安全性复合预混料及日粮电解质平衡对奶牛生产性能的影响

试验结果显示,奶牛生产中应用安全性复合预混料以及对基础日粮进行电解质平衡调节,可显著提高奶牛产奶性能,改善牛奶品质。利用电解质平衡日粮,可提高奶牛产奶量5.60%(P<0.01),提高牛奶密度0.29%;在电解质平衡日粮基础上,使用安全性复合预混料,可进一步提高奶牛产奶量6.26%(P<0.01),提高牛奶密度0.19%;二者综合考虑,可提高奶牛产奶量12.24%(P<0.01),提高牛奶密度0.49%。     

Effects of Silage Fermentation and Post-ruminal Casein Supplementation in Lactating Dairy Cows: 1—Diet Digestion and Milk Production

Two silages were prepared from the first-cut sward of timothy-meadow fescue and wilted to a dry matter (DM) content of 300 g kg^-1. One was ensiled with the addition of a formic-acid-based additive (4 litres formic acid (FA) per tonne) and the other with the addition of a bacterial inoculant (LAB) at a rate of 5×10⁶ colony forming units g^-1. Both silages were well preserved, but the extent of fermentation was greater in LAB-silage than in FA-silage as indicated by a lower concentration of water soluble carbohydrates (68 vs 177 g kg^-1 DM) and a higher concentration of lactic acid (147 vs 32 g kg^-1 DM). Four Ayrshire cows were used in a 4×4 Latin square experiment with 21-day periods to study the effects of silage fermentation and postruminal casein supplementation on silage intake, nutrient supply and milk production. The four treatments were FA-silage without casein (FA-0), LAB-silage without casein (LAB-0), FA-silage with casein (FA-C) and LAB-silage with casein (LAB-C). Both silages were given ad libitum with 8 kg day^-1 of barley without or with 400 g day^-1 of casein infused into the duodenum. Organic matter digestibility was lower (0·723 vs 0·753; P<0·01) for FA-silage than for LAB-silage. Cows offered FA-silage had a higher molar proportion of acetate and a lower proportion of propionate in ruminal fluid than cows offered LAB-silage. Microbial protein synthesis estimated from the output of purine derivatives in urine was greater (288 vs 260 g N day^-1; P<0·05) for cows given FA-silage compared with LAB-silage. Feeding LAB-treated silage tended (P<0·10) to decrease silage DM intake compared with FA-treated silage (10·61 vs 11·77 kg DM day^-1). Silage composition did not affect significantly milk yield or milk composition. Casein infusion increased milk yield (25·1 vs 27·1 kg day^-1; P<0·05), milk protein content (32·4 vs 33·8 g kg^-1; P<0·05) and protein yield (808 vs 905 g day^-1; P<0·01). The responses were similar for both silages. © 1997 SCI.     

Forage Growth and Performance of Grazing Dairy Cows Fed Concentrates with or Without Sodium Bicarbonate

Groups of 12 and 13 Holstein cows grazed rotarionally on mixtures of grasses and red clover. Cows were 28 to 150 days into lactation at start of the experiment. They were fed concentrate at 1 kg/3 kg of 4% fat-corrected milk with or without 1.9% sodium bicarbonate in a switchover trial of two 8-wk periods. Forage growth and composition, amounts available for grazing, and average intake were measured by subsamples clipped prior to and after each grazing and by use of cages placed in the field. Milk yields averaged 29.9 kg daily by cows on each treatment. Milk fat percentage decreased moderately when cows first went to pasture but were not different during the trial at 3.24 and 3.27% on control and buffer treatments. Milk protein percentages, proportions of ruminal volatile fatty acids, and body weight gains did not differ with treatment. Available forage exceeded 17 kg dry matter per cow daily. It was of good quality, as indicated by crude protein contents of 19 and 22%, acid detergent fiber less than 35%, and 67 to 70% in vitro digestibility. Average intake of forage dry matter, measured by the sward cutting technique, was 12.6 kg per cow daily over the 16 wk.     

