Effect of ensiling and level of supplementation with concentrates on the voluntary intake and digestibility of wheat straw by Arabi lambs

An experiment was conducted with 24 Arabi lambs to investigate the possibility to increase the utilization of wheat straw by ensiling with urea at rate of 1.5 % as a nitrogen source and to get the advantage of the additional digestion caused by the released ammonia, and molasses at rate of 10 % to encourage the fermentation responsible for silage making. Straw silage (ES) was compared with wheat straw (TS) containing both additives with the same rates, without ensiling. Both ES and TS were fed with two levels of concentrates. The straw silage was of medium quality with accepted palatability by lambs. Results of the experiment showed that ensiling had no effect on the total dry matter intake (TDMI) and straw dry matter intake (SDMI), but the digestible dry matter intake (DDMI) was improved significantly (P<0.05). Doubling the concentrate level increased TDMI and DDMI significantly (P<0.01). Digestibility trial pointed out that the ensiling improved dry matter digestibility (DMD) and its component significantly (P<0.01), except that of ether extract (EED) which was decreased significantly (P<0.01) as a result of doubling the concentrate level. pH of rumen fluid showed an expected values according to time of sampling and determinations. Results of this experiment also showed that ensiling wheat straw with urea and molasses could be beneficial procedure due to the improvement of both crude protein (CPD) and crude fiber (CFD) digestibilities and that the ensiling enhanced the utilization of urea N, the later needs more specific investigations. Introduction Since large quantities of straws are available as a by products of cereals, it must be efficiently introduced in feeding. Straws was known to be of low quality roughage due to their high fibre and low protein contents, so that many experiments were done to investigate the possibility of improving the nutritive value by the addition of urea or other like materials to support the nitrogen content, however, little were done to improve this low nutritive value by ensiling, unless some separated studies on the fermented straws with some additives such as NaOH and other bases, urea and molasses and some green roughage . Elpat ,Evskii and zharkov in on old study (1961) found that ensiling of oat straw with 1.74% urea increased crude protein content from 5.2 to 10.1% and reduced the nitrogen free extract content from 45.1 to 36.2 %, the same finding was stated by shultz et. al. (1974) in ryegrass straw. Salih (1983) conducted an experiment with ensiled wheat straw, the results reported a significant improvement in crude protein digestibility. Materials and Methods Twenty four Arabi lambs with an initial weight of about 23 kg were used. The lambs were allotted randomly into four groups of six lambs each according to body weight. Individual