Neutral Detergent Fiber Degradability Research Articles

Effect of Partial or Complete Replacement of Dietary Inorganic Trace Minerals Supplement with an Advanced Chelated Source on Nutrient Digestibility in Sheep

The delicate balance of trace mineral supplementation is critical for optimizing rumen function and overall ruminant health. This study evaluated the solubility of an advanced chelate technology-based supplement and assessed its impact on rumen degradability and apparent total tract digestibility (ATTD) when replacing inorganic sources. The solubility of the advanced trace minerals supplement (ACTM) was assessed at pH 5 and pH 2. In situ ruminal degradability of dry matter (DM), organic matter (OM), and fiber fractions was evaluated using two fistulated rams fed diets supplemented with either ACTM or inorganic trace minerals. ATTD was determined in 6 lambs fed diets supplemented with 100% ACTM, 50% ACTM, and 50% inorganic (50% ACTM), or 100% inorganic sources in a Latin square design. Results showed solubilities ranging from 6.75% to 11.81% at pH 5, increasing to 69.24% to 80.47% at pH 2. ACTM supplementation significantly enhanced the rumen degradability of neutral detergent fiber (NDF) and acid detergent fiber (ADF) at 6 h of incubation (p ≤ 0.05). The 100% ACTM treatment significantly decreased rumen pH (p = 0.051) and improved DM, OM, NDF, and ADF digestibility, as well as trace mineral absorbability compared to 100% inorganic (p ≤ 0.05). These findings highlight the potential of ACTM supplementation to enhance ruminal degradability, promote better trace mineral absorption, and improve the ATTD of nutrients compared to inorganic sources.

Impact of Inoculation with Pediococcus pentosaceus in Combination with Chitinase on Bale Core Temperature, Nutrient Composition, Microbial Ecology, and Ruminal Digestion of High-Moisture Alfalfa Hay

This study evaluated the effects of Pediococcus pentosaceus (PP) and chitinase combinations on the conservation and nutritive value of alfalfa high-moisture hay (HMH). P. pentosaceus [1012 colony forming unit/g fresh forage] combined with (g/tonne of fresh forage) 1.5 (PP + LC), 7.5 (PP + MC), or 15.0 (PP + HC) g of LANiHay01 chitinase (Exp. 1) or with LANiHay02 (PP + Fe; 1.5 g), LANiHay01 (PP + Pe; 1.5 g), or Sigma (PP + Si; 55 mg) chitinase/tonne (Exp. 2) were used in 2016. In 2017, PP was applied alone or in combination with LANiHay01 at 1.5 g (PP + LC) or 7.5 g (PP + MC) chitinase/tonne (Exp. 3 and 4). Deionized water and propionic acid (4.0 L/tonne of fresh forage in Exp. 1 and 2 and at 6.0 L/tonne of fresh forage in Exp. 3 and 4) were applied as neutral (CON) and positive control (CON+), respectively. The maximum temperature (r2 = 0.66) and NH3-N concentration (r2 = 0.80) of the HMH were positively related to total microbial populations. PP + MC had lower (p ≤ 0.05) yeast and mold counts than CON in Exp. 3 and 4 while the neutral detergent fiber degradability was greater (p < 0.01) for PP + MC and PP + LC than CON in Exp. 1 and 3, respectively. P. pentosaceus in combination with chitinase has the potential in conserving the nutrient quality of alfalfa HMH.

PSIV-28 Determination of the extent and rate of nutrient degradation of potato and other byproducts by rumen microorganisms in vitro

Abstract Byproducts in livestock diets have the potential to reduce the environmental impact of food production and the cost of animal feeding. The objective was to evaluate the extent and rate of nutrient degradability of potato and other byproducts by rumen microorganisms in vitro. Byproducts included barley malt sprouts, fries, dry peel, and hopper, which were supplied by Performix Nutrition Solutions (Nampa, ID). Two in vitro incubators (DAISYII, ANKOM Technology) each with four incubation jars were used to evaluate ruminal degradability of dry matter (DM) and neutral detergent fiber (NDF). Each jar contained 1,600 mL buffer solution (ANKOM Technology), 400 mL rumen contents (collected from two ruminally cannulated cows), 14 filter bags (F57, ANKOM Technology) with 0.5 g of ground byproduct, 14 filter bags with 0.5 g of ground corn (standard), and 14 blank bags. Each jar was purged with CO2 and filter bags were incubated at 39°C for 0, 3, 6, 9, 12, 24, and 48 h, then removed, rinsed, dried at 55˚C for 48 h, weighed, and analyzed for DM and NDF. Each byproduct was incubated in 3 jars on two different d (6 replicates). Degradation of DM was separated into fractions A (disappearance at 0 h), C (DM remaining after 48 h) and B (100%-A-C). Rate of degradation for fraction B was the slope of the natural logarithms of the DM disappearance. All byproducts were compared with standard corn grain as the control. Fraction A for DM was not different (P > 0.40) for barley malt sprouts (35.4%) and hopper (33.7%), and less (P < 0.05) for dry peel (27.8%) and fries (13.2%) when compared with corn grain (33.4%). Fraction B for DM was greater (P < 0.05) for fries (74.0%), not different (P = 0.44) for hopper (56.1%), and less (P < 0.05) for dry peel (43.6%) and sprouts (37.0%) when compared with corn grain (53.9%). Rate of DM degradation for fraction B was greater (P < 0.05) for fries (9.9%/h) and hopper (7.0%/h), and not different (P > 0.16) for dry peel (4.6%/h) and sprouts (3.0%/h) when compared with corn grain (3.8%/h). Fraction C for DM was greater (P < 0.05) for dry peel (28.6%) and sprouts (27.6%), and not different (P = 0.20) for fries (12.9%) and hopper (10.3%) when compared with corn grain (12.7%). The indigestible fraction of NDF after 48 h of incubation was greatest for dry peel (58.5%), intermediate for sprouts (40.1%) and hopper (36.7%), and least for fries (25.4%; P < 0.05). These results demonstrate that the extent and rate of ruminal DM degradability of various potato and other byproducts differ and may be more or less degradable in the rumen compared with corn grain.

