6种饲料原料瘤胃降解特性和瘤胃非降解蛋白质的小肠消化率

本试验旨在研究新疆地区玉米青贮、棉籽壳、苜蓿草粉、苜蓿干草、葡萄籽粕、蕃茄酱渣6种奶牛饲料原料的瘤胃降解特性和瘤胃非降解蛋白质(RUP)的小肠消化率(Idg)。选用3头装有永久性瘤胃瘘管的泌乳荷斯坦奶牛,采用尼龙袋法和改进三步体外法测定饲料原料的干物质(DM)、粗蛋白质(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的瘤胃降解特性以及RUP的Idg和小肠可消化粗蛋白质(IDCP)含量。结果表明:1)苜蓿草粉和玉米青贮的DM有效降解率最高,显著高于次之的苜蓿干草、番茄酱渣(P0.05),葡萄籽粕、棉籽壳最低,显著低于其他原料(P0.05);CP有效降解率为番茄酱渣苜蓿草粉玉米青贮苜蓿干草棉籽壳葡萄籽粕,各原料间差异显著(P0.05);NDF有效降解率为玉米青贮苜蓿草粉棉籽壳苜蓿干草番茄酱渣葡萄籽粕,各组饲料原料间差异显著(P0.05);ADF有效降解率为玉米青贮棉籽壳苜蓿干草番茄酱渣苜蓿草粉葡萄籽粕,各组饲料原料间差异显著(P0.05)。2)苜蓿草粉RUP的Idg和IDCP含量最高,Idg显著高于依次降低的苜蓿干草、玉米青贮、番茄酱渣、葡萄籽粕、棉籽壳(P0.05),IDCP含量与苜蓿干草差异不显著(P0.05),显著高于依次降低的玉米青贮、番茄酱渣、葡萄籽粕、棉籽壳(P0.05)。综上所述,不同饲料原料具有不同的瘤胃降解特性,进入小肠IDCP的含量也不同。玉米青贮的DM、NDF和ADF在瘤胃的有效降解率较高,苜蓿草粉RUP的Idg较高,苜蓿草粉和苜蓿干草的IDCP含量较高。     

常规与非常规粗饲料在奶牛瘤胃中的降解特性研究

旨在探讨非常规粗饲料(玉米芯、毛豆荚壳)与奶牛常用粗饲料(苜蓿干草、玉米青贮)在奶牛瘤胃中的降解规律,试验选用3只装有永久性瘤胃瘘管的荷斯坦奶牛,采用尼龙袋法测定4种粗饲料的干物质(DM)、粗蛋白(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的瘤胃降解规律。结果表明:1)苜蓿干草和毛豆荚壳的CP含量分别为17.55%和11.10%,且苜蓿干草显著高于毛豆荚壳(P<0.05);玉米芯和玉米青贮的CP含量分别为2.97%和8.41%,且玉米芯显著低于玉米青贮(P<0.05);玉米芯的NDF和ADF含量显著高于其他3种粗饲料(P<0.05),达到79.98%和43.35%。2)苜蓿干草的DM有效降解率最高(P<0.05),由高到低依次为苜蓿干草、毛豆荚壳、玉米青贮和玉米芯。毛豆荚壳的CP有效降解率显著高于其他3种粗饲料(P<0.05),由高到低依次为毛豆荚壳、苜蓿干草、玉米青贮和玉米芯。苜蓿干草的NDF有效降解率显著高于毛豆荚壳(P<0.05),玉米青贮和毛豆荚壳无显著差异(P>0.05);玉米芯的ADF有效降解率最高(P<0.05),苜蓿干草、玉米青贮和毛豆荚壳无显著差异(P>0.05)。综上所述,玉米芯和毛豆荚壳可作为非常规粗饲料资源加以开发利用。     

奶牛常用蛋白质饲料和粗饲料的瘤胃降解特性研究

本研究旨在评定不同蛋白质饲料(豆粕、双低菜籽粕、膨化大豆、玉米蛋白粉、棉籽粕)和粗饲料(苜蓿干草、全株玉米青贮、燕麦草、苜蓿青贮、羊草)的营养价值,并研究其奶牛瘤胃降解特性.选择5头安装永久性瘤胃瘘管的健康荷斯坦牛,采用尼龙袋评定法评定饲料瘤胃有效降解率和动态降解率.结果表明:1)各蛋白质饲料干物质(DM)含量差异不显...     

