特香型大曲中纤维素酶、半纤维素酶、蛋白酶、酯化酶活力变化规律的研究

跟踪检测了不同存储期特香型大曲中纤维素酶、半纤维素酶、蛋白酶、酯化酶活力,并通过综合分析比较得出结论：储存3~4个月的大曲,其纤维素酶、半纤维素酶、蛋白酶、酯化酶的活力均达到最好状态,从而为大曲存储期和相关酶活力的质量标准制订提供了有力的理论依据。     

纤维素酶和半纤维素酶改性胡萝卜纤维的研究

以胡萝卜渣中的纤维为原材料,研究纤维素酶和半纤维酶对胡萝卜纤维的长度、宽度以及还原糖浓度和聚合度的影响,并对在胡萝卜纤维改性过程中纤维素酶和半纤维酶协同作用的机理进行探讨。结果表明,纤维素酶和半纤维素酶复合使用比单一酶对胡萝卜纤维改性效果明显。在两者的协同作用下,可以改善纤维表面的细纤维化,提高纤维的酶解产率,降低纤维的聚合度。     

纤维素酶和半纤维酶对纤维改性的研究进展

纤维素酶、半纤维素酶和纸浆纤维作用,产生表面改性,可以降低纸浆打浆能耗,提高纸浆滤水性能等。概述了近20年来纤维素酶、半纤维素酶改性的研究及其应用。     

纤维素酶处理对棉织物染色性能的影响

阐述了纤维素酶减量的作用原理，分析比较了棉织物先用纤维素酶处理，后用活性染料和直接染料染色；或先用活性染料和直接染料染色，再用纤维素酶处理后，棉织物染色性能的变化情况。通过单因素试验，优化酶处理的工艺条件为：酶用量2％(owf)，pH值5．5，温度60℃，浴比1：20，时间45min。     

酿酒酵母对泌乳奶牛生产性能 、健康及经济效益影响的大群试验研究

研究酿酒酵母对改善牛只健康、提升乳品质、增加经济效益的作用效果。选择荷斯坦泌乳奶牛2 480头,以添加酿酒酵母前连续15 d各项指标值作为试验前水平,以添加酿酒酵母后20 d内各项指标值作为试验后水平,共计35 d,试验期每头牛添加酿酒酵母50 g/d。每天统计大群干物质采食量、乳指标、产奶量及牛只发病情况。结果显示,添加50 g/(头·d)酿酒酵母,产奶量增加0.59 kg/d(P0.05),乳脂率提升0.07个百分点(P0.05)。每头牛每天多收益2.46元。结果表明,酿酒酵母对提高泌乳奶牛产奶量,改善乳品质及牛只健康,提高经济效益方面具有积极作用。     

复合纤维素酶对杨木SGW浆纤维素结晶度和微晶体尺寸的影响

在杨木SGW浆酶改性过程中,伴随酶解的进行,纤维素结晶度缓慢增加。在酶解初期,浆的纤维素结晶度增加的幅度相对较大;在酶解后期,浆的纤维素结晶度增幅较小,并趋于一稳定值。另外,伴随酶解的进行,酶解作用使得纤维微晶体尺寸逐渐减小。这说明杨木SGW浆酶改性主要发生在纤维表面的半纤维素存在区域和纤维素的无定形区域。伴随酶改性的进行,酶改性是从纤维表面逐渐向内扩散,在纤维表面产生“剥皮效应”。     

纤维素酶、半纤维酶及果胶酶提取黄姜色素的研究

通过单因素及正交试验研究了纤维素酶、半纤维素及果胶酶同时添加对黄姜色素提取的影响.复合酶提取黄姜色素的最佳工艺条件为:纤维素酶及半纤维素酶的加量均为6.0 mg/g黄姜粉,果胶酶加量为12.5 mg/g黄姜粉,pH为4.6,于60℃下提取4.0 h.     