Lemongrass essential oil in silage and as a feed additive has limited effect on animals feed intake and rumen fermentation

ABSTRACT This study aimed to evaluate the effects of lemongrass essential oil (LEO) addition during the ensiling and subsequent sheep feed intake, particle selection, in vitro rumen fermentation, total-tract apparent digestibility and nitrogen balance. Eight Dorper lambs 19.4±2.40 (mean±SD) kg of body weight were used in a trial using a 4 × 4 Latin Square design to evaluate: I. LEO addition during the whole-plant sorghum ensiling: 0 (EN−) and 4 (EN+) mL per kg of sorghum dry matter (DM); and II. LEO supply during the animals feeding: 0 (F−) and 1.6 (F+) mL per kg of diet DM. Treatments showed no effect on feed intake and particle size selection. Ensiling with LEO increased ammonia-N when LEO was not added during incubation. LEO addition during incubation decreased neutral detergent fibre (NDF) degradation when LEO was not added during the ensiling. In addition, LEO addition increased fermentation gas production and decreased digestibility. LEO addition in sheep feeding tended to decrease crude protein digestibility. Treatments did not affect nitrogen balance and the average daily gain. Thus, LEO supply during ensiling and sheep feeding does not affect feed intake, particle selection and nitrogen balance.

Effect of exogenous cellulase pretreatment of straw-type fermented total mixed ration on digestibility and ruminal fermentation in growing beef cattle.

This study aimed to assess the impact of corn straw-based unfermented and fermented total mixed rations (TMR) supplemented with exogenous cellulase on the in vitro fermentation characteristics, growth performance, feeding behavior, apparent digestibility, rumen fermentation and digestive enzyme activities of Chinese Simmental bulls. Unfermented (direct spraying of exogenous cellulase onto TMR, TMR) and fermented (exogenous cellulase fermentation for more than 7 d, fermented total mixed rations [FTMR]) TMR were collected, dried, powdered and used as fermentation substrates. The fermentation liquid was ruminal fluid collected from Chinese Simmental bulls. The artificial rumen culture fluid were continuously cultured in vitro for 48 h. Based on the diets they were fed, 24 healthy Chinese Simmental bulls (average weight of 495.93 ±10.89 kg) were randomly divided into two groups, with 12 bulls in each group, which were fed TMR or FTMR. The study lasted 56 d. In in vitro experiments, the neutral detergent fiber degradability and total volatile fatty acid, propionate, iso-butyrate, iso-valerate and valerate concentrations were greater in the FTMR group (p<0.05) than in the TMR group. However, the methane production, pH and A/P of the FTMR group tended to be lower (p<0.05) than those of the TMR group. In the in vivo experiments, the average daily gain, eating rate, and feed efficiency of the FTMR groups were greater (p<0.05) than those of the TMR group. Similarly, the NDF degradability of the FTMR group was greater (p<0.05) than that of the TMR group. Compared to those in the TMR group, the concentrations of total volatile fatty acids, iso-butyrate, propionate and butyrate were greater in the FTMR group (p<0.05), and the A/P ratio was lower (p<0.05). Similarly, cellulase, xylanase, and β-glucosidase activities were greater (p<0.05) in the FTMR group than in the TMR group. Corn straw-based fermented total mixed rations supplemented with exogenous cellulase play a vital role in decreasing the structural carbohydrate content of TMR and ruminal methane production in vitro, improving nutrient digestion and absorption, optimizing rumen fermentation, and improving the growth performance of beef cattle.

