In Sacco法评定玉米的不同加工处理方式对泌乳奶牛瘤胃干物质和淀粉降解规律的影响

以3头安装有永久性瘤胃瘘管的泌乳前期荷斯坦奶牛为试验动物,在精粗比为55：45的日粮条件下,采用In sacco法测定了不同加工处理的玉米在奶牛瘤胃内干物质和淀粉的降解规律.试验结果表明,不同加工处理方法可以程度不同的影响干物质和淀粉在瘤胃中的降解,与未处理玉米相比,挤压膨化和制粒加工处理能明显的提高玉米中淀粉在瘤胃中的降解率（P＜0.05）,压扁处理对干物质降解率无明显影响（P＞0.05）,但使淀粉瘤胃降解率明显提高（P＜0.05）,烘烤与焙炒加工处理能明显的降低玉米中干物质和淀粉在瘤胃中的降解率（P＜0.01）.淀粉瘤胃降解率由高到低顺序依次为膨化玉米＞颗粒玉米＞压扁玉米＞未处理玉米＞焙炒玉米＞140℃/35min烘烤玉米.淀粉在瘤胃中的降解的影响因素最主要是淀粉的快速可溶部分和降解速率.     

注射氯化钙和 Vc对牛肉品质的影响

将宰后 8 h 的牛肉分别注射0、100、200 mmol/L 的氯化钙溶液和 0%、1%、2%的 Vc 溶液(注射量为肉质量的 5%),然后将肉样在 4 ℃下分别放置2、4、6 d,通过对其剪切力、pH、总色素进行测定,以研究注射氯化钙和 Vc 对牛肉嫩度、pH、总色素的影响.结果表明:氯化钙溶液处理显著影响牛肉的嫩度(P<0.05),但对pH和色泽的影响不显著(P>0.05);Vc 溶液处理显著影响牛肉的 pH(P<0.05),但对嫩度、色泽的影响不显著(P>0.05);Vc 和氯化钙对牛肉品质的影响没有互作效应.     

玉米粒度对青年奶山羊胃肠道发育的影响

试验采用单因素完全随机试验设计,研究不同玉米粒度对青年奶山羊胃肠道发育的影响.结果表明,日粮淀粉为35.53%时(玉米含量28.35%).给7～9月龄的青年奶山羊饲喂不同粒度玉米时,细粉玉米(平均粒度0.76 mm)与粗粉(平均粒度2.57 mm)及整粒玉米相比,趋于提高瘤胃腹囊的乳头高度.粗粉玉米组与整粒或细粉玉米组相比,皱胃容积、小肠黏膜重和大肠长度均有提高的趋势.玉米粒度不影响瘤胃腹囊和背囊的上皮厚度、固有层厚度和肌层厚度,皱胃黏膜层厚度和肌层厚度、小肠绒毛高度、绒毛面积、隐窝深度、绒毛高度/隐窝深度、上皮厚度和肌层厚度(P＞0.05).     

pH变换腌制对牛胃平滑肌嫩度、保水性及微观结构的影响

不同p H溶液腌制可以影响牛胃品质。本研究分别采用0.5%的苹果酸和0.5%的氢氧化钠溶液于4℃下对牛瘤胃和网胃进行腌制。经酸或碱腌制处理后瘤胃和网胃剪切力值显著降低(p0.05),其中经碱处理的嫩度更好。对于瘤胃,酸处理和碱处理后其增重率较对照组增幅150%,蒸煮损失由原来的50.08%分别下降到42.10%和40.23%;与对照组相比差异显著(p0.05)。对于网胃,经酸处理或碱处理后增重率与对照组差异显著(p0.05),是对照组的9.7倍;经酸或碱处理后蒸煮损失约为40.23%和38.74%。微观结构观察表明,酸或碱处理后瘤胃和网胃平滑肌纤维结构均发生一定弱化。综上所述,酸、碱处理均可以改善网胃和瘤胃其嫩度,在一定程度上提高其保水性。     

