Study On Grazing And Utilization Of Goats On A Shrubland In The Three Gorges Region Of Yangtz River

A study was conducted on a naturely shrubland of Hejiaping on the county of Changyang inHubei Province from May to September in 1999 and from June to September in 2000.The studywith 9 local wethers was designed as three treatments including the control, the light- and heavy-grazing. The changes of community structure, yield, nutrition of shrubland and acceptability indexof shrubland plant under the different grazing intensities were systematically studied.The results were showed as follows: (1) The extremely significant (p<0.01)positivecorrelation between the fresh weight (Y) of new branches and leaves and up-ground and crownwidth (D) could be expressed by a function as Y=a D in the study. (2) The content of crudeprotein of Dacbergia hupeana Hance. was the highest, those of Jndigofrra ic/zangensis Craib andLespedezaformosaLes were in the second places, and their contents of crude protein in the drymatter were 17%, 16% and 15.7% respectively. The content of crude protein of Miscanthussinensis was the lowest (4.6%). (3) The dietary composition of shrub was higher under the light-grazing treatment than under the heavy-grazing treatment (1999 and 2000). The dietarycomposition of shrub (1999) under the light- and heavy-grazing treatments were 62% and 55%respectively in July, and were 78% and 51% respectively in September. The dietary compositionof shrub (2000) under the light- and heavy-grazing treatments were 6 1.2% and 44.4% respectivelyin June, and were 36.2% and 23.2% respectively in August. The acceptability index of shrubbyplants in 1999 was 33% and extremely significant (pO.O5) in the acceptability index of shrubs, grasses and forb in 2000 (21.3%, 13% and 11.6%respectively). (4) The yield composition and seasonal change on shrubland in the Three GorgesRegion of Yangtz river mainly depended on the seasonal growth and decline of grasses, and thechanging trends of production of grasses and total yield of shrubland were consistent. The yieldsof the control, the light- and heavy-grazing treatments in September were the highest and were3042.8, 2518.4 and 1180.3DM kg/ha respectively. A lot of rainfall could play a role in a certaindegree in the compensatory growth of plants that were consumed by animals. The net primarygrowth of plant on shrubland was lower under the light- and heavy-grazing treatment than underthe control treatment in August because of the severe lack of rainfall. The net growth of plant wasover-compensatory under the light-grazing treatment and low-compensatory under the heavy-grazing treatment. The average utilization efficiencies of grasses, forb and shrubs were 53.4%,40.4% and 9.1% respectively in June and were 47.4%, 73% and 39% respectively in August. (5)The species diversity and even index of shrubby community almost kept constant under thecontrol treatment and their average values were 2.0876 and 0.8715 respectively. The speciesdiversity and even index of shrubby community declined under the light-grazing treatment andincreased under the heavy-grazing treatment. The species diversity and even index of herbagecommunity declined under the light- and heavy-grazing treatments.The superiority of Lespedezaformosa/es in shrubby community declined under the grazing treatment especially the heavy-grazing treatment because of its relatively high content of crude protein and good preference, andsequential regrowth would improve its superiority in shrubby community. The regrowth ofIndigofera ic/langensis Craib was stimulated under the light-grazing treatment and was affectedunder the heavy-grazing treatment, so the stocking rate should be control lest Indigoferaichangensis Craib decline. (6) The daily gains of grazi...