Changes in amino acid levels in bacteria adhering to rumen epithelium in sheep after oral administration of very low doses of mercury

The effect of low concentrations of mercury taken in the diet (4 mg per a head and day) on the amino acid composition in the proteins of rumen bacteria adhering to the dorsal and ventral parts of the rumen was studied in six sheep. Though the mercury did not influence the amino acid concentration in hydrolyzates of epimural bacteria, low-mercury doses caused significant changes of some amino acids, as compared with the control group of animals. The levels of alanine, histidine, threonine, serine and glycine were significantly decreased and at the same time the levels of proline, valine, isoleucine, tyrosine, lysine and phenylalanine were significantly increased. It was stated in our experiment that the levels of histidine, alanine and threonine in hydrolyzates of epimural bacteria of the rumen were significantly decreased both in the sheep given the balanced feed ration with additions of mercury and nitrogen (according to the standard) and in the sheep given a low-nitrogen diet. Similarly, the levels of proline, tyrosine and phenylalanine in the hydrolizates of epimural bacteria in rumen were significantly increased both with the low-nitrogen diet and in the normal -nitrogen diet with mercury supplement. The results suggest that unexplained disorders frequently occurring in the microbial synthesis in the rumen might be caused by long-continued administration of feed contaminated with extremely low concentrations of heavy metals. The problem deserves detailed investigation in future studies, oriented to explaining the biosynthesis disorders in rumen, reducing the production ability of ruminants.     

Elution of bacteria adhering to the epithelium in the rumen in sheep and their detection using electron microscopy

A method of preparing the pure concentrate of epithelium-adherent bacteria in sheep rumen was worked out and it was tested in 24 samples of the rumen wall, obtained from 12 slaughtered sheep. The purity of the bacterial eluate was checked by transmission electron microscopy and negative staining, followed by electron-microscopic evaluation. Besides bacterial cells no residues of feed, epithelium and other undesirable impurities were found out in the eluate. The percent yield of this method was determined by scanning electron microscopy and it made 93.3%. An isolated pure concentrate of the mixture of bacterial cultures, previously adhered to the rumen epithelium, was prepared which can be used for morphological and biochemical studies of this interesting group of rumen bacteria.     

Motility of the rumen after feeding sheep pelleted rations]

In an experiment with wethers the effect of the feeding with pelleted feed rations and the partial replacement of coarse fodder by non-treated beech sawdust on the motorial activity of the rumen was observed. The rumen motility was measured through a rumen fistula by means of the balloon method with the help of a capacitator primary unit, an electric manometer and a recording instrument. Over a period of 24 weeks the animals consumed 1.3 kg dry matter per day. It consisted of 41.8% meadow hay, 25.3% barley, 15.4% sawdust, 15.0% molasses, 1.3% urea, 0.76% mixed minerals and 0.48% hexametaphosphate in the form of pellets (test group) or the traditional classical form (control group). The feeding of pellets diminished the frequency (P less than 0.001) and the intensity of rumen contractions before and 1, 3 and 5 hours after feeding. Maximal frequency values were registered one hour after the food intake. During this time the number of secondary contractions of the rumen increased; differences of the frequency were, however, not registered, which means that the different physical form of the diet had no influence on the motorial activity of the rumen and that the food intake as such is the decisive factor. The diminished rumen motility in further hours after feeding was effected by treating the feed (grinding and pelleting).     

Physiological effects of feeding high levels of magnesium to sheep

The effects of feeding high levels of Mg to sheep on animal health, nutrient digestibility, metabolism of macro-minerals, blood and tissue mineral concentrations and hematological and histological tissue changes were evaluated. Six lambs were allotted to each of four diets supplemented with MgO to attain .2, .6, 1.2 or 2.4% Mg. Total fecal and urinary collections were made for the initial 20 d and last 10 d of a 50 d study. Diarrhea was noted in lambs fed the two highest Mg levels. Apparent digestibility of DM, ADF and CP decreased linearly (P less than .01) with increasing Mg levels. Dietary Mg levels did not affect (P greater than .05) rectal temperature, respiration rate or pulse rate. Apparent absorption and retention of Mg (g/d) were lowest in lambs fed 2.4% Mg until 15 d on trial, after which values increased linearly (P less than .01) with dietary Mg. Phosphorus absorption and retention decreased linearly (P less than .01) with increasing Mg levels. Increasing dietary Mg resulted in a linear increase (P less than .01) in serum Mg and variable increases (P less than .05) in erythrocyte Mg. Serum Ca was decreased linearly (P less than .05) and quadratically (P less than .05) by added Mg during the d 1 to 30 and 40 to 50 periods, respectively. Serum inorganic P was elevated consistently in lambs fed 2.4% Mg. A linear response to increasing dietary Mg (P less than .05) occurred in the Mg content of liver, kidney, rib bone and femur bone. Dietary Mg did not alter (P greater than .05) other criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

配制氨基酸平衡日粮降低猪氮排泄的研究进展

氮评定方法的不断改进,有利于更精确地配制氨基酸平衡日粮,减少猪粪便中氮的排泄量.本文从减少猪粪便中氮排泄量的角度综述了配制氨基酸平衡日粮在养猪生产中的应用.     

