Huang Xuewei, Christensen Colleen, Yu Peiqiang
Department of Animal and Poultry Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8.
Department of Animal and Poultry Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK, S7N 5A8; College of Animal Science and Veterinary Medicine, Tianjin Agricultural University, Tianjin, China.
J Dairy Sci. 2015 Jul;98(7):4869-81. doi: 10.3168/jds.2014-9290. Epub 2015 May 7.
The objectives of this study were to systematically determine effects of conditioning temperature (70, 80, and 90°C), time (50 and 75 s), and interaction (temperature × time) during the pelleting process on co-products from bio-oil processing (canola meal) in terms of processing-induced changes on (1) protein molecular structure, (2) pellet durability index, (3) detailed chemical profile, (4) metabolic features and fractions of protein and carbohydrate, (5) total digestible nutrients and energy values, and (6) rumen degradable and undegradable content. Pellet durability was increased with increasing conditioning time. Chemical and carbohydrate profiles of co-products were not altered by pelleting process under different conditioning temperatures and times. With regard to protein fraction profiles, pellets conditioned for 50 s had higher soluble crude protein (SCP) and lower neutral detergent insoluble crude protein (NDICP) contents than those conditioned for 75 s (21.7 vs. 20.1% SCP, 16.0 vs. 16.5% NDICP, respectively). Total digestible nutrients and energy values were not altered by processing. Samples conditioned for 50 s had a higher content of rapidly degradable protein fraction (PA2) than those conditioned for 75 s (21.7 vs. 21.1% crude protein). In addition, the slowly degradable true protein fraction (PB2) was affected by the interaction of conditioning temperature and time. However, carbohydrate fractions did not differ with different conditioning temperatures and time. Different temperatures and time of conditioning during pelleting process greatly affect protein profiles without altering carbohydrate profiles. Molecular structure analyses also showed that pelleting altered inherent protein molecular structures of the co-products from bio-oil processing. Future study is needed to detect how molecular structure changes affect nutrient availability in dairy cattle.
本研究的目的是系统地确定制粒过程中的调质温度（70、80和90°C）、时间（50和75秒）以及相互作用（温度×时间）对生物油加工副产品（油菜籽粕）的影响，具体涉及加工过程中对以下方面的诱导变化：（1）蛋白质分子结构；（2）颗粒耐久性指数；（3）详细化学组成；（4）蛋白质和碳水化合物的代谢特征及组分；（5）总可消化养分和能量值；（6）瘤胃可降解和不可降解成分。颗粒耐久性随调质时间的增加而提高。在不同的调质温度和时间下，制粒过程并未改变副产品的化学组成和碳水化合物组成。关于蛋白质组分分布，调质50秒的颗粒比调质75秒的颗粒具有更高的可溶性粗蛋白（SCP）含量和更低的中性洗涤不溶性粗蛋白（NDICP）含量（SCP分别为21.7%和20.1%，NDICP分别为16.0%和16.5%）。加工过程未改变总可消化养分和能量值。调质50秒的样品比调质75秒的样品具有更高的快速降解蛋白组分（PA2）含量（粗蛋白分别为21.7%和21.1%）。此外，缓慢降解的真蛋白组分（PB2）受调质温度和时间相互作用的影响。然而，碳水化合物组分在不同的调质温度和时间下并无差异。制粒过程中不同的温度和调质时间对蛋白质分布有很大影响，但未改变碳水化合物分布。分子结构分析还表明，制粒改变了生物油加工副产品的固有蛋白质分子结构。未来需要开展研究，以检测分子结构变化如何影响奶牛的养分利用率。
