Cellulolytic-factor activity of certain short-chain fatty acids for rumen microorganisms in vitro

Mechanistic insights into inositol-mediated rumen function promotion and metabolic alteration using in vitro and in vivo models

Inositol is a bioactive factor that is widely found in nature; however, there are few studies on its use in ruminant nutrition. This study investigated the effects of different inositol doses and fermentation times on rumen fermentation and microbial diversity, as well as the levels of rumen and blood metabolites in sheep. Rumen fermentation parameters, microbial diversity, and metabolites after different inositol doses were determined in vitro. According to the in vitro results, six small-tailed Han sheep fitted with permanent rumen fistulas were used in a 3 × 3 Latin square feeding experiment where inositol was injected into the rumen twice a day and rumen fluid and blood samples were collected. The in vitro results showed that inositol could increase in vitro dry matter digestibility, in vitro crude protein digestibility, NH3-N, acetic acid, propionic acid, and rumen microbial diversity and affect rumen metabolic pathways (p < 0.05). The feeding experiment results showed that inositol increased the blood concentration of high-density lipoprotein and IgG, IgM, and IL-4 levels. The rumen microbial composition was significantly affected (p < 0.05). Differential metabolites in the rumen were mainly involved in ABC transporters, biotin metabolism, and phenylalanine metabolism, whereas those in the blood were mainly involved in arginine biosynthesis and glutathione and tyrosine metabolism. In conclusion, inositol improves rumen function, affects rumen microorganisms and rumen and blood metabolites and may reduce inflammation, improving animal health.

Effects of partially replacing dietary corn with molasses, condensed whey permeate, or treated condensed whey permeate on ruminal microbial fermentation

Corn is a feedstuff commonly fed to dairy cows as a source of energy. The objective of this study was to evaluate whether partially replacing dietary corn with molasses or condensed whey permeate, in lactating dairy cow diets in a dual-flow continuous culture system, can maintain nutrient digestibility by ruminal microorganisms. Furthermore, this study evaluated whether treating condensed whey permeate before feeding could aid the fermentation of the condensed whey permeate in the rumen. Eight fermentors were used in a 4 × 4 replicated Latin square with 4 periods of 10 d each. The control diet (CON) was formulated with corn grain, and the other diets were formulated by replacing corn grain with either sugarcane molasses (MOL), condensed whey permeate (CWP), or treated condensed whey permeate (TCWP). Diets were formulated by replacing 4% of the diet dry matter (DM) in the form of starch from corn with sugars from the byproducts. Sugars were defined as water-soluble carbohydrates (WSC) in the rations. The fermentors were fed 52 g of DM twice daily of diets containing 17% crude protein, 28% neutral detergent fiber, and 45% nonfiber carbohydrates. Liquid treatments were pipetted into each fermentor. After 7 d of adaptation, samples were collected for analyses of volatile fatty acids (VFA), lactate, and ammonia, and fermentors' pH were measured at time points after the morning feeding for 3 d. Pooled samples from effluent containers were collected for similar analyses, nutrient flow, and N metabolism. Data were statistically analyzed using Proc MIXED of SAS version 9.4 (SAS Institute Inc.); fixed effects included treatment and time, and random effects included fermentor, period, and square. The interaction of treatment and time was included for the kinetics samples. The TCWP and MOL treatments maintained greater fermentor pH compared with CWP. Total VFA concentration was increased in CWP compared with MOL. The acetate:propionate ratio was increased in TCWP compared with CON, due to tendencies of increased acetate molar proportion and decreased propionate molar proportion in TCWP. Lactate concentration was increased in MOL. Digestibility of WSC was increased in the diets that replaced corn with byproducts. The partial replacement of 4% of DM from corn starch with the sugars in byproducts had minimal effects on ruminal microbial fermentation and increased pH. Treated CWP had similar effects to molasses.

