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Research Article
Wenzhu Yang
Research Centre, Agriculture and Agri-food Canada, Lethbridge, Alberta, Canada
Corresponding Author
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Background
The objectives of this study were to determine the effect of commercial slow-release urea (SRU) on in vitro fermentation characteristics, nutrient digestibility, gas production, microbial protein synthesis and bacterial community using rumen simulation technique (RUSITEC). The experiment was a completely randomized design with four treatments and four replications of each treatment. Treatments were: control diet (no SRU addition), control diet plus 0.28% SRU (U28), or plus 0.56% SRU (U56), and control diet that was modified for substituting with 0.35% SRU for equavelant soybean protein (MU35; dry matter [DM] basis). The experiment consisted of 8 days of adaptation and 7 days of data and sample collection. Rumen inoculum was obtained from three ruminally fistulated Angus cows fed the same diet to the substrate incubated.
Results
Digestibility of DM, organic matter (OM), crude protein (CP), fibre and starch was not affected, but daily production of gas (P < 0.07) and methane (P < 0.05) was quadratically changed with increasing SRU supplementation. The increase of SRU addition did not affect fermentation pH and total volatile fatty acid (VFA) production, whereas linearly (P < 0.01) decreased proportion of propionate, and linearly (P < 0.01) increased acetate to propionate ratio and ammonia nitrogen (N) concentration. The microbial N efficiency also linearly (P < 0.03) improved with increasing supplementation of SRU. In comparison with control diet, the dietary substitution of SRU for part of soybean meal increased (P < 0.05) the digestibility of DM, OM and CP and decreased (P < 0.02) the total gas production. The total VFA production and acetate to propionate ratio did not differ between control and MU35, whereas the proportion of butyrate was lower (P < 0.05) and that of branched-chain VFA was greater (P < 0.05) with MU35 than control diet. Total and liquid-associated microbial N production as well as ammonia N concentration were greater (P < 0.03) with MU35 than control diet. Observed OTUs, Shannon diversity index, and beta diversity of the microbial community did not differ among treatments. Taxonomic analysis revealed no effect of adding SRU on the relative abundance of bacteria at the phylum level, while at the genus level, the impact of SRU addition on microbial community was greater with MU35 either for liquid associate bacteria or feed particle-associated bacteria.
Conclusions
Supplementation of a dairy cow diet with SRU showed potential of increase in ammonia N concentration and microbial protein production, and change fermentation pattern to more acetate production. Adding SRU in dairy cow diet also showed beneficial effect on improving digestibility of OM and fibre. The results suggest that SRU can partially substitute soybean meal in dairy cow diet to increase microbial protein production without impairing rumen fermentation.
Keywords
Slow-release urea, Dairy cow diet, Fermentation characteristics, Artificial rumen system
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CURRENT STATUS: Under Review
Version 1
Posted 29 Oct, 2021
No community comments so far
Review #2 received
Received 11 Nov, 2021
Review #1 received
Received 10 Nov, 2021
Reviewer #2 agreed
On 03 Nov, 2021
Reviews received
Received 01 Nov, 2021
Reviewer #1 agreed
On 31 Oct, 2021
Reviewers invited
Invitations sent on 28 Oct, 2021
Editor assigned
On 26 Oct, 2021
Submission checks complete
On 25 Oct, 2021
Editor invited
On 25 Oct, 2021
First submitted
On 25 Oct, 2021
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This preprint is under consideration at Journal of Animal Science and Biotechnology. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research Article
Wenzhu Yang
Research Centre, Agriculture and Agri-food Canada, Lethbridge, Alberta, Canada
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 1
Posted 29 Oct, 2021
No community comments so far
Review #2 received
Received 11 Nov, 2021
Review #1 received
Received 10 Nov, 2021
Reviewer #2 agreed
On 03 Nov, 2021
Reviews received
Received 01 Nov, 2021
Reviewer #1 agreed
On 31 Oct, 2021
Reviewers invited
Invitations sent on 28 Oct, 2021
Editor assigned
On 26 Oct, 2021
Submission checks complete
On 25 Oct, 2021
Editor invited
On 25 Oct, 2021
First submitted
On 25 Oct, 2021
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background
The objectives of this study were to determine the effect of commercial slow-release urea (SRU) on in vitro fermentation characteristics, nutrient digestibility, gas production, microbial protein synthesis and bacterial community using rumen simulation technique (RUSITEC). The experiment was a completely randomized design with four treatments and four replications of each treatment. Treatments were: control diet (no SRU addition), control diet plus 0.28% SRU (U28), or plus 0.56% SRU (U56), and control diet that was modified for substituting with 0.35% SRU for equavelant soybean protein (MU35; dry matter [DM] basis). The experiment consisted of 8 days of adaptation and 7 days of data and sample collection. Rumen inoculum was obtained from three ruminally fistulated Angus cows fed the same diet to the substrate incubated.
Results
Digestibility of DM, organic matter (OM), crude protein (CP), fibre and starch was not affected, but daily production of gas (P < 0.07) and methane (P < 0.05) was quadratically changed with increasing SRU supplementation. The increase of SRU addition did not affect fermentation pH and total volatile fatty acid (VFA) production, whereas linearly (P < 0.01) decreased proportion of propionate, and linearly (P < 0.01) increased acetate to propionate ratio and ammonia nitrogen (N) concentration. The microbial N efficiency also linearly (P < 0.03) improved with increasing supplementation of SRU. In comparison with control diet, the dietary substitution of SRU for part of soybean meal increased (P < 0.05) the digestibility of DM, OM and CP and decreased (P < 0.02) the total gas production. The total VFA production and acetate to propionate ratio did not differ between control and MU35, whereas the proportion of butyrate was lower (P < 0.05) and that of branched-chain VFA was greater (P < 0.05) with MU35 than control diet. Total and liquid-associated microbial N production as well as ammonia N concentration were greater (P < 0.03) with MU35 than control diet. Observed OTUs, Shannon diversity index, and beta diversity of the microbial community did not differ among treatments. Taxonomic analysis revealed no effect of adding SRU on the relative abundance of bacteria at the phylum level, while at the genus level, the impact of SRU addition on microbial community was greater with MU35 either for liquid associate bacteria or feed particle-associated bacteria.
Conclusions
Supplementation of a dairy cow diet with SRU showed potential of increase in ammonia N concentration and microbial protein production, and change fermentation pattern to more acetate production. Adding SRU in dairy cow diet also showed beneficial effect on improving digestibility of OM and fibre. The results suggest that SRU can partially substitute soybean meal in dairy cow diet to increase microbial protein production without impairing rumen fermentation.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
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