Digestion In Steers Research Articles

Germination ecology and growth phenology of cowvine (Ipomoea lonchophylla) as influenced by environmental parameters

AbstractCowvine (Ipomoea lonchophylla J.M. Black) is a native and widely spread summer broadleaf weed in Australia. It contains glycoresins, which are toxic to livestock. However, limited information is available on seed germination ecology and growth phenology of this species. A series of experiments were conducted to determine the response of I. lonchophylla to different environmental conditions. Results showed that the primary dormancy exhibited by I. lonchophylla is due to the physical impediment of the hard seed coat. The seed germination percentage was the highest at the constant temperature of 27 C and alternating temperatures of 35/25 C. Germination of I. lonchophylla was not stimulated by light, suggesting that this species is non-photoblastic. Ipomoea lonchophylla germination was intolerant of a medium to high level of salt stress, and germination was completely inhibited at 250 mM NaCl. The emergence of I. lonchophylla was not restricted by seeding depth up to 8 cm, but only 5% emergence was recorded when seeds were planted at a 16-cm depth. The germination percentage was also drastically reduced by 90% to 100% after exposure to either 3 mo in silage, 48-h digestion in steers, or silage plus digestion treatments. The growth and reproductive phenology of I. lonchophylla was affected by emergence time. Plants that emerged in late spring (November 15) were able to produce more berries per plant than those that emerged in midsummer (January 15) in southern New South Wales. Information gained in our study concerning high soil salinity, ensiling, and digestion will help to develop more sustainable and effective integrated weed management strategies for controlling and reducing the spread of this weed.

Effect of synchronization of fermentation processes in body of young cattle

Indicators of rumen digestion of young cattle has been studied when fed with concentrates with high level of degradable protein and non-structural carbohydrates subjected to barothermal treatment. Extrusion of concentrated feed decreases degradability of concentrates protein by 26-28%. Correlation of indicators of rumen digestion in steers with the method of preparation for feeding with concentrates with high level of degradable protein and non-structural carbohydrates has been determined. So, in animals receiving feed subjected to barothermal treatment, the number of ciliates in rumen fluid increases by 5.4%, total nitrogen – by 2.9%, and concentration of ammonia and volatile fatty acids decreases by 8.1 and 3.4% Thus, processing of concentrates stimulates development of microflora of proventriculus and reduces the rumen protein loss. Barothermal treatment of concentrates with a high protein degradability and high level of non-structural carbohydrates increases productivity of animals and efficiency of feed. The average daily weight gain in animals of experimental group increases by 4.8-6.0%. As a result, the feed cost is reduced by 2.7-6.9%, and protein – by 2.6-5.7%.

The Impact of Ensiling at Different Moisture Contents on Germinability and Viability of Selected Weed Species’ Seeds

Weeds are an increasingly significant issue inhibiting agricultural production worldwide. Forage conservation could form part of an integrated weed management program if ensiling killed weed seeds. In Experiment 1, seeds of five grass (Hordeum spp., Bromus diandrus, Bromus hordeaceum, Lolium rigidum and Vulpia spp.) and two broad-leaved temperate weed species (Echium spp. and Raphanus raphanistrum), that were either untreated, ensiled in pasture (Trifolium subterranean/Lolium rigidum mixture) forage for a minimum of three months, underwent 48 h in sacco digestion in steers or ensiled prior to digestion were tested for germinability and viability. In Experiment 2, seeds of eight tropical weed species (Cenchrus ciliaris, Rumex spp., Bidens pilosa, Sorghum halepense, Urochloa panicaoides, Paspalum dilatatum, Brachiara eruciformis and Choris truncata) were ensiled in Sorghum bicolor forage. In Experiment 3, L. rigidum and R. raphanistrum seeds were ensiled in either Medicago sativa forage wilted to 336.9, 506.5 or 610.7 g/kg dry matter; or in chaff to which water or water plus acid was added at rates to achieve 350, 450 or 550 g/kg dry matter content with lactic plus acetic acid added in the ratio of 3:2 at 80, 45 or 10 g/kg DM, respectively. In Experiment 4, L. rigidum and R. raphanistrum seeds were ensiled in cotton wool to which water or water plus acid was added at the same rates as in Experiment 3. Germinability of all seeds following ensiling was substantially reduced or nil. The extent of the reduction varied with species and experiment. In sacco digestion reduced germinability in Experiment 1, but to a lesser extent than ensiling; while ensiling plus digestion reduced germination rates to 0%.

