Improved Fiber Digestion Research Articles

73 Effects of Fatty Acids Sources and Lysophospholipids on Nutrient Digestibility in Lactating Cows

Abstract Fatty acids (FA) are a common supplement for lactating cows to increase energy supply, potentially improving feed efficiency and milk and milk fat yields. However, different FA can cause varying responses probably because of different FA digestibility and interactions with other nutrients (e.g., fibers). Lysophospholipids (LPL) are natural emulsifiers and LPL as a feed additive have shown increases in FA digestibility and nutrient absorption in non-ruminant animals. This study aimed to investigate the effects of FA sources with LPL supplementation on nutrient digestibility in lactating cows. Mid-lactation cows (n = 48) were allocated into 12 blocks, and cows in each block were randomly assigned to the following dietary treatments:1) a diet with a FA supplement [1.8% of dietary dry matter (DM)] mainly containing palmitic acid (PA); 2) the PA diet with LPL (0.003% of dietary DM); 3) a diet with a FA supplement (1.8% of dietary DM) mainly containing stearic acid (SA); and 4) the SA diet with LPL (0.003% of DM). The experiment was conducted for 6 weeks, and spot samples of feces and urine were collected over 3 days (every 3 hours within a 24-hour cycle) during the last week of the experiment to determine nutrient digestibility and utilization. Data were analyzed using the mixed model with FA source, LPL, and their interaction as fixed effects and block as a random effect. The digestibility of DM, organic matter, and crude protein were not affected by the FA source and no interaction between FA and LPL was observed. However, PA had greater neutral detergent fiber (NDF) digestibility (41.4 vs. 38.8%; P = 0.04) than SA with no interaction between the FA source and LPL. In addition, as expected, PA decreased (P < 0.01) the digestibility of 16-carbon FA compared with SA due to the greater C16:0 supply, and SA decreased (P < 0.01) that of 18-carbon FA compared with PA due to the greater C18:0 supply. Supplementation of LPL did not affect digestibility of DM, OM, CP, and NDF, but increased total FA digestibility (64.7 vs. 60.5%; P = 0.02) compared with no LPL. In addition, LPL increased 18-carbon FA digestibility (68.2 vs. 74.1%; P < 0.01) compared with no LPL. An interaction between LPL and FA was observed for 16-carbon digestibility because LPL increased 16-carbon digestibility with SA but not with PA. In conclusion, PA supplementation improved fiber digestibility compared with SA, which could be a factor for increased productivity (e.g., milk fat). Supplementation of LPL was effective in increasing FA digestibility and may have potential to increase dietary energy supply or provide a similar energy supply with less dietary fat content in practice. However, more studies are needed to understand different interactions of LPL with FA sources.

The effect of corn silage hybrid and inclusion on performance of finishing steers and silage hybrid effects on digestibility and performance of growing steers.

Three experiments evaluated the effects of three corn silage hybrids, inclusion, and nutrient digestibility in growing and finishing diets. The three hybrids tested included a control (CON), a hybrid containing a brown midrib (bm3) trait (BM3), and an experimental bm3 hybrid with the soft endosperm trait (BM3-SOFT). Experiment 1 utilized 360 crossbred steers (body weight [BW] = 334; SD = 25 kg) to evaluate inclusion of silage in a finishing diet at (15% or 45% of diet dry matter [DM]) and silage hybrid (CON, BM3, or BM3-SOFT). Experiment 2 and 3 utilized 216 crossbred steers (BW = 324; SD = 10 kg) and six ruminally fistulated steers (BW = 274; SD = 27 kg), respectively, to evaluate effects of either CON, BM3, or BM3-SOFT silage hybrids on performance and nutrient digestibility in growing diets. In Exp. 1, there was a silage inclusion × hybrid interaction for average daily gain (ADG) and gain-to-feed ratio (G:F). All treatments with 15% silage had greater (P ≤ 0.04) ADG and G:F compared with 45% silage. Cattle fed BM3-SOFT had greater ADG and G:F than cattle fed CON or BM3 when silage was included at 15% of the diet. When silage was fed at 45% of the diet DM, ADG did not differ between cattle fed either bm3 hybrid. Cattle fed BM3 had the greatest G:F (P < 0.01), with no difference between BM3-SOFT and CON. At 15% silage inclusion, hot carcass weight (HCW) was greater (P < 0.01) for cattle fed BM3-SOFT compared with cattle fed CON and BM3 but did not differ between cattle fed BM3 and CON. At 45% silage inclusion, steers fed either bm3 hybrid did not differ in HCW but were both heavier (P < 0.01) compared with cattle fed CON. In Exp. 2, ending BW, dry matter intake (DMI), and ADG were greater (P < 0.01) for steers fed either bm3 hybrid compared to steers fed the CON, but not different between steers fed the bm3 hybrids. There were no differences (P = 0.26) in G:F between the silage hybrids. In Exp. 3, steers fed either bm3 had greater (P < 0.01) neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility than steers fed the CON. Ruminal pH was lower (P < 0.01), and total volatile fatty acid (VFA) concentration was greater (P < 0.01) for steers fed bm3 hybrids compared to steers fed CON. Feeding silage with the bm3 trait improved fiber digestibility, which increased DMI and subsequent ADG in high-forage growing diets. Feeding corn silage with the bm3 trait improved performance compared to non-bm3 corn silage when included above typical roughage concentration.

