Ruminal Volatile Fatty Acid Concentrations Research Articles

Effects of starch and protein sources on starch disappearance in the gastrointestinal tract of Hanwoo (Korean native) steers

Hanwoo (Korean native) steers (274.8 +/- 4.6 kg) with ruminal and duodenal cannulae were used in a 4 x 4 Latin square design experiment to examine the effects of dietary treatments on starch disappearance in the gastrointestinal tract. Dietary treatments consisted of concentrate that were based on ground corn with soybean meal (C-SBM), ground corn with corn gluten meal (C-CGM), ground barley with soybean meal (B-SBM) and ground barley with corn gluten meal (B-CGM). Although the intakes of starch and protein for steers fed experimental diets were different, it did not change ruminal pH and total volatile fatty acid concentrations. Average duodenal CP flow and quantity of CP apparently digested post-ruminally was higher (P = 0.001) for CGM-based diets than SBM-based diets. There were increases in quantity (P < 0.001) and percentage (P < 0.001) of corn starch digested post-ruminally compared to barley starch. Synchronized diets showed higher percentages (P = 0.03) of starch apparently digested post-ruminally than asynchronization. Hanwoo steers fed a corn-based diet with a large quantity of starch reaching the duodenum and fed C-CGM supplying great amounts of protein to the small intestine may have contributed to increased post-ruminal starch digestion.

Replacement of starch from corn with nonforage fiber from distillers grains and soyhulls in diets of lactating dairy cows

Forty Holstein cows were used in a completely randomized design with a 2-wk covariate period followed by a 6-wk experimental period to evaluate incremental substitution of nonforage fiber provided by dried distillers grains with solubles (DDGS) and soyhulls (SH) for starch provided by corn in the diet. Diets provided decreasing concentrations of starch: 29% starch with 0% DDGS; 26% starch with 7% DDGS; 23% starch with 14% DDGS; and 20% starch with 21% DDGS. Diets contained 27% corn silage, 22% alfalfa hay, and 51% concentrate mix and were formulated to be 17% crude protein, 4.7% fat, and 23% neutral detergent fiber from forage. Total neutral detergent fiber increased as DDGS and SH were included in the diet. Soyhulls were included in a linear fashion along with DDGS to replace soybean meal and expeller soybean meal, thereby maintaining a similar crude protein content across diets. Dry matter intake decreased linearly; consequently, feed efficiency tended to increase linearly as starch was replaced by nonforage fiber. There was no effect of diet on milk production or milk fat and protein percentage or yield. Milk fatty acid profiles were similar across diets. Other response variables, including 4% fat-corrected milk, total solids, and milk urea nitrogen, were unaffected by dietary treatments. Ruminal volatile fatty acid concentration did not differ between diets. Concentrations of blood glucose and β-hydroxybutyrate were similar across diets. Results from this research suggest that nonforage fiber from DDGS can partially substitute for starch from corn in dairy cow diets without affecting milk production and milk composition. Economic analysis of the diets showed that feeding DDGS and SH in substitution of corn was cost-effective. Results from this experiment indicate that DDGS and SH can replace corn as an energy source to decrease feed costs.

Increasing dietary sugar concentration may improve dry matter intake, ruminal fermentation, and productivity of dairy cows in the postpartum phase of the transition period

The current study was undertaken to investigate the effect of feeding diets varying in sugar concentration to postpartum transition cows on productivity, ruminal fermentation, and nutrient digestibility. We hypothesized that the high-sugar diet would increase dry matter intake and lactation performance. The secondary objective was to characterize changes in ruminal fermentation and nutrient digestibility over the first 4 wk of lactation. Fifty-two Holstein cows, including 28 primiparous and 24 multiparous cows, 10 of which were previously fitted with a ruminal cannula, were assigned to the experimental diets containing either high sugar (HS=8.4%) or low sugar (LS=4.7%) immediately after calving, based on their expected calving date. Data and samples were collected on d 5.2 ± 0.3, 12.2 ± 0.3, 19.2 ± 0.3, and 26.1 ± 0.3 relative to parturition for wk 1, 2, 3, and 4 respectively. Cows fed HS had increased dry matter intake compared with those fed LS (18.3. vs. 17.2 kg/d). Further, cows fed HS sorted for particles retained on the pan of the Penn State Particle Size Separator to a greater extent than cows fed LS. Feeding HS tended to increase nadir (5.62 vs. 5.42), mean (6.21 vs. 6.06), and maximum pH (6.83 vs. 6.65). The duration (h/d) and area (pH × min/d) that ruminal pH was below pH 5.8 were not affected by treatment. Ruminal volatile fatty acid concentration and molar proportions of individual volatile fatty acids were not affected by treatment. The digestibility of dry matter, organic matter, neutral detergent fiber, and starch were not affected by treatment, averaging 63.3, 65.2, 43.2, and 93.5%, respectively. Feeding HS decreased plasma glucose concentration compared with feeding LS (51.3 vs. 54.0 mg/dL), but concentration of plasma insulin was not affected by treatment, averaging 4.17μIU/mL. Cows fed HS had higher concentrations of plasma β-hydroxybutrate (17.5 vs. 10.5 mg/dL) and nonesterified fatty acids (344 vs. 280μEq/L). Milk yield and milk composition were not affected by treatment, but a tendency for increased milk fat yield was observed for cows fed HS compared with LS (1.44 vs. 1.35 kg/d). The results of the current study imply that replacing cracked corn grain with sucrose may improve dry matter intake, ruminal pH status, and lactation performance.

