Ruminal Organic Matter Digestion Research Articles

Effects of monensin and virginiamycin supplementation in finishing diets with distiller dried grains plus solubles on growth performance and digestive function of steers

Two trials were conducted to evaluate the influence of virginiamycin (26 mg/kg) and monensin (34 mg/kg) supplementation of a steam-flaked corn-based finishing diet containing 15% distiller dried grains plus solubles (DDGS) on growth performance and digestive function. In Trial 1, 135 steers (257 ± 21 kg) were used to evaluate treatment effects on 145-d growth performance. There were no treatment effects (P > 0.20) on dry matter intake (DMI). Antibiotic supplementation tended to increase average daily gain (ADG; 7%, P = 0.07); increased gain efficiency (11%, P < 0.01) and estimated dietary net energy (NE; 10%, P < 0.01). Carcass marbling score was greater (12%, P = 0.04) for virginiamycin vs. monensin. In Trial 2, three Holstein steers (300 ± 7 kg) were used in a 3 × 3 Latin square to evaluate treatment effects on digestion. Both monensin and virginiamycin depressed ruminal digestion of organic matter (OM; 6%, P < 0.01) and feed nitrogen (N, 15%, P = 0.03) and microbial protein synthesis (15%, P = 0.03). There were no treatment effects of total tract OM and N digestion. Antibiotic supplementation increased (2.3%, P = 0.02) ruminal pH, associated with decreased (7%, P = 0.04) ruminal volatile fatty acids (VFA) concentrations. It is concluded that monensin and virginiamycin supplementation of growing-finishing diets for feedlot cattle may enhance daily weight gain, gain efficiency and dietary energetics. These effects are associated with a shift towards great intestinal OM digestion and decreased ruminal degradation of feed N and microbial protein synthesis.

Non-destructive foliar chlorophyll measurement has the potential to predict crude protein concentration and in vitro ruminal organic matter digestibility in Bracharia decumbens herbage

Quick and accurate estimation of crude protein (CP) concentration and in vitro ruminal organic matter digestibility (IVOMD) of tropical pastures is critical to determine possible nutrient deficits prior to herbage utilization. We, therefore, investigated the potential of a non-destructive hand-held chlorophyll gun (FieldScout CM 1000 NDVI Meter) to predict lignin (sa), acid detergent fiber (ADF), CP concentration and IVOMD of growing Bracharia decumbens Cv. Basilik herbage. The average of five (5) foliar chlorophyll index measurements obtained by a “point and shoot” action from an approximate 40–45° vertical angle prior to harvesting from each sampling unit was recorded. After chlorophyll measurements, herbage samples were cut according to a stratified random sampling design from four differently managed B. decumbens Cv. Basilik pastures to leave an 11cm stubble height. Herbage sampling was synchronized with existing grazing patterns used at the study sites. The respective pastures were sampled at 14 (Brac-14), 28 (Brac-28), 11 (Brac-11) and 13 (Brac-13) days post-grazing. Relationships between chlorophyll indices (CI), pasture CP concentration and IVOMD were best described by simple linear and polynomial models, respectively. Correlation coefficients (r2) between CI and CP and IVOMD ranged from 0.70 to 0.95 and 0.69–0.85, respectively. Chlorophyll index gave the best estimates for CP concentration and IVOMD in Brac-14 and Brac-13 where CCC and R2 was high, and rMSPE and model related errors were very low. Chlorophyll gun indices accounted for 68–90% and 64–78% variance of CP and IVOMD (P<0.05), respectively, in Brac-14 and Brac-13 herbage. Prediction models for lignin (sa) and ADF were inaccurate and unreliable. We conclude that CI measurements have the potential to predict CP content and IVOMD of B. decumbens pastures. However, further calibration studies are needed to test the sensitivity of the chlorophyll gun under different growing conditions and also with pasture herbage that is sufficiently heterogeneous in chemical composition.

Intake and digestion of wethers fed with dwarf elephant grass hay with or without the inclusion of peanut hay.