Effects of Exogenous Fibrolytic Enzyme Derived from Trichoderma reesei on Rumen Degradation Characteristics and Degradability of Low-Tannin Whole Plant Faba Bean Silage in Dairy Cows

The objectives of this study were to (1) determine the effect of exogenous fibrolytic enzyme derived from Trichoderma reesei on dry matter (DM) and neutral detergent fibre (NDF) degradability of whole plant faba bean silage (Snowbird), (2) evaluate the effects of fibrolytic enzyme (FETR) on DM and NDF degradation kinetics of whole plant faba bean silage, and (3) compare the difference between in the vitro approach (DaisyII incubation method) and the in situ assay-biological approach (nylon bag technique) in the determination of degradability of dry matter (DMD) and neutral detergent fibre (NDFD). The fibrolytic enzyme from Trichoderma reesei was a mixture of xylanase and cellulase. The whole plant faba bean silage was treated with seven doses of fibrolytic enzyme, with 0 as a control and 0.25, 0.5, 0.75, 1, 1.25 and 1.5 mL of FETR/kg DM of silage. The results obtained from the in situ method show that fibrolytic enzyme cubically (p &lt; 0.05) affected DMD and quadratically (p &lt; 0.01) affected NDFD with increasing level of enzyme application. In vitro DM and NDF degradability were quadratically and cubically (p &lt; 0.01) affected by the increasing dosage of enzyme. Correlation analysis between the in situ assay-biological approach and the In vitro DaisyII approach showed a strong correlation (r = 0.98, p &lt; 0.01) on overall DMD and also a satisfactory relationship (r = 0.84, p &lt; 0.01) was found on overall NDFD. The enzyme application showed a great impact on NDF rumen degradation kinetics by decreasing the undegradable fraction and increasing the potential degradable fraction and the effective degradable content of fiber. The washable (W) and potential degradation fraction (D) were linearly (p = 0.05) increased by the enzyme treatments. Therefore, the undegradable fraction was linearly decreased (p = 0.05) with increasing dosage of enzyme. Both bypass (BNDF) and effective degradable NDF (EDNDF) were cubically (p = 0.05) affected by fibrolytic enzyme. In conclusion, the exogenous fibrolytic enzyme derived from Trichoderma reesei highly impacted rumen degradation characteristics and degradability of whole plant faba bean silage and could be used to improve fibre digestion of whole plant faba silage in dairy cows.

In Vitro Application of Exogenous Fibrolytic Enzymes from Trichoderma Spp. to Improve Feed Utilization by Ruminants

Treating ruminant feeds with exogenous fibrolytic enzymes may potentially increase forage cell wall degradability and thus feed efficiency. In nature, fungi biosynthesize lignocellulolytic enzymes that can break down lignocellulosic material into its sugar components, thereby providing ready fermentable substrates. This work showed the in vitro fibrolytic activity of three Trichoderma strains (T. atroviride strain P1, T. afroharzianum strain T22, T. reesei strain T67). Total protein concentration and enzymatic (e.g., glucanase, cellulase, and xylanase) activities were determined in fungal culture filtrates after 7 and 14 days of growth on different fiber-based media. The enzymatic mixtures produced by Trichoderma spp. showed the highest concentration of fibrolytic enzymes and were added to industrial feed to test their ability to hydrolyze insoluble fibers. The supplementation of industrial feeds containing medium-fiber or low-fiber concentrates with T22 enzymes produced in the presence of lyophilized mushrooms and durum wheat fiber reduced hemicellulose concentration up to 33% and 24%, respectively. These results may offer novel opportunities to develop livestock feeds with improved fiber digestibility.

Intensive mechanical processing of forage crops to improve fibre digestion

AbstractTwo intensive forage processing mechanisms, utilising either shredding or impact processing, were used to investigate physical disruption of wilted alfalfa and whole‐plant corn as a potential means to improve fibre digestion. Physical disruption was quantified by a processing level index (PLI) defined as the ratio of treatment leachate conductivity relative to that of an ultimately processed treatment. The goal was to achieve a PLI of at least 60%. Impact processing created more physical disruption than shredding, and the former method was able to achieve the desired PLI goal. Although impact processing significantly reduced particle size of both wilted alfalfa and whole‐plant corn, more than 40% of alfalfa particles were longer than 6.3 mm when the PLI of greater than 60% was achieved. The mean particle‐size of the kernel fraction of processed whole‐plant corn was less than 1 mm after processing with the impact processor. Impact processing of wilted alfalfa significantly increased the rapidly soluble fraction and increased the rate of degradation of DM and potentially digestible fibre (pdNDF) during an in situ digestion experiment. Intensive mechanical processing has the potential to improve ruminant animal utilisation of forage crops through improved fibre digestion.

