Upgrading The In vitro Dry Matter Degradability of Leaves Plus Sheaths of Wheat Straw by Using Physical Treatments

Abstract

Factorial experiments 3 x 2 x 2 in duplicate for each incubation time, were conducted to test the effect of dried leaves plus sheaths of wheat straw as a control and two soaking levels; soaking 1 (one litre of water and one kg of leaves plus sheaths of wheat straw) and soaking 2 (two litres of water and one kg of leaves plus sheaths of wheat straw), two soaking temperatures (20˚C and 60˚C) and two soaking times (2 and 16h) on invitro degradability of the leaves plus sheaths of wheat straws. About 0.5 g of dried and ground leaves plus sheaths of wheat straw samples were transferred into 50 ml plastic tubes. The leaves plus sheaths of wheat straw samples were incubated in buffered rumen fluid (RF) in water baths at 39oC for 46 and 92h. The RF was obtained from three fistulated sheep of Walsh Llyen breed. Average weight of 82kg each consuming daily 820g grass hay plus 410g a concentrate. The RF was withdrawn from the fistulated sheep after three hours of morning feeding, then filtered, through a cheese cloth, pooled and mixed with a buffer prepared according to the formula for synthetic saliva at a ratio of 1:4. After each incubation time, the un-degraded residues were collected, washed and dried to calculate the dry matter degradability (DMD) of each leaves plus sheaths of wheat straw for each treatment combination. The data were statistically analysed by using Minitab programme to study the main effects of soaking level and temperature and time of soaking and their interactions at each of the 2 incubation times. The effects were declared significant if (P<0.05). The higher soaking temperature (60°C) significantly (P<0.05) reduced DMD of leaves plus sheaths after 46h of incubation. Soaking time had a significant positive effect on DMD of leaves plus sheaths at 46h and 92h (P<0.001). Soaking ratios of 1:1 and 2:1 resulted in a considerable modification of cell wall composition and increased degradability at the two incubation times. However, significant improvements in DMD were obtained at 92h compared with 46h for leaves plus sheaths.