By-Product Feeds for Lactating Dairy Cows: Effects of Cottonseed Hulls,Sunflower Hulls,Corrugated Paper,Peanut Hulls,Sugarcane Bagasse,and Whole Cottonseed with Additives of Fat,Sodium Bicarbonate,and Aspergillus oryzae Product on Milk Production

In Experiment 1, Holstein cows (32) fed diets in three 28-day periods were used to evaluate a 3 × 2 × 2 factorial arrangement of fiber sources (sunflower hulls, pelleted cottonseed hulls, and pelleted undelinted cottonseed hulls at 35% of dry matter), fat (0 or 2.5%). and sodium bicarbonate (0 or 1.0%). Sixteen cows also received Aspergillus oryzae product (56.7 g/day) continuously. Sunflower hulls decreased daily intake (19.4 versus 25.1 kg), milk (23.3 versus 26.5 kg), milk protein (2.85 versus 2.95%), and body weight change (?.08 versus .90 kg), but milk fat percent was higher (3.54 versus 3.32%). Sunflower hulls depressed digestibility of dry matter, organic matter, and acid detergent fiber. Added fat reduced milk fat and protein percents. Experiment 2 evaluated fiber sources (20% ground corrugated cardboard boxes, combination of 10% cardboard and 10% peanut hulls, or 30% cottonseed hulls), animal fat (0 or 2.5%), sodium bicarbonate (0 or .75%), and condensed molasses solubles by-product from rum distilling (0 or 10%). Corrugated boxes effected lowest intake (18.0 kg/day), cottonseed hulls highest intake (23.5 kg/day), and combination intermediate (20.2 kg/day). Added fat depressed fat percent. Condensed molasses solubles lowered milk yield but increased milk fat percent (3.76 versus 3.30), molar percent of acetic acid, and ratio of acetic to propionic. In two other experiments whole cottonseed (12.5 or 15% of dry matter) with corn silage, pelleted steam pressure treated sugarcane bagasse, or cottonseed hulls increased milk yield but decreased milk fat percent, especially with pelleted bagasse.     

Effect of Shredding Alfalfa on Cellulolytic Activity,Digestibility, Rate of Passage,and Milk Production

A series of trials was performed with sheep and goats to compare mechanically shredded with conventionally (control) harvested alfalfa hay. Shredded hay tended to contain less CP and more cell wall constituents than the control; digestibility of NDF in vitro also was increased by shredding. Intake of DM and digestibilities of NDF and ADF were increased in sheep fed shredded hay. Digestibilities of DM and CP were similar between treatments. Total tract digestibilities determined using acid detergent lignin and Yb as internal and external markers were similar to those obtained by total collection. There was no effect of shredding on rate of passage and total mean retention time of hay in the digestive tract of sheep. Ruminal pH and VFA were not altered by shredding of hay. However, production of 4% FCM and milk protein content was increased in goats fed shredded hay. Shredded hay suspended in the rumen in situ had higher particle-associated carboxymethylcellulase activity throughout the incubation period than did control hay. The enzyme activity was maximal at 6 h and declined thereafter for both hays. The pattern of particle-associated carboxymethylcellulase activity was similar to that of NDF digestion in vitro.     

Influence of Amount of Feed Intake and Forage Physical Form on Digestion and Passage of Prebloom Alfalfa Hay in Dairy Cows

Six Holstein cows were fed prebloom alfalfa hay in long, chopped, and pelleted form (60:40 hay:grain ratio) in a replicated 3 × 3 Latin square design (21-d periods) conducted in early (wk 3 to 11) and middle (wk 20 to 32) lactation and during the dry period to attain three feed intakes for determination of digesta kinetics. Dry matter intakes averaged 3.75, 2.93, and 1.95% of body weight across intakes. There was no effect of forage physical form on intake or milk production. Chewing activity, ruminal fermentation patterns, and milk fat percent were similar for long and chopped hay treatments. Digestibility of organic matter was reduced 7.9% at high versus low intake and 3.2% when pelleted rather than long hay was fed. Ruminal retention time of ytterbium applied to hay declined with increasing feed intake. There was no effect of chopping or grinding on rumen dry matter fill or retention time of ytterbium applied to hay. Effects of forage physical form on retention time and ruminal fill appear small when low fiber alfalfa is fed. Digestibility depression associated with fine grinding of high quality alfalfa was related to depressed ruminal digestion rate. Digestibility depression at high intake was related to shortened ruminal residence time.     