Milk production and efficiency of utilization of nitrogen, metabolizable protein, and amino acids are affected by protein and energy supplies in dairy cows fed alfalfa-based diets

Alfalfa has a lower fiber digestibility and a greater concentration of degradable protein than grasses. Dairy cows could benefit from an increased digestibility of alfalfa fibers, or from a better match between nitrogen and energy supplies in the rumen. Alfalfa cultivars with improved fiber digestibility represent an opportunity to increase milk production, but no independent studies have tested these cultivars under the agroclimatic conditions of Canada. Moreover, decreasing metabolizable protein (MP) supply could increase N use efficiency while decreasing environmental impact, but it is often associated with a decrease in milk protein yield, possibly caused by a reduced supply of essential AA. This study evaluated the performance of dairy cows fed diets based on a regular or a reduced-lignin alfalfa cultivar and measured the effect of energy levels at low MP supply when digestible His (dHis), Lys (dLys), and Met (dMet) requirements were met. Eight Holstein cows were used in a double 4 × 4 Latin square design, each square representing an alfalfa cultivar. Within each square, 4 diets were tested: the control diet was formulated for an adequate supply of MP and energy (AMP_AE), whereas the 3 other diets were formulated to be deficient in MP (DMP; formulated to meet 90% of the MP requirement) with deficient (94% of requirement: DMP_DE), adequate (99% of requirement: DMP_AE), or excess energy supply (104% of requirement; DMP_EE). Alfalfa cultivars had no significant effect on all measured parameters. As compared with cows receiving AMP_AE, the dry matter intake of cows fed DMP_AE and DMP_EE was not significantly different but decreased for cows fed DMP_DE. The AMP_AE diet provided 103% of MP and 108% of NEL requirements whereas DMP_DE, DMP_AE, and DMP_EE diets provided 84, 87, and 87% of MP and 94, 101, and 107% of NEL requirements, respectively. In contrast to design, feeding DMP_EE resulted in a similar energy supply compared with AMP_AE, although MP supply has been effectively reduced. This resulted in a maintained milk and milk component yields and improved the efficiency of utilization of N, MP, and essential AA. The DMP diets decreased total N excretion, whereas DMP_AE and DMP_EE diets also decreased milk urea-N concentration. Reducing MP supply without negative effects on dairy cow performance is possible when energy, dHis, dLys, and dMet requirements are met. This could reduce N excretion and decrease the environmental impact of milk production.

520 Late-Breaking: Effect of Technology on Environmental Emissions from Four Representative U.S. Feedlots and the Beef Production System

Abstract Our objective was to evaluate effects of technological management strategies on environmental impacts and net returns of feedlot operations in the United States. Feedlot operations were simulated with the Integrated Farm System Model (IFSM 4.6; USDA-ARS, University Park, PA) to quantify baseline environmental impacts of feedlot production and full US beef cattle production systems. Strategies simulated included: ionophore, implant, ractopamine hydrochloride, combined management (ionophore, implant, and ractopamine hydrochloride; I+I+R), lubabegron, reduced mortality rate, and improved fiber digestion. Days on feed were adjusted whenever necessary and according to production practices typical of commercial feedlots. Subsequently, annual number of cattle finished by the operation was adjusted according to days on feed to maintain consistent one-time capacities. Mitigation strategies were individually modeled and simulated in IFSM for each feedlot operation to calculate intensities (expressed per kg gain) for greenhouse gas (GHG) emissions, fossil energy use, blue water consumption, and reactive nitrogen loss. Additionally, net returns to management were estimated for each feedlot operation. Feedlots were then integrated with simulations of cow-calf, stocker, and backgrounding operations to estimate environmental intensities (expressed per kg carcass weight) for the full beef cattle production system. Carbon emission intensity was reduced most using the I+I+R strategy (10%), followed by implant (6%) and ionophore (5%) strategies alone. Similarly, energy use intensity was reduced the greatest by I+I+R (9%), ionophore (5%), and implants (4%). Reductions in water use intensity were also greatest using I+I+R (9%). Net returns increased for all strategies compared to baseline net return with the greatest improvements observed for I+I+R ($114/finished animal) and implants ($66/animal). Consistent results were observed for all strategies simulated across all four environmental intensities when quantified for the full cattle production system. Implementing I+I+R (7%), ractopamine hydrochloride (4%), and lubabegron (4%) in feedlots resulted in the greatest reductions in environmental emissions.