Isoquinoline Alkaloids and the Ionophore Monensin Supplemented Alone or Combined on Ruminal Fermentation and Nutrient Digestibility in Steers Fed a High-Energy Diet

Isoquinoline Alkaloids and the Ionophore Monensin Supplemented Alone or Combined on Ruminal Fermentation and Nutrient Digestibility in Steers Fed a High-Energy Diet

Protein-energy supplementation frequency on ruminal variables, intake and digestibility in steers receiving low quality hay

Abstract The aim was evaluated the effect of reduce in protein-energy supplementation frequency on nutrients intake, forage digestibility and degradability, as well as, ruminal pH and ammonia nitrogen (N-NH3) concentration in beef cattle receiving low-quality hay. A 4 x 4 Latin square design were used. Four steers were fed with low-quality hay and subjected to four treatments: no supplementation (control); protein-energy supplementation with 0.82% of body weight (BW) offered three times per week (3WK); 0.49% of BW offered five times a week (5 WK), and 0.35% of BW offered seven times per week (7 WK). The use of protein-energy supplementation increased intake of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), ether extract (EE), non-fibrous carbohydrates (NFC) and the digestibility coefficients of CP, EE, and NFC. However, no differences in DM and NDF degradation visit the website to get the how were observed between treatments in the evaluated hay. Supplementation did not alter ruminal pH, but the N-NH3 concentration was highest in treatment 7WK. Reduction in protein-energy supplementation frequency of daily to 3WK or 5WK does not negatively affect intake, digestibility and degradability of nutrients in beef cattle receiving low quality hay.

Trace mineral source influences ruminal distribution of copper and zinc and their binding strength to ruminal digesta1,2,3.

Eight crossbred steers (BW 719.0 ± 65.0 kg) with ruminal and duodenal cannulae were used to examine the effect of trace mineral (TM) source on digestibility; ruminal and duodenal solubility of Cu, Zn, and Mn; and in vitro release of Cu, Zn, and Mn from the solid fraction of ruminal digesta. Experiment 1 determined the effect of TM source on DM and NDF digestibility in steers fed a corn silage and steam-flaked corn-based diet. Treatments consisted of 10 mg Cu, 20 mg Mn, and 30 mg Zn/kg DM from either sulfate TM (STM) or hydroxy TM (HTM) sources. Following a 14-d adaptation period, total fecal output was collected for 5 d. Dry matter digestibility was not affected by treatment, but NDF digestibility tended (P < 0.09) to be greater in HTM vs. STM supplemented steers. In Exp. 2, steers were fed a diet without supplemental Cu, Zn, or Mn for 19 d. Steers were then administrated a pulse dose of STM or HTM (2× the National Research Council requirements for Cu, Mn, and Zn) via the rumen fistula. Ruminal and duodenal samples were obtained at 2-h intervals starting at -4 and ending at 24 h relative to dosing. Ruminal soluble Cu and Zn concentrations were affected by treatment, time, and treatment × time. Soluble concentrations and percent soluble Cu and Zn in ruminal digesta increased (P < 0.05) above 0-h values for 10 h following dosing with STM, but not HTM. Concentrations of Cu and Zn in ruminal solid digesta were also affected by treatment, time, and treatment × time. Steers dosed with STM had greater (P < 0.05) solid digesta Cu concentrations at 2 and 4 h but lesser (P < 0.05) concentrations from 6 to 20 h post-dosing than those receiving HTM. Ruminal solid digesta Zn concentrations were greater (P < 0.05) in HTM vs. STM-dosed steers from 6 through 24 h post-dosing. Distribution of Mn in ruminal digesta was affected by TM source, but to a lesser extent than Zn and Cu. Duodenal soluble TM concentrations were variable and not affected by treatment. Binding strength of TM to ruminal solid digesta was estimated at 0, 6, and 12 h post-dosing using dialysis against chelating agents. The percentage of Cu and Zn released from ruminal solid digesta by dialysis against Tris-EDTA was greater (P < 0.05) at 12 h post-dosing from steers receiving HTM vs. STM. Results indicate that Cu and Zn from HTM have low solubility in the rumen and appear to be less tightly bound to ruminal solid digesta than Cu and Zn from STM.