Effects of Body Condition and Protein on Milk Fat Depression in Early Lactation Dairy Cows

Twenty multiparous and 16 primiparous Holstein cows were fed either a high energy or low energy diet during the dry period to achieve different degrees of body condition. Three weeks postpartum, cows were randomly assigned to either a high protein (23% CP) or a low protein (14.5% CP) diet. The diet contained 21% ADF during wk 3 through 6 postpartum and lowered to 9% ADF during wk 7 through 14 postpartum to depress fat test. Cows fed the low energy prepartum diet had less fat depression when fed the high protein postpartum diet compared with the low protein diet. Milk fat depression was more severe for all cows fed the high energy prepartum diet. Depression in milk fat percentage for multiparous cows was 30.8, 10.2, 34.5, and 26.0% for high energy-high protein, low energy-high protein, high energy-low protein, and low energy-low protein groups, respectively. For primiparous cows, milk fat depression was 37.3, 24.1, 37.0, and 34.6%. After the fiber change, depression in acetate to propionate ratio was less for multiparous cows fed high protein than for those fed low protein. Prepartum energy did not influence acetate to propionate ratio depression that resulted from the fiber change.     

The Effect of Inclusion of Naked Oats in the Concentrate Offered to Dairy Cows on Milk Production,Milk Fat Composition and Properties

Dairy cows in early or mid-lactation were offered naked oats- or barley-based concentrates in addition to ad libitum access to grass silage in a continuous design experiment of 10 weeks duration. Concentrates were formulated on an isonitrogenous basis and contained either 500 g barley or 565 g naked oats kg⁻¹ concentrates as the principal energy source in the concentrate. Concentrate type had no effect on silage intake, milk yield or milk protein concentration. However, nitrogen and modified acid detergent fibre digestibility were significantly reduced by inclusion of naked oats and this was reflected in a significant reduction in milk fat concentration. Milk fat from early lactation cows on the naked oats diet contained the highest proportion of unsaturated and the lowest proportion of saturated fatty acids. Sensory and instrumental analyses determined that this milk fat produced the softest, most spreadable butter. This was supported by solid fat content results. The degree of change in milk fat composition due to diet was similar irrespective of stage of lactation but milk fat compositions with the control treatment differed with stage of lactation. Dietary effects were established by the end of the first week of the trial and persisted for the 10-week trial period.     

碳酸氢钠对组织化小麦蛋白体外消化特性的影响

近年来,基于组织化植物蛋白的植物肉受到越来越多的关注。有关植物肉的蛋白质消化特性还不明确。碳酸氢钠是组织化蛋白制备中常用的添加剂。为了探究碳酸氢钠对组织化蛋白的纤维结构和蛋白质消化特性的影响,制备了含0、0.05%和0.10%（质量分数,以干粉质量计）碳酸氢钠的组织化小麦蛋白。通过测定样品的堆积密度、质构特性、组织化度、微观结构和蛋白质分子间相互作用力分析样品的纤维结构特性。结果表明,随着碳酸氢钠质量分数由0增加到0.1%,组织化小麦蛋白的堆积密度、硬度和组织化度逐渐减小,其纤维结构更加纤细,纤维之间的间隙更多。经过体外口腔和胃消化阶段后,3种组织化小麦蛋白的食糜粒径均随碳酸氢钠质量分数的增大而增大（P>0.05）;在模拟小肠消化结束后,3种样品的消化产物粒径接近（P>0.05）。胃消化30 min时,蛋白质电泳图谱中,3组样品中相对分子质量小于14 300的蛋白质条带颜色随着碳酸氢钠质量分数的增加而变浅。在体外消化结束后,消化食糜中可溶性氮质量分数随碳酸氢钠质量分数的增大而增大（P<0.05）。这些结果表明,随着碳酸氢钠质量分数的增大,组织化小麦蛋白中蛋白质的消化速...     

