The protozoa population in the rumen of fattening bulls fed varying feed and the effect of artificial transfer of protozoa]

High protozoa concentrations were found in the ruminal fluid of fattening bulls weighing 400 kg which were raised for the first five months of age in a large-size calf-raising plant. The ruminal fluid of these bulls, however, contained no protozoa of the group Holotricha. If the animals were fed a mixture of concentrates and pelleted straw (pH 6, 12.5 mMole of volatile fatty acids per 100 ml) 1 ml of the ruminal fluid was found to contain 827,000 protozoa whereas if the animals received rations rich in concentrates (pH 5.8, 14 mMole of volatile fatty acids) 1 ml of ruminal fluid contained only 578,000. Through protozoa transfer carried out by infusing 41 of a mixture of ruminal fluid from other cows per animal it was possible to settle other species, viz. Isotricha, Dasytricha and Ophryoscolex; this, in turn, produced a concomitant decrease in the number of Entodinium and a noticeable decline in the total protozoa population. Further work will be necessary to find out whether it would be advisable to influence the protozoa population of growing cattle kept in large-size cow plants in similar ways as described above.     

The effect of pelleting cereal straw with NaOH-addition on rumen fermentation in cows]

Experiments with rumen-fistulated dairy cows were performed to study the effect of NaOH-addition to cereal pellets. Compared to straw-concentrate rations in which the straw pellets were free of NaOH, cereal straw pellets containing 2.4 kg NaOH per 100 kg straw caused the rumenal pH to go up from 6.21 to 6.47, the cellulotlytic activity to rise by some 20%, and the passage turnover rate of dry matter to increase from 0,039 to 0,056. The concentrations of volatile fatty acids and the fermentation patterns were not influenced by the NaOH-content of the pellets. It is concluded that NaOH-addition during straw pelleting has a favourable effect on digestion in the bovine rumen.     

The dynamics of the content of ammonia and volatile fatty acids in the rumen fluid during the use of dry feed rations in the cow

The development of the pH-value, the molar quota of volatile fatty acids and of the NH3 content in the change from silage rations to dried rations on the basis of pelleted feed and in dependence on the time after the beginning of feeding was tested in studies of the rumen fluid of four cows in order to explain the causes of the very low NH3 content of the rumen fluid in feeding experiments with rations based on pelleted straw-concentrate mixtures. An influence of the ration type and the time after the beginning of feeding on the molar quota of the individual volatile fatty acids and the NH3 content was ascertained. The ration type tested can cause an NH3 content in the rumen fluid below 1 mmol/l.     

The influence of different straw-based ration type on fermentation and production of volatile fatty acids in the rumen of lactating cows. 3. Rumenal fermentation processes and milk yield criteria after using a low-fiber straw pellet batch as basal ration component and a fully pelleted straw-based ration

Lactating Black-Pied (DSR) cows were used to study, over a period of 100 days, the influence of different basal ration types (I-treated wheat straw pellets, low-fibre; II- monodiet pellets containing 48% of wheat straw; III = conventional rations based on fresh forage and arable root crops) on the molar fermentation pattern and the daily rate of VFA production and some milk yield criteria. Ration types I and II results in almost equal fermentation patterns of the VFA; as against the conventional ration types (III) a significantly higher molar acetate propertion as well as a highly significantly decreased molar proportion of iso-acids were found. The daily rated of VFA production relativated to energy intake were as follows (in the order of the ration types mentioned): 4.9, 4.2 and 5.0, and 3.3, 2.5 and 3.3 moles per 1,000 anergetic feed equivalents (cattle) after 30 and 100 days of feeding, respectively. In both trials, only about 80% of the relative VFA production of the straw pellet-concentrate (I) and conventional (III) ration types were found when feeding fully pelleted diets (II). On account of the relatively wide variation of the experimental results no statistically secured findings were obtained as to the milk yield criteria, but ration type II produced some 200 and 300 kg milk less thant ration types I and III, respectively, during the 100-day experimental period.     

