The Seasonal Dynamics Of Condensed Tannins Of Some Dominant Grasses And Shrubs On Alpine Meadow And Their Feeding Values

Alpine meadow is one of the most important grazing grassland in Qinghai Tibetan lateau. In present study, four trials were carried out to analyze the effects of condensed tannins on in sacco DM disappearance and in vitro gas production, and the feeding value of several dominant forages and shrubs on alpine meadow was also evaluated. Trial one: the seasonal dynamics of total extractable condensed tannins (TECT) if above forages and shrubs were determined by Acid Vanillin IIC1 Method. The results snowed that all tested shrubs and some forages contained TECT. P. viviparom bus the highest TBJT content (120. 0 g/kg DM) in July, and the average TECT content in tiVe months was 77.56 gjkg DM. Catrofusca and mix sample contained low TECT content. \o TECT was detected in other tested forage samples. The average TECT contents of 9. frutirosa, 5 alpina. C. jubata, H. tibetica and S mvstillacea in four months were 54. 30, 29. 18, 42. 15, 67. 08 and 58. 53 g, kg DM. And the TECT contents decreased it the maturi tv of shrubs .Af ter August TECT contents iii all shrubs ver?less than 6 gikg DM. It suggested that the utilization of alpine shrubs after August wouu oe safe and suitable. The utilization of P. vivipanrnj grassland would, he safe iii whole season except for high amount of P. viviparum in this grassland. Trial two: the seasonal dynamics of the concentration of crude protein(CP). wctd detergent fiber(.ADF) and crude ash were deterzined by routine methods. The average concentration of CP of Crex atrofusca. Xobresia eapillifo]iu, Titigone]i; mthenica. Po]vgonu~ vivipaim Elvmus nu vans and mix sample of Poligonum VI viparum grassland, in four months, were 9.87. 12,84, 18. 62, 14. 25, Ii. ?~aici 12. 32%, respectively; the average concentration of ADF was 27. 94, 29. 03, 20. 91, 24. 80. 30. 36 and 28. 69%, respectively. The .ADF content of these forages iiinr~ased at the degree of maturity, while the C? content decreased. The C? contents of Dasiphora fruticosa. Spiraea alp lila, 6arugana juba vu. Hippophae tihevica and SuIix ,vvstillacea in four months were 10. 40, 15.38, 17. 31, 21.27 and 15. 27%. respectively: the ADF contents were 26. 24, 25. 68, 28. 27, 20. 07 and 26. 78%, respect ivelv. The C? content also decreased with the increase of maturity of shrubs. The æ…³verage C? content of shrubs (16%) is higher than that of forages (14%,. p>0. 05), the ADF content is no more than 30%, and has no regular change. Trial three: the potential dry matter degradabilitv (DMD) of some forages and -46 shrubs and the relationship between TECT and 48h DMD were determined by in sacco nylon bag method in fistula yaks. The results showed that all forages had the highest DMD in June, and the 48h DMD in June of K capi]]ifolia, 1. ruthenica, P. viviparuu~? E. nutans and the mix sample of P. - viviparuln grassland were 83. 18, 84. 37, 81. 05, 69.68, 84.27 g/kg DM. From June to September they decreased by 25, 21, 9, 25 and 40%, respectively. The 48h DMD of shrubs was lower than that of forages (p<0. 01). The average 48h DMD in four months of D. fruticosa, S. alpina, C. jubata, II. tibetica and S. nvsti1lacea was 55. 1, 62.0, 55.2, 45. 5 and 67. 4%, respect ivelv. No significant relationship was found between TECT and 48h DMD in all forages and shrubs. Trial four: the gas pro~duction of those forages and shrubs and the effect of TECT on rumen degradability were determined with or without PEG by Gas Production...