| 9 health rams fitted with rumen fistula(Germany Merino sheep ♂ × Lintao local hybrid ♀ second generation) as experiment animals were chosen in this study, mainly fed with corn silage, the nutrition level was: ME 11.58 MJ/d and CP 14.73%. Three kinds of feed additives was chosen in test, EOC(Essential O il and Cobalt)、EO(Essential Oil)and Co(Cobalt)purchased from American Ralco company. Applying each additive was an independent test in which consisted of 3 adding levels, 0 g(control), 4 g and 7 g, each treatment was repeated three times, 9 repetitions in total. Latin square design was used in experiment.The ruminal degradation rates of corn silage nutrients(dry matter, crude protein and neutral detergent fiber and acid detergent fiber) were measured in first test to clarify the influence of different additives on nutrient degradability of corn silage, and initially identify the three add itives appropriate adding amount. According to the corn silage fiber structure changes before and after rumen microorganisms action to explore the influence of different additives on cell wall structures of corn silage fiber tissues(leaves and skin) in second test from macroscopic aspects, determining the appropriate adding amount further. In the third test, through measuring the rumen fermentation, we mainly understand the impact of different levels under different additives on sheep rumen environment.All results showed that:Test 1 Dry matter digestibily(DMD), neutral detergent fiber digestibility(NDFD), acid detergent fiber(ADFD) of corn silage were significantly higher in treatments of adding 4 g and 7 g EOC than control(P<0.05), improved 2.29% and 2.33%, 7.39% and 6.30%, 9.05% and 10.12%, respectively, but there was no significant difference between treatments of 4g and 7g(P>0.05). 4g EOC is beneficial to silage degradation; For the second additive EO, DMD, CPD, N DFD, ADFD of corn silage among different treatments was not different significantly(P>0.05), but there were increasing trend in 4g treatment for DMD and CPD, improved 0.65%, 2.58% than control respectively; Only adding Co, DMD and NDFD in treatment of 4g and 7g were increased by 4.51% and 3.01% than control(P<0.05), which indicated adding Co separately had significant effects on DMD, CPD, NDFD(P<0.05).Test 2 Observing the corn silage fiber structure changes before and after fermentation using stereoscopic microscope and scanning electron microscope, the results showed that, adding 7 g EOC was most effective on silage corn fiber degradation. The silage corn fiber structure digested to a lesser extent when no adding EOC, EO and Co; The corn silage fiber structure has different extent degradation when adding 4g EOC, CO and Co.Silage leaf surface wax layer is destroyed, all cuticle and leaf were digested and destroyed, only leaving palisade, spongy tissue, and vein structure entirely; While adding 7g EOC, EO and Co, the corn silage was completely digested only parallel veins mesh framework was left.Test 3 The p H of sheep rumen fluid was significantly reduced when adding EOC and EO(P <0.05), but there were no significant effect on it when adding Co(P >0.05); Adding EOC and EO had no s ignificant effect to concentration of NH3-N in rumen fluid(P>0.05), but with the adding amount there was a downward trend; The concentration of NH3-N had a significant change when adding Co, it was increased significantly in 7g treatment(P< 0.05). Different doses of the EOC and Co had significant effects on acetic acid and total volatile fatty acids(TVFA)(P<0.05), acetic acid was highest in 4g treatment, while TVFA were significantly lower in 7g than control and 4g(P<0.05); but there were no significant effect on other indexes such as propionic acid, butyric acid and ethylene / propylene(P>0.05). O nly adding different doses of EO had no significant impact on all of indexes in sheep rumen fluid(P>0.05);... |
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