Effective Rumen Degradability Research Articles

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.

Effect of extrusion with molasses on the rumen undegradable protein fraction of canola oilcake meal and sweet lupins

The effect of the extrusion of canola oilcake meal (COM) and crushed sweet lupins (CSL) with molasses on the dry matter (DM) and crude protein (CP) degradability was determined in situ. Locally sourced (SOILL Moorreesburg, South Africa) COM and CSL, with the addition of 6% molasses, were extruded at a maximum temperature of 116 °C. A total of six Dohne Merino wethers (± 80 kg), fitted with rumen cannula, were used in this trial. Samples in polyester bags (5 g) were incubated in the rumen of the sheep at intervals of 0, 2, 4, 8, 16, 24, and 48 h. The DM and CP disappearances from the rumen were determined and degradability parameters were estimated. Extrusion increased the potentially degradable CP fraction by 43.5%. At each outflow rate, the average CP effective degradability of COM (68.2%) was lower than that of CSL (78.0%). Extrusion substantially lowered the CP effective degradability for both protein sources at every outflow rate tested. The biggest effect was seen at 0.08/h, where effective degradation was lowered by 25.6%. Extrusion with molasses was found to modify ruminal degradation parameters of both canola oilcake meal and crushed sweet lupins, while also decreasing the effective rumen degradation, especially at faster outflow rates. Thereby, the rumen undegradable protein fraction was increased by 85.4%. This study shows that COM and CSL extruded with 6% molasses can substantially increase RUP.

Comparing the effects of gamma ray and alkaline treatments of sodium hydroxide and calcium oxide on chemical composition, ruminal degradation kinetics and crystallinity degree of soybean straw

This research was conducted to compare the effects of gamma ray (GR) at doses of 100 and 150 kGy, alkaline treatments of sodium hydroxide (NaOH) and calcium oxide (CaO) at concentrations of 50 and 160 g/kg of dry matter (DM) respectively, and their combined use on chemical composition, ruminal degradation kinetics and crystallinity degree of soybean straw (SBS). After processing, the chemical composition of the samples was determined using the AOAC standard methods. Ruminal degradability trial was carried out by the nylon bag technique. Crystallinity degree of the samples was investigated through X-ray diffraction (XRD) technique. Using alkaline compounds in processing of SBS significantly increased the Ash amount (P < 0.0001). The greatest value was observed in CaO and CaO + GR treatments (100 and 150 kGy). The crude fiber (CF) of samples was reduced due to the effect of gamma irradiation, alkaline compounds, and their combination (P < 0.0001). Samples irradiated with 150 kGy dose of GR had the least amount of CF. The processing increased the effective rumen degradability (ERD) of DM for SBS at rumen outflow rates of 0.02, 0.05, and 0.08/h (P < 0.0001). The greatest amounts at the mentioned outflow rates were observed in GR (100, and 150 kGy), and NaOH + GR (100 and 150 kGy) treatments. Different treatments reduced the crystallinity degree of SBS compared to the control group. The least crystallinity percentage was observed in GR (150 kGy) treated samples. Totally, gamma irradiation, alkaline treatments and their combined use improved the nutritional value of SBS. In this respect, gamma irradiation was more effective than alkaline compounds.

Effects of corn straw treated with CaO on rumen degradation characteristics and fermentation parameters and their correlation with microbial diversity in rumen

The objectives of this study were to investigate the degradation characteristics and fermentation parameters of corn straw treated with different concentrations of calcium oxide (CaO) and degradation characteristics and fermentation parameters of samples in relation to microorganisms diversity in the rumen. Corn straw with 60 % moisture were treated with four concentrations of CaO (0 %, 3 %, 5 %, and 7 % of dry straw weight) respectively: i) The nylon bag technology method was used in estimating the rumen effective degradability, and each treatment was performed eight times. Then, the degradability of dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined by taking nylon bags from rumen at 0 h, 4 h, 8 h, 12 h, 24 h, 48 h and 72 h, respectively. ii) The fermentation parameters of corn straw were measured by rumen simulation technology in vitro. The mixture was measured at different times (6 h, 12 h, 24 h and 72 h) for the determination of ammonia nitrogen (NH3–N), volatile fatty acids (VFAs) indexes and rumen microbes. iii) The free online platform of Majorbio Cloud Platform was used in evaluating microbe diversity, abundance, and taxonomic composition in the rumen. Species difference analysis was designed, each treatment had three replicates, and 48 samples in total were used. iv) The correlations among effective degradability, fermentation indexes, and rumen microorganisms of corn straw treated by CaO were analyzed by means of an online platform. The results showed that i) the effective rumen degradability of corn straw treated with CaO significant differed among treatments (P < 0.01). The degradability of DM, NDF, and ADF in 7 % and 5 % treatments were higher than that in other treatments (P < 0.01). Soluble and rapidly degraded components in corn straw had significant higher in 5 % and 7 % treatments than in the 0 % and 3 % treatments. ii）The concentrations of acetate, propionate, butyrate, and total VFA at 6 h in vitro had significant differences (P < 0.01) or obvious upward tendency with increasing concentration of CaO. iii) Alpha index analysis revealed that rumen microorganisms diversity and abundance obviously decreased from 0 % to 7 % treatment in 6 h fermentation. Rikenellaceae_RC9_gut_group at the genus level decreased in the top 15 species in terms of average abundance (P < 0.01), but the most abundant genus Prevotella_1 had an upward tendency in 6 h incubation (P = 0.066). iv) Correlation analysis demonstrated that Prevotella_1 and Prevotellaceae_UCG-003 had positive correlations with acetate, propionate, total VFA, and DM, NDF, and ADF degradability (P < 0.01). Overall, corn straw treated with CaO at 5 % and 7 % can improve rumen effective degradability and promote the fermentation of corn straw, especially promoting Prevotella_1 enrichment in the straw in a short time. In terms of cost saving, 5 % CaO treatment is the best choice.