The aim of this study was to evaluate the effect of the inclusion of peanut (Arachis pintoi cv. Amarillo) hay in diets based on dwarf elephant grass (DEG, Pennisetum purpureum Schum cv. Kurumi) hay of different regrowth ages on forage intake and digestibility in wether lambs. The experimental treatments consisted of DEG hay with an interval of regrowth of 30 or 45 days offered as the only feed or in mixture with peanut hay (300 g/kg of total dry matter (DM)), which were tested in eight Texel × Suffolk crossbred wethers in a replicated 4 × 4 Latin square experiment. Both organic matter (OM) and digestible OM intakes were higher (P < 0.05) in animals receiving the legume forage. Total apparent OM digestibility was higher (P < 0.05) at an increased grass regrowth age. Ruminal OM digestibility increased (P < 0.05) with legume inclusion and at a higher grass regrowth age. The nitrogen (N) intake was higher (P < 0.05) in legume treatments and lower (P < 0.05) as the grass regrowth age increased, but retention of N was not affected by treatments. Duodenal flow of both, non-ammonia N and microbial N, were not affected by legume inclusion and were lower (P < 0.05) as grass regrowth age increased. The efficiency of rumen microbial protein synthesis (ERMPS) was negatively affected (P < 0.05) by legume inclusion and was lower (P < 0.05) as the grass regrowth age increased. Supplementation of dwarf elephant grass hay cut at the vegetative stage with peanut legume hay improves nutritional supply to wethers due to an increase in the forage intake.

Amylase addition increases starch ruminal digestion in first-lactation cows fed high and low starch diets

The objective of this study was to evaluate the effect of an exogenous amylase preparation on digestion of low- and high-starch diets in dairy cattle. Rumen and total-tract nutrient digestibility were measured in a 4×4 Latin square design with 28-d periods using 4 first-lactation cows cannulated at the rumen and duodenum. Corn silage-based diets had 20 or 30% starch, attained by changing the composition of concentrate, with or without addition of an exogenous amylase preparation. Effects of the enzyme additive were observed on ruminal digestibility but not at the total-tract level. Ruminal digestibility of starch increased from 75% in control to 81% with amylase supplementation. This difference in ruminal starch digestion was compensated postruminally, so that the total-tract digestibility of starch was almost complete and did not differ between treatments. The amylase supplement also increased the true ruminal digestibility of organic matter but did not affect microbial N flow to the duodenum. Amylase supplement reduced the proportion of acetate and butyrate and increased that of propionate, particularly in the high-starch diet, where it tended to increase the concentration of total volatile fatty acids in the rumen. Other effects were a higher amylase activity in the solid-associated microbial community and a tendency for lower numbers of protozoa. In contrast, we observed no changes in intake, production, dry matter and fiber (neutral detergent fiber and acid detergent fiber) digestibility, or ruminal digestion, and no or small changes on selected fibrolytic and amylolytic bacteria and on the microbial community in general. We conclude that the exogenous amylase improved starch digestion in the rumen in first-lactation cows with moderate intake and production levels.

Enteric methane production, digestibility and rumen fermentation in dairy cows fed different forages with and without rapeseed fat supplementation

The purpose of this experiment was to study the effect of forage species (grass or maize) and the maturity stage of grass on enteric methane (CH4) production, nutrient digestibility and rumen fermentation, and to study possible interactions with cracked rapeseed as fat source. Six lactating, ruminal, duodenal and ileal cannulated Holstein dairy cows (206 days in milk, milk yield 25.1kg) were submitted to an incomplete Latin square design (6×4) with six diets and four periods. Two grass silages (early first cut, 361g aNDFom/kg DM and late first cut, 515g aNDFom/kg DM) and one maize silage were supplemented with either low fat concentrate or high fat concentrate. The dietary fat concentration in the high fat diets was approximately 60g/kg DM. Diurnal samples of duodenal and ileal digesta and feces were compiled. The CH4 production was measured for four days in open-circuit respiration chambers. Additional fat reduced the gross energy (GE) lost as CH4 from 6.3 to 5.8% of GE intake, independent of forage species and quality. Energy loss as CH4 constituted 6.1, 6.7 and 5.4% of GE intake for early grass silage, late grass silage and maize silage, respectively. However, there was no difference between early grass silage and maize silage when CH4 production was related to kg organic matter (OM) digested. Fat supplementation did not affect OM or aNDFom digestibility. Maize silage had a higher ruminal OM digestibility, but lower ruminal aNDFom digestibility than grass silage. Early cut grass silage had a higher total tract OM and aNDFom digestibility than late cut grass silage. The present study demonstrates that choice of forage species and harvest time affects CH4 emission from dairy cows, while the CH4 reducing ability of fat does not interact with forage characteristics.

