FR3042868A1 - METHOD FOR DETERMINING THE QUALITY OF A SEED OF A GREEN ANIMAL - Google Patents

Abstract

The invention relates to a method for determining the quality of a seed of a vertebrate animal. According to the invention, such a method comprises the following steps: measuring at least one absorption spectrum of a sample of said seed; selecting a number n, with n ≥ 7, of wave numbers δj (j∈ [1; n]) characteristic of the seeds of the race or species of said animal; determination from said absorption spectrum (s) of a value of the absorption Xj and / or a value of the second derivative of the absorption Xj "(j∈ [1; n]) for each of said n wave numbers δj (j∈ [1; n]); - calculating a non-return rate Y at a predefined number of days from said values of the absorption Xj and / or the second derivative of the "absorption Xj" previously determined.

Description

FIELD OF THE INVENTION The invention relates to the field of breeding and in particular to the breeding of livestock, avians and fish.

More specifically, the invention relates to a method for determining the quality of a seed of a vertebrate animal. The invention finds particular application in the selection of a quality seed to improve the success rate of insemination of an animal in a breeding or in the control of the quality of the seed of breeders. 2. State of the art

In the field of livestock breeding, insemination is an important step towards optimizing herd management. This step is all the more crucial as it helps to maximize the milk production periods, for example in the case of dairy cows. For these reasons, the quality of the insemination and thus the seed used is essential.

Indeed, an insemination that does not lead to a gestation of the animal has a negative impact on the profitability of a breeding. For example, for a cow, the success of an insemination is estimated by the absence of a return to estrus recorded during a period of 90 days after the act of insemination. In case of failure, the annual milk production of the animal concerned is directly impacted downward. This translates into a decrease in operating income for the farmer. In addition, the insemination operation must be repeated. It is therefore important to reduce the uncertainties associated with this intervention.

For example, the evaluation of seed quality is a major challenge for analytical laboratories and seed producers.

This quality was first estimated according to animal selection protocols. However, it has been found that an animal with a very good genetic makeup does not necessarily turn out to be a good breeder. In addition, the quality of the semen of an animal selected for its good overall reproduction rate may vary according to the health of the animal during the sampling.

We then tried to evaluate the quality of the collected semen. This quality was evaluated from the seed as a whole and / or from its different components according to different criteria.

The seed is a complex biological fluid, consisting of the secretions of different organs of the reproductive tract, in which the male gametes bathe. The semen consists of spermatozoa, seminal plasma and exosomes.

Fertility, which is the ability to procreate, is a consensus term for assessing the quality of a seed. However, this term has the disadvantage of being general and vague. It is unsatisfactory to discriminate against male individuals. Therefore and according to the needs, different criteria have been defined in order to evaluate the fertility of an individual.

These criteria include: the fertilization rate, which is the rate of fusion between the male and female gametes allowing the formation of the zygote; TNR, an acronym for non-return rate, is an estimate of the outcome of successful or unsuccessful insemination based on the absence of a return to estrus during an X-day interval after the act of insemination; the conception rate, which is the percentage of females diagnosed in pregnancy during an interval of X days after the act of insemination (DeJarnette JM, Amann, RP, "Understanding estimates of AI fertility: From A to Z." 23rd Technical Conference on Artificial Insemination & Reproduction, Milwaukee, WI, 2010).

A difficulty is that a measurement of these different criteria requires, to obtain a result, a more or less long wait depending on the species or breeds of animals.

Many in vitro tests have therefore been developed to evaluate the semen, some of which are recommended in human clinical practice by the World Health Organization (WHO). World Health Organization, 2010). In humans as in other vertebrate species, existing tests are unsatisfactory in predicting the fertility of a sperm sample analyzed (De Jonge C. "Fertil Steril Semen analysis: looking for an upgrade in class." 2012 - 97: 260-266 and Kastelic JP, Thundathil JC. "Breeding soundness evaluation and semen analysis for predicting bull fertility." Reprod Domest Anim Zuchthyg 2008; 43 Suppl 2: 368-373). Macroscopic tests (volume, color, viscosity ...) and microscopic (motility, concentration, morphology ...) currently performed routinely eliminate seeds with extremely poor qualities, but are not conclusive to identify infertility idiopathic and hypofertile animals. In addition, they do not allow, for example, to predict the variability of bullfighting observed in the field. This difficulty lies, among other things, in the fact that spermatozoa are complex cells and that their evaluation has some difficulties (Mocé E, Graham JK, "In vitro Evaluation of Sperm Quality." Anim Reprod Sci 2008; 105: 104-118).