Evaluation of alfalfa-corn cob associative action. II. Comparative tests of alfalfa hay as a source of ruminal degradable protein

The effect of ruminal degradable protein source in roughage diets on nutrient digestibility and animal growth was evaluated in two trials using lambs. In trial 1, two qualities of alfalfa and smooth brome hays replaced 0, 15, 30 or 100% of an ammonia (NH3)-treated corn cob negative control diet in a digestion trial using 26 mixed breed wethers (31.8 kg). Fifteen or 30% inclusion of hay increased (P less than .01) dry matter (DM) intake, regardless of hay type or quality. Cell wall intake was highest for 100% high quality brome hay. Positive associative action on digestibility of DM and cell walls occurred with 30% of each hay tested when diets were fed ad libitum. Measured at equal intakes, DM and cell wall digestibilities were affected by forage type X level and forage quality X level interactions (P less than .01), which showed that the magnitude of associative action was greater for 30% of high vs low quality and alfalfa vs brome hay, respectively. Magnitude of associative response on cell wall digestibility was more highly correlated to degradable N (r = .88) than cell solubles (r = .64) content of hay. In trial 2, 72 young growing lambs were allotted to three sources of supplemental ruminal degradable N (NH3, casein, corn steep liquor) superimposed upon two levels of alfalfa hay (0 or 30% of diet DM). Diets containing 0% alfalfa were supplemented with ruminal escape protein equivalent to that supplied by 30% alfalfa hay.(ABSTRACT TRUNCATED AT 250 WORDS)     

肉牛常见饲料干物质和蛋白质瘤胃降解特性和小肠消化率研究

[方法]选用装有瘤胃瘘管和小肠瘘管的肉牛作为试验动物,尼龙袋法测定肉牛常见饲料干物质(DM)和粗蛋白(CP)的瘤胃降解特性和小肠消化率。[结果]结果表明,DM瘤胃有效降解率由高到低为玉米粉、麦麸、苜蓿干草、豆粕、菜籽粕、玉米青贮、醋糟、白酒糟;CP瘤胃有效降解率由高到低为苜蓿干草、麦麸、豆粕、醋糟、玉米粉、玉米青贮、菜籽粕、白酒糟;DM小肠消化率由高到低为豆粕、菜籽粕、玉米粉、白酒糟、醋糟、麦麸、苜蓿干草、玉米青贮;CP小肠消化率由高到低为豆粕、菜籽粕、玉米粉、苜蓿干草、麦麸、白酒糟、玉米青贮、醋糟。[结论]试验表明,不同饲料瘤胃降解特性不同,为小肠提供过瘤胃可消化蛋白的能力不同,且饲料的DM小肠消化率小于CP小肠消化率。     

Effect of exogenous fibrolytic enzyme on ruminal fermentation and digestibility of alfalfa and rye-grass hay fed to lambs

This experiment was carried out to study the effect of a directly fed exogenous fibrolytic enzyme on intake and digestion of DM, OM, protein, NDF, ADF, and hemicellulose of alfalfa and ryegrass hay by sheep. Four diets were randomly assigned to four ruminally cannulated lambs using a 4 x 4 Latin square design, repeated in time, with a factorial arrangement (2 x 2) of diets: 1) alfalfa hay; 2) alfalfa hay + exogenous fibrolytic enzymes (enzyme); 3) ryegrass hay; and 4) ryegrass hay + enzyme. Lambs consumed more DM and OM from alfalfa than from ryegrass hay (P < 0.001). The ADF intake was not different between the hays, but NDF intake was lower for alfalfa (P < 0.001). For both hays, the enzyme increased intake of DM (P < 0.01), as well as OM and CP (P < 0.05); however, NDF and ADF intake were not changed. Alfalfa hay had higher apparent digestibility of DM, OM, and CP (P < 0.001), but lower digestibility for NDF, ADF, and hemicellulose. The enzyme increased apparent digestibility of CP, hemicellulose (P < 0.05), and NDF (P < 0.10) for alfalfa. Also, for both hays, the enzyme improved N balance because lambs retained more N (P < 0.05). The enzyme increased (P < 0.05) total VFA concentration (3 and 6 h) for both hays. Results from this trial indicate that directly fed exogenous fibrolytic enzymes may change ruminal fermentation, intake, and digestibility of forages with different nutritive value.     

