Feeding 3-nitrooxypropanol reduces methane emissions by feedlot cattle on tropical conditions

Our objective was to evaluate the effects of feeding 3-nitrooxypropanol (3-NOP; Bovaer, DSM Nutritional Products) at two levels on methane emissions, nitrogen balance, and performance by feedlot cattle. In experiment 1, a total of 138 Nellore bulls (initial body weight, 360 ± 37.3 kg) were housed in pens (27 pens with either 4 or 5 bulls per pen) and fed a high-concentrate diet for 96 d, containing 1) no addition of 3-NOP (control), 2) inclusion of 3-NOP at 100 mg/kg dry matter (DM), and 3) inclusion of 3-NOP at 150 mg/kg DM. No adverse effects of 3-NOP were observed on DM intake (DMI), animal performance, and gain:feed (P > 0.05). In addition, there was no effect (P > 0.05) of 3-NOP on carcass characteristics (subcutaneous fat thickness and rib eye area). In experiment 2, 24 bulls (initial BW, 366 ± 39.6 kg) housed in 12 pens (2 bulls/pen) from experiment 1 were used for CH4 measurements and nitrogen balance. Irrespective of the level, 3-NOP consistently decreased (P < 0.001) animals' CH4 emissions (g/d; ~49.3%), CH4 yield (CH4/DMI; ~40.7%) and CH4 intensity (CH4/average daily gain; ~38.6%). Moreover, 3-NOP significantly reduced the gross energy intake lost as CH4 by 42.5% (P < 0.001). The N retention: N intake ratio was not affected by 3-NOP (P = 0.19). We conclude that feeding 3-NOP is an effective strategy to reduce methane emissions, with no impairment on feedlot cattle performance.

Effects of 3-nitrooxypropanol on enteric methane production, rumen fermentation, and feeding behavior in beef cattle fed a high-forage or high-grain diet1

The objective of the study was to determine whether feeding a diet supplemented with 3-nitrooxypropanol (3-NOP) affects feeding behavior altering intake and rumen fermentation. Two experiments were conducted with 9 rumen-cannulated beef steers in a replicated 3 × 3 Latin square design where animals received a high-forage or high-grain diet. Treatments were 1) a basal diet (CON), the CON diet supplemented with 3-NOP (dNOP; 100 mg/kg in dietary DM or 1 g/d), or the CON diet with 3-NOP (1 g/d) infused into the rumen (infNOP). Each experimental period consisted of 14-d diet adaptation and 7-d sample collection. A 7-d washout period was provided between experiment periods. All data were analyzed as a Latin square design using Mixed Procedure of SAS. In Exp. 1 (high-forage diet), methane yield (measured by the Greenfeed system) was lowered by 18% (18.6 vs. 22.7 g/kg DMI; P < 0.01) by dNOP compared with CON. Rumen fermentation was altered similarly by both NOP treatments compared with CON where dNOP and infNOP increased (P < 0.01) rumen pH at 3 h and decreased (P < 0.01) proportion of acetate in total VFA. However, DMI, feed consumption rate (0 to 3, 3 to 6, 6 to 12, and 12 to 24 h after feeding), particle size distribution of orts, and feeding behavior (videotaped for individual animals over 48 h) were not affected by dNOP and infNOP compared with CON. In Exp. 2 (high-grain diet), methane production was not affected by dNOP or infNOP compared with CON. Dry matter intake, feed consumption rate, particle size distribution of orts, and feeding behavior were not altered by dNOP and infNOP compared with CON. However, both dNOP and infNOP affected rumen fermentation where total VFA decreased (P = 0.04) and acetate proportion in total VFA tended to decrease (P = 0.07) compared with CON. In conclusion, dietary supplementation of 3-NOP did not affect feeding behavior of beef steers fed a high-forage or high-grain diet. However, rumen fermentation was similarly changed when 3-NOP was provided in the diet or directly infused in the rumen. Thus, observed changes in rumen fermentation with 3-NOP were not due to changes in feeding behavior indicating no effects on the organoleptic property of the diets. In addition, according to small or no changes in DMI in both experiments and relatively small changes in rumen fermentation in Exp. 2, a greater dosage level of 3-NOP than 100 mg/kg (dietary DM) may need further examination of its effects on feeding behavior of beef cattle.