Influence of feeding live yeast on microbial protein synthesis and nutrient digestibility in steers fed a steam-flaked corn-based diet

Four cannulated Holstein steers (264±5 kg) were used in a 4×4 Latin square design to evaluate the influence of feeding different levels (0, 10, 20, or 30 g/steer/d) of live yeast (LY) on microbial protein synthesis and characteristics of digestion of the finishing diet. The LY contained 5.5×109 CFU/g. Ruminal pH was not affected by LY supplementation. LY level decreased linearly duodenal flow of ruminal digestion of neutral detergent fiber (NDF) but did not affect duodenal flow of feed N, nonammonia N, or microbial N. LY supplementation did not affect ruminal digestion of organic matter (OM), N, microbial efficiency, or N efficiency but linearly increased ruminal digestion of NDF. Total tract digestion of OM, NDF, and digestible energy improved linearly as LY level supplementation increased. Supplemental LY improves NDF and OM digestion enough to improve the DE of the diet, and the level of supplementation affects the magnitude of the responses.

Metabolism and ruminal parameters of Holstein × Gir heifers fed sugarcane and increasing levels of crude protein

The objective of this study was to evaluate the effect of increasing levels of crude protein (CP) in the diet (13, 15, 19 and 22 g/100 g of dry matter, DM) on the metabolism and ruminal parameters of crossbred heifers fed forage sugarcane. Four crossbred Holstein × Gir heifers of average initial weight of 200 kg and average age of 14 months were used. The experimental design was in a 4 × 4 latin square. The intake values of DM, organic matter (OM), neutral detergent fiber (NDF) and non-fibrous carbohydrates (NFC) were not affected by the protein contents of the diet. The apparent and ruminal digestibility of DM and OM were affected by the protein content of the diet. Greater total apparent digestibility coefficient of CP (0.749) was observed for the content of 22 g CP/100 g DM, whereas the ruminal digestibility of CP was not affected by treatments. The efficiency of microbial protein synthesis was not different between the CP contents of the diet. There was increasing linear effect of the CP content in the diet on the plasma concentration of urea. The rumen pH of the heifers was similar between treatments, with an average of 6.3. The concentration of rumen ammonia nitrogen was affected by the protein content of the diet, with the highest averages at 22 and 19 CP/100 g DM (27.5 and 31.6 mg/dL); an average of 21.1 mg/dL in the diet with 15 g CP/100 g DM; and the lowest average observed in the diet containing 13 g CP/100 g DM, 14.0 mg/dL. It is recommended to use 13 g CP/100 g DM in the diet for crossbred Holstein × Gir heifers in the post-weaning phase consuming diets based on sugarcane, because this level promotes increase in the digestibility of the diet and lower concentrations of plasma urea nitrogen and ammonia nitrogen, showing better animal metabolism, in addition to a possible decrease in the cost of the diet.

Effect of fungal treatment on chemical composition and in vitro ruminal digestibility of some agricultural residues

II Incubator. For all data, a completely randomized design with a 4 × 2 factorial arrangement was used. The experimental factors were straw type at 4 levels (maize, wheat, rapeseed and soybean) and fungus application at 2 levels (T.447 and control). These findings show that crude protein, ether extract, ash, organic matter and cellulose, statistically, differed (P < 0.05) from straw type and fungus application. In vitro ruminal dry matter digestibility (IVRDMD), in vitro ruminal organic matter digestibility (IVROMD) and in vitro ruminal digestible organic matter in dry matter (IVRDOMD) differed significantly from straw type (P < 0.001) and fungus application (P < 0.05). The crude protein and ash concentrations increased (P < 0.05) in fungal-treated straws. The ether extract, organic matter, cellulose and in vitro ruminal digestibility values decreased (P < 0.05) in fungal-treated samples. These results obtained showed that the fungus has been active on the straws and had some desirable effects, such as enhancement of crude protein and undesirable effects, such as decrement of ether extract, organic matter and in vitro ruminal digestibility.

Influence of method of surfactant supplementation on characteristics of digestion and feeding value of fat in Holstein steers fed a high-energy finishing diet

Four Holstein steers (271 ± 11 kg) with cannulae in the rumen and proximal duodenum were used to study the influence of method of surfactant (Tween 80) supplementation on characteristics of digestion and feeding value of fat. Treatments consisted of a steam-flaked corn-based finishing diet supplemented with: (1) no supplemental fat, no surfactant; (2) 6% supplemental fat (yellow grease, no surfactant; (3) 5.75% supplemental fat plus 0.25% Tween 80 (TW) added to the diet as part of the premix (TW was mixed with premix before incorporation with grain in the mixer, as second step in diet preparation) and (4) 5.75% supplemental fat plus 0.25% TW combined directly with the supplemental fat (TW was mixed with supplemental fat before incorporation into the feed mix as penultimate step in diet preparation). There was no surfactant by supplemental fat interactions (p > 0.05). Surfactant did not affect (p > 0.05) site and extent of organic matter (OM), starch, N, acid detergent fiber (ADF) and fatty acid (FA) digestion, or digestible energy (DE) value of diet. Supplemental fat decreased (p < 0.05) ruminal and total tract digestion of OM and ADF and increased (p <0.05) the DE value of diet. The decrease in postruminal FA digestion was mainly due to decreased (p <0.05) digestion of C18:0. Digestible energy of supplemental fat averaged 6.87 Mcal/kg. It is concluded, that independent of method of addition, supplementing high-fat diets with 0.22% of Tween 80 does not influence site and extent of digestion or the feeding value of supplemental fat.