Effects of wet corn gluten feed and intake level on diet digestibility and ruminal passage rate in steers

Twelve ruminally cannulated Jersey steers (BW = 534 kg) were used in an incomplete Latin square design experiment with a 2 x 2 factorial arrangement of treatments to determine the effects of wet corn gluten feed (WCGF) and total DMI level on diet digestibility and ruminal passage rate. Treatments consisted of diets formulated to contain (DM basis) steam-flaked corn, 20% coarsely ground alfalfa hay, and either 0 or 40% WCGF offered once daily for ad libitum consumption or limited to 1.6% of BW (DM basis). Two consecutive 24-d periods were used, each consisting of 18 d for adaptation, 4 d for collection, and a 2-d in situ period. Rumens of all steers were evacuated once daily at 0, 4, 8, and 12 h after feeding. Chromic oxide (10 g/[steer*d]) was fed as a digestibility marker, and steers were pulse-dosed with Yb-labeled alfalfa hay to measure ruminal particulate passage rate. Dacron bags containing 5 g of steam-flaked corn, WCGF, or ground (2-mm screen) alfalfa hay were placed into the rumens of all steers and removed after 3, 6, 12, or 48 h. Wet corn gluten feed increased percent apparent total-tract digestion of OM (P < 0.01), NDF (P < 0.01), and starch (P < 0.03), decreased (P < 0.01) ruminal total VFA concentration, increased (P < 0.01) ruminal NH3 concentration, and increased (P < 0.01) ruminal pH. Wet corn gluten feed also increased (P < 0.01) ruminal passage rate of Yb. Limit feeding decreased (P < 0.01) percent apparent total-tract digestion of both OM and NDF, ruminal total VFA concentration (P < 0.01), and ruminal fill (P < 0.01), but increased (P < 0.01) ruminal NH3 concentration. Apparent total-tract digestion of starch was not affected (P = 0.70) by level of DMI. A DMI level x hour interaction (P < 0.01) occurred for ruminal pH. Limit feeding increased ruminal pH before and 12 h after feeding, but decreased ruminal pH 4 h after feeding compared with diets offered ad libitum. A diet x DMI level interaction (P < 0.02) occurred for in situ degradation of alfalfa hay, with dietary addition of WCGF increasing (P < 0.02) the extent of in situ alfalfa hay degradation in steers fed for ad libitum consumption. This study suggests that WCGF increases OM and NDF digestion, and that limit feeding diets once daily might depress OM and NDF digestion, possibly due to decreased stability of the ruminal environment.     

Effects of Saccharomyces cerevisiae on In Vitro Mixed Ruminal Microorganism Fermentation

The objective of this study was to examine the effects of two Saccharomyces cerevisiae feed supplements on the in vitro mixed ruminal microorganism fermentation of ground corn, soluble starch, alfalfa hay, and Coastal bermudagrass hay. In the absence of added substrates, both yeast supplements increased (P<0.05) methane concentrations, whereas concentrations of acetate and propionate were numerically increased. In ground corn incubations, both concentrations (0.35 and 0.73 g/L) of both S. cerevisiae supplements had little effect on final pH or fermentation products. Both concentrations of each S. cerevisiae supplement numerically increased concentrations of acetate and butyrate in soluble starch fermentations. In addition, the 0.73-g/L treatment increased (P<0.10) propionate, and both yeast treatments decreased (P<0.05) acetate:propionate. In vitro DM disappearance of alfalfa hay and Coastal bermudagrass hay did increase over time. However, the addition of both concentrations of each S. cerevisiae supplement had little effect on either the rate or extent of digestion of either forage by mixed ruminal microorganisms. In general, both S. cerevisiae supplements seemed to have similar effects on the in vitro mixed ruminal microorganism fermentation.     