Crude Glycerol Increases Neutral Detergent Fiber Degradability and Modulates Rumen Fermentative Dynamics of Kikuyu Grass in Non-Lactating Holstein Cows Raised in Tropical Conditions

Crude Glycerol Increases Neutral Detergent Fiber Degradability and Modulates Rumen Fermentative Dynamics of Kikuyu Grass in Non-Lactating Holstein Cows Raised in Tropical Conditions

Estimation of Fiber Fragility and Digestibility of Corn Silages and Cool Season Pastures

Fiber fragility is defined as the particle size reduction rate during chewing and can help to explain the effects on feed intake and animal performance of different fiber sources. This study aimed to estimate the fiber fragility of corn silage and cool-season pasture based on their chemical composition. Between June and December 2022, 25 samples of corn silage and 25 samples of cool-season pasture were collected from dairy farms in the state of Rio Grande do Sul. The samples were analyzed for particle size distribution, chemical composition, and fiber fragility. Contents of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and fiber fragility were greater in corn silages compared to cool-season pasture. However, the ADF–NDF ratio was similar in forages. Crude protein (CP) content and the in situ degradation of DM and NDF were greater in cool-season pasture than corn silage. Dry matter and NDF in situ degradation were negatively correlated with increased contents of ADF, NDF, and ADL and the ADF–NDF ratio in forages. Fiber fragility was negatively correlated with DM degradation and positively correlated with contents of ADF, NDF, ADL, and DM. Fiber fragility decreased as CP content increased. Thus, greater fiber fragility may jeopardize nutrient degradation, and levels of fiber fragility are directly associated with fiber content.

Ruminal passage rate and digestibility of fiber from dairy cows consuming diets containing alfalfa and orchardgrass hays with different concentrations of undegradable neutral detergent fiber (uNDF)

This study aimed to evaluate the effect of feeding diets with different fractions of undegraded NDF (uNDF) and potentially degradable (pdNDF) on ruminal NDF degradation and passage kinetics of lactating dairy cows. Six rumen-cannulated (533 ± 43 kg BW and 122 ± 15 DIM) and 6 non-cannulated (558 ± 62 kg BW and 126 ± 16 DIM) primiparous Holstein dairy cows were randomly assigned to 1 of 2 experimental diets in a crossover design with 2 28-d periods. The experimental diets were formulated to include either alfalfa hay (ALFA) or orchardgrass hay (ORCH) in addition to corn silage. Rations were formulated to contain 30% NDF (DM basis), where the concentrate, corn silage, and each of the hays provided one third of the dietary NDF. The marker dilution technique was used to measure the passage rate utilizing a pulse dose of marked corn silage fiber. On d 17 and 24 of each period, ruminal contents were evacuated to determine ruminal pool size. Following the return of the ruminal contents containing the pulse dose of marked corn silage to the rumen, ruminal grab samples were collected at 0, 3, 6, 9, 12, 24, 36, 48, 60, and 72 h. Samples from each time point were separated into solids and liquid, and the solids were analyzed for NDF, uNDF, and marker concentration. Alfalfa hay had a higher concentration of CP (16.4 vs. 10.7%) and a lower concentration of NDF (38.0 vs. 63.2) than orchardgrass hay. Alfalfa hay had a greater concentration of uNDF than orchardgrass hay (36.5 vs. 32.8% uNDF; NDF basis). Cows consuming the ALFA diet had similar milk yield (39.1 kg/d) and similar milk fat and protein concentrations (3.72% fat and 3.24% protein, respectively) than cows consuming the ORCH diet. Cows consuming the ALFA diet consumed more DM (26.7 vs. 24.6 kg/d) and uNDF (2.7 vs. 2.3 kg/d), than cows consuming the ORCH diet. Cows consuming the ALFA diet digested more NDF and pdNDF than cows consuming the ORCH diet (3.3 vs. 2.8 kg/d). Even though cows consuming the ALFA diet had a smaller pool size of NDF than cows consuming the ORCH diet (5.4 vs. 6.7 kg), the pool size of uNDF did not differ between groups (2.4 kg). Cows consuming the ALFA diet had a faster rate of passage of uNDF than cows consuming the ORCH diet (5.02 vs. 4.03%/h). This translated into a shorter mean retention time of uNDF for cows consuming the ALFA diet relative to cows consuming the ORCH diet (21.0 vs. 26.2 h). In conclusion, cows consuming diets containing alfalfa hay had a faster ruminal passage rate and a shorter mean retention time of uNDF than cows consuming diets containing orchardgrass hay, and this occurred despite the greater concentrations of dietary uNDF in the alfalfa-based diet. These findings suggest that the kinetics of ruminal digestion and passage influence NDF degradation in ways beyond uNDF concentration or forage quality.