Effect of amylases and storage length on losses, nutritional value, fermentation, and microbiology of silages of corn and sorghum kernels

This study evaluated the effect of two commercial amylases with known activity at low pH and storage length on fermentation profile, microbial diversity, and effective rumen degradation (ERD) of silages of rehydrated kernels of sorghum (RES) or flint corn (REC). Mature kernels were ground through a 1 mm diameter mesh screen with a stationary hammer mill and manually rehydrated to achieve a similar dry matter (DM) concentration (650 g/kg of fresh) for ensiling (4.74 ± 0.30 kg/silo). Treatments were formed using a 2 × 3 × 2 factorial combination of grain type (RES and REC), enzyme [control and amylases AMG (300 AGU/mL) and GAM (138 AGU/mL), both at 0.35 mL/kg of fresh kernels], and storage length (30 and 180 d), with six replicates. The ERD of DM was evaluated in situ with a 2-pool model (A and B fractions) and incubations for 0, 3, 6, 12, 18, and 48 h. The proportional change in ERD mass during silage storage (% of ensiled) was calculated. Lactic acid bacteria (LAB) and spore-forming aerobic bacteria (SAB) were quantified and identified. The loss of DM (6.8 vs. 5.3% of ensiled) and starch (23.9 vs. 13.6% of ensiled) were higher (P < 0.01) for REC than RES. The RES had higher (P < 0.01) DM fraction A (398 vs. 325 g/kg of DM) and ERD (593 vs. 554 g/kg of DM) and lower (P < 0.01) kd of DM fraction B (3.14 vs. 3.33%/h) than REC. Ensiling increased ERD mass of both kernels (+6.8% of ensiled). The RES showed a faster increase (P = 0.04) in ERD mass in response to ensiling than REC. Both amylases and a longer duration of storage reduced (P < 0.01) the starch content and increased (P < 0.01) DM loss. Enzymes induced a faster increase (P < 0.01) in ERD mass relative to control but reduced the gain in ERD mass in extended storage. Longer storage increased (P < 0.01) the ERD content and the pool size of fraction A of both RES and REC. Lactic acid was the primary organic acid in silage, followed by propionic acid. Long storage of sorghum increased (P < 0.01) butyrate and there was no effect of grain type and enzyme on butyrate at 30 days of storage. The RES ensiled for 180 days without enzyme had the highest (P < 0.01) butyrate. The species Levilactobacillus brevis, Lentilactobacillus buchneri, Lactiplantibacillus plantarum, and Pediococcus acidilactici were the most frequent, but in general, amylases reduced numerically their population. The SAB had a greater diversity and lower population than LAB. We concluded that RES was more degradable in the rumen and had a lower loss during storage than REC. The highest ERD mass recovery was observed for long storage without amylase. The amylases seem to be an option only when storage length is short. The LAB population dominated sorghum and corn kernels silage fermentation. Most microorganisms identified were involved in organic acids and alcohol metabolism.

Effect of flaking on the digestibility of corn in ruminants.