Effect of dietary forage to concentrate ratio on volatile fatty acid absorption and the expression of genes related to volatile fatty acid absorption and metabolism in ruminal tissue

The objective of the study was to investigate the fractional rate of volatile fatty acid (VFA) absorption and the expression of genes encoding for transporters and enzymes involved in the absorption and metabolism of VFA in ruminal tissue when cattle were fed high or low concentrate diets. Twelve ruminally cannulated Holstein cows were used in a randomized complete block design. The low concentrate (LC) and high concentrate (HC) diets contained 8 and 64% dietary concentrate (dry matter basis), respectively. Cows were fed their respective diet for at least 28 d, following which data and samples were collected over 6 d. Ruminal pH was measured continuously for 72h, and the in vivo VFA absorption and passage rates were measured using Co-EDTA and n-valeric acid as markers. Ruminal tissue was collected postslaughter from the ventral sac of the rumen, and gene expression was evaluated using quantitative real-time PCR. Dry matter intake was not affected by treatment, averaging 14.9 kg/d, but cows fed HC had lower mean ruminal pH (6.03 vs. 6.48), and a greater duration (376 vs. 10 min/d) that ruminal pH was <5.8. Ruminal VFA concentration was 24mM higher for cows fed HC compared with LC; however, the fractional rate of VFA absorption and passage from the rumen was not affected by dietary treatment, averaging 23.4 and 9.6%/h, respectively. The expression of genes encoding for enzymes involved in VFA activation and ketogenesis were not affected by treatment. Cows fed HC tended to have a relative abundance of pyruvate dehydrogenase lipoamide α 1 mRNA transcripts that was 1.4 times lower than that of cows fed LC, but other enzymes involved in pyruvate metabolism or regulation of the citric acid cycle were not affected. Collectively, these results suggest that the dietary forage to concentrate ratio does not affect the fractional rate of VFA absorption in vivo, but potentially alters energy metabolism in ruminal tissue.

Responses of Dairy Cows to Supplemental Highly Digestible Rumen Undegradable Protein and Rumen-protected Forms of Methionine

Metabolizable protein (MP) supply and amino acid balance in the intestine were manipulated through selection of highly digestible rumen-undegradable protein (RUP) sources and protected methionine (Met) supplementation. Four ruminally- cannulated, multiparous Holstein cows averaging 193±13 days in milk were used in a 4×4 Latin square design to assess N utilization and milk production responses to changes in RUP level, post-ruminal RUP digestibility and protected Met supplementation. Treatments were A) 14.0% crude protein (CP), 8.0% rumen degradable protein (RDP) and 6.0% RUP of low intestinal digestibility (HiRUP-LoDRUP); B) 14.1% CP, 8.1% RDP and 6.0% RUP of high intestinal digestibility (HiRUP-HiDRUP); C) 13.1% CP, 7.9% RDP and 5.2% RUP of high intestinal digestibility (LoRUP-HiDRUP), and D) 13.1% CP, 7.9% RDP and 5.2% RUP of high intestinal digestibility plus rumen escape sources of Met (LoRUP-HiDRUP+Met). Experimental diets were formulated to have similar concentrations of RDP, net energy of lactation (NEL), neutral detergent fiber (NDF), acid detergent fiber (ADF), calcium, phosphorus and ether extract using the NRC model (2001). Results showed that dry matter intake (DMI), production of milk fat and protein were similar among treatments. Milk production was similar for diet HiRUP-LoDRUP, HiRUP-HiDRUP and LoRUP-HiDRUP+Met, and significantly higher than diet LoRUP-HiDRUP. Milk fat and protein percentage were higher for cows receiving HiDRUP treatments, with the greatest increases in the diet LoRUP-HiDRUP+Met. There was no significant change in ruminal pH, NH3-N and volatile fatty acid (VFA) concentration among all treatments. Apparent digestibility of dry matter (DM), CP, NDF and ADF and estimated bacterial CP synthesis were similar for all treatments. Nitrogen intakes, blood and milk urea-N concentrations were significantly higher for cows receiving HiRUP diets. Urine volume and total urinary N excretion were significantly lowered by LoRUP diets. Lowering dietary RUP level while supplementing the highly digestible RUP source with rumen escape sources of Met resulted in similar milk production, maximal milk fat and protein concentration and maximum N efficiency, indicating that post-ruminal digestibility of RUP and amino acid balance in the small intestine

Increasing physically effective fiber content of dairy cow diets through forage proportion versus forage chop length: Chewing and ruminal pH