The combined effects of supplementing monensin and 3-nitrooxypropanol on methane emissions, growth rate, and feed conversion efficiency in beef cattle fed high-forage and high-grain diets

The study objective was to evaluate the combined effects of supplementing monensin (MON) and the methane (CH4) inhibitor 3-nitrooxypropanol (NOP) on enteric CH4 emissions, growth rate, and feed conversion efficiency of backgrounding and finishing beef cattle. Two hundred and forty crossbred steers were used in a 238-d feeding study and fed a backgrounding diet for the first 105 d (backgrounding phase), transition diets for 28 d, followed by a finishing diet for 105 d (finishing phase). Treatments were as follows: 1) control (no additive); 2) MON (monensin supplemented at 33 mg/kg DM; 3) NOP (3-nitrooxypropanol supplemented at 200 mg/kg DM for backgrounding or 125 mg/kg DM for finishing phase); and 4) MONOP (33 mg/kg DM MON supplemented with either 200 mg/kg DM or 125 mg/kg DM NOP). The experiment was a randomized complete block (weight: heavy and light) design with 2 (NOP) × 2 (MON) factorial arrangement of treatments using 24 pens (8 cattle/pen; 6 pens/treatment) at the main feedlot and 8 pens (6 cattle/pen; 2 pens/treatment) at the controlled environment building (CEB) feedlot. Five animals per treatment were moved to chambers for CH4 measurements during both phases. Data were analyzed using a Mixed procedure of SAS with pen as experimental unit (except CH4). Location (Main vs. CEB) had no significant effect and was thus omitted from the final model. Overall, there were few interactions between MON and NOP indicating that the effects of the 2 compounds were independent. When cattle were fed the backgrounding diet, pen DMI was decreased by 7%, whereas gain-to-feed ratio (G:F) was improved by 5% with NOP supplementation (P < 0.01). Similarly, MON improved G:F ratio by 4% (P < 0.01), but without affecting DMI. During the finishing phase, DMI tended (P = 0.06) to decrease by 5% with both MON (5%) and NOP (5%), whereas ADG tended (P = 0.08) to decrease by 3% with MON. Gain-to-feed ratio for finishing cattle was improved with NOP by 3% (P < 0.01); however, no effects were observed with MON. 3-Nitrooxypropanol decreased CH4 yield (g/kg DMI) by 42% and 37% with backgrounding and finishing diets (P ≤ 0.01), respectively, whereas MON did not lower CH4 yield. Overall, these results demonstrate efficacy of NOP in reducing enteric CH4 emissions and subsequently improving feed conversion efficiency in cattle fed high-forage and high-grain diets. Furthermore, effects of NOP did not depend on whether MON was included in the diet.

Rapid Communication: Evaluation of methane inhibitor 3-nitrooxypropanol and monensin in a high-grain diet using the rumen simulation technique (Rusitec)

