Morphological and structural comparison between breed wools of first and second generation of Arkhar merino ×Ghezel with their parents using spectral analysis

Introduction: Arkharmerino sheep breed is a fine wool type. Crossbreeding can lead to combination of favorable characteristics from the breeds involved. The greatest part of the wool produced by the indigenous sheep breeds in Iran is used in the hand woven carpets. It is estimated that 5.1 million m² hand woven carpets is produced in Iran annually; therefore, the country needs 28 thousand tons of washed wool. Approximately 8 thousand tons of wool is imported as merino wool from Australia and New Zealand. Iranian wool is suitable for use in coarse-carpet industry, but it has some difficulties for use in the fine carpets. Fine carpet makers usually utilize imported wool, which has more uniformity of diameter. For finding suitable sheep breed to produce more uniform wool, we interest to Arkhar-Merino breed at University of Tabriz. The Kazakh Arkhar-Merino breed was produced at Kurmektinski experiment station of the Academy of Sciences of the Kazakh.  The purpose of research was to introduce a new breed of fine wool sheep which would combine the good production characteristics of the Merino with adaptability of local Arkhar. The breed is based on crossbreeding of wild Arkhar rams with ewes of the Novocaucasian Merino, Précoce and Rambouillet breeds. Crossbreeding between Iranian wool sheep and foreign wool breeds can lead to the production of a genetic combination with the better wool fibers. In order to evaluate fleece characteristics, wool samples of 451 yearlings of Arkharmerinos×Ghezel (ArGh) were collected by Mokhber et al. (2008). At first generation of ArGh, mean (± standard error) of fiber diameter, fiber diameter variability, staple length and percentage of true wool, medulla and kemp percentage were 27.10 ± 3.36 μ, 36.60 ± 7.84 %, 11.81 ± 4.06 cm, 91.31 ± 9.32%, 7.27 ± 6.90%, and 1.40 ± 3.03 %, respectively. At second generation of ArGh, the same traits were 26.33 ± 3.41μ, 34.64 ± 9.36 %, 10.15 ± 3.99 cm, and 95.41 ± 4.70 %, 3.39 ± 5.85 % and 2.01 ± 2.65 %, respectively.  The main aim of this work was to study the morphological and structural properties of breed wools of first and second generation of Arkharmerino ×Ghezel with breed Arkharmerino as a father's base and comparing with their parent's wool characteristics. The aim was to obtain information about crossbreeding of local fat tail rams with Arkhar-Merino ewes regarding the wool traits. Arkhamerino breed has been imported from Kazakhstan.
Material and methods: For this purpose, the wool fibers were sampled from the middle region of the sheep's body. The physical properties of the wool fibers, such as fiber diameter, staple length, Kemp fiber percentage and modulation fiber percentage were measured. For study the morphological properties of fibers, surface image of the fibers was prepared using a scanning electron microscope. In order to measure the structural properties of the fibers, which is one of the important factors in the production of textile products, the infrared spectrum of each fiber was obtained according to the relevant standards. The chemical structure (such as the components of the main and side chains, functional groups, various linking bonds, etc.) and the chain conformation in wool fiber play a crucial role in its mechanical, other physical, and service properties. The effect of wool breeding on the chemical structure and chain conformation of wool samples, which were from Ghezel sheep and Arkharmerino Sheep in first and second generations, were investigated by employing an FT-IR spectrometer (IR Affinity-1s ATR-FTIR, Shimadzu, Japan) in a spectral range from 500 to 4000 cm-2. The infrared spectra of the control sample of wool in Fig. 1 indicate that the strong peak with absorption band at 3399.5 cm-1 was assigned to the combined stretching vibrations of N-H and O-H (ν_N-H, ν_O-H), and the absorption bands at 2960.2 cm-1, 2930.0 cm-1, 2870.0 cm-1were assigned to the asymmetrical and symmetrical stretching vibrations of C-H in CH3 and -CH2- groups, respectively. Moreover, the strong peak with absorption band at 1639.8 cm-1was due to the stretching vibration of C=O from amide Ι (ν_{C = O}), which was essentially relative and indicative to the α-helix conformation of the main chains of wool (Wojciechowska et al. 2002). The medium peaks with absorption bands at 1540.1 cm-1 and 1239.9 cm-1 were attributed to the bending vibration of N-H (δ_N-H) from amide ΙΙ and the stretching vibration of C-N (δ_C-N) from amide ΙΙΙ, respectively. Moreover, the stretching vibration of C-N (δ_C-N) from amide ΙΙΙ was considered to be relative and indicative to the β-sheet conformation in wool fiber (Cai and Singh 1999). The peak at 1079.3 cm-1 was due to the vibration of sulfur-containing group of cystine in wool. Table 2 shows the average and standard deviation of absorption band of the functional groups in the wool fibers.
Results and discussion: The results showed that the fiber scales in crossbreed and Arkharmerino fibers have a telescopic and regular state that are different from the irregular structure of the Ghezel fiber scales. The measurement of structural properties showed that the wave number of amide, amine, hydroxyl and C-N bonds in the second generation was more similar to Arkharmerino and it can be concluded that in the second generation of Arkharmerino × Ghezel, genetic structure of fibers has the most similarity to Arkarmerino breed.
Conclusion: In general, the results show that the second-generation fibers of the Arkharmerino × Ghezel have a good structural and superficial quality for usingin textile products.