Effect of ensiling and in sacco digestion on the viability of seeds of selected weed species

SummaryThe germinability and viability of mature seeds of five grass (Hordeum spp., Bromus diandrus, Vulpia spp., Avena fatua and Lolium rigidum) and seven broad‐leaved weed species (Echium spp., Physalis hederifolia, Solanum elaeagnifolium, Raphanus raphanistrum, Marrubium vulgare and Malva parviflora) that were either untreated, ensiled for a minimum of three months, underwent 48 h in sacco digestion in steers or ensiled prior to digestion were tested for germinability and viability. Ensiling and digestion both reduced seed viability, although the extent varied with species. The effect of ensiling was generally greater compared with digestion and differed between years for some species. Ensiling or ensiling plus digestion rendered all seeds of Hordeum spp., B. diandrus, Vulpia spp., A. fatua, Echium spp., P. hederifolia (in one year only), S. elaeagnifolium, R. raphanistrum and M. vulgare non‐viable; ensiling and ensiling plus digestion reduced viability of L. rigidum by 74.4% and 92.7% respectively. Viability of M. parviflora displayed the greatest tolerance to damage, with seed viability reduced on average by 31.4%, 27.6% and 27.4% for ensiling, digestion and ensiling plus digestion treatments respectively. These results indicate that ensiling can provide an effective non‐chemical weed management option, as a component of an integrated weed management package, for certain weed species responsible for significant crop and pasture production losses in Australian and world temperate and Mediterranean agricultural systems.

Effects of conservation method and crushing method of rice grain on rumen fermentation and nutrient digestibility in steers

We evaluated the effects of different methods for conserving and crushing rice grain on rumen fermentation characteristics and whole-tract apparent digestibility in steers. The preparation of dietary treatments followed a 2×2 factorial design with conservation method (drying vs. ensiling) and crushing method (using an impeller crusher vs. a double–roller crusher) of rice grain as main effects. Rice grain was crushed by the impeller crusher (volume weight: 490.4g/L, mean particle size: 1382μm) or the double–roller crusher (volume weight: 373.9g/L, mean particle size: 2043μm). Dried rice was prepared by drying to adjust the moisture to 100gkg−1. Ensiled rice was prepared by sealing crushed rice with the addition of water and lactic acid bacteria to adjust the moisture to 300gkg−1, and stored for 4 months. Eight ruminally cannulated steers (366±32.2kg initial body weight [BW]) were randomly assigned to a replicated 4×4 Latin square design. The experimental diets contained 434gkg−1 grass silage, 96gkg−1 soybean meal and 470gkg−1 treated rice grain (dry matter [DM] basis). Steers were offered experimental diets at 1.55kg DM/100kg of BW/day. The conservation method had a large impact on the ruminal fermentation and nutrient digestibility. The ruminal fermentation characteristics and nutrient digestibility (except for starch digestibility) were not affected by the crushing method. No significant interactions were observed between the conservation and crushing methods of rice grain for all fermentation and digestion measurements. The ruminal pH was lower (P<0.01) and the lactic acid and total volatile fatty acid concentrations were higher (P<0.01 and P=0.02, respectively) for the steers fed ensiled rice than those fed dried rice. The proportions of acetate, propionate and butyrate were not affected by ensiling treatment. The whole-tract apparent digestibility of organic matter, crude protein and starch were increased (P=0.04, P<0.01 and P<0.01, respectively) and the digestibility of neutral detergent fiber and acid detergent fiber were decreased (P=0.046 and P=0.03, respectively) by replacing dried rice with ensiled rice. The starch digestibility was higher (P<0.01) for steers fed rice crushed by the impeller crusher compared to the double-roller crusher. These results show that the feeding of ensiled instead of dried rice increases the likelihood of decreasing fiber digestibility because it reduces ruminal pH, but it improves organic matter, crude protein and starch digestion, and thus an ensiling process can be a strategy to improve the nutrient value of rice grain.