In this study, we aimed to assess the effect of flaking on the nutrient digestibility of corn grain in ruminants. In this regard, in vitro rumen fermentation, in situ rumen degradability, and in vivo metabolic experiments were performed. The automated gas production technique was used for the in vitro fermentation experiments. Six types of corn flakes with various degrees of gelatinization (32%, 41%, 48%, 66%, 86%, and 89%) were ground and incubated in rumen fluid to measure rumen fermentation characteristics and digestion rate. The in situ degradability of ground corn, whole corn, and corn flakes with 62% and 66% gelatinization was measured by incubation in the rumen of two cannulated Holstein cows. In vivo metabolic experiments were performed using 12 crossbred goats (29.8 ± 4.37 kg) using a 3 × 3 Latin square design. The dietary treatments consisted of ground corn and flaked corn with 48% or 62% gelatinization. In vitro experiments showed that as the degree of gelatinization increased, the digestion rate increased linearly, while the discrete lag time decreased linearly (p < 0.05). The effective rumen dry matter degradability, determined by in situ fermentation, was 37%p lower in corn flakes than ground corn, assuming a passage rate of 6%/h (p < 0.01), and there was no difference between the two flakes. In the in vivo experiment, there was no difference in dry matter intake, average daily gain, feed efficiency, and nitrogen utilization among the treatment groups (p > 0.05); however, the crude fat digestibility was lower for corn flakes than for ground corn (p < 0.05). To summarize, the rate of fermentation of corn flakes increased as the degree of gelatinization increased. However, non-ground corn flakes had lower rumen digestibility and did not improve in vivo apparent nutrient digestibility, compared with ground corn. In contrast to the assumption that flaked corn provides more energy to ruminant animals than ground corn, we conclude that the digestibility and energy value of corn flakes are lower than those of ground corn if mastication does not sufficiently reduce the particle size of corn flakes.

Analysis of Nutrient Composition, Rumen Degradation Characteristics, and Feeding Value of Chinese Rye Grass, Barley Grass, and Naked Oat Straw.

Simple SummaryLimited studies have been reported so far on the rumen degradability characteristic of low-quality forage. In the current study, three low-quality forages (Chinese rye grass, barley grass, and naked oat straw) were selected. Various nutritional parameters such as rumen degradation characteristics, chemical composition and feeding value of three roughages were studied in detail. Among the three roughages, the Chinese rye grass (Leymus chinensis) was superior in terms of rumen degradability characteristics, chemical composition and feeding value.The current study was designed to investigate the chemical composition, rumen degradation characteristics, and feeding value of three roughages commonly used in Asia as ruminant feed, including Chinese rye grass (CRG), barley grass (BG), and naked oat straw (NO). Four Holstein Friesian cows equipped with permanent rumen fistulas were chosen for experimental trials in the current study. The nylon bag method was carried out to measure the crude protein (CP), acid detergent fiber (ADF), ruminal degradability of dry matter (DM), and neutral detergent fiber (NDF). Our analysis revealed that the contents of CP in the CRG (9.0%) and BG (8.9%) were higher than in the NO (5.94%). The contents of NDF in the CRG (64.97%) and NO (63.83%) were lower than in the BG (67.33%), and the content of ADF in the CRG (37.03%) was lower than in the BG (37.93%) and NO (38.28%). The ED values of DM in the NO and CRG were significantly higher (p < 0.001) than in the BG. The effective degradability (ED) values of NDF were the highest in the CRG and lowest in the NO (p < 0.001). In addition, the ED values of ADF were the highest in the CRG and lowest in the BG (p < 0.001). The ED value of CP in the CRG was significantly higher than that in the BG and NO (p < 0.001). The estimated total digestible nutrients (TDN) (54.56%) and DM degradation rate (DDM) (60.06%) of the CRG were higher than those of BG and NO. In addition, the expected DM intake (DMI), estimated relative feed value (RFV), and estimated relative feed quality (RFQ) of the BG were lower than those of the CRG and NO. Altogether, based on our findings, we concluded that the nutritional quality, feeding value and effective rumen degradation rate of CRG were better than of BG and NO.

Effect of extrusion on the rumen undegradable protein fraction of lupins

Lupins are highly degradable in the rumen, and do not provide enough bypass protein for high-producing ruminant animals. The effects of extrusion on dry matter (DM) and crude protein (CP) rumen degradability of Lupinus albus and Lupinus angustifolius were determined in situ. Samples of both types of lupin were extruded at maximum temperature, which reached 116 °C. Six Dohne Merino wethers fitted with rumen cannulas were used in this trial. Samples were incubated in the rumen at intervals of 0, 2, 4, 12, 36, and 48 hours. This procedure was repeated in two sheep per treatment and in three periods, giving a total of six observations for each variable. Extrusion lowered the soluble fraction of CP and increased the potential degradable fraction without affecting its rate of degradation. It also lowered the effective degradability of CP of both types of lupin by 28% at an outflow rate of 0.08% per hour. No differences were observed between types. Extrusion modified the ruminal degradation parameters and decreased effective rumen degradation, especially at faster outflow rates. Thus, the rumen undegradable protein (RUP) fraction of lupins was increased by extrusion and lupins could be used more efficiently in ruminant diets. This study showed that the benefits of extrusion could be reached at a relatively low temperature of 116 °C to reduce the possibility of heat damage.

