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Mohapatra A, Trivedi S, Kolte AP, Tejpal CS, Elavarasan K, Vaswani S, Malik PK, Ravishankar CN, Bhatta R. Effect of Padina gymnospora biowaste inclusion on in vitro methane production, feed fermentation, and microbial diversity. Front Microbiol 2024; 15:1431131. [PMID: 39027100 PMCID: PMC11254855 DOI: 10.3389/fmicb.2024.1431131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 06/19/2024] [Indexed: 07/20/2024] Open
Abstract
In vitro studies were undertaken aiming to study the methane (CH4) mitigation potential of biowaste (BW) of Padina gymnospora at the graded inclusion of 0% (C), 2% (A2), 5% (A5), and 10% (A10) of the diet composed of straw and concentrate in 40:60 ratio. The chemical composition analysis revealed that the BW contained higher crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and ether extract (EE) than the PF (fresh seaweed, P. gymnospora). The concentration of cinnamic acid, sinapic acid, kaempferol, fisetin p-coumaric acid, ellagic acid, and luteolin in BW was 1.5-6-folds less than the PF. Inclusion of BW decreased (P < 0.0001) CH4 production by 34%, 38%, and 45% in A2, A5, and A10 treatments, respectively. A decrease (P < 0.0001) of 7.5%-8% in dry matter (DM) and organic matter (OM) digestibility was also recorded with the BW supplementation. The BW inclusion also decreased the numbers of total (P = 0.007), Entodinomorphs (P = 0.011), and Holotrichs (P = 0.004) protozoa. Metagenome data revealed the dominance of Bacteroidetes, Proteobacteria, Firmicutes, Actinobacteria, and Fibrobacter microbial phyla. At the phylum level, Euryarchaeota dominated the archaeal community, whereas Methanobrevibacter was most abundant at the genus level. It can be concluded that the inclusion of BW in straw and concentrate based diet by affecting rumen fermentation, protozoal numbers, and compositional shift in the archaeal community significantly decreased CH4 production. Utilization of biowaste of P. gymnospora as a CH4 mitigating agent will ensure its efficient utilization rather than dumping, which shall cause environmental pollution and health hazards.
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Affiliation(s)
- Archit Mohapatra
- Indian Council of Agricultural Research (ICAR)-National Institute of Animal Nutrition and Physiology, Bengaluru, India
- School of Sciences, JAIN (Deemed-to-be-University), Bengaluru, India
| | - Shraddha Trivedi
- Indian Council of Agricultural Research (ICAR)-National Institute of Animal Nutrition and Physiology, Bengaluru, India
| | - Atul P. Kolte
- Indian Council of Agricultural Research (ICAR)-National Institute of Animal Nutrition and Physiology, Bengaluru, India
| | - Chaluvanahalli S. Tejpal
- Indian Council of Agricultural Research (ICAR)-Central Institute of Fisheries Technology, Kochi, India
| | - Krishnamoorthy Elavarasan
- Indian Council of Agricultural Research (ICAR)-Central Institute of Fisheries Technology, Kochi, India
| | - Shalini Vaswani
- Uttar Pradesh Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya Evam Go-Anusandhan Sansthan, Mathura, India
| | - Pradeep Kumar Malik
- Indian Council of Agricultural Research (ICAR)-National Institute of Animal Nutrition and Physiology, Bengaluru, India
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Kharazian ZA, Xu D, Su R, Guo X. Effects of inoculation and dry matter content on microbiome dynamics and metabolome profiling of sorghum silage. Appl Microbiol Biotechnol 2024; 108:257. [PMID: 38456919 PMCID: PMC10923742 DOI: 10.1007/s00253-024-13096-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/22/2024] [Accepted: 02/28/2024] [Indexed: 03/09/2024]
Abstract
Sorghum forage was ensiled for 90 days at two dry matter (DM) contents (27 vs. 39%) without or with Lactiplantibacillus plantarum inoculation. On day 90 of fermentation, silages were sampled to assess the microbial community dynamics and metabolome profile. L. plantarum inoculation improved silage quality, as shown by a lower pH and greater acetic acid concentration. Loss of DM remained unaffected by L. plantarum inoculation but was greater in low- vs. high-DM sorghum silages (14.4 vs. 6.62%). The microbiome analysis revealed that Pseudomonas congelans represented the dominant species of the epiphytic microbiota in both low- and high-DM sorghum forage before ensiling. However, L. buchneri represented the dominant species at the end of ensiling. Ensiling fermentation resulted in distinct metabolic changes in silages with varying DM content. In low-DM silages, ensiling fermentation led to the accumulation of 24 metabolites and a reduction in the relative concentration of 13 metabolites. In high-DM silages, ensiling fermentation resulted in an increase in the relative concentration of 26 metabolites but a decrease in the concentration of 8 metabolites. Compared to non-inoculated silages, L. plantarum inoculation resulted in an increased concentration of 3 metabolites and a reduced concentration of 5 metabolites in low-DM silages. Similarly, in high-DM silages, there was an elevation in the relative concentration of 3 metabolites, while a decrease in 7 other metabolites. Ten metabolites with bio-functional activity were identified, including chrysoeriol, isorhamnetin, petunidin 3-glucoside, apigenin, caffeic acid, gallic acid, p-coumaric acid, trans-cinnamic acid, herniarin, and 3,4-dihydroxy-trans-cinnamate. This study presents a comprehensive analysis of microbiome and metabolome profiling of sorghum forage during ensiling as a function of DM content and L. plantarum inoculation, with a particular emphasis on identifying metabolites that may possess bio-functional properties. KEY POINTS: • DM loss was not different by L. plantarum but higher in low- vs. high-DM silage. • L. buchneri dominated ensiling, regardless of DM level. • 10 metabolites with bio-functional activity were identified.
