that had been inseminated with the semen that had been frozenthawed in the LDL extender (p=0.019). The semen from bull 2 that had been frozen in Tris-egg yolk was significantly more fertile than that which had been frozen in the LDL (p=0.046). The variation in success for bull 3 was due to the small number of cows inseminated. The cows were taken from numerous farms and we did not al‐ ways have intra-herd paired animals: the herd effect could not therefore be assessed. In this study, fewer constraints were voluntary imposed on the inclusion criteria as many animals as possible in order to facilitate the task of the inseminators.

that are given a positive pregnancy diagnosis at 28 days present with embryonic mor‐ tality at D60. Nevertheless, the cows included in the present study were selected as a function of various criteria that ensure satisfactory female fertility, which explains the difference in fertility recorded between the results of our study and those reported by Barbat et al. (2005) [17] and Freret et al. (2006) [18]. These studies are based on the results of inseminations conducted over a given period by insemination centres, with‐ out any selection criteria for the cows used. Female fertility was therefore inferior to that observed in our study. The observed fertility is a combination of the fertility of

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

In addition to the many different diseases that can affect fertility, other parameters may influence the fertility of cows as breed [17] or lactaction index [19]. In the study de‐ scribed here, the lactation index did not have any significant effect on the overall AI success rate (p<0.05). However, the lactation index had an impact for the LDL extend‐ er. Superior fertility was observed in the heifers, followed by the primiparous cows. A reduction in fertility was seen in cows with a lactation index of 2 or 3. There were insufficient numbers of cows with high lactation indexes to reveal any trends (Table 6). Milk production [18], energy profile [20], post-partum pathologies [21], and the herd effect [19] are other parameters that interfere with fertility results. Amman and Pick‐ ett (1987) [22] show that to measure male fertility a significant number of insemina‐ tions are necessary to rule out variations caused by female fertility. Van Wagttendonk de Leeuw et al. (2000) [23] demonstrate that to detect a 2% difference in the non-re‐ turn rate, with a confidence interval of 95% and a statistical power of 80%, 6,600 in‐ seminations are needed per extender. A limited population of 193 cows was inseminated as it was impossible to undertake a larger scale study due to the difficul‐ ty of convincing the breeders to use semen that had been frozen and thawed in an extender that did not have proven *in vivo* efficacy. The population was divided into two relatively homogeneous groups (mean lactation index, condition score, CFI) to lim‐ it variations in female fertility. The inclusion criteria could be improved: it would have been judicious to use only one breed to limit interbreed fertility differences [17]. It would also have been preferable for all of the cows to have the same lactation in‐ dex. The milk production of the animals affects their fertility [18]. The latter was not recorded as some of the farmers in this study did not keep individual milk produc‐ tion records. The use of condition scoring enables any animals that are in negative en‐ ergy balance to be excluded [24]. The bulls were chosen on the basis of good individual fertility and on the presence of the bulls at the centre at the time of se‐ men collection. The bull factor did not exert any significant difference (p<0.05) on the total insemination success rate (Table 5). The bull effect was observed in the sub-pop‐ ulation of cows that had been inseminated with the semen that had been frozenthawed in the LDL extender (p=0.019). The semen from bull 2 that had been frozen in Tris-egg yolk was significantly more fertile than that which had been frozen in the LDL (p=0.046). The variation in success for bull 3 was due to the small number of cows inseminated. The cows were taken from numerous farms and we did not al‐

the male and female.

The inseminator did not have a significant influence on the total Insemination Success Rate, with a threshold of significance of p=0.05 (Table 5). Inseminator 3 achieved high‐ er insemination success rates for both extenders McKenna et al. (1990) [25] calculated the inseminator effect at ± 9.5 points. The animals that he inseminated were on aver‐ age younger with a higher proportion of heifers. Barbat et al. (2005) [17] reported su‐ perior fertility in heifers in comparison with cows.


\*: significant difference between the two extenders for Bull 1 when the insemination was performed by inseminator 1 (p=0.002)

\*\*: significant difference between the inseminators for Bull 1 with the LDL extender (p= 0.004)

**Table 5.** Insemination success rate (in %), details of the bulls and inseminators for each of the extenders, LDL and Tris Egg Yolk (TEY)


[2] Celeghini, E.C.C.; Arruda, R.P.; Andrade, A.F.C.; Nascimento, J.; Raphael, C.F.; Ro‐ drigues, P.H.M. Effects that bovine sperm cryopreservation using two different ex‐ tenders has on sperm membranes and chromatin. Animal Reproduction Science

Fertility Results After Artificial Insemination with Bull Semen Frozen with Low Density Lipoprotein Extender

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71

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state. Reprod Dom Anim 1996; 31: 279-280

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1996; 46(3), 413-420

1995;381-36.

\*: significant difference in the lactation index for the 8% LDL extender (p=0.005)

**Table 6.** Insemination success rates (in %) as a function of the lactation index