秸秆制粒对肉牛反刍、消化、瘤胃发酵及体增重的影响

本研究测定分析了秸秆制粒饲喂肉牛对其采食、反刍、养分表观消化率、瘤胃发酵和增重的影响,以丰富秸秆饲料化利用方式。试验选取30头18月龄左右、活重接近的西杂肉牛,随机分成3组(每组10头),分别饲喂粉碎玉米秸秆(对照组)、玉米秸秆颗粒饲料(试验Ⅰ组)及玉米秸秆精粗饲料颗粒(试验Ⅱ组)。结果表明,1)秸秆制粒饲喂肉牛,其采食、反刍、咀嚼时间均有所缩短,且每食团咀嚼时间显著少于对照组(P=0.004),而试验Ⅱ组采食时长显著低于对照组(P=0.032)。2)除试验Ⅰ组中性洗涤纤维的表观消化率显著低于对照组外(P<0.05),3组肉牛其他养分的表观消化率均无显著差异。3)秸秆粉碎制料后饲喂肉牛影响瘤胃发酵,与对照组比较,试验Ⅰ组瘤胃pH值及丁酸含量显著下降(P<0.05),而乙酸含量和乙酸/丙酸显著升高(P<0.05);试验Ⅱ组瘤胃液丁酸含量显著下降(P<0.05),乙酸/丙酸及NH₃-N含量显著升高(P<0.05)。4)秸秆粉碎制粒饲喂肉牛能显著增加日增重和饲料转化率(P<0.05),试验Ⅰ组及试验Ⅱ组日增重较对照组分别高出0.36和0.38 kg,饲料转化率(料重比)分别提高27.86%和29.09%。     

The use of partly-hydrolyzed and untreated straw meal in the feeding of breeding sows. 5. Concentration, production and absorption of volatile fatty acids in the large intestine

In 2 experiments with a total of 28 breeding sows of the country species studies were made of the fermentation, production and absorption of volatile fatty acids (VFA) in the large intestine after feeding variously treated straw materials in concentrate--straw meal mixtures. Experiment 1 ascertained that supplements of untreated (I), HCl treated (II) and partly hydrolysed straw meal (III, treatment with subsequent steaming) caused a decrease of the VFA concentration as well as considerable molar changes of the VFA in the caecal and colonal digesta in comparison of the sole feeding with concentrate (IV). The straw fibre integration increased the molar acetate quota at the expense decreased propionate and butyrate fermentation. Considering the straw meal variants this effects was least distinct after the feeding of partly hydrolysed straw meal (III). In experiment 2, which comprised the simultaneous ascertainment of VFA production in the feeding variants I and III and which was based on a representative number of animals per test group (n = 10), there were significant differences between the production quotas (I = 992; III = 1,300 mmol/animal.d) and in the absorption quotas of VFA (I = 63; II = 78%). The digestible energy from the VFA in the large intestine amounted to 711 kJ/d (I) and 1,183 kJ/d (III). The derived higher net energy gain from the hydrolysed straw product (III) was calculated at 590 kJ (40EFUpig/kg DM) and discussed together with results of feed value increase from the digestibility experiments.     

Effects of feeding frequency on intake, ruminal fermentation, and feeding behavior in heifers fed high-concentrate diets

