• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.376-380
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• 2006

An experiment was conducted to study the effect of temperature and pH on in vitro nutrient degradability, volatile fatty acid profile and methane production. The fermenter used was the semi-continuous system, known as the rumen simulation technique (RUSITEC). Sixteen cylinders were used at one time with a volume of 800 ml, the dilution rate was set at 3.5%/hour, the infused buffer being McDougall's artificial saliva. Basal diet (9.6 g DM) used in RUSITEC consisted of (DM) 6.40 g Timothy hay, 1.86 g crushed corn and 1.34 g soybean meal. The food for the fermentation vessel was provided in nylon bags, which were gently agitated in the liquid phase. The experiment lasted for 17 d with all the samples taken during the last 5 d. Treatments were allocated at random to four vessels each and were (1) two temperature levels of $39^{\circ}C$ and $41^{\circ}C$ (2) two pH levels of 6.0 and 7.0. The total diet contained ($g\;kg^{-1}$ DM) 957 OM, 115 CP and $167MJ\;kg^{-1}$ (DM) GE. Although increase in temperature from $39^{\circ}C$ to $41^{\circ}C$ reduced degradation of major nutrients in vitro, it was non-significant. Interaction effect of temperature with pH also reflected a similar trend. However, pH showed a significant (p<0.05) negative effect on the degradability of all the nutrients in vitro. Altering the in vitro pH from 7 to 6 caused marked reduction in DMD from 60.2 to 41.8, CPD from 76.3 to 55.3 and GED from 55.3 to 35.1, respectively. Low pH (6) depressed total VFA production (61.9 vs. 34.9 mM) as well as acetate to propionate ratio in vitro (from 2.0 to 1.5) when compared to pH 7. Compared to pH 7, total gas production decreased from 1,841 ml to 1,148 ml at pH 6, $CO_2$ and $CH_4$ production also reduced from 639 to 260 ml and 138 to 45 ml, respectively. This study supported the premise that pH is one of the principal factors affecting the microbial production of volatile fatty acids and gas. Regulating the ruminal pH to increase bacterial activity may be one of the methods to optimize VFA production, reduce methane and, possibly, improve animal performance.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.4
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• pp.543-549
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• 2007

Two experiments were conducted to investigate the effects of disodium fumarate on the in vitro rumen fermentation profiles of different substrates and microbial communities. In experiment 1, nine diets (high-forage diet (forage:concentrate, e.g. F:C = 7:3, DM basis), medium-forage diet (F:C = 5:5, DM basis), low-forage diet(F:C = 1:9, DM basis), cracked corn, cracked wheat, soluble starch, tall elata (Festuca elata), perennial ryegrass and rice straw) were fermented in vitro by rumen microorganisms from local goats. The results showed that during 24 h incubations, for all substrates, disodium fumarate increased (p<0.05) the gas production, and tended to increase (p<0.10) the acetate, propionate and total VFA concentration and decrease the ratio of acetate to propionate, whereas no treatment effect was observed for the lactate concentration. The apparent DM loss for tall elata, perennial ryegrass and rice straw increased (p<0.05) with the addition of disodium fumarate. With the exception of tall elata, perennial ryegrass and rice straw, disodium fumarate addition increased the final pH (p<0.05) for all substrates. In experiment 2, three substrates (a high-forage diet, a medium-forage diet and a high concentrate diet) were fermented by mixed rumen microbes in vitro. A polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique was applied to compare microbial DNA fingerprints between substrates at the end of 24 h incubation. The results showed that when Festuca elata was used as substrate, the control and disodium fumarate treatments had similar DGGE profiles, with their similarities higher than 96%. As the ratio of concentrate increased, however, the similarities in DGGE profiles decreased between the control and disodium fumarate treatment. Overall, these results suggest that disodium fumarate is effective in increasing the pH and gas production for the diets differing in forage: concentrate ratio, grain cereals and soluble starch, and in increasing dry matter loss for the forages (tall elata, perennial ryegrass and rice straw) in vitro, whereas its effect on changes of ruminal microbial community may largely depend on the general nature of the substrate.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.2
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• pp.295-302
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• 2011

Almost half of New Zealand's greenhouse gas emissions arise from agriculture and enteric methane ($CH_4 $) emissions arising from ruminant animals constitute 30% of total $CO_2$-e emissions. Enteric $CH_4$ emissions have increased by 9% since 1990. Extensive research has been undertaken to develop reliable methods for measuring enteric $CH_4$ emissions. New Zealand studies using the SF6 tracer technique suggest that on average this technique yields similar values to the 'gold' standard of calorimetry, but with a larger variance. National inventory estimates based on results obtained using the $SF_6$ technique will therefore overestimate the uncertainty. Mitigating emissions can be achieved by changing feed type but there are practical and cost barriers to the use of alternative feeds. Forages containing condensed tannins do reduce emissions but are agronomically inferior to the forages currently used. Rumen additives have shown some success in-vitro but results from in-vivo trials with both monensin and fumaric acid have been disappointing. The development of methods for directly manipulating rumen microorganisms are at an early stage and work to develop vaccines that can inhibit methanogenesis has yielded mixed results. The successful identification of sheep with contrasting $CH_4$ yields raises the possibility that, in the long term, a breeding approach to $CH_4$ mitigation is feasible.