SF6 Tracer Technique to Estimate Methane Emission in a Dual-Flow Continuous Culture System: Test and Application

This study aimed to evaluate the sulfur hexafluoride (SF6) tracer technique for estimating methane (CH4) emissions in dual-flow continuous culture systems (DFCCS). In experiment 1 (Exp1), fermenters were filled with water, and known CH4 concentrations (0, 1.35, 2.93, or 4.43 g/d) were injected using permeation tubes with SF6 release rates (3.30 or 9.65 mg/d). Headspace gas was collected using canisters, and the SF6 technique estimated CH4 recovery. Experiment 2 (Exp2) involved a DFCCS fermentation trial with ruminal fluid from three Holstein cows, testing diets with soybean meal or its partial replacement (50%) by Chlorella or Spirulina. Headspace gas was collected at intervals post-feeding. Standard curves for SF6 and CH4 quantification were inadequate for DFCCS samples, with the CH4:SF6 ratio differing from standards, indicating the data needs further SF6 release rate evaluation. In Exp1, a high correlation (r = 0.97) was found between infused and calculated CH4, indicating good repeatability. Low and high SF6 rates performed similarly at low CH4 infusion, but high SF6 overestimated CH4 at high infusion. Exp2 showed CH4 emissions irrespective of SF6 rate and indicated reduced CH4 emissions and increased NDF degradation with algae-containing diets. Further evaluation of the SF6 tracer technique is warranted for DFCCS.

First Evidence of the Effects of Polyethylene Terephthalate Microplastics on Ruminal Degradability and Gastro-Intestinal Digestibility of Mixed Hay.

Microplastics (MPs) raise environmental concerns. However, their effects on the ruminal-gastro-intestinal system have not yet been studied. This study aims to investigate the effects of polyethylene terephthalate (PET) MPs on the ability of the ruminal-gastro-intestinal system to degrade and digest mixed hay. Using a three-step in vitro ruminal-gastro-intestinal incubation system, PET MPs were introduced at concentrations of 0, 5, 10, and 15 g/L in ruminal and gastro-intestinal solutions. Ruminal fluid was collected from three 16-month-old Piedmontese bulls. The experiment was conducted on three mixed hays and was repeated three times, with triplicate incubations in each run. The results reveal that PET MPs reduced the degradability and digestibility of crude protein. Specifically, crude protein degradation was reduced by 9% at medium and 16% at high PET MP concentrations in the ruminal phase, while the crude protein digestibility of undegraded crude protein was reduced by 8% at the lowest PET MPs concentration in the gastro-intestinal tract. Additionally, PET MPs reduced the degradation of neutral detergent fiber at medium and high PET MP concentrations in the ruminal phase by 9% and 13%, respectively. These results highlight the risks of PET MPs contamination on ruminal-gastro-intestinal functions and underscore the urgent need to mitigate MPs contamination in the livestock sector.

Lupin Seed Supplementation as a Functional Feed Additive: In Vitro Ruminal Gas, Methane and Carbon Dioxide Production, Fermentation Kinetics, and Nutrient Degradability.

The inevitable enteric gas emission from ruminants is considered a modern-day problem from an environmental perspective. Addressing this problem requires nutritional approaches such as the use of phytogenic additives in ruminant diets. In this regard, lupin seed (LS) can be a useful additive due to its phytochemical constituents. Therefore, this study investigated the effects of lupin (Lupinus angustifolius) seed supplementation as a functional and sustainable feed additive in sheep diet (50:50 concentrate-to-forage ratio) on in vitro gas production (GP; mL/g DM), methane (CH4; mL/g DM) and carbon dioxide (CO2; mL/g DM) emissions, fermentation parameters, and nutrient degradability (g/kg DM incubated). Gas production and CH4 were measured per gram of incubated dry matter (DM), degradable DM (dDM), degradable neutral detergent fiber (dNDF), and degradable acid detergent fiber (dADF). Lupin seeds were included at 0 (control), 0.5, 1.0, 1.5, and 2% of the diet. The seeds contained 3.27% essential oils (DM basis), with eucalyptol as the main phytochemical. The highest GP per gram of DM and dDM was observed (p < 0.01) with 2.0% LS supplementation level. While 1.0% LS had the highest GP per gram of dNDF, 0.5% lupin diet had the highest GP per gram of dADF. Asymptotic GP and CH4 emissions linearly and quadratically increased (p < 0.01) with increasing LS level, while lag time decreased. Despite increased CH4 production, the proportion of CH4 in total biogas was lower (p = 0.008) for LS treatments than the control, with the 0.5% LS showing the lowest CH4 proportion. Production of CO2 increased with lupin seed treatments, with 0.5% LS producing the highest proportion (p = 0.027). Degradability of DM, NDF, and ADF was greater (p < 0.01) for the high LS supplementation level, while 0.5% supplementation level decreased ADF degradability. Total short-chain fatty acids, acetic acid, and propionic acid increased (p < 0.05) with LS supplementation level, leading to a reduced acetate:propionate ratio. Rumen pH decreased (p = 0.036) with LS supplementation, while ammonia-N decreased (p = 0.045) and estimated metabolizable energy increased (p < 0.001) linearly. Calculated microbial protein synthesis (p = 0.005) and gas yield (p = 0.047) increased with LS supplementation level. LS supplementation at 2.0% of diet (DM basis) increased GP and CH4 emission (mL/g DM) and enhanced nutrient degradability, suggesting its potential use as a functional feed additive for ruminants when supplemented at a 2.0% level into diet.