A study was conducted to evaluate whether the risk of acidosis in dairy cows can be lowered by increasing the physically effective fiber (peNDF) concentration of the diet, either through increased theoretical chop length of alfalfa silage or higher proportion of forage in the diet. The experiment was designed as a replicated 4×4 Latin square using 8 ruminally cannulated lactating dairy cows. Treatments were arranged in a 2×2 factorial design; 2 forage particle lengths (FPL) of alfalfa silage (short and long) were combined with low (35:65) and high (60:40) forage:concentrate (F:C) ratios [dry matter (DM) basis]. Dietary peNDF concentration (DM basis) was determined from the sum of the proportion of dietary DM retained either on the 2 sieves (8 and 19mm) or on the 3 sieves (1.18, 8, and 19mm) of the Penn State Particle Separator multiplied by the neutral detergent fiber concentration of the diet. The dietary peNDF concentrations were altered by changing the F:C or the FPL, and ranged from 10.7 to 17.5% using 2 sieves, or from 23.1 to 28.2% using 3 sieves. Intake of peNDF was increased by increasing FPL but not by increasing F:C ratio because of the reduction of DM intake at the higher F:C ratio. Chewing activity, including number of chews and chewing time, increased with increasing F:C ratio or FPL. Mean ruminal pH was elevated by 0.4 and 0.2 units with increasing F:C ratio and FPL, respectively. Lowering the F:C ratio decreased the duration that ruminal pH was below 5.8 (1.2 vs. 8 h/d). Increased F:C ratio or FPL reduced ruminal volatile fatty acids concentration from 137 to 122 or from 133 to 126mM, respectively, whereas acetate:propionate ratio was increased from 2.55 to 3.46 with increasing F:C ratio. Dietary peNDF concentration measured using 2 sieves was correlated to chewing time (r=0.57) and mean ruminal pH (r=0.75), whereas dietary peNDF concentration measured using 3 sieves was correlated to mean ruminal pH (r=0.83) and negatively correlated to the time that pH was below 5.8 (r=−0.78). This study shows that the risk of ruminal acidosis is high for cows fed a low F:C diet. Increasing the proportion of forage in the diet helps prevent ruminal acidosis through increased chewing time, a change in meal patterns, and decreased ruminal acid production. Increasing FPL elevates ruminal pH, but in low forage diets, increased FPL does not alleviate subacute acidosis because the fermentability of the diet is high and changes in chewing activity are marginal.

Effects of feeding increased amounts of wet corn gluten feed on dairy cow metabolism and milk production (2009)

An experiment was conducted to evaluate the effects of feeding increasing dietary amounts of wet corn gluten feed (WCGF). Eight lactating Holstein cows were housed in a tie-stall facility and fed 1 of 4 diets containing 0, 11, 23, or 34% WCGF on a dry matter basis. To maintain similar nutrient concentrations, alfalfa hay, corn silage, corn grain, soybean meal, expeller soybean meal, and mineral supplements varied across diets. Feed intake, milk production, body weight, and body condition score were monitored, and effects of WCGF inclusion rate were assessed. Increasing the level of WCGF in the diet led to increased feed intake, milk production, and body condition. Concentrations of milk components did not differ among treatments; therefore, yield of energy-corrected milk and solids-corrected milk increased as well. In contrast, increasing dietary WCGF decreased efficiency of production and also decreased ruminal pH, possibly because treatments with greater proportions of WCGF had a decreased mean particle size. As expected, the decreased ruminal pH coincided with changes in ruminal volatile fatty acid concentrations. Furthermore, the rate of fiber digestion after 24 hours decreased when more WCGF was incorporated into diets. Results indicate that adding WCGF to dairy rations can increase energy-corrected milk yield, and this increase seems to be driven, at least in part, by an increase in feed intake.

The Effects of Live Yeast Culture (Saccharomyces cerevisiae) on Rumen Fermentation and Nutrient Degradability in Yearling Lambs

Summary This study was carried out in two experiments. Experiment 1 was conducted with six ruminally-cannulated one-year old Kangal Akkaraman male lambs, using a crossover design with 2 periods to determine the effects of live yeast culture supplementation on rumen fermentation. Yearlings were either supplemented with 4 g/d of Saccharomyces cerevisiae (BeneSacc, 4x10 9 CFU/g) or not supplemented (control). Animals were penned individually, and were fed a diet composed of 25% forage and 75% concentrate for sixteen days. Rumen fluid was sampled on day 16, 0 h (before feeding), 3 h and 6 h after feeding. Rumen pH, the numbers of protozoa, ammonia-N and volatile fatty acids (VFA) were determined in samples. Molar proportions of acetate were decreased, and propionate was increased with supplementation of live yeast culture. No differences were observed for ruminal pH, protozoa population, total VFA and ammonia-N concentrations, between treatments. In Experiment 2, in situ nutrient degradability of barley grain, corn dried distillers grains with solubles (DDGS) and wheat straw were determined. Live yeast culture supplementation did not affect dry matter (DM) degradability of barley, DDGS or straw, crude protein (CP) degradability of DDGS, nor neutral detergent fiber (NDF) degradability of straw. But, it reduced the potential degradability of DDGS in rumen..

