| Blue sheep(Pseudois nayaur)was listed in the ? grade nationally protected animals of China.Helan Mountains is the eastern edge of their distributions.Our research mainly targeted on blue sheep,red deer(Cervus elaphus),sheep(Ovis aries)and goat(Capra aegagrus hircus)in this area,and combined anatomical morphology with nutritional ecology of blue sheep,through dissecting and measuring different digestive organs of blue sheep,explored digestive characteristics and the nutritional adaptation strategies changing with seasons of blue sheep.The main results are as follows:(1)The morphological and structural characteristics of the alimentary tract of the blue sheep showed that the tissue weight of whole stomach of blue sheep was 0.78±0.03 kg,accounting for 2.44±0.14%of the body weight.The weight of rumen and reticulum were the largest,accounting for 80.88±0.45%of the whole weight of gastric tissue.Followed by omasum,the proportion was 9.77±0.34%,and the abomasum was the smallest,the proportion was 9.35±0.42%.There was a significant positive correlation between the weight of compound stomach tissue and weight(r=0.544,F1,23=9.678,P=0.005).There was also a significant positive correlation with age(r=0.709,F1,31=31.385,P<0.001).The weight of gastric contents of stomach increased significantly with age.However,the ratio of weight of gastric tissue to body weight decreased significantly with age(r=-0.580,F1,22=11.179,P=0.003).Only body weight had a significant effect on the gastric weight of rumen and reticulum(r=0.556,F1,23=10.307,P=0.004),demonstrated that it increasedlinearly with the body weight increased.The weight of contents and tissue weight of tumor network stomach and valvular stomach were not significantly different between seasons.The pore size of passage between different stomachs chambers order by follow:omasum-abomasum passage>reticulum-omasum passage>cardiac>orifice ileo-cecal>pylorus.Only body weight had a significant effect on omasum-abomasum passage and orifice ileo-cecal,and there was no significant seasonal difference in the size of the food passage in each stomach chamber.There were significant differences in mastoid density,length and width in different regions of the rumen(P<0.001).In additional,the overall surface expansion coefficient of the rumen mucosa was 2.85±1.37.The total length of the intestinal tract of blue sheep was 26.1±0.5 times against the body length,and the small intestine accounts for about 73.06±0.29%of the total length of the intestine.There was no significant difference between the total length of intestinal tract and the length of each part between individuals,genders and seasons.Therefore,according to the morphological structure and characteristics of the digestive tract,nutritional strategy of blue sheep is the roughage feeder.(2)To compare the digestive tract structure characteristics of sheep and other species in the same region,the results implied that net weight of whole stomach of blue sheep was smaller than other sympatric species such as red deer,sheep and goat.Besides,net weight of each stomach part was also significantly lower than the same part for the above three animals.There was no significant difference between blue sheep and red deer in cardia(Z=-0.934,P=0.376).Compared with goats,there was no significant difference between the weight of gastric tissue and the weight of tissues in different parts.In comparison with sheep,except for the rumpled stomach,the weight ratios of the compound stomach and the tissues of all parts of the blue sheep were significantly lower than that of sheep.However,all the other features were significantly smaller than red deer's(reticulum-omasum passage,Z=-2.908,P<0.001;omasum-abomasum passage,Z=-2.601,P=0.003;orifice ileo-cecal,Z=-2.447,P=0.008;pylorus,Z=-2.752,P=0.001).There was no significant differences between blue sheep and goat for each passage in the digestive tract.Blue sheep had larger reticulum-omasum passage(Z=-2.277,P=0.006)and orifice ile-cecal(Z=-2.279,P=0.006).There was significant differences between blue sheep and red deer for overall surface expansion coefficient of the rumen(Z=-2.337,P=0.014).In terms of the intestinal tract,compared with the red deer,the length of the intestinal tract of the sheep was larger(Z=-2.793,P=0.001),and the small intestine and cecum of the sheep were significantly larger than that of red deer,while the small colon was significantly smaller than that of red deer.There was no significant difference between the total weight of the intestines of sheep and that of red deer.(3)The size and distribution of food particles in different parts of alimentary canal was measured,compared the differences among different individuals,genders and seasons.The results indicated rumen and reticulum had most great food particles(x>2 mm),this content can reach 27.7±3.03%.The large food particles content was gradually decreasing from omasum.The content of large-medium food particles(2.0 mm?x>1.0 mm)was also highest in the omasum,reached 6.17±1.79%.However,the content of medium food particles is lowest in the omasum(2.89±0.77%),and significantly lower than other digestive organs.The content was gradually increasing from rumen and reticulum.The rumen and reticulum(0.425 mm?x>0.25 mm)had lowest content of small food particles than other digestive organs.In addition,tiny food particles(0.25 mm?x>0.125 mm)didn't have significant differences in each digestive organs.Food particles of different sizes changed with the seasons.The large food particles content had remarkable different among rumen-reticulum,small intestine and the cecum in different seasons(F=4.44,P=0.04;F=3.95,P=0.04;F=4.47,P=0.03).For large-medium food particles,they only had significant differences in the rumen and omasum(F=6.69,P=0.02;F=7.02,P=0.01).For medium food particles,they also had significant differences among rumen-reticulum,small intestine and the cecum in different seasons(F=7.51,P=0.02;F=4.80,P=0.04;F=9.05,P=0.01).For small food particles,rumen-reticulum had lower content than other digestive organs,but difference didn't reach significance level.For tiny food particles,there was only prominent difference in the omasum,summer content(16.05±2.52%)was significantly higher than winter content(6.44 ±1.45%).(4)Nutritional components of 22 staple food and content food within rumen and reticulum from 11 blue sheep were measured.The results demonstrated that for 22 staple food foraged by blue sheep,the crude protein content was the highest in Potentilla fruticosa L(22.91%).Summer content was significantly different with winter content.The crude fat content was highest in winter Juniperus rigida S.et Z.(53.9%),all foods crude fat content changed with seasons remarkably.The content of nitrogen free extract was about 32.99%-64.03%,the highest is Amygdalus mongolica(64.03%).Most of plants didn't have significant seasons difference for free nitrogen free extract.The content of neutral washing fiber was the highest in summer bryophyte(78.64%),summer content of neutral washing fibers was significantly higher than winter content for all plants.For the nutrient content of rumen digested food of blue sheep,mean crude protein content of digested food in summer was 14.08±0.03%,and prominent higher than winter content(12.04±0.89%).Summer crude fat content was also slightly higher(35.60±0.20%)than winter content(28.80±3.28%).Summer content of neutral washing fiber(59.45±0.13%)was slightly lower than that winter too(63.59±1.99%).Summer content of acid washing fiber(52.63±0.38%)was slightly higher than those in winter(48.90±1.78%),Summer content of lignin within rumen food was significantly higher than winter's(29.95±0.97%).There was significant difference between summer and winter for NDF(3.51±0.04%vs.1.81±0.29%,P=0.02).Winter content of ADF(3.44±0.44%)was significantly higher than that within summer(1.19±0.01%)(P=0.03). |
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