In vitro transport of amino acids across the rumen mucosa in sheep]

Transfer of six amino acids through rumen epithelium of sheep has been studied on mucous and serous sides. Amino acids were classified into two groups: 1. lysine-arginine-glutamic acid, 2. glycine-alanine-leucine. The transfer of amino acids in triads was measured after 60 min. incubation. To determine amino acids transfer through rumen epithelium, three concentrations of amino acids were used: 1500: 150 and 15 mumol per 50 ml. In the first group of amino acids, the highest transfer of arginine was found in comparison with lysine and glutamic acid in all concentrations. The lowest transfer was found in glutamic acid. It follows from this that initial concentration of amino acids in the first group had no effect on amino acids transfer as far as the transfer of amino acids was as follows in all concentrations: arginine greater than lysine greater than glutamic acid. On the other hand, the composition of amino acids and initial concentration of amino acids in the second group exhibited the marked dependence on the transport of amino acids. The transfer of amino acids at the concentration of 1500 mumol per 50 ml was as follows: the passage of amino acids was the highest while this was lowest in alanine and leucine, at the concentration 150 mumol per 50 ml the highest transfer was found in alanine, it was lower in glycine and lowest in leucine and at the concentration 15 mumol per 50 ml the transfer of glycine was highest, lower in leucine and lowest in alanine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Determination of 2-6-diaminopimelic acid in samples of bacteria isolated from the rumen of sheep using an automatic amino acid analyzer

The method of the use of the HD 1200-E automatic amino acid analyzer for the separation of amino acids was modified for the determination of 2-6-diaminopimelic acid (DAPA) as a bacterial marker, besides the other amino acids in the acid hydrolyzates of samples of bacteria isolated from the rumen of sheep. The reproducibility of the determination of DAPA in a standard amino acid mixture found in the tests corresponded with the reproducibility of the determination of the other amino acids as indicated by the manufacturer of the apparatus. The lower limit of DAPA determination sensitivity is between 2 and 5 nmol. In samples of bacteria isolated from rumen wall, from feed particles of rumen contents and from rumen fluid, different contents of nitrogen and DAPA were obtained; this is ascribed to the different proportions of bacterial species in the bacterial populations having different functions.     

Development of rumen fermentation in calves during milk feeding]

The concentration of total volatile fatty acids (VFA) in the rumen fluid were increasing with the age of the animals (Fig. 1). A significant increase in the concentrations of total VFA (P less than 0.01) from 70.93 to 90.71 mmol/l was observed in the age period of 5-7 weeks and a highly significant increase (P less than 0.001) in the age period of 9-11 age. At the average age of seven weeks the lower boundary of the reference value range (80-120 mmol) of the total VFA concentrations in the rumen fluid as mentioned for adult animals was exceeded in the experimental calves. As to this parameter in individual calves, the level of the total VFA concentrations in the rumen fluid of adult animals was not reached in 50% of calves at the age of three weeks, in 80% of calves at the age of five weeks, in 20% of calves at the age of seven weeks and in 10% calves at the age of nine weeks. At the age of 11 weeks the concentrations of total VFA reached the level of adult animals in all experimental animals (Fig. 2). The molar proportion of acetate (Fig 3) decreased from 74.04 mol% at the age of three weeks to 67.54 mol% at the age of 11 weeks, and the propionate proportion increased from 16.73 to 19.53 mol% within the same interval.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in the composition of milk and rumen contents in cows exposed to a high ambient temperature with controlled feeding

Summary Two pairs of Jersey cows were exposed to either 15 or 30°C air temperature; intake of dried grass was controlled, to be equal ai both temperatures. Exposure to 30°C caused increases in rectal temperature and in respiratory rates, and decreases in food intakes in both cows. Milk yield decreased by similar amounts at both temperatures, in association with the decreases in food intakes. The fat and protein content of milk decreased significantly at 30°C; the proportion of shorter chain fatty acids (C₆-C₁₄) in the milk fat also decreased at 30° C. The proportion of acetic acid in the rumen contents decreased significantly at 30°C, in association with a small decrease in pH. The results indicate that changes in the metabolism of cows occurred at 30°C, independently of changes in food intake.

