Effect of cyclodextrin diallyl maleate on methane production, ruminal fermentation and microbes in vitro and in vivo

Effects of β‐cyclodextrin diallyl maleate (CD‐M) on methane production, ruminal fermentation and digestibility were studied both in vitro and in vivo. In in vitro study, diluted ruminal fluid (30 mL) was incubated anaerobically at 38°C for 6 and 24 h with or without CD‐M using hay plus concentrate (1.5:1) as a substrate. The CD‐M was added at different concentrations (0, 1.25, 2.5, 5.0 and 7.5 g/L). The pH of the medium and numbers of protozoa were not affected by the addition of CD‐M. Total volatile fatty acids were increased and ammonia‐N was decreased, molar proportion of acetate was decreased and propionate was increased (P < 0.05) by CD‐M. Methane was inhibited (P < 0.05) by 14–76%. The effect of CD‐M on methane production and ruminal fermentation was further investigated in vivo using four Holstein steers in a cross‐over design. The steers were fed Sudangrass hay and concentrate mixture (1.5:1) with or without CD‐M (2% of feed dry matter) as a supplement. Ruminal proportion of acetate tended to decrease and that of propionate was increased (P < 0.05) 2 h after CD‐M dosing. Total viable counts, cellulolytic, sulfate reducing, acetogenic bacteria and protozoa were unaffected while methanogenic bacteria were decreased (P < 0.05) by CD‐M. The plasma concentration of glucose was increased, whereas that of urea‐N was decreased (P < 0.05). Methane was inhibited (P < 0.05) from 36.4 to 30.1 L/kg dry matter intake by the addition of CD‐M. Apparent digestibilities of dry matter and neutral detergent fiber were not affected while that of crude protein was increased (P < 0.05) in the medicated steers. These data suggested that dietary supplementation of CD‐M decreased methane production and improved nutrient use.     

Effects of cyclodextrin-iodopropane complex on methane production, ruminal fermentation and microbes, digestibility and blood metabolites in steers

The effects when adding cyclodextrin‐iodopropane complex (CD‐IP) to a diet, on ruminal fermentation and microbes, digestibility, blood metabolites and methane production, were evaluated using four Holstein steers in a cross‐over design. The steers were fed Sudangrass hay plus concentrate mixture at a ratio 1.5:1, and CD‐IP (1% of dry matter) was given twice daily by mixing with concentrate mixture. Rumen and blood samples were collected at 0, 2, and 5 h after morning dosing. Ruminal pH and numbers of protozoa were unaffected by CD‐IP treatment. Ruminal molar proportion of acetate was decreased (P < 0.05), and propionate was increased (P < 0.01) at 2 h after CD‐IP dosing. Proportion of butyrate was increased (P < 0.05) and ammonia‐N was decreased (P < 0.05) at 2 and 5 h after CD‐IP dosing. Adding CD‐IP had no effect on the feed intake and digestion of nutrients. Plasma glucose was increased and urea‐N was decreased (P < 0.05) at 2 and 5 h after CD‐IP dosing. Methane production was decreased (P < 0.05) by approximately 18% in the treatment steers. Numbers of methanogenic bacteria were decreased (P < 0.05), while total viable counts, cellulolytic, sulfate reducing and acetogenic bacteria were unaffected. The present results are the first to show that CD‐IP can partially inhibit in vivo ruminal methanogenesis without adverse effects on digestion of nutrients.     

Seasonal changes in digestibility, passage rate and rumen fermentation of alfalfa hay in sika deer (Cervus nippon) under restricted feeding