Effects of fungal infested steam-flaked corn on characteristics of ruminal and total tract digestion in steers

Four Holstein steers (407±4kg) with cannulas in the rumen and proximal duodenum were used in a 4×4 Latin Square design experiment. Treatments consisted of a 755g/kg steam-flaked corn-based finishing diet in which fungal infested steam-flaked corn replaced 0, 150, 300, and 450g/kg of the control flaked corn. The yeast and mold counts averaged 2.9×102, and 1.2×104CFU/g, respectively, for control flaked corn, and 7.0×105, and 6.2×106CFU/g, respectively, for fungal infested flaked corn. There were no treatment effects (P>0.10) on ruminal pH or volatile fatty acids molar proportions. Ruminal digestion of organic matter (OM; linear component, P<0.10), and feed N (linear component, P<0.05) decreased with increasing levels of fungal infested flaked corn in the diet. There were no treatment effects (P>0.10) on net microbial N synthesis. Amino acid intake increased linearly (P<0.01) as fungal infested flaked corn was augmented, and amino acid flow to duodenum was increased (P<0.01) with the highest fungal infested flaked corn level. Total tract digestion of OM, N and energy decreased (linear component, P<0.05) with increasing SFM. Ruminal and total tract digestion of ADF and starch were not affected (P>0.10) by treatments. It is concluded that mold infestation diminishes the feeding value of steam-flaked corn. The consequence was not related to effects of fungal growth on characteristics of digestion, but rather, to loss of readily digestible nutrients (starch) through the spoilage process, and to a lesser extent, decreased N digestibility. On the other hand, the metabolizable protein value was greater for fungal infested flaked corn.

Quantifying ruminal digestion of organic matter and neutral detergent fiber using the omasal sampling technique in cattle—A meta-analysis

A data set from 32 studies (122 diets) was used to evaluate the accuracy and precision of the omasal sampling technique by investigating the relationships between ruminal and total digestion of neutral detergent fiber (NDF), between intake and apparent and true ruminal digestion of organic matter (OM), and between omasal NAN flow and milk protein yield. A mixed model regression analysis with random study effect was used to evaluate the relationships. The data were obtained when feeding North American diets (n=36) based on alfalfa silage, corn silage, and corn grain and North European diets (n=86) comprising grass silage supplemented with barley-based concentrates. In all studies, digesta flow was quantified using a triple-marker approach. Standard deviations of ruminal NDF and true OM digestibility were smaller than typically reported in duodenal sampling studies using only chromic oxide as a flow marker. The relationship between total and ruminal NDF digestion was consistent, indicating little variation in the proportion of total-tract NDF digestion that occurred in the rumen. Furthermore, the slope of this regression indicated that 94.7% (±2.7%) of total NDF digestion occurred in the rumen. The slopes of mixed model regression equations between OM intake and amount digested indicated that 42% (±2.4%) and 74% (±3.1%) of OM was apparently and truly digested in the rumen, respectively. The contribution of the rumen to total-tract apparent OM digestion was 62% (±2.6%). The close relationship between omasal flow of nonammonia crude protein and milk protein yield (with adjusted residual mean squared error=31g) provided further confidence in the reliability of omasal flow measurements.

Avaliação nutricional do capim-elefante (Cameroon) em diferentes idades de rebrotação