Starch Source Evaluation in Calf Starter: II. Ruminal Parameters, Rumen Development, Nutrient Digestibilities, and Nitrogen Utilization in Holstein Calves

Ruminal parameters, rumen development, nutrient digestibilities, and N utilization were estimated in Holstein calves fed starch from different sources. Ground corn, ground barley, ground wheat, and crimped oats were used to formulate 4 isostarch (25% of starter dry matter) pelleted diets. These diets were randomly allocated to calves (16 calves per treatment, 8 female and 8 male) and fed ad libitum along with mixed grass hay throughout the experiment. Ruminal contents and blood were sampled at d 35, 50, and 70 of age to estimate ruminal parameters and plasma β-hydroxybutyrate, respectively. At d 70, twenty-four male calves (6/treatment) were randomly selected, euthanized, and forestomach weight, papillae length (PL), papillae width (PW), rumen wall thickness (RWT), and papillae concentration were measured. At d 63, twenty-four female calves (6/treatment) were randomly selected and moved to metabolism stalls to estimate total tract apparent nutrient digestibilities and N utilization. Female calves were given 2 wk for adaptation to experimental facilities and then total collections of feces and urine were made from d 77 to 84 of age. Ruminal pH at d 35 of age was higher in calves fed corn and oat diets than in those fed barley and wheat diets. Ruminal pH at d 50 and 70 of age was the lowest in calves on barley diets followed by those on oat and wheat diets and then by those on the corn diet. Ruminal total volatile fatty acid concentrations at d 35 of age were greatest in calves fed corn or wheat diets followed by those fed barley and oat diets. Calves on corn and wheat diets maintained greater ruminal volatile fatty acids concentrations at d 50 and 70 of age. Ruminal ammonia, acetate, propionate, butyrate, and blood β-hydroxybutyrate concentrations were also greater in calves on the corn and wheat diets. Full and empty weights of forestomach, PL, PW, RWT, and papillae concentrations were greater in calves on corn and wheat diets. Daily average intake of nutrients (dry matter, crude protein, neutral detergent fiber, starch, Ca, and P) was greater in calves fed corn and wheat diets than in those fed barley and oat diets. Starch source did not influence the total tract apparent digestibilities of nutrients in calves. Daily N retention (g/d) was greatest on the corn diet followed by the wheat diet and then the barley and oat diets. In conclusion, calves on a corn diet have greater ruminal capacity to accommodate feed bulk. More physically and metabolically functional rumens in calves on corn and wheat diets probably resulted in greater feed consumption and N retention.

Effect of Incremental Urea Supplementation of a Conventional Corn Silage-Based Diet on Ruminal Ammonia Concentration and Synthesis of Microbial Protein

One primiparous and 3 multiparous lactating Holstein cows fitted with ruminal and duodenal cannulas were used in a 4×4 Latin square design to determine the efficacy of adding urea to a corn silage-based diet on ruminal fermentation and microbial protein synthesis. Dietary treatments were 0, 0.3, 0.6, and 0.9% urea in diet dry matter (DM); urea was manually top dressed and incorporated into the ration. The basal diet contained (DM basis) 52% forage (with 61% of forage provided as corn silage) and 48% concentrate ingredients. The basal diet was formulated to meet National Research Council (NRC, 2001) requirements for energy and all nutrients except rumen-degradable protein (RDP) and metabolizable protein. Experimental periods lasted 14 d with the first 9 d for adaptation. The basal diet, without urea addition, contained 9.2% RDP in DM and had a predicted RDP balance of −167g/d (NRC, 2001). There were no effects of dietary treatment on ruminal true digestibility of organic matter or ruminal apparent digestibility of neutral detergent fiber and acid detergent fiber. Total ruminal volatile fatty acid concentrations increased linearly with increasing urea level. Feeding increasing amounts of urea quadratically increased rumen ammonia N concentrations (9.0, 11.9, 12.8, and 17.4mg/dL at 0, 0.3, 0.6, and 0.9% urea supplementation, respectively), passage of microbial N, and microbial N in duodenal digesta as a percentage of nonammonia N. The results of this study indicate that there were some positive effects of adding urea to the described lactating dairy cow diet, and that microbial protein synthesis was maximized at an average ruminal ammonia N concentration of 12.8mg/dL when urea was added at 0.6% in diet DM.

Establishment and Development of Ruminal Hydrogenotrophs in Methanogen-Free Lambs

The aim of this work was to determine whether reductive acetogenesis can provide an alternative to methanogenesis in the rumen. Gnotobiotic lambs were inoculated with a functional rumen microbiota lacking methanogens and reared to maturity on a fibrous diet. Lambs with a methanogen-free rumen grew well, and the feed intake and ruminal volatile fatty acid concentrations for lambs lacking ruminal methanogens were lower but not markedly dissimilar from those for conventional lambs reared on the same diet. A high population density (10(7) to 10(8) cells g(-1)) of ruminal acetogens slowly developed in methanogen-free lambs. Sulfate- and fumarate-reducing bacteria were present, but their population densities were highly variable. In methanogen-free lambs, the hydrogen capture from fermentation was low (28 to 46%) in comparison with that in lambs containing ruminal methanogens (>90%). Reductive acetogenesis was not a significant part of ruminal fermentation in conventional lambs but contributed 21 to 25% to the fermentation in methanogen-free meroxenic animals. Ruminal H(2) utilization was lower in lambs lacking ruminal methanogens, but when a methanogen-free lamb was inoculated with a methanogen, the ruminal H(2) utilization was similar to that in conventional lambs. H(2) utilization in lambs containing a normal ruminal microflora was age dependent and increased with the animal age. The animal age effect was less marked in lambs lacking ruminal methanogens. Addition of fumarate to rumen contents from methanogen-free lambs increased H(2) utilization. These findings provide the first evidence from animal studies that reductive acetogens can sustain a functional rumen and replace methanogens as a sink for H(2) in the rumen.

