研究目的
Evaluating the possible effects on the hair of cats submitted to three different diets with 6.5, 11.3 and 16.6 g/kg of methionine + cystine supplementation using FT-Raman spectroscopy and comparing the results obtained to a mechanical parameter.
研究成果
The employment of FT-Raman spectroscopy showed to be a helpful technique to evaluate cystine in cat hair submitted to an intake of methionine + cystine diet supplementation in different quantities, also providing information on secondary protein conformation of keratin. Studies on the metabolic processes under the intake of sulfur amino acids in the cat feed using Raman spectroscopy are needed to evaluate the pathway of amino acids supplementation.
研究不足
The study did not measure other metabolic compounds. The presence of iron and cooper, there is a replacement of cysteine by homocysteine in keratin culminating with hair damage in humans. The study was not able to determine the metabolic priorities in the body of the cats under the intake of sulfur amino acids.
1：Experimental Design and Method Selection:
Domestic cats were submitted to an experimental diet with different levels of methionine and cysteine. Their hair was evaluated by using FT-Raman spectroscopy on the first and on the last day of the diets. The results were compared with tensile rupture measurements.
2：Sample Selection and Data Sources:
Eighteen cats were distributed randomly, males and females, among the three treatments resulting in six different cats submitted to each treatment. The treatments were isoenergetic experimental diets, named as T1, T2 and T3, containing
3：5, 3 and 0 g/kg (amino acids per dry matter) of methionine + cystine, respectively. List of Experimental Equipment and Materials:
FT-Raman spectrometer (Bruker, Vertex 70v-RAM II, Germany) equipped with Nd:YAG laser with excitation line 1064 nm, set up at 500 mW. The signal was detected by liquid nitrogen cooled Ge diode.
4：Experimental Procedures and Operational Workflow:
Each hair cat portion was positioned over a mirror parallel to the excitation laser incidence plane. The Raman spectra were collected with FT-Raman spectrometer. Each spectrum is an average of 300 scans with 4 cm-1 of resolution acquired between 4000 – 400 cm-
5：All the spectra were baseline corrected and normalized at 2930 cm-1 band intensity. Data Analysis Methods:
Principal components analysis was performed using the ‘prcomp’ function proposed in the reference [17]. Besides the area band of νS-S was obtained by integration and α-helix using the area provided by Gaussian fitting.
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