碱/硫脲双溶剂体系制备再生冷水可溶性淀粉

借助氢氧化钠和硫脲作用制备再生冷水可溶性淀粉(regenerated cold water soluble starch,RCSS)。当配制质量分数为10%的淀粉溶液时,加入19.2%氢氧化钠(以淀粉质量计)以及14%硫脲(以淀粉质量计),搅拌10 min,淀粉可以很好溶解于溶液中,醇直接分离制备的RCSS能达到55.6%的溶解度。通过不同分离提纯方式对RCSS溶解度的影响因素进行探究,结果表明调pH水提醇沉法制备RCSS性能最佳,可以使得RCSS的溶解度达到80.5%,灰分为0.75%。     

碱/尿素双溶剂体系促进玉米淀粉的冷水溶解研究

借助氢氧化钠和尿素作用共同破坏玉米淀粉内氢键,促进玉米淀粉在冷水中的溶解性能。利用正交实验,通过考察溶液体系透光率,获得最优溶解体系。当体系固含量为10%时,5 g玉米淀粉中加入16.8%氢氧化钠(以淀粉质量计)和12%尿素(以淀粉质量计)搅拌10 min,体系透光率可达80%左右,玉米淀粉能较好地溶解在冷水中。     

甜菜颗粒替代玉米对奶牛消化及瘤胃消化动力的影响

试验使用4头安装有瘤胃瘘管和十二指肠套管的处于泌乳后期的中国荷斯坦奶牛,研究了甜菜颗粒替代玉米对荷斯坦奶牛消化和瘤胃消化动力的影响。试验日粮中粗饲料(玉米青贮+紫花苜蓿)占40%,精饲料占60%,精饲料中的玉米分别用0%、6%、12%和24%的甜菜颗粒进行替代(干物质基础)。4个处理组日粮中的中性洗涤纤维和淀粉的质量分数分别为(24.3%,34.5%)、(26.2%,30.6%)、(28.0%,26.5%)和(31.6%,18.5%)。结果表明,随着甜菜颗粒替代玉米比例的提高,瘤胃干物质周转率下降,瘤胃中性洗涤纤维的周转率提高;潜在降解中性洗涤纤维在瘤胃中的降解率提高,而且降解的速率也提高了,最终日粮总消化道的中性洗涤纤维的消化率提高了。不可消化中性洗涤纤维的瘤胃外排速率并没有受到不同处理的影响。瘤胃淀粉的消化率随着甜菜颗粒替代玉米比例的提高而显著下降,但是,总肠道淀粉的消化率并没有受到影响。随着甜菜替代玉米比例的提高,日粮纤维的消化率显著提高,淀粉的消化率没有受到影响。因此,处于泌乳后期的奶牛在低粗饲料饲喂条件下,日粮中15%~20%的玉米可以用甜菜颗粒进行替代。     

玉米粉碎粒度对产后奶牛瘤胃发酵及生产性能的影响

旨在研究玉米粉碎粒度对泌乳早期奶牛瘤胃发酵、产奶量及乳成分的影响。试验选择4头泌乳天数为14 d,日产奶量25 kg左右,体重550 kg左右的经产(二胎)中国荷斯坦泌乳奶牛,随机分为两组,对照组奶牛日粮添加10%的破碎玉米,将对该比例破碎玉米由细粉碎玉米代替,作为试验组。试验采用2×2交叉试验设计,每期21 d。结果表明:试验组奶牛瘤胃液pH值显著低于对照组(P0.05);与对照组相比,试验组奶牛瘤胃液乙酸、丙酸与对照组相比有所增加,乙丙比例降低,丁酸具有增高的趋势,与对照组相比提高了17.77%,但差异均不显著(P0.05)。试验组奶牛瘤胃液微生物蛋白与对照组比较有增加的趋势,合成效率与对照组比较无显著性差异(P0.05);试验组奶牛瘤胃液氨态氮的含量显著低于对照组(P0.05)。试验组奶牛产奶量高于对照组,乳脂率与对照组相比有所降低,但差异均不显著(P0.05);随着玉米粉碎粒度的降低,奶牛乳中乳蛋白率有增高趋势,与对照组相比提高了7%;试验组奶牛乳中尿素氮显著低于对照组(P0.05)。说明在本试验条件下,细粉碎玉米替代日粮中部分破碎玉米,可以提高奶牛瘤胃的发酵功能,使奶牛乳中乳蛋白率有增高趋势。     