Objetivou-se determinar o consumo e as digestibilidades aparente total, ruminal e intestinal de matéria seca (MS) e seus componentes: matéria orgânica (MO), proteína bruta (PB), extrato etéreo (EE), fibra em detergente neutro (FDN) e carboidratos não-fibrosos (CNF) do capim-elefante em diferentes idades de rebrotação e quantificar a produção de proteína microbiana. Utilizaram-se quatro novilhos mestiços, fistulados no rúmen e abomaso, alimentados à vontade com capim-elefante e sal mineral. O experimento foi avaliado considerando-se o grupo de animais como uma amostra aleatória simples, sendo os períodos de avaliação correspondentes às idades crescentes de rebrotação (33, 48, 63, 78 e 93 dias) e cada animal como medidas repetidas. Os consumos de matéria seca (MS), nutrientes digestíveis totais (NDT) e as digestibilidades totais dos demais nutrientes diminuíram linearmente com o aumento da idade de rebrotação. Os teores de MO, CNF e FDN apresentaram máximos consumos aos 44,43; 51,05 e 60,50 dias de rebrotação, respectivamente. O mínimo consumo de PB ocorreu aos 94,27 dias de rebrotação do capim. As digestibilidades ruminais da MS e MO aumentaram linearmente com o avanço da idade. Os compostos nitrogenados microbianos sofreram redução linear com o aumento da idade do capim-elefante. Recomenda-se usar o capim-elefante com idade entre 30 e 35 dias de rebrotação, quando se observou maior valor nutritivo da planta.

Effect of rare earth elements on in vitro rumen microbial fermentation and feed digestion

The objectives of this study were to investigate the effects of rare earth elements (REEs) on in vitro rumen fermentation, gas production, microbial protein synthesis and nutrient digestion using in vitro batch culture and continuous culture technique. A mixture of REE containing (g/kg) 380 g of LaCI 3·6H 2O, 521 g of CeCI 3·6H 2O, 30 g of PrCI 3·6H 2O and 69 g chlorides of other light REEs. The experimental diet consisted of 885 g/kg barley grain, 84 g/kg barley silage and 31 g/kg supplement (dry matter (DM) basis). Diet supplemented with different dosages of REE (control, no additional REE; low, 400 mg/kg REE; and high, 800 mg/kg REE, DM basis) were incubated for 4, 8, 14 and 24 h in diluted rumen fluid. At the end of 24 h of incubation, gas production and concentration of volatile fatty acid (VFA) linearly increased with increasing REE supplementation; whereas, influence of REE supplementation on VFA profile was marginal. Dry matter disappearance was not affected (P>0.10). Six dual-flow continuous culture fermenters were used in a replicated 3 × 3 Latin square with same treatments and same diet used in the batch culture. Mean ruminal pH (5.71) and total VFA (93.6 mM) concentration were not affected by supplementation of REE. The molar proportion (mol/100 mol) of acetate (39.1) and propionate (50.5) was similar among the treatments. However, the proportion (mol/100 mol) of butyrate was higher with the high REE (6.6) than with low REE (5.3) or the control (5.8). Ruminal true digestibilities of organic matter (OM) (0.785, 0.811 and 0.828), acid detergent fibre (0.360, 0.431 and 0.432) and crude protein (0.496, 0.590 and 0.589) for control, low and high REE, respectively, linearly increased with increasing REE supplementation, whereas, the increase in ruminal digestibility from low to high dosage of REE was minimal. Microbial nitrogen (N) production (g/day) and microbial efficiency (g N/kg of truly fermented OM) were not affected by treatments. Improvement of ruminal digestibility of OM due to REE supplementation was attributed to the increase in digestibility of fibre and degradability of protein. The results suggest that REE supplementation improved ruminal fibrolytic and proteolytic activities.

Intake, rumen fermentation and nutrient flow to the omasum in beef cattle fed grass silage fortified with sucrose and/or supplemented with concentrate

