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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 (Forage) for 1 week, followed by stepwise adaptation during one week to a high-concentrate diet (HC; 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 HC. 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 of the grain 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 crude protein, fat, starch, NDF, ADF and NFC increased with HC 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 HC; however, α diversity (number of ASVs) showed recovery in wk 3 and 4 on HC; in addition, microbial ß diversity did not change from wk 2 on HC onwards. 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 HC. However, the hindgut microbial diversity of cows adapted after 3 weeks of consuming the starch-rich ration. Thus, feeding 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 non-forage 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.

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In current dairy production, dietary energy is always excessively provided with a high-concentrate diet feeding to improve milk production. However, this feeding practice disturbed the rumen microbial ecosystem and the balance between ruminal energy and nitrogen, resulting in decreased nutrient fermentability, which in turn declined the milk yield of dairy cows. Therefore, supplementation of dietary degradable nitrogen may be helpful for high dairy production. In this study, we evaluated the regulatory effects of easily utilized enzymatic hydrolyzed cottonseed peptide (EHP) supplements on rumen microbiota communities and rumen nutrient fermentability under high-concentrate feeding. For this purpose, a gradient concentrate of EHP (from 0.2 to 1.0%) was added to the high-concentrate basal substrates for an in vitro experiment. Each treatment contained three replicates, with three bottles in each replicate. Rumen fermentable parameters included microbial protein content, volatile fatty acids, and ammonia-N; the rumen nutrient degradability of dry matter, crude protein, neutral detergent fiber, acid detergent fiber, ether extracts, calcium, and phosphorus were further investigated after in vitro fermentation for 72 h. Then, rumen microbiota communities and their correlation with ruminal fermentation parameters and rumen nutritional degradability were analyzed to understand the regulatory mechanism of the EHP supplements on rumen fermentability. Results indicate that treatment with 0.6% of EHP supplements had the highest content of acetate, butyrate, and neutral detergent fiber degradability among all treatments. Furthermore, EHP supplements significantly increased the relative abundance of rumen cellulose and starch-degrading bacteria such as Ruminococcus, Bifidobacterium, and Acetitomaculum, and the high nitrogen utilizing bacteria Butyrivibrio and Pseudobutyrivibrio, which may further promote the rumen carbohydrate and nitrogen metabolism. In summary, supplementation of easily degraded small peptides helps reestablish rumen energy and nitrogen balance to promote the rumen fermentable functions and nutritional degradability under high-concentrate diet feeding circumstances. These findings may further promote dairy production.

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BACKGROUND: The aim of this research was to investigate the influence of bamboo grass (Tiliacora triandra, Diels) pellet (BP) containing phytonutrients on rumen fermentation under various level of roughage (R) to concentrate (C) ratios. The experimental treatments were randomly assigned following a completely randomized design using a 3 × 5 factorial arrangement. The first factor was ratios of R:C at 100:0, 70:30, and 30:70 and the second factor was BP supplementation levels at 0, 1, 2, 3, and 4% of dry matter substrate, respectively. RESULTS: The ratio of R:C significantly enhanced rumen gas production especially when increased level of concentrate. Moreover, dry matter degradability of fermentation were improved (P < 0.01) by R:C and level of BP supplementation, and there was an interactive effect. The ammonia nitrogen (NH3 -N) concentration, protozoal population and methane (CH4 ) production were remarkably influenced (P < 0.01). There were highly significant interactive effects between ratio of R:C and level of BP supplementation. Furthermore, fermentation parameters especially those of propionate (C3 ) concentration was profoundly increased by higher ratio of R:C and by the BP supplementation, interactive effect (P < 0.01). Notably, both level of R:C and BP supplementation significantly reduced NH3 -N concentration and CH4 production. Interactive effects of both factors were obtained (P < 0.01). CONCLUSION: The ratio of R:C at 30:70 with BP supplementation at 4% could enhance fermentation characteristics and reduce CH4 production, while the interactive effects were additionally observed. The BP could be a good phytonutrient source to modulate rumen fermentation. © 2022 Society of Chemical Industry.