苹果酸对山羊瘤胃纤维降解率及发酵类型的影响

以4头装有永久性瘤胃瘘管的本地山羊为试验动物,采用4×4拉丁方设计,研究苹果酸(0、5、10和15 g/d)对山羊瘤胃纤维降解率及瘤胃发酵类型的影响。结果表明,日粮中添加苹果酸能够显著提高瘤胃内中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的降解率(P<0.05);瘤胃液中乙酸与丙酸比值显著降低(P<0.05),改变了瘤胃发酵类型;氨态氮浓度显著降低(P<0.05),促进了瘤胃微生物对氨、氮的利用。     

新型交联活性玉米多孔淀粉的制备及工艺优化

以玉米淀粉为原料,经过三偏磷酸钠交联及高温溶胀活化处理制备交联活性玉米,再采用酶水解法制备新型交联活性玉米多孔淀粉。通过粒径及BET分析,发现淀粉颗粒明显膨胀,比表面积增大。以吸水、吸油率的大小为指标衡量多孔淀粉的吸附性能,通过单因素及正交试验,考察了淀粉乳浓度、加酶量、酶解温度、酶解pH、酶解时间对吸附性能的影响,并对酶解工艺进行优化。结果表明,最佳的酶解工艺为淀粉乳浓度15%,加酶量2.0%,酶解温度45℃,酶解pH 4.4。此时所得交联活性多孔淀粉的吸水率为172.8%,吸油率为144.8%。     

氧化糯玉米淀粉的制备及性能研究

以糯玉米淀粉为原料,以次氯酸钠为氧化剂,氢氧化钠为催化剂,对氧化糯玉米淀粉的制备及性能进行了研究.考察了反应时间、反应温度、次氯酸钠用量、pH对氧化糯玉米淀粉羧基含量的影响,采用酸碱滴定法测定氧化糯玉米淀粉羧基含量.试验结果表明,随着次氯酸钠用量增加,氧化糯玉米淀粉的羧基含量也随之增大;在一定时间范围内,氧化糯玉米淀粉的羧基含量随反应时间的增加而增加;反应温度和pH对氧化糯玉米羧基含量的影响呈倒抛物线趋势,存在最大值.糯玉米淀粉经氧化后,其液透明度和黏度热稳定性提高,但其冻融稳定性和凝沉性下降.     

Thermo-alkaline treatment. A process that changes the thermal properties of corn starch

This research focuses on the study of the thermal properties of starch corn processed using thermo-alkaline treatment. Using Modulated Differential Scanning Calorimetry (MDSC) these investigators studied the changes during gelatinization of starch in alkaline solution water-calcium hydroxide Ca(OH)2 at concentrations from 0.1 to 0.3% (g Ca(OH)2 /g dry starch). The scanning was carried out at 80% (w/w) moisture and 5 °C/min in nitrogen environment. Similarly, thermogravimetric analysis (TGA) was used to study the thermal degradation of starch treated utilizing this method. The treated starch was subjected to heating ramps from Troom to 800 °C using different rates. The MDSC results indicate that the interaction of calcium ions and starch shifts the gelatinization peak to higher temperatures when the concentration increases. In the same manner results show changes in the enthalpy values of the transition compared to when gelatinization occurs only in the presence of water. However, the disruption power of alkali has a limit. On the other hand, TG data of the principal stage of degradation permitted to find the activation energy of raw and treated corn starch, using Friedman, Flynn-Wall-Ozawa and also Kissinger methods. TGA analysis demonstrated that thermo-alkaline treatment with Ca(OH)2, had a decelerator role in thermal degradation of corn starch. More complete knowledge of activation energy as a barrier to initiate decomposition process helped in the understanding of thermal decomposition stability of corn starch when thermo-alkaline treatment is used in food industry.     