PSX-B-8 Effect of supplementing red osier dogwood extract on in vitro gas production, feed digestibility and fermentation characteristics of high-forage diet

Abstract Red osier dogwood (ROD) is native shrub plant in Canada and rich in bioactive compounds. The objective of this study was to evaluate the effects of ROD extract supplementation in a high-forage (HF) diet on gas production (GP), dry matter (DM) disappearance (DMD) and fermentation characteristics in batch cultures with varying media pH. The study was a completely randomized design with 4 levels of ROD extract (0, 1, 3 and 5% of substrate) × 2 media pH (5.8 and 6.5) factorial arrangement. The study was conducted in three replicate experiments. Substrate contained 60% barley silage and 40% barley concentrate (DM basis). Inoculum was obtained from 2 ruminally fistulated beef heifers offered the HF diet. Substrate (0.5 g DM) ground (1 mm) was incubated for 48 h in a culture bottle. Data were analyzed using Mixed procedure of SAS with fixed effects of treatments and random effect of experiment. There was no interaction between media pH and level of ROD on GP, DMD and fermentation characteristics. Increased media pH (5.8 vs. 6.5) increased (P &amp;lt; 0.01) GP (averaged 164 vs. 275 ml/g substrate), DMD (50.6 vs. 60.6%), and total VFA production (63 vs. 71 mM). Increasing ROD extract levels did not affect GP but linearly (P = 0.05) decreased DMD from 62.1 to 58.9% at pH 6.5. Although total VFA production was not affected, increasing ROD extract linearly (P &amp;lt; 0.01) increased the proportion of acetate (47.9 to 49.7%) and propionate (20.5 to 22.3%) at pH 5.8; whereas at pH 6.5, acetate to propionate ratio quadratically (P = 0.04) changed to be lower with 3% ROD extract (2.08) than other treatments (2.21). These results indicated that supplementation of HF diet with ROD extract may improve fibre digestion at low media pH, and improve fermentation efficiency at high media pH.

Application of Selected Inoculant Producing Antifungal and Fibrinolytic Substances on Rye Silage with Different Wilting Time

This research was conducted to determine the effects of selected inoculant on the silage with different wilting times. The ryes were unwilted or wilted for 12 h. Each rye forage was ensiled for 100 d in quadruplicate with commercial inoculant (Lactobacillus plantarum sp.; LPT) or selected inoculant (Lactobacillus brevis 100D8 and Leuconostoc holzapfelii 5H4 at 1:1 ratio; MIX). In vitro dry matter digestibility and in vitro neutral detergent fiber digestibility were highest in the unwilted MIX silages (p &lt; 0.05), and the concentration of ruminal acetate was increased in MIX silages (p &lt; 0.001; 61.4% vs. 60.3%) by the increase of neutral detergent fiber digestibility. The concentration of ruminal ammonia-N was increased in wilted silages (p &lt; 0.001; 34.8% vs. 21.1%). The yeast count was lower in the MIX silages than in the LPT silages (p &lt; 0.05) due to a higher concentration of acetate in MIX silages (p &lt; 0.05). Aerobic stability was highest in the wilted MIX silages (p &lt; 0.05). In conclusion, the MIX inoculation increased aerobic stability and improved fiber digestibility. As a result of the wilting process, ammonia-N in silage decreased but ruminal ammonia-N increased. Notably, the wilted silage with applied mixed inoculant had the highest aerobic stability.

13 Impact of Biome Fix on the fecal microbiome response to antibiotic challenge in horses

Antibiotic (AB) therapies commonly used by veterinarians to treat bacterial infections can have side effects that stem from a disruption of the hindgut microbiota with a reduction of celluloytic bacteria and a proliferation of pathogenic strains. In practice, many veterinarians recommend a direct fed microbial (DFM) along with AB as DFM have been shown to mitigate some of the effects of AB on fecal microbiota. However, many commercially available DFM supplements also contain prebiotics, and there is little research on these microbial support supplements during AB administration. The purpose of this study was to determine the impact of Biome Fix (NutraWorks Equine) during AB treatment on fecal microbiome. Biome Fix is a blend of prebiotics (MOS, FOS, and Asperigullus niger extract), DigestaWell® Buffer (Probiotech International, Inc.), and DigestaWell® Fiber (Probiotech International, Inc.). Both DigestaWell® Buffer and Fiber have been previously shown to buffer fecal pH through reduced lactate production, and improve fiber digestibility in horses, respectively. Horses (n = 16) were assigned (blocked by age, sex, and BCS) to either Control (C:no supplement) or Biome Fix (BF:480g/d) for the 27d trial period. At d 0, all horses received AB (trimethoprim plus sulfadizine tablets (Uniprim) at 30mg/kg/d) for 7d. Fecal samples were collected at d 0, 7, 21, and 27. After DNA extraction from samples, the V3–V4 region of the bacterial 16S rRNA gene was amplified by PCR and amplicons were sequenced using Illumina MiSeq. Sequence analysis was conducted in QIIME 2, taxonomy was assigned against the SILVA database, and pair-wise t -tests were used to determine differences. Between d 0 and 27 in BF, there was an increase in Clostridium butyricum , a butyrate producer ( P = 0.037), Anaerovibrio sp., a lipid degrader ( P = 0.02), and 3 groups of Ruminococcaceae involved in fiber digestion ( P < 0.02), and a decrease in Treponema ( P = 0.02). Four groups associated with obesity in human and animal gut microbiomes were significantly lower in BF than C at d 27: Rikenellaceae RC9 ( P = 0.009), Eubacterium spp. ( P = 0.044), Clostridiales Family XIII AD3011 ( P = 0.04), and Lachnospiraceae UCG-009 ( P = 0.04). No common pathogens ( Salmonella spp., Escherichia coli , or Clostridium perfringens ) were detected in either group or time point. Due to the role of butyrate in intestinal health, an increase in butyrate producers may strengthen intestinal integrity during AB challenge. The increase in strains involved in fiber and lipid digestion may indicate improved digestibility and a greater capacity for resilience in the face of AB challenge; however, more research is warranted.