Effects of supplemental silage on forage intake and utilization by steers grazing wheat pasture or bermudagrass

Seven trials were conducted to determine the effects of increasing amounts of silage (corn, wheat or sorghum) on forage intake, gastrointestinal tract fill, fecal output and ruminal flow and degradation of forage by cattle grazing wheat pasture or bermudagrass. In each of 3 yr, 24 steers grazed a common wheat or bermudagrass pasture and were randomly allocated to four treatments (0, .35, .70 or 1.05 kg silage DM.100 kg body weight-1.d-1). Intake and ruminal flow of forage were measured by feeding a single pulse dose of Yb-labeled forage followed by collection of fecal samples for 4 to 5 d and fitting Yb concentrations to a one-compartment, age-dependent model. Ruminal digestion kinetics of wheat forage were estimated in situ using eight ruminally cannulated steers fed 0 or .55 kg sorghum silage DM.100 kg body weight-1.d-1. Supplemental silage decreased wheat forage (P less than .10) and bermudagrass (P less than .01) intake linearly. However, total forage intake of bermudagrass plus silage increased linearly (P less than .05). Each kilogram of added silage DM decreased DM intake of wheat forage by .66 +/- .25 and of bermudagrass by .63 +/- .17 kg. Flow and turnover of wheat forage or bermudagrass were not altered (P greater than .15) by supplemental silage. Silage consumption increased extent of ruminal degradation of wheat forage DM (P less than .05; 63.1 vs 52.5%), indicating a positive associative effect of silage on wheat forage utilization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in ruminal fermentation and protein degradation in growing Holstein heifers from 80 to 250 kg fed high-concentrate diets with different forage-to-concentrate ratios

Six Holstein heifers (initial BW = 65.2 +/- 1.8 kg) fitted with ruminal cannulas were used in a repeated measures trial to assess the effect of age and forage-to-concentrate ratio on ruminal fermentation end products and in situ degradation kinetics of four plant protein supplements (soybean meal, sunflower meal, peas, and lupin seeds). Alfalfa hay also was incubated in situ to estimate NDF degradation. Three experimental periods were conducted at 13, 27, and 41 wk of age. Heifers were fed one of two diets, 12:88 vs. 30:70 forage-to-concentrate ratio (DM basis), offered as total mixed ration on an ad libitum basis. Intakes of DM, OM, CP, NDF, and ADG were not affected (P > or = 0.105) by diet. The 30:70 diet resulted in faster (P = 0.045) fluid passage rate and decreased (P = 0.015) ammonia N concentration compared with the 12:88 diet, but no differences (P > or = 0.244) were detected in ruminal pH and total VFA concentration between diets. The rate of degradation and the effective degradability of N in protein supplements was greater with the 30:70 diet for peas (P < or = 0.008) and lupin seeds (P < or = 0.02), and in the 12:88 diet for sunflower meal (P < or = 0.06). Degradation of NDF of alfalfa hay was low with both diets (18.5 and 23.7 % for 12:88 and 30:70, respectively); however, the rate and extent of DM and NDF degradation were greater (P < or = 0.016) with the 30:70 diet, suggesting a higher cellulolytic activity. Total VFA concentration and the proportion of propionate increased (P < or = 0.035), and the acetate proportion decreased (P = 0.021) with age. Average pH, ammonia N concentration, and passage rates were not affected (P > or = 0.168) by age. Degradation rate and effective degradability of N of sunflower meal, peas, lupin seeds, and of DM of alfalfa hay increased (P < or = 0.08) with age, but degradation kinetics of NDF of alfalfa hay was not affected (P > or = 0.249). The increase in the rate and extent of N degradation with age would suggest an increase in proteolytic activity, and the changes in the fermentation pattern may reflect an increase in amylolytic activity caused mainly by an increase in the gross intake of nonstructural carbohydrates and by adaptation of ruminal microflora after long exposure to these nutrients.     