The objective was to determine the relative effects of a specific increase in grass silage sucrose concentration, or a specific supplement of a starch-based concentrate, on rumen fermentation and nutrient supply to the omasum in beef cattle. Four ruminally cannulated Holstein–Friesian steers were fed grass silage only (G), G plus 3 kg concentrates/day (GC), G plus 90 g sucrose/kg dry matter (DM) (GS) and G plus 90 g sucrose/kg DM plus 3 kg concentrates/day (GCS) in a 4 × 4 Latin Square design experiment. Omasal flow was estimated using Co-EDTA, Yb-acetate and indigestible neutral detergent fibre (INDF) as digesta flow markers and purine bases as microbial markers. Concentrate supplementation reduced ( P < 0.01) silage and increased ( P < 0.001) total DM intake whereas sucrose had no effect. There was a sucrose × concentrate interaction ( P < 0.05) for rumen pH whereby addition of sucrose to grass silage alone decreased pH and to grass silage plus concentrate had no effect. Rumen ammonia N ( P < 0.01), total volatile fatty acid (VFA) concentration ( P < 0.05) and the molar proportions of valerate ( P < 0.05) and butyrate ( P < 0.001) increased with concentrate supplementation whereas, sucrose supplementation had no effect on rumen fermentation parameters. Organic matter (OM) intake, omasal OM flow, the quantities of OM apparently (OMAD) and truly digested (OMTD) in the rumen ( P < 0.001) and total tract OM digestibility ( P < 0.01) increased, and apparent and true ruminal OM digestibility decreased ( P < 0.05) with concentrate supplementation. Supplementation with concentrate decreased ( P < 0.05) ruminal neutral detergent fibre (aNDFom) digestibility and increased ( P < 0.05) aNDFom omasal flow. There was a tendency for addition of sucrose to increase ( P < 0.1) ruminal OMAD and OMTD, while there was no effect of sucrose addition on intake or digestion of aNDFom. Concentrate supplementation increased ( P < 0.001) N intake, flows of N, non-ammonia N (NAN), microbial N (MN) ( P < 0.05) and non-ammonia non-microbial N (NANMN) ( P < 0.01) and apparent total tract digestibility of N ( P < 0.01), whereas sucrose reduced ( P < 0.05) N intake and apparent ruminal N digestibility. There was no effect of concentrate or sucrose on N use efficiency or efficiency of microbial protein synthesis. Concentrate supplementation increased ( P < 0.001) plasma β-hydroxybutyrate levels. In comparison to supplementing unwilted, well preserved grass silage of moderate digestibility with 3 kg starch-based concentrate per day, the limited response to the rate of sucrose supplementation employed suggests that increasing the water-soluble carbohydrate (WSC) concentration of grass silage through agronomic and/or ensiling practices will have relatively little effect on intake, rumen digestion or efficiency of microbial N synthesis.

Effect of dietaryEnterolobium cyclocarpumon microbial protein flow and nutrient digestibility in sheep maintained fauna-free, with total mixed fauna or withEntodinium caudatummonofauna

Three groups of five wethers with ruminal and duodenal cannulas and maintained as either fauna-free (FF) or inoculated with total mixed fauna (TF) or Entodinium caudatum as a single-species monofauna (EN) were used in an experiment with two 28 d periods. In the first period, the sheep were fed a control barley-based diet (40:60 concentrate to silage DM) and in the second period the diet was supplemented with 187 g DM of Enterolobium cyclocarpum for the last 12 d of the period. The diets of period 1 and 2 were isonitrogenous. There was no effect of fauna on apparent ruminal and total tract organic matter and fibre digestion, but bacterial and microbial N flow and efficiency were improved in FF sheep compared to TF sheep. In period 2, protozoal numbers were reduced between 31 and 88 % 2 h after feeding E. cyclocarpum for the third to twelfth day of supplementation and by an average of 25 % in samples collected over the 24 h feeding cycle. Supplementation of the diet with E. cyclocarpum and the consequent protozoal reduction in TF and EN sheep improved the flow of non-ammonia N and bacterial N to the small intestine and the efficiency of microbial synthesis. However, E. cyclocarpum reduced ruminal organic matter digestion, especially in faunated sheep, and total tract organic matter, N and fibre digestion. Thus, a reduction in the protozoal cell numbers of 25 % was sufficient to achieve the beneficial effects of reduced fauna on the bacterial protein supply, but diet digestibility was reduced.

Effects of Fatty Acid Supplements on Ruminal and Total Tract Nutrient Digestion in Lactating Dairy Cows

Saturated and unsaturated fatty acid supplements (FS) were evaluated for effects on ruminal digestion kinetics, and ruminal and postruminal nutrient digestion. Eight early lactation ruminally and duodenally cannulated cows (77±12 days in milk, mean±SD) were used in a replicated 4×4 Latin square design experiment with 21-d periods. Treatments were control and a linear substitution of 2.5% fatty acids from supplemented saturated FS (SAT; prilled, hydrogenated free fatty acids) for partially unsaturated FS (UNS; calcium soaps of long-chain fatty acids). All rations contained identical forage and concentrate components including 37.2% forage and 13.5% cottonseed. Saturated FS linearly decreased ruminal digestibility of dry matter and organic matter and linearly decreased ruminal neutral detergent fiber (NDF) digestibility. The reduction in ruminal NDF digestibility was because of a linear decrease in digestion rate and a linear increase in passage rate of potentially digestible NDF with increasing saturated FS. Total tract digestibility of NDF was not different between treatments because of compensatory postruminal digestion. Ruminal fatty acid and C18 fatty acid digestibility tended to increase linearly with increasing unsaturated FS, and postruminal C18 fatty acid digestibility decreased with increasing saturated FS. Saturated FS linearly decreased ruminal organic matter digestibility and decreased intestinal long-chain fatty acid digestibility, although differences in fatty acid digestibility may be partially explained by fatty acid intake.