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Abstract Background: Coffee hulls obtained from dry processing, have the potential to be used in ruminant diets. Objective: To evaluate the chemical composition and in situ degradability of dry matter (DM) and neutral detergent fiber (NDF) of coffee hulls treated with calcium oxide (CaO) in different environmental conditions (EC). Methods: Coffee hulls were subjected to treatments distributed in a 2 × 2 factorial arrangement, consisting of two levels of CaO (0 and 5%, on a DM basis) and two environmental conditions (aerobiosis and anaerobiosis) in a completely randomized design with four replicates, totaling sixteen experimental units. Five-gram samples were incubated in the rumen of two male cattle for 0, 3, 6, 9, 12, 24, 48, 72, 96, and 120 h. Results: Regarding dry matter degradation kinetic parameters, except for fraction b, the potential and effective degradability was affected (p<0.05) by a CaO × EC interaction. As for estimated fiber degradation parameters, the potentially degradable fraction b was affected (p<0.05) by CaO and EC. Treatment with CaO increased fraction b in 4.08 percentage points. Conclusions: The use of CaO in the treatment of coffee hulls increases the effective and potential degradability of DM and reduces the undegradable fiber fraction. Anaerobic condition is the best environment for the treatment of coffee hulls with CaO.

Resumen Antecedentes: la cáscara de café obtenida por procesamiento en seco presenta potencial de uso en la alimentación de rumiantes. Objetivo: Evaluar la composición química, la degradabilidad in situ de la materia seca (DM) y de la fibra detergente neutra (NDF) de la cascara de café tratada con óxido de calcio (CaO) en diferentes condiciones ambientales (EC). Métodos: la cáscara de café fue sometida a tratamientos distribuidos en un diseño factorial 2 x 2, dos dosis de CaO (0 a 5% en base seca), y dos condiciones ambientales (aeróbica y anaeróbica) en un diseño completamente al azar con cuatro repeticiones, totalizando dieciséis unidades experimentales. Las muestras de cinco gramos se incubaron en el rumen de dos bovinos machos durante 0, 3, 6, 9, 12, 24, 48, 72, 96 y 120 horas. Resultados: para los parámetros cinéticos de degradación de la DM, a excepción de la fracción b, la degradabilidad potencial y efectiva fueron afectadas (p<0,05) por la interacción CaO × EC. En cuanto a los parámetros estimados de la degradación de la fibra, la fracción potencialmente degradable b presentó efecto (p<0,05) para CaO y EC. El tratamiento con CaO promovió un aumento de la fracción b en 4,08 puntos porcentuales. Conclusión: la utilización del CaO para el tratamiento de la cáscara de café aumenta la degradabilidad efectiva y potencial de la DM y reducción de la fracción no degradable de la fibra. La condición de anaerobiosis se constituye en el mejor ambiente para el tratamiento de la cascara de café con CaO.

Resumo Antecedentes: cascas de café obtidas pelo processamento a seco têm potencial de serem usadas na alimentação de ruminantes. Objetivo: avaliar a composição química, a degradabilidade in situ da matéria seca (DM) e da fibra em detergente neutro (NDF) da casca de café tratada com óxido de cálcio (CaO) em diferentes condições de ambiente (EC). Métodos: a casca de café foi submetida aos tratamentos, distribuídos em esquema fatorial 2 × 2, sendo duas doses de CaO (0 e 5% base da matéria seca) e duas condições de ambiente (aeróbico e anaeróbico), em delineamento inteiramente casualizado, com quatro repetições, totalizando dezesseis unidades experimentais. Amostras de cinco gramas foram incubadas no rúmen de dois bovinos machos, nos tempos 0, 3, 6, 9, 12, 24, 48, 72, 96 e 120 horas. Resultados: para os parâmetros cinéticos de degradação da DM, à exceção da fração b, a degradabilidade potencial e efetiva foram afetados (p<0,05) pela interação CaO × EC. Quanto aos parâmetros estimados da degradação da fibra, a fração potencialmente degradável (b) apresentou efeito (p<0,05) para CaO e EC. O tratamento com CaO promoveu aumento da fração b em 4,08 pontos percentuais. Conclusões: a utilização do CaO no tratamento da casca de café promove aumento da degradabilidade efetiva e potencial da DM e redução da fração indegradável da fibra. A condição de anaerobiose constitui-se no melhor ambiente para o tratamento da casca de café com CaO.