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Resumen Dos pares de vacas Jersey fueron expuestas a una temperatura ambiente de 15° y 30°C. respectivamente; la ingestión de hierba seca se controló para que fuera igual en ambas temperaturas. La exposición a 30°C. aumentó la temperature rectal y la rata respiratoria condisminución de la ingestión de alimento en ambas vacas. La secreción láctea disminuyó en cantidades iguales en ambas temperaturas en asocio con una disminución similar en la ingestión de alimento. El contenido de grasa y proteína de la leche disminuyó significativamente a 30°C; la proporción de cadenas cortas de ácidos grasos (C₆-C₁₄) en la grasa de la leche también disminuyó a 30°C. La proporción de ácido acético en el contenido del rumen disminuyó significativamente a 30°C. en asocio con una peque?a disminución del PH. Los resultados indican que los cambios en el metabolismo de las vacas ocurrieron a 30°C. independientemente de los cambios en la ingestión de alimentos.

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Résumé Deux paires de vaches jersiaises ont été exposées à une température de 15° ou 30°. La même ration d'herbe sèche a été donnée aux animaux soumis aux deux températures. L'exposition à 30° a provoqué une augmentation de la température rectale et des taux respiratoires et une diminution de l'absorption alimentaire chez les deux vaches. La production de lait diminue de la même fa?on aux deux températures, en même temps que diminue également la ration alimentaire. La teneur en graisse et en protéine du lait baisse de fa?on sensible à 30°. La proportion d'acides gras à chaine courte (C₆-C₁₄) dans les graisses du lait décro?t aussi à 30°. La proportion d'acide acétique dans le contenu du rumen diminue de fa?on significative à 30° en même temps que le pH accuse une diminution légère. Les résultats indiquent que des changements dans le métabolisme des vaches se produisent à 30° indépendamment des modifications de la ration alimentaire.

     

Changes in free amino acid serum levels in swine during parturition and in piglets during birth

During the course of parturition seven high pregnant sows, crossbreds of the Large White and Landrace breeds, and their 69 piglets being born, were studied for the changes of the total and separate free amino acids in the blood plasma in relation to the time of duration of the parturition, to the sequence of piglets being born in the litter, and to the birth weight of the piglets. The concentration of the total free amino acids in blood plasma is 2.44 +/- 0.182 mmol.l-1 just before parturition; after the birth of the last piglet it decreases insignificantly to 2.17 +/- 0.190 mmol.l-1. The concentration of the total free amino acids in the blood plasma of newborn piglets is always significantly higher than in their mothers (p less than 0.001) and is 4.24 +/- 0.109 mmol.l-1. The rank of each piglet in the sequence of births in litter has no influence on the level of plasma concentration of the total free amino acids amino acidaemia was 4.03 +/- 0.268 mmol.l-1 in the piglets born first and insignificantly changed to 3.99 +/- 0.445 mmol.l-1 of blood plasma in the last piglets born in the litter. The time factor of parturition is also statistically insignificant. However, the differences in the free "amino acids" concentration in the blood plasma between the piglets with the lowest weight and the piglets with a weight of up to 1200 and 1500 g are statistically significant (p less than 0.02). Alanine (0.43 +/- 0.052 mmol.l-1) and glycine (0.43 +/- 0.063 mmol.l-1) constitute the largest proportions of all the 17 amino acids studied in the blood plasma in the high pregnant sows before parturition. The tyrosine concentration in piglets at birth is remarkably high (1.44 +/- 0.035 mmol.l-1); it represent 34 per cent of the total amino acidaemia. Tyrosine, histidine and lysine concentration in the blood plasma is statistically highly significantly higher (p less than 0.001) in newborn piglets than in their mothers. The phenomenon of 6-times higher tyrosinaemia in piglets, compared with the sows is discussed in connection with the weight at birth and with the data on the function and concentration of thyroid hormones in piglets during the first days of their lives.     

Effect of dietary lactic acid on rumen lactate metabolism and blood acid-base status of lambs switched from low to high concentrate diets.