Effect of Vitamin E on Ruminal Fermentation and Nutrient Digestion in Steers Supplemented with Microencapsulated Conjugated Linoleic Acid

The aim of this study was to evaluate the effect of vitamin E on ruminal fermentation and nutrient digestion in steers supplemented with microencapsulated conjugated linoleic acid (CLA). Four male rumen- and duodenum-cannulated Holstein steers (450±93 kg) were used in a 4×4 Latin square design, randomly assigned to four treatments: control (basal diet with 50g of microencapsulated CLA) and the same supplemented with three levels of vitamin E at 4000, 8000, or 12000 IU/d. The supplements (CLA and vitamin E) were placed intra-ruminally. The basal diet consisted of 68% of concentrate and 32% of forage. DM intake was restricted to 2.1% of the initial LW. Chromium oxide was administrated as inert digesta marker via ruminal cannula. There were no significant differences in ruminal pH and production of VFAs due to vitamin E; but butyrate and total VFAs concentration tended to decrease. Also, vitamin E treatments tended to increase acetate:propionate ratio. Ruminal digestion of CP tended to decrease and flow to duodenum of CP tended to increase. Faecal excretion of DM and OM decreased significantly (P<0.05), while total-tract digestion of DM and OM increased significantly (P<0.05) with vitamin E. In conclusion, vitamin E improves total-tract digestibility of DM and OM in steers supplemented with microencapsulated CLA. This suggests that vitamin E could improve the gastrointestinal conditions, impacting positively the productive performance of animals.

1401 Effects of supplementation of isoquinoline alkaloids and monensin on microbial protein synthesis, ruminal fermentation and nutrient digestibility in steers fed a finishing diet

1401 Effects of supplementation of isoquinoline alkaloids and monensin on microbial protein synthesis, ruminal fermentation and nutrient digestibility in steers fed a finishing diet

Influence of Feeding Enzymatically Hydrolyzed Yeast Cell Wall on Growth Performance and Digestive Function of Feedlot Cattle during Periods of Elevated Ambient Temperature.

In experiment 1, eighty crossbred steers (239±15 kg) were used in a 229-d experiment to evaluate the effects of increasing levels of enzymatically hydrolyzed yeast (EHY) cell wall in diets on growth performance feedlot cattle during periods of elevated ambient temperature. Treatments consisted of steam-flaked corn-based diets supplemented to provide 0, 1, 2, or 3 g EHY/hd/d. There were no effects on growth performance during the initial 139-d period. However, from d 139 to harvest, when 24-h temperature humidity index averaged 80, EHY increased dry matter intake (DMI) (linear effect, p<0.01) and average daily gain (ADG) (linear effect, p = 0.01). There were no treatment effects (p>0.10) on carcass characteristics. In experiment 2, four Holstein steers (292±5 kg) with cannulas in the rumen and proximal duodenum were used in a 4×4 Latin Square design experiment to evaluate treatments effects on characteristics of ruminal and total tract digestion in steers. There were no treatment effects (p>0.10) on ruminal pH, total volatile fatty acid, molar proportions of acetate, butyrate, or estimated methane production. Supplemental EHY decreased ruminal molar proportion of acetate (p = 0.08), increased molar proportion of propionate (p = 0.09), and decreased acetate:propionate molar ratio (p = 0.07) and estimated ruminal methane production (p = 0.09). It is concluded that supplemental EHY may enhance DMI and ADG of feedlot steers during periods of high ambient temperature. Supplemental EHY may also enhance ruminal fiber digestion and decrease ruminal acetate:propionate molar ratios in feedlot steers fed steam-flaked corn-based finishing diets.

