UTILIZATION OF RICE STRAW FOR FEEDING RUMINANTS: 3- COMPARATIVE STUDIES BETWEEN CORN STALKS AND GREEN RICE STRAW SILAGE DURING SUMMER FEEDING

Two comparative studies between green corn stalks silage (CSS) and green rice straw silage (RSS) were conducted. The 1^st one was to evaluate the nutritional values of both kinds of silages using 6 adult rams in two digestion trials (3 in each).  The other comparative study was carried out in summer season using swing-over method to investigate productive performance of lactating buffaloes which fed rations containing either green corn stalks or rice straw silages.
Eight lactating buffaloes average 500-600 kg body weight at 2nd to 5th parities were used after 8 weeks of calving. Animals were fed three tested rations, the control (CR) represented traditional summer rations which composed of 53% concentrate feed mixture (CFM), 20% berseem hay (BH) 27% rice straw (RS) and the 1st tested ration (TR1) contained 42% CFM, 43% RSS and 15% BH, while the 2nd tested ration (TR2) was CFM, CSS and BH to supply 42, 43 and 15% of the daily DM intake, respectively. The impact of ensiled corn stalks and rice straw and their utilization for animal feeding per feddan was also investigated.
The two tested silages had a good fermentation quality as low values of pH, NH₃-N (%of total N) and normal concentration of VFA's. Corn stalks silage (CSS) had a higher nutritive values as TDN%, DE and DCP%, compared to green rice straw silage (RSS). Single crossbred of maize crop (Sc10) produced the highest silage yield / fedden being 5.13, 0.35, 0.23 and 3.03 ton/ feddan DM, CP, DCP and TDN, respectively. Corresponding values with rice straw (Sakha 104 variety) silage were 2.4, 0.14, 0.10 and 1.15 tan/ feddan.
No significant differences among tested rations for OM, EE and NFE digestibility, while the differences were significant (P<0.05) in CP and CF digestibility coefficients. TR2 had the highest values (P<0.05) in TDN and DE followed by TR1, while control ration showed the lowest values. On the contrary, CR showed significantly (P<0.05) the highest DCP value followed by TR1, while TR2 recorded the lowest value. No significant differences were observed for actual daily milk yield, while 7% FCM yield differed significantly (P<0.05) among the tested groups. In addition, there were significant differences in fat, lactose and total solids contents in milk, while no significant differences between groups on protein and SNF contents in milk. Buffaloes fed TR1 and TR2 recorded the best feed conversion compared with those fed CR. Daily feed cost decreased with including RSS and CSS in the 1^st and 2^nd tested rations by 14.44 and 6.95%, respectively. Also gross margin over feed cost for buffaloes fed TR1 and TR2 increased by 78.9 and 100.0 % compared with those fed CR. Economic efficiency improved by 34.10 and 35.23 % for groups fed rations containing RSS and CSS (TR1 and TR2, respectively) compared with feeding control ration. It could be concluded that inclusion of rice straw silage or corn stalks silage as a basal ration for lactating buffaloes in traditional summer rations led to reduce the amounts of CFM by about 20%, increased daily 7% FCM by 15.03 and 26.12% and improve economic efficiency, along with limiting the environmental pollution as a result of accumulation of rice straw or corn stalks in the fields or burning them.