奶牛常用粗饲料的瘤胃降解规律

本试验旨在研究 ２种苜蓿［黑龙江公农 １号苜蓿、美国安德森（Ａｎｄｅｒｓｏｎ）一级苜蓿］、黑龙江 ２种含杂量不同羊草（杂草率分别为 １０％、３４％）、全株玉米青贮、玉米秸秆青贮和玉米秸秆共 ７种粗饲料的瘤胃降解特性。试验选用 ８头装有永久性瘤胃瘘管的荷斯坦奶牛,采用尼龙袋法评定其干物质（ＤＭ）、粗蛋白质（ＣＰ）和中性洗涤纤维（ＮＤＦ）的瘤胃降解率和有效降解率。结果表明,美国安德森一级苜蓿、全株玉米青贮和黑龙江公农 １号苜蓿三者 ７２ｈＤＭ 降解率差异不显著（Ｐ＞０．０５）,并显著高于其他 ４种粗饲料（Ｐ＜０．０５）,而 ＤＭ有效降解率以美国安德森一级苜蓿最高,并与依次降低的黑龙江公农 １号苜蓿、全株玉米青贮和玉米秸秆青贮差异显著（Ｐ＜０．０５）,羊草与玉米秸秆的 ＤＭ有效降解率显著低于其他粗饲料（Ｐ＜０．０５）。７２ｈＣＰ降解率及有效降解率以美国安德森一级苜蓿最高,且降解率与依次降低的黑龙江公农 １号苜蓿、全株玉米青贮、玉米秸秆青贮、杂草率为 １０％的羊草、玉米秸秆和杂草率为 ３４％的羊草间差异显著（Ｐ＜０．０５）。全株玉米青贮、玉米秸秆青贮 ７２ｈＮＤＦ降解率显著高于其他粗饲料（Ｐ＜０．０５）;而有效降解率以 ２种苜蓿较高,其次为玉米秸秆青贮与全株玉米青贮;降解率和有效降解率最低的均为杂草率为 ３４％的羊草。因此,从 ７种粗饲料在奶牛瘤胃的消化特性来看：１）美国安德森一级苜蓿营养价值最高,杂草率为 ３４％的羊草与玉米秸秆营养价值较低;２）羊草的品质受杂草率的影响;３）青贮能改善玉米秸秆的品质。     

Rumen Degradation Characteristics of Six Types of Common Roughage in Khorchin Beef Cattle in Tongliao City

[Objective] The paper was to study the degradation characteristics of different types of roughage in Khorchin beef cattle. [Method] The nylon bag method was used to determine the rumen degradability of six types of roughage: dry matter(DM), crude protein(CP), neutral detergent fiber(NDF) and acid detergent fiber(ADF). [Result] Among the six types of roughage, alfalfa hay had the highest effective degradability of DM and CP in rumen; followed by alfalfa block, corn silage, leymus chinensis and corn stover, and the effective degradability of rice straw was lowest. In terms of effective degradability of NDF and ADF, alfalfa hay was the most effective, while leymus chinensis was the least effective. [Conclusion]Considering degradation characteristics of six types of roughage in Khorchin beef cattle, alfalfa hay possesses the highest nutritional value, while rice straw has the lowest value.     

Particle size reduction during initial mastication of forages by dairy cattle

Four experiments were conducted with dairy cattle to determine the effects of initial feed particle size and moisture content on particle size of ingested masticates. Three mature Holstein cows were used in either latin square or Youden square designs. Samples of masticated and ingested boli were collected at the cardiac opening through a ruminal fistula between 0 and 5, 5 and 10 and 10 and 15 min after meal initiation. In Exp. 1, masticate log mean particle sizes (LMPS) (ln microns, log normal distribution) were 3.50, 3.53 and 3.50 for corn silage, fine-chopped alfalfa haylage and coarse-chopped alfalfa haylage, respectively. In Exp. 2, boli LMPS for ground, chopped and long alfalfa hay were 3.11, 3.76 and 4.09, respectively. Boli LMPS in Exp. 3 for ground, chopped and long timothy hay were 2.93, 3.12 and 3.03, respectively. Exp. 4 compared the effect of addition of water to produce 30%, 47%, 64% and 82% DM in chopped alfalfa hay. Boli LMPS were 3.66, 3.56, 3.64 and 3.68 for the respective alfalfa hay DM contents. Feed LMPS was not reduced during mastication in Exp. 4, nor were there differences in LMPS due to time after feeding. Boli LMPS was affected by feed particle size of alfalfa hay, but there was no effect of feed particle size on masticate particle size in timothy hay. The magnitude of particle size reduction during mastication appears to be dependent on forage type and is not dependent totally on initial feed particle size and DM content of forages.     