• Animal Bioscience
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• v.34 no.10
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• pp.1607-1615
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• 2021

Objective: Chaya (Cnidoscolus aconitifolius) leaf has been found to be an important source of protein, vitamins, minerals, as well as phytonutrients. The present study aimed to evaluate the effect of Chaya leaf pellet (CHYP) with various level of crude protein (CP) in the concentrate on rumen fermentation characteristics and nutrient degradability in in vitro gas production technique. Methods: In an in vitro rumen fermentation study the dietary treatments were arranged according to a 3×5 factorial arrangement in a completely randomized design, consisting of Factor A: three levels of CP of concentrate mixtures (14%, 16%, and 18% CP, respectively) and Factor B: five levels of CHYP supplementation (at 0%, 2%, 4%, 6%, and 8% of dry matter substrates). Results: The gas production kinetics, fraction (a) and fraction (b) were lower (p<0.05) with an increasing CHYP addition. Additionally, the fraction (a+b) was found to yield a significant interaction (p<0.05) while the fraction (c) was not impacted by CHYP addition. However, in vitro DM degradability was enhanced and interactive (p<0.05), using 16% CP of concentrate with 6% and 8% CHYP, when compared with 18% CP in the non-addition. Additionally, the treatment with higher CP of the concentrate was higher in NH₃-N concentration (p<0.001) and by CHYP supplementation group (p<0.05). Nevertheless, protozoal counts in the rumen were remarkably decreased (p<0.05) with increasing level of CHYP supplementation. Furthermore, rumen C₂ concentration was lower (p<0.05) in the treatments with CHYP supplementation, while C₃ was significantly increased and interactive (p<0.05) between levels of CP and CHYP supplementation especially at 8% CHYP supplementation. Conclusion: Based on this study, the results revealed CHYP as a promising feed supplement to enhance rumen fermentation and to mitigate methane production. However, in vivo feeding experiments should be subsequently conducted to elucidate the effect of CHYP supplementation on rumen fermentation, as well as ruminant production efficiency.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.5
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• pp.653-658
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• 2012

This study was conducted to estimate the potential acid production value (PAPV) of major diets and to determine the relationship between dietary PAPV and dairy production traits. Estimation of PAPV of major cattle feeds was based on an in vitro technique, which determined the degree of Ca dissociation from $CaCO_3$. Data on feeds and production traits were collected on 744 multiparous lactating Holstein dairy cows from five different farms. Grains had high PAPV with variable protein sources and by-products. High PAPV feedstuffs had a higher total gas production and lower pH compared to those with low PAPV. Dietary PAPV had a positive correlation with intake of dry matter, NDF, ADF, milk yield and milk solid production but a negative correlation with milk protein and milk fat concentration. Current results indicate that dietary PAPV can be utilized in predicting dairy production traits.

• Journal of Animal Science and Technology
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• v.63 no.5
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• pp.1018-1033
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• 2021

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.

• Journal of Animal Science and Technology
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• v.47 no.4
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• pp.615-624
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• 2005

The cPCR technique was used to monitor rumen fermentation and attachment of Fibrobacter succinogenes to cellulose at different pH in the in vitro culture medium. The target fragments of 16S rDNA(445 bp) were amplified from genomic DNA of F. succinogenes with specific primers and internal controls(205 bp) were constructed. Cell counts were estimated from the amounts of genomic DNA, which was calculated from cPCR results. F. succinogenes in pH 6.8 and 6.2 showed apparently higher attachment than in pH 5.8 during all incubation time. There were some difference between pH 6.8 and 6.2 in the degree of attachment, but the different was not significant (P>0.05). Cellulose degradation increased in process of incubation time and the increasing rate was higher when initial pH was higher. The pH in culture medium decreased regardless of initial pH in course of incubation time. After 24 h of incubation, medium pH was dropped by 0.24, 0.58 and 0.16 units from original medium pH 6.8, 6.2 and 5.8, respectively. More gas was produced at higher initial pH in the same manner as in cellulose degradation. In summery, Initial pH of rumen culture in vitro significantly influenced cellulose digestion, gas production, pH change and bacterial attachment. Especially, low pH(5.8) resulted in much lower bacterial attachment and fiber digestion compared to higher medium pH.