Effects of Centella asiatica Extracts on Rumen In Vitro Fermentation Characteristics and Digestibility.

Two in vitro experiments were conducted to evaluate the effects of Centella asiatica extract (CAE) supplementation on the rumen's in vitro fermentation characteristics. In the first experiment, CAE with five concentrations (C: 0%; T1: 3.05%; T2: 6.1%; T3: 12.2%; and T4: 24.4% CAE in diet) was supplemented in the rumen fluid and incubated for 6, 24, and 48 h to determine the optimal dosage. The total gas and methane production increased in all incubation times, and the total volatile fatty acids increased at 6 and 48 h. Ammonia nitrogen, branched chain volatile fatty acids, acetate, and butyrate were increased by CAE supplementation. T1 was chosen as the optimal dosage based on the total volatile fatty acids, branched chain volatile fatty acids, and ammonia nitrogen production. The CAE with the identified optimal dosage (T1) was incubated to identify its effect on the rumen's in vitro degradability in the second experiment. The CAE supplementation did not influence the in vitro dry matter, crude protein, or neutral detergent fiber degradability. In conclusion, CAE has no CH4 abatement or digestion promotion effects. However, CAE could be utilized as a feed additive to increase the rumen's total volatile fatty acid production without an adverse effect on the in vitro dry matter, crude protein, or neutral detergent fiber degradability.

Prolonged feeding of high-concentrate diet remodels the hindgut microbiome and modulates nutrient degradation in the rumen and the total gastrointestinal tract of cows

The aims of this research were to evaluate how prolonged feeding of a high-concentrate diet affects the ruminal degradation kinetics of fiber and starch, and to evaluate the effects of the high-concentrate diet on apparent total-tract nutrient digestibility in dairy cows. We also investigated the dysbiotic effects and the remodeling of the hindgut microbiome with prolonged high-concentrate feeding. Nine Holstein cows were used in 2 experimental periods; in each period, cows were first fed a 100% forage diet for 1 wk, followed by stepwise adaptation during one week to a high-concentrate (HC) diet (65% concentrate), which was then fed for 4 consecutive weeks. The kinetics of in situ ruminal degradability of grass silage (DM and NDF), corn grain and wheat grain (DM and starch), as well as the apparent total-tract nutrient digestibility were evaluated in the forage feeding and in wk 4 on the HC diet. Whereas the hindgut microbiome and fermentation profile were evaluated on a weekly basis. Regarding the in situ ruminal degradability due to grain type, the rate of degradation of the potentially degradable fraction and the effective rumen degradability of wheat grain were greater compared with corn grain. The in situ ruminal degradability of NDF decreased with the HC diet. However, the apparent total-tract digestibility of CP, fat, starch, NDF, ADF, and NFC increased with the HC diet compared with forage feeding. In addition, the HC diet increased the concentration of short-chain fatty acids in the hindgut, lowering fecal pH by 0.6 units, which correlated positively with microbial α diversity. This resulted in lower α diversity with the HC diet; however, α diversity (number of amplicon sequence variants) showed recovery in wk 3 and 4 on HC; in addition, microbial β diversity did not change from wk 2 onward on the HC diet. Two microbial enterotypes were identified: one for the forage diet with abundance of Akkermansia and Anaerosporobacter, and another enterotype for the HC diet with enrichment in Bifidobacterium and Butyrivibrio. Overall, results show that major microbial shifts and hindgut dysbiosis occurred in wk 1 on the HC diet. However, the hindgut microbial diversity of cows adapted after 3 wk of consuming the starch-rich ration. Thus, feeding the HC diet impaired fiber degradation in the rumen, but increased apparent total-tract nutrient digestibility. Likely, the forage diet contained less digestible NDF than the HC diet due to greater inclusion of forages with lower NDF digestibility and lower inclusion of more digestible nonforage NDF. Results also suggest that the adaptation of the hindgut microbial diversity of cows observed 3 weeks after the diet transition likely contributed to enhance total-tract nutrient digestibility.