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Affiliation(s)
- Zohreh Akhavan Kharazian
- State Key Laboratory of Grassland and Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
- Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou, 730000, China
| | - Dongmei Xu
- State Key Laboratory of Grassland and Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
- Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou, 730000, China
| | - Rina Su
- State Key Laboratory of Grassland and Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
- Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou, 730000, China
| | - Xusheng Guo
- State Key Laboratory of Grassland and Agro-Ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
- Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou, 730000, China.
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Gao Q, Liu H, Wang Z, Lan X, An J, Shen W, Wan F. Recent advances in feed and nutrition of beef cattle in China - A review. Anim Biosci 2023; 36:529-539. [PMID: 36108687 PMCID: PMC9996267 DOI: 10.5713/ab.22.0192] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/10/2022] [Indexed: 11/27/2022] Open
Abstract
The beef cattle industry in China has advanced remarkably since its reform and opening up; consequently, China has become the world's third-largest beef cattle producer. China is also one of the countries with the most substantial research input and output in the field of beef cattle feed and nutrition. The progress and innovation by China in the research field of beef cattle feed and nutrition have undoubtedly promoted the development of the domestic beef cattle industry. This review summarizes recent advances in feed resource development, nutrient requirements, and nutritional regulation of beef cattle in China. Limitations in current research and perspectives on future work are also discussed.
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Affiliation(s)
- Qian Gao
- College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Hu Liu
- State Key Laboratory of Grassland Agro-Ecosystems; College of Ecology, Lanzhou University, Lanzhou, 730000, China
| | - Zuo Wang
- College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Xinyi Lan
- College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Jishan An
- College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Weijun Shen
- College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Fachun Wan
- College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China
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Ibrahim TA, Hassen A, Apostolides Z. The Antimethanogenic Potentials of Plant Extracts: Their Yields and Phytochemical Compositions as Affected by Extractive Solvents. PLANTS (BASEL, SWITZERLAND) 2022; 11:3296. [PMID: 36501339 PMCID: PMC9737672 DOI: 10.3390/plants11233296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
Plant phytochemicals are an important area of study in ruminant nutrition, primarily due to their antimethanogenic potentials. Plant extract yields, their bioactive compounds and antimethanogenic properties are largely dependent on the nature of the extractive solvents. This study evaluated the yields and phytochemical constituents of four plant extracts, as affected by the aqueous-methanolic (H2O-CH3OH) extraction and their antimethanogenic properties on the in vitro methane production. The plant extracts included Aloe vera, Jatropha curcas, Moringa oleifera, and Piper betle leaves with three levels of extractions (70, 85, and 100% CH3OH). The crude plant extract yields increased with the increasing amount of water. M. oleifera crude extracts yields (g/10 g) increased from 3.24 to 3.92, A. vera, (2.35 to 3.11) J. curcas (1.77 to 2.26), and P. betle (2.42 to 3.53). However, the identified and quantified metabolites showed differing degrees of solubility unique to their plant leaves in which they exist, while some of