Study On The Limiting Nutrional Factors Of Cashmere Goats Grazing On Leymus Chinensis Pasture Of Songnen Plain

Based on the observation of grazing behaviour, the nutritional status of Inner Mongolian Cashmere goat (2.5 years old, wether and does) grazing on the native and introduced Leymus Chinensis Pasture were evaluated using the n-alkane as the marks. Then combined with the results of cashmere growth performance and the activity of the secondary hair follicles of goats, the limiting nutritional factors of grazing cashmere goat were analyzed systematically.The results of observation on grazing behaviour showed, there were no sex difference on the rhythm of foraging behavior and rate of ingestion. The rhythm of foraging behaviour was similar between native and introduced Leymus Chinensis Pasture, the percentage of ingestive time in total grazing time is highest, and the following is the time of rest and rumination under lying, standing and wandering time and the drinking time. In native Leymus Chinensis Pasture, the ingestive time of spring was higher than the time in summer(P<0.05), however, the time of rest and rumination under lying, standing and wandering time, drinking time were lower than them in summer(P<0.05). In introduced Leymus Chinensis Pasture, the ingestive time showed: summer, autumn>winter>spring (P<0.05), the time of rest and rumination under lying showed: summer, winter>autumn>spring (P<0.05), standing and wandering time showed: spring, summer, winter > autumn (P<0.05).no seasonal difference was founded in the drinking time percentage in the total grazing time.The rate of ingest, ingestive time of cashmere goat grazing on native Leymus Chinensis Pasture decreased, but the bite size and the daily intake increased in summer(P<0.05);the rate of ingest in introduced Leymus Chinensis Pasture showed: spring, winterautumn,winter>spring, summer> autumn(P<0.05). There three peak time of ingest in spring, summer of native Leymus Chinensis Pasture, and in spring, summer and autumn of introduced Leymus Chinensis Pasture. The time happened in 0.5h after morning grazing began, 0.5h after afternoon grazing began, and the 2h before end grazing, respectively. But in winter, there were only two peak time of ingest of cashmere goat grazing on introduced Leymus Chinensis Pasture, that happened in morning and afternoon, respectively. In this study, the phenomenon of biting roots of herbage was not found, however, the goat had the habits to dig the pasture with the forelimb before lying down to rest or ruminant. The habit had destructed the herbage of pasture in a certain extent. The results of diet composition showed, Sonchus brachyotus, Artemisia frigida, Phragmites communis and Iris lacteal were the diet componets of Cashmere goat grazing on native Leymus Chinensis Pasture in spring. The percentage of these herbages were wether: 18.8%,60.7%,17.8% and 2.7%,respectively, does:34.3%,36.6%,26.2% and 2.9%, respectively。In summer, the herbages consumed by wether and does were Sonchus brachyotus, Artemisia scoparia, Echinochloa crusgalli, Suaeda corniculata, Xanthium sibiricum and Chloris virgata. The percentage of each diet component was wether: 9.3%, 2.3%,11.2%, 42.3%,16.3% and 18.6%, does: 24.6%, 5.4%, 3.8%, 25.2%, 8.6% and 32.4%。The spike of Leymus Chinensis was selected as the main diet component by goat grazing on introduced Leymus Chinensis. The Leymus Chinensis part bitted by goat had more crude protein and less fibre than them in the whole plant.The results of the study on nutritional status of Cashmere goat grazing on native Leymus Chinensis pasture showed Cashmere goat could intake more nutrients and obtained moderate weight gain. Except for the ME intake in August was lower than that in June, other nutrients intake were all increased. The dietary CP and ME content were similar between the June and August, but the fibre content of the diet consumed by does was lower than that consumed wether. No significantly changes were founded in the digestibility of DM, ADF and NDF, but the CP digestibility increased and E digestibility decreased in August.The evaluation of nutritional status of goats grazing on introduced Leymus Chinensis pasture showed, compared with the NRC nutrients requirements, ME and CP intake of grazing cashmere goats were 1.6~1.7 maintain requirement, and the ratio of energy and nitrogen was more balance. But, after August, the nutrients intake of goat decreased, CP and ME intake/㎏ metabolic weight decreased to 1.61~3.63g and 0.5~0.63MJ/㎏, respectively. ME intake in August closed to maintain requirement, then decreased to 0.78 maintain requirement in April. CP intakes in autumn and winter were 0.56 and 0.28 maintain requirement, and the balance between energy and nitrogen was breaked too.The results of research on Cashmere production showed, the cashmere began to growth in July, and the vigorous period was from August to January, the growth rate could reach to 2.8cm/month, the peak time of cashmere growth was in November. The cashmere yield of wehter and does were 467.41±20.2g and 356.87±17.4g,respectively, and the net cashmere rate of wether was higher than does. The secondary hair follicles entered Anagen during the August to November, the activity of secondary hair follicles began decreased gradually after the December, and most secondary hair follicles enter catagen, and then reached telogen in January. With the old cashmere sheded, the activity of secondary follicles began to increase again in April, the secondary follicles entered pre-anagen. There were no significantly differences were founded on the cashmere growth, cashmere diameter, follicles density, the activity of secondary follicles and the S/P between wether and does, and the seasonal change of these parameters were also similar.In general, from the herbages began to wilt in August to the end of ecologically fragile period in next year, the quality of dry herbage decreased, low energy and crude protein intake were the main limiting nutrional factors, and the CP is the minimum limiting factor.