The objective of this study was to evaluate the effects of 3-nitrooxypropanol (NOP), a known methane (CH) inhibitor; the ionophore monensin (MON); and their combination on in vitro CH production in a high-grain diet (85% barley grain, 10% barley silage, and 5% vitamin-mineral supplement; DM basis) using a rumen simulation technique (Rusitec). Sixteen fermentation vessels in 2 Rusitec apparatuses (blocks) were used in a completely randomized block design with 4 treatments: Control, NOP (200 µg/g DM), MON (200 µg/g DM), and the combination of 200 µg NOP/g DM and 200 µg MON/g DM (NOP + MON). Two fermenters within each apparatus were randomly assigned to a treatment. Treatments were mixed with 10 g of substrate and supplied on a daily basis. The study included an 8-d adaptation period without treatment supplementation and a 6-d period for addition of treatments. Dry matter disappearance, pH, and total VFA were not affected by treatment ( ≥ 0.34). Acetate proportion was decreased by 8.3% and 14.9% with NOP and NOP + MON ( < 0.01), respectively; however, propionate proportion was not affected by treatment ( = 0.44). The acetate to propionate ratio was lowered by 21.1% with the combination of NOP and MON ( = 0.02), whereas ammonia-N concentration was not affected by treatment ( = 0.50). Total gas production was unaffected ( = 0.50), but CH production decreased by 77.7% and 75.95% ( < 0.01) with NOP and NOP + MON addition, respectively. Concurrently, H gas production increased by 131.3% and 185.6% ( = 0.01) with NOP and NOP + MON treatments, respectively. The copy number of methanogens was decreased in both solid and liquid phases ( < 0.01) with NOP and NOP + MON treatments. Despite the combination of NOP + MON showing the greatest decrease in acetate molar proportion and acetate to propionate ratio, it did not further inhibit CH beyond the effect of NOP alone. The decrease in CH emissions with treatments that included NOP occurred along with a decrease in the copy number of methanogens associated with the solid and liquid phases, confirming the inhibitory effects of NOP on these microorganisms. In conclusion, the combined effects of NOP and MON on CH mitigation did not exceed the effect of NOP alone when using a high-grain diet in vitro.

The potential of 3-nitrooxypropanol to lower enteric methane emissions from beef cattle

This study evaluated if 3-nitrooxypropanol reduces enteric methane (CH4) emissions when added to the diet of beef cattle. The effects of 3-nitrooxypropanol on related variables including diet digestibility, ruminal fermentation, and ruminal microorganisms were also investigated. Eight ruminally cannulated Angus heifers (549 ± 64.3 kg [mean BW ± SD]) were fed a high forage diet (backgrounding diet) supplemented with 4 levels of 3-nitrooxypropanol (0, 0.75, 2.25 and 4.50 mg/kg BW). The experiment was designed as a duplicated 4 × 4 Latin square with 2 groups of heifers and four 28-d periods. Methane emissions were measured during 3 consecutive days using metabolic chambers. Up to a 5.8% reduction in ad libitum DMI was observed when 2.5 mg/kg BW of 3-nitrooxypropanol was fed (P = 0.03). Increasing level of 3-nitrooxypropanol linearly (P < 0.001) reduced CH4, with 33% less CH4 (corrected for DMI) at the highest level of supplementation compared with the control. Feed energy lost as CH4 was also reduced when 3-nitrooxypropanol was supplemented (P < 0.001). Molar proportion of acetate was reduced (P < 0.001) and that for propionate increased (P < 0.001) with increasing dose of 3-nitrooxypropanol, which in turn led to a reduction in the acetate to propionate ratio (P < 0.001). Total copy numbers of 16S ribosomal RNA (rRNA) genes for bacteria, methanogens, and 18S rRNA genes for protozoa in ruminal contents were not affected by 3-nitrooxypropanol supplementation (P ≥ 0.31). There was no effect of 3-nitrooxypropanol on DM (P = 0.1) digestibility in the total tract. The use of 4.5 mg/kg BW of 3-nitrooxypropanol in beef cattle consuming a backgrounding diet was effective in reducing enteric CH4 emissions without negatively affecting diet digestibility.

Effect of a blend of essential oil compounds on the colonization of starch-rich substrates by bacteria in the rumen

AIMS

To investigate the mode of action of a blend of essential oil compounds on the colonization of starch-rich substrates by rumen bacteria.

METHODS AND RESULTS

Starch-rich substrates were incubated, in nylon bags, in the rumen of sheep organized in a 4 x 4 latin square design and receiving a 60:40 silage : concentrate diet. The concentrate was either high or low in crude protein, and the diet was supplemented or not with a commercial blend of essential oil compounds (110 mg per day). The total genomic DNA was extracted from the residues in the bags. The total eubacterial DNA was quantified by real-time PCR and the proportion of Ruminobacter amylophilus, Streptococcus bovis and Prevotella bryantii was determined. Neither the supplementation with essential oil compounds nor the amount of crude protein affected the colonization of the substrates by the bacteria quantified. However, colonization was significantly affected by the substrate colonized.