Volatile Fatty Acids in Ruminal Fluid Can Be Used to Predict Methane Yield of Dairy Cows

The dry matter intake (DMI) of forage-fed cattle can be used to predict their methane emissions. However, many cattle are fed concentrate-rich diets that decrease their methane yield. A range of equations predicting methane yield exist, but most use information that is generally unavailable when animals are fed in groups or grazing. The aim of this research was to develop equations based on proportions of ruminal volatile-fatty-acids to predict methane yield of dairy cows fed forage-dominant as well as concentrate-rich diets. Data were collated from seven experiments with a total of 24 treatments, from 215 cows. Forage in the diets ranged from 440 to 1000 g/kg. Methane was measured either by open-circuit respiration chambers or a sulfur hexafluoride (SF6) technique. In all experiments, ruminal fluid was collected via the mouth approximately four hours after the start of feeding. Seven prediction equations were tested. Methane yield (MY) was equally best predicted by the following equations: MY = 4.08 × (acetate/propionate) + 7.05; MY = 3.28 × (acetate + butyrate)/propionate + 7.6; MY = 316/propionate + 4.4. These equations were validated against independent published data from both dairy and beef cattle consuming a wide range of diets. A concordance of 0.62 suggests these equations may be applicable for predicting methane yield from all cattle and not just dairy cows, with root mean-square error of prediction of 3.0 g CH4/kg dry matter intake.

Coleus amboinicus (Lour.) leaves as a modulator of ruminal methanogenesis and biohydrogenation in vitro

Active plant metabolites (APM) are recognized as modifiers of ruminal microbial fermentation including methanogenesis and biohydrogenation of fatty acids (FA). Coleus amboinicus Lour. leaves (CAL) are rich in several APM, which could serve as ruminal fermentation modulators. A phytochemical analysis showed that CAL contain phenolic acids (10.4 mg·g-1 dry matter [DM]; high in rosmarinic acid), flavonoids (2.6 mg·g-1 DM), diterpenes (2 mg·g-1 DM), and linolenic acid (35.4 g (100 g)-1 FA). This study aimed to investigate the effect of CAL on ruminal methanogenesis and biohydrogenation as well as basic fermentation characteristics and microbial populations. The in vitro experiment was carried out using Hohenheim gas test system with 40 mL of buffered ruminal fluid incubated for 24 h at 39 °C in anaerobic conditions. Approximately 400 mg (DM basis) of total mixed ration (TMR) was used as a control substrate and the CAL substrate was used at doses of 10, 20, 40, and 80 mg DM replacing equal amounts of TMR. Addition of CAL decreased methane production up to 30% linearly as the amount of CAL increased (P < 0.05). In vitro dry matter digestibility and ammonia tended to increase with increasing doses of CAL. Concentration of total volatile fatty acids was not affected by the CAL although there appeared to be a minor positive linear trend; however, acetate, butyrate, and isobutyrate proportion increased quadratically (P < 0.001). CAL tended to linearly increase α-linolenic acid and conjugated linoleic acid as well as increased stearic acid concentration in buffered ruminal fluid. CAL particularly increased total protozoa and bacterial populations during fermentation, but inhibited methanogens. It is concluded that the CAL may be promising to be used as a feed additive to decrease methanogenesis as well as biohydrogenation of FA in the rumen.

Incremental amounts of Ascophyllum nodosum meal do not improve animal performance but do increase milk iodine output in early lactation dairy cows fed high-forage diets