Influence of maize genotypes and harvest stages on in-silo fermentation quality and nutritional value of corn silage during hot summer condition of the tropics

The aim of the experiment was to evaluate the potential of promising summer maize genotypes and optimal stage of harvesting these genotypes for ensiling in terms of dry matter (DM), starch, and crude protein (CP) yields, silage fermentation quality, nutrients profile, total digestible nutrients, metabolizable energy (ME) content, Cornell Net Carbohydrate and Protein System (CNCPS) carbohydrate (CHO) subfractions composition, in vitro DM digestibility (DMD) and in situ starch degradation characteristics. Six maize genotypes were chosen for the study: DK9108 from Monsanto, P30Y87, P3939 from Pioneer, QPM-300 (quality protein maize) and W94 from the International Maize and Wheat Improvement Center (CIMMYT), and a local cultivar, Afgoii, from the Cereal Research Institute (Persabaq, KP). A total of 72 plots (8 m × 10 m) were blocked in three replicate fields, and within each field, each genotype was sown in four replicate plots according to a randomized complete block design. For the data analysis, the Proc-Mixed procedure of Statistical Analysis System with repeated measure analysis of variance was used. The DM yield was strongly influenced (P < 0.001) by maize genotypes, varying from 12.6 to 17.0 tons/ha. Except for total CHO and ammonia nitrogen (NH3-N), the contents of all measured chemical components varied (P < 0.001) among the genotypes. Further comparison revealed that, genotype P3939 had a higher (P < 0.05) content of CP (7.27 vs. 6.92%), starch (36.7 vs. 27.9%), DMD (65.4 vs. 60.0%), ME (2.51 vs. 2.30 Mcal/kg) and lactic acid (5.32 vs. 4.83%) and lowest content of NDF (37.3 vs. 43.1%), pH (3.7 vs. 4.10) compared to the local cultivar (Afgoii). Advancement of post-flowering maturity from 25 to 35% DM (23 to 41 days after flowering (DAF)) increased (P < 0.05) the DM yield (10.4 to 17.8 tons/ha), starch content (29.1 to 35.0%), DMD (65.3 to 67.3%) and ME (2.34 to 2.47 Mcal/kg), and decreased (P < 0.001) the contents of CP (7.42–6.73%), NDF (48.8–38.5%), pH (4.10 to 3.60), NH3-N (8.93–7.80%N) and effective degradability of starch (95.4 to 89.4). Results showed that for higher yields and silage nutritional and fermentation quality, maize crops should be harvested at whole crop DM content of 30–35% (34 to 41 DAF). It was further concluded that genotype P3939 is the most suitable summer maize genotype for silage production in terms of yields and silage nutritional and fermentation quality under the hot environmental conditions of the tropics.

Efeito de um aditivo fúngico multiespécie no perfil de fermentação ruminal, de-gradabilidade e cinética de produção de gases

Two experiments evaluated the effect of a multispecies fungal complex (BP, BIOPREMIX MX®, Ruminal Fermentation Tech, Uruguay). In Experiment 1 (E1), the impact of adding BP to a total mixed ration (TMR) on ruminal fermentation profile and TMR in situ degradation kinetics was assessed. In Experiment 2 (E2), the effect of adding BP to various substrates on in vitro fermentability was examined. In E1, 4 Holstein cows with rumen cannulas were randomly assigned to Control (TMR with forage:concentrate ratio 75:25) or Control + 120 g/cow/d of BP (BP) and received ad libitum TMR for 30 days. Samples of TMR were ruminally incubated to estimate in situ degradation kinetic. Ruminal pH, ammonia, and volatile fatty acids (VFA) concentrations were measured just before feeding, 4 h and 8 h post feeding. In E2, a factorial arrangement included two BP levels (0 -Control or 6.5 g BP per kg dry matter incubated-WBP) and 8 substrates. In vitro gas production kinetics (GPk), dry matter digestibility (IVDMD), methanogenic potential (CH4), partitioning factor (PF), VFA, and microbial crude protein (MCP) were estimated. The BP increased proportion of propionate (P ≤ 0.05) and reduced ketogenic:glucogenic ratio and Lag phase of NDF (P ≤ 0.05). WBP tended to increase IVDMD, and substrate affected GPk, IVDMD, CH4, PF, VFA and MCP (P ≤ 0.01). Overall, BP improved ruminal metabolism favoring a more glucogenic profile, a shortening Lag phase in NDF degradation, and increasing IVDMD.

Appraisal of Spatial Distribution and Fibre Degradability of Cereal–Legume Fodders to Enhance the Sustainability of Livestock Feed Supply in Sub-Tropics

