青割玉米非結構性碳水化合物含量變化之研究

本計畫的主要目的在探討青割玉米非結構性碳水化合物（non-structural carbohydrates, NSC）含量之變動，供反芻動物飼糧調配之參考。試驗採用國內主要青割玉米品種台農3號、台南19號及台南21號為材料，分別測定在不同期作與不同成熟度下的水溶性碳水化合物（Water soluble carbohydrates, WSC）與澱粉含量變化。春作之結果顯示，青割玉米果穗充實期間NSC含量依品種、種植環境及成熟度而異，平均占全株之15.8%-33.6%。果穗充實前期全株之NSC含量以WSC占多數，但充實後期則以澱粉為主，種植月份間雖有差異，但規律不明顯。莖葉之WSC含量維持於較穩定的狀態，苞穗之WSC含量則明顯隨成熟度大幅下降。莖葉之澱粉含量較低，苞穗之澱粉含量於吐絲後7天至14天間大幅提高，21天以後提高之幅度縮小。秋作之WSC與澱粉變化狀況與春作相似。充實後期，10月份種植者WSC含量高於8月，而澱粉及NSC含量二者相近。品種間以台南21號之WSC低於其他二品種，澱粉及NSC均以台農3號高於台南19號高於台南21號。然不論品種與環境的差異，試驗結果均顯示青割玉米在乳熟後期的NSC含量即達乾重20%以上，之後NSC繼續隨成熟度遞增，可能高至30%以上，因此餵飼利用時應注意與結構性碳水化合物間的平衡問題，以降低反芻動物發生瘤胃過酸症的潛在危險。

關鍵字

非結構性碳水化合物；水溶性碳水化合物；澱粉；青割玉米

並列摘要

The objectives of this study were to investigate the variation of non-structural carbohydrates (NSC) in forage corn. Three major varieties, Tainung No.3, Tainan No.19 and Tainan No.21 were planted in spring and autumn and the water-soluble carbohydrate (WSC) and starch contents were analyzed in different maturity. The results in spring crop showed that the NSC had a wide range of 15.8% to 33.6% of the total dry matter during the ear-filling stages according to different varieties, environments, and degrees of maturity. WSC was the major component of NSC in early ear-filling stage. WSC in stems and leaves were rather constant as compared with those in ears, which decreased significantly in late ear-filling stage. Starch contents in stem and leaves were low and quite constant, while those in ears increased dramatically during ear-filling stage. The changing patterns of NSC in fall-crop were similar to those in spring-crop. In late ear-filling stage, forage corn planted in October had higher WSC contents than those planted in August, while the contents of starch and NSC were similar. Among the three entries, Tainan No.21 had the lowest contents of WSC, starch and NSC. No matter the variation in varieties and environments, the NSC content in forage corn was above 20% in later milk stage and increased as ear became matured. Therefore, it is necessary to pay attention to the balance of structural carbohydrates and non structural carbohydrates in the diet to prevent acidosis when feeding ruminants with forage com.

並列關鍵字

Non-structural carbohydrates ； Water-soluble carbohydrates ； Starch ； Forage corn

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