Comparative chemical composition and rumen degradation of common reed and elephant grass in urban/peri-urban dairying systems in Uganda

ABSTRACT Urban/peri-urban dairying in East Africa used to be typified by elephant grass (Pennisetum purpureum, Schumach) as the primary forage. However, the ever-declining space for farming has made forage cultivation increasingly difficult. As a coping strategy, farmers are harvesting vegetation biomass from natural environment, particularly common reed (Phragmites australis, Cav.) from wetlands. This study aimed to compare elephant grass and common reed in terms of chemical composition and in situ rumen degradation. Samples were collected (in dry and wet seasons) and analyzed for chemical composition, and in situ rumen degradation of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) determined. Rumen degradation was determined by incubating triplicate nylon-bagged samples in rumens of three cannulated Ankole–Friesian crossbred steers. The CP content ranged from 10.8% to 16.2% DM (common reed), and 9.9–12.5% DM (elephant grass). Common reed showed lower DM, and ADF compositions, and higher effective rumen degradability of DM, CP, and NDF in both seasons. For both forages, CP content was higher during the dry season, while effective rumen degradability of DM, CP, and NDF were higher in the wet season. In summary, the chemical and rumen degradation results suggest that common reed may be nutritionally superior to elephant grass.

Slow-Release Urea as a Sustainable Alternative to Soybean Meal in Ruminant Nutrition

Three experiments were conducted to evaluate the feasibility of using a commercial slow-release urea product (SRU; Optigen®, Alltech Inc., Nicholasville, KY, USA) as a partial replacement for vegetable protein sources in cattle diets. The first experiment was an in vitro rumen fermentation that evaluated the effect of replacing soybean meal (SBM) nitrogen with nitrogen from either SRU or free urea in diets varying in forage:concentrate ratios. The second experiment examined the effect of replacing SBM with SRU on in situ dry matter and nitrogen degradability in the rumen. In the third experiment, a feeding trial was conducted to evaluate the effect of replacing SBM (0% as-fed SRU) with 1% or 3% as-fed SRU on feed carbon footprint (CFP; total greenhouse gas emissions associated with the life cycle of feed raw materials) and the toxicity potential of SRU in growing beef cattle. Results showed that replacing SBM with SRU up to 1.3% did not negatively affect in vitro rumen fermentation parameters. Supplementing SRU favourably decreased ruminal accumulation of ammonia and lactic acid when compared to free urea. There was no significant effect on effective rumen degradability of dry matter and nitrogen when one-third of SBM was replaced by SRU in the in situ study. Compared with the 0% SRU diet, feed CFP decreased by 18% and 54% in 1% SRU and 3% SRU diets, respectively. Additionally, feeding up to 3% SRU diet to beef cattle did not affect health and intake, and blood hematological and biochemical indices were within the physiological range for healthy bulls, suggesting no indication of ammonia toxicity. Overall, these results indicate that SRU can be used as a sustainable alternative to partially replace vegetable protein sources in ruminant diets without compromising rumen function and health of ruminants.

PSVII-35 Late-Breaking Abstract: Microwave heat treatment feed effect on ruminal degradability and intestinal protein digestibility - a brief review

Abstract Rumen degradability of crude protein (CP) of feed is a major factor that determines the utilization of CP in ruminant production. This study briefly reviewed the findings from six international studies of microwave (MW) heat treatment effect on feed CP rumen degradability and intestinal CP digestibility. Six in vitro studies of concentrate feed (canola seed, canola meal, soya bean meal, cottonseed meal, corn, and barley) showed a decrease in effective rumen degradability of dry matter and protein by 4–40% and 17–40%, respectively compared to control group (untreated concentrate feed). Among the six studies, four studies identified the MW heat treatment effect on intestinal protein digestibility. Due to MW heat treatment, canola seed, canola meal, soya bean meal, and cottonseed meal showed an increase in intestinal CP digestibility by 17%, 20%, 21%, and 19%, respectively. Overall the briefly reviewed studies showed that, MW heat treatment substantially reduced feed CP ruminal degradability and increased in vitro CP digestibility of ruminally undegraded CP.