One of the problems inherent in assessing the quality of a seed is that the sample contains a heterogeneous sperm population. As a result of their training during spermatogenesis, the spermatozoa pass through the epididymis and accumulate in the tail of this organ until the time of ejaculation (Dacheux JL, Dacheux F. "New insights into epididymal function relationship to sperm ripening. "Reprod Camb Engl 2014; 147: R27-42). Spermatozoa thus stored come from different waves of spermatogenesis, so sperm from the same ejaculate have different degrees of maturation ensuring, in vivo, a wider window of fertilization. In vivo during their transit through the female reproductive tract, some spermatozoa are eliminated from the population. On the other hand, during the in vitro analysis of a seed, the sample may comprise several infertile spermatozoa, which may be immobile, dead, poorly formed, etc. (Holt WV, Van Look KJW, "Concepts in sperm heterogeneity, Reprod Camb Engl 2004; 127: 527-535 and Rodriguez-Martinez H. "Reprod Domest Anim Zuchthyg 2006; 41 Suppl 2: 2-10 and Petrunkina AM, Volker G, Brandt H, Topfer-Petersen E, Waberski D. "Functional significance of responsiveness to capacitating conditions in boar spermatozoa." Theriogenology 2005; 64: 1766-1782). Thus, the sperm infertile are evaluated in the same way as those who will be able to fertilize the egg.

Another problem inherent in assessing the quality of a seed is that sperm do not respond uniformly to the same stress (Petrunkina AM, Volker G, Brandt H, Topfer-Petersen E, Waberski D. "Functional significance of responsiveness to capacitating conditions in boar spermatozoa. "Theriogenology 2005; 64: 1766-1782), although these spermatozoa have similar characteristics at specific times. Finally, the complexity of working with sperm also comes from the fact that this cell is multicomponent and that each of these sub-compartments must be intact and functional to allow fertilization (Amann RP, Flammerstedt RFI. "In vitro evaluation of sperm quality: an opinion. "J Androl 1993; 14: 397-406).

To ensure fertilization, spermatozoa must have several characteristics such as mobility, ATP production, induction of hyperactivation, ability to achieve their capacitation and acrosomal reaction, functional plasma membrane, ability to recognize and to bind to the zona pellucida, or to have intact DNA, etc. Spermatozoa are thus complex, multifunctional cells requiring the proper functioning of several parameters to reach their ultimate goal: fertilization and support of early embryonic development. The infertility or subfertility of an individual can be the consequence of a multitude of modifications.

Thus, a test evaluating one of the sperm parameters has difficulty in detecting a defective spermatozoon for a property other than that evaluated by the test. A disadvantage of such a test is to overestimate the fertility of the sample (Graham JK, Mocé E. "Fertility Evaluation of frozen / thawed semen." Theriogenology 2005; 64: 492-504). In addition, it is unlikely that this laboratory test evaluating a sperm parameter will be able to detect the proportion of sperm containing all the parameters necessary to fertilize the oocyte and ensure embryonic development. This is why multiparametric tests are interesting. Indeed, the analysis of several parameters of a sperm sample makes it possible to obtain an overall view of the analyzed sample and improves the detection of a deficient parameter. In this way, multiparametric analysis could better explain the differences in fertility between the different bulls analyzed (Januskauskas A, Johannisson A, Soderquist L, Rodriguez-Martinez H. "Assessment of sperm characteristics post-thaw and response to calcium ionophore relation to fertility in Swedish dairy AI bulls. Theriogenology 2000; 53: 859-875).

Another part of the problem encountered in assessing the fertility of an animal from laboratory results results from problems underlying the laboratory analysis itself. To be valid, a laboratory test should be objective (create little error due to human judgment or bias), repeatable (produce the same results when repeating the test), accurate (accurately assess a parameter of spermatozoa), rapid and inexpensive (Graham JK, "Assessment of sperm quality: a flow cytometry approach." Anim Reprod Sci 2001; 68: 239-247). Currently, few laboratory tests to analyze the seed have all of these characteristics.

In recent years, the use of the Computer Assisted Sperm Analysis (CASA) analysis technique and the flow cytometry analysis technique has allowed the evolution of quality evaluation methods for a seed. in laboratory.

A disadvantage of these multiparametric assay techniques is that they do not allow in vitro predictive measurement of in vivo fertility. This lack of conclusive results can be attributed to the parameters and markers used for these tests, which are too weakly correlated with the phenotype to be predicted and / or are redundant and / or are limited in number.

The broadband approaches grouped under the term "omics" or "phenomics" allow more and more in-depth evaluations of the quality of a seed with interesting perspectives as well in human clinical (Egea RR, Puchalt NG, Escriva MM, Varghese AC OMICS: "Current and future perspectives in reproductive medicine and technology." J Hum Reprod Sci 2014; 7: 73-92) in agronomy (Robert C. "Challenges of functional genomics applied to farm animal gametes and pre-hatching embryos. Theriogenology 2008; 70: 1277-1287).

A disadvantage for the routine use of these known techniques stems from their costs.

Another disadvantage is the complexity of the implementation of these techniques.