Effects of Nutrient Additives and Sodium Hydroxide on Ensiling Characteristics and In Vitro Fiber Digestion Kinetics of Dairy Cattle Waste-Energy Feedstuff Mixtures

Dairy waste fiber was mixed in ratio 1:1 (dry matter basis) with ground alfalfa hay, chopped cornstalks, chopped whole corn plant, or ground corn. Prior to ensiling, mixtures received either no additive, dry cane molasses at 5% of dry matter, urea at 1% of dry matter, dry cane molasses at 5% plus urea at 1% of dry matter, sodium hydroxide at 3.3% of dry matter, or sodium hydroxide at 3.3% plus urea at 1% of dry matter. Lactate concentration of silages increased progressively in those receiving alkali, urea, or molasses. Sodium hydroxide treatment tended to increase unavailable nitrogen of silages. Molasses increased a) digestion rate of acid detergent fiber in alfalfa: dairy waste fiber, and b) digestion coefficients of corn silage: and corn:dairy waste fiber silages. Urea additions resulted in less digestion of stalklage:dairy waste fiber. Addition of soluble nitrogen and energy together often improved digestion over addition of either one alone. Sodium hydroxide was effective in increasing a) digestion of certain fiber fractions of all silages except corn silage: dairy waste fiber and b) digestion rate of corn silage:dairy waste fiber hemicellulose. Addition of urea to alkali-treated corn silage:dairy waste fiber increased digestion of neutral detergent fiber and hemicellulose beyond that of alkali-treated mixtures alone.     

Effects of Altering Milk Production and Composition by Feeding on Multiple Component Milk Pricing Systems

Data representing 1105 cows were obtained from published scientific reports to estimate the extent to which changes in feeding may affect the composition of milk and the production of milk protein and milk fat. Changes in milk pricing systems were also related to dairy cattle feeding practices that dairy producers may profitably implement. Regression equations were derived to estimate the transfer of gross energy in feed and gross energy in crude protein of feed into milk fat and milk protein. Feeding rations that contained 59% concentrate increased dry matter and crude protein intakes compared to feeding rations that contained 49% concentrate. Feeding higher energy rations also resulted in increased production of milk, milk fat, and milk protein and returned a greater profit over feed costs when milk was priced using each of four milk pricing systems. An increase in milk production, rather than a change in composition of milk components, accounted for most of the economic gain.     

Effects of Sodium Bicarbonate,Magnesium Oxide,and a Commercial Buffer Mixture in Early Lactation Cows Fed Hay Crop Silage

Sixteen early lactation Holstein cows fed 70% concentrate: 30% hay crop silage were used to determine effects of .7% sodium bicarbonate, .7% sodium bicarbonate plus .28% magnesium oxide, or 1.8% commercial buffer mixture (total ration dry basis). This mixture contained a variety of buffers, alkalis, and other compounds known to affect milk production or composition in some circumstances. Buffers did not affect dry matter intake, milk yield, or milk composition but decreased efficiency of milk production. Ruminal fluid pH was not affected, but fecal pH and digestibilities of dry matter, organic matter, energy, acid detergent fiber, and cellulose were increased by the mixed buffers compared with sodium bicarbonate alone. Total ruminal volatile fatty acid concentration was reduced by buffers. Compared with sodium bicarbonate alone, mixed buffers increased ruminal ammonia concentration, acetate proportion, and acetate:propionate ratio and decreased proportions of propionate and butyrate. Valerate was reduced by all three buffers. Ruminal volume and liquid dilution rate were unaffected, but buffers increased total fluid outflow from the rumen. Higher amounts of buffers or alkalis may be necessary to offset low rumen pH and affect production with hay crop silage-based diets.     

The Effect of Silage and Concentrate Type on Intake Behavior, Rumen Function, and Milk Production in Dairy Cows in Early and Late Lactation