CONCLUSIONS

The effect of essential oils on the colonization of starch-rich substrates is not mediated through the selective inhibition of R. amylophilus.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study enhances our understanding of the colonization of starch-rich substrates, as well as of the mode of action of the essential oils as rumen manipulating agents.

Effect of triacylglycerol structure on absorption and metabolism of isotope-labeled palmitic and linoleic acids by humans

The effect of dietary TAG structure and fatty acid acyl TAG position on palmitic and linoleic acid metabolism was investigated in four middle-aged male subjects. The study design consisted of feeding diets containing 61 g/d of native lard (NL) or randomized lard (RL) for 28 d. Subjects then received an oral dose of either 1,3-tetradeuteriopalmitoyl-2-dideuteriolinoleoyl-rac-glycerol or a mixture of 1,3-dideuteriolinoleoyl-2-tetradeuteriopalmitoyl-rac-glycerol and 1,3-hexadeuteriopalmitoyl-2-tetradeuteriolinoleoyl-rac-glycerol. Methyl esters of plasma lipids isolated from blood samples drawn over a 2-d period were analyzed by GC-MS. Results showed that absorption of the 2H-fatty acids (2H-FA) was not influenced by TAG position. The 2H-FA at the 2-acyl TAG position were 85+/-4.6% retained after absorption. Substantial migration of 2H-16:0 (31.2+/-8.6%) from the sn-2 TAG position to the sn-1,3 position and 2H-18:2n-6 (52.8+/-6.4%) from the sn-1,3 position to the sn-2 position of chylomicron TAG occurred after initial absorption and indicates the presence of a previously unrecognized isomerization mechanism. Incorporation and turnover of the 2H-FA in chylomicron TAG, plasma TAG, and plasma cholesterol esters were not influenced by TAG acyl position. Accretion of 2H-16:0 from the sn-2 TAG position in 1-acylphosphatidylcholine was 1.7 times higher than 2H-16:0 from the sn-1,3 TAG positions. Acyl TAG position did not influence 2H-18:2n-6 incorporation in PC. The concentration of 2H-18:2n-6-derived 2H-20:4n-6 in plasma PC from subjects fed the RL diet was 1.5 times higher than for subjects fed the NL diet, and this result suggests that diets containing 16:0 located at the sn-2 TAG position may inhibit 20:4n-6 synthesis. The overall conclusion is that selective rearrangement of chylomicron TAG structures diminishes but does not totally eliminate the metabolic and physiological effects of dietary TAG structure.

Bioactive crude plant seed extracts from the NCAUR oilseed repository

Over four-hundred crude extracts from 202 plant species distributed among 131 plant families were evaluated for their bioactivity against brine shrimp (Artemia salina). Activity was determined for both the organic (CH2Cl2:MeOH) and aqueous extracts against A. salina in a 96 well-plate assay. Of the greater than four-hundred extracts tested, 21 organic and 6 aqueous extracts demonstrated potent cytotoxic activity (LC50 = < 100 microg/ml). Three of these organic extracts (Crateva religiosa, Diospyros dichrophylla, and Olax subscorpioidea) were chosen for chemical investigations due to their high activity and a lack of prior investigations. Chemical analysis of these extracts resulted in the isolation of oleanolic acid (1) and 4-epi-hederagenin (2) from C. religiosa, isodiospyrin (3) from D. dichrophylla, and santalbic acid (4) from O. subscorpioidea.

Effect of dietary docosahexaenoic acid on desaturation and uptake in vivo of isotope-labeled oleic, linoleic, and linolenic acids by male subjects