The objective of this study was to investigate the effects of incremental amounts of Ascophyllum nodosum meal (ANOD) on milk production, milk composition including fatty acids and I, blood metabolites, and nutrient intake and digestibility in early lactation dairy cows fed high-forage diets. Twelve multiparous Jersey cows averaging (mean±standard deviation) 40±21 d in milk and 464±35 kg of body weight and 4 primiparous Jersey cows averaging 75±37 d in milk and 384±17kg of body weight were randomly assigned to treatment sequences in a replicated 4×4 Latin square design. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Cows were fed a total mixed ration (64:36 forage-to-concentrate ratio) supplemented (as fed) with 0, 57, 113, or 170 g/d of ANOD. Milk yield as well as concentrations and yields of milk components (fat, protein, lactose, milk urea N) were not affected by increasing dietary amounts of ANOD. Concentration (from 178 to 1,370 µg/L) and yield (from 2.8 to 20.6 mg/d) of milk I increased linearly in cows fed incremental amounts of ANOD as a result of the high concentration of I (820 mg/kg of dry matter) in ANOD. Overall, only minor changes were observed in the proportion of milk fatty acids with ANOD supplementation. Quadratic trends were observed for dry matter intake and total-tract digestibilities of organic matter and neutral detergent fiber, whereas negative linear trends were observed for serum concentration of cortisol and crude protein digestibility with ANOD supplementation. Serum concentrations of triiodothyronine and thyroxine were not affected by ANOD supplementation and averaged 1.1 and 48.4 ng/mL, respectively. However, feeding increasing amounts of ANOD linearly reduced the plasma concentration of nonesterified fatty acids (from 164 to 132 mEq/L). Quadratic effects were found for the total-tract digestibility of ADF and urinary output of purine derivatives, suggesting that ANOD supplementation may stimulate growth of ruminal cellulolytic bacteria in a dose-dependent fashion. In general, feeding incremental amounts of ANOD to early lactation dairy cows dramatically increased milk I concentration and output with no effect on animal performance.

Effect of low and high oil corn distillers' grain on rumen fermentation, growth performance and carcass characteristics of lambs

The objective of this study was to determine the effect of replacing a mixture of canola meal and barley grain in the diet with (low and high oil) corn dried distillers’ grains with solubles (DDGS) or wheat DDGS on rumen fermentation, feed intake, growth performance and carcass traits in lambs. Seventy Canadian Arcott lambs (24.7 ± 3.21 kg) were used in a completely randomised block design over a 14-week trial. Experimental diets were provided ad libitum as pelleted total mixed rations. In the treatment diets, canola meal and barley grain were replaced with 200 g/kg of dietary DM of either high oil corn DDGS, low oil corn DDGS or wheat DDGS. A positive control diet was added to match the lipid content of 39 g/kg DM of the high oil corn DDGS diet. An in vitro rumen digestibility trial was conducted using ruminal fluid obtained from three non-lactating Holstein dairy cows. Rumen contents were also collected from each lamb at the time of slaughter for testing in vivo rumen fermentation. Data from both the in vivo and in vitro results were analysed using the MIXED procedure of SAS. The in vitro incubations revealed both corn DDGS diets produced less microbial N and microbial DM than control and wheat DDGS diets; however, this difference was too minimal to affect growth performance. Similarly, there was no dietary effect on (P > 0.05) on in vivo ruminal fermentation or carcass characteristics (P ≥ 0.19) of the lambs. Lambs fed low oil corn DDGS had lower average daily gains (P < 0.03) than those fed either high oil corn DDGS or wheat DDGS however they did not differ from those fed the control. This research demonstrated that replacing canola meal and portions of barley grain with 200 g/kg DM of either high oil corn DDGS, low oil corn DDGS or wheat DDGS in finishing lamb ratios could effectively maintain healthy rumen function, growth performance and carcass characteristics.

VITAMIN REQUIREMENTS OF SEVERAL CELLULOLYTIC RUMEN BACTERIA

Scott, H. W. (Ohio Agricultural Experiment Station, Wooster), and B. A. Dehority. Vitamin requirements of several cellulolytic rumen bacteria. J. Bacteriol. 89:1169-1175. 1965.-Four strains of cellulolytic bacteria recently isolated from in vitro rumen fermentations were used in this study. Nine water-soluble vitamins were tested in single-deletion and single-addition plus biotin experiments, each with and without charcoal-extracted casein hydrolysate. Bacteroides succinogenes A3C and B21a required only biotin under the above experimental conditions. Ruminococcus flavefaciens B34b showed an absolute requirement for biotin and was stimulated by p-aminobenzoic acid (PABA) in the single-deletion experiments. In the single-addition plus biotin experiments, PABA and, to a lesser extent, vitamin B(12) appeared to be required for maximal growth. The presence or absence of casein hydrolysate did not affect the vitamin requirements for the aforementioned three strains. In the single-deletion experiments, R. flavefaciens Cla showed an absolute requirement for biotin and, when casein hydrolysate was omitted, for B(12). When casein hydrolysate was present, no requirement for B(12) could be observed. In the single-addition experiments where the basal medium contained biotin and casein hydrolysate or B(12), PABA was required for maximal growth; however, the single deletion of PABA caused only slight retardation of growth. Investigation of the B(12) or casein hydrolysate requirement of Cla revealed that a mixture of purified amino acids simulating casein hydrolysate satisfied this requirement. Subsequent work indicated that this requirement could be satisfied by the amino acid methionine.