The objective of this experiment was to evaluate the effect of feeding total mixed rations (TMR) that differ in structural and nonstructural carbohydrates to dairy cows in early and late lactation on short-term feed intake, dry matter intake (DMI), rumen fermentation variables, and milk yield. A 5 × 5 Latin square experiment with 15 dairy cows was repeated during early and late lactation. The 5 treatments were a TMR with (all on dry matter basis) 55% roughage (a 50:50 mixture of corn silage and grass silage) and 45% concentrate (a 50:50 mixture of concentrate rich in structural carbohydrates and concentrate rich in nonstructural carbohydrates; treatment CON), a TMR with the concentrate mixture and 55% grass silage (RGS) or 55% corn silage (RCS), and a TMR with the roughage mixture and 45% of the concentrate rich in structural carbohydrates (CSC) or the concentrate rich in nonstructural carbohydrates (CNS). Meal criteria, determined using the Gaussian-Gaussian-Weibull method per animal per treatment, showed an interaction between lactation stage and treatment. Feed intake behavior variables were therefore calculated with meal criteria per treatment-lactation stage combination. Differences in feed intake behavior were more pronounced between treatments differing in roughage composition than between treatments differing in concentrate composition, probably related to larger differences in chemical composition and particle size between corn silage and grass silage than between the 2 concentrates. The number of meals was similar between treatments, but eating time was greater in RGS (227 min/d) and lesser in RCS (177 min/d) than the other treatments. Intake rate increased when the amount of grass silage decreased, whereas meal duration decreased simultaneously. These effects were in line with a decreased DMI of the RGS diet vs. the other treatments, probably related to the high neutral detergent fiber (NDF) content. However, this effect was not found in CSC, although NDF content of the TMR, fractional clearance rate of NDF, and fractional degradation rate of NDF was similar between CSC and RGS. Rumen fluid pH was lesser, and molar proportions of acetic acid and of propionic acid were lesser and greater, respectively, in RCS compared with all other diets. Milk production did not differ between treatments. There was no effect of type of concentrate on milk composition, but diet RCS resulted in a lesser milk fat content and greater milk protein content than diet RGS. Lactation stage did affect short-term feed intake behavior and DMI, although different grass silages were fed during early and late lactation. The results indicate that short-term feed intake behavior is related to DMI and therefore may be a helpful tool in optimizing DMI and milk production in high-production dairy cows.     

不同锌源对奶牛产奶量和乳品质的影响

本试验采用3×3拉丁方设计,将9头中国荷斯坦奶牛分为3组,分别饲喂对照组基础日粮,补加蛋氨酸锌日粮(锌含量400mg),补加氧化锌日粮(锌含量400mg),研究补饲不同锌源对奶牛产奶量及乳品质的影响。结果表明,不同来源的锌对奶牛产奶量均有不同程度提高,蛋氨酸锌提高幅度大于氧化锌,但差异不显著(p>0.05);对乳脂率无明显影响;补锌可增加乳中锌的含量,蛋氨酸锌比氧化锌明显(p<0.05)。     

不同长度玉米秸秆青贮对奶牛生产性能的影响

将玉米秸秆以10、26 mm两种不同长度切碎后青贮,分别以直接和全混合日粮(TMR)揉碎两种形式饲喂奶牛进行比较研究.结果表明:两种切碎长度对玉米秸秆青贮质量无明显影响;但无论采用何种饲喂方法,将切碎长度为26 mm的青贮玉米秸秆饲喂给奶牛,奶牛产奶量提高,胎衣不下减少,空怀母牛降低,各种疾病发生减少;同时切碎长度增加还可以提高青贮劳动效率.     

Effects of High Amounts of Dietary Choline Supplementation on Duodenal Choline Flow and Production Responses of Dairy Cows,

At low amounts of supplementation, dietary choline as choline chloride is rapidly degraded in the rumen. Two experiments were conducted to investigate whether the bacterial choline degradation in the rumen of dairy cows could be overwhelmed. Holstein cows were fed total mixed rations containing 40% corn silage and 60% concentrate on a DM basis with treatments of 0, 10, and 20 g added choline/kg ration DM fed in a Latin square design. In Experiment 1, using three ruminally and duodenally cannulated, late lactation cows, increasing dietary choline intake from 23 to 326 g/d increased duodenal choline flow from 1.2 to 2.5 g/d, indicating a very low recovery of added dietary choline. In Experiment 2, with 18 midlactation cows, increasing choline from 18 to 282 g/d reduced feed intake from 18.4 to 16.7 kg/d. Milk composition was unaffected, and milk production tended to decrease with increasing dietary choline. High amounts of added choline reduced feed intake and did not improve milk production of cows.