Rumen Microbial Protein Production Research Articles

3-Nitrooxypropanol substantially decreased enteric methane emissions of dairy cows fed true protein- or urea-containing diets

Methane is a potent but short-lived greenhouse gas targeted for short-term amelioration of climate change, with enteric methane emitted by ruminants being the most important anthropogenic source of methane. Ruminant production also releases nitrogen to the environment, resulting in groundwater pollution and emissions of greenhouse gas nitrous oxide. We hypothesized that inhibiting rumen methanogenesis in dairy cows with chemical inhibitor 3-nitrooxypropanol (3-NOP) would redirect metabolic hydrogen towards synthesis of microbial amino acids. Our objective was to investigate the effects of 3-NOP on methane emissions, rumen fermentation and nitrogen metabolism of dairy cows fed true protein or urea as nitrogen sources. Eight ruminally-cannulated cows were fed a plant protein or a urea-containing diet during a Control experimental period followed by a methanogenesis inhibition period with 3-NOP supplementation. All diets were unintentionally deficient in nitrogen, and diets supplemented with 3-NOP had higher fiber than diets fed in the Control period. Higher dietary fiber content in the 3-NOP period would be expected to cause higher methane emissions; however, methane emissions adjusted by dry matter and digested organic matter intake were 54% lower with 3-NOP supplementation. Also, despite of the more fibrous diet, 3-NOP shifted rumen fermentation from acetate to propionate. The post-feeding rumen ammonium peak was substantially lower in the 3-NOP period, although that did not translate into greater rumen microbial protein production nor lesser nitrogen excretion in urine. Presumably, because all diets resulted in low rumen ammonium, and intake of digestible organic matter was lower in the 3-NOP period compared to the Control period, the synthesis of microbial amino acids was limited by nitrogen and energy, precluding the evaluation of our hypothesis. Supplementation with 3-NOP was highly effective at decreasing methane emissions with a lower quality diet, both with true protein and urea as nitrogen sources.

Nature of Carbohydrates in Agro-industrial By-products (AIBP) Scarcely Support Rumen Microbial Protein Production but Sustain Milk Composition

Background: The microbial protein (MBP) production in rumen has quantitative influence on protein availability to host animal and also influence milk composition, particularly milk protein. Few native breeds produce low levels of milk that should sustain economically on agro-industrial by-products (AIBP). However, the nature of carbohydrates in AIBP how far support the MBP in rumen is seldom quantified. The objective of the study was to evaluate the cell wall carbohydrates of AIBP as a source of energy for rumen MBP production and milk composition in Bos indicus cows. Methods: Twenty Deoni breed cows in mid-lactation were divided in complete randomized block design into 5 groups of 4 each based on milk yield, body weight, parity and days in lactation. Basal roughage was finger millet straw ad-lib. The cows in treatment groups were supplemented with wheat bran (T1), or hyacinth bean grit (T2), or soy husk (T3), or 50% green gram grit plus 50% pigeon pea husk (T4) and compared with a control group (CG) supplemented with sorghum grain. All the supplements were made 18% isonitrogenous with commercial urea and fortified with 2% common salt and 3% minerals and vitamins mix. The diets were fed for 7 weeks including a digestibility trial of 5 days duration. Result: Total diet intake was comparable between CG and TGs. CP, hemicelluloses, celluloses (P≤0.01) and, EE (P≤0.05) digestibility were higher in TGs than CG. Energy efficiency was comparable between grain and AIBPs. Rumen MBP was lesser in TGs than CG. Higher rumen MBP among TGs was observed in T4 (180 g d-1) but it was 45 g d-1 lesser than CG. Milk total solids (TS), fat and solids-non-fat (SNF) were comparable between CG and TGs. The coefficient of variation in daily milk yield was reduced in TGs. The concentrate supplement with 50% grit and 50% husk combination was only suitable to moderately sustain rumen MBP production and also support milk production otherwise, AIBP as the sole concentrate supplement had limited benefit for rumen MBP production.