A further disadvantage is that these known techniques are made from a fraction of a sample and not an intact sample. Other techniques have been proposed to allow the analysis of intact cells, and in particular to determine their lipidome (Jones JJ, Stump MJ, Fleming RC, Lay OJ, Wilkins CL.) Strategies and data analysis techniques for lipid and phospholipid chemistry elucidation by intact cell MALDI-FTMS. "J Am Soc Mass Spectrom 2004; 15: 1665-1674) or their proteome (Labas V, Spina L, Belleannee C, Teixeira-Gomes AP, Gargaros A, Dacheux F, Dacheux JL. of epididymal sperm maturation by MALDI profiling and top-down mass spectrometry. J Proteomics 2015; 113: 226-243).

A disadvantage of these intact cell analysis techniques is that they do not permit the characterization of intact spermatozoa for a set of molecular and / or structural characters simultaneously.

A technique for analyzing the quality of a seed by infrared spectroscopy is also known, which more particularly consists in analyzing an irradiated sample under a radiation in the mid-infrared (the wavelength of the radiation is between 2.5 pm and 25 pm), also known by the acronym MIR (acronym for "mid-infrared").

When a biological sample is irradiated with MIR radiation, the radiation will be partially and selectively absorbed depending on the chemical bonds of the different molecules present in the sample. An infrared spectrum is therefore composed of absorption bands that can be attributed to specific chemical groups. The position of the bands depends both on the nature of the link, but also on its environment. Thus, the position of the absorption band makes it possible to connect these absorption bands to particular molecules such as proteins, lipids or carbohydrates.

Studies have been conducted to evaluate the performance of the mid-infrared spectroscopy technique for different applications. For example, a study for bacterial typing (Helm D, Labischinski H, Schallehn G, Naumann D. "Classification and identification of bacteria by Fourier-transform infrared spectroscopy." J Gen Microbiol 1991; 137: 69-79; Stamm I, Hailer M, Depner B, Kopp PA, Rau J. "Yersinia enterocolitica in diagnosis fecal samples from European dogs and cats: identification by fourier transform infrared spectroscopy and matrix-assisted laser desorption ionization-time of flight mass spectrometry." Clin Microbiol 2013; 51: 887-893), a study on the identification of pathologies such as cancer (Backhaus J, Mueller R, N Formanski, Szlama N, Meerpohl HG, Eidt M, Bugert P. "Diagnosis of breast cancer with infrared spectroscopy from serum samples. "Vib Spectrosc 2010; 52: 173-177; and Kallenbach-Thieltges A, GroBerüschkamp F, Mosig A, Diem M, Tannapfel A, Gerwert K." Immunohistochemistry, histopathology and infrared spectral histopathology of colon cancer tissue s ections. "J Biophotonics 2013; 6: 88-100; and Lewis PD, Lewis KE, Ghosal R, Bayliss S, AJ Lloyd, Wills J, Godfrey R, Kloer P, LAJ Wall. Evaluation of FTIR spectroscopy as a diagnostic tool for lung cancer using sputum. BMC Cancer 2010; 10: 640), or joint pathologies (Canvin JMG, Bernatsky S, Hitchon CA, Jackson M, Sowa MG, JR Mansfield, Eysel HH, HH Mantsch, El-Gabalawy HS. "Infrared spectroscopy: shedding light on synovitis in patients with rheumatoid arthritis. "Rheumatol Oxf Engl 2003; 42: 76-82), or the detection of contaminants in the food industry (Carvalho BMA, Carvalho LM, Reis Coimbra JS back, Minim LA, Souza Barcellos E, da Silva Jûnior WF, Detmann E, Carvalho GGP, "Rapid detection of whey in milk powder by spectrophotometric and multivariate calibration." Food Chem 2015; 174: 1-7). Infrared spectroscopic evanescent wave spectroscopy known by the acronym FEWS (of the English "Fiber Evanescent Wave Spectroscopy") allows to work in the MIR. This analysis is based on the use of a sensor composed of a chalcogenide glass optical fiber which is described, for example, in the documents FR2958403, WO2013017324, and FR1450661. When a light wave propagates in an optical fiber, it does so by multiple reflections, all of these rays constituting the evanescent wave. This wave can then be absorbed by a medium in contact with the fiber.

This technique offers many advantages. Contrary to the discrete analyzes which aim at researching and / or quantifying certain metabolites defined a priori, the MIR analysis makes it possible to obtain an overall image of the metabolic profile of the sample in a single analysis thus taking into account the interactions between molecules. The particularity of the fiber optic sensor makes it a tool that can be used in a liquid medium while being little sensitive to the water content of the samples, unlike other acquisition techniques. The result is fast and does not require special treatment of samples.

