Manuel Antonio Chagas Jacinto

Características anátomo-estruturais da pele de ovinos (Ovis áries L.) lanados e deslanados, relacionadas com o aspecto físico-mecânico do couro

Instituto de Pesquisas Tecnologicasdo Estado de Sao Paulo Centro Tecnologico de Courose Calcados, Franca, SP

Proposition of classification models for the direct evaluation of the quality of cattle and sheep leathers using laser-induced breakdown spectroscopy (LIBS) analysis

This study proposes classification models for the prediction of the quality parameters of cattle and sheep leathers. In total, 375 leather samples were directly analyzed by laser-induced breakdown spectroscopy (LIBS). Exploratory analysis using principal component analysis (PCA) and classification models employing K-nearest neighbor (KNN), soft independent modeling of class analogy (SIMCA), and partial least squares – discriminant analysis (PLS-DA) were the chemometric tools used in the multivariate analysis. The goal was to classify the leather samples according to their quality. The calculated models have satisfactory results with correct prediction percentages ranging from 75.2 (for SIMCA) to 80.5 (for PLS-DA) for the calibration dataset and from 71.6 (for SIMCA) to 80.9 (for KNN) for the validation samples. The proposed method can be used for preliminary leather quality inspection without chemical residues generation.

Influence of genotype on the quality of sheep leather

The objective of this study was to evaluate the influence of crossings between sheep breeds on the intrinsic quality of leather. It was used the skins of 36 lambs (18 females and 18 males), resulting from crosses between ewes of a native breed from the Brazilian state of Mato Grosso do Sul and rams of the same native breed as well as the Texel and Santa Ines genetic groups. The animals were raised in confinement until slaughter weight, from 28 to 32 kg. After slaughter, samples were taken from the skins for histological analysis. The skins were tanned with chromium, retanned and greased. It was taken from the leather samples for electromicrographs and for tests for tensile and tear strength (intrinsic quality). Morphological aspects from the skin as well as from the leather help to understand the results found and they evidence that breeds or crossings among breeds interfere in the intrinsic quality of leather and skin of sheep.

Histologia da pele da carpa prateada (Hypophtalmichthys molitrix) e testes de resistência do couro

The objectives of this trial were to analyze the skin histology and to evaluate the influence of tanning technique and the direction removal of samples on skin quality of silver-plated carp (Hypophtalmichthys molitrix). Twenty-three fishes were sacrificed and the skin was removed for tanning. Samples of three fishes were settled in formol 10% and, after inclusion in paraffin, the samples were cut with approximately 5 mm of thickness and colored by the hematoxylin-eosin technique (HE). After skin tanning, the samples were removed for resistance tests. The tests were done with EMIC dynamometer, at removal speed of 100 ± 20 mm/mm, in a climatized environment (23oC) and 50% air relative humidity for 24-h period. The skins tanned with chromium salts showed greater resistance to tensile strenght (16.96 N/mm2), elongation (51.49%) and progressive tearing (16.75 N/mm) than those tanned without chromium salts (tensile strenght = 9.12 N/mm2, elongation = 17.48% and 11.36 progressive tearing = N/mm). No effect of direction removal of samples on tensile strenght, elongation, rupture load, progressive tearing, maximum force, and force load was observed. The tanning technique (with or without chromium salts) affect the resistance of the silver-plated carp skin. The technique with chromium salts results in bigger resistance to leather.

Thermoregulation of male sheep of indigenous or exotic breeds in a tropical environment

Climate change has intensified the frequency of heat waves in the world, thereby exposing farm animals to stressful conditions. For better productive performance it is important to identify the most resilient genotypes. Thus, our objective was to evaluate the thermoregulatory responses of rams of tropical indigenous (Morada Nova and Santa Inês) and exotic breeds (Dorper and Texel), by monitoring the environmental and physiological indicators related to heat tolerance. The experiment was carried out in a tropical climate region (Cwa), in Brazil, for twelve months, which comprised spring, summer, autumn and winter. Thirty-three rams were divided into groups: Morada Nova (MN; n=8, red-coat), Santa Inês (SI; n=9, black-coat), Dorper (DO; n=8, white-coat) and Texel (TX; n=8, white-coat). The microclimatic variables were monitored, and the THI and BGHI comfort indices were calculated. Coat thickness and body surface temperatures were measured monthly, and serum triiodothyronine-T3 measurements and complete blood tests were performed. The physiological variables were evaluated every fifteen days and skin micro-biopsies were performed in the summer and winter for histological evaluation. During the warmer seasons, the THI and BGHI reached values that indicated thermal discomfort. TX showed higher coat thickness throughout the year, increased physiological variables related to thermolysis, and reduced T3 (P < 0.05). The internal temperature was permanently lower in the MN, SI and DO (P < 0.05). The body surface temperatures were affected by the coat characteristics and wool length. Hematological parameters varied in the seasons with the highest thermal conditions (P < 0.05). The MN showed larger sweat glands, while the area occupied by the sweat glands was higher in the SI. The DO showed higher hair density in the summer and winter (P < 0.05). The results indicated that the MN, SI and DO breeds overcome the thermal challenge more easily throughout the seasons due to specific adaptive morphological and physiological characteristics.

Potential of near-infrared spectroscopy for quality evaluation of cattle leather

Models using near-infrared spectroscopy (NIRS) were constructed based on physical-mechanical tests to determine the quality of cattle leather. The following official parameters were used, considering the industry requirements: tensile strength (TS), percentage elongation (%E), tear strength (TT), and double hole tear strength (DHS). Classification models were constructed with the use of k-nearest neighbor (kNN), soft independent modeling of class analogy (SIMCA), and partial least squares-discriminant analysis (PLS-DA). The evaluated figures of merit, accuracy, sensitivity, and specificity presented results between 85% and 93%, and the false alarm rates from 9% to 14%. The model with lowest validation percentage (92%) was kNN, and the highest was PLS-DA (100%). For TS, lower values were obtained, from 52% for kNN and 74% for SIMCA. The other parameters %E, TT, and DHS presented hit rates between 87 and 100%. The abilities of the models were similar, showing they can be used to predict the quality of cattle leather.