Effects of including saponins (Micro-Aid®) on intake, rumen fermentation and digestibility in steers fed low-quality prairie hay

Sixteen ruminally cannulated crossbred steers (529±45kg initial body weight, BW) were used to evaluate in situ dry matter (DM), neutral detergent fiber (aNDF), and N degradation characteristics of low-quality prairie hay, blood urea-N (BUN) and rumen fermentation parameters in steers provided a protein supplement with or without Micro-Aid® (MA; plant derived saponin). Steers were allowed ad libitum access to chopped prairie hay (49g crude protein (CP)/kg DM and 738g aNDF/kg DM) and randomly assigned to one of four treatments: (1) no supplement (C), (2) cottonseed meal and wheat middlings: 920g DM/d (PC; positive control), (3) MA added to PC to supply 1g MA/d (MA1), and (4) MA added to PC to supply 2g MA/d (MA2). Steers were individually supplemented 920g DM once daily at 08:00 along with a vitamin and mineral mix to ensure requirements were met. Orthogonal contrasts were used to determine the effects of protein supplementation, addition of MA and level of MA inclusion. During in situ phase, forage samples were incubated for a 96h period. Protein supplementation increased DM intake (DMI), particulate passage rate (Kp), and rumen digestibility of DM and NDF (P<0.001), but there was no effect on rumen N degradability. The inclusion of MA did not impact DMI in either phase. Compared to PC, MA decreased Kp (27.8 and 22.7g DM/kg/h, respectively; P=0.02), resulting in an increase in rumen aNDF and DM digestibility (P<0.001). However, there was no influence of MA on apparent total tract digestibility in the metabolism phase. Rumen protozoa concentrations were suppressed (P=0.01) with MA inclusion while lactate concentrations and microbial crude protein (MCP) flow to the small intestine were increased (P=0.05). There was no impact on BUN, rumen ammonia, pH, volatile fatty acid (VFA) concentrations or N balance for MA compared to PC diets. Supplementation improved N balance, MCP synthesis and increased total concentrations of VFA and independent acetate and propionate concentrations. In conclusion, including MA in protein supplements increased rumen DM and a NDF digestibility of forage, reduced protozoa concentrations and increased daily outflow of MCP. This is indicative of increased rumen fermentation rate and may ultimately impact animal performance via increased energy and amino acid supply to the small intestine. However, more research is needed to validate this potential impact on animal performance.

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.

Effects of 2-methylbutyrate on rumen fermentation, ruminal enzyme activities, urinary excretion of purine derivatives and feed digestibility in steers

