豆粕热加工及酶处理提高蛋白的体外消化以及断奶仔猪蛋白、氨基酸的消化率
发布单位:凯发网站查看次数:8142
时间:2020-09-05
豆粕中含有抗营养因子,限制了猪对蛋白质的消化过程以及整体消化率。本试验评估了热加工和酶处理对蛋白质体外消化率以及断奶仔猪蛋白、氨基酸消化率的影响。
每批豆粕(48%蛋白)分为两部分:对照组(无深加工)和试验组(热加工并酶处理的豆粕)。在体外消化试验中,选择3批豆粕,每批豆粕3个重复,经过胃蛋白酶在pH 3.5下处理1.5小时(胃消化阶段),然后在胰蛋白酶和胆汁提取物在pH 6.8下处理0、0.5、1、2、4、6小时(小肠消化阶段)。根据豆粕在0.5、0.5-4、4小时至最后消化的部分,表示为快速消化蛋白、中速消化蛋白、慢速消化蛋白,以及未消化蛋白。试验选用8头断奶去势公猪(大白×杜洛克,9.43±0.40kg),经手术安置T型回肠瘘管。试验为尤登方设计,猪只随机分至3种日粮(无氮日粮、豆粕日粮、深加工豆粕日粮,日粮中以豆粕或深加工豆粕添加40%作为氨基酸唯一来源),日粮中添加三氧化二铬作为指示剂。总共进行4期试验,每期试验包括5天试验期,2天收粪期,2天食糜收集期。速消化蛋白25%(P=0.056),减少了慢速消化蛋白48%、未消化蛋白11%(P<0.05)。动物试验中,深加工提高了粗蛋白的2.3%表观回肠消化率、2.1%标准回肠消化率(P<0.05)。深加工显著提高了除脯氨酸、甘氨酸、半胱氨酸外其它氨基酸的表观、标准回肠消化率,提高幅度高达3.3%。深加工对活性赖氨酸、赖氨酸:粗蛋白没有显著影响,但是显著提高了赖氨酸和活性赖氨酸的标准回肠消化率3%。
总之,深加工豆粕体外消化速度和消化率显著提高,与动物实验结果相吻合,并且抗营养因子含量显著降低。因此,热加工和酶处理可以生产一种更优质的蛋白原料,消化速度更快,消化率更高,减少了后肠道蛋白发酵的程度。
Thermomechanical and enzyme-facilitated processing of soybean meal enhanced in vitro kinetics of protein digestion and protein and amino acid digestibility in weaned pigs
Soybean meal (SBM) contains anti-nutritional factors (ANF) that may limit kinetics and total extent of protein digestion in pigs. This study evaluated the effects of thermomechanical and enzyme-facilitated (TE) processing on in vitro kinetics of crude protein (CP) digestion and CP and amino acid (AA) digestibility in weaned pigs. Each batch of SBM (48% CP) was divided into two parts: non-processed SBM as control vs. thermomechanical and enzyme-facilitated processed soybean meal (TES) as the experimental group. For digestion kinetics, samples (three batches of non-processed SBM vs. TES) were incubated in triplicate sequentially with pepsin at pH 3.5 for 1.5 h (stomach phase) and subsequently with pancreatin and bile extract at pH 6.8 for 0, 0.5, 1, 2, 4, or 6 h (small intestine phase). Protein was classified into CPfast, CPslow, and CPresistant corresponding to CP digested within the first 0.5 h, from 0.5 to 4 h, and after 4 h plus undigested CP, respectively. Eight weaned barrows (Large White × Duroc, 9.43 ± 0.40 kg) were surgically fitted with a T-cannula at the terminal ileum. Pigs were randomly assigned to a Youden square with three diets over four periods. The three diets were an N-free diet and two diets using 40% SBM or TES as the sole source of AA with Cr2O3 as an indigestible marker. Each period included sequentially a 5-d adaptation, 2-d collection of feces, and 2-d collection of ileal digesta. The TE processing reduced ANF content in TES by 91% for lectin, 22% for trypsin inhibitor activity, 75% for β-conglycinin, and 62% for glycinin compared with SBM. In vitro, TE processing increased (P < 0.05) digested CP by 5.6% and enhanced the kinetics of CP digestion by tending to increase (P = 0.056) CPfast by 25% and reducing (P < 0.05) CPslow and CPresistant by 48% and 11%, respectively. In pigs, TE processing increased (P < 0.05) apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP in TES by 2.3% and 2.1%, respectively. The TE processing increased (P < 0.05) AID and SID of all AA up to 3.3%, except for AID of Pro and SID of Pro, Gly, and Cys. The TE processing did not change reactive Lys or Lys:CP but increased (P < 0.05) SID of Lys and reactive Lys by 3%. Combined, the greater in vitro digestion kinetics matched the greater in vivo AID and SID of CP in TES and lower ANF compared with SBM. Thus, TE processing created a protein source that is digested faster and to a greater extent than SBM, thereby lowering the chance of protein fermentation.
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