183 A blend of plant extracts (Actifor Pro) potentially reduced methane production in a dual-flow continuous culture system fed bermudagrass hay with or without corn gluten feed

Abstract Twelve dual-flow continuous culture fermenters (1.95 L) were used to evaluate the effect of a phytogenic feed additive (Actifor Pro, Delacon, Engerwitzdorf, Austria; ACT) on ruminal fermentation and methane production when fed high fiber diets, comprised of bermudagrass hay (BGH) with or without corn gluten feed (CGF). Fermenters were utilized in a generalized randomized block design with a 2 × 2 factorial arrangement of treatments (n = 6): 1) diet (with or without CGF at 22% of diet DM) and 2) additive (with or without ACT at 1.0 g/L ACT). Two 10-d periods were conducted. Overall, comparing to no CGF, supplementation with CGF resulted in lower dry matter, organic matter, crude protein digestibility, microbial efficiency of nitrogen utilization, and methane production (mL of CH4/mol of total VFA), but increased neutral detergent fiber digestibility (all P ≤ 0.05). Diet × additive interactions were observed for molar proportion of acetate and propionate, and acetate-to-propionate ratio (A:P, all interactions P &amp;lt; 0.05), where inclusion of ACT increased acetate molar proportion and A:P (both P &amp;lt; 0.05), and decreased propionate molar proportion in diets with CGF (P = 0.05). A diet × additive interaction was also observed for methane production (ml of CH4/mol of total VFA; P = 0.08), where ACT decreased CH4 production per mol of VFA by 42% (P = 0.04), when only BGH was fed to the fermenters. In conclusion, CGF supplementation in BGH diets reduced methane production and improved fiber digestibility. The decrease in methane production per mol of VFA observed with ACT in the BGH without CGF diet warrants further investigation.

161 Effects of management strategies on environmental footprints of cow-calf production in the United States

Abstract Estimates of beef cattle production’s national and regional cradle to farm grate environmental impacts have been quantified. As baseline footprints are now established, cow-calf dietary and production management strategies can be evaluated for their capacity to reduce environmental impacts. Accordingly, our objective was to quantify environmental changes from implementing management strategies in cow-calf production. Ten management strategies were identified, with each related to animal performance, feed management, or pasture management. Each strategy was incorporated into a representative cow-calf operation for each of 6 major regions of beef production in the United States and simulated with the Integrated Farm System Model (IFSM) using local soil and climate data. A combined strategy was also identified based on results of the individual strategies, which was simulated with IFSM. Farm-gate life cycle assessment was used to estimate carbon (C) footprint, fossil energy use, blue water use, and total reactive nitrogen (N) loss for all production systems and strategy combinations. Averages of each environmental metric for the cow-calf sector were based on weighted averages of regional cow inventory data. Averaged across all strategies, the reduction in C footprint was 4.1% and fossil energy use was reduced 3.5% for the cow-calf sector. Improved feed efficiency (8.0%) and terminal cross (7.1%) strategies reduced C footprint to a greater extent than other strategies simulated (2.0%). Fossil energy use was reduced by 8.3, and 6.5% from improved feed efficiency and terminal cross strategies, respectively. Early weaning increased C footprint, fossil energy use, blue water use, and reactive N loss by 13.8, 17.8, 20.2, and 12.7%, respectively. The combined strategy, including improved feed efficiency, improved fiber digestion, calf implant use, increased weaning rate, reduced cow body weight, and terminal cross strategies, reduced C footprint (18%), fossil fuel use (18%), blue water use (23%), and reactive N loss (15%).