Effect of dietary inclusion of hazelnut and soybean meals on microbial protein synthesis

The aim of this study was to compare effects of dietary inclusion of hazelnut meal (HZM) with soybean meal (SBM) on site of digestion and microbial protein synthesis in sheep. Four ruminally and duodenally cannulated female Redkaraman × kıvırcık sheep (initial BW of 44.0 ± 1.02 kg) were utilized in a crossover experiment. Sheep were fed a diet of 60% corn silage (DM basis) and 40% concentrate consisting of barley and SBM or HZM. Feed was fed at 115% of ad libitum intake. Intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were similar between sheep fed SBM or HZM based diets ( P > 0.05). Organic matter intake averaged 1089 (2.37% BW) and 1143 g/day (2.42% BW) for SBM and HZM, respectively. Apparent and true ruminal and total tract DM and OM digestibilities did not differ between diets ( P > 0.05). True ruminal OM digestibility was 74.3 and 74.6% for SBM and HZM based diets, respectively. Total CP entering the duodenum was similar between diets ( P > 0.05). Dietary plus endogenous CP entering the duodenum in grams and as a percentage of total CP was greater ( P < 0.05) for SBM versus HZM. Quantities of microbial protein ( P < 0.15) and NH 3 N ( P < 0.08) flowing to the duodenum tended to be less for SBM versus HZM; percentages of total CP were lower ( P < 0.05) for SBM. Apparent ruminal and total tract CP digestibilities did not differ between diets, but true ruminal CP digestibility and efficiency of microbial protein synthesis tended to be higher in animals fed the HZM based diet compared with the diet based on SBM ( P < 0.13). In conclusion, because total CP entering duodenum did not differ between diets, HZM can be substituted for SBM in sheep fed corn silage and barley based diets with a moderate CP level.

Effect of pelletizing on the feeding value of rice straw in steam-flaked corn growing-finishing diets for feedlot cattle

Trial 1. Three cannulated crossbred steers were used to compare the effects of ground versus pelletized rice straw on characteristics of digestion. Treatments consisted of a steam-flaked corn-based diet containing 120 g/kg sudangrass (SG, positive control), ground rice straw (GRS) or pelletized rice straw (PRS). Ruminal digestion of organic matter was similar across treatments ( P<0.10). Ruminal digestion of neutral detergent fiber was low, averaging 140 g/kg, and not affected ( P>0.10) by forage source. Ruminal starch digestion was lower (5%; P<0.05) for sudangrass than for rice straw diets, and greater (8%, P<0.01) for pelletized versus ground straw. Ruminal microbial efficiency was greater (9.7%; P<0.05) for ground than for pelletized rice straw. Total tract digestion of dry matter was greater (3%, P<0.10) for sudangrass than for rice straw treatments and NDF digestion was lower (26%; P<0.05) for rice straw than for sudangrass diets. Total tract starch digestion was greater (2%, P<0.01) for pelletized than for ground rice straw diets, due largely to greater ruminal starch digestion. Treatment effects were numerically similar for ground sudangrass and ground rice straw diets. Pelletized rice straw increased ( P<0.05) ruminal total volatile fatty acid (VFA) and propionate concentrations by 24 and 47% respectively, and decreased ruminal pH (9%, P<0.05), ruminal acetate:propionate molar ratio (27%, P<0.05), and estimated methane production (28%, P<0.05). Trial 2. Ninety crossbred yearling steers were used in a 112 day finishing trial to evaluate the influence of pelletizing on the feeding value of rice straw. Treatments were the same as Trial 1. Substituting ground rice straw for sudangrass had no detrimental effects ( P>0.10) on energy intake or average daily gain (ADG). However, DMI and ADG were greater (11%, P<0.05, and 12%, P<0.10, respectively) for ground than for pelletized rice straw supplemented diets. There were no treatment effects ( P>0.10) on dressing percentage, which had a carcass to live weight ratio averaging 0.642. Steers fed the sudangrass diet had a lower yield grade (16%; P<0.01), marbling score (13%; P<0.05), and fat thickness (15%; P<0.10) than those fed the rice straw diets. Feeding pelletized straw reduced marbling score (10%, P<0.10), and fat thickness (20%; P<0.10) when compared with ground rice straw. As expected, NE m and NE g were greater (5%; P<0.01) for sudangrass than for rice straw diets. Pelletizing rice straw did not decrease ( P=0.56) the dietary net energy (NE) value of the rice straw supplemented diets. Thus, the difference in ADG due to feeding ground versus pelletized rice straw is attributable solely to treatment effects on DMI. We conclude that at lower levels of rice straw inclusion (<150 g/kg) fed to steers in growing-finishing diets, pelletizing the straw may reduce intake and gain through a satiety response mechanism, possibly associated with increased propionate production.