Four ruminally fistulated Holstein heifers (BW = 385 +/- 6.2 kg) were used in a 4 x 4 Latin square experiment to determine the effect of feeding frequency on intake, water consumption, ruminal fermentation, and feeding and animal behavior. The treatments consisted of different feeding frequencies: a) once daily (T1); b) twice daily (T2); c) 3 times daily (T3); and d) 4 times daily (T4). Heifers were offered ad libitum access to concentrate and barley straw. Feeding frequency did not affect DMI (P >0.10), but water consumption tended to increase linearly as feeding frequency increased (P = 0.08). Average ruminal pH was not affected (P >0.10) by feeding frequency, but at 12 h after feeding ruminal pH was greater for T2 than for the other treatments. Total VFA concentration and VFA proportions were not affected (P >0.10) by feeding frequency, except valerate proportion, which increased linearly (P = 0.05) as feeding frequency increased. The concentration of ammonia-N was affected (P <0.05) cubically as feeding frequency increased (greatest for T3 = 9.3 mg of N/100 mL; lowest for T2 = 7.2 mg of N/100 mL). Feeding frequency had no effect on daily percentages of behavioral activities (P >0.05), except for observational behavior, for which there was a linear decrease as feeding frequency increased (P = 0.02). Heifers spent the same time on chewing activities, independent of feeding frequency. However, meal criteria tended to be affected (P = 0.07) by feeding frequency, with T2 (39.4 min) showing the longest intermeal interval. Total daily meal time, meal frequency, and meal size were not affected by feeding frequency (P >0.10), whereas meal length and eating rate showed cubic tendencies (P = 0.10 and P = 0.06, respectively) as feeding frequency increased. These results suggest that in the present experimental conditions, with heifers fed high-concentrate diets and with noncompetitive feeding, a smaller range of ruminal pH values was observed when feed was offered twice daily. Although heifers spent the same time on chewing activities, more stable ruminal conditions were probably achieved by feeding twice daily due to the rumination pattern, which was more constant during daytime in T2 than in T1. Moreover, when daytime and nighttime ruminating activity were analyzed separately, this activity was different in T1 (17.3 vs. 30.8%, respectively; P <0.05) but not in T2 (21.5 vs. 28.0%, respectively; P >0.05).     

Effects of ruminal dosing of mechanical stimulating brush on digestibility and rumen fermentation status in Holstein steers fed low rice straw at different lengths

The objectives of the present study were to determine the effect of ruminal dosing of mechanical stimulating brush (Rumen faibu; RF) on digestibility and on rumen fermentation status in Holstein steers fed high concentrate and low rice straw. Eight steers (461 kg in average bodyweight) were used. Four steers were orally dosed three RF per head (RF‐dosing) and the other four were not dosed (non‐RF). All steers were fed enough concentrate and rice straw to gain 1.4 kg/day in bodyweight. Rice straw was cut 2 cm and 30 cm. The organic cell wall content of feeding diets was 17% in dry matter basis. Digestibility and nutritive value were not affected by RF dosing and length of rice straw. Ruminal pH was significantly lower in RF‐dosing group than in non‐RF group after feeding, and tended to be higher in long rice straw than in short rice straw throughout the day. There were no clear difference on total volatile fatty acid concentration and molar proportion of volatile fatty acid by RF dosing and length of rice straw throughout examined period. These present results suggest that digestibility and rumen fermentation status are not affected by RF dosing when organic cell wall content of feeding diets is approximately 17% in dry matter with rice straw over 2 cm.     

Effect of nitrogen source in high-concentrate, low-protein beef cattle diets on microbial fermentation studied in vivo and in vitro

In Exp. 1, four Holstein heifers (112+/-5.5 kg BW) fitted with ruminal cannulas were used in a 4 x 4 Latin square to evaluate the effects of N source on ruminal fermentation and urinary excretion of purine derivatives. A 2 x 2 factorial arrangement of treatments was used; the factors were the type of protein source (soybean meal, SBM, vs a 50:50 mixture of fish meal and corn gluten meal, FMCGM) and the partial substitution of protein source by urea (with vs without). Heifers were allowed to consume concentrate and barley straw on an ad libitum basis. Barley straw:concentrate ratio (12:88) and average ruminal pH (6.25) were not affected (P > 0.05) by treatment. Ruminal NH3 N concentration and urinary excretion of purine derivatives were not affected (P > 0.05) by supplemental N source. In situ CP degradability of supplemented SBM was very low (50%). In Exp. 2, eight dual-flow continuous-culture fermenters were used to study diet effects on microbial fermentation and nutrient flow, using forage:concentrate ratio, solid and liquid passage rates, and pH fluctuation to simulate in vivo conditions. The treatment containing SBM without urea reached the greatest total VFA concentration (P < 0.01), molar percentage of acetate (P < 0.05), and NH3 N concentration (P < 0.05), followed by treatments with partial substitution of protein source by urea, and finally by the treatment containing FMCGM. True OM digestion tended to increase (P = 0.13) in treatments containing SBM. These results suggest that amino N from SBM and NH3 N concentration stimulated nutrient digestion. Microbial protein synthesis was lowest in treatments with FMCGM and without urea, indicating that rapidly available N limited microbial growth. The low CP degradability of SBM observed may have contributed to the limitation in N supply for microbial growth. Efficiency of microbial protein synthesis increased in treatments containing urea (P < 0.05). Protein source affected total (P < 0.05) and essential AA (P < 0.10) flows, which were greater in treatments containing FMCGM. Partial replacement of protein supplements by urea did not affect total and essential AA flows. Because mean dietary protein contribution to total N effluent was 46%, the AA profile of supplemental protein sources had a great impact on total AA flow and its profile.     