PSIX-17 Investigation of rumen starch and protein degradation kinetics in relation to corn processed by super-conditioned pelleting, extruding and puffing

Abstract The objective of this study was to investigate the rumen dry matter (DM), starch and protein degradation kinetics of an Iranian corn grain (single crass 702) processed using different thermal processing methods including 1) grinding (G, 2mm), 2) super-conditioned pelleting (SCP; moisture 20%, retention time 6 min and conditioning temperature 95°C), 3) puffing (PUF; puffing temperature 200°C, hot air velocity 25 m/s, feed rate 100 g/m) and 4) extruding (EX; moisture 20%, temperature of melting zone 75°C and die zone 125°C and time 150s). Three lactating Holstein cows fitted with a ruminal cannula were used. Samples were incubated into the rumen for 2, 4, 8, 12, 24, and 48 h. Rumen degradation kinetics were fitted based on equations. Data were analyzed by GLM procedure of SAS (P &amp;lt; 0.05) using a completely randomized design with 6 replications for every treatment. Rapidly soluble fraction (a) and fractional rate constant (c) of DM were higher (P &amp;lt; 0.01) in PUF and EX corns than SCP. The lowest (P &amp;lt; 0.05) slowly degradable fraction (b) of DM was found in SCP. The highest (P &amp;lt; 0.01) effective rumen degradability of DM (ERDM), starch (ERDS) and protein (ERDP) were observed in the EX, followed by PUF, SCP and G corns. Fraction a of starch and protein was significantly greater (P &amp;lt; 0.01) in EX, PUF and SCP than G. The rate of degradability (c) of starch, DM and protein in EX and PUF were similar and higher (P &amp;lt; 0.01) than SCP and G, but c for starch in EX was greater (P &amp;lt; 0.01) than PUF and fallowed by SCP and G corns. In conclusion, the super-conditioning of corn as a new method of corn processing increased rapidly soluble fraction starch similar to PUF and EX corns and effective rumen degradability of starch was significantly increased in SCP corn.

Effect of Hybrid Rye and Maize Grain Processing on Ruminal and Postruminal Digestibility Parameters

Abstract The aim of the study was to determine the effect of the method of fragmentation of hybrid rye and maize grain on digestibility parameters for ruminants. Varying degrees of fragmentation – none (whole grains; WG), crushed (CG) or ground to pass through a 4.0 (GG4.0) or 1.5 mm (GG1.5) screen – were estimated by the in sacco nylon bag technique, in vitro true digestibility (IVTD), and the in vitro gas production (GP) technique. WG, CG, GG4.0 and GG1.5 were categorized as none, slight, moderate and extensive fragmentation of the grain kernel, respectively. Three non-lactating cows fitted with ruminal and duodenal cannulas were used to determine the effective rumen degradability (ERD) and intestinal and total tract digestibility (ID and TTD, respectively) of dry matter (DM), crude protein (CP) and starch. IVTD was determined with an ANKOM DaisyII Incubator, and GP and in vitro organic matter digestibility were determined with an ANKOMRF Gas Production System. Dry matter, CP and starch of hybrid rye grain were rapidly degraded in the rumen, and this degradability as well as ID and TTD was only marginally affected by the method of kernel fragmentation; however, among the methods used, the ERD of GG4.0 rye was the lowest. On the other hand, the greater the degree of kernel fragmentation, the higher ERD, ID and TTD were obtained for the DM, CP and starch of maize grain. In summary, rye grain is more susceptible to fermentation in the rumen than maize grain, but the means of grain processing may alter the rate, extent and site of their digestion, particularly for maize grain.

Effect of different corn processing methods on starch gelatinization, granule structure alternation, rumen kinetic dynamics and starch digestion