To investigate seasonal variations in the digestive functions of sika deer, five female sika deer were provided with an amount of alfalfa hay cubes equivalent to voluntary food intake during winter. We measured the rate at which the food passed through the digestive tract, digestibility and rumen fermentation during the summer (August), autumn (November), winter (February) and spring (May). Total mean retention time in the digestive tract during summer and autumn was numerically longer than that in winter and spring, but the difference did not reach significance. Organic matter and fiber were less digestible in summer and autumn than in winter and spring (P < 0.05), whereas the digestibility of the dry matter tended to vary with the seasons (P < 0.1). Ruminal pH values seasonally changed (P < 0.01), and were the lowest in autumn. The concentration of ruminal ammonia‐nitrogen differed significantly among the seasons (P < 0.05), increasing in winter and decreasing during spring and summer. The numbers of protozoa changed significantly among the seasons (P < 0.05), being higher in autumn than in winter and spring, and intermediate in summer. The concentration of total volatile fatty acids was not seasonally affected, but the molar percentages of propionic acid and butyric acid significantly changed according to season (P < 0.05 and P < 0.01, respectively), and the ratio of acetic to propionic acid tended to change with the seasons (P < 0.1). The results of this study suggested that the digestive functions in sika deer, fed a commercial diet at a restricted level, differed notably among the seasons and these variations might partially be due to environmental effects.     

Effect of presence of rumen protozoa on degradation of cell wall constituents in gastrointestinal tract of cattle

The cell wall constituents of feces from three faunated and three defaunated (without ruminal ciliate protozoa) cattle fed on a Sudangrass hay and concentrate mixture (8:5) were analyzed. There was little difference in digestibility of dry matter between the faunated and defaunated cattle. Analysis of the fecal sugar residues revealed that the digestibilities of arabinose and galactose, derived from pectic and hemicellulosic substances located within the compound middle lamella, were higher in the defaunated cattle than the faunated cattle (P < 0.05), whereas the digestibilities of glucose and xylose, derived mainly from cellulose and xylan, were unchanged by the removal of protozoa. The digestibility of lignin was not different between the faunated and defaunated cattle, but those of mannose and p‐coumaric acid were lower in the defaunated than in the faunated animals (P < 0.05). The ratio of primary cell wall to secondary cell wall in fecal plant materials was lower for the defaunated than for the faunated cattle. The results in this study suggested that the defaunation enhanced the microbial degradation of the thin cell walls, but depressed the degradation of developed cell walls.     

Fatty acid composition of ruminal bacteria and protozoa,and effect of defaunation on fatty acid profile in the rumen with special reference to conjugated linoleic acid in cattle

Objectives of this study were to compare fatty acid (FA) composition of ruminal bacterial (B) and protozoal (P) cells, and to investigate effect of protozoa on FA profile in the rumen of cattle. Three cows were used to prepare ruminal B and P cells. Four faunated and three defaunated cattle (half‐siblings) were used to study effect of protozoa on ruminal FA profile. Proportions of C16:0 and C18:0 in total fatty acids in B cells were 20.7% and 37.4%, whereas those in P cells were 33.4% and 11.6%, respectively. Proportions of trans‐vaccenic acid (VA) and cis‐9, trans‐11 conjugated linoleic acid (CLA) in B cells were 3.9% and 1.0%, and those in P cells were 5.5% and 1.6%, respectively, being higher in P cells. Proportions of C18:1, C18:2 and C18:3 in P cells were two to three times higher than in B cells. Proportions of unsaturated fatty acids, VA and CLA in B cells of faunated cattle were higher than those of defaunated. VA and CLA in the ruminal fluid of faunated were also 1.6 to 2.5 times higher than those of defaunated. This tendency was similar for cell‐free fraction of ruminal fluid. These results indicate that protozoa contribute greatly in VA and CLA production in the rumen.     

Effects of medium‐chain fatty acid‐cyclodextrin complexes on ruminal methane production in vitro

The purpose of the present study was to evaluate effects of medium‐chain fatty acid‐cyclodextrin (CD) complexes on ruminal methane and volatile fatty acid production, and protozoal activity in vitro. Medium‐chain fatty acid‐CDs used in this study were caprylic acid (C8)‐αCD or ‐βCD, capric acid (C10)‐αCD or ‐βCD, and lauric acid (C12)‐αCD or ‐βCD. A 60‐mL of diluted rumen fluid was incubated anaerobically at 38°C for 6 h with the addition of the complex (10–40 mg as fatty acid). Each of the fatty acid‐CDs reduced the number of protozoa, with the order C10 > C12 > C8, and βCD complexes were more effective than αCD complexes. Molar proportions of acetic acid remained unchanged with the addition of fatty acid‐CD, while that of propionic acid increased, being significant for C8‐αCD and βCD, and C10‐αCD and βCD (P < 0.05). Hydrogen production decreased by about 70% of control with the addition of 40 mg of C8 and C10‐CD, on the other hand, it tended to increase with the addition of C12‐CD in both αCD and βCD. Methane production decreased by about 20% with the addition of 40 mg of complexes, except for C10‐βCD, which significantly reduced methane production by about 60%. In conclusion, the addition of C8 or C10‐CD to ruminant diets may be effective in reducing methane production.     