Several uses of Raman spectroscopy have already shown insights into the potential of this technique applied to the field of reproduction (Mallidis C, Sanchez V, Wistuba J, Wuebbeling F, Burger M, Fallnich C, Schlatt S. "Raman microspectroscopy: shining a new light on reproductive medicine. "Hum Reprod Update 2014; 20: 403-414). This technique has been applied to the evaluation of the integrity of sperm DNA (Mallidis C, Wistuba J, Bleisteiner B, Damm OS, Gross P, Webbeling F, Fallnich C, Burger M, Schlatt S. "In situ Raman microspectroscopy, Hum Reprod Oxf Engl 2011; 26: 1641-1649; and Mallidis C, Schlatt S, Wistuba J, Fallnich C, Gross P, Burger M, Wuebbeling F. "Means and methods for assessing sperm nuclear DNA structure. "WO2013064159 A1, 2013), the analysis of the acrosome to determine the fertilizing power of a spermatozoon (STiTft, χϋΐ ^." Sperm acrosome Raman area spectrum peak and use thereof. "CN103698310 A, 2014) or seminal plasma analysis for diagnostic purposes (Huang Z, Chen X, Chen Y, Chen J, Dou M, Feng S, Zeng H, Chen R. "Raman spectroscopic characterization and differentiation of seminal plasma. "J Biomed Opt 2011; 16: 110501-1105013).

However, it has never been used to date to characterize a complete sample of semen. OBJECTIVES OF THE INVENTION The object of the invention is therefore in particular to overcome the disadvantages of the state of the art cited above.

More specifically, the invention aims to provide a method for determining the quality of a seed of a vertebrate animal that is effective and reliable for any type of seed.

Another object of the invention is to provide such a technique that is simple and quick to implement. The invention also aims to propose a method for determining the quality of a seed of a vertebrate animal that is of a reduced cost. 4. Presentation of the invention

These objectives, as well as others that will appear later, are achieved by a method of determining the quality of a seed of a vertebrate animal.

In the context of the invention, the term "animal" in its current meaning, namely a non-human heterotrophic living being. In other words, the invention relates to a method for determining the quality of a seed of a non-human vertebrate. For example, they may be cattle, small livestock, an avian or a fish.

According to the invention, such a method comprises the following steps: measuring at least one absorption spectrum of a sample of said seed; selecting a number n, with n> 7, of wave numbers aj (I [i; n]) characteristic of the seeds of the race or species of said animal; determination from said absorption spectrum or spectrums of a value of the absorption Xj and / or a value of the second derivative of the absorption Xj "(Mi; n]) for each of said n numbers of waves aj (i [i; n]); - calculating a non-return rate Y at a predefined number of days from said values of the absorption Xj and / or the second derivative of the absorption Xj " previously determined.

Thus, in an unprecedented manner, the invention proposes using the absorption spectrum of a seed to evaluate the quality of a seed of an animal, from a reduced number of representative wave numbers of variables. explanatory characteristics of the seeds of the race or species of the animal. The invention makes it possible in particular to determine a non-return rate, for example a rate of no return in heat at 22, 28, 30, 56, 90 or 120 days, for 98% of the seeds of a race or a animal species with an accuracy of ± 10 points, from only 20 explanatory variables, and with an accuracy of ± 5 points for 86% of the seeds. It is recalled that the rate of non-return at D days (TNRJ) is an estimate of the result of insemination, success or failure, based on the absence of a return to estrus recorded during a J-day interval. after the act of insemination. After D days, cows not returning to estrus are considered pregnant.

It should also be noted that the invention makes it possible to evaluate the quality of seeds of all races or species of vertebrate animals, without exception, quickly and at low cost.

In the context of the invention, the term animal breed, within the same animal species, a population of individuals homozygous for a certain number of characters conditioning a set of traits or morphological particularities and the same general trend of within the same animal species, such as, for example, a bovine breed, an equine breed, a porcine breed, a sheep breed, a goat breed, a duck breed, a chicken breed, a goose breed, a breed of turkey, a breed of rabbit,

According to one particular aspect of the invention, said non-return rate Y is calculated according to the mathematical law

where Xj "(I [i; n]) is the normalized second derivative of the absorption for the number of waves aj and the weighting coefficients β0 and (I [i; n]) are constants.

The non-return rate is thus deterministically calculated.

Preferably, the values of said weighting coefficients are obtained from a processing of the absorption spectra measurements of a plurality of seed samples of a reference vertebrate population, the non-return rates of which are known.

According to an advantageous embodiment of the invention, during said measuring step, at least 2, preferably at least 3 absorption spectra of a sample of said seed are measured and said step of determining values of the absorption and / or second derivatives of the absorption comprises a step of producing an average of said measured spectra from which said absorption values and / or second derivatives of the absorption are determined.

This reduces the sensitivity to measurement artifacts and disturbances.

Advantageously, the number n of wave numbers aj (I [i; n]) is greater than or equal to 9, preferably greater than or equal to 20.