In this study, the effect of four corn processing methods including grinding (G), dry-rolling (DR), steam-flaking (SF) and super-conditioning (SC), on corn starch parameters viz. gelatinization, granule structure alternation, rumen kinetic dynamics and the extent and site of starch digestion were compared. In addition, physical properties, chemical composition, gas production (GP), pH, ammonia nitrogen (NH3-N) and volatile fatty acids (VFAs) of batch culture after 24 h were determined. The apparent density of the SC corn resembled that of the G corn (0.758 vs 0.837 kg/L); however, its geometric mean of particle size (3.39 mm) was greater than that of the G corn (1.56 mm) and smaller than that of the SF corn (5.43 mm). In addition, dry matter (DM), ether extract (EE) and neutral detergent fiber (aNDF) were not significantly affected (P > 0.01) by the processing method. The starch content of the SC and SF corns were greater (P < 0.01) than that of the DR and G corns. GP after 6, 12 and 24-h incubation and GP rate were greater (P < 0.01) in the SC corn; nevertheless, GP at 48-h incubation was the same in SC and SF corns (P> 0.01). The pH and NH3-N of batch culture after 24-h were significantly lower (P < 0.01) in the SC corn than in the other processing methods. The SF corn increased (P < 0.01) acetate and acetate to propionate ratio, but decreased (P < 0.01) propionate while the SC corn reduced (P < 0.01) acetate and acetate to propionate ratio, but raised propionate (P < 0.01). The time required for 25 % and 75 % fermentation of substrate was significantly reduced by the SC corn (P < 0.01). The highest starch gelatinization (P < 0.01) was obtained from SC, followed by SF corn. The rapidly soluble fraction (a) for DM, starch and CP was greater (P < 0.01) in the SC corn than in other processing methods; however, the slowly degradable fraction (b) for DM and starch was lower (P < 0.001) in the SC corn than in other methods. Although the effective rumen degradability of DM (ERDDM) remained unchanged (P> 0.01), the effective rumen degradability of starch (ERDS) and the effective rumen degradability of protein (ERDCP) were found to be greater in the SC corn than in other processing methods (P < 0.01). Ruminal and total tract digestibility of starch increased (P < 0.01) in the SC corn, but intestinal DM (P = 0.002) and starch (P < 0.01) digestibility of the SC corn diminished. The ruminal CP digestibility was lower (P = 0.06) in the SF corn than in the SC corn; however, SC and SF corns showed greater intestinal (P = 0.005) and total tract (P = 0.021) CP digestibility. The results indicated more starch gelatinization in the SC process in terms of higher exposure of particles to conditioning and homogenization, which enabled the alteration of starch granules and the protein matrix in the endosperm of corn. Furthermore, the SC process could influence the rumen kinetic dynamics, the extent and site of starch digestion as well as the efficiency of using starch under in vitro and in situ conditions.

Effect of heat treatment and heat treatment in combination with lignosulfonate on in situ rumen degradability of canola cake crude protein, lysine, and methionine

The aim of this study was to determine the effect of heat treatment alone or in combination with the addition of lignosulfonate (LSO3) on canola cake protein, lysine, and methionine degradation in the rumen. Cold-pressed canola cake was left untreated, heated at 90, 110, 130, or 150 °C, or processed with 5% of LSO3 (in dry matter) and then heated. Effective rumen degradability of crude protein (CP), lysine, and methionine was less for treated than untreated canola cake (P &lt; 0.05) and decreased with increased temperature of heating, but particularly when canola cake was heated at 150 °C (quadratic, P &lt; 0.01). In general, effective rumen degradability of CP, lysine, and methionine was less for canola cake heated at 130 °C in combination with LSO3 compared with canola cake heat treated only (quadratic × LSO3 interaction, P ≤ 0.07). Results of this study indicate that high temperature heating (130 °C or greater for 60 min) may be necessary to protect canola cake protein from degradation in the rumen, and the combination of heat treatment and LSO3 may be more effective in protecting canola cake protein, lysine, and methionine from degradation in the rumen than the use of heat treatment only.

Recombinant fibrolytic feed enzymes and ammonia fibre expansion (AFEX) pretreatment of crop residues to improve fibre degradability in cattle

Low digestibility of crop residues limits their use as animal feeds. The study examined the potential of Ammonia Fibre Expansion (AFEX) technology and dietary supplementation of a preselected recombinant xylanase to improve the in situ degradability of four crop residues for ruminants. AFEX pretreatment uses anhydrous ammonia, moisture, moderate temperature, and a short period of high pressure and results in partial lignin solubilization and hemicellulose hydrolysis, and increased surface area of substrate for microbial attachment. In situ neutral detergent fibre degradabilities of untreated (control) and AFEX pretreated crop residues (barley straw, corn stover, rice straw, and wheat straw) were determined in 8 heifers using a 2-period cross-over design with two dietary treatments (without and with XYL10C; 1,4-β-xylanase; recombinant enzyme from glycoside hydrolase family 10 produced by Aspergillus niger). The enzyme was diluted in water and applied to the barley straw (6.6 × 104 IU enzyme/kg straw dry matter) component of the basal diet (30 g/100 g diet dry matter) and to the control and AFEX crop residues incubated in situ. There were no interactions between enzyme and crop residues for A, B, or A + B fractions, indicating no enzyme × substrate specificity. Averaged across crop residues, enzyme slightly decreased the A fraction (P < 0.001) and slightly increased the B fraction (P = 0.02), such that there was no overall effect on A + B (P = 0.21). However, there were significant interactions between enzyme and AFEX for kd (P = 0.026); enzyme had no effect on control crop residues but it increased kd of AFEX residues by 12% (0.0323 vs. 0.0361 /h). As a result, xylanase supplementation increased the effective rumen degradability of crop residues by about 3%, but only when they were pretreated with AFEX (interaction, P ≤ 0.098). AFEX greatly increased effective ruminal degradability (+ 28 to + 126% depending upon the crop residue; P < 0.001), mainly by increasing the B fraction and decreasing the undigested fibre fraction, indicating increased accessibility of substrate to rumen microbial enzymes. The study demonstrates the tremendous potential of AFEX treatment to improve the feeding value of crop residues. Enzyme XYL10C was more effective for AFEX crop residues, possibly due to increased accessibility to substrate, suggesting that this enzyme may be more effective for less lignified and pretreated feeds.