饱和脂肪酸对泌乳中期热应激奶牛产奶性能、采食量和能量代谢的影响

研究饱和脂肪酸对泌乳中期热应激奶牛产奶性能、采食量和能量代谢的影响。选择产后150~210 d的中国荷斯坦奶牛48头,采用完全随机区组试验设计,根据产奶量、分娩时间和胎次分为对照组、1.5%和3%饱和脂肪酸试验组。试验期间牛舍最小湿热指数(THI)在72以上。结果显示,日粮添加饱和脂肪酸显著提高奶牛产奶量(P0.05),1.5%与3%脂肪组之间差异不显著;乳脂和总固体产量,3%脂肪组显著高于1.5%脂肪组和对照组(P0.05),1.5%脂肪组显著高于对照组(P0.05)。饱和脂肪酸对DMI无影响,净能和粗脂肪采食量随脂肪添加量而呈线性增加(P0.01)。3%和1.5%脂肪组分别比对照组净能转化率提高5.69%和6.04%;粗蛋白转化率分别提高8.48%和6.20%,体重和体况三组间无差异。血液中NEFA含量,3%脂肪组显著低于对照组(P0.05);血糖、胆固醇、BHBA、胰岛素三组间无差异。饱和脂肪酸可以提高奶牛产奶性能和维持能量平衡,对能量代谢、采食量、体重和体况无明显影响。     

夏季高温季节泌乳奶牛饲喂马铃薯对产乳生产性能的影响

马铃薯又名土豆、地蛋等。它是人们生活中的一种常用蔬菜 ,其营养极为丰富。据测定 ,每 5 0 0ｇ鲜马铃薯含蛋白质8.4ｇ,脂肪 3.1ｇ,碳水化合物 70ｇ ,粗纤维 6 .2ｇ ,钙 4 8ｍｇ,铁4ｍｇ ,胡萝卜素 0 .0 4ｍｇ ,硫胺素 0 .4 4ｍｇ,核黄素 0 .13ｍｇ ,尼克酸 1.8ｍｇ。马铃薯味甘、性平 ,有和胃调中、健脾益气之功效 ,对胃病、便秘等病具有一定的疗效。马铃薯既是一种常用蔬菜 ,又是饲喂奶牛的一种极好的优质多汁块茎类饲料。尤其是在夏季高温季节 ,由于奶牛怕热不怕冷 ,当外界气温高于 2 8℃时 ,就会出现热应激反应 ,从而导致泌乳奶牛食欲低…     

复配纤维素酶组分对酶性能的影响

采用CMC酶活法对复配纤维素酶中的组分山梨醇、苯甲酸钠、氯化钠等试剂进行测试，分析其对酶性能的影响，发现一些组分能促进纤维素酶的催化反应，为纤维素酶的复配及应用提供指导。     

乳酸菌制剂对奶牛泌乳量及乳成分的影响

选择27头经产,产犊30～45d,产奶量相近,胎次相近,体重相近,健康无病的高产奶牛。随机分为3组,1组为基础对照组,2组（A组和B组）为试验组,试验组在基础日粮的水平上添加10g不同型号的乳酸菌制剂,预试期2周,正试期为6周。结果表明,两种乳酸菌对奶牛产奶量和奶成分有不同程度的影响,其中A组奶牛的产奶量比对照组有所增加,且差异显著（P〈0．05）,B组则有所下降;不同型号的乳酸菌制剂对牛乳成分也有不同程度的影响。A组奶牛除乳糖率与对照组相比有所降低外,其他乳成分（乳脂率、蛋白率和非脂固形物）相比对照组均有显著增长（P〈0．05）;B组奶牛其乳脂率呈上升趋势,日蛋白产量及日乳糖产量较对照组有所下降,对其他乳成分无显著影响。乳酸菌A能显著减少乳体细胞数（p〈0.05）。两种乳酸菌所生产牛奶的比重、冰点、酸度与对照组无显著差异。     

枯草芽孢杆菌对奶牛生产及乳脂脂肪酸组成的影响

研究不同枯草芽孢杆菌对奶牛生产性能和乳脂脂肪酸成分的影响。与对照组相比,试验组A和B日产奶量呈增加趋势,乳脂产量、乳脂率显著增加(P<0.05);除B组乳中体细胞数显著增加外,各试验组乳蛋白、乳糖、非脂固形物等指标无显著变化。脂肪酸的组成比例与对照组相比无显著差异(P>0.05)。但在A和B组中,对长链及中短链脂肪酸的合成均可起促进作用。     

Effects of sarcocystosis on milk production of dairy cows

Sixteen multiparous Holstein cows were allotted randomly to four groups of four cows each. Cows in 1 and 2 were uninfected. Those in 3 received 60,000 and those in 4 received 120,000 Sarcocystis bovicanis sporocysts per os approximately 30 days before the expected onset of lactation to produce nonclinical and clinical infections in 3 and 4, respectively. Combined stresses of infection, parturition, lactation, and high ambient temperatures caused all infected cows to develop clinical illness. Clinical signs included fever, anemia, glossitis, myositis, nasal discharge, hypersalivation, anorexia, and hind limb weakness; two cows died and two others were killed in extremis. Six cows in 3 and 4 developed high Sarcocystis-specific immunoglobulin G1 antibody. Uninfected control cows had no clinical signs and no rising concentrations of antibody against Sarcocystis antigen. When lactation began, cows were milked twice daily, and milk production was recorded for 70 consecutive days. All sarcocystis-infected cows (3 and 4) decreased feed intake and milk production compared with uninfected controls. The Wisconsin Mastitis Test on milk production compared with uninfected controls. The Wisconsin Mastitis Test on milk samples at 1, 2, 4, 8, and 12 wk of lactation did not differ among groups.     