the metabolites were unaffected by the extraction solvents. The methane mitigating potentials of these extracts were evaluated as additives on Eragrostis curvula hay at a recommended rate of 50 mg kg−1 DM. The plant extracts exhibited antimethanogenic properties to various degrees, reducing (p < 0.05) in vitro methane production in the tested hay, A. vera, J. curcas, M. oleifera and P. betle reduced methane emission by 6.37−7.55%, 8.02−11.56%, 12.26−12.97, and 5.66−7.78 respectively compared to the control treatment. However, the antimethanogenic efficacy, gas production and organic matter digestibility of the plant extracts were unaffected by the extraction solvents. Metabolites, such as aloin A, aloin B and kaempferol (in A. vera), apigenin, catechin, epicatechin, kaempferol, tryptophan, procyanidins, vitexin-7-olate and isovitexin-7-olate (in J. curcas), alkaloid, kaempferol, quercetin, rutin and neochlorogenic acid (in M. oleifera) and apigenin-7,4′-diglucoside, 3-p-coumaroylquinic acid, rutin, 2-methoxy-4-vinylphenol, dihydrocaffeic acid, and dihydrocoumaric acid (in P. betle) exhibited a methane reducing potential and hence, additional studies may be conducted to test the methane reducing properties of the individual metabolites as well as their combined forms. Plant extracts could be more promising, and hence, further study is necessary to explore other extraction methods, as well as the encapsulation of extracts for the improved delivery of core materials to the target sites and to enhance methane reducing properties. Furthermore, the use of 70% aqueous extraction on M. oleifera leaf is recommended for practical use due to the reduced cost of extractive solvents, the lower cost and availability of Moringa plants in South Africa, especially in Gauteng Province. Furthermore, 70% aqueous-methanolic extractions of A. vera, J. curcas, and P. betle are recommended for practical use in regions where they exist in abundance and are cost effective.
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Affiliation(s)
- Taofik Adam Ibrahim
- Department of Animal Sciences, University of Pretoria, Pretoria 0028, South Africa
| | - Abubeker Hassen
- Department of Animal Sciences, University of Pretoria, Pretoria 0028, South Africa
| | - Zeno Apostolides
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0028, South Africa
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Pena-Bermudez YA, Vincenzi R, Meo-Filho P, Sakamoto LS, Lobo R, Benetel G, Lobo A, Matos C, Benetel V, Lima CG, Berndt A, Cardenas LM, Bueno ICS. Effect of Yerba Mate Extract as Feed Additive on Ruminal Fermentation and Methane Emissions in Beef Cattle. Animals (Basel) 2022; 12:2997. [PMID: 36359122 PMCID: PMC9658154 DOI: 10.3390/ani12212997] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 09/19/2023] Open
Abstract
The inclusion of plant extracts that contain secondary compounds with the potential to modulate rumen fermentation and improve animal performance has gained attention in recent years. The aim of this study was to evaluate the effect of the inclusion of yerba mate extract (Ilex paraguariensis ST. Hilaire) (YME) on the ruminal parameters. Eight castrated cattle were divided into four groups, a control without YME (0%) and three treatment groups with 0.5, 1 and 2% inclusion of YME in the dry matter. The inclusion of YME did not show differences in ruminal methane emissions (CH4), and total apparent digestibility (p = 0.54). Likewise, YME did not modify ruminal pH, but positively affected NH3-N, which decreased linearly as the extract level in the diet increased (p = 0.01). No short chain fatty acids (SCFA) were influenced by YME, except isovaleric acid (p = 0.01), which showed a lower concentration in the inclusion of 2% YME. Our results show that up to 2% YME does not affect digestibility, ruminal fermentation parameters, or the concentration of short-chain fatty acids in the rumen.