Simultaneous measures of rates of ruminal digestion and passage of feeds for prediction of ruminal nitrogen and dry matter digestion in lactating dairy cows

Three ruminal-cannulated Holstein cows in early lactation were fed three diets, each containing different energy and protein supplements in two consecutive 3 X 3 Latin squares. Each supplement contained a combination of three different feedstuffs (ground corn, soybean meal and wheat mids; corn gluten feed, rolled oats and distiller's dried grains; ground barley, brewer's grains and cottonseed meal). Diets consisted of 30% corn silage, 10% alfalfa hay, 10% alfalfa haylage, 17.7% ground corn plus minerals and vitamins, with the remainder as supplemental feedstuffs individually marked for measurement of ruminal turnover and in situ digestion rates. An extra period at the end of each Latin square was used to measure ruminal turnover and in situ digestion of individual forages. Diet had no effect on dry matter intake or milk yield. Mean fractional turnover (per hour) rate, measured by labeling feedstuffs with cerium, samarium or lanthanum was .044, .048, .049, .043, .047, .046, .050, .047, .049, .037, .046 and .045 for corn, soybean meal, wheat mids, corn gluten feed, oats, distiller's dried grains with solubles, barley, brewer's dried grains, cottonseed meal, alfalfa hay, corn silage and alfalfa haylage (P greater than .1), respectively. In situ-predicted ruminal degradation of N weighted for rate of passage was 61.4, 67.0, 81.5, 74.8, 86.3, 71.0, 75.7, 52.1, 54.2, 60.8, 71.7 and 70.9% for respective feedstuffs (P less than .05). In comparison with mean literature values for in vivo-measured N degradability, mean literature value = 1.172 (in situ predicted) -9.73 (P less than .05, R2 = .51). Results are interpreted to indicate a tendency for overestimating ruminal N degradability by in situ methods in feedstuffs of low degradability, while underestimating degradability in more highly degraded feedstuffs. Estimates were 11 to 17 percentage units lower than literature values for alfalfa hay and haylage and 17 units lower than literature values for distiller's dried grains.     

Effects of diets containing alfalfa hay or barley flour mixed alfalfa silage on feeding behavior, productivity, rumen fermentation and blood metabolites in lactating cows

The effects of barley flour on the fermentation parameters of alfalfa silage and on the productivity of dairy cows were investigated. Alfalfa forage was ensiled either with or without barley flour. Barley flour was soaked in water for 24 h before being mixed with alfalfa (12 kg: 100 kg dry matter bases) at ensiling. Eighteen multi-parous cows were assigned to three equal treatment groups using a completely randomized design. Three isocaloric and isonitrogenous total mixed rations containing alfalfa hay, ordinary alfalfa silage or barley flour mixed alfalfa silage were then prepared. The concentrations of ammonia nitrogen, acetic acid and butyric acid were lower in barley flour mixed alfalfa silage compared to that in ordinary alfalfa silage but the concentration of lactic acid was lower in the ordinary alfalfa silage. Feeding behavior, milk yield and composition, ruminal fermentation and blood metabolites were measured. Although dry matter intake and milk production were not affected, the effect of preparation of alfalfa influenced feeding behavior and rumen fermentation parameters. Cows on alfalfa silage diets spent longer ruminating compared to those fed alfalfa hay. The ruminal ammonia nitrogen and blood urea were affected by ensiling (alfalfa hay versus alfalfa silages) while both parameters were lower in cows fed on barley flour mixed alfalfa silage than those fed on ordinary silage. Although similar blood glucose was recorded for cows fed on alfalfa silages, it was higher in cows fed on alfalfa hay. It is concluded that the addition of barely flour when making alfalfa silage may improve both the fermentation process during ensilage and the ruminal ammonia nitrogen utilization with no significant effects on productivity.     