The objective of this study was to evaluate the effects of 2-methylbutyrate (2MB) supplementation on rumen fermentation, ruminal enzyme activities, urinary excretion of purine derivatives and feed digestibility in the total tract of steers. Eight ruminally cannulated Simmental steers were used in a replicated 4×4 Latin square experiment. The treatments were: control (without 2MB), L2MB, M2MB and H2MB with 8.4, 16.8 and 25.2g 2MB per steer per day, respectively. 2-methylbutyrate was hand-mixed into the concentrate portion. Diet consisted of 60% corn stover and 40% concentrate (dry matter [DM] basis). Dry matter intake (averaged 9kg/d) was restricted to a maximum of 90% of ad libitum intake. Ruminal pH was linearly decreased, whereas total VFA concentration (range of 64.19–71.06mM) was linearly (p<0.01) and quadratically (p<0.01) increased with increasing 2MB supplementation. Ratio of acetate to propionate increased linearly (p<0.01) from 2.53 to 3.80 as 2MB supplementation increased due to the increased in acetate production and decreased in propionate production. Activities of CMCase and xylanase were linearly increased, whereas that of protease was linearly reduced with increasing 2-methylbutyric supplementation. In situ ruminal NDF degradation of corn stover was improved but the CP degradability of soybean meal was decreased with increasing 2MB supplementation. Urinary excretion of purine derivatives was quadratically (p<0.01) changed with altering 2MB supplementation (52.74, 58.50, 59.17 and 54.36mmol/d for control, low, medium and high 2MB supplementation, respectively). Similarly, digestibilities of DM, NDF and CP in the total tract were also linearly and quadratically increased with increasing 2MB supplementation. The present results indicate that supplementation of diet with 2MB improved rumen fermentation and feed digestion in beef cattle. It was suggested that the 2MB stimulated the digestive microorganisms or enzymes in a dose-dependent manner. In the experimental conditions of this trial, the optimum 2MB dose was about 16.8g 2MB per steer per day.

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.

Influence of fibrolytic enzymes on growth performance and digestion in steers grazing stargrass and supplemented with fermented sugarcane

An experiment was conducted to evaluate the influence of exogenous fibrolytic enzymes on growth performance and digestion in steers grazing stargrass and supplemented with concentrate and sugarcane fermented. Solid state fermentation of sugar cane (SSFSC) was whole sugarcane chopped, added (dry matter basis) with urea (1.5%) and mineral premix (0.5%), and kept under shadow for 24 h. Twenty crossbreed (Brahman × Brown Swiss) steers (287±14.1 kg) grazing stargrass were individually supplemented with SSFSC (free access for 1-h period) and concentrate (1 kg/head) by 100 d. Steer were randomly assigned to concentrate with 0, 15 or 30 g fibrolytic enzyme/kg concentrate. As enzyme level increased, daily gain, intake, digestion, and improved feed conversion were linearly improved.

Effects of Fibrolytic Enzymes on Ruminal Fermentation and Digestibility in Steers Fed Diets with Sodium Bicarbonate

Montañez-Valdez, O.D., Pinos-Rodríguez, J.M., Martínez-Tinajero, J.J., Rojo-Rubio, R., Salinas-Chavira, J. and Avellaneda-Cevallos, J.H. 2010. Effects of fibrolytic enzymes on ruminal fermentation and digestibility in steers fed diets with Sodium bicarbonate. J. Appl. Anim. Res., 38: 191–196. The objective of this study was to evaluate the effect of exogenous fibrolytic enzymes (ENZ) on ruminal fermentation and disappearance in steers fed high-concentrate diets with sodium bicarbonate (SB, 3% of total diet). Six ruminally cannulated steers (450±15 kg) were randomly assigned to a replicate 3×3 Latin square. Experimental high-concentrate diets (70% concentrate DM) were as follow: control; ENZ (0.3% enzymes) and ENZ+BS (0.3% enzymes plus 3% SB). Dry matter intake, ruminal pH, ammonia N, ruminal disappearance of dry matter and neutral detergent fiber of diets were not affected by ENZ or ENZ+SB. Steers fed ENZ and ENZ+SB spent more time ruminating and resting and less time eating than steers on control diet. Ruminal pH and ammonia N concentrations in steers fed ENZ+BS were greater than in steers fed ENZ or not supplemented. There were scarce effects of fibrolytic enzymes on Ruminal disappearance and fermentation of high-concentrate diet with sodium bicarbonate for steers.