Effects of feeding or infusing ammonium salts of volatile fatty acids on ruminal fermentation, plasma characteristics, and milk production of cows

Eight rumen-fistulated Holstein cows, averaging 77 d postpartum, were used in a replicated 4 X 4 Latin square design with 28-d periods to investigate the effect of ammonium salts of isobutyrate, 2-methylbutyrate, isovalerate, and n-valerate on animal performance and their possible mechanism(s) and site(s) of action. Each cow was fed ad libitum a complete mixed diet of 55% corn silage and 45% concentrate on a dry basis that was supplemented with 1.8 kg of premix daily. Treatments were 1) control, 2) ammonium salts of volatile fatty acids in premix, 3) ammonium salts of volatile fatty acids ruminally infused, or 4) ammonium salts of volatile fatty acids abomasally infused. Mean ruminal fluid pH and concentrations of ammonia and volatile fatty acids for treatment comparisons were not different. Plasma concentrations of isobutyrate, 2-methylbutyrate, and valerate differed among treatments, but there was no significant effect on dry matter intake, milk production, milk composition, or efficiency of feed utilization. Apparent nutrient digestibility; disappearance of dry matter, cellulose, and nitrogen from polyester bags suspended in the rumen; and plasma concentrations of glucose, free fatty acids, and growth hormone also were not significantly affected by treatment.

Chemical factors involved in ruminal fiber digestion

In the United States, cattle are commonly fed diets containing cereal grains. The presence of starch and sugars reduces fiber digestion, which may in turn depress intake. In this paper, chemical constraints that may be responsible for the decrease in fiber digestion are explored. A major factor appears to be rumen pH. Moderate depression in pH, to approximately 6.0, results in a small decrease in fiber digestion, but numbers of fibrolytic organisms are usually not affected. Further decreases to 5.5 or 5.0 result in depressed growth rates and decreased fibrolytic microbes, and fiber digestion may be completely inhibited. Proliferation of organisms on readily fermentable carbohydrates may increase the need for total nitrogen as both ammonia and amino acids. The value of amino acids to cellulolytic organisms appears to be primarily as sources of isobutyric, isovaleric, and 2-methylbutyric acids. This reinforces the need to establish dietary requirements for nonprotein nitrogen, degradable protein, and isoacids. Other factors affecting fiber digestion, such as inhibition of cellulytic enzymes and plant concentrations of lignins and phenyl propanoids, are also discussed.

Effect of carbon-4 and carbon-5 volatile fatty acids on growth of mixed rumen bacteria in vitro

Mixed ruminal bacteria (400 mg cells/liter) were incubated in artificial media containing ammonia, sodium carbonate, macrominerals, vitamins, sulfide, microminerals, acetate, propionate, and butyrate. When mixed carbohydrates (equal parts glucose, maltose, sucrose, cellobiose, and soluble starch) were added at 155 mg/liter per h for 10 h, average bacterial growth rate was slow, and dry weight yield was greater than 23%. Additions of isobutyrate, valerate, isovalerate, and 2 methylbutyrate had little influence on synthesis of bacterial dry weight, deoxyribonucleic acid, ribonucleic acid, or carbohydrate. When a timothy hay inoculum was used, isovalerate and 2 methyl-butyrate increased protein synthesis by 11.2 and 16.4%, but isobutyrate and valerate alone were without effect. All four acids combined increased bacterial protein by 18.7%. Responses with an inoculum of 60% concentrate and mixed hay were smaller and not statistically different from control incubations. Low concentrations of Trypticase (less than 250 mg/liter) improved efficiency of microbial protein synthesis from organic matter, but more was associated with decreased efficiency and utilization of extracellular ammonia.

