Processing And Utilization Mode Of Stipa Steppe Grass And Related Mechanism Involved

Processing and utilization mode of Stipa steppe grass and its related mechanism was discussed in this study. Firstly, the changerule of the grass yield and nutrition content of Stipa steppe in different harvest time was studied to in order to determine the optimal harvest time of Stipa steppe to harvest excellent quality natural grass.Then on this basis, L9(43)orthogonal experiment was designed according to 4 factors influenced the forming of Stipa grass pellets in the pellets process-that is raw material grinding size,pellets diameter, raw material moistureand bentoniteadditive amount. The formability, nutrient content, in vitro dry matter digestibility and grazing and ruminating behavior of sheep of Stipa grass pellets was assessed comprehensively to determine theoptimalprocessing technique of Stipa grass pellets.The effect of feeding Stipa grass product of different shapes(grass block, grass particles, grass meal and hay without any treatment) on grazing and ruminating behavior, characteristic index of nutrient digestibility and metabolism (rumen fluid pH, total nitrogen,ammoniacal nitrogen,urea nitrogen,protein nitrogen,volatile fatty acids andthe particle size distribution of rumen chyme) of sheep was observedas to reveal the change mechanism of Stipa grass product in feeding process and provide theoretical direction and data support for determining the optimal feeding Stipa grass product shape and qualityto further optimize livestock management.This experiment used the design of single factor, double factors, orthogonal testexperiment designand combined the analysis method of normalization method,range method, analysis of variance,the optimal sequence correlation analysis,correspondence analysis, fuzzy evaluation.The results were as follows:(1) Comprehensively considering grass yield and relative feed value of Stipa steppe, the optimal harvest time of Stipa steppe is early stage of the heading in which hay yield(2183.36kg·hm-2) and relative feed value(69.44) of grass are relatively higher.(2) The optimum processing technique of Stipa grass pellets is grinding particle size 6mm, pellets diameter 6mm,raw material moisture content 16%-18% and bentonite additive amount 3%.The sensory quality, forming rate, density, hardness, nutritive value, in vitro dry matter digestibility and grazing and ruminating behavior of Stipa grass pellets which was produced in this condition were best.(3) After the grass of Stipa was formed tograss pellet, The intake rate and apparent digestibility of dry matter, crude protein, neutral detergent fiber and acid detergent fiber was 87.33±1.53%、66.72±1.49%、70.96±2.17%、61.43±1.53%、83.25±1.07%, respectively. The nitrogen digestibility and nitrogen deposition rate of Stipa grass pellet was 71.03±0.02% and 51.16±0.04%.There is significant difference with hay, grass meal and grass block (P<0.05).(4) Under drylot feeding condition, total average grazing time and total average ruminating time per day were 343.45±25.07 min and 564.61±11.73 min, respectively. Total chewing food pellet numbers were 534.96±35.41. Total ruminating cycle numbers were 24±1.05 with duration of each ruminant cycle of 23.53±1.20 min, and food pellet-inverse number in each ruminant cycle of 22.29±1.10. Total food pellet chewing times, the interval time between two food pellet swallowed chewing times of each food pellet and chewing time of each food pellet were 49248.42±3706.14,8.00±0.52 second, 92.06±0.83 and 55.34±1.76 second, respectively.The optimal shape of Stipa products for sheep was pellet whose palatability was best.(5) By studying the influence of Stipa grass products on the rumen environment of sheep, the pH value of rumen fluid of grass pellet treatment markedly decrease. The concentration of ammoniacal nitrogen, urea nitrogen and protein nitrogen increased markedly in pellet treatment. The total volatile fatty acids content of grass pellet and block treatment was higher than hay and grass meal.Stipa grass pellet2-3 mm range of chyme particle proportion was 14.70%, significantly higher than that of hay and grass meal treatment (P<0.05).Stipa grass pellet 0.1-1.0mm range of chyme particle proportion was 78.80%, significantly lower than that of hay and grass meal treatment (P<0.05).Stipa grass pellet<0.1mm range of chyme particle proportion was 6.24%, significantly higher than that of hay, grass meal and block treatment(P<0.05).In conclusion, the grass of Stipa steppe was harvested in the early stage of the heading. The feed value, grazing and ruminating behavior, characteristic index of nutrient digestibility and metabolism of Stipa grass pellets which processed in the optimum processing technique (grinding particle size 6mm, pellets diameter 6mm,raw material moisture content 16%～18% and bentonite additive amount 3%) were better.Stipa grass pellet was the optimal feeding and utilizing shape.