Effects of exogenous amylases from Bacillus licheniformis and Aspergillus niger on ruminal starch digestion and lamb performance

Two industrial exogenous enzymes, alpha-amylase from Bacillus licheniformis and glucoamylase from Aspergillus niger, were evaluated in vivo and in lambs fed 700 g/kg (dry matter (DM)) sorghum grain diets. Six Suffolk lambs (30 ± 2.5 kg body weight (BW)) fitted with ruminal and duodenal cannulas were randomly allotted to two 3 × 3 Latin square experiments, to evaluate effects of alpha-amylase and glucoamylase on intake, digestibility and ruminal fermentation. The same level of protein from the two enzyme sources (0.0, 1.45 or 2.90 g enzyme/kg DM sorghum) was applied to sorghum. The enzymes were sprinkled on the sorghum 24 h before mixing the diet. The highest level of each enzyme was also fed (45 days) to 15 individually housed lambs (Suffolk crossbred, 22.5 ± 1.4 kg BW) in a completely randomized design (i.e., control, alpha-amylase or glucoamylase) to evaluate lamb performance. The highest activity units/mg protein ( P < 0.01) was for the alpha-amylase (4.190) followed by glucoamylase (1.952) and ruminal fluid (0.062). Dry matter, organic matter (OM) and starch intake decreased as level of dietary alpha-amylase increased (linear: P < 0.05), but ruminal starch digestion and total tract digestibility of DM, OM and starch increased quadratically ( P < 0.05). Total volatile fatty acids VFA and protozoa numbers decreased linearly ( P < 0.01), whereas lactate was quadratically ( P < 0.01) increased with alpha-amylase. Ruminal pH, protozoa and lactate increased ( P < 0.01) with glucoamylase. Propionate molar proportion responded quadratically ( P < 0.01) with both enzymes. The intermediate level of glucoamylase increased intake of DM, OM and starch (quadratic: P < 0.09), but total tract starch digestibility decreased (linear: P = 0.08) as level of glucoamylase increased. Feed intake, gain and feed conversion were not affected by enzymes, but alpha-amylase improved ( P < 0.05) partial feed efficiency. Results indicate that amylase from B. licheniformis increases ruminal starch digestion and could be used to improve ruminal starch digestion in ruminants fed diets high in grains with low digestion rates.

Determination of Rumen Degradability and Ruminal Effects of Three Sources of Methionine in Lactating Cows

Objectives were to quantify the ruminal effects and flows to the omasum of Met provided as 2-hydroxy-4-(methylthio)-butanoic acid (HMB), the isopropyl ester of HMB (HMBi), and dl-Met. Eight ruminally cannulated cows were used in a replicated 4×4 Latin square design. Treatments were 1) no Met (control), 2) HMB at 0.10% of DM, 3) HMBi at 0.13% of DM, and 4) dl-Met at 0.088% of DM. Diets were identical except for type of Met supplement and were based on corn silage and alfalfa hay at 30 and 13% of dietary DM, respectively. Samples of omasal fluid were used to determine the proportion of Met supplements passing out of the reticulorumen. Dry matter intake (20.1 kg/d) was restricted during the week of sampling to a maximum of 95% of ad libitum DMI determined during the first 2 wk of the period. Milk yields (37.7±0.8 kg/d) and fat concentration (3.42±0.15%) were not significantly different for control, HMB, HMBi, and dl-Met. Milk protein concentration (2.91, 2.95, 3.02, 2.96±0.07%, respectively) was significantly increased by the HMBi treatment. Rumen volatile fatty acids profile and NH3 concentrations were similar across treatments. Apparent ruminal digestibility of organic matter and neutral detergent fiber were higher for the three diets supplemented with Met sources than for the control diet. In situ rate of digestibility of CP from alfalfa hay, TMR, and corn silage was affected by Met sources. Passage rates of small particles (0.071/h) and fluid (0.167/h) were not affected by treatments. Protozoal counts in the rumen and omasum were not significantly affected by Met sources. Proportion of omasal N from bacterial N was not different (0.54±0.03), and bacterial N flow (305±24.4 g/d) was similar across treatments. The proportion of HMB that passed into the omasum was 5.3±1.5% of the amount consumed. Only a small amount (2.3%) of HMBi was found as HMB in the omasum. These results indicate that little HMB escapes ruminal degradation through passage to the omasum and that the site of HMBi absorption must be preomasal.