The accuracy of the seed quality assessment is increased by taking into account a larger but limited number of wave numbers.

According to a preferred aspect of the invention, said wave numbers are each representative of a molecule or a set of molecules selected from the group comprising at least: lipids; carbohydrates; proteins; nucleic acids; combining a lipid, carbohydrate, protein, or nucleic acid molecule with at least one other lipid, carbohydrate, protein, or nucleic acid molecule.

For example, for a bull, we can choose from about 600 explanatory variables.

In a particular embodiment of the invention, said vertebrate is a bull and the rate of no return is a 90-day non-return rate, said bull coming from a breed selected from the group comprising at least one animal. 'Abundance, Béarnaise, Bordelaise, Bretonne Pie Noir, Brune, Froment du Léon, Jersiaise, Montbéliarde, Red Pie des Plaines, Prim'Holstein, Flemish Red, Northern Blue, Normandy , the Salers, the Tarentaise.

According to a particular embodiment of the invention, said wave numbers aj ϋε [ι; η]) are chosen from the group comprising at least 955.0 ± 0.1 cm_1, 963.1 ± 0.1 cm ' 1, 1012.1 ± 0.1 cm -1, 1036.6 ± 0.1 cm -1, 1095.8 ± 0.1 cm -1, 1124.3 ± 0.1 cm -1, 1136.6 ± 0, 1 cm -1, 1365.1 ± 0.1 cm -1, 1383.5 ± 0.1 cm -1, 1428.4 ± 0.1 cm -1, 1444.7 ± 0.1 cm -1, 1452.9 ± 0.1 cm -1, 1503.9 ± 0.1 cm -1, 1520.2 ± 0.1 cm -1, 2805.7 ± 0.1 cm -1, 2956.7 ± 0.1 cm -1. 1, 2969.0 ± 0.1 cm -1, 2987.4 ± 0.1 cm -1, 3089.4 ± 0.1 cm -1, 3091.4 ± 0.1 cm -1.

Preferably, said step of measuring at least one absorption spectrum comprises a step of preparing said sample from said seed.

In a particular embodiment of the invention, the method for determining the quality of a seed as described above comprises a step of comparing said non-return rate Y with a predetermined threshold, making it possible to select said seed. for reproduction purposes in the case where said non-return rate Y is greater than or equal to said predetermined threshold.

There is thus an effective technique and particularly simple to implement to select quality seeds.

In an advantageous embodiment of the invention, said threshold is greater than or equal to 0.4, preferably greater than or equal to 0.5, and even more preferably greater than or equal to 0.6. 5. List of Figures Other features and advantages of the invention will appear more clearly on reading the following description of an embodiment of the invention, given as a simple illustrative and non-limiting example, and drawings. in which: FIG. 1 illustrates, in block diagram form, the steps of an exemplary embodiment of a method for determining the quality of a semen of a bull according to the invention; FIG. 2 represents MIR, derivative and normalized spectra acquired from a flake, a supernatant and a pellet; Figure 3 is a representation of the variance of a straw and a pellet from the same ejaculate as a function of the wave number; FIGS. 4A, 4B and 5 illustrate the correlation between values of TNR90 calculated by a wave number model for samples of ejaculate of prim'holstein bulls and known values for these same samples, respectively for 70 samples, for 16 other samples and for all of these 86 samples; FIG. 6 is another representation of FIG. 5 on which two straight lines representative of a difference in the value of the TNR90 with respect to the model of +5 points and -5 points, respectively, are added. 6. Detailed description of the invention 6.1. Experimental protocol

The analyzed samples are bovine ejaculates in the form of flakes, preserved in liquid nitrogen. Preliminary analyzes were performed on 130 ejaculates from 50 different Prim'Holstein breed bulls. The TNR90brut indicator was used to qualify the quality of ejaculates. 6.1.1. Sample preparation

In the sample preparation phase, in a first step, the flakes are thawed in a water bath at 37 ° C for 30 seconds. In a second step, the flakes are analyzed. For this, the contents of the flakes are placed in a 1.5 ml Eppendorf tube. Seven microliters are then deposited on the sensor for spectral acquisition MIR of a "straw". In a third step a supernatant is extracted by centrifugation at 3500 g for 5 min at 15 ° C. The supernatant is then deposited on the sensor for the acquisition of the "supernatant" spectrum. In a fourth step, the pellet is rinsed with 600 μl of NaCl 0.9% and centrifugation is done. The pellet is again suspended in 3.5 μl of NaCl 0.9% and deposited on the sensor for the acquisition of the "pellet" spectrum. 6.1.2. Spectral acquisition MIR of a straw

The spectra are acquired in absorbance of 4000 to 400 cm -1. The spectral resolution is fixed at 4 cm_1, with a zero-filling factor of 2, and 64 scans are recorded.