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Affiliation(s)
- Yuli A. Pena-Bermudez
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
| | - Rafaela Vincenzi
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
| | - Paulo Meo-Filho
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
- Net Zero and Resilient Farming, Rothamsted Research–North Wyke. North Wyke, Okehampton, Devon EX20 2SB, UK
| | | | - Richard Lobo
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
- Department of Animal Science, Institute of Food and Agricultural Sciences, University of Florida, 2250 Shealy Dr, Gainesville, FL 32608, USA
| | - Gabriela Benetel
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
| | - Annelise Lobo
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
| | - Carol Matos
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
| | - Vanderlei Benetel
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
| | - Cesar G. Lima
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
| | - Alexandre Berndt
- Brazilian Agricultural Research Corporation (EMBRAPA), Embrapa–Southeast Livestock, São Carlos 13560-970, SP, Brazil
| | - Laura M. Cardenas
- Net Zero and Resilient Farming, Rothamsted Research–North Wyke. North Wyke, Okehampton, Devon EX20 2SB, UK
| | - Ives C. S. Bueno
- Department of Animal Science, Faculty of Animal Science and Food Engineering, University of Sao Paulo (USP), Pirassununga 13635-900, SP, Brazil
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Liu H, Li Z, Pei C, Degen A, Hao L, Cao X, Liu H, Zhou J, Long R. A comparison between yaks and Qaidam cattle in in vitro rumen fermentation, methane emission, and bacterial community composition with poor quality substrate. Anim Feed Sci Technol 2022. [DOI: 10.1016/j.anifeedsci.2022.115395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Samal L, Kumar Dash S. Nutritional Interventions to Reduce Methane Emissions in Ruminants. Vet Med Sci 2022. [DOI: 10.5772/intechopen.101763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Methane is the single largest source of anthropogenic greenhouse gases produced in ruminants. As global warming is a main concern, the interest in mitigation strategies for ruminant derived methane has strongly increased over the last years. Methane is a natural by-product of anaerobic microbial (bacteria, archaea, protozoa, and fungi) fermentation of carbohydrates and, to a lesser extent, amino acids in the rumen. This gaseous compound is the most prominent hydrogen sink product synthesized in the rumen. It is formed by the archaea, the so-called methanogens, which utilize excessive ruminal hydrogen. Different nutritional strategies to reduce methane production in ruminants have been investigated such as dietary manipulations, plant extracts, lipids and lipid by-products, plant secondary metabolites, flavonoids, phenolic acid, statins, prebiotics, probiotics, etc. With the range of technical options suggested above, it is possible to develop best nutritional strategies to reduce the ill effects of livestock on global warming. These nutritional strategies seem to be the most developed means in mitigating methane from enteric fermentation in ruminants and some are ready to be applied in the field at the moment.
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Bharanidharan R, Thirugnanasambantham K, Ibidhi R, Baik M, Kim TH, Lee Y, Kim KH. Metabolite Profile, Ruminal Methane Reduction, and Microbiome Modulating Potential of Seeds of Pharbitis nil. Front Microbiol 2022; 13:892605. [PMID: 35615517 PMCID: PMC9125194 DOI: 10.3389/fmicb.2022.892605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
We identified metabolites in the seeds of Pharbitis nil (PA) and evaluated their effects on rumen methanogenesis, fiber digestibility, and the rumen microbiome in vitro and in sacco. Four rumen-cannulated Holstein steers (mean body weight 507 ± 32 kg) were used as inoculum donor for in vitro trial and live continuous culture system for in sacco trial. PA was tested in vitro at doses ranging from 4.5 to 45.2% dry matter (DM) substrate. The in sacco trial was divided into three phases: a control phase of 10 days without nylon bags containing PA in the rumen, a treatment phase of 11 days in which nylon bags containing PA (180 g) were placed in the rumen, and a recovery phase of 10 days after removing the PA-containing bags from the rumen. Rumen headspace gas and rumen fluid samples were collected directly from the rumen. PA is enriched in polyunsaturated fatty acids dominated by linoleic acid (C18:2) and flavonoids such as chlorogenate, quercetin, quercetin-3-O-glucoside, and quinic acid derivatives. PA decreased (p < 0.001) methane (CH4) production linearly in vitro with a reduction of 24% at doses as low as 4.5% DM substrate. A quadratic increase (p = 0.078) in neutral detergent fiber digestibility was also noted, demonstrating that doses < 9% DM were optimal for simultaneously enhancing digestibility and CH4 reduction. In sacco, a 50% decrease (p = 0.087) in CH4 coupled with an increase in propionate suggested increased biohydrogenation in the treatment phase. A decrease (p < 0.005) in ruminal ammonia nitrogen (NH3-N) was also noted with PA in the rumen. Analysis of the rumen microbiome revealed a decrease (p < 0.001) in the Bacteroidetes-to-Firmicutes ratio, suggesting PA to have antiprotozoal potential. At the genus level, a 78% decrease in Prevotella spp. and a moderate increase in fibrolytic Ruminococcus spp. were noted in the treatment phase. In silico binding of PA metabolites to cyclic GMP-dependent protein kinase of Entodinium caudatum supported the antiprotozoal effect of PA. Overall, based on its high nutrient value and antiprotozoal activity, PA could probably replace the ionophores used for CH4 abatement in the livestock industry.