Amino acid profiles of rumen undegradable protein: a comparison between forages including cereal straws and alfalfa and their respective total mixed rations

Optimizing the amino acid (AA) profile of rumen undegradable protein (RUP) can positively affect the amount of milk protein. This study was conducted to improve knowledge regarding the AA profile of rumen undegradable protein from corn stover, rice straw and alfalfa hay as well as the total mixed ratio diets (TMR) based on one of them as forage source [forage‐to‐concentrate ratio of 45:55 (30% of corn stover (CS), 30% of rice straw (RS), 23% of alfalfa hay (AH) and dry matter basis)]. The other ingredients in the three TMR diets were similar. The RUP of all the forages and diets was estimated by incubation for 16 hr in the rumen of three ruminally cannulated lactating cows. All residues were corrected for microbial colonization, which was necessary in determining the AA composition of RUP from feed samples using in situ method. Compared with their original AA composition, the AA pattern of forages and forage‐based diets changed drastically after rumen exposure. In addition, the extent of ruminal degradation of analysed AA was not constant among the forages. The greatest individual AA degradability of alfalfa hay and corn stover was Pro, but was His of rice straw. A remarkable difference was observed between microbial attachment corrected and uncorrected AA profiles of RUP, except for alfalfa hay and His in the three forages and TMR diets. The ruminal AA degradability of cereal straws was altered compared with alfalfa hay but not for the TMR diets. In summary, the AA composition of forages and TMR‐based diets changed significantly after ruminal exposure, indicating that the original AA profiles of the feed cannot represent its AA composition of RUP. The AA profile of RUP and ruminal AA degradability for corn stover and rice straw contributed to missing information in the field.     

Effect of microbial fermentation on functional specific gravity of small forage particles.

Two experiments were designed to determine the effect of gas production during in vitro digestion on functional specific gravity (FSG) of forage particles. In Exp. 1, FSG of ground alfalfa hay decreased from 1.123 to 1.049 between 3 and 9 h of incubation and increased thereafter to reach a plateau at 1.309 after 30 h of incubation. Gas production peaked at 6 h, but gas associated with particles increased until 9 h of incubation. Gas associated with solid residue was correlated to gas production (r = -.67) but also was influenced by gas holding capacity and rate of escape from the particles. In Exp. 2, measurements were performed on ground alfalfa hay, alfalfa silage, and bromegrass hay containing 42.6, 35, and 66.4% NDF, respectively. Gas production seemed to be related to the amount of readily available substrate. Although at 9 h of incubation more gas was produced by alfalfa silage (.235 mL.min-1.g of DM-1) than by bromegrass hay and alfalfa hay (.087 and .187 mL.min-1.g of DM-1, respectively), gas associated with particles was greater for alfalfa hay (.416 mL/g of DM) than for bromegrass hay and alfalfa silage (.256 and .281 mL/g of DM, respectively). The increase in FSG was more rapid for alfalfa silage than for the hays. After 27 h of digestion, gas associated with particles (milliliters per gram of DM) and FSG were .164, 1.226; .147, 1.235; and .001, 1.467 for bromegrass hay, alfalfa hay, and alfalfa silage, respectively. Gas produced during fermentation delayed the increase in specific gravity of forage particles.(ABSTRACT TRUNCATED AT 250 WORDS)     