160 Effects of cow-calf management strategies on environmental footprints of beef cattle production in the United States

Abstract As baseline environmental footprints of beef cattle production are established, mitigation strategies through cow-calf dietary and production management can be evaluated. Our objective was to quantify environmental benefits obtained by beef cattle production through implementation of cow-calf management strategies. Ten cow-calf management strategies were identified related to animal performance, feed management, or pasture management. Each strategy was incorporated into 20 representative beef cattle production systems and simulated with the Integrated Farm System Model (IFSM) using local soil and climate data. A combined strategy was identified based upon the results of individual strategies, which was also simulated with IFSM. Farm-gate life cycle assessment was used to estimate carbon (C) footprint, fossil energy use, blue water use, and total reactive nitrogen (N) loss for all production systems and strategy combinations. Averages of each environmental metric for the cow-calf sector were based on weighted averages of regional cow inventory data. National estimates of environmental impacts were based upon number of cattle represented by each production system. Feed efficiency, terminal cross sires, and reduced cow body size strategies had greatest effect on C footprint (reductions of 1.31, 1.15, and 0.71 kg CO2e/kg CW, respectively from a baseline of 16.34 kg CO2e/kg CW). Calving season, reduced cow body size, and improved fiber digestion increased fossil energy use (7.8%), while improved feed efficiency and calf implant use reduced fossil energy use (7.4%). Blue water use was reduced by a greater extent from improved feed efficiency (4.6%) and reduced cow body size (5.3%) compared to other strategies (0.6%). Total reactive N loss was reduced by 7.0 and 6.9% through improved feed efficiency and reduced cow body size, respectively. Combining strategies reduced C footprint (18.2%), fossil energy use (18.6%), blue water use (18.9%), and reactive N loss (16.2%).

2 Evaluation of Masters Choice Corn Silage on Growing Steer Performance

Abstract Corn hybrids can be selected for improved digestion rates using lab techniques, which should impact animal performance. The objective of this study was to evaluate two Masters Choice corn silage hybrids on growing steer performance. In an 84-day growing study, 288 crossbred steers (initial BW = 303 ± 12 kg) were utilized in a generalized randomized block design with three diet treatments, 12 steers per pen and 8 pen replicates per treatment. Diets consisted of 80% corn silage (DM basis) of Masters Choice hybrid MCT6365 RIB (MC1, that has been selected to improve fiber and starch digestion) and MCT6733 GT3000 (MC2, that has been selected to improve fiber digestion) were compared to a conventional corn hybrid Farm Choice (CON, that is commonly grown in Eastern Nebraska). All corn was grown in one field under identity preserved method and harvested at 37-38% DM in three consecutive days. Relative to CON, feeding MC1 resulted in similar dry matter intake (DMI, P = 0.28), but numerically increased average daily gain (ADG, P = 0.14) which significantly improved feed efficiency (G:F, P = 0.02). Feeding MC2 led to greater DMI (P &amp;lt; 0.01), similar ADG (P = 0.45), and lower G:F (P &amp;lt; 0.01) compared to CON. The results suggest that feeding Masters Choice hybrid MCT6365 RIB (MC1) corn silage at 80% of the diet DM improved ADG and G:F by 4.2%, while feeding MC2 decreased G:F by increasing DMI compared to CON. Differences in corn hybrids exist when feeding growing cattle 80% silage.

Performance and milk composition of Holstein cows fed with dried malt bagasse and selenium-enriched Saccharomyces cerevisiae

• Addition of selenized Saccharomyces cerevisiae did not improve fiber digestibility. • Use of selenium-enriched yeast increased the milk selenium concentration. • Use of selenium-enriched yeast had no effect oxidative stability of the milk. • Inclusion of malt bagasse reduced energy intake and microbial protein synthesis. • Inclusion of 24% dried malt bagasse reduced energy-corrected milk production. The objective of this study was to evaluate the effect of selenium-enriched Saccharomyces cerevisiae on the performance, composition and quality of milk from cows fed diets containing dried malt bagasse. Eight Holstein cows were distributed in a 4 × 4 double Latin square. The treatments were in a 2 × 2 factorial scheme: with or without the inclusion of malt bagasse x with or without the addition of selenium-enriched Saccharomyces cerevisiae . Dried malt bagasse was included at 24% in the dry matter (DM) of the diet; the amount of yeast supplied was 15 g/day and was composed of strain Saccharomyces cerevisiae CNCM I-1077 containing 1.0 × 10 9 CFU/g and 170 mg selenium/kg. Cows fed diets containing malt bagasse presented lower intakes of DM, crude protein and non-fibrous carbohydrates (NFC) and higher intakes of ethereal extract and neutral detergent fiber (P < 0.05). The digestibility of DM and the NFC of the diets with malt bagasse were lower in relation to the diets without this ingredient (P < 0.01). The addition of yeast did not influence the intake and digestibility of nutrients or any blood parameters. The levels of cholesterol and triglycerides of cows fed malt bagasse were higher than those that did not receive this by-product (P < 0.01). There was an interaction for blood urea, wherein the concentrations of the malt bagasse diet were higher than the diets without bagasse and without bagasse with yeast (P < 0.05). Cows fed diets without malt bagasse and with yeast produced more microbial protein than those fed with malt bagasse and yeast (P < 0.05). The use of selenium-enriched Saccharomyces cerevisiae had no effect on the production, composition and oxidative stability of the milk, but increased the milk selenium concentration (P < 0.05). The inclusion of malt bagasse reduced energy-corrected milk production, fat, protein, casein and total solids content of milk (P < 0.05), and increased milk urea nitrogen and the conjugated diene concentration (P < 0.01). Thus, the use of selenium-enriched Saccharomyces cerevisiae in the diet of lactating cows increased the selenium concentration, but did not improve the production and oxidative stability of the milk, whereas the inclusion of dried malt bagasse reduced energy intake, energy-corrected milk production and the milk fat and protein contents.