Optimized oral supplementation of vitamins improves feed intake and rumen microbial protein synthesis in Deoni cows

The present study was conducted to optimize oral doses of fat- and water-soluble vitamins in cattle using in vitro gas production model and to ascertain their effects on dry matter intake (DMI), nutrient digestibility, and rumen microbial protein (RMBP) synthesis. Doses optimized using the in vitro model were 3.66, 6.78, 16.3, 41.1, 3.87, 0.323, 4.12, and 0.055 mg/kg DMI, respectively, for thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid, and B12 and 500 IU/kg DMI for vitamin K. Thirty-two adult, nonproducing Deoni cows (375 ± 13.4 kg body weight, BW) were randomly divided into four equal groups (n = 8) and fed a basal diet (CON) or diets supplemented with in vitro optimized doses of water-soluble (WS), fat-soluble (FS), or both (WSFS) vitamins. The DMI values in WS and WSFS were higher than that of FS (92.6 and 96.17 vs. 82.85 g/kg BW0.75; P = 0.048) but comparable to CON (90.34 g/kg BW0.75). The purine derivative creatinine index was significantly higher in the WSFS group compared to CON (270.3 vs. 224.6; P = 0.035). Oral supplementation of optimized doses of vitamins as derived from in vitro trials improved DMI and RMBP production in Deoni cows.

The Concentrations of Rumen Fluid Volatile Fatty Acids and Ammonia, and Rumen Microbial Protein Production in Sheep Given Feed During the Day and Night Time

An experimental study was carried out to investigate the concentrations of volatile (VFA), ammonia and microbial protein production of rumen fluid in sheep given fedd during the day and at night. This study used 12 fat-tailed rams aged 12-18 months and weighed 24,12 ± 25 kg (CV = 10,51%). The rams were fed a complete feed containing 16.64% protein and 68,33% total digestible nutrients (TDN). The rams were allocated into a completely randomised design with 3 treatments and 4 replications. The treatments applied were: T1: day time feeding (6.00 hrs – 18.00 hrs); T2: night time feeding (18.00 hrs – 6.00 hrs); and T3: day and night time feedings (6.00 hrs – 6.00 hrs). The parameters observed were dry matter intake (DMI), rumen VFA concentration, rumen ammonia concentration, rumen rmicrobial protein production and the efficiency of rumen microbial protein production. The results showed that feeding time did not significantly affect (P>0.05) all the parameters observed. Dry matter intake, VFA concentration, ammonia concentration, the microbial protein production of rumen fluid and the efficiency of microbial protein production were 1,073g/d, 49.69 mmol; 4.77 mg N/100 ml, 12,111 g/d and 19.96 g per kg digestible organic matter intake (DOMI), respectively. It is concluded that feeding time did not affect DMI, condition of rumen fluid and rumen microbial protein production in sheep.

Microbial protein estimation in Murrah buffalo calves fed on diets with varying levels of energy and protein

A study was conducted to predict the effect of energy and protein levels in diet on rumen microbial protein production in Murrah buffalo calves. Microbial protein was estimated from urinary excretion of purine derivatives. Six diets were formulated to provide 90% (12.30% CP), 100% (13.70% CP), and 110% (15.15% CP) protein level, and 90% (2.20 Mcal ME/kg DM) and 110% (2.42 Mcal ME/kg DM) energy level of ICAR 2013 recommendations for buffalo calves. Thirty calves (body weight; 254±7.4 kg) were divided into 6 groups and fed in 2×3 factorial designs. Dry matter intake was recorded by feeding animals for experimental period of 150 days. At the end of feeding trial, urine samples were collected. Collection, preservation, analysis and calculation of urinary purine derivatives were performed by methods described by IAEA (1997). Allantoin constituted the principal PD in the urine. Allantoin and uric acid ranged from 19.93 to 21.37 mmol/day and 2.32 to 3.49 mmol/day, respectively. Total PD varied from 23.01 to 24.28 mmol/day, whereas PD per kg BW0.75 was within ranges of 362.77 to 384.23 mmol. The microbial N per kg DOMI or digestible OM retention (DOMR) was significantly higher in lower dietary energy group compared to higher ones. There was no significant effect of the energy and protein levels on allantoin, uric acid, creatinine, total purine derivatives and microbial N production per metabolic body weight (kg) in buffaloes. But microbial N production per digestible organic matter intake increased with decreased energy levels, whereas there was no significant effect of protein levels on it. Thus there was efficient conversion of feed N to microbial protein at CP of 12.3% and ME of 2.20 Mcal/kg DM in 250 kg BW Murrah buffaloes.

