| Summary: | 碩士 === 國立嘉義大學 === 動物科學系研究所 === 106 === Fresh corn is a popular forage source for cows due to its high yielding properties, energy content, relatively high palatability, and incorporating easily into TMR. However, the quality of fresh corn in Taiwan are variable due to various planting seanson and harvesting time. Therefore, how to establish a simple method to determine the quality of fresh corn is quietly important. The aim of the study was to investigate the feasibility of determining the quality of fresh corn by extruding strength. Treatment that collected fresh corn (n=48) harvested from February to May conducted chemical analysis and extruding strength test. The results showed that DM, CP, NDF, ADF and starch content were between 19.1 to 34.2%, 7.0 to 9.9%, 43.8 to 62.0%, 25.0 to 34.4% and 13.5 to 34.5%, respectively. CP, NDF and ADF content decreasing with increasing DM content. Nevertheless, starch content increasing with DM content increasing. It showed that DM and starch content had more variation, but CP content had less variation. The DM content of samples mainly distributed on 22 to 32%, and there were 77% DM content of samples under 30%. The starch content of samples mainly distributed on 19 to 31%, it had the similar distribution as DM content. The NDF content of samples mainly distributed on 51 to 61%. There are 87% ADF content of samples distributed on 27 to 33%, and 54% CP content of samples distributed on 8 to 9%. Different harvesting months didn’t affect DM, NDF, ADF and starch content of fresh corn. However, the CP content of fresh corn were significantly difference between each months (P < 0.05 ), and February had higher CP content (9.29%), and March and April had lower CP content (8.54%, 8.37%). According to 6 different level of extruding strength to investigate the correlation coefficients among chemical composition of fresh corn, the reslts showed that starch positively correlated to DM, and NDF, ADF negatively correlated to DM (P < 0.05). In the association between extruding strength and chemical composition of fresh corn, extruding strength had more association with DM and starch, the coefficient of determination (R2) were 0.77 and 0.73, respectively. On the other hand, extruding strength had less association with NDF and ADF, the coefficient of determination (R2) were 0.34 and 0.33, respectively. In conclusion, using extruding strength with extruding strength table can be used to determine the quality of fresh corn when adjusting rations.
Key words: dry matter, extruding strength, fresh corn, starch
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