랜드레이스, 요크셔, 듀록 및 교잡종에 대한 도체 및 육질특성

본 실험은 alcohol 사료 처리에 따른 in vitro 발효 pattern의 변화를 검토하여 alcohol 사료 처리가 반추위내 발효 pattern에 미치는 영향을 규명코자 실시하였다. 시험구 처리는 배합사료를 첨가하는 대조구(control), 배합사료와 1, 3 및 5%의 alcohol 사료(Alcoholic feed; AF)를 첨가하는 처리구를 각각 AF-1구, AF-3구 및 AF-5구로 나누어 실시하였다. 배양 12시간 동안 ammonia 농도는 AF-1, AF-5구에서 대조구에 비해 낮았다(p<0.05). 배양액의 alcohol 농도는 alcohol 첨가 수준이 증가할수록 높았다(p<0.05). 배양 12시간에 TVFA 농도는 AF-1, AF-3 및 AF-5에서 대조구에 비해 현저히 높았다(p<0.05). 배양 8～12시간 사이에 acetate 비율은 대조구에서 빠른 속도로 감소하였으며, AF-1, AF-3 및 AF-5구에서는 일정한 수준을 유지하는 것으로 나타났다. Propionate 비율은 배양 8～12시간 사이에 AF-1, AF-3 및 AF-5에 비해 대조구에서 빠른 속도로 증가하였다(p<0.05). Butyrate 및 valerate 비율은 AF-1, AF-3 및 AF-5에서 대조구에 비해 높았다(p<0.05). Caproate 비율은 배양 8시간에 AF-1구, AF-3구 및 AF-5구에서 각각 0.05, 0.58 및 0.47M%로 나타났으나, 대조구에서는 검출되지 않았다. 본 실험의 결과에서 alcohol 사료의 처리는 in vitro 반추위액의 ammonia, alcohol 및 휘발성지방산 농도와 pH에 긍정적인 영향을 미치는 것으로 판단된다. 또한 본 실험의 결과에서는 5%의 alcohol 첨가 수준이 여타 alcohol 첨가 수준에 비해 반추위 발효에 보다 효과적인 것으로 사료된다. In this study, changes of ammonia, alcohol and volatile fatty acid(VFA) concentrations or pH in in vitro ruminal fluid were studied to determine the effects of alcoholic feeds on in vitro ruminal fermentation characteristics. To formulate the alcoholic feeds, alcohol was added to commercial formulated feed at the levels of 1, 3, and 5 %. Experiments were done with four treatment groups, control(commercial feed), AF-1(commercial feed+1% alcohol), AF-3(commercial feed+3% alcohol), and AF-5(commercial feed+5% alcohol). Ammonia concentrations of AF-1 and AF-5 were significantly lower than that of control for the 12h incubation(p<0.05). Ruminal alcohol concentration was increased with the addition level of alcohol increased(p<0.05). TVFA concentrations of AF-1, AF-3 and AF-5 were significantly higher than those of control at 12h(p<0.05). Significant decrease of molar percentage of acetate was observed in control from 8 to 12h incubation, but molar percentage of acetate for AF-1, AF-3 and AF-5 was constant. Molar percentage of propionate was increased in control compared with AF-1, AF-3 and AF-5 from 8 to 12h incubation(p<0.05). Molar percentages of butyrate and valerate were higher in AF-1, AF-3 and AF-5 than in control(p<0.05). Molar percentage of caproate for AF-1, AF-3 and AF-5 was 0.05, 0.58 and 0.47M% at 8h, respectively, but that was not detected for control. Present results may indicate that the alcoholic feeds show positive effects on in vitro ruminal ammonia, alcohol and VFA concentrations or pH. Furthermore, the results of this study implies that the addition level of 5% could be more effective to ruminal fermentation than other addition levels.