The effect of dietary docosahexaenoic acid (22:6n-3, DHA) on the metabolism of oleic, linoleic, and linolenic acids was investigated in male subjects (n = 6) confined to a metabolic unit and fed diets containing 6.5 or <0.1 g/d of DHA for 90 d. At the end of the diet period, the subjects were fed a mixture of deuterated triglycerides containing 18:1n-9[d6], 18:2n-6[d2], and 18:3n-3[d4]. Blood samples were drawn at 0, 2, 4, 6, 8, 12, 24, 48, and 72 h. Methyl esters of plasma total lipids, triglycerides, phospholipids, and cholesterol esters were analyzed by gas chromatography-mass spectrometry. Chylomicron triglyceride results show that the deuterated fatty acids were equally well absorbed and diet did not influence absorption. Compared to the low-DHA diet (LO-DHA), clearance of the labeled fatty acids from chylomicron triglycerides was modestly higher for subjects fed the high DHA diet (HI-DHA). DHA supplementation significantly reduced the concentrations of most n-6[d2] and n-3[d4] long-chain fatty acid (LCFA) metabolites in plasma lipids. Accumulation of 20:5n-3[d4] and 22:6n-3[d4] was depressed by 76 and 88%, respectively. Accumulations of 20:3n-6[d2] and 20:4n-6[d2] were both decreased by 72%. No effect of diet was observed on acyltransferase selectivity or on uptake and clearance of 18:1n-9[d6], 18:2n-6[d2], and 18:3n-3[d4]. The results indicate that accumulation of n-3 LCFA metabolites synthesized from 18:3n-3 in typical U.S. diets would be reduced from about 120 to 30 mg/d by supplementation with 6.5 g/d of DHA. Accumulation of n-6 LCFA metabolites synthesized from 18:2n-6 in U.S. diets is estimated to be reduced from about 800 to 180 mg/d. This decrease is two to three times the amount of n-6 LCFA in a typical U.S. diet. These results support the hypothesis that health benefits associated with DHA supplementation are the combined result of reduced accretion of n-6 LCFA metabolites and an increase in n-3 LCFA levels in tissue lipids.

Effect of dietary arachidonic acid on metabolism of deuterated linoleic acid by adult male subjects

The influence of dietary supplementation with 20:4n-6 on uptake and turnover of deuterium-labeled linoleic acid (18:2n-6[d2]) in human plasma lipids and the synthesis of desaturated and elongated n-6 fatty acids from 18:2n-6[d21 were investigated in six adult male subjects. The subjects were fed either a high-arachidonic acid (HIAA) diet containing 1.7 g/d or a low-AA (LOAA) diet containing 0.21 g/d of AA for 50 d. Each subject was then dosed with about 3.5 g of 18:2n-6[d2] as the triglyceride (TG) at 8:00 A.M., 12:00, and 5:00 P.M. The total 18:2n-6[d21] fed to each subject was about 10.4 g and is approximately equal to one-half of the daily intake of 18:2n-6 in a typical U.S. male diet. Nine blood samples were drawn over a 96-h period. Methyl esters of plasma total lipid (TL), TG, phospholipid, and cholesterol ester were analyzed by gas chromatography-mass spectroscopy. Dietary 20:4n-6 supplementation did not affect uptake of 18:2n-6[d2] in plasma lipid classes over the 4-d study period nor the estimated half-life of 24-36 h for 18:2n-6[d2]. The percentages of major deuterium-labeled desaturation and elongation products in plasma TL, as a percentage of total deuterated fatty acids, were 1.35 and 1.34% 18:3n-6[d2]; 0.53 and 0.50% 20:2n-6[d2]; 1.80 and 0.92% 20:3n-6[d2] and 3.13 and 1.51% 20:4n-6[d2] for the LOAA and HIAA diet groups, respectively. Trace amounts (<0.1%) of the 22:4n-6[d2] and 22:5n-6[d2] metabolites were present. Plasma TL concentration data for both 20:3n-6[d2] and 20:4n-6[d2] were 48% lower (P < 0.05) in samples from the HIAA diet group than in samples from the LOAA diet group. For a normal adult male consuming a typical U.S. diet, the estimated accumulation in plasma TL of 20:4n-6 synthesized from 20 g/d (68 mmole) of 18:2n-6 is 677 mg/d (2.13 mmole). Dietary supplementation with 1.5 g/d of 20:4n-6 reduced accumulation of 20:4n-6 synthesized from 20 g/d of 18:2n-6 to about 326 mg/d (1.03 mmole).