PSXII-23 Effects of a recombinant fibrolytic enzyme on fiber digestion, ruminal fermentation, nitrogen balance and total tract digestibility of heifers fed a high forage diet

Abstract The objective of this study was to investigate the effects of a recombinant fibrolytic enzyme (RFE; xylanase XYL10C) on ruminal pH and fermentation characteristics, total tract digestibility and nitrogen balance in beef heifers. The experiment was a cross-over design with two treatments and two periods, using eight ruminal cannulated beef heifers. The treatments were a basal diet containing 60% barley silage, 30% barley straw and 10% supplement (DM basis) without (control) or with RFE. The RFE XYL10C was selected specifically for ruminants using a high throughput in vitro micro assay and was sprayed onto the barley straw at a rate of 6.6 × 104 IU/kg DM 24 h before feeding. The diet was prepared daily using a data ranger. Each period was 21 d, with a 14-d adaptation and 7-d sample collection period. The digestibility and nitrogen balance were measured by total fecal and urine collection. Data were analyzed using the PROC MIXED procedure of SAS with fixed effects of treatment, and random effects of period and heifer. Feed intake (8.9 kg/d) and total tract digestibility of DM (65.5%), NDF (57.2%) and ADF (51.2%) were not affected by RFE. Ruminal pH including mean (6.52), minimum (5.79), maximum (7.05), and duration of pH &amp;lt; 5.8 (0.64, h/d) did not differ between treatments. No treatment effects were observed for total VFA concentration (106 mM), molar proportion of acetate (68.2%) and propionate (17.5%) and acetate to propionate ratio (3.94). However, adding RFE vs. control tended (P &amp;lt; 0.08) to increase ruminal NH3-N concentration (5.75 vs. 5.23 mM) and endoglucanase activity (44.3 vs. 40.7 µmol glucose/min/mL wet rumen contents). There were no differences in nitrogen utilization and rumen microbial protein synthesis (90.7 g/d) between treatments. The results indicate that RFE XYL10C did not improve fiber digestion in heifers fed a high forage diet.

265 Determination of microbial enzyme efficacy on fiber digestion of bermudagrass hay supplemented with either DDGS or corn

Abstract Certain enzymes have improved fiber digestion of low-quality forages. Our objective was to determine the efficacy of a combination of a protease and Aspergillus oryzae and A. niger fermentation extracts on fiber digestion and rumen fermentation of bermudagrass hay supplemented with different energy concentrates. Bermudagrass hay was chopped and offered for ad libitum consumption to 20 ewes per study (33.1 ± 10.65 kg BW; Exp. 1; 36.0 ± 11.10 kg BW; Exp. 2) housed individually in 1 × 1.5-m pens (n = 5/trt). In Exp. 1, hay supplemented with DDGS at 0.25% BW, 1% BW, 1% BW + 2.3 g enzyme, or 1% BW + 3.5 g enzyme. In Exp. 2, hay was supplemented with cracked corn at the same levels as used in Exp. 1. Each experiment consisted of a 14-d dietary adaptation followed by 7 d of total fecal collection. On d 21, rumen samples were taken at 3 h intervals from each ewe for analysis of pH and VFA concentrations. Data were analyzed using PROC MIXED of SAS and orthogonal contrasts compared 0.25% vs. 1% BW, no enzyme vs. 2.3 g/d enzyme and 2.3 g/d vs. 3.5 g/d enzyme. In Exp. 1 NDF digestibility was greater (P &amp;lt; 0.05) from 1% vs. 0.25% BW supplement. Ruminal acetate and the acetate:propionate ratio were greatest (P &amp;lt; 0.05) from 0.25% BW vs. the other diets. Exp. 2, DM and OM intake were greater (P &amp;lt; 0.05) from the 1% BW diets and tended (P = 0.08) to be greater from 1% BW alone vs. 1% BW + 2.3 g enzyme. Ruminal acetate concentrations were greatest (P &amp;lt; 0.05) from 0.25% BW. Therefore, the blend of A. oryzae and A. niger fermentation extracts and a protease was not effective under the conditions of this study.

Effects of a recombinant fibrolytic enzyme on fiber digestion, ruminal fermentation, nitrogen balance, and total tract digestibility of heifers fed a high forage diet1.