Alcohol 사료가 In vitro 반추위내 pH, Ammonia, Alcohol 및 Volatile Fatty Acids 농도에 미치는 영향

본 실험은 alcohol 사료 처리에 따른 in vitro 발효 pattern의 변화를 검토하여 alcohol 사료 처리가 반추위내 발효 pattern에 미치는 영향을 규명코자 실시하였다. 시험구 처리는 배합사료를 첨가하는 대조구(control), 배합사료와 1, 3 및 5%의 alcohol 사료(Alcoholic feed; AF)를 첨가하는 처리구를 각각 AF-1구, AF-3구 및 AF-5구로 나누어 실시하였다. 배양 12시간 동안 ammonia 농도는 AF-1, AF-5구에서 대조구에 비해 낮았다(p<0.05). 배양액의 alcohol 농도는 alcohol 첨가 수준이 증가할수록 높았다(p<0.05). 배양 12시간에 TVFA 농도는 AF-1, AF-3 및 AF-5에서 대조구에 비해 현저히 높았다(p<0.05). 배양 8～12시간 사이에 acetate 비율은 대조구에서 빠른 속도로 감소하였으며, AF-1, AF-3 및 AF-5구에서는 일정한 수준을 유지하는 것으로 나타났다. Propionate 비율은 배양 8～12시간 사이에 AF-1, AF-3 및 AF-5에 비해 대조구에서 빠른 속도로 증가하였다(p<0.05). Butyrate 및 valerate 비율은 AF-1, AF-3 및 AF-5에서 대조구에 비해 높았다(p<0.05). Caproate 비율은 배양 8시간에 AF-1구, AF-3구 및 AF-5구에서 각각 0.05, 0.58 및 0.47M%로 나타났으나, 대조구에서는 검출되지 않았다. 본 실험의 결과에서 alcohol 사료의 처리는 in vitro 반추위액의 ammonia, alcohol 및 휘발성지방산 농도와 pH에 긍정적인 영향을 미치는 것으로 판단된다. 또한 본 실험의 결과에서는 5%의 alcohol 첨가 수준이 여타 alcohol 첨가 수준에 비해 반추위 발효에 보다 효과적인 것으로 사료된다. In this study, changes of ammonia, alcohol and volatile fatty acid(VFA) concentrations or pH in in vitro ruminal fluid were studied to determine the effects of alcoholic feeds on in vitro ruminal fermentation characteristics. To formulate the alcoholic feeds, alcohol was added to commercial formulated feed at the levels of 1, 3, and 5 %. Experiments were done with four treatment groups, control(commercial feed), AF-1(commercial feed+1% alcohol), AF-3(commercial feed+3% alcohol), and AF-5(commercial feed+5% alcohol). Ammonia concentrations of AF-1 and AF-5 were significantly lower than that of control for the 12h incubation(p<0.05). Ruminal alcohol concentration was increased with the addition level of alcohol increased(p<0.05). TVFA concentrations of AF-1, AF-3 and AF-5 were significantly higher than those of control at 12h(p<0.05). Significant decrease of molar percentage of acetate was observed in control from 8 to 12h incubation, but molar percentage of acetate for AF-1, AF-3 and AF-5 was constant. Molar percentage of propionate was increased in control compared with AF-1, AF-3 and AF-5 from 8 to 12h incubation(p<0.05). Molar percentages of butyrate and valerate were higher in AF-1, AF-3 and AF-5 than in control(p<0.05). Molar percentage of caproate for AF-1, AF-3 and AF-5 was 0.05, 0.58 and 0.47M% at 8h, respectively, but that was not detected for control. Present results may indicate that the alcoholic feeds show positive effects on in vitro ruminal ammonia, alcohol and VFA concentrations or pH. Furthermore, the results of this study implies that the addition level of 5% could be more effective to ruminal fermentation than other addition levels.

Effects of synchronizing starch and protein degradation in rumen on fermentation, nutrient utilization and total tract digestibility in sheep

The objective of this experiment was to investigate the effects of synchronizing the dietary starch and crude protein (CP) degradation in the rumen on nutrient utilization, fermentation, and total tract digestibility in sheep. The four diets were formulated with different rates of starch and CP release in the rumen but with similar metabolic energy, starch, and CP. The diets were slowly degradable starch, slowly degradable protein; slowly degradable starch, rapidly degradable protein; rapidly degradable starch, rapidly degradable protein; and rapidly degradable starch, slowly degradable protein. The diets were fed to four cannulated sheep ad libitum in two equal portions, using a 4x4 Latin square design.Dry matter intake (DM) was not influenced by either the rate of starch or protein degradation. There was no significant effect of dietary treatment on the digestibility of DM, organic matter, starch, CP, neutral detergent fiber or acid detergent fiber in the rumen and total tract. Ruminal pH was greater for sheep fed slowly degradable starch diets than rapidly degradable starch (P< 0.05). Ruminal total volatile fatty acid concentrations were not affected by treatments but the molar proportions of propionic acid were greater for sheep fed rapidly degradable starch diets than slowly degradable starch diets (P< 0.05). The ratios of acetic acid (A) to propionic acid (P) were higher for sheep fed slowly degradable starch diets than rapidly degradable starch diets (P< 0.05). Ruminal ammonia-N concentrations were not affected from the degradability characteristics of protein. Rumen pH and A:P were higher in diets containing slowly degradable starch than in diets rapidly degradable starch. Propionic acid was higher in diets containing rapidly degradable starch than in diets containing slowly degradable starch. Rumen fermentation and utilization of nutrients in the rumen affected starch degradability more than protein degradability. Synchronizing starch and protein degradation in rumen had no effect on the intake, digestibility of nutrients in sheep.

