Nutritive Value of Pastures in Kars District II. Degradation Kinetics in the Rumen with Respect to Stages of Maturity


Abstract: This study was conducted to determine the ruminal degradation characteristics of nutrients with respect to pasture stage of maturity in Kars district. The nutritional parameters were dry matter (DM), organic matter (OM), crude protein (CP) and crude fiber (CF). Samples were collected from pastures of 9 vicinities of Kars district over a 28-day interval. Three adult Morkaraman rams were fitted with a rumen cannula and samples were incubated in the rumen for 4, 8, 16, 24 and 48 h. Parameters for degradation kinetics included readily degraded fraction, slowly degraded fraction, lag phase and fractional rate of passage. The cumulative disappearance rate of DM, OM, CP and CF was linearly and quadratically decreased with advancing maturity. For DM, OM, CP and CF, readily degradable fraction, slowly degradable fraction, sum of totally degradable fraction, rate constant of passage and effective degradability linearly decreased, whereas lag phases linearly increased with advancing maturity. In conclusion, stage of maturity had a great impact on the degradation characteristics of nutrients. The adverse effect of advancing maturity on the degradation of nutrients could be related to its direct effect on lignification. The data presented in this article provide important information on the rate of digestion by the ruminants of the pasture throughout the grazing season in Kars district.

Keywords: Pasture, ruminal degradation, vegetation, stage of maturity.

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