Fodder scarcity, inadequate nutritional quality, and lack of degradation kinetics research are among the serious concerns hindering sustainable development of livestock globally. Rumen degradation kinetics data on neutral detergent fibre (NDF) in buffaloes are lacking for most tropical forage species. This study evaluated the effect of forage species, family, and growing location on NDF concentration and in situ degradability of six tropical cereal and four legume fodder crops. The fodder crops were grown following uniform recommended agronomic practices at three different agroecological locations and harvested at the appropriate growth stage: cereals at booting and legumes at 50% flowering. Later, the dried ground forage samples were incubated in the four rumen-cannulated Nili-Ravi buffalo cows in a four × two × three split-plot design for 0, 4, 8, 16, 24, 48, 96, and 168 h. The degradation fractions and degradability, expressed either on an NDF or dry matter basis, were considerably affected by forage family (cereal vs. legume) and growing locations and their interaction. Legume fodders degraded more rapidly but to a lesser extent than cereal fodders. The chemical components, notably the NDF, showed a significant but moderate negative relationship with the effective NDF degradability. Among studied fodders, the legumes had a significantly lower NDF concentration and subsequent degradability than the cereals. Although the cereals showed a slower rate of NDF degradation, their overall degradability was higher. The agro-climatic variability among three locations strongly impacted the NDF concentrations and fractions in the tropical forages. Effective NDF degradability was also correlated with the fodders’ NDF concentration, especially in cereals where the nature of the correlation was negative. In conclusion, the nutritional composition and NDF degradation parameters of the fodders were significantly affected by the species, family, and location of growth and their interactions. These results will help to improve agronomy and usage of these important fodder crops.

Novel oxidising feed additives reduce in vitro methane emissions using the rumen simulation technique

Enteric methane (CH4) produced by ruminant livestock is a potent greenhouse gas and represents significant energy loss for the animal. The novel application of oxidising compounds as antimethanogenic agents with future potential to be included in ruminant feeds, was assessed across two separate experiments in this study. Low concentrations of oxidising agents, namely urea hydrogen peroxide (UHP) with and without potassium iodide (KI), and magnesium peroxide (MgO2), were investigated for their effects on CH4 production, total gas production (TGP), volatile fatty acid (VFA) profiles, and nutrient disappearance in vitro using the rumen simulation technique. In both experiments, the in vitro diet consisted of 50:50 grass silage:concentrate on a dry matter basis. Treatment concentrations were based on the amount of oxygen delivered and expressed in terms of fold concentration. In Experiment 1, four treatments were tested (Control, 1× UHP + KI, 1× UHP, and 0.5× UHP + KI), and six treatments were assessed in Experiment 2 (Control, 0.5× UHP + KI, 0.5× UHP, 0.25× UHP + KI, 0.25× UHP, and 0.12× MgO2). All treatments in this study had a reducing effect on CH4 parameters. A dose-dependent reduction of TGP and CH4 parameters was observed, where treatments delivering higher levels of oxygen resulted in greater CH4 suppression. 1× UHP + KI reduced TGP by 28 % (p = 0.611), CH4% by 64 % (p = 0.075) and CH4 mmol/g digestible organic matter by 71 % (p = 0.037). 0.12× MgO2 reduced CH4 volume by 25 % (p > 0.05) without affecting any other parameters. Acetate-to-propionate ratios were reduced by treatments in both experiments (p < 0.01). Molar proportions of acetate and butyrate were reduced, while propionate and valerate were increased in UHP treatments. High concentrations of UHP affected the degradation of neutral detergent fibre in the forage substrate. Future in vitro work should investigate alternative slow-release oxygen sources aimed at prolonging CH4 suppression.

107 Bacterial direct-fed microbial mixtures effects on beef cattle ruminal degradability kinetics

Abstract The effects of bacterial direct-fed microbial (DFM) mixtures on beef cattle ruminal degradability were evaluated. Six ruminally cannulated beef steers (BW = 520 ± 30 kg) were used in a replicated 3 × 3 Latin square design and offered a steam-flaked corn-based finishing diet to ad libitum intake during three, 28-d periods. Treatments were: 1) Control (no DFM, lactose carrier only); 2) Treat-A (L. animalis, P. freudenreichii; B. subtilis; and B. licheniformis), at 1:1:1:3 ratio, respectively; totaling 6 × 109 CFU (50 mg)/animal-daily minimum; and 3) Treat-B, the same DFM combination, but with doses at 1:1:3:1 ratio. Bacterial counts were approximately 30% greater than the minimum expected. Pre-dehydrated (55ºC for 72 h) diets and forage substrates were ground (2 mm) and placed into 10 × 20 cm (28 µm) nylon bags (8 and 5 g, as-is respectively). The diet-substrate included a mixture of (DM basis) steam-flaked corn (70%), alfalfa hay (10%), and wet corn gluten feed (20%). The forage-substrate was represented by ‘WW-B Dahl’ Old World bluestem (Bothriochloa bladhii). Substrate in-situ bags were placed within a nylon mesh (with weights) at the ruminal ventral sac, and reversely removed at 0, 2, 4, 8, 12, 20, 32, 48, 64, 72, and 96 h after feeding. Samples were removed, rinsed, and dehydrated for 72 h at 55oC. Residues were composited within period, steer, incubation-time, corrected for residual moisture and were used to fit a first-order kinetics model using the NLIN procedure of SAS (animal = experimental unit). Steers offered Treat-A tended to show an increase on the rate of degradation of NDF (P = 0.15) and ADF (P = 0.10) fractions; increased (P &amp;lt; 0.01) hemicellulose potentially degradable fraction (B); and increased (P = 0.02) the effective degradable fraction of NDF (tendency for ADF, P = 0.08) at pre-established rate of passages of 4, 5, and 6% of the diet-substrate compared with Control, while tending to have a reduced rate of degradation for the overall DM (P = 0.06) and OM (P = 0.08) fractions. When the in-situ bags containing the forage-substrate were incubated, steers offered Treat-A showed an increased (P &amp;lt; 0.01) lag time (T0) for hemicellulose compared with Control, while those offered Treat-B had a decreased (P = 0.02) hemicellulose potentially degradable fraction (B) compared with Control. The effective degradable fraction for hemicellulose at pre-established rate of passages of 4, 5, and 6% tended (P = 0.09) to numerically increase for steers offered Treat-A compared with Control. The combination of bacteria in Treat-A enhanced the ruminal degradation of high-quality fiber components, as indicated by the improvements observed within the more degradable fractions from ingredients used in the diet and the forage substrates. Further assessment is warranted to investigate post-ruminal nutrient disappearance.