Effects of different protein supplements on milk production and nutrient utilization in lactating dairy cows

Sixteen (8 ruminally cannulated) multiparous and 8 primiparous lactating Holstein cows were used in 6 replicated 4 × 4 Latin squares to test the effects of feeding supplemental protein as urea, solvent soybean meal (SSBM), cottonseed meal (CSM), or canola meal (CM) on milk production, nutrient utilization, and ruminal metabolism. All diets contained (% of DM) 21% alfalfa silage and 35% corn silage plus 1) 2% urea plus 41% high-moisture shelled corn (HMSC), 2) 12% SSBM plus 31% HMSC, 3) 14% CSM plus 29% HMSC, or 4) 16% CM plus 27% HMSC. Crude protein was equal across diets, averaging 16.6%. Intake and production were substantially reduced, and milk urea, blood urea, and ruminal ammonia were increased on urea vs. the diets supplemented with true protein. Although intake was lower in cows fed SSBM compared with CM, no differences were observed for milk yield among SSBM, CSM, and CM. Yields of fat and protein both were lower on CSM than on CM, whereas SSBM was intermediate. Milk urea and milk protein contents also decreased when CSM replaced SSBM or CM. Diet did not affect ruminal volatile fatty acids except that isobutyrate concentration was lowest on urea, intermediate on CSM, and greatest on SSBM and CM. Urinary excretion of urea N and total N was greatest on urea, intermediate on SSBM and CM, and lowest on CSM. Apparent N efficiency (milk N/N intake) was lower on the CSM diet than on the SSBM diet. Overall, production and N utilization were compromised when the diets of high-yielding dairy cows were supplemented with urea rather than true protein and the value of the true proteins, from most to least effective, was in the order CM > SSBM > CSM.     

Effects of different transition diets on dry matter intake,milk production,and milk composition in dairy cows

The primary objective of this study was to evaluate the effect on dry matter intake (DMI), milk yield, milk composition, body weight (BW), and body condition score (BCS) change of cows offered diets differing in energy density in the last 4 wk of gestation and in the first 8 wk of lactation. Three diets (grass silage:straw, 75:25 on a dry matter basis (SS), grass silage (S), and grass silage + 3 kg concentrate daily (C)) precalving, and two diets (4 kg [LC] or 8 kg [HC] concentrate daily + grass silage ad libitum) postcalving were combined in a 3 x 2 factorial design. Sixty Holstein-Friesian cows entering their second lactation were blocked according to expected calving date and BCS into groups of six and were then allocated at random to the treatments. Individual feeding started 4 wk prior to the expected calving date and measurements were made until the end of the 8th wk of lactation. Mean DMI differed between each of the precalving treatments (7.4, 8.1, and 9.9 kg/d for SS, S, and C, respectively) in the precalving period. The DMI also differed between SS and C for wk 1 to 8 (13.5 and 14.2 kg/d) postcalving. Postcalving, milk (24.2, 26.2, and 28.2 kg/d), fat (933, 1063, and 1171 g/d), and protein (736, 797, and 874 g/d) yields differed between SS, S, and C, respectively. The BCS changes differed between SS and C (-0.09 and 0.12 of a BCS) in the precalving period and between SS and S compared with C (0.02, 0.06, and -0.26 of a BCS) for wk 1 to 8 postcalving. The BW change differed between SS and S compared with C in both wk 1 to 4 (-0.23, -0.37, and -1.25 kg/d) and wk 1 to 8 (0.18, 0.10, and -0.58 kg/ d) postcalving. The BW and BCS were lower at calving for cows on SS compared with C. The greater amount of concentrate supplement postcalving increased DMI, yields of milk, fat, and protein and decreased BW loss in the first 8 wk of lactation. In conclusion, these results indicate that a greater energy density diet in the final 4 wk of the dry period improves cow production in early lactation.     