Effect of propylene glycol and undegradable protein source on rumen fermentation, blood metabolism and milk production in lactating dairy cows

Eight lactating Holstein cows were divided into two groups ( n  = 4) and used in a double reversal trial with three periods of 14 days each, to evaluate diets containing propylene glycol (PG) and ruminally undegradable protein (RUP) blend on milk yield and composition, ruminal fermentation and blood metabolism. The control diet contained 20% chopped Sudangrass hay, 20% cubed alfalfa hay, 12% corn silage, and 48% of the respective concentrate mixtures (dry matter basis). The experimental diet (PG + RUP) partially replaced the concentrate mixture from the control diet with 1.4% PG and 2.1% RUP. Both diets contained about 16% crude protein and 71% total digestible nutrients. Dry matter intake was similar between the two diets. Daily production of milk, milk lactose and milk solids-not-fat increased by 9.0%, 11.3% and 9.3%, respectively ( P  < 0.1), for cows fed diets with PG + RUP; milk composition was unchanged. Although the concentration of ruminal total volatile fatty acids was unchanged, the proportion of propionic acid increased, and the proportion of acetic acid decreased with PG + RUP. The concentration of ruminal ammonia nitrogen and number of ciliate protozoa was not significantly affected by PG + RUP. The concentration of glucose in blood plasma increased, the concentration of urea nitrogen was unaffected, and the concentration of some essential free amino acids decreased with PG + RUP. It is suggested that these changes might be caused predominantly by PG, and the addition of PG may exert a favorable effect on milk production through increased metabolism.     

饲喂高亚油酸玉米对奶牛瘤胃发酵、产乳量和乳成分的影响

选用6头经产荷斯坦种乳牛分为对照和HLAC两组,以二乘反转法,研究了高亚油酸玉来(HLAC)对奶牛瘤胃发酵、产乳量和乳成分的影响。HLAC组用HLAC部分替换了对照组饲料中的普通玉米,两组日粮组成和营养成分基本相同。结果表明,HLAC的替换对瘤胃液氨氮浓度、挥发性脂肪酸浓度及其组成无显著影响(P>0.1),但纤毛虫总数显著增加(P>0.05)。两组牛干物采食量和乳量无显著差异,但HLAC组乳脂率有下降趋势(P>0.1)、乳脂肪中C18:2比例小幅提高、C18:1比例显著提高(P<0.05)、乳蛋白质率及其产量小幅增加、乳糖率和无脂固形物率及其产量显著提高(P<0.05)。以上结果显示:奶牛饲料中HLAC的使用可改善乳成分,并对瘤胃发酵产生一定影响。     

Cell wall degradation of tropical and temperate forage grasses measured by nylon bag and in vitro digestion techniques

Four tropical and four temperate grasses were subjected to nylon bag fiber degradation study with fistulated Holstein cattle as well as in vitro digestion with broad spectrum cellulase, and the degradability of cell wall carbohydrate and lignin for the respective forage grasses were determined. The degradability of neutral detergent fiber and acid detergent fiber for the same plant materials appeared to be similar, but that of acid detergent lignin was constantly lower. As for the plant materials used in the present study, Italian ryegrass, orchardgrass and guineagrass showed high degradability of fibers in nylon bag incubation, while setaria, cogongrass and wheat showed smaller degradability. In both nylon bag incubation and in vitro digestion experiments, the forage samples showing relatively lower degradability exhibited notably lower disappearance of xylose than that of glucose or arabinose. It was also observed that dry matter degradability correlated negatively with the initial content of esterified and/or etherified p‐coumaric acid. These results were assumed to be caused by the difference in resistance towards rumen microbial degradation due to the concentration of lignin‐carbohydrate complex.