PEMANFAATAN SEMAK BUNGA PUTIH (Chromolaena odorata) SEBAGAI PAKAN LOKAL SUMBER PROTEIN UNTUK TERNAK SAPI: KONSUMSI, DAYA CERNA DAN FERMENTASI RUMEN

Chromolaena odorata (CO) contains high protein (21-36%) and has the potency to be utilized as a cheap protein source for livestock due to its abundants availability. However, it also contain secondary metabolic compounds that could has a negative effects on livestock, hence it requires treatments to eliminate the antinutrient compounds. One of the methods is pelleting. This experiment aimed at assessing the efficacy of chromolaena level in pelleted ration for fattened cattle. Four bali young male aged ± 2 years old were allotted into four dietary treatments in a latin square experimental design. The treatments were pellet contains CO at a level of 10% (COP10) or 20% (COP20), or 30% (COP30) or 40% (COP40). The pellet was offered at 2% live weight (LW), and kume grass hay was provided ad libitum as basal diet. The pellet was iso energy (11.5 MJ ME/kg DM) and nitrogenous (20% CP). Parameters measured were dietary intake and digestibility, rumen fermentation, and rumen microbial protein production. The results showed that increasing level of chromolaena to 40% in the pellet significantly surpressed most of the measured parameters. Dry matter intake declined from 2.5% LW in treatment COP10 to 2.19% LW in COP40. Similarly, crude protein intake reduced from 749 g/d (COP10) to 661 g/d (COP40). Unaffected parameters were digestibility, rumen ammonia concentration (116-125 mg/dL),total VFA, and efficiency of rumen microbial protein synthesis (60,4-73,4 g/kg BOT). It is concluded that chromolaena can be utilized as protein source for ruminants, yet it tends to depress intake at high level of inclusion (40%). On the other hand, dietary digestibility and rumen function were not effected by level of chromolaean, though efficiency of rumen microbial protein synthesis was lower than the recommended values in the exisiting feeding standards. Therefore, further research is warrant to devise appriate treatments to improve feeding value of chromolaena as cheap protein source for livestock.Key words: Chromolaeana odorata, protein, intake, rumen microbial protein, cattle

Production attributes of Merino sheep genetically divergent for wool growth are reflected in differing rumen microbiotas

Divergent genetic selection for wool growth as a single trait has led to major changes in sheep physiology and metabolism, including variations in rumen microbial protein production and uptake of α-amino nitrogen in portal blood. This study was conducted to determine if sheep with different genetic merit for wool growth exhibit distinct rumen bacterial diversity. Eighteen Merino wethers were separated into groups of contrasting genetic merit for clean fleece weight (CFW; low: WG− and high: WG+) and fed a blend of oaten and lucerne chaff diet at two levels of intake (LOI; 1 or 1.5 times maintenance energy requirements) for two seven-week periods in a crossover design. Bacterial diversity in rumen fluid collected by esophageal intubation was characterized using 454 amplicon pyrosequencing of the V3/V4 regions of the 16S rRNA gene. Bacterial diversity estimated by Phylogenetic distance, Chao1 and observed species did not differ significantly with CFW or LOI; however, the Shannon diversity index differed (P=0.04) between WG+ (7.67) and WG− sheep (8.02). WG+ animals had a higher (P=0.03) proportion of Bacteroidetes (71.9% vs 66.5%) and a lower (P=0.04) proportion of Firmicutes (26.6% vs 31.6%) than WG− animals. Twenty-four specific operational taxonomic units (OTUs), belonging to the Firmicutes and Bacteroidetes phyla, were shared among all the samples, whereas specific OTUs varied significantly in presence/abundance (P<0.05) between wool genotypes and 50 varied (P<0.05) with LOI. It appears that genetic selection for fleece weight is associated with differences in rumen bacterial diversity that persist across different feeding levels. Moderate correlations between seven continuous traits, such as methane production or microbial protein production, and the presence and abundance of 17 OTUs were found, indicating scope for targeted modification of the microbiome to improve the energetic efficiency of rumen microbial synthesis and reduce the greenhouse gas footprint of ruminants.

Maximizing efficiency of rumen microbial protein production.

Rumen microbes produce cellular protein inefficiently partly because they do not direct all ATP toward growth. They direct some ATP toward maintenance functions, as long-recognized, but they also direct ATP toward reserve carbohydrate synthesis and energy spilling (futile cycles that dissipate heat). Rumen microbes expend ATP by vacillating between (1) accumulation of reserve carbohydrate after feeding (during carbohydrate excess) and (2) mobilization of that carbohydrate thereafter (during carbohydrate limitation). Protozoa account for most accumulation of reserve carbohydrate, and in competition experiments, protozoa accumulated nearly 35-fold more reserve carbohydrate than bacteria. Some pure cultures of bacteria spill energy, but only recently have mixed rumen communities been recognized as capable of the same. When these communities were dosed glucose in vitro, energy spilling could account for nearly 40% of heat production. We suspect that cycling of glycogen (a major reserve carbohydrate) is a major mechanism of spilling; such cycling has already been observed in single-species cultures of protozoa and bacteria. Interconversions of short-chain fatty acids (SCFA) may also expend ATP and depress efficiency of microbial protein production. These interconversions may involve extensive cycling of intermediates, such as cycling of acetate during butyrate production in certain butyrivibrios. We speculate this cycling may expend ATP directly or indirectly. By further quantifying the impact of reserve carbohydrate accumulation, energy spilling, and SCFA interconversions on growth efficiency, we can improve prediction of microbial protein production and guide efforts to improve efficiency of microbial protein production in the rumen.