Wet Corn Gluten Feed Fed Fresh or Stored and Supplemented with Rumen Undegradable Protein in the Diets of Lactating Dairy Cows

The main objective was to evaluate replacing fresh with long-term stored wet corn gluten feed (WCGF) in lactating cow diets and to evaluate added levels of rumen undegradable protein (RUP) to diets with WCGF. Twenty-four multiparous Holstein cows averaging 558 ± 45kg of BW and 57 ± 35 d in lactation were stratified by age, days in milk, and milk yield and assigned to one of four treatments: 1) fresh WCGF, 5.4% RUP DM; 2) stored WCGF, 5.4% RUP DM; 3) stored WCGF, 6.3% RUP DM, and 4) stored WCGF, 7.2% RUP DM. Total mixed rations containing 19% dietary DM as WCGF were formulated to be isonitrogenous (17.2% CP) and isoenergetic (7.20MJ NEl/kg of DM). The substitution of fresh WCGF as stored WCGF did not affect (P>0.10) milk yield or composition. Supplementing stored WCGF with RUP did not alter (P>0.10) actual or adjusted milk yield, but milk casein (P=0.03), fat (P=0.04), and total solids (P=0.03) increased in a linear fashion with increasing RUP supplementation. Ruminal ammonia concentration increased linearly (P<0.05), and total ruminal volatile fatty acid concentrations were similar among treatments; acetate increased (P<0.05), and butyrate decreased (P<0.05) with increasing levels of supplemental RUP. The WCGF may be stored for extended periods in an oxygen-limiting environment without reducing palatability or nutrient availability. Adding RUP may increase milk components when used in diets balanced for the nutrient demands of high producing dairy cows.

Effect of Different Dietary Geometric Mean Particle Length and Particle Size Distribution of Oat Silage on Feeding Behavior and Productive Performance of Dairy Cattle

Twenty lactating Holstein cows (5 primiparous and 15 multiparous) were used in a 5×5 Latin Square design, with 5 treatments and 3 periods of 21 d each. Diets contained 25% corn silage, 25% oat silage, and 50% concentrate (dry matter basis). The 5 treatments tested in the experiment were long oat silage (LOS), medium oat silage (MOS), fine from long oat silage (FLOS), fine from medium oat silage (FMOS), and half LOS plus half FLOS (LFLOS). The geometric mean particle length (GMPL) of the diets was 6.68, 5.19, 4.46, 4.35, and 5.39mm for LOS, MOS, FLOS, FMOS, and LFLOS, respectively. The LFLOS was designed to provide dietary GMPL similar to MOS, but with a more bimodal particle size distribution (PSD). Linear and quadratic effects of GMPL were tested, based on the mean GMPL of the feed actually consumed (cGMPL). Contrasts were used to test for the effect of different PSD (MOS vs. LFLOS) and to test for differences between FMOS and FLOS, which would indicate unequal fermentations in the MOS and LOS silos. No differences were detected between FMOS and FLOS in most of the variables measured. Increasing cGMPL linearly decreased dry matter intake, milk production, and milk protein percentage and yield without affecting milk fat percentage, milk fat yield, ruminal pH, and ruminal volatile fatty acid concentration. Although cows fed diets with increasing cGMPL spent more time eating and chewing per day and per kilogram of dry matter intake, there was no effect of cGMPL on rumen pH. Feeding medium oat silage increased milk fat percentage and yield compared with feeding a mixture of long and fine oat silage.

Effects of a Monensin Controlled-Release Capsule or Premix on Attenuation of Subacute Ruminal Acidosis in Dairy Cows

The effects of monensin, administered either as a controlled release capsule (CRC) or a premix, on attenuating grain-induced subacute ruminal acidosis (SARA) and on ruminal fermentation characteristics in Holstein cows receiving a total mixed ration were investigated in two experiments. In both experiments, six multiparous, rumen-fistulated Holstein cows were used in a two-treatment, two-period crossover design with 6-wk periods. In Experiment 1, treatments were either a monensin CRC or a placebo CRC. In Experiment 2, treatments were either a monensin premix or a placebo premix. In both experiments, at the beginning of wk 4 SARA was induced in experimental cows for a 10-d period with a grain challenge model, and ruminal pH was measured continuously using indwelling pH probes. The administration of monensin either as a CRC or a premix had no effect on ruminal pH characteristics. Neither monensin CRC nor premix had an effect on ruminal volatile fatty acid concentrations, but reduced the acetate:propionate ratio. Monensin premix-treated cows were observed to have increased milk yield, largely as a result of a higher dry matter intake in monensin-treated cows compared to control cows. Milk fat content and yield were lower in monensin-treated cows compared to placebo-treated cows during SARA. In conclusion, there is no evidence that monensin was efficacious in raising ruminal pH during SARA under the conditions employed in this study.