Effect of supplemental yeast culture and sodium bicarbonate on ruminal fermentation and blood variables in rams

A trial was conducted to evaluate the effect of sodium bicarbonate (BC) and Saccharomyces cerevisiae, live yeast culture (yea sacc(1026), YS) on ruminal fermentation and blood variables. Four Kivircik rams with ruminal cannula were used in a Latin square design, during 27-day periods (20 days for adaptation and 7 days for collection). They received 0 (control group), 5 g/day (i.e. 25 x 10(9) CFU) of YS or 10 g/day of sodium BC or 10 g/day of BC and 5 g/day of YS (BC + YS) (treatment groups). The cultures and sodium BC were added to the ration in a grain mix. The ration consisted of 70% grain mix and 30% lucerne hay. Rumen contents were collected before and 3 h and 6 h after morning feeding on days 1 and 7 in each collection period and were analyzed. Blood samples were also collected on the same days. Ruminal pH at 3 h (p < or = 0.1) and 6 h (p < or = 0.05) after feeding were higher when rams were fed BC and BC + YS than when they were fed CG and YS. Addition of YS to the diet did not modify the proportions of the different protozoa types; only Diplodinium at 0 h tended to be lower (p < 0.1) when rams were fed YS, BC and BC + YS than when they were fed CG. Plasma sodium value decreased by YS and BC + YS. Other biochemical and haematological variables were not affected by treatments. Also total volatile fatty acid, NH3-N concentrations and protozoa counts in the ruminal fluid were not affected by treatments.     

Interrelationships in the digestion of sheep given barley grain diets containing either fish meal, soya-bean meal or urea

Three sheep, each fitted with a ruminal cannula and duodenal re-entrant cannulae were given three isonitrogenous, isoenergetic diets in a Latin Square design. Each diet contained approximately 60% DM as barley grain and 40% of total N as either white fish meal, soya-bean meal or urea. These diets were fed continuously and supplied about 28 g N/day. Diets containing such large amounts of barley grain usually produce wide variations in the rumen volatile fatty acid (VFA) proportions and these have been correlated with various other digestive characteristics. Several ruminal and duodenal components were measured in this study and interrelationships between them sought. The molar proportions of VFA varied widely from 45-67% for acetate, 13-48% for propionate and 7-23% for butyrate. Rumen pH was positively correlated with acetate (P less than 0.01), but negatively so with propionate (P less than 0.01) and butyrate (P less than 0.1). The numbers of rumen ciliate protozoa also varied widely and were related to rumen pH (P less than 0.05) and VFA proportions; positively to acetate (P less than 0.001) and butyrate (P less than 0.01) but negatively to propionate (P less than 0.001). Duodenal N was always less than fed N. The mean composition of this duodenal N was 10.1% ammonia-N, 6.7% RNA-N, 79.0% amino acid-N and 7.3% was unaccounted for. Efficiencies of synthesis of microbial and bacterial crude protein (derived from 35S and 2,6-diaminopimelic acid data) ranged from 10.5 to 42.2 g microbial N per kg apparently digested organic matter (ADOM) and 5.0 to 27.9 g bacterial N per kg ADOM. Division of VFA patterns into either propionate or butyrate type fermentations suggested several further interrelationships. No relationship was established between these fermentation patterns and the extent or efficiency of microbial crude protein synthesis. Possible interrelationships between different digestive characteristics are discussed and a plea made for both more extensive and intensive experimentation before such designation of cause and effect can be assigned.     

