Bovine Demodicosis: Leather from the Raw Material to the Finished Product

摘要

Demodex bovis mites and associated bacteria produced lesions ranging from 25 to 3618 per hide. Infected hides were compared to non-infected ones, from the raw material to the finished product. Infected hides showed the following defects: (1) Severely infected hides were green-graded as rejects. (2) The curing time was longer than non-infected ones. (3) The rate of water absorption was reduced by more than 50% (4) Liming resulted in dark blue precipitate on the lesions due to uneven distribution of the sulphide. (5) Scudding was very difficult. (6) De liming and pickling resulted in circular white blemishes on the grain surface. (7) Slipping-off of the grain surface over severely infected areas. (8) The degree of plumping was only 12-22%. (9) Splitting was very difficult, and when split, holes and cavities were evident. (10) Shaving resulted in detachment of all the lesions on the flesh side leaving numerous pits and holes. (11) The aesthetic appeal and cutting areas of the leather were markedly reduced. (12) Severely infected hides were difficult to finish, required more effort in buffing and utilized more dye without producing a drastic improvement in acceptability, and the grain surface was unsightly, uneven, full of elevations and depressions. Leather sections revealed ragged cavities with no definite boundaries. The fibres round those cavities were distorted, thinner than normal and compressed. The grain of the leather showed many small shallow depressions and separation of the grain surface from the corium in areas with large lesions. Severely affected leather showed complete damage and distortion of both the grain surface and corium. Bovine demodicosis infected hides resulted in a significant reduction at (p<0.01) in the cure-index, tensile strength, tearing load, percentage elongation, correlation coefficient of tensile strength versus tearing load, apparent density, flexing endurance, distension at grain crack, hide substance, moisture, fat and ash contents compared to non-infected ones. However, the distension at grain burst of infected specimens showed a significant reduction at (p<0.05) over non-infected ones.