| This research was aimed to study the effects of different varieties, harvest time, parts and drying method on the nutritive value of rape straw and also had a preliminary study on multi-relationship in physichemical properties of rape straw. Which was in order to provide a theoretical basis on rational utilization for green fodder of rape straw.Experiment 1: This experiment was conducted to study the effects of physichemical properties and nutritive value of sixteen kinds of rape straws. The results showed as follows:(1) Chemical composition contents had little differences in common varieties and double low varieties of rape straws(P>0.05), but Pith tissue area, vascular bundles area in common varieties was slightly larger than these in double low varieties; cortex cell thickness in common varieties was slightly less than these in double low varieties, while pith tissue area/stem crosscutting area, vascular bundles area/stem crosscutting area and cortex cell thickness/ stem diameter had little differences in common varieties and double low varieties of rape straws;(2)from the perspective of the physical characteristics of the rape straws, epidermis cell thickness/stem diameter varied from 0.20% to 0.32%, cortex cell thickness/ stem diameter vary from 2.69% to 4.76%, vascular bundles area/stem crosscutting area varied from 2.98% to 7.78%, pith tissue area/stem crosscutting area varied from 81.73% to 89.02%;shearing force was 11.23 to 18.72 kg, linear density was 14.75 to 21.73 mg/mm, shearing force/linear density was 0.64 to 1.25 kg/mg?mm-1; form the perspective of the chemical composition contents of the rape straws, dry matter(DM) varied from 93.47% to 97.06%, crude protein(CP) varied from 2.72% to 6.62%, ether extract(EE) varied from 0.49% to 3.69%, crude ash(Ash) varied from 5.74% to 9.83%,neutral detergent fiber(NDF) varied from 59.79% to 69.33%, acid detergent fiber(ADF) varied from 40.68% to 49.19%,glucosinolate content varied from 0 to 204.2 ?g/kg; there is great differences in vascular bundles area, pith tissue area, vascular bundles area/stem crosscutting area, shearing force/linear density, CP, EE and glucosinolate content in sixteen kinds of rape straws; while other items had little differences in sixteen kinds of rape straws;(3) 14M049 had optimal feeding value in those sixteen kinds of rape straws according to RFV results.Experiment 2: This experiment was conducted to study the effects of different harvest time on rapeseed yield and nutritive value quality of rape straws. Rape straw had been collected at green mature stage, earlier yellow mature stage, later yellow mature stage and full ripe stage respectively.1000-grain weight, Oil content, Oil content in 1000-grain weight was used to represent rape seed harvest yield and the nutritive value of the rape straws were evaluated by the method of feed proximate analysis and relative feed value(RFV). The results showed as follows:(1)1000-grain weight of rapeseed showed an increasing tendency with time passing by, there was a significant differences in 1000-grain weight of rapeseed between the full ripe stage and other harvest time(P<0.01); oil content and the oil content in 1000-grain weight of rape seed increased firstly and then decreased, there was a significant differences between the later yellow mature stage and other harvest time(P<0.01);(3)DM content and EE content of rape straw increased firstly and then decreased, and the discrepancies in each harvest time reached notable and very notable level(P>0.05 or 0.01);CP content of rape straws was appeared downward trend in volatility, the minimum value had been reached at the full ripe stage. Ash, NDF and ADF content of rape straws both decreased firstly and then increased, the minimum value had been reached at the later yellow mature stage(P<0.05 or 0.01);(3)RFV of rape straws increased firstly then decreased in the four harvest times, there was a significant higher in RFV between later yellow mature stage and other harvest times(P<0.01),and the RFV of rape straws in green mature stage was extremely significant lower than other harvest times(P<0.01). The results indicated that rape harvests in later yellow mature stage is the best to rapeseed yield and quality of rape straw.Experiment 3: This experiment was conducted to study the effects of different parts on physichemical properties and nutritive value of rape straw. Physical structure, morphological indexes, nutritional contents and RFV of different parts(apex~40 cm above base, 40 cm above base~20 cm above base, 20 cm above base~ base) of rape straw were studied respectively. The results showed as follows: the epidermis cell thickness/stem diameter, the cortex cell thickness/ stem diameter, the vascular bundles area/stem crosscutting area in forepart, middle and posterior segment of rape straws showed a downward trend; the pith tissue area/stem cross cutting area, shearing force, linear density and shearing force/linear density showed a rise trend from forepart to posterior segment of rape straw(P<0.05 or 0.01), DM content in forepart was significantly higher than that in the middle and posterior segment(P<0.01),the CP content(P<0.05)and the Ash content(P<0.01)were forepart segment>posterior segment> middle segment, the EE content in the forepart, middle and posterior segment showed a downward trend(P<0.01),the NDF and ADF content were forepart segment>posterior segment> middle segment(P<0.01). RFV in forepart segment is better than that in posterior and middle segments.Experiment 4: This experiment was conducted to study the effects of oven-dry and sun-dry on physicochemical properties and nutritive value of rape straw. The results showed as follows: shearing force of the oven-dry rape straw was significantly lower than the sun-dry rape straw(P<0.01); CP and Ash content of the oven-dry rape straw was significantly higher than the sun-dry rape straw(P<0.01); ADF content of oven-dry rape straw was significantly lower than the sun-drying rape straw(P<0.01); there is no obvious differences between the EE and NDF content in rape straw with the two drying methods(P<0.05); glucosinolate content of the oven-dry rape straw was 92.10% of which is in the sun-dry; the RFV of the oven-dry rape straw was significantly higher than the sun-dry rape straw(P<0.01). In general, rape straw with oven-drying methods is better than it with sun-drying methods.Experiment 5: This experiment was conducted to study the interactions between physical and chemical properties of rape straws. The results showed as follows: The number of vascular bundles had significant positive correlation with Ash content(r=0.501,P<0.05), while pith tissue area/stem crosscutting area had significant negative correlation with Ash content(r=-0.519,P<0.05);shearing force was higher relating to nutritive value of rape straw, which had significant negative correlation with CP content(r=-0.648,P<0.01), while shearing force had significant positive correlation with NDF content(r=0.591,P<0.05);the NDF content had significant negative correlation with CP content(r=-0.539,P<0.05). |
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