Two experiments were conducted with ruminally fistulated wether lambs to determine the effect of lactic acid addition to a hay diet on rumen lactate metabolism, blood acid-base status and subsequent adaptation to a high concentrate diet. In Exp. 1, lambs were fed mature brome hay (H), H plus 5% (w/w) D,L lactic acid (H5L) or H plus 10% lactic acid (H10L) (three lambs per treatment) for 14 days (phase I) then switched to a 90% concentrate diet for 2 days (phase II). In Exp. 2, lambs were fed alfalfa-brome hay (H) (six lambs), H plus 2.5% lactic acid (H2.5L) (six lambs) or H plus 5% lactic acid (H5L) (four lambs) during phase I, then switched to a 70% concentrate diet (3 days) followed by a 90% concentrate diet (10 days) (phase II). During both experiments rumen fluid samples were taken periodically for pH and lactate analyses and in vitro L- or D-lactate disappearance (IVLD) studies. Blood samples were taken to measure acid-base status, serum lactate, and serum calcium, magnesium and phosphorus. Dietary lactic acid enhanced IVLD during phase I of both experiments. L and D isomer IVLD rates were similar and followed zero-order kinetics. In Exp. 2, IVLD increased rapidly during phase II in response to increased concentrate level in the diet; the enhanced rates of H2.5L and H5L lambs were sustained for the first 3 days of phase II. Blood data from both experiments indicated a deleterious effect of dietary lactic acid on blood acid-base balance; however, this treatment effect was not manifested in any symptoms of acute acidosis. There was a decrease (P less than .05) in serum calcium during phase II of both experiments. In Experiment 1, serum calcium increased linearly (P less than .05) in response to dietary lactic acid level. In Exp. 1, rumen fluid total lactate and L-lactate were lower (P less than .05) for H5L vs H lambs during phase II. However, all lambs in Exp. 1 experienced acute acidosis; four of the nine lambs subsequently died. There was evidence of acidosis in Exp. 2, but there were no clear treatment effects during phase II on rumen fluid pH or lactate, or feed intake. All lambs adapted to the high concentrate diets as evidenced by rumen lactate levels and feed intakes. In both experiments, the proportion of L-lactate in rumen fluid decreased from almost 100 to about 50% of total lactate by the end of phase II.     

饲喂燕麦-箭筈豌豆捆裹青贮对绵羊瘤胃pH与氮代谢参数的影响

选用6只装有永久瘤胃瘘管的羯羊作为试验动物,采用3×3拉丁方设计,研究了A(100%燕麦—箭筈豌豆捆裹青贮料,简称青贮料),B(80%青贮料+20%玉米)和C(63%青贮料+37%玉米)3种饲粮处理对绵羊瘤胃内环境的影响。结果表明,瘤胃液pH值为A>B>C,但A的瘤胃液总氮含量平均值显著低于处理C(P<0.05);除食前1 h处理间NH3-N浓度差异接近显著(P=0.085)外,其他时段A,B和C差异显著或不显著(P<0.05或P>0.05);瘤胃液中尿素氮仅B和C食后8 h的测值和平均值显著(P<0.01或P<0.05)高于A;C的瘤胃液蛋白氮含量平均值显著高于A(P<0.05),但3种处理差异不显著。因此,3种饲粮试羊的瘤胃液pH值和微生物蛋白合成状况间没有显著差异。     

饲养水平对阿勒泰羊胃肠道发育、瘤胃发酵参数及瘤胃微生物区系的影响

为研究饲养水平对阿勒泰羊胃肠道发育、瘤胃发酵参数、消化酶活性及瘤胃微生物区系的影响,选取月龄相近(3～3.5月龄)、体重均一(19.16±0.54)kg、臀型一致、健康状况良好的阿勒泰母羔羊30只,随机分为3组,每组10只,自由采食60 d后,参照NRC(2007)饲养标准中维持能量(Em)需要,3个组分别按1.5Em...     

Influence of kanamycin on the rumen bacteria and ammonia production in supplemented sheep rumen liquor in vitro

Bacteriological studies were made with in vitro sheep ruminal fluids supplemented with synthetic fodder containing different amounts of kanamycin (0.125, 2.50, and 60 mg/ml), during anaerobic incubation at 38–39°C for 6 h.Changes in the bacterial population occurred in the presence of large amounts (60 mg/ml) of kanamycin, and the B₁-type strain of Eubacterium became predominant.The marked increase in the concentration of ammonia in the supplemented rumen liquor, obtained after anaerobic incubation with high dosages of this antibiotic, is discussed.     