Eating and ruminating behavior of sheep. 2. Experiments in pregnant and lactating ewes fed with a straw-concentrate mixture

Fertility oriented ewes in the late stage of gestation and during the lactation period received 19 feeding regimes on the basis of straw-concentrate mixtures, which essentially differed in the feedstuff structure. The ewes fed ad libitum on average used between 5 and 6 hours per day feed intake in the 86 measuring periods. The average daily ruminating time ranged from 398 to 502 minutes. An increasing straw content resulted in significantly longer ruminating periods and a higher number of masticatory movements, additional quotas of long straw had non effect. But even the most unfavourable feeding variants (straw-concentrate mixtures with 40% straw meal treated with NaOH) elicited 21 100 ruminating masticatory movements in 5 hours of ruminating. There were no significant differences between the absolute consumption and ruminating activities in the late stage of gestation and the lactation period; with reference to feed and crude fibre intake the ruminating expenditure in the late stage of gestation was always significantly higher. Rations with a low structural effect resulted in a more unbalanced distribution of consumption and ruminating activities in the course of the day than well structured rations.     

体外产气法评价油菜秆与玉米、豆粕的组合效应

本研究旨在探讨不同比例的油菜秆与玉米、豆粕组合对体外瘤胃发酵及其组合效应的影响。采用体外发酵法研究油菜秆与玉米(0%, 15%, 30%)、豆粕(0%, 15%, 30%)组合的体外发酵参数及其组合效应值的变化,探索优化组合效果。结果表明,随着玉米比例的增加,乙酸、丙酸、丁酸和挥发性脂肪酸生成量相应增加,乙丙比下降。当油菜秆∶玉米∶豆粕为40∶30∶30时,培养液pH,氨态氮(NH₃-N)浓度和乙丙比均极显著下降(P<0.01);48 h产气量、潜在产气量、产气速率、乙酸、丙酸、总挥发性脂肪酸(VFA)浓度和有机物消化率(OMD)均极显著提高(P<0.01)。以48 h产气量、NH₃-N、挥发性脂肪酸浓度和OMD的组合效应值以及综合组合效应值(AEs)为衡量指标,油菜秆∶玉米∶豆粕为55∶30∶15组合的正组合效应最大(P<0.01)。综上所述,在本试验条件下,油菜秆∶玉米∶豆粕为55∶30∶15组合的能氮比例较为合理,瘤胃发酵效率最高,为最优组合,可提高油菜杆的利用效率。     

Ruminal fermentation pattern, bacterial population and ruminal degradation of feed ingredients as influenced by ruminal ammonia concentration

The effects of ruminal ammonia concentration on bacterial numbers, fermentation pattern and degradation of feed ingredients in the rumen were examined with three nonlactating Holstein cows fitted with ruminal cannulas. Cows were fed twice daily a complete mixed diet (90% whole plant oat silage and 10% concentrate mixture) containing 11.1% CP on a DM basis. Ammonium bicarbonate (NH4HCO3) was infused continuously into the rumen at levels of 0, 95, 190 or 280 g/d. Infusion of NH4HCO3 linearly increased (P less than .05) the concentrations of ruminal ammonia and blood urea N. Total VFA concentrations and mixed bacterial numbers also were increased (P less than .05) by NH4HCO3 infusion. Infusions of NH4HCO3 increased (P less than .05) butyrate and decreased (P less than .05) isobutyrate and isovalerate proportions. Infusion of NH4HCO3 increased (P less than .05) rate of degradation of soybean meal DM but did not (P greater than .05) influence degradation characteristics of fish meal and barley grain. In conclusion, supplementation of N by continuous infusion of NH4HCO3 appeared to stimulate bacterial growth and fermentation but it did not influence extent of ruminal degradation of selected feed ingredients.     

Ruminal protein metabolism and intestinal amino acid utilization as affected by dietary protein and carbohydrate sources in sheep.