Effect of different levels of rapidly degradable carbohydrates calculated by a simple rumen model on performance of lactating dairy cows

Aggregating rumen degradation characteristics of different carbohydrate components into the term modeled rapidly degradable carbohydrates (mRDC) can simplify diet formulation by accounting for differences in rate and extent of carbohydrate degradation within and between feedstuffs. This study sought to evaluate responses of lactating dairy cows to diets formulated with increasing levels of mRDC, keeping the supply of other nutrients as constant as possible. The mRDC content of feedstuffs was calculated based on a simple rumen model including soluble, washable, and nonwashable but potentially degradable fractions, as well as the fractional degradation and passage rates, of sugar, starch, neutral detergent fiber, and other carbohydrates. The mRDC term effectively represents the total amount of carbohydrates degraded in the rumen within 2 h after ingestion. Fifty-two lactating Holstein cows (of which 4 were rumen fistulated) were assigned to 4 treatments in a 4 × 4 Latin square design. Treatments were fed as a total mixed ration consisting of 25.4% corn silage, 23.1% grass silage, 11.6% grass hay, and 39.9% concentrate on a dry matter basis. Differences in mRDC were created by exchanging nonforage neutral detergent fiber-rich ingredients (mainly sugar beet pulp) with starch-rich ingredients (mainly wheat) and by exchanging corn (slowly degradable starch) with wheat (rapidly degradable starch) in the concentrate, resulting in 4 treatments that varied in dietary mRDC level of 167, 181, 194, or 208 g/kg of dry matter. Level of mRDC did not affect dry matter intake. Fat- and protein-corrected milk production and milk fat and lactose yield were greatest at 181 mRDC and decreased with further increases in mRDC. Milk protein yield and concentration increased with increasing mRDC level. Mean rumen pH and diurnal variation in ruminal pH did not differ between treatments. Total daily meal time and number of visits per meal were smaller at 181 and 194 mRDC. Despite milk production responses, increasing dietary mRDC levels, while maintaining net energy and intestinal digestible protein as well as other nutrients at similar levels, did not influence rumen pH parameter estimates and had minor effects on feeding behavior. These results indicate that aggregating rapidly degradable carbohydrate content into one term may be a simple way to further improve predictability of production responses in practical diet formulation for lactating dairy cows.     

硫酸钠保护法制备非晶颗粒态玉米淀粉

硫酸钠具有抑制淀粉颗粒糊化的特性,可以在碱处理制备非晶颗粒态过程中抑制淀粉颗粒的膨胀。将玉米淀粉在按不同的比例的氢氧化钠和硫酸钠混合溶液在室温下处理,用偏光显微镜观测处理后的淀粉颗粒结构变化。结果表明：当质量分数3％的氢氧化钠溶液和质量分数为15％的硫酸钠溶液等体积使用时,可以制备出较好的非晶颗粒态玉米淀粉。     

Ruminal fermentation and intestinal flow of nutrients by lactating cows consuming brown midrib corn silages.