Replacing soybean meal with microalgae biomass in diets with contrasting carbohydrate profiles can reduce in vitro methane production and improve short-chain fatty acid production

The objective of this study was to evaluate the interaction of dietary carbohydrate profile and soybean meal (SBM) replacement with either Chlorella pyrenoidosa (CHL) or Spirulina platensis (SPI) on in vitro fermentation. This experiment was conducted as a randomized complete block design, with fermentation run (3 runs) considered as blocks. The treatments were arranged in a 2 × 5 factorial design, where the first factor was the carbohydrate profile, which was composed of diets containing 42.5% NDF and 26.8% starch (HF-LS) or 26.8% NDF and 40.6% starch (LF-HS) and the second factor was the protein source, in which a control diet (100% SBM), partial replacement of SBM with CHL (1/2 CHL) or SPI (1/2 SPI), or total replacement of SBM with CHL or SPI were used. All experimental diets were formulated to have 17% crude protein. The ruminal fluid was collected from 2 lactating Holstein cows, buffered with Van Soest medium at a ratio of 1:2 and added to serum bottles containing 0.50 g of the experimental diets. Bottles were incubated at 39°C for 24 and 48 h in triplicate; headspace pressure was measured, along with gas collection for methane (CH4) quantification at 0, 2, 4, 8, 16, 24, 36, and 48 h after incubation. The final medium was used to measure pH, ammonia, and volatile-fatty acid (VFA). After incubation, feed bags were recovered and used for estimation of degradability of DMD, NDF, and OMD. Statistical analysis was carried out using the MIXED procedure of SAS, with carbohydrate profile, protein source, assay, and its interactions as fixed effects, with run and bottle as random effects. Orthogonal contrasts were used to compare carbohydrate profile, algae species, carbohydrate profile × algae interaction, and linear and quadratic effects of SBM replacement with CHL or SPI. There was no interaction effect between carbohydrate profile and algae source. LF-HS improved gas production, degradability of nutrients, and VFA, mainly increasing the production of butyrate and propionate. When compared with CHL, SPI had a greater degradability of nutrients and branched VFA, along with reduction in total gas production and tended to reduce total CH4 yield. The replacement of SBM with algae linearly reduced the degradability of nutrients, along with a linear reduction in gas production. When replacement of SBM with only SPI was evaluated, SPI slightly reduced the degradability of nutrients; however, it promoted a linear reduction in CH4 yield, as well as reduction in CH4 yield by unit of degraded DM, NDF, and OM. In summary, there was no interaction of carbohydrate profile and protein source, which means that SBM replacement had a similar effect, regardless of dietary carbohydrate profile. Spirulina may be a more suitable algae source when compared with Chlorella due to the potential to reduce CH4.

&lt;i&gt;In situ&lt;/i&gt; and &lt;i&gt;in vitro&lt;/i&gt; degradation parameters of elephant grass silage with sugarcane bagasse

The objective of this study was to evaluate the chemical composition and in situ degradability of elephant grass silage dry matter with increasing levels of sugarcane bagasse. A completely randomized design was adopted with five treatments: 0, 5, 10, 15, and 20% inclusion of sugarcane bagasse on an as-fed matter basis, with five replications, totalling 25 experimental units. The increasing proportion of sugarcane bagasse analysed was favourable only in increasing the concentration of dry matter and fibre of silages and in maintaining a considerable crude protein content. In the in situ degradation assay, the addition of sugarcane bagasse in silage decreased the ruminal degradability of dry matter, and as the passage rates increased, the effective degradability decreased. In the in vitro gas production assay, the total production of gases was decreased with the inclusion of sugarcane bagasse, as did the degradability of organic matter and neutral detergent fibre. The recommendation for the inclusion of sugarcane bagasse should be analysed according to the desired objective, emphasizing that values higher than 5% can greatly compromise the final nutritive value of elephant grass silage