Effects of exogenous fibrolytic enzymes on intake, duodenal flow, and digestion in steers fed diets with whole or cracked Pima cottonseed

This study evaluated the effects of exogenous fibrolytic enzymes on intake, ruminal fermentation, and duodenal flow and digestion of nutrients in steers fed diets with whole Pima cottonseed (WPC) or cracked Pima cottonseed (CPC). Four Holstein steers (167±5 kg body weight) fitted with ruminal and duodenal cannulas with a 4×4 Latin square in a 2×2 factorial arrangement of treatments (WPC or CPC; 0 or 15 g enzyme) were used. Steers were fed wheat flaked-based diets with 9.95% of WPC or CPC as dry matter basis. Enzymes increased molar proportion of acetate in steer fed WPC, but in those fed CPC acetate decreased. Feeding enzymes increased duodenal flow of organic matter in steers fed WPC, but not in those fed CPC. Also, enzymes increased duodenal flow of N, non-ammonia N, and intestinal digestion of N in steers fed WPC and CPC.

Effects of isovalerate on ruminal fermentation, urinary excretion of purine derivatives and digestibility in steers

The objective of this study was to evaluate the effects of isovalerate supplementation on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in the total tract of steers. Eight ruminally cannulated Simmental steers were used in a replicated 4 · 4 Latin square experiment. The treatments were: control (without isovalerate), low isovalerate (LIV), medium isovalerate (MIV) and high isovalerate (HIV) dosage of isovalerate at 100, 200 and 300 mg isovalerate per kg dry matter (DM) intake respectively. Diets consisted of corn stover and concentrate (60/40, DM basis). Dry matter intake was approximately 9 kg per day that was 90% of ad libitum intake including 5.4 kg corn stover and 3.6 kg concentrate. Ruminal pH (6.72–6.54) was linearly (p < 0.03) reduced, whereas total volatile fatty acid concentration (64.6–74.7 mmol/l) was linearly (p < 0.01) and quadratically (p < 0.01) increased with increasing isovalerate supplementation. Ratio of acetate to propionate increased linearly (p < 0.01) from 2.78 to 3.39 as isovalerate supplementation increased because of the increase in acetate production and decrease in propionate production. In situ ruminal degradation of amylase-treated neutral detergent fibre (aNDF) of corn stover was improved, but crude protein (CP) degradability of soybean meal decreased with increasing isovalerate supplementation. Urinary excretion of purine derivatives was quadratically (p < 0.01) changed by altering isovalerate supplementation (50.5, 54.3, 58.9 and 55.2 mmol/day for control, LIV, MIV and HIV, respectively). Similarly, digestibilities of organic matter, aNDF and CP in the total tract were linearly and quadratically increased with increasing isovalerate supplementation. The results of this study indicate that supplementation of diet with isovalerate improved ruminal fermentation and feed digestion in beef cattle. It was suggested that the isovalerate stimulated the digestive microorganisms or enzymes in a dose-dependent manner.

Effects of citric acid supplementation on rumen fermentation, urinary excretion of purine derivatives and feed digestibility in steers

AbstractBACKGROUND: An increase feed efficiency and rate of gain were observed from addition of sodium citrate to the diet of fatting lamb. It is suggested that the small amounts of citric acid (CA) may have a catalytic effect on rumen microbial metabolism which would result in a potential means of increasing feed efficiency. The objective was to evaluate the effects of CA supplementation on rumen fermentation, ruminal microbial production by measuring urinary excretion of purine derivatives, and digestibility in the total tract of steers.RESULTS: Ruminal pH linearly (P = 0.01) decreased, whereas total volatile fatty acid concentration linearly (P = 0.01) increased with increasing CA supplementation. Ratio of acetate to propionate linearly (P = 0.01) increased due to the increase in acetate production. Urinary excretion of purine derivatives was quadratically (P = 0.02) changed, with the lowest for control, medium for low CA and highest for medium and high CA supplementation. Similarly, digestibilities of nutrients in the total tract were also linearly and quadratically increased with increasing dosages of CA.CONCLUSION: Supplementation of CA increased rumen acetate concentration and thus increased ratio of acetate to propionate. Urinary excretion of purine derivatives and total digestibility were improved. In the experimental conditions of this trial, the optimum citric acid dose was about 200 g citric acid per steer per day. Copyright © 2009 Society of Chemical Industry