Production responses of dairy cows fed diets supplemented with ammonium salts of iso C-4 and C-5 acids

A three-university study examined effects of ammonium salts of volatile fatty acids on dairy cows for a full lactation cycle. Objectives were a) to determine the most efficacious amount and ratio of two components, ammonium salts of C-5 acids and ammonium isobutyrate, and b) to compare responses of this optimum blend with the control in a response surface design. This design tested six blends of the two components defined by the center point and the five points of an equilateral pentagon from which response surfaces would be computed and a control. Each treatment consisted of 23 cows for a total of 161 multiparous Holstein cows. All cows were fed corn silage for ad libitum consumption, 1.8 kg of urea-mineral-vitamin-premix plus supplement based on corn grain and corn gluten meal according to milk production. Response surfaces, based on milk yield, defined an optimum blend composed of 61 g ammonium salts of C-5 acids plus 28 g ammonium isobutyrate per cow per day equivalent to 120 g aqueous blend (74% solids). The optimum blend was similar to the center point blend. Cows receiving the center point blend peaked higher and produced more milk, 4% fat-corrected milk, milk protein, and total solids than control cows. For the first trimester of lactation, milk yields for control and center point blend were 28.6 and 31.8 kg. The 305-day milk, 4% fat-corrected milk yields, and dry matter intakes (kg) were: control 20.5, 19.7, 17.3; center point blend 23.2, 21.6, 17.5. Increased milk production was associated with improved feed utilization. No effect on health or reproduction was observed.

Cecal microflora of turkeys fed low or high fiber diets: enumeration, identification, and determination of cellulolytic activity

Examination of cecal contents or bacterial cultures thereof from turkeys fed either a high fiber (HF) or low fiber (LF) ration indicated that direct microscopic counts of microbes were significantly higher in HF-fed than in LF-fed birds. There was no significant difference in mean colony counts between the two groups of turkeys. In both LF and HF-fed birds, 77% of the microbes were Gram-positive rods, 14% Gram-negative rods, and 9% Gram-positive cocci. The predominant microorganism was Eubacterium, but Lactobacillus, Peptostreptococcus, Escherichia coli, Propionibacterium, and Bacteriodes were also isolated. Percentages of Peptostreptococcus were significantly greater in HF-fed turkeys and of E. coli were significantly greater in LF-fed turkeys. Yeasts were routinely found in both LF and HF-fed birds, but protozoa were not isolated. Turkeys fed the HF diet harbored significantly higher numbers of facultative microorganisms than did LF-fed birds. In pure cultures from turkeys preconditioned to a HF diet, there was a nonsignificant trend toward greater cellulolysis than in pure cultures from LF-fed turkeys. In contrast, cellulolysis by mixed cultures from HF-fed birds was significantly greater than that in mixed cultures from LF-fed turkeys.

Effect of feeding isoacids with urea on growth and nutrient utilization by lactating cows

In the growth study 10 g each of isobutyrate, isovalerate, 2-methylbutyrate, n-valerate, and phenylacetate were mixed with 80 g of urea, 50 g of molasses, and 270 g of ground hay and fed to nine dairy heifers for 90 days. The control group was fed the same diet minus isoacids and phenylacetate. All animals were fed ad libitum timothy hay as the sole roughage. In the digestion trial, two mixtures of isoacids and a control ration were fed to nine lactating cows in a 3 X 3 Latin square design with 28-day feeding periods. Corn silage was the sole roughage, and concentrate was fed in proportion to milk production. Collection of feces and urine was for the last 5 days of each period. Mixture 1 of isoacids contained on a molar basis 28, 24, 24, and 24% of isobutyrate, isovalerate, 2-methylbutyrate, and n-valerate, respectively. Corresponding for mixture 2 were 36, 17, 17, and 30%. Addition of isoacids increased growth rate of younger animals but not older ones. The isoacid mixtures improved utilization of nitrogen by lactating cows. Urinary nitrogen decreased, and retention of absorbed nitrogen increased. Digestibility of dry matter and nitrogen were not affected by isoacid additions.