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Affiliation(s)
- Rajaraman Bharanidharan
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Krishnaraj Thirugnanasambantham
- Department of Ecofriendly Livestock Science, Institutes of Green-Bio Science and Technology, Seoul National University, Pyeongchang, South Korea
- Pondicherry Centre for Biological Science and Educational Trust, Villupuram, India
- Department of Biotechnology, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai, India
| | - Ridha Ibidhi
- Department of Ecofriendly Livestock Science, Institutes of Green-Bio Science and Technology, Seoul National University, Pyeongchang, South Korea
| | - Myunggi Baik
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Tae Hoon Kim
- Department of International Agricultural Technology, Graduate School of International Agricultural Technology, Seoul National University, Pyeongchang, South Korea
| | - Yookyung Lee
- National Institute of Animal Sciences, Rural Development Administration, Jeonju, South Korea
| | - Kyoung Hoon Kim
- Department of Ecofriendly Livestock Science, Institutes of Green-Bio Science and Technology, Seoul National University, Pyeongchang, South Korea
- Department of International Agricultural Technology, Graduate School of International Agricultural Technology, Seoul National University, Pyeongchang, South Korea
- *Correspondence: Kyoung Hoon Kim,
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Rumen Bacterial Community of Grazing Lactating Yaks ( Poephagus grunniens) Supplemented with Concentrate Feed and/or Rumen-Protected Lysine and Methionine. Animals (Basel) 2021; 11:ani11082425. [PMID: 34438881 PMCID: PMC8388701 DOI: 10.3390/ani11082425] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/12/2021] [Accepted: 08/12/2021] [Indexed: 12/17/2022] Open
Abstract
Simple Summary Ruminal microorganisms, especially bacteria, play a vital role in utilizing fibrous material in ruminants. The yak is a bovid on the Qinghai-Tibet Plateau that traditionally only grazes natural pasture all year. During lactation, energy intake of yaks is often well below requirements, and yaks lose body weight. Today, to mitigate body weight losses during lactation, suckling yaks are often offered supplementary feed. This study examined the effect of dietary supplements on rumen bacteria in lactating yak. The yaks were offered supplementary concentrate feed (C), rumen-protected Lys and Met (RPA), or both (RPA+C). The ratio of the relative abundance of Firmicutes to Bacteroidetes in RPA+C was greater than in the RPA group, while there was no difference between C and RPA+C. The intakes of supplements resulted in a number of alterations in the abundances of bacteria at the genus level. When supplemented with C, yaks increased the concentration of ruminal total volatile fatty acids (VFAs), acetate, and butyrate. These results demonstrate that supplementary feed: (1) alters the composition of rumen microbiota and VFAs of lactating yaks; and (2) can be used to manipulate the composition of rumen microbiota. Abstract Traditionally, yaks graze only natural pasture all year round without supplements. Forage intake of lactating yaks is below energy and protein requirements, even in the summer, and suckling yaks lose a substantial amount of significant body weight. Today, to mitigate the loss in body weight, supplementary feed is being offered to lactating yaks. However, the effects of supplementary feed on ruminal bacterial communities in lactating yaks is unknown. In the current study, we examined the effect of supplementary feed on ruminal microbiota, using 16S rRNA sequencing, and on volatile fatty acids (VFAs). Twenty-four lactating yaks of similar body weight (218 ± 19.5 kg) and grazing natural pasture were divided randomly into four groups and received different supplements: (1) rumen-protected amino acids (RPA); (2) concentrate feed (C); (3) RPA plus C (RPA+C); and (4) no supplements (control-CON). The concentrations of total VFAs, acetate, and butyrate were greater (p < 0.05) when supplemented with concentrate feed (C and RPA+C) than without concentrate feed (CON and RPA). Bacteroidetes (B) and Firmicutes (F) were the dominant ruminal bacterial phyla in all groups. The ratio of relative abundance of F:B in RPA+C was greater than in the RPA group, while there was no difference between CON and RPC (interaction, p = 0.026). At the genus level, the relative abundances of Absconditabacteriales_SR1, Bacteroidales-RF16-group, Bacteroidales_BS11_gut_group, Prevotellaceae, and Rikenellaceae_RC9_gut_group were lesser (p < 0.05) with supplementary concentrate feed (C and RPA+C) than without concentrate feed (CON and RPA), whereas Butyrivibrio_2 and Pseudobutyrivibrio were greater (p < 0.05) with supplementary rumen-protected amino acids (RPA and RPA+C) than without rumen-protected amino acids (CON and C). These results demonstrate that supplementary feed: (1) alters the composition of rumen microbiota and concentrations of ruminal VFAs in lactating yaks; and (2) can be used to manipulate the composition of rumen microbiota.
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