A sensor is placed in the spectrometer, the baseline is recorded to calibrate the device, then 7 μΙ of sample is deposited on the sensor. The spectrum is recorded after 6 minutes. 6.1.3. Spectrum processing

The spectra are analyzed in the 3800-940cm domain of absorption of most biomolecules. A straight line is generated from 2800 to 1800 cm -1 to eliminate the contribution of CO2, then the second derivative (Savisky-Golay algorithm with 13 smoothing points) is calculated from 3200 to 2800 cm -1 and 1800 to 940 cm -1. 1. Then, a vector standardization of the second derivatives is carried out Quality criteria are defined to reject the non conforming spectra 6.1.4 Choice of the matrix for the prediction of the quality of the seed

Three types of acquisitions were made and compared: ejaculate or total seed, pellet and supernatant (centrifugation of the seed). An observation of the spectra (see FIG. 2) shows that the "flake" 210 and "supernatant" spectra 220 have many similarities. A Principal Component Analysis (PCA) is performed on the data to compare the spectra. It appears on the factorial map that the spectra acquired from the supernatant are very close to those acquired from the total ejaculate. Thus spectra acquired from flakes contain biochemical information very close to that of seminal fluid. However, the latter is strongly diluted (3 to 30 times) in a buffer before freezing and is therefore not determinant of the specific quality of the diluted / frozen / thawed semen of the bull since all the ejaculates are treated in the same way. way. Due to the greater or lesser dilution of the ejaculate, the MIR spectra of the flakes necessarily reflect the biochemical composition of the dilution medium. This contribution to the MIR spectra may therefore mask that of the spermatozoa that are supposed to contain the spectral information that makes the difference from the point of view of fertility. Moreover, if a fertility defect linked only to a lower quality of the seminal fluid (fructose, pH, ...) is considered, it is expected that this defect is compensated by the dilution in the buffer medium. It turns out that the spectral information that establishes the difference is to be found on the cells alone, rather than on the overall sample more or less diluted. The variability of the measurements between straw and pellet 230 was also taken into account. For this, the variances were calculated on the 3 spectra acquired for the same ejaculate. The raw spectra, that is to say the non-derivative spectra, were first standardized by the anti-scattering (MSC) method (Multiplicative Scatter Correction) in order to avoid line variations. basic. As shown in FIG. 3, with a representation of the variance as a function of the number of waves (in cm -1) for an analysis of the flakes 310 and of the cap 320, it generally appears that the signals acquired from the Total seed show more variability especially in the 1000-940cm1 area.

The measurements are therefore carried out on the centrifugation pellet essentially containing the spermatozoa. 6.2. Construction of models for determining the quality of a seed 6.2.1. Reference samples

Eighty-six ejaculates, derived from 40 Prim'Holstein bulls, with a 90-day no-return rate, or gross NRN90, are used to establish the law or equation for determining quality of the ejaculate.

These ejaculates come from bulls aged 11 months to 10.5 years at the time of collection of their ejaculates. The distribution of the number of ejaculates per bull is as follows: 8, 18 and 14 bulls produced respectively 1, 2 or 3 ejaculates. 6.2.2. Glitter preparation

For each ejaculate, six straws are thawed by placing them in a water bath at 37 ° C for 30 seconds.

The contents of the six flakes are emptied into a 1.5 ml Eppendorf tube and then centrifuged at 3500 g for 5 minutes at 15 ° C. The supernatant is removed and the pellet is rinsed with 600 μl of 0.9% NaCl. This step is renewed once. Following the second rinse, a new centrifugation is applied and the pellet is suspended again in 10 μl of 0.9% NaCl. 6.2.3. Acquisition of the spectra From this preparation, we proceed to the acquisition of three spectra for each ejaculate. The acquisition of each of the spectra is carried out with a step of 2 cm -1, on a spectrometer whose precision, whatever the position, that is to say the wave number, is 0.1 cm "1.

To acquire each of the spectra, 7 μΙ of the suspension formed of the pellet and the saline solution are deposited in the sensor. Spermatozoa are irradiated in the mid-infrared and their absorption spectrum is recorded after 6 minutes. 6.2.4. Data analysis

Spectra are subject to a quality control on various criteria before being selected for further analysis. Criteria considered for quality control include signal strength, interference, signal-to-noise ratio, and water content.

The average of the three acquired spectra is performed to obtain an averaged spectrum of the ejaculate.

The averaged spectrum is processed according to the procedure previously described in paragraph 6.1.3.

For all samples, the spectra are divided into two categories, the calibration spectra from the analysis of 70 ejaculates and the validation spectra from the analysis of the remaining eighteen ejaculates. Calibration spectra are used to construct the model to relate a variable to explain, here the TNR90brut, and explanatory variables that is to say an optimized selection of wave numbers of the spectrum. Once the model is optimized, the validation spectra are used to evaluate the predictive performance of the model.