Effects of postpartum uterine diseases on milk production and culling in dairy cows

The objective was to quantify the effect of postpartum uterine diseases on milk production and culling. Data from 2,178 Holstein cows in 6 herds enrolled in a randomized clinical trial were used. Milk production data from the first 4 Dairy Herd Improvement Association (DHIA) test-days and culling data from farm records were collected. Retained placenta (RP; ≥24 h after parturition) and metritis [≤20 d in milk (DIM)] were diagnosed by farm managers using standardized definitions. Farms were visited weekly and cows were examined at 35 and 56 (±3) DIM using endometrial cytology (cytobrush device), vaginal discharge scoring (Metricheck device), and measurement of cervical diameter by transrectal palpation. Diagnostic criteria for cytological endometritis (CYTO) and purulent vaginal discharge (PVD) were established based on a detrimental effect on subsequent reproduction. Statistical analyses were performed using linear mixed models, logistic regression models, and Cox proportional hazard models, accounting for the effects of experimental treatments and herd clustering. Milk production and culling were the outcomes. Primiparous and multiparous cows were modeled separately for milk production. Milk production of primiparous cows was unaffected by uterine diseases. The effect of metritis on milk production was variable over time in multiparous cows: it decreased production per cow by 3.7 kg at the first DHIA test, but was not different at later tests. Retained placenta decreased milk production by 2.6 kg/d in multiparous cows through the first 4 DHIA tests. The projected effects of metritis and RP in multiparous cows were reductions of 259 kg and 753 kg over 305 DIM, respectively; these effects were additive. Neither CYTO nor PVD affected milk production. Culling risks at 30 and 63 DIM were unaffected by RP and metritis. Culling hazard up to 300 DIM was unaffected by RP, metritis, CYTO, or PVD, whether or not pregnancy status, milk production, and displaced abomasum were accounted for. Uterine disease decreased pregnancy rate, which was a substantial risk factor for culling; however, if affected cows became pregnant they were not at greater risk of culling.     

Effects of feeding lutein on production performance,antioxidative status,and milk quality of high-yielding dairy cows

This experiment was conducted to determine the influences of supplementing different levels of an additive containing lutein in the diet of Chinese Holstein lactating cows on production performance, antioxidative plasma metabolites, and milk quality. This study was performed on 60 multiparous Holstein dairy cows in peak lactation. The cows were randomly allocated to 1 of 4 homogeneous treatments, with lutein preparation (extracted from marigolds; effective lutein content was 2%) added at levels of 0, 100, 150, and 200 g/d per head, with the actual available amounts being 0, 2, 3, and 4 g of lutein/d per head, respectively. The experiment lasted for 13 wk, with the first week for adaptation. Milk yield and milk compositions were recorded weekly, and milk concentrations of lutein, dry matter intake, and antioxidative blood index were analyzed in the first, fourth, seventh, and thirteenth week of the study. The results showed that adding lutein in the diet had no effect on dry matter intake compared with the control group; however, it slowed down the trend of decline in milk yield, and had a linear incremental effect on milk yield with increasing concentration of lutein. Dietary lutein tended to quadratically increase the percentage of milk fat, and linearly increased milk lactose concentration, with the highest value when treated at 200 g of lutein preparation/d per head, and decreased somatic cell count, with the lowest values when treated with 150 and 200 g of lutein preparation/d per head. The concentration of lutein in milk linearly increased with the incorporation of the additive, with a value of 0.59, 0.70, 1.20, and 1.50 μg/100 mL when treated with 0, 100, 150, and 200 g/d, respectively. Total plasma antioxidant capacity tended to linearly increase in cows fed lutein preparation, whereas plasma superoxide dismutase and glutathione peroxidase activities did not differ significantly. In conclusion, addition of lutein in the diet could improve the production performance and health status of dairy cows.     

Effects of feeding dairy cows different legume-grass silages on milk phytoestrogen concentration