A metabolism study was conducted using 8 ruminal cannulated beef heifers to investigate the effects of a recombinant fibrolytic enzyme (RFE; xylanase XYL10C) selected specifically for forage-fed ruminants on ruminal pH, fermentation, nitrogen balance, and total tract digestibility of heifers. The experiment was a cross-over design with 2 treatments and 2 periods. The 2 treatments were a basal diet containing 60% barley silage, 30% barley straw, and 10% supplement (DM basis) without (control) or with RFE. The enzyme was sprayed onto the barley straw at a rate of 6.6 × 104 IU·kg-1 DM 24 h before feeding. Each period comprised 2 wk of diet adaptation and 1 wk of sampling and data collection. Feed intake and total tract digestibility of DM, OM, NDF, and ADF were unaffected by RFE. Ruminal pH including mean, minimum, maximum, and duration pH <5.8, did not differ between treatments. Total VFA concentration, molar proportion of individual VFA, and acetate-to-propionate ratio were also not affected by RFE. However, ruminal NH3-N concentration (P < 0.06) and endoglucanase activity (P < 0.08) in ruminal fluid tended to be higher with RFE. Nitrogen utilization and microbial protein synthesis were not affected by treatment. These results indicate that XYL10C did not improve fiber digestion in heifers fed a high forage diet, despite the fact that it was specifically selected for this trait in laboratory assays. However, the increased ruminal NH3-N concentration suggests it potentially increased ruminal proteolytic activity.

Nutrient digestibility and ruminal parameters of cattle fed dried brewers grains and Saccharomyces cerevisiae

The objective of this study was to evaluate the effect of Saccharomyces cerevisiae on nutrient intake and digestibility, the protozoan population and ruminal fermentation kinetics of cattle fed diets containing brewers grains. Four ruminally cannulated crossbreed steers were distributed in a 4 × 4 Latin square. The treatments were in a 2 × 2 factorial arrangement: with or without the inclusion of brewers grains x with or without the addition of S. cerevisiae. Dried brewers grains were included at 11.7% of the dry matter (DM) of the diet. Yeast (S. cerevisiae CNCM I-1077 containing 1.0 × 109 CFU/g) was supplied at 15 g/day. The use of brewers grains and the addition of yeast did not influence the ingestion of DM, crude protein, neutral detergent fiber or total digestible nutrients. Steers fed with brewers grains ingested lower concentrations of non-fibrous carbohydrates (NFC) (P < 0.01). The addition of yeast did not alter DM or nutrient digestibility, but the inclusion of brewers grains reduced DM (P < 0.05) and NFC digestibility (P < 0.01). The use of brewers grains reduced the protozoa populations of the genera Entodinium (P < 0.05) and Isotricha (P < 0.01). Ruminal pH values were not influenced by brewers grains or yeast. There was an interaction between time and the inclusion of brewers grains (P < 0.05) for ammoniacal nitrogen, wherein two hours after feeding, cattle that consumed this by-product had lower concentrations of ammoniacal nitrogen, compared to those that did not consume brewers grains. The addition of live yeast did not influence the proportion of volatile fatty acids (VFA) or total VFA concentration, but the inclusion of brewers grains reduced the VFA concentration and the percentage of isovalerate (P < 0.05). Thus, the use of S. cerevisiae in the bovine diet did not improve fiber digestibility or ruminal fermentation parameters, and the inclusion of 11.7% dried brewers grains did not compromise the total digestible nutrient intake, ruminal pH or the concentrations of acetate, propionate and butyrate.

Effects of urea plus nitrate pretreated rice straw and corn oil supplementation on fiber digestibility, nitrogen balance, rumen fermentation, microbiota and methane emissions in goats

BackgroundUrea pretreatment is an efficient strategy to improve fiber digestibility of low quality roughages for ruminants. Nitrate and oil are usually used to inhibit enteric methane (CH4) emissions from ruminants. The objective of this study was to examine the combined effects of urea plus nitrate pretreated rice straw and corn oil supplementation to the diet on nutrient digestibility, nitrogen (N) balance, CH4 emissions, ruminal fermentation characteristics and microbiota in goats. Nine female goats were used in a triple 3 × 3 Latin Square design (27 d periods). The treatments were: control (untreated rice straw, no added corn oil), rice straw pretreated with urea and nitrate (34 and 4.7 g/kg of rice straw on a dry matter [DM] basis, respectively, UN), and UN diet supplemented with corn oil (15 g/kg soybean and 15 g/kg corn were replaced by 30 g/kg corn oil, DM basis, UNCO).ResultsCompared with control, UN increased neutral detergent fiber (NDF) digestibility (P < 0.001) and copies of protozoa (P < 0.001) and R. albus (P < 0.05) in the rumen, but decreased N retention (−21.2%, P < 0.001), dissolved hydrogen concentration (−22.8%, P < 0.001), molar proportion of butyrate (−18.2%, P < 0.05), (acetate + butyrate) to propionate ratio (P < 0.05) and enteric CH4 emissions (−10.2%, P < 0.05). In comparison with UN, UNCO increased N retention (+34.9%, P < 0.001) and decreased copies of protozoa (P < 0.001) and methanogens (P < 0.001). Compared with control, UNCO increased NDF digestibility (+8.3%, P < 0.001), reduced ruminal dissolved CH4 concentration (−24.4%, P < 0.001) and enteric CH4 emissions (−12.6%, P < 0.05).ConclusionsA combination of rice straw pretreated with urea plus nitrate and corn oil supplementation of the diet improved fiber digestibility and lowered enteric CH4 emissions without negative effects on N retention. These strategies improved the utilization of rice straw by goats.