Eight wether lambs fitted with ruminal, duodenal, and ileal cannulas were used in a replicated 4 x 4 Latin square design to study the effects of carbohydrate and protein sources on ruminal protein metabolism and carbohydrate fermentation and intestinal amino acid (AA) absorption. Treatments were arranged as a 2 x 2 factorial. Carbohydrate sources were corn and barley; protein sources were soybean meal (SBM) and fish meal (FM). Diets contained 15.5% CP, of which 40% was supplied by SBM or FM. Corn or barley provided 39% of dietary DM that contained equal amounts of grass hay and wheat straw. Fish meal diets produced a lower (P less than .05) ruminal NH3 concentration and resulted in less CP degradation and bacterial protein flow to the duodenum than did SBM diets. Replacing SBM with FM increased (P less than .05) ruminal digestion of all fiber fractions. In addition, cellulose and hemicellulose digestibilities in the rumen tended to increase (P greater than .05) when barley replaced corn in the FM diets. Carbohydrate x protein interactions (P less than .05) were observed for OM digestion in the rumen and AA absorption in the small intestine (percentage of AA entering); these interactions were highest for the barley-FM diet. These results suggest that feeding FM with barley, which is high in both degradable carbohydrate and protein, might benefit ruminants more than feeding FM with corn, which is high in degradable carbohydrate but relatively low in degradable protein.     

油菜秆颗粒料对湖羊生产性能、瘤胃发酵参数及血液生化指标的影响

本试验探索了油菜秆颗粒料对湖羊生产性能、瘤胃发酵参数及血液生化指标的影响。试验选取30只6月龄体重为(32.33±1.65) kg的健康公湖羊,按体重配对设计分为2组,对照组和试验组分别饲喂花生藤颗粒饲料和油菜秆颗粒饲料,试验期52 d。测定了日增重、饲料转化效率、瘤胃发酵参数、饲料表观消化率及血液生化指标。结果显示,与对照组相比,试验组湖羊的干物质采食量(1.37 kg对1.47 kg)显著低于对照组(P<0.05),日增重基本一致(147 g对143 g);试验组瘤胃液中总VFA(102.27 mmol/L对90.44 mmol/L)(P<0.05)、丙酸(17.08 mmol/L对13.79 mmol/L)(P<0.01)、丁酸(11.97 mmol/L对10.31 mmol/L)(P<0.01)、氨态氮浓度(15.90 mg/dL对11.33 mg/dL)(P<0.01)的含量显著升高,乙丙比(P<0.01)(3.96对4.33)显著降低;中性洗涤纤维的表观消化率有升高的趋势(54.75%对51.50%)(P=0.09);血液中葡萄糖浓度显著升高(3.77 mmol/L对2.97 mmol/L)(P<0.05),尿素氮浓度(11.01 mmol/L对12.80 mmol/L)(P<0.01)、游离脂肪酸(133.07 umol/L对144.50 umol/L)(P<0.05)、谷丙转氨酶(14.85 U/L对19.23 U/L)(P<0.05)和高密度脂蛋白(0.92 mmol/L对1.05 mmol/L)(P<0.05)浓度显著降低;每kg增重饲料成本试验组比对照组降低了5.87元。结果表明,以油菜秆为主的颗粒料饲喂生长湖羊,对其健康无不良影响,可降低饲料成本,增加养殖效益,是丰富南方地区湖羊粗饲料来源、减少区域油菜秆污染的可行途径。     

Feed intake of ewes in the perinatal period

8 individual feeding experiments served the ascertainment of the consumption performance of ewes in the perinatal phase. In 6 experiments with a total of 176 fertility oriented ewes the daily intake of pelleted straw-concentrate mixtures between the 4th week ante partum and the 6th week post partum was determined. On average the ewes consumed 1701 g dry matter in the last phase of gestation and 2271 g DM during lactation per animal and day. Intense grinding and NaOH-treatment increased feed intake; high straw content, limited duration of feeding and NH3-treatment decreased it. A higher number of lambs had, in the last phase of gestation, a decreasing and during lactation an increasing effect on consumption. Maize silage in the last phase of gestation resulted in very low feed intake. In contra to this, rations of alfalfa hay and maize silage were consumed well during lactation. There were no significant differences due to species or age with regard to consumption performance.     

