Method for determining the amount of at least some of the fatty acids contained in various biological materials of the same animal raised for meat production, from a database in which the fatty acid compositions or profiles have been determined beforehand, for a reference material coming from the same type of animal, determined by gas phase chromatography, then measuring and recording the corresponding infrared absorption spectra or corresponding Raman scattering, which method comprises the following steps: a/a calibration equation corresponding to the determination of a fatty acid or a sum of fatty acids by a spectroscopic method is determined for a sample of this reference material by a mathematic model; b/ the use of said calibration equation of the preceding step is validated, in view of its use with new samples to be analyzed, since for a series of so-called "validation" samples of the same nature as the biological reference material, the correlation coefficient r 2 between the fatty acid content considered or the sum of fatty acids obtained by gas phase chromatography and spectroscopy, is at least equal to 0.7; c/a new sample to be analyzed, of the same nature as the reference material, is subjected to light radiation to obtain the absorption spectrum, and the previously validated calibration equation is used to deduce the profile, i.e., the so called "major" fatty acid content, namely those with a correlation coefficient r 2 at least equal to 0.7; characterized by the fact that it also comprises at least one of the following steps: d/ the profile, i.e., the so-called "minor" fatty acid content, namely those whose coefficient r 2 is less than 0.7, is determined from the profile of "major" fatty acids as determined in the previous step, using statistical prediction equations with a correlation coefficient r 2 at least greater than correlation coefficient r 2 determined between the so-called "minor" fatty acids, measured by spectroscopy and the values obtained by gas phase chromatography, or using statistical prediction equations with a correlation coefficient at least equal to 0.7, obtained with the gas phase chromatography method; e/ the fatty acid content of at least one other material from the same animal is determined, from the profiles obtained in steps c/ and/or d/, by means of statistical prediction equations with a correlation coefficient at least equal to 0.7, obtained with the gas phase chromatography method. a/a calibration equation corresponding to the determination of a fatty acid or a sum of fatty acids by a spectroscopic method is determined for a sample of this reference material by a mathematic model; b/ the use of said calibration equation of the preceding step is validated, in view of its use with new samples to be analyzed, since for a series of so-called "validation" samples of the same nature as the biological reference material, the correlation coefficient r 2 between the fatty acid content considered or the sum of fatty acids obtained by gas phase chromatography and spectroscopy, is at least equal to 0.7; c/a new sample to be analyzed, of the same nature as the reference material, is subjected to light radiation to obtain the absorption spectrum, and the previously validated calibration equation is used to deduce the profile, i.e., the so called "major" fatty acid content, namely those with a correlation coefficient r 2 at least equal to 0.7; characterized by the fact that it also comprises at least one of the following steps: d/ the profile, i.e., the so-called "minor" fatty acid content, namely those whose coefficient r 2 is less than 0.7, is determined from the profile of "major" fatty acids as determined in the previous step, using statistical prediction equations with a correlation coefficient r 2 at least greater than correlation coefficient r 2 determined between the so-called "minor" fatty acids, measured by spectroscopy and the values obtained by gas phase chromatography, or using statistical prediction equations with a correlation coefficient at least equal to 0.7, obtained with the gas phase chromatography method; e/ the fatty acid content of at least one other material from the same animal is determined, from the profiles obtained in steps c/ and/or d/, by means of statistical prediction equations with a correlation coefficient at least equal to 0.7, obtained with the gas phase chromatography method.