Rumen characteristics and digestive kinetics of brown midrib corn silage were evaluated with five late-lactation (221 DIM +/- 20 d) multiparous cows fitted with ruminal and duodenal cannula. Dietary treatments were applied by using a single reversal design with two 21-d periods where either brown midrib (BM3) or isogenic (ISO) corn silage were included in a total mixed ration formulated to be 40% concentrate and 60% corn silage on a dry matter (DM) basis. Rumen and total tract digestibilities of DM, organic matter, neutral detergent fiber, acid detergent fiber, starch, and N were determined and rumen characteristics evaluated. Apparent rumen DM and organic matter digestibilities were greater for the BM3 corn silage (7.1 and 4.7 percentage units, respectively). Dietary intake and duodenal flow of starch were greater and rumen and total tract starch digestibilities were lower for BM3 corn silage diets than ISO corn silage diets. However, more starch (1.1 kg/d) was apparently digested and absorbed postruminally in cows fed the BM3 corn silage diets. Duodenal flow of neutral detergent fiber was 0.9 kg/d lower, and ruminal (15.9 percentage units) and total tract digestibilities (4.4 percentage units) were higher for BM3 treatment compared with the ISO treatment. Digestive patterns of ADF were similar for the BM3 and ISO treatments. Ruminal pH was lower in the cows fed the BM3 corn silage than those fed the ISO corn silage. As a result of a tendency for decreased N excretion in urine and slight increases in N intake due to increased DM intake, N balance tended to be greater for the BM3 treatment compared with the ISO treatment. These results may partially explain the benefits of feeding BM3 corn silage to cows during early lactation, as the observed increases in fiber component digestibility and improved N economy may combine to enhance DM intake and better support the nutritional demands of milk production for the high producing dairy cow.     

The effects of source and concentration of dietary fiber,starch, and fatty acids on the daily patterns of feed intake,rumination, and rumen pH in dairy cows

The daily patterns of feed intake and rumination influence rumen fermentation, rumen pH, and timing of absorbed nutrients in the dairy cow, but the effects of diet composition on these patterns are not well characterized. Data from 3 previously published experiments were examined to determine the influence of dietary starch, fiber, and fatty acids (FA) on daily patterns of intake, rumination, and rumen pH. Dietary neutral detergent fiber (NDF) and starch were investigated in 2 experiments, each with duplicated 4 × 4 Latin square designs with a 2 × 2 factorial arrangement of treatments in cows fed cows 1×/d at 1200 and 1400 h, respectively. To investigate fiber content and digestibility in the first experiment, brown midrib or isogenic conventional corn silage were fed in low- and high-NDF diets (29 and 38%, respectively). To investigate starch source and concentration in the second experiment, ground high-moisture corn or dry ground corn were fed in low- and high-starch diets (21 and 32%, respectively). Effect of fat concentration and saturation was investigated in the third experiment using a replicated 4 × 4 Latin square design that fed cows 1×/d at 0900 h; treatments included a control diet with no added fat and 2.5% added saturated FA, unsaturated FA, or a mixture of the saturated and unsaturated FA. In the first 2 experiments, intake followed a similar daily pattern regardless of starch and NDF concentration or digestibility. Rumination displayed a treatment by time interaction for both NDF and starch concentration, with high-fiber, low-starch diets causing greater rumination overnight but not midday. High-starch diets decreased total daily rumen pH equally across the day, but did not change the daily pattern. Type of corn silage did not affect the daily patterns of rumination or rumen pH, but pH was reduced throughout the day in brown midrib diets. In the third experiment, no interactions between fatty acid supplement and time of day were observed for intake, rumination, or rumen pH. Within all experiments, rumination fit or tended to fit a 24-h rhythm regardless of diet, with the amplitude of the rumination being reduced in low-starch diets and diets containing saturated FA or a mixture of saturated and unsaturated FA. Overall, intake, rumination, and rumen pH follow a daily pattern that was minimally modified by dietary fiber and starch type and level or fat level and fatty acid profile.     

微波辅助羧甲基玉米淀粉的制备及其上浆性能

为获得对纯棉高支纱线具有优良上浆效果的浆料,以玉米淀粉为原料,一氯乙酸为醚化剂,氢氧化钠为催化剂,微波辅助制备了一种亲水改性淀粉浆料羧甲基玉米淀粉(CMCS)。借助红外光谱仪和扫描电子显微镜对产物的分子结构和颗粒形态进行分析,并对其理化特性及对纯棉纤维的黏附性进行研究。结果表明：玉米淀粉大分子上成功引入了羧甲基取代基团, CMCS 颗粒出现不同程度破损,完整性遭到破坏;CMCS 的特性黏数和表观黏度降低,流动性增强,其溶解性、膨胀性和糊透明度提高,抗凝沉性增强,蓝值下降,直链淀粉发生降解;CMCS 的糊化温度下降,糊化性能和糊加工性能得到改善;CMCS 黏附性能相比于原淀粉最高可增加27. 9%,并且随着取代度的提高,黏附性逐渐增强。对9. 67 tex 纯棉纱上浆实验结果表明,CMCS 浆纱的力学性能显著提高,其浆纱的断裂增强率与耐磨增强率分别比原淀粉浆纱增加了118. 5%和88. 7%,伸长率降低了29. 7%。     

