摘要
Exogenous enzymes are added to diets to improve nutrient utilization and feed efficiency. A study was conducted to evaluate the effects of dietary exogenous enzyme products with amylolytic (Amaize, Alltech) and proteolytic (Vegpro, Alltech) activity on performance, excretion of purine derivatives, and ruminal fermentation of dairy cows. A total of 24 Holstein cows, 4 of which were ruminally cannulated (161 ± 88 d in milk, 681 ± 96 body weight, and 35.2 ± 5.2 kg/d of milk yield), were blocked by milk yield, days in milk, and body weight, and then distributed in a replicated 4 × 4 Latin square design. Experimental periods lasted 21 d, of which the first 14 d were allowed for treatment adaptation and the last 7 d were used for data collection. Treatments were as follows: (1) control (CON) with no feed additives, (2) amylolytic enzyme product added at 0.5 g/kg diet dry matter (DM; AML), (3) amylolytic enzyme product at 0.5 g/kg of diet DM and proteolytic enzyme product at 0.2 g/kg of diet DM (low level; APL), and (4) amylolytic enzyme products added at 0.5 g/kg diet DM and proteolytic enzyme product at 0.4 g/kg of diet DM (high level; APH). Data were analyzed using the mixed procedure of SAS (version 9.4; SAS Institute Inc.). Differences between treatments were analyzed by orthogonal contrasts: CON versus all enzyme groups (ENZ); AML versus APL+APH; and APL versus APH. Dry matter intake was not affected by treatments. Sorting index for feed particles with size <4 mm was lower for ENZ group than for CON. Total-tract apparent digestibility of DM and nutrients (organic matter, starch, neutral detergent fiber, crude protein, and ether extract) were similar between CON and ENZ. Starch digestibility was greater in cows fed APL and APH treatments (86.3%) compared with those in the AML group (83.6%). Neutral detergent fiber digestibility was greater in APH cows compared with those in the APL group (58.1 and 55.2%, respectively). Ruminal pH and NH3-N concentration were not affected by treatments. Molar percentage of propionate tended to be greater in cows fed ENZ treatments than in those fed CON. Molar percentage of propionate was greater in cows fed AML than those fed the blends of amylase and protease (19.2 and 18.5%, respectively). Purine derivative excretions in urine and milk were similar in cows fed ENZ and CON. Uric acid excretion tended to be greater in cows consuming APL and APH than in those in the AML group. Serum urea N concentration tended to be greater in cows fed ENZ than in those fed CON. Milk yield was greater in cows fed ENZ treatments compared with CON (32.0, 33.1, 33.1, and 33.3 kg/d for CON, AML, APL, and APH, respectively). Fat-corrected milk and lactose yields were higher when feeding ENZ. Feed efficiency tended to be greater in cows fed ENZ than in those fed CON. Feeding ENZ benefited cows' performance, whereas the effects on nutrient digestibility were more pronounced when the combination of amylase and protease was fed at the highest dose.
摘要译文
将外源性酶添加到饮食中，以提高营养利用率和饲料效率。进行了一项研究，以评估具有链淀粉（Amaize，AllTech）和蛋白水解（VEGPRO，ALLTECH）活性对性能，嘌呤衍生物排泄以及奶牛发酵奶牛的饮食外源性酶产物的影响。总共24头荷斯坦母牛，其中4头吐出了荷斯坦奶牛（牛奶中的161±88 d，681±96人体重，牛奶产量为35.2±5.2 kg/d），被牛奶产量阻塞，牛奶的天数，和体重，然后以重复的4×4拉丁正方形设计分布。实验期持续了21 d，其中前14天被允许进行治疗适应，最后7 d用于数据收集。处理如下：（1）没有饲料添加剂的对照（con），（2）以0.5 g/kg饮食干物质（DM; AML）添加的链液溶液酶产物，（3）链淀粉酶以0.5 g/kg的产物为饮食DM和蛋白水解酶的产物以0.2 g/kg的饮食DM（低水平； APL）和（4）以0.5 g/kg的饮食DM和蛋白水解酶产生为0.4 g/kg（高饮食DM）（高饮食DM）（高饮食DM）（高高（高）级别; aph）。使用SAS的混合程序（版本9.4； SAS Institute Inc.）分析数据。通过正交对比分析了处理之间的差异：CON与所有酶基（ENZ）；AML与APL+APH；和APL与APH。干物质摄入不受治疗的影响。对于ENZ组，尺寸<4 mm的进料颗粒的分选指数低于CON。DM和养分（有机物，淀粉，中性洗涤剂纤维，粗蛋白和醚提取物）的总消化率相似。与AML组中的牛（83.6％）相比，喂养APL和APH治疗的母牛的淀粉消化率更大（86.3％）。与APL组相比，APH奶牛的中性洗涤剂纤维的消化率更高（分别为58.1和55.2％）。瘤胃pH和NH 3 -N浓度不受治疗的影响。在饲喂enz治疗的母牛中，丙酸的摩尔百分比往往比在那些饲料中更大。在喂养AML的奶牛中，丙酸的摩尔百分比要比饲喂淀粉酶和蛋白酶的混合物的丙酸较高（分别为19.2和18.5％）。在饲喂enz和con的奶牛中，尿液和牛奶中的嘌呤衍生物排泄相似。在食用APL和APH的母牛中，尿酸排泄趋于比AML组中的尿酸排泄量更大。在饲喂enz的母牛中，血清尿素N浓度往往比在饲料中更大。与CON（分别为CON，AML，APL和APH）相比，喂养ENZ处理的母牛的牛奶产量更高。喂食ENZ时，经脂肪校正的牛奶和乳糖产量更高。在饲喂恩兹的奶牛中，饲料效率往往比那些饲养的饲料更大。喂养ENZ受益于母牛的表现，而当淀粉酶和蛋白酶的组合以最高剂量喂养时，对营养消化率的影响更为明显。
Milena Bugoni; Caio S. Takiya; Nathalia T.S. Grigoletto; Paulo Cesar Vittorazzi Júnior; ... Francisco P. Rennó. Feeding amylolytic and proteolytic exogenous enzymes: Effects on nutrient digestibility, ruminal fermentation, and performance in dairy cows[J]. Journal of Dairy Science, 2023,106(5): 3192-3202