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The study determined in vitro enteric methane (CH4) emission potential of whole-plant cereal (WPC) forages in relationship to nutrient composition, degradability, and rumen fermentation. Two varieties of each WPC (barley, oat, triticale, and wheat) were harvested from two field replications in each of two locations in central Alberta, Canada, and an in vitro batch culture technique was used to characterize gas production (GP), fermentation, and degradability. Starch concentration (g/kg dry matter (DM)) was least (p < 0.001) for oat (147), greatest for wheat (274) and barley (229), and intermediate for triticale (194). The aNDF concentration was greater for oat versus the other cereals (531 vs. 421 g/kg DM, p < 0.01). The 48 h DM and aNDF degradabilities (DMD and aNDFD) differed (p < 0.001) among the WPCs. The DMD was greatest for barley, intermediate for wheat and triticale, and least for oat (719, 677, 663, and 566 g/kg DM, respectively). Cumulative CH4 production (MP; mL) from 12 h to 48 h of incubation was less (p < 0.001) for oat than the other cereals, reflecting its lower DMD. However, CH4 yield (MY; mg of CH4/g DM degraded) of barley and oat grown at one location was less than that of wheat and triticale (28 vs. 31 mg CH4/g DM degraded). Chemical composition failed to explain variation in MY (p = 0.35), but it explained 45% of the variation in MP (p = 0.02). Variation in the CH4 emission potential of WPC was attributed to differences in DMD, aNDFD, and fermentation end-products (R2 ≥ 0.88; p < 001). The results indicate that feeding whole-plant oat forage to ruminants may decrease CH4 emissions, but animal performance may also be negatively affected due to lower degradability, whereas barley forage may ameliorate emissions without negative effects on animal performance.

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In situ rumen degradability of dry matter (DM) and crude protein (CP) in ruminant diets composed of graded inclusion levels of marula nut meal (MNM) as a protein source to replace soybean meal were evaluated. The five diets denoted as diet 1 (0.0 g kg-1 MNM: control), diet 2 (45.5 g kg-1 MNM), diet 3 (91.7 g kg-1 MNM), diet 4 (138.4 g kg-1 MNM), and diet 5 (185.9 g kg-1 MNM) were tested. Three cannulated mid-lactating Holstein cows were used to incubate triplicate subsamples of each diet for 2, 4, 8, 16, 24, and 48 h in polyester bags. The soluble fractions of DM and CP increased (P < 0.05) with increasing levels of MNM (138.4-185.9 g kg-1 MNM). However, the insoluble but degradable fractions of DM and CP increased (P < 0.05) with decreasing levels of MNM (45.5-0.0 g kg-1 and 91.7-0.0 g kg-1 MNM, respectively). While the degradation rate of fraction and the effective degradability of DM increased (P < 0.05) with decreasing levels of MNM (91.7-0.0 g kg-1), those of CP increased with increasing levels of MNM (138.4-185.9 g kg-1 MNM) in the diet. These results suggest that dietary inclusion of MNM up to 91.7 g kg-1 in ruminant diets can provide undegradable protein to be absorbed in the small intestines and used for metabolic function, while an inclusion of up to 185.9 g kg-1 can be degraded in the rumen for microbial protein synthesis.

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Guava leaves (Psidium guajava, GL), a high-phenolic- and flavonoid-containing plant resource capable of substituting the high-quality forage, may help in mitigating ruminal methane (CH4) emission without adverse impact on nutrient degradability if supplemented at an appropriate level. In order to test this hypothesis, rumen fermentation, CH4 production, and nutrient degradability of GL either solely or as a substitute of berseem hay (Trifolium alexandrinum, BH) were evaluated in a diet containing 50:50 concentrate to roughage. Five different levels of GL (0, 12.5, 25, 37.5, and 50%) were tested in vitro after 24 h incubation using a semi-automated gas production (GP) system. The current findings indicated that merely the presence of GL resulted in significantly lower values for cumulative GP (P < 0.001), CH4 emission (P < 0.05), truly degraded dry matter (TDDM; P < 0.001), truly degraded organic matter (TDOM; P < 0.001), and ammonia nitrogen (NH3-N) concentration (P < 0.001); however, pH (P < 0.001) and partitioning factor (P < 0.001) were higher. The total and individual volatile fatty acid (VFA) concentrations were drastically declined with GL as compared to BH (P < 0.05). A negative linear correlation was recorded between the levels of GL and GP including CH4 production (P < 0.05). The addition of GL up to 25% did not pose any negative effect on both TDDM and TDOM values along with NH3-N concentration. In addition, the inclusion of GL up to 25% did not affect the total or individual VFA concentration. Conclusively, in a medium concentrate diet, use of 25% GL and 25% BH in animal diet could be a promising alternative for mitigating the CH4 production without any deleterious effect on nutrient degradability.

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