羟丙基糯玉米淀粉合成工艺及性能研究

本文以糯玉米淀粉为原料，以环氧丙烷为醚化剂、氢氧化钠为催化剂、硫酸钠为抑制膨胀剂，对糯玉米羟丙基淀粉合成工艺及其性能进行了研究，探讨了糯玉米淀粉乳浓度、环氧丙烷用量、反应时间、反应温度、氢氧化钠用量及硫酸钠用量对糯玉米羟丙基淀粉取代度和反应效率的影响。实验结果表明，增加环氧丙烷用量、延长反应时间，可使羟丙基淀粉取代度增加。对糯玉米羟丙基淀粉的冻融稳定性、透明度及粘度进行研究表明，随着羟丙基糯玉米淀粉取代度的增加，其冻融稳定性和透明度增加，但粘度却降低。     

Effects of diet fermentability on efficiency of microbial nitrogen production in lactating dairy cows

Effect of diet fermentability on efficiency of microbial N production was evaluated. Eight ruminally and duodenally cannulated Holstein cows (55 +/- 15.9 days in milk; mean +/- SD) were used in a duplicated 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Experimental diets contained either ground high moisture corn (HM) or dry ground corn (DG) at two dietary starch concentrations (32 vs. 21%). All diets were formulated for 18% CP, and the sources of dietary protein were alfalfa silage (50% of forage at DM basis), soybean meal, distillers grain, and blood meal. The amount of OM truly fermented in the rumen varied from 7.7 (DG at 21% dietary starch) to 11.3 kg/d (HM at 32% dietary starch) among treatments, and was greater for high starch diets and HM treatments compared with low starch diets and DG treatments, respectively. Microbial N flow was greater for high starch diets compared with low starch diets, but was not affected by corn grain treatment. Microbial efficiency was lower for HM compared with DG treatment (39.7 vs. 48.4 g of microbial N/kg of true ruminally degraded OM), but was not affected by dietary starch concentration. Microbial efficiency was positively correlated with rate of passage for OM and starch (r = 0.77 and 0.75, respectively). Rapid passage rate may have decreased microbial turnover in the rumen, enhancing microbial efficiency. Microbial efficiency was negatively correlated with rate of starch digestion (r = -0.55), consistent with the energy spilling theory. However, energy spilling did not appear to be from lack of ammonia or low ruminal pH. Microbial efficiency was not related to ruminal ammonia concentration, daily mean ruminal pH, or minimum ruminal pH. Rate of starch availability and rates of passage for starch and OM from the rumen are important determinants of efficiency of microbial protein synthesis in vivo.     

Degradation of starch in feed concentrates by enzymes,rumen fluid and rumen enzymes

The degradation of starch from various feedstuffs was investigated with rumen fluid, α-amylase, pancreatin and a freeze-dried, cell-free preparation of rumen fluid. Rumen fluid was taken from either a hay-fed cow or a concentrate-fed cow. It was shown that incubations with rumen fluid at a constant pH of 6·5 gave a higher degradation of starch than those with a decreasing pH. The degree of starch degradation varied widely for the 21 feedstuffs investigated. Sorghum, maize and millet degraded slowly whereas tapioca showed fast degradation. Processed feedstuffs showed a higher level of degradation than unprocessed ones. The use of enzymes did not allow an accurate prediction of starch degradation by rumen fluid. However, this was made possible by the use of a freeze-dried, cell-free preparation of rumen fluid. Scanning electron microscopic observations showed that for the degradation of starch granules additional enzymes, present in rumen fluid, are necessary.