燕麦干草与全株玉米青贮不同组合对绵羊瘤胃发酵的影响

本试验旨在明确燕麦干草与全株玉米青贮按不同比例组合对绵羊瘤胃发酵的影响。选用9头体重为(70.24±2.03)kg、体况相似且装有永久性瘤胃瘘管的杂种(美利奴×蒙古羊♀)公羊作为试验动物,按过渡期称重结果分成3组,每组3只。按燕麦干草和全株玉米青贮占粗饲料比例(干物质基础)将饲粮分为A1(100%全株玉米青贮)、A2(50%全株玉米青贮+50%燕麦干草)和A3(100%燕麦干草)3种,3种饲粮精粗比均为35∶65。采用3×3拉丁方设计,进行3期试验,每期22 d(预试期15 d,正试期7 d),正试期最后3 d采样。结果显示:1)与100%全株玉米青贮相比,以50%全株玉米青贮+50%燕麦干草或100%燕麦干草为粗饲料对绵羊瘤胃液p H和总氮浓度平均值没有产生显著影响(P0.05),但显著降低了瘤胃液氨态氮(NH3-N)、尿素氮和血浆尿素氮浓度平均值(P0.05),同时以50%全株玉米青贮+50%燕麦干草为粗饲料还显著提高了瘤胃液蛋白氮浓度平均值(P0.05)。此外,A2组的瘤胃液p H和总氮浓度平均值稍高于A3组,瘤胃液蛋白氮浓度平均值较A3组增加了8.97%,瘤胃液和血浆尿素氮浓度平均值稍低于A3组,但差异均不显著(P0.05),而瘤胃液NH3-N浓度平均值则显著低于A3组(P0.05)。2)粗饲料中燕麦干草的加入并未显著改变绵羊瘤胃液总挥发性脂肪酸浓度和丙酸摩尔比平均值(P0.05),升高了瘤胃液乙酸、丁酸摩尔比以及乙酸/丙酸平均值,且A3组与A1组差异显著(P0.05)。由此可知,在精料相同、精粗比为35∶65的条件下,用50%全贮玉米青贮和50%燕麦干草混合作为粗饲料可以改善绵羊的瘤胃内环境而适宜瘤胃微生物生长,提高瘤胃微生物活性及其对氨(NH3)的利用率,有助于微生物蛋白的合成,升高瘤胃乙酸的摩尔比及乙酸/丙酸。     

Effect of starch application into the proximal duodenum of ruminants on starch digestibility in the small and total intestine.

Four Slovakian Black-and-white bulls (LW 410 +/- 12 kg; Exp. 1) and four Slovakian Black-and-white non lactating dairy cows (LW 475 +/- 14 kg; Exp. 2) with permanent ruminal cannulas, duodenal T-cannulas and ileal re-entrant cannulas were used in a 4 x 4 Latin square design to determine the postruminal capacity of starch digestion. In Exp. 1 bulls received 5.4 kg DM from corn silage and 3.6 kg DM from alfalfa hay, in Exp. 2 cows consumed only 2.1 kg DM corn silage and 1.9 kg DM alfalfa hay. Additionally, either 750 or 1500 g (Exp. 1) or resp. 1000 or 2000 g (Exp. 2) gelatinized corn or wheat starch per animal and day were applied as pulse doses or as infusion into the proximal duodenum. In both experiments the duodenal and ileal nutrient flow, as well as the faecal excretion without starch application, were measured in a pre-period. After starting starch application ileal digesta and faeces were sampled over 120 h after 9 or 23 days of adaptation respectively. Cr2O3 was used as a flow marker. It was shown, that the capacity of starch utilisation in the small intestine was limited. The effect of different doses of bypass-starch was more pronounced than the effect of different starch sources. Starch digestibility decreased with increasing amounts of starch in the intestine (Exp. 1: corn starch: from 74.3 to 68.0%, P < 0.001; wheat starch: from 76.7 to 67.4%, P < 0.001; Exp. 2: corn starch: from 71.4 to 50.3%. P < 0.001; wheat starch: from 73.8 to 53.1%, P < 0.001). Corn starch was 0.6 to 2.4% units (P < 0.05) and 2.4 to 2.8% units (P < 0.001) less digested than wheat starch in Exp. 1 and Exp. 2, respectively.     

贵州省优质饲草加工技术及其效益分析

由于贵州省空气湿度大,导致该地区干草系列产品发展的成本较高,且无法适应市场规律,因此,更适合发展优质饲草青贮及发酵全混合日粮（FTMR）等厌氧保存产品。而在实际生产过程中,农户和养殖企业则更加关心这些饲草产品的生产成本。介绍了优质饲草的青贮和FTMR加工技术,并以肉牛为例,分析了贵州省较为常见的青贮玉米、燕麦、苜蓿干草青贮和FTMR的饲喂价值、生产成本和效益,以期能为贵州饲草加工和草食家畜养殖企业提供参考。