Studies on the skin and wool fibres of Barki sheep fed on protected lysine and methionine

摘要

Twenty-four adult Barki ewes (non-pregnant) aged 3-4 years with an average body weight of 28.95±1.37 kg was used in the study at Maryout Research Station, Desert Research Center. The present work was designed to evaluate the effect of feeding rumen protected amino acids, methionine or/and lysine on some wool follicle structures, skin amino acids as well as the wool fibres changes of Barki ewes. The study was carried out from September 2016 to February 2017. The histological study of the wool follicle in the skin of Barki ewes revealed that, it consisted mainly of outer and inner root sheaths. The increased values of the external diameter and the wall thickness of both primary and secondary wool follicles resulted in from the mixture have an ascending higher value in the lysine group followed by methionine which exhibited the greatest value while the internal diameter recorded a noticeable decrease in the methionine group followed by the other two groups. Histochemically, the general proteins were more abundant in the outer root sheath than in the inner root sheath of both primary and secondary wool follicles. In addition, all the experimental groups were exceeded the control group in the contents of general proteins especially in the methionine group which recorded the greatest amount of the proteins followed by the lysine group. The determination of the amino acid in the skin samples showed that, the addition of rumen protected amino acids (methionine or/and lysine) to the sheep nutrition recorded a variable increase in the content of some essential and non-essential amino acids in the skin of the experimental groups rather than the control group. The methionine group exhibited a significant increase in the content of all amino acids followed by the lysine group. The wool fibres produced from both primary and secondary wool follicles recorded an increase in their diameters rather than the control group especially in methionine group which recorded a significant increase in the fibre cross sectional area, fibre volume, fibre length growth rate, clean wool production, medulla thickness and the percentage of kemp fibres. Also, it recorded a significant decrease in crimp frequency and the percentage of the fine fibres rather than the control group.