Measurement of Microbial Protein Supply in Murrah Buffaloes (Bubalus bubalis) Using Urinary Purine Derivatives Excretion and PDC Index

A study was conducted to predict the rumen microbial protein production based on urinary excretion of purine derivatives in buffaloes fed a diet of wheat straw and concentrate (40:60) at four fixed levels of feed intake. (95, 80, 60 and 40% of preliminary voluntary feed intake) following experimental protocol of IAEA (Phase I). The buffaloes were allocated according to a 4×4 latin square design. The urinary allantoin, uric acid, total PD excretion (mmol/d) in treatments L-95, L-80, L-60 and L-40 was 20.13, 16.00, 12.96 and 9.17; 1.88, 2.12, 2.11 and 2.15; 22.01, 18.12, 15.07 and 11.32, respectively and were significantly (p<0.05) different among treatments except for uric acid. The rate of PD excretion (mmol/d) was positively correlated with the digestible organic matter intake. Variations were observed in PD and creatinine concentration in spot samples collected at 6-hour interval. However, daily PD:Creatinine ratio (PDC index) appears to be a reasonably good predictor of microbial-N supply. The contribution of basal purine excretion to total excretion of purine derivatives (PD) was determined in pre-fasting period followed by a fasting period of 6 d (Phase II). Daily PD and creatinine excretion (mmol/kg W 0.75 ) during fasting averaged 0.117 and 0.456 respectively for buffaloes. The excretion rates of PD decreased significantly (p<0.01) during fasting compare to pre-fasting period, the urinary creatinine excretion remained almost similar. Except for creatinine, plasma concentration of target parameters significantly (p<0.01) declined during fasting. Likewise, glomerular filtration rate (GFR) and renal clearance of allantoin and uric acid also decreased. Based on the PD excretion rates during fasting and at different levels of feed intake obtained in this study, a relationship between daily urinary PD excretion (Y-mmol) and microbial purine absorption (X-mmol) was developed for buffaloes as Y = 0.74X+0.117 kg W 0.75 . The microbial N supply (g/kg DOMI) remained statistically similar irrespective of dietary treatment. The results showed that excretion of urinary purine derivatives is positively correlated with the levels of feed intake in Murrah buffaloes and thus, estimation of urinary purine derivatives and PDC index could be used to determine microbial nitrogen supply when there is large variation in level of feed intake. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 3 : 347-355)

Effect of Abomasal Pectin Infusion on Digestion and Nitrogen Balance in Lactating Dairy Cows

Two experiments were conducted to test the hypothesis that increasing carbohydrate fermentation in the large intestine would increase intestinal conversion of blood urea N to microbial protein, thereby reducing urinary N output. In experiment 1, 3 multiparous Holstein cows were used in an incomplete 4×4 Latin square with 14-d periods. Cows were fed the same basal diet and treatments were the abomasal infusion of 0, 0.5, or 1kg/d of citrus pectin, or the addition of 1kg/d of molasses to the basal diet. Experiment 2 used 6 cows in a double reversal design with four 21-d periods. Cows were fed one basal diet and treatments were the abomasal infusion of either 0 or 1kg/d of pectin. In experiment 1, pectin infusion linearly decreased basal ration intake from 25.0 to 23.2kg/d. This was prevented in experiment 2 by restricted feeding, and basal ration intake was 22.2kg/d. Abomasal pectin caused numeric decreases in total tract apparent digestibility of neutral detergent fiber and neutral detergent solubles in experiment 1 and significantly decreased starch digestibility in experiment 2, suggesting that pectin may have reduced postruminal nutrient digestibility. Pectin infusion did not affect milk yield but decreased milk fat percentage from 3.69 to 3.53% in experiment 2. Increasing abomasal pectin tended to decrease urinary N and increase fecal N in experiment 1 and these effects were significant in experiment 2. For both experiments, urinary N decreased 26g/d, approximately 10% of daily urine N output. Abomasal pectin did not affect fecal pH or DM content; however, in experiment 2, pectin decreased fecal ammonia from 19.8 to 13.4mmol/kg of DM and increased fecal purines from 13.8 to 15.8mmol/kg of DM. In both experiments, excretion of fecal purines was increased from 15g/d for 0kg/d pectin to 18g/d for 1kg/d pectin, although this increase was only significant in experiment 2. These results suggest that manipulating dairy diets to increase postruminal fermentation may reduce urinary N and consequently manure ammonia losses. However, abomasal pectin tended to decrease both ruminal ammonia concentration and urinary purine derivative output in experiment 2, suggesting that postruminal pectin fermentation may have compromised rumen microbial protein production.