The reduction of explanatory variables is performed by a genetic algorithm associated with a 10% cross-validation R-PLS. Once this reduction is achieved, the choice of the explanatory variables is optimized by the repetition of 100 linear regressions (RL), with cross validation on 10% of the initial population. A validation of the explanatory variables selected is carried out by integrating them into the law or linear equation used to predict the "unknown" samples. 6.2.5. Construction of models for determining the quality of a seed

The reference samples are split into a calibration subpopulation and a validation subpopulation. The learning is carried out on 4 / 5th of the ejaculates, the validation on the 5th remaining and for each of the sub-populations, one maximizes the number of ejaculates coming from different bulls while having a proportional representativity of the individuals in 3 classes of TNR90 defined as follows: TNR90 <40%, 40% <TNR90 <50% and TNR90> 50%. 6.2.5.1. Mathematical model

The mathematical model used is defined by the formula Y = β0 + Σ "= ι / 5, χ;", in which: Y is the TNR90 calculated for ejaculate; η (η> 7) is the number of wave numbers aj considered in the model;

Xj "is the normalized second derivative of the value of the absorption for the number of waves aj; βο is the offset at the origin; (l <j <n) is the weighting coefficient of the value of the second derivative normalized absorption Xj ", bounded by its standard error. 6.2.5.2. Examples of models

Three models are built from respectively 7, 9 or 20 wave numbers, minimizing the prediction error, RMSEP (Root-Mean-Square Error of Prediction), prediction according to the mean squared error ).

The spectral domains of the wavenumber chosen relate to the lipid absorption domain 3200-2800 cm -1, proteins (amide band B and 1440-1500 cm -1 domain) and DNA (1515 cm -1). 1490 cm -1, 1090 cm -1 and 970 cm -1). a) 7 wave number model

This model is detailed in Table 1, below, it presents a calculated coefficient of determination R2 (or "Multiple R-Squared" in English) of 0.4804 and a RMSEP of 4.8%.

Table 1

Distribution of residues, in minimum, maximum and quartiles:

Residual standard error: 0.05298 with 78 degrees of freedom

Adjusted coefficient of determination (Adjusted R2 or Adjusted R-Squared): 0.4337 F-statistic (F-value or Fisher's F-value): 10.3 over 78 degrees of freedom, P-value ( P value of the Fisher test): 4,455e-09 b) 9 wave number model

This 9 wave number model is detailed in Table 2, below. it has a calculated coefficient of determination R2 of 0.5884 and a RMSEP of 4.49%.

Table 2

Distribution of residues in minimum, maximum and quartiles:

Residual standard deviation: 0.04777 with 76 degrees of freedom

Adjusted coefficient of determination: 0.5397 F-statistic: 12.07 over 76 degrees of freedom, P-value: 1.325e-ll c) 20-wave model

This wave number model is detailed in Table 3, below. it has a calculated coefficient of determination R2 of 0.7785 and a RMSEP of 3.29%.

Table 3

Distribution of residues in minimum, maximum and quartiles:

Residual standard deviation: 0.03789 with 65 degrees of freedom Adjusted coefficient of determination: 0.7104 F-statistic: 11.42 out of 20 and 65 degrees of freedom, P-value: 2.375e-14 The relevance of this model to 20 wave numbers are illustrated in Figures 4A, 4B and 5.

FIGS. 4A, 4B and 5 show the correlation between the values of TNR predicted by the model and the known values for the samples used for the calibration (FIG. 4A), for the validation of the model (FIG. 4B) and for the set of samples (Figure 5).

As can be seen in Figure 6, for 86% of the samples, the model is accurate to less than 5 TNR points. 6.3. Example of embodiment of the invention

FIG. 1 is a schematic diagram illustrating the steps of an exemplary embodiment of a method for determining the quality of a seed of a vertebrate animal according to the invention.

In a step 110, the absorption spectrum of a pellet prepared, during a step 111, is measured by three times from two straws from a seed, using a spectrometer of model FT-IR SPID and with a sensor LS23 of DIAFIR (registered trademark).

In a variant of this particular embodiment of the invention, the absorption spectrum can be measured by transmission, by reflection or by ATR (acronym in English of "Attenuated Total Reflection").

The 3 measured spectra are then averaged to obtain an averaged spectrum (step 112).

In a step 130, a value of the second derivative of the absorption Xj "for n wave numbers aj (l <j <n) is determined from the averaged absorption spectrum of the seeds of the race of the animal, selected during a step 120.

Then, during a step 140, the 90-day non-return rate is calculated from the mathematical law.

where the coefficients 30 and 3j (l <j <n) are constants peculiar to the phenotype of the breed of the animal that produced the seed, using the values of the second derivatives of the absorption Xj "(je [i; n ]) determined in step 130.

