Lykos T, Varga G A
Department of Dairy and Animal Science, Pennsylvania State University, University Park 16802, USA.
J Dairy Sci. 1995 Aug;78(8):1789-801. doi: 10.3168/jds.S0022-0302(95)76804-7.
Two ruminally cannulated Holstein cows in early lactation were used to determine the effects of heat treatment and particle size on fractional degradation rates and ruminal degradabilities of DM, CP and total nonstructural carbohydrate of dry shelled corn and soybeans. A randomized complete block design with cows as blocks was used. Carbohydrate sources were cracked corn, chick cracked corn, finely ground corn, and steam-flaked corn. Protein sources were soybeans that were roasted at 144 degrees C, cracked, or ground through a 4-mm screen and raw soybeans that were cracked or ground through a 4-mm screen. Reduction in particle size increased both degradability of total nonstructural carbohydrate in the rumen. Heat treatment decreased degradability of CP and increase degradability of total nonstructural carbohydrate in the rumen for both protein and carbohydrate sources. Roasting of soybeans decreased degradability of all AA except Lys. However,reduction in particle size had a stronger effect than heat treatment on ruminal degradability of CP and AA of soybeans, but had the opposite effect on total nonstructural carbohydrate degradability from corn. Methionine, Leu, and Thr had the lowest ruminal degradability across all soybean sources, and Lys and Val were the most degradable. The AA profile of the RUP fraction of soybeans differed from that of the original feed-stuff and was affected by processing method.
选用2头处于泌乳早期的装有瘤胃瘘管的荷斯坦奶牛，以测定热处理和粒度对干脱壳玉米和大豆的干物质（DM）、粗蛋白（CP）以及总非结构性碳水化合物（TSC）的降解率和瘤胃降解性的影响。试验采用以奶牛为区组的随机完全区组设计。碳水化合物来源包括碎玉米、鸡碎玉米、细磨玉米和蒸汽压片玉米。蛋白质来源包括在144℃下烘烤、破碎或通过4毫米筛网研磨的大豆，以及破碎或通过4毫米筛网研磨的生大豆。粒度减小提高了瘤胃中总非结构性碳水化合物的降解性。热处理降低了蛋白质和碳水化合物来源的CP降解性，并提高了瘤胃中总非结构性碳水化合物的降解性。大豆烘烤降低了除赖氨酸外所有氨基酸的降解性。然而，粒度减小对大豆CP和氨基酸瘤胃降解性的影响比热处理更强，但对玉米总非结构性碳水化合物降解性的影响则相反。在所有大豆来源中，蛋氨酸、亮氨酸和苏氨酸的瘤胃降解性最低，赖氨酸和缬氨酸的降解性最高。大豆RUP部分的氨基酸组成与原始饲料不同，并受加工方法影响。