Microwave irradiation of whole soybeans in ruminant nutrition: Protein and carbohydrate metabolism in vitro and in situ.

Whole soybeans serve as one of the main sources of protein in ruminant nutrition. Different processing methods have been employed for ruminal protein protection. The present study was conducted to determine the effects of microwave irradiation [900 W; 2, 4 and 6 min] on quality, ruminal degradability and estimated in vitro intestinal digestibility of availability soybean crude protein. This experiment was performed in a completely randomized design with seven treatments including control (no processing), along with 2, 4 and 6 min of microwave irradiation on whole and ground soybeans. Protein and carbohydrate fractions were determined according to Cornell Net Carbohydrate and Protein System (CNCPS). Triplicates of the samples were incubated in the rumen of three cannulated Holstein steers for up to 48 hr. Microwave irradiation increased neutral detergent insoluble nitrogen, metabolizable protein content and resulted in a lower effective rumen degradability and in vitro gas production. Nevertheless, longer processing time led to higher unavailable protein and carbohydrate fractions. In the main, microwave irradiation of ground samples for 4 min increased metabolizable protein content, without negative effects on protein and carbohydrate availability.

In situ rumen degradation of kernels from short-season corn silage hybrids as affected by processing.

The objective of this in situ study was to evaluate the rumen degradability of kernels from short-season corn hybrids grown for silage in Western Canada (Lacombe, AB) and determine whether decreasing kernel particle size would enhance ruminal degradability in a similar manner for all hybrids. The study was a completely randomized design with 3 beef cows (replicates) and a 6 (hybrid) × 3 (particle size) factorial arrangement of treatments. Kernels were processed to generate three different particle sizes: large (2.3 mm), medium (1.4 mm), and small (0.7 mm). Processed samples were incubated in the rumen for 0, 3, 6, 12, 24, and 48 h using the in situ method and degradation kinetics of DM and starch were determined. Effective rumen degradability (ED) was estimated using a passage rate of 0.04 (ED4), 0.06 (ED6), and 0.08/h (ED8). Hybrids exhibited a range in whole plant DM content (23.7 to 25.0%), starch content (15.9 to 28.1% DM), kernel hardness (21.9 to 34.4 s/20 g) and density (3.57 to 4.18 g/mL), and prolamin content (8.24 to 11.34 g/100 g starch). Differences in digestion kinetics among hybrids were generally more pronounced for starch than DM. The hybrids differed in starch degradability (P < 0.05), with earlier maturing hybrids having lower A fraction, lower k d, and lower ED, with hybrid effects on ED being accentuated with faster passage rate. Kernel DM content (r = -0.85, -0.87), hardness (r = -0.89, -0.86), and density (r = -0.84, -0.85) were negatively correlated with ED4 and ED8 of starch, respectively, due mainly to decreased k d of fraction B. Reducing the particle size of kernels increased ED of starch due to increased A fraction and k d of the B fraction. A tendency (P = 0.09) for hybrid × processing effects for ED6 and ED8 indicated that processing had greater effects on increasing ED of starch for earlier maturing hybrids. We conclude that short-season hybrids that mature early may have lower ED of DM and starch and would benefit from prolonged ensilage time. Kernel processing during silage making is recommended for short-season corn hybrids as a means of enhancing rumen availability of starch.

Botanical Composition and In Situ Dry Matter Degradability of Legume- Grass Mixture Pasture Fertilized with Different Amounts of Nitrogen

