Study On Grazing And Housefeeding Method Of Sheep In Songnen Grasslands

In the grassland grazing system,herbivores had a strong influence on plants,and there were constraints of plants on livestock production.In order to deep understanding the grassland ecosystem function,maintenance of ecological processes and productive practice,it was importantthat conducted the research of livestock in grassland.The study of grazing livestock feeding was a weakness of the grazing system of Songnen grassland in winter.So,lack of winter livestock house feeding methods restricts livestock production practice.Based on the necessity of grassland grazing theoretical research,and the urgency of guiding grassland production practice,the main experimental contents as follows.The effect of grazing intensity and rest grazing system of sheep on the grassland vegetation and soil.Firstly,based on the selective feeding of sheep,the spatio-temporal characteristics of foraging behavior of sheep were tested.Secondly,from the perspective of the nutrition balance between grass nutrition supply and demand forlivestock,the nutrition balance of energy,protein and mineral elements supply and demand of sheep were carried out.Finally,from the view of production,the performance of sheep under different grazing intensities was analyzed.In winter,theroughage supply technologyof sheep was carried out in winter.The effect of Suaeda glaucaon the physiological and biochemical characteristic of sheep blood was Reserarched.The feeds formulation of sheep was carried out in winter.The principal results are as follows.(1)There was no significant influenceof grazing intensity on the grassland biomass.There were significant effects of grazing intensity on the eating forage of sheep,and there was a reduction for grazing.Moderate grazing disturbance could not maintain higher plant diversity in Songnen grassland,especially in a dry year.There was no significant influence of grazing intensity on the density and water content of soil.There was the tendency to make the soil compact by sheep with long term heavy grazing.There was no significant effect of grazing intensity on total nitrogen,total phosphorus and total potassium content of soil.There was positively responded of soil available nutrients content to grazing intensity.Grazing could lead to the decrease of available nitrogen of soil in the short term.Available phosphorus in grassland surface soil was sensitive to grazing intensity,the content of available phosphorus in surface soil decreased with the increase of grazing intensity.There was the effect of grazing intensity on available potassium of in deep soil.With the increase of grazing intensity,the content of soil organic matter decreased.Furthermore,the influence of grazing intensity on soil organic matter decreased with the increase of soil depth.(2)Long term continuous grazing can not maintain the maximum grassland productivity in Songnen grassland.Moderate grazing was beneficial to increase grassland productivity.It was really important that rest grazing for grassland survival and the maintenance of plant diversity during spring and autumn.The suitable grazing system was 4 sheep/hm~2 and rest grazing during Spring or Autumn for maintaining high grass standing and plant diversity in Songnen grassland.There was no any superiority that the seasonal dynamic grazing intensity of rest grazing system compared to continuous and stable grazing intensity of rest grazing system.The grazing system had no effect on total nitrogen and total phosphorus in grassland soil.Four sheep/hm~2 or rest grazing were more conducive to the maintenance of total potassium content in soil.Continuous stable grazing stress could significantly reduce available nitrogen in surface soil.Seasonal dynamics grazing pressure or rest grazing could significantly reduce available nitrogen in middle deepth soil.The contents of available phosphorus and available potassium in grassland surface soil were sensitive to grazing system.There was no significant effect of rest grazing system on the content of available P and K in soil.The organic matter content of 0-20 cm deepth soil responded positively to the grazing system.(3)The spatial distribution characteristics of sheep foraging path were closely related to the patch distribution of grassland plant communities.The spatial distribution pattern of sheep feeding trajectory was clustering model.There was repeated visits phenomenon of sheep to the same plant community,and with the extension of grazing time,the area of repeated visits increased gradually.Grazing intensity had a significant effect on repeated visits to specific plant communities.As grazing intensity increases,more sites of repeated visits to specific plant communities were repeated.The utilization of grassland space by sheep was an extended utilization model.Different grazing intensities hadaltered utilization patterns of sheep on grassland.The expanding pattern of sheep to grassland was decreasing and then increasing with moderate grazing intensity(4 sheep/hm~2).The expanding pattern of sheep to grassland space is gradually increasing with high grazing intensity(6sheep/hm~2).With the continuous grazing time,the utilization of grassland space increased gradually.Characteristics of utilization grassland space by sheep was locality.In order to determine the proper utilization of grassland by livestock should be taken into account the selective feeding of livestock.The appropriate utilization rate of Songnen grassland should be based on the number of livestock eating grass.(4)There was no significant effect of grazing intensityon the metabolizable energyintake by sheep.The metabolic energy intake of grazing sheep showed a downward trend in the grazing season.The metabolizable energy intake by sheep was lower than that of sheep requirement,the manual supplementation of metabolizable energy to sheep was needed in July,August and September.Grazing intensity affected the crude protein daily intake by sheep,moderate grazing wasadvantageous to protein intake by sheep.The daily intake of crude protein by sheep showed a single peak curve.The crud protein intake by sheep was lower than that of sheep requirement,the manual supplementation of crud proteinto sheep was needed in June,July and September.K,Na,Mg and Fe in herbage could meet the demand of sheep.But,the contents of Ca,Mn and Zn in herbage were lower than that the demands by sheep,the manual supplementation of Ca,Mn and Zn to sheep was needed.There was significant influence of grazing intensity on the performance of sheep.Moderate grazing was beneficial for sheep to gain high daily gain.There were higher lambing rate and reproductive survival rate of sheep in moderate grazing compared to high grazing intensity.There was a negative impact of high grazing intensityon lamb performance.(5)Our results suggested that dietary roughage mixes could promote forage intake and improve growth performance of ewes during winter.There was a positive effect of dietary roughage mixes on the intake of low-quality roughage.Based on the observations of roughage intake and animal performance,feeding roughage mixtures comprised by a diverse roughage mixturetolivestock represents one method for utilizing roughage resources in livestock production during winter in the pastoral-farming area of northeastern China.The blood physiological and biochemical characteristics of sheep could be affected by feeding Suaeda glauca.The addition of Suaeda glauca changed the concentration of Na,Cl,Cd and ALT in the blood of sheep.The increase of Cd concentration in blood of sheep should be paid enough attention to the addition of Suaeda glauca with Leymus chinensis.When exploitating and utilizingthe halophytes to forage resources for ruminants,the security of mineral elements in halophytes to animals must give a deep appraisal.Furthermore,the security of mineral elements in halophytes transmitted from the food chain.Based on the above research results,the utilization model of sheep grazing system in Songnen grassland as follows.The suitable grazing system was continuous grazing,and according to the actual situation,rest grazing in spring or autumn.The suitable grazing intensity was 4 sheep/hm~2(including lambs).The grassland utilization were that start herding at middle or late in March.According to the actual situation,the mode of grazing or grazing could be adopted from mid March to mid May.Grazing+feeding mode(half grazing+half feeding)could be adopted to avoid forage shortage by sheep.The grazing system of“go out early and come back at dusk”was used for grazing from mid May to mid September.In the meantime,Sheep should be supplemented with mineral elements such as Ca,Zn,and Mn.Mowing was done in mid September,the stubble height was about 4-8 cm.The hay would be used to feed sheep in winter.Sheep were grazed on stubble grassland,and energy and protein should supply to sheep from end September to October.Sheep should be given housefeeding after snow covering grassland.The variety of roughage should be provided to sheep in winter.The ideal feeds formula forsheep was corn 11.72%,soybean meal 4.01%,salt 0.10%,corn stalk 30%and Leymus chinensis 54.17%during winter in the pastoral-farming area of northeastern China.