日粮中添加不同水平红花油对绵羊瘤胃体外发酵动力学的影响

为探索红花油对瘤胃微生物发酵动力学的可能影响,试验以安装有永久性瘤胃瘘管的中国美利奴羊作为瘤胃微生物的供体动物,采用体外产气量法研究饲粮添加不同水平的红花油对绵羊瘤胃发酵动力学的影响。红花油的添加水平分别设0(对照组)、1%、2%和3%。结果表明:日粮添加2%和3%的红花油使产气速率和最大产气量明显低于对照组(P<0.05)。不同水平的红花油并未显著改变发酵液pH值、NH3-N浓度、CMCase及XYLase活性(P>0.05)。3%组的DM降解率略低于对照组(P<0.05),但与其他2个处理组差异不显著(P>0.05)。各处理组的NDF降解率较对照组也略有降低(P<0.05)。总挥发酸(TVFA)浓度、乙酸、丙酸摩尔百分比和乙丙酸比等指标各组间均差异不显著(P>0.05)。综上所述,饲粮中添加不超过3%水平的红花油对绵羊瘤胃发酵动力学没有负面影响。     

Free and peptide amino acid net flux across the rumen and the mesenteric- and portal-drained viscera of sheep

This experiment was conducted to determine the significance of the peptide amino acid (PAA) contribution to amino acid (AA) net flux in the portal vein and to evaluate the capacity for peptide absorption in the different segments of the gastrointestinal tract of ruminants. Four sheep (64+/-3 kg BW) were fitted with catheters and blood flow probes, allowing AA net flux measurements across the portal- (PDV) and mesenteric (MDV)-drained viscera and the rumen. Sheep were fed at maintenance a diet containing hay and extruded peas (70:30). Peptide absorption was investigated by a dose infusion of a mixture of peptides (casein hydrolysate, Pro-Phe, beta-Ala-His, Gly-Gly) into the rumen. Control and postinjection net fluxes of plasma free amino acids (FAA) and PAA were determined. The concentration of plasma PAA was determined by quantification of amino acids before and after acid hydrolysis of samples first submitted to chemical deproteinization and ultrafiltration (3-kDa cut-off filter). During the control period a significant net release (12 mmol/h) of PAA was observed across the PDV, which accounted for 35% of the sum of FAA and PAA net fluxes. This PDV flux of PAA mainly resulted from a MDV release of PAA (15 mmol/h). The net flux of total PAA across the ruminal wall was not significantly different from zero, but uptake of peptide Ile and release of peptide Gly were observed. The injection into the rumen of the peptide mixture increased the net release of peptide essential AA (EAA) across the MDV (P < .05) and the PDV (P < .10), and of peptide Pro and Phe across the non-MDV (P < .10). Peptide Ile uptake by the rumen tissues was decreased by the injection (P < .05). Significant increases in peptide Pro and Gly arterial concentrations were observed (P < .05). The 3-Ala-His and Gly-Gly arterial concentrations and net fluxes across the PDV were not affected by their injections into the rumen. This study showed that PAA may contribute significantly to AA flux across the PDV of sheep, and that part of this flux can probably be attributed to peptide absorption from the gut lumen. When high concentrations of peptides are generated in the rumen the possibility of peptide absorption before the jejunum has to be considered.     

Effect of feeding Acacia nilotica pods to sheep on nutrient digestibility,nitrogen balance,ruminal protozoa and rumen enzymes activity

This study was conducted to evaluate the effect of supplying two levels of Acacia nilotica (A. nilotica) pods to rations of sheep on nutrient digestibility, nitrogen balance and rumen liquor parameters (pH, total protozoa count, protein concentration and enzymes activity). Twelve mature rams (50 ± 1.25 kg B.W.) were distributed into three groups, each with four rams. Animals in group one were considered as a control which fed a basal diet, consisting of concentrate mixture and Egyptian clover. The second group and the third one received the same basal diet with supplying the concentrate mixture by 1.5% and 3.0% of A. nilotica pods meal respectively. The experiment lasted for 3 weeks. It was found that supplementation of A. nilotica pods to the concentrate mixture at a rate of 1.5% and 3.0% significantly improved the total feed intake compared to the control. The digestibility of dry matter and crude fibre was significantly reduced with A. nilotica supplements, whereas the digestibility of crude protein was significantly improved. All of nitrogen intake and N‐retained were significantly increased in rams fed on concentrates with 1.5% and 3.0% A.  nilotica pods when compared to the control. The pH of ruminal fluid was not affected by the dietary treatments. Nevertheless, the total rumen protozoa count was significantly decreased in A. nilotica pods supplemented groups. Also, the rumen protein concentration and the ruminal enzymes activity, especially α‐amylase, cellulase and protease, were lower in A. nilotica pods supplemented treatments. In conclusions, inclusion of low levels of A. nilotica pods (1.5% and 3.0%) in the concentrates can be used as a natural protein protectant in ruminants by forming tannin protein complexes in the rumen to maximize the amino acids available in the lower digestive tract. Also, these levels can increase the protein digestibility as well as the N‐retained in the body .