Phytoestrogens are hormone-like substances in plants that can substantially influence human health (positively or negatively), and when fed to dairy cows are partly transferred to their milk. The aim of this study was to investigate the effects of varying the botanical composition and regrowth interval of legume-grass silage on phytoestrogen intake and milk phytoestrogen concentrations. In one experiment, 15 Swedish Red dairy cows were fed 2- or 3-cut red clover-grass silage, or 2-cut birdsfoot trefoil-grass silage. In a second experiment, 16 Norwegian Red dairy cows were fed short-term ley silage with red clover or long-term ley silage with white clover, and the effects of supplementation with α-tocopherol were also tested. High concentrations of formononetin and biochanin A were found in all silage mixtures with red clover. The milk concentration of equol was highest for cows on the 2-cut red clover-grass silage diet (1,494 μg/kg of milk). Because of the metabolism of biochanin A, genistein, and prunetin, their concentrations in milk and the apparent recovery were low. Coumestrol was detected in only short-term and long-term ley silage mixtures, and its milk concentration was low. Concentrations of secoisolariciresinol and matairesinol were higher in 2-cut birdsfoot trefoil-grass and long-term ley silage mixtures, those with legume species other than red clover, and the highest grass proportions. The 2-cut birdsfoot trefoil-grass silage diet also resulted in higher enterolactone concentration than the other diets (226 μg/kg of milk). Lengthening the regrowth interval increased the intake of secoisolariciresinol and decreased the recovery of lignans. Feeding long-term ley silage resulted in higher milk lignan concentrations but lower milk isoflavone concentrations than feeding short-term ley silage. The apparent recovery of all phytoestrogens except prunetin was highest on the 2-cut birdsfoot trefoil-grass silage diet. No effect of α-tocopherol supplementation was observed on milk concentrations of any of the measured phytoestrogens. Variations were observed in milk concentrations of phytoestrogens, especially of equol, among cows, which could not be explained by variations in diet composition or phytoestrogen intake. The results show that milk phytoestrogen concentration is strongly influenced by silage botanical composition, but questions regarding phytoestrogen metabolism remain to be answered.     

Assessment of dietary ratios of red clover and grass silages on milk production and milk quality in dairy cows

Twenty-four multiparous Holstein-Friesian dairy cows were used in a replicated 4 × 4 Latin square changeover design experiment to test the effects of changing from ryegrass (Lolium perenne) silage to red clover (Trifolium pratense) silage in graded proportions on feed intakes, milk production, milk organoleptic qualities, and whole-body nitrogen partitioning. Four dietary treatments, comprising ad libitum access to 1 of 4 forage mixtures plus a standard allowance of 4 kg/d dairy concentrates, were offered. The 4 forage mixtures were, on a dry matter (DM) basis: 1) 100% grass silage, 2) 66% grass silage: 34% red clover silage, 3) 34% grass silage: 66% red clover silage, and 4) 100% red clover silage. In each of 4 experimental periods, there were 21 d for adaptation to diets and 7 d for measurements. There was an increase in both DM intakes and milk yields as the proportion of red clover in the diet increased. However, the increase in milk yield was not as great as the increase in DM intake, so that the efficiency of milk production, in terms of yield (kg) of milk per kg of DM intake, decreased. The concentrations of protein, milk fat, and the shorter chain saturated fatty acids decreased, whereas C18 polyunsaturated fatty acids (PUFA) and long-chain PUFA (C20+) increased as the proportion of red clover in the diet increased. There was little effect of dietary treatment on the organoleptic qualities of milk as assessed by taste panel analysis. There were no effects on the aroma of milk, on aftertaste, or overall liking of the milk. Milk was thicker and creamier in color when cows were fed grass silage compared with red clover silage. The flavor of milk was largely unaffected by dietary treatment. In conclusion, increasing the proportion of red clover in the diet of dairy cows increased feed intakes and milk yields, decreased the concentration of fat and protein in milk, increased PUFA for healthiness, and had little effect on milk organoleptic characteristics.     

The effect of lameness on milk production in dairy cows

Data were collected prospectively for 1.5 yr on two New York dairy farms to investigate the effect of lameness on milk production. The numbers of study cows (percentages treated at least once for lameness) in each herd were 1796 (52%) and 724 (40%), respectively. Lame cows were identified and treated by farm employees or a professional hoof trimmer. Weekly averages of total milk production per day were recorded based on automated milk weight measurements at each milking. The effect of lameness on milk production was analyzed separately for each herd using repeated measures ANOVA. In both herds, milk production decreased significantly for cows diagnosed lame. Milk production was 1.5 kg/d lower > or = 2 wk after lameness compared with cows that had not yet been diagnosed lame in the current lactation in the larger herd. In the second herd, milk production of lame cows was 0.8 kg/d lower in the first and second wk after lameness and 0.5 kg/d lower > or = 3 wk after diagnosis. The decrease in milk production associated with lameness was larger for cows in second or greater lactation and for more severe cases. In one herd, the decrease in milk production was greater for cows with sole ulcers or foot abscesses than for foot rot or foot warts. Cows with abscesses or foot rot tended to have larger decreases in milk production in the other herd. The inconsistent results between farms may have resulted from differences in the relative frequencies of specific causes of lameness in the two herds and in the way lame cows were identified and defined for the study.