In vitro digestion of bloat-safe and bloat-causing legumes by rumen microorganisms: gas and foam production

Leaves of three bloat-safe legumes -- birdsfoot trefoil (Lotus corniculatus L.), sainfoin (Onobrychis viciaefolia Scop.), and cicer milkvetch (Astralagus cicer L.) -- and of three bloat-causing legumes -- alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and white clover (Trifolium repens L.) -- were incubated with strained rumen fluid or with mixed rumen fluid and solids. Gas released was measured during the early period (0 to 22 h) of this in vitro digestion. Gas volume was greater with a 1:1 (wt/vol) mixture of solid and fluid rumen contents than with rumen fluid alone. It was greater with whole and chewed leaves from the bloat-causing legumes than with whole leaves from the bloat-safe legumes. However, when leaves were homogenized, volumes of gas from bloat-causing and bloat-safe legumes were similar. More gas was released from homogenized leaves than from the same weight of whole leaves. The amount of foam produced on chewed herbage and homogenized leaves of bloat-causing legumes was greater than on those of bloat-safe legumes. These results are consistent with the rate of disintegration and digestion of legumes by rumen bacteria being an important determinant in pasture bloat. Measurement of gas produced early in in vitro digestion may provide a useful bioassay for evaluating the bloat-causing potential of legumes in breeding selections if variability of the method can be reduced.

[Isobutylidene-di-urea as a new NPN source for ruminants. 2. Metabolism of 14C-15N-isobutylidene-di-urea in sheep]

2 male sheep (weighing 45 kg and 44 kg) were fitted with a ruminal fistula and a jugular vein catheter and received isobutylidendi-urea for a 42-day period of adjustment. The diet contained 25% starch, 23.8% glucose, 29.0% cellulose, 10.0% straw, 1.7% sunflower seed oil, 4.3% isobutylidendi-urea, 5.6% minerals and vitamins. Each animal received 60 g of isobutylidendi-urea in daily amounts of 1.4 kg of the ration-4.4% of the total dietary N came from the straw. At the begin of the trial each sheep received 30 g of 14C15N isobutylidendi-urea (C1-siobutyl labelling) administered as a suspension. The animals were then placedin respiration cages. The peak of specific 14C activity in the expired air (including ruminal gas) was observed 2 hrs after the beginning of the trial. 18--30 hrs after the beginning of the trial the highest level of 15N incorporation into the TCE (trichloroacetic acid) soluble fraction of the ruminal fluid was noted resulting from the reflow of urea via the rumeno-hepatic circulatory system in the rumen. A high concentration of 15N was shown to be present, for prolonged period, in the TCE soluble fraction of the ruminal fluid (up to the 30 hr of experiment). The 15N concentration in the blood plasma (TCE soluble portion) was found to increase reaching a peak value 23 hrs after administration of the isotope. The highest level of 14C activity in this fraction appeared 1 hr after isotope administration. The 15N incorporation into the protein fraction of blood plasma reached a constant high level between the 29th and 47th hr of experiment. The highest 15N concentrations in urine were noted after 1 day. 3.5% of the administered dose of 14C activity and 23% of the supplied amount of N were excreted in the urine. 20% of the total amount of 15N excreted in the urine could be detected as 14C isobutyl residues. An excess of between 0.05 and 0.17 atom% of the isotopes were found in muscular tissue and in different organs of the sheep when these were slaughtered on the 7th day of experiment (liver: 0.17%, kidneys: 0.14%, muscle: 0.05%, heart: 0.08%). The results obtained in the present trial clearly indicate that ruminants are able to utilize nitrogen from isobutyldi-urea.