This study was conducted to determine the effects of different nitrogen (N) fertilizer levels on botanical composition, dry matter (DM) yield, chemical composition, in situ ruminal DM and NDF degradability and net energy lactation (NEL) of a native legume-grass mixture pasture. Field and degradability trials were arranged in a Complete Randomized Block Design with three replicates. Pasture was fertilized at six levels of N fertilizer (ammonium nitrate, N0, N50, N100, N150, N200 and N250 kg/ha). Three rumen cannulated Holstein Friesian heifers (3-4 year old) were used. Feed samples were incubated for 0, 8, 12, 24, 36, 48, 72 and 96 h. Application of nitrogen fertilizer results indicated that nitrogen fertilizer decreased the legumes ratio (LR) of pasture, approximately 22.4%, Although N fertilizer increased the grass ratio (GR) of pasture approximately 55.8%. Dry matter (DM), Net energy lactation (NEL, Mcal/kg) and ash contents of pasture were increased by increasing N fertilizer level. However, when N fertilizer level increased acid detergent fiber (ADF) concentration of pasture decreased. Application of the different rate of nitrogen fertilizer had no effect on in situ rumen degradability of DM and NDF of pasture. It was also found that there was the significant positive relationship between effective NDF degradability at 48 h. rumen incubation period and different level of N fertilizer. In addition, it was determined that there was a linear and quadratic positive relationship between DM yield and different nitrogen doses. In conclusion, different rates of nitrogen application changed botanical composition, decreased ADF content and increased NEL and effective rumen degradability of neutral detergent fiber (EDNDF 48 h.) of pasture.

Potential nitrogen to energy synchronization, rumen degradation kinetics, and intestinal digestibility of blend pelleted products of new co-products from bio-fuel processing, pulse screenings and lignosulfonate compound in dairy cows

Recently, a new co-product (carinata meal) has been emerged from the bio-fuel processing industry, which nutritional value has not been yet fully understood and evaluated nor even registered as a feed for ruminants. So, it becomes an urgent need to explore the potential of this new coproduct in livestock feeds when blend with other feedstuffs. The aim of this project was to develop and test blend pelleted products based on combination of new and conventional co-products from bio-fuel (carinata meal) and bio-oil (canola meal) processing, pea screenings and lignosulfonate compound (feed additive) at different levels in order to efficiently utilize the new co-product and optimize various nutrient supply in dairy cows. The eight blend pelleted products were: BPP1: lignosulfonate 0.0% + carinata meal 50.0% + pea screenings 50.0%; BPP2: lignosulfonate 4.8% + carinata meal 47.6% + pea screenings 47.6%; BPP3: lignosulfonate 0.0% + carinata meal 75.0% + pea screenings 25.0%; BPP4: lignosulfonate 4.8% + carinata meal 71.4% + pea screenings 23.8%; BPP5: lignosulfonate 0.0% + canola meal 50.0% + pea screenings 50.0%; BPP6: lignosulfonate 4.8% + canola meal 47.6% + pea screenings 47.6%; BPP7: lignosulfonate 0.0% + canola meal 75.0% + pea screenings 25.0%; BPP8: lignosulfonate 4.8% + canola meal 71.4% + pea screenings 23.8%. All blended proportions were on dry matter (DM) basis. The results were compared between blend pelleted products based on new co-product carinata meal and conventional co-product canola meal; high and low level of inclusion of co-products (contrarily, low and high level of inclusion of pea screenings); and inclusion and no inclusion of lignosulfonate compound in terms of rumen degradation kinetics, indigestible neutral detergent fiber(NDF) at 288 h (iNDF), hourly effective rumen degradation ratios/potential nitrogen-to energy synchronization and intestinal digestion of rumen undegraded nutrients. The results showed that carinata based pelleted product BPP3 and BPP4 had higher (P < 0.05) level of rumen undegraded protein (BCPDVE: 233 and 239 g/kg DM; RUPNRC: 210 and 216 g/kg DM; respectively) than the other blend pelleted products. The BPP3 also showed higher (P < 0.05) effective degradation of NDF (EDNDF: 64 g/kg DM) than the other blend pelleted products except BPP4 and BPP7 (56 and 61 g/kg DM; respectively). The iNDF was higher in canola based pelleted product BPP7, while the values were ranged from 5.3 to 12.5% DM. Intestinal absorbable feed protein (IADP) was higher in BPP4 (168 g/kg DM) than the other pelleted products except BPP3; however, BPP3 showed higher (P < 0.05) total digestible protein (TDP: 405 g/kg DM) than the other blend pelleted products followed by BPP4 (383 g/kg DM) and BPP7 (370 g/kg DM). In addition, BPP3 showed higher (P < 0.05) total digestible NDF (TDNDF: 139 g/kg DM) than the other blend pelleted products. In summary, the new co-product (carinata meal) based pelleted products (BPP1 to BPP4) contained higher RUP (+56 g/kg DM), lower EDCP (–24 g/kg DM), higher EDNDF (+2.9%), lower iNDF (−4.2% DM), higher IADP (+55.7 g/kg DM) and higher TDP (+32 g/kg DM) than canola based pelleted products (BPP6 to BPP8). Therefore, the result of this study suggest that the Carinata meal based pelleted products BPP3 and BPP4 can be used as high quality protein supplements for dairy cows.