Influence of dietary arachidonic acid on metabolism in vivo of 8cis,11cis,14-eicosatrienoic acid in humans

This study investigated the influence of dietary arachidonic acid (20:4n-6) on delta 5 desaturation and incorporation of deuterium-labeled 8cis,11 cis, 14-eicosatrienoic acid (20:3n-6) into human plasma lipids. Adult male subjects (n = 4) were fed diets containing either 1.7 g/d (HI20:4 diet) or 0.21 g/d (LO20:4 diet) of arachidonic acid for 50 d and then dosed with a mixture containing ethyl esters of 20:3n-6[d4] and 18:1n-9[d2]. A series of blood samples was sequentially drawn over a 72-h period, and methyl esters of plasma total lipid, triacylglycerol, phospholipids, and cholesteryl ester were analyzed by gas chromatography-mass spectrometry. Based on the concentration of 20:3n6[d4] in total plasma lipid, the estimated conversion of 20:3n-6[d4] to 20:4n-6[d4] was 17.7 +/- 0.79% (HI20:4 diet) and 2.13 +/- 1.44% (LO20:4 diet). The concentrations of 20:4n-6[d4] in total plasma lipids from subjects fed the HI20:4 and LO20:4 diets were 2.10 +/- 0.6 and 0.29 +/- 0.2 mumole/mL plasma/mmole of 20:3n-6[d4] fed/kg of body weight. These data indicate that conversion of 20:3n-6[d4] to 20:4n-6[d4] was stimulated 7-8-fold by the HI20:4 diet. Phospholipid acyltransferase was 2.5-fold more selective for 20:3n-6[d4] than 18:1n-9[d2], and lecithin:cholesterol acyltransferase was 2-fold more selective for 18:1n-9[ds] than 20:3n-6[d4]. These differences in selectivity were not significantly influenced by diet. Absorption of ethyl 20:3n-6[d4] was about 33% less than ethyl 18:1n-9[d2]. The sum of the n-6 retroconversion products from 20:3n-6[d4] in total plasma lipids was about 2% of the total deuterated fatty acids. Neither absorption nor retroconversion appears to be influenced by diet.

Alternate pathways in the desaturation and chain elongation of linolenic acid, 18:3(n-3), in cultured glioma cells

Cultured C6 glioma cells rapidly incorporate and metabolize the essential fatty acids, 18:2(n-6) and 18:3(n-3), to 20- and 22-carbon polyunsaturated fatty acids. Using several deuterated fatty acid substrates we have obtained data that suggest alternate pathways, one possibly involving delta 8-desaturation, may exist in glioma cells for formation of 20:5(n-3) and 22:6(n-3) from 18:3(n-3). With 18:3(n-3)-6,6,7,7-d4 practically no 18:4(n-3)-6,7-d2 or 20:4(n-3)-8,9-d2 was detected whereas 20:3(n-3)-8,8,9,9-d4 accounted for 3.4% and delta 5,11,14,17-20:4-8,8,9,9-d4 for 21.1% of the total deuterated fatty acids recovered in phospholipids after a 16 h incubation; 20:5(n-3)-8,9-d2, 22:5(n-3)-10,11-d2, and 22:6(n-3)-10,11-d2 accounted for 42.4%, 13.2%, and 2.8% of deuterated acyl chains, respectively. When added exogneously, 20:3-8,8,9,9,-d4 was extensively converted to delta 5,11,14,17-20:4(n-3)-8,8,9,9-d4 (45%) and 20:5(n-3)-8,9-d2 (24%); a small amount (4%) of 18:3(n-3)-d4 also was detected. Both 20:4(n-3)-8,9-d2 and 18:4(n-3)-12,13,15,16-d4 were also converted to 20:5(n-3) and 22:6(n-3) with 8 and 0% of the respective original deuterated substrate remaining after 16 h. A possible pathway for 18:3(n-3) metabolism in glioma cells is described whereby an initial chain elongation step is followed by successive delta 5 and delta 8 desaturation reactions resulting in 20:5(n-3) formation and accounting for the ordered removal of deuterium atoms. Alternatively, extremely effective retroconversion may occur to chain shorten 20:3(n-3)-d4 to 18:3(n-3)-d4 followed by rapid conversion through the classical desaturation and chain elongation sequence.(ABSTRACT TRUNCATED AT 250 WORDS)