Effects of a non-starch polysaccharidase enzyme preparation from Thermomyces lanuginosus on energy and protein metabolism and milk yield of dairy cattle

Non-starch polysaccharides (NSPs) form an integral part of the cell walls in plants and represent considerable available energy when degraded into absorbable mono-, di-, tri- and oligosaccharides. The ruminal microflora hydrolyses a good part of NSPs, however, recently there have been attempts to enhance the rate of utilisation by using external polysaccharidase enzymes. In the present study the effects of an enzyme preparation (Rumino-Zyme) high in xylanase activity were studied on ruminal volatile fatty acid (VFA) concentration, parameters of energy and protein metabolism, milk yield, feed conversion ratio (FCR) and body condition score of high-yielding dairy cows. A lignolytic enzyme preparation produced by the thermophilic fungus Thermomyces lanuginosus was applied in the present experiment and fed to dairy cows at 34 g/day dosage in the period between calving and the 110th day of lactation. This preparation increased VFA concentration in the rumen from about 32 days after calving and onward. Increased VFA concentration was followed by an about 5 to 10% increase in milk production and an almost 0.1% increase in butterfat production. Increased VFA concentration produced more balanced energy metabolism in the experimental cows as indicated by the lower incidence rate of hyperketonaemia, and lower acetoacetic acid and non-esterified fatty acid (NEFA) concentration in the blood of the experimental cows. Aspartate aminotransferase (AST) activity was tendentiously higher in the control group and the proportion of cows that had AST activity higher than 100 U/l was also higher in the control group. Both control and experimental cows showed balanced protein and acid-base metabolism throughout the experiment. Enhanced VFA concentration contributed to an improvement in energy balance in the experimental cows with a resultant improvement of feed intake and feed utilisation. Due to the more balanced energy metabolism postparturient body condition loss of the treated cows was reduced.

Effects of barley silage of different theoretical cut length on digestion kinetics in ruminants

Two studies were conducted to determine the effects of two theoretical lengths of cut (TLC) (short = 4.7 mm and long = 18.8 mm) on the feeding value of barley silage to steers fed an all-forage diet. In the first study, six steers were used to determine intake of dry matter, total tract digestibility of dry matter (DMD), neutral detergent fiber (NDFD), and acid detergent fiber (ADFD) in a replicated switchback design. In the second study, six steers equipped with rumen cannulas were used to determine the effects of barley silage particle size on ruminal kinetic and fermentation parameters. Feeding short barley silage to steers increased (P &lt; 0.05) dry matter intake (DMI), DMD, NDFD, and ADFD compared with feeding long barley silage. The results of the second study showed that reducing barley silage particle size decreased (P &lt; 0.05) ruminal retention time and increased (P &lt; 0.05) passage rate of particulate matter. Ruminal pH was lower (P &lt; 0.05) at 1000, 1200, 1800, 2000, and 2200 h for steers fed the short barley silage compared with those fed the long barley silage. However, the effects of barley silage particle size on ruminal ammonia nitrogen and volatile fatty acid (VFA) concentrations were minimal. Eating rate was similar in both dietary treatments (average 40.3 g min-1). However, steers fed the long silage produced more (P &lt; 0.05) saliva per kg DMI compared with those fed the short barley silage diets. It was concluded that reducing TLC of barley silage increased feed intake and improved total tract utilization of cell wall components by steers. Results of the metabolism study also showed changes in fermentation parameters, but no adverse physiological changes were noted when cattle were fed all forage diets. Key words: Barley silage, particle size, fermentation patterns

The chemical composition of Phyllanthus discoideus and its effect on the ruminal ammonia and volatile fatty acid concentration when fed to west african dwarf sheep

The feeding value of Phyllanthus discoideus (also called Margaritaria discoidea) leaves was evaluated using eight two‐year‐old West African Dwarf sheep fed natural grass hay. Four of the animals were fistulated ruminally and used for ammonia and volatile fatty acid determination in the fluid. Dried leaves of Phyllanthus discoideus were offered at two levels (25% and 50% of DMI, diets D25% and D50%, respectively) as supplements to the basal hay diet. The CP content of the control, D25% and D50% diets were 11.5, 12.6 and 13.6%, respectively, and their digestible energy amounted to 58.2, 61.1 and 56.9%, respectively. Rumen liquor was sampled one hour before and one, three and five hours after the morning feeding. Sheep fed the control diet had a higher ruminai ammonia concentration than those fed diet D25%. Similarly, ruminai ammonia concentration was higher in sheep fed the control diet than those fed the diet D50%. Five hours after feeding the ruminai ammonia concentration was significantly lower than one hour after feeding. The VFA concentrations in rumen fluid of sheep fed the control diet was inferior to those fed diets D25% and D50%. Sheep fed diet D50% showed significantly higher VFA concentrations than those fed diet D25%. Digestibility of organic matter and digestible energy did not show any significant difference. However, a marginal increase in organic matter digestibility of 3.5% was observed in diet D25% compared with the control diet. There was no significant difference in the N‐digestibility in sheep fed the control, D25% and D50% diets. Nevertheless, a marginal improvement in N‐digestibility (1.5%) and N‐retention (2.7%) was observed with the highest level of Phyllanthus discoideus (D50%). In conclusion, Phyllanthus discoideus appears as a particularly valuable feedstuff because it contains low levels of condensed tannins (12.8 g/kg), high CP content (156 g/kg) and a relatively high GE content (19.3 kJ/gDM). Although the improvement in N‐digestibility and N‐retention were only marginal the feeding of Phyllanthus discoideus could be justified under extreme shortage of feed resources during dry season. It should also be mentioned that a much more pronounced effect by supplementation with Phyllanthus discoideus could be expected when poor quality grass hay prevalent in West Africa during the dry season is fed. Phyllanthus discoideus could serve as a supplement to poor quality grass at 25% to 50% of supplementation.