Digesta flow and rumen microbial protein production in ewes grazing perennial ryegrass

Herbage organic matter (OM) intakes and the abomasal flows of OM, non-ammonia nitrogen (NAN) and microbial nitrogen (MN) were estimated in ewes grazing perennial ryegrass during lactation in spring/summer (Group 1) or in autumn after the end of lactation (Group 2). On average, ewes in Group 1 consumed 804 g OM/day more than ewes in Group 2, while their daily abomasal flows of OM, NAN and MN were, respectively, 372, 28.8 and 26.7 g/day more than those in Group 2 ewes. The regression equations relating the flows of digesta or digesta components to OM intake were significantly different between the two groups of ewes. Rumen ammonia and volatile fatty acid levels were significantly higher in Group 1 ewes, though ewes in Group 2 had significantly higher molar proportions of acetate and significantly lower proportions of butyrate and especially propionate. Ewes in Group 1 had significantly faster CrEDTA fractional disappearance rates (FDR) (0.1474 h-l) than ewes in Group 2 (0.0847 h-l). The efficiency of microbial protein synthesis in Group 1 ewes was consistent with published values and was almost twice that estimated in Group 2 ewes. Results are presented to suggest that the observed differences between the two groups or ewes are not due to an effect of lactation, but to differences in the composition of the consumed herbage in autumn compared with spring/summer. It is argued that the observed differences in rumen fermentation pattern between the two groups of ewes reflect underlying differences in the water-soluble carbohydrate content of the consumed herbage. The inclusion, in multiple regression analyses, of either rumen propionate or rumen acetate : propionate ratio, together with OM intake explained approximately 0.80-0.85 of the variance in NAN or MN flows, reduced residual standard deviations compared with fitting OM intake alone, and removed the difference between the two groups of ewes. Inclusion of the CrEDTA FDR contributed no further explanation of the variance in the above flows.

Nitrogen levels in low-roughage diets for efficient rumen microbial protein production

The influence of dietary nitrogen (N) available in the rumen on the efficiency of microbial protein production was examined for 43 predominantly low-roughage diets given to cattle or sheep with rumen and duodenal (re-entrant) cannulae. The minimum amount of available N required for efficient microbial protein production was 2.0 g/100 g of organic matter actually digested in the rumen. When the diet supplied 2.7 g of available N/100 g of organic matter actually digested in the rumen, there was no net utilisation of recycled N. From this information, concentrations of N in organic matter required in low-roughage diets differing in organic matter digestibility and availability of dietary N have been calculated. Also a method of calculating the quantities of amino acid N and of particular amino acids absorbed from the small intestine from a knowledge of the diet composition is presented.

Effect of ammonia concentration of rumen microbial protein production in vitro.

1. The effect of ammonia concentration on microbial protein production was determined in continuous-culture fermentors charged with ruminal contents obtained from steers fed on either a protein-free purified diet, a maize-based all-concentrate diet, or a forage–concentrate (23:77) diet. Urea was infused into the fermentors to maintain various concentrations of ammonia in the incubating mixtures.2. Under nitrogen-limiting conditions, microbial protein yield measured as tungstic acid-precipitable N (TAPN) increased linearly with supplementary urea until ammonia started to accumulate in the incubating ingesta. Increasing the ammonia concentration beyond 50 mg NH3-N/l had no effect on microbial protein production.3. The molar proportions of volatile acids produced were not affected by the level of urea supplementation. Total acid production was decreased slightly under N-limiting conditions, but not to the same extent as microbial protein production.4. Estimated yield of microbial dry matter/mol ATP produced averaged 15·6 when non-limiting N as urea was provided with the purified diet.5. These results suggest that addition of non-protein N supplements to ruminant rations are warranted only if the prevailing concentration of ruminal ammonia is less than 50 mg NH3-N/l ruminal fluid.