In variants of this particular embodiment of the invention, it may be envisaged to calculate the 90-day non-return rate from the absorption values Xj for n wave numbers aj (l <j <n ) characteristics of the seeds of the race of the animal or using both absorption values and values of the second derivative of the absorption for the n wave numbers aj (l <j <n) characteristics seeds of the breed of the animal.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Thus, the method described in connection with an example is applicable for all races or species of vertebrate animals by adapting it to the phenotype of the race or species via the choice of characteristic wave numbers (explanatory variables). the quality of the seed of the race or species.

Claims (11)

1. A method for determining the quality of a seed of a vertebrate animal, characterized in that it comprises the following steps: measuring at least one absorption spectrum of a sample of said seed; selecting a number n, with n> 7, of wave numbers aj ϋε [ι; η]) characteristic of the seeds of the race or species of said animal; determination from said absorption spectrum or spectrums of a value of the absorption Xj and / or a value of the second derivative of the absorption xj "for each of the said n numbers of waves aj ϋε [ι; η]); - calculating a non-return rate Y at a predefined number of days from said absorption values Xj and / or the second derivative of the absorption X / 'previously determined. 2. Method for determining the quality of a seed according to claim 1, characterized in that said non-return rate Y is calculated according to the mathematical law Y = β0 + Σ "= ι ^; χ;", where Χ / 'ϋε [ι; η]) is the normalized second derivative of the absorption value for the number of waves aj and the weighting coefficients β0 and ϋε [ι; η]) are constants. 3. A method for determining the quality of a seed according to any one of claims 1 and 2, characterized in that the values of said weighting coefficients are obtained from a treatment of the measurements of the absorption spectra of a plurality of seed samples from a reference vertebrate population, whose non-return rates are known. 4. Method for determining the quality of a seed according to any one of claims 1 to 3, characterized in that during said measuring step, at least 2, preferably at least 3 absorption spectra of a sample of said seed is measured and in that said step of determining values of absorption and / or second derivatives of the absorption comprises a step of producing an average of said measured spectra from which said values are determined absorption and / or second derivatives of absorption. 5. Method for determining the quality of a seed according to any one of claims 1 to 4, characterized in that the number n of wave numbers aj ϋε [ΐ; η]) is greater than or equal to 9, preferably is greater than or equal to 20. 6. Method for determining the quality of a seed according to any one of claims 1 to 5, characterized in that said wave numbers are each representative of a molecule or a set of molecules selected from the group. comprising at least: lipids; carbohydrates; proteins; - nucleic acids; combining a lipid, carbohydrate, protein, or nucleic acid molecule with at least one other lipid, carbohydrate, protein, or nucleic acid molecule. 7. A method for determining the quality of a seed according to any one of claims 1 to 6, characterized in that said vertebrate is a bull and the rate of no return is a rate of no return to 90 days, said bull being from a breed selected from the group consisting of at least Abundance, Black-footed Bretonne, Brune, Jersiaise, Montbéliarde, Red Pie des Plaines, Prim'Holstein, Flemish Red, La Bleue from the north, the Normande, the Salers, the Tarentaise. 8. Method for determining the quality of a seed according to any one of claims 1 to 7, characterized in that said wave numbers aj ϋε [ι; η]) are chosen from the group comprising at least 955, 0 ± 0.1 cm 1, 963.1 ± 0.1 cm -1, 1012.1 ± 0.1 cm -1, 1036.6 ± 0.1 cm -1, 1095.8 ± 0.1 cm -1, 1124.3 ± 0.1 cm -1, 1136.6 ± 0.1 cm -1, 1365.1 ± 0.1 cm -1, 1383.5 ± 0.1 cm -1, 1428.4 ± 0, 1 cm -1, 1444.7 ± 0.1 cm -1, 1452.9 ± 0.1 cm -1, 1503.9 ± 0.1 cm -1, 1520.2 ± 0.1 cm -1, 2805. , 7 ± 0.1 cm -1, 2956.7 ± 0.1 cm -1, 2969.0 ± 0.1 cm -1, 2987.4 ± 0.1 cm -1, 3089.4 ± 0.1. cm -1, 3091.4 ± 0.1 cm -1. 9. Method for determining the quality of a seed according to any one of claims 1 to 8, characterized in that said step of measuring at least one absorption spectrum comprises a step of preparing said sample from said seed. 10. Method for determining the quality of a seed according to one of claims 1 to 9, characterized in that it comprises a step of comparing said non-return rate Y with a predetermined threshold, for selecting said seed. for reproduction purposes in the case where said non-return rate Y is greater than or equal to said predetermined threshold. 11. Method for determining the quality of a seed according to claim 10, characterized in that said threshold is greater than or equal to 0.4, preferably greater than or equal to 0.5, still more preferably greater than or equal to 0. 6.