Alternate day supplementation of corn stalk diets with soybean meal or corn gluten meal fed to ruminants.

Four experiments were conducted to determine the effect of adding corn gluten mean (CGM) or soybean meal (SBM) at 24- or 48-h intervals to diets based on corn stalks. In each experiment corn stalks was the primary diet ingredient fed to wethers or steers. Monensin was also fed to determine whether its effects on ruminal fermentation would improve the efficiency of N utilization under these conditions. Evaluation criteria included ruminal fermentation characteristics, DM intake and utilization, N balance in sheep, and steer feedlot performance. Ruminal ammonia nitrogen (NH3 N) concentrations measured over time were higher (P < .05) when diets contained SBM. Diet did not influence (P > .10) total VFA concentrations in ruminal fluid. Differences in diurnal shifts in ruminal NH3 N and total VFA due to protein source resulted in diet x hour interactions (P < .05). Dry matter intake response to protein source and frequency of supplement feeding was variable. Dry matter digestibility and nitrogen digestibility were not affected (P > .10) by protein source or feeding interval. The 48-h interval feeding of CGM was favorable compared with 24-h interval feeding (P < .05). The opposite response occurred with SBM, resulting in a diet x feeding interval interaction (P < .05). Nitrogen retention was greater (P < .05) when CGM was fed and with alternate day feeding. Diets that contained CGM supported higher (P < .05) ADG and gain/feed than diets that contained SBM when fed to steer calves. Alternate day feeding of supplements that contained monensin was detrimental to steer performance under the conditions of these experiments. Corn gluten meal is an effective substitute for SBM when alternate day protein supplementation is practiced.     

Occurrence of 2-aminoethylphosphonic acid in feeds, ruminal bacteria and duodenal digesta from defaunated sheep

A quantitative method of analysis for 2-aminoethylphosphonic acid (AEP) was developed using reverse-phase HPLC. The detection limit for AEP was 15 nM, and the detector response (peak area) was linear from AEP levels up to 100 microM (R = .99). Mean recovery of AEP added to strained ruminal fluid from faunated sheep was 98.2%. When AEP was added to a fermentation mixture at a concentration of 22.6 micrograms/ml, 78% disappeared during a 24-h incubation. 2-Aminoethylphosphonic acid was readily detected in preparations of mixed ruminal ciliate protozoa as well as in mixed and pure strains of ruminal bacteria, feedstuffs, and ruminal fluid and duodenal digesta from defaunated sheep. The occurrence of AEP in feed and bacterial hydrolysates was confirmed by organic phosphorus analyses. The concentration of AEP in mixed ruminal protozoa was three times greater than its concentration in mixed ruminal bacteria (4,304 vs 1,383 micrograms/g DM, respectively). The AEP values for pure ruminal bacterial cultures ranged from 733 micrograms/g DM in Bacteroides succinogenes B21a to 1,166 micrograms/g DM in Butyrivibrio fibrisolvens H17c. Ruminal fluid and duodenal digesta from defaunated sheep contained AEP concentrations of 30 micrograms/ml and 90 micrograms/g DM, respectively. The concentration of AEP in feedstuffs ranged from 25 micrograms/g DM in wheat straw to 263 micrograms/g DM in oats. Because AEP occurrence is not limited to ruminal ciliate protozoa, it is of little value as a marker for protozoal presence in or passage out of the rumen.     

绵羊日粮中不同碳水化合物比例对瘤胃内环境参数的影响

本研究以18只安装有瘤胃瘘管的内蒙古半细毛羯羊作为试验动物 ,研究了绵羊日粮中6个不同结构性碳水化合物(SC)与非结构性碳水化合物(NSC)比例(3.52、3.32、2.86、2.64、2.40和1.88)对绵羊瘤胃内环境参数随时间的动态变化的影响。结果表明 ,绵羊日粮中一定范围内的SC :NSC比例对瘤胃内 pH和NH3-N浓度的影响不显著 ,但会改变瘤胃内VFA的摩尔比例。若适度提高丙酸浓度 ,调控瘤胃发酵模式 ,可达到提高纤维物质利用率的目的。