Study On The Nutritional Value Of Grass And Shrub Forage Correlated To The Forage Selectivity By Hainan Eld's Deer

Hainan eld's deer (Cervus eldi hainanus) (written "the eld's deer" in this paper) is one of the four tropic rare deer species, it is regarded as the first-class animal under protection in China and as one of the severe endangered species by the International Union for Conservation of Nature and Natural Resources (IUCNI) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Presently, the natural population number of the eld's deer is about 1200, which was developed based on the number of 26 in 1976, in the enclosure of Hainan Datian National Nature Reserve, and the population density in the enclosure has exceeded 0.9 头/ hm2. Because of the dry season of about 8 months per year in Datian region, the eld's deer could not graze enough in the enclosure, they has been in the face of serious nutrition pressure. The 《Programming of Hainan Eld's Deer Salvation》 , studied out by the National Forestry Office, suggested that the "feeding management of semi-captive" should be the basic feeding mode for the eld's deer salvation and development in the the enclosure of Datian Nature Reserve, however, it could not give any useful nutritional parameters or feeding technology related.In the enclosure, the eld's deer grazed the forage of grass and shrub species mainly. As the eld's deer grazed the forage in selectivity, the "forage nutritional value", "forage available biomass", "feeding frequency" and "forage preference" by the eld's deer would be different from the past. What relationship existed between the forage selectivity by the eld's deer and the nutritional value of the forage? Which nutrients the forage in the enclosure could not supply the eld's deer sufficiently, especially in dry season? In any case, in order to practise the "feeding and management of semi-captive"efficiently, it is very useful to answer the questions, which are related to the Eco-nutrition of the eld's deer.Of the study, the observation on the eld's deer grazing and the collection of the forage and faecal examples were processed on the basis that the eld's deer graze the forage at freedom in the enclosure. The following methods, "direrct observation of feeding", "evidence of feeding on forage", "feeding trial of simulating the forage species grazed by the eld's deer", "acid insoluble ash", "crude nutrient ananysis" and "Van Soest fibredilution" were used. Of the forage of 18 grass and 18 shrub species, the following indexes, "feeding frequency", "forage comparatively grazed biomass", "forage preference", "forage intake and cookbook" and "apparent digestibility of crude nutrients " by the eled's deer were observed. Meantime, the related forage samples were collected from the enclosure, the content of water, aether extract (EE), crude ash (CA), nitrogen-free extract (NFE), crude protein (CP), limiting amino acids (LAAs), sulphur-amino acids (M+C), crude fibre (CF), acid dilute fibre (ADF), lignin, calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn) and copper (Cu) of each forage sample was determined.The study showed that, counting on the average of dry season and wet season, ofshrub forage, the CP, LAAs, (M+C), EE, Ca, Fe, Mn, Zn and Cu content, 13.60%, 6.46%,3.75%, 0.29%, 0.72%, 206.88mg/Kg, 53.36mg/Kg, 22.52mg/Kg and 13.00mg/Kg, wassignificantly higher than that of grass forage, 9.75%, 3.9%, 3.17%, 0.84%, 0.45%,110.70mg/Kg, 29.66mg/Kg, 11.03mg/Kg and 6.75mg/Kg, respectively (P<0.05); NFEcontent, 45.25%, was lower to that of grass forage, 46.64%, but the difference was notsignificant (p>0.05); Water and CF content, 65.83% and 21.70%, was significantly lowerthan that of grass forage, 70.16% and 24.71%, respectively (P<0.05). In the enclosure,grass forage, containing abundance of organic nutrient, was the main energy supply for theeld's deer, however, shrub forage, containing higher content of protein and microelements,was the important nutritional resource for the eld's deer tc get a balanced eco-nutritionalrequirement based on such an unsuited habitat that the dry season in Datian region is solong that grass forage faded for a very long time. In dry season, the digestibility of NFEand CF, 50.42% and 35.33%, was significantly lower than that in wet season, 55.60% and40.18%, respectively (P<0.05), and this difference was due to that the forage fibrousmateriels content in dry season was higher than that in wet season. The foragecomparatively grazed biomasses were greatly different, from 1.61% to 16.56% in grassspecies and from 0.58% to 11.82% in shrub species, and the so great difference was due tothat the eld's deer graze different forage species in selectivity in the enclosure. In fact that,the forage preference of 18 grass and 18 shrub species were greatly different, from 0.16 to3.15. Also, the eld's deer grazed differen forage parts in selectivity, they prefer to graze theupside of a whole plant, for examples, only the upper 1/2 portion of a whole grass or onlythe green leaves of upper 1/2 portion of a whole shrub bough. As the eld's deer grazed theforage in selectivity, the available biomass of some shrub forage, those were muchprefered by the eld's deer in the enclosure, decreased gradually in the past 10 years, so that the shrub forage preference sequence present is different from that of 10 years before.In order to know if the nutritional value and available biomass of the forage in the enclosure accord with the eld's deer nutrition requirement, the corelations between the forage species selectivity by the eld's deer and the forage nutrients content, and between the selectivity to the grazing part of the forage by the eld's deer and the forage fibrous materiels content, wsre analyzed. The study revealed that, wether grass or shrub species, as the CP, EE, LAAs, (M+C), Ca, Fe, Mn, Zn and Cu content increased, the forage preference degree (greatly) increased in correspondence, so it was considered that these nutrients were the ones which could not reach the satisfaction of the eld's deer nutritional requirement, and they should be taken in attention when supplying forage to the eld's deer in dry season. However, as the ADF and Lignin content increased, the ratio of grazed portion/a whole forage by the eld's deer was greatly decreased, so it was considered that the fibrous materiel were the limiting ones for the eld's deer to extend the grazing portion of the forage to get much nutrient intake in the enclosure.In this study, nutritional value of the forage mainly grazed by the eld's deer in the enclosure of Hainan Datian Nature Reserve was analyzed, correlation among the forage nutritional value, forage available biomass and forage selectivity by the eld's deer was revealed, some nutrients or factors, which could not reach the satisfaction of the eld's deer nutritional requirement or limit the eld's deer to extend the grazing portion of the forage were found out, the nutritional mechanism and measures about the eld's deer "feeding and management of semi-captive" were proposed and some nutrients requirement of the eld's deer were suggested.