{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T15:58:22Z","timestamp":1785513502984,"version":"3.56.0"},"reference-count":49,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T00:00:00Z","timestamp":1785456000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Key Research and Development Program Project of Xinjiang Uygur Autonomous Region","award":["2023B02036-1-2"],"award-info":[{"award-number":["2023B02036-1-2"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Early-weaned squabs are sensitive to dietary energy\u2013protein supply, but combined effects remain unclear. We tested metabolizable energy (ME; 11.9, 12.2, and 12.5 MJ\/kg) and crude protein (CP; 18, 19, and 20%) in 216 15-day-old gray-feathered King pigeon (Columba livia domestica) squabs using a 3 \u00d7 3 factorial design. Higher ME increased abdominal fat percentage, whereas CP affected slaughter traits. ME \u00d7 CP interactions occurred for live weight, liver index, breast and leg muscle quality, and most digestive enzyme activities. At 18% CP, live weight was significantly higher at 12.5 than at 12.2 MJ\/kg ME, whereas the opposite numerical trend occurred at 19% CP. Liver index was lower at 18% CP + 11.9 MJ\/kg ME than at 18% CP + 12.2 MJ\/kg ME. At 12.5 MJ\/kg ME, breast muscle a* was lower at 20% CP than at 18% or 19% CP. Enzyme activities were generally highest at 20% CP + 11.9 MJ\/kg ME. Targeted 16S rRNA sequencing associated the highest-energy\/lowest-protein treatment with Lactobacillus-related taxa, whereas the opposite treatment showed higher diversity and greater contributions of Pseudomonadota- and Enterobacterales-related taxa. Responses were trait-specific; microbial findings represent associations between two contrasting diets.<\/jats:p>","DOI":"10.3390\/life16081273","type":"journal-article","created":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T15:02:01Z","timestamp":1785510121000},"page":"1273","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Dietary Energy\u2013Protein Balance Regulates Slaughter Traits, Meat Quality, Digestive Enzyme Activity, and Fecal Microbiota in Early-Weaned Gray-Feathered King Pigeon Squabs"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-2740-5372","authenticated-orcid":false,"given":"Yuanhao","family":"Li","sequence":"first","affiliation":[{"name":"College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaobin","family":"Li","sequence":"additional","affiliation":[{"name":"College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huiguo","family":"Yang","sequence":"additional","affiliation":[{"name":"Xinjiang Academy of Animal Husbandry Sciences, Urumqi 830011, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Haiying","family":"Li","sequence":"additional","affiliation":[{"name":"College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yafei","family":"Liang","sequence":"additional","affiliation":[{"name":"College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mingcong","family":"Ding","sequence":"additional","affiliation":[{"name":"College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Aikemu","family":"Maimaitijiang","sequence":"additional","affiliation":[{"name":"Moyu County Lanhai Pigeon Industry Development Co., Ltd., Hotan 848100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jie","family":"Ren","sequence":"additional","affiliation":[{"name":"College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Honglei","family":"Sun","sequence":"additional","affiliation":[{"name":"College of Animal Science, Xinjiang Agricultural University, Urumqi 830052, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiajia","family":"Liu","sequence":"additional","affiliation":[{"name":"Xinjiang Academy of Animal Husbandry Sciences, Urumqi 830011, China"},{"name":"Moyu County Lanhai Pigeon Industry Development Co., Ltd., Hotan 848100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Xu, X., Wang, Z., Jian, Y., Zhang, L., Zhou, C., Liu, L., and Liu, H. (2025). Establishment and maturation of gut microbiota in White King pigeon squabs: Role of pigeon milk. Front. Microbiol., 15.","DOI":"10.3389\/fmicb.2024.1481529"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1080\/00439339.2020.1865117","article-title":"Optimisation of dietary energy utilisation for poultry\u2014A literature review","volume":"77","author":"Musigwa","year":"2021","journal-title":"World\u2019s Poult. Sci. J."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"102353","DOI":"10.1016\/j.psj.2022.102353","article-title":"Dietary metabolizable energy and crude protein levels affect pectoral muscle composition and gut microbiota in native growing chickens","volume":"102","author":"Chang","year":"2023","journal-title":"Poult. Sci."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Wang, D., Zhou, L., Shi, L., Cao, T., Abouelezz, K., and Hou, G. (2025). Dietary apparent metabolizable energy and crude protein levels influence slaughter performance, meat quality, and amino acid composition in slow-growing Danzhou chicken meat. Front. Anim. Sci., 6.","DOI":"10.3389\/fanim.2025.1646519"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1079\/WPS20020013","article-title":"Poultry meat quality","volume":"58","author":"Fletcher","year":"2002","journal-title":"World\u2019s Poult. Sci. J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"103577","DOI":"10.1016\/j.psj.2024.103577","article-title":"Measuring water holding capacity in poultry meat","volume":"103","author":"Barbut","year":"2024","journal-title":"Poult. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1016\/j.anifeedsci.2018.10.008","article-title":"The effect of microbiome modulation on the intestinal health of poultry","volume":"250","author":"Kogut","year":"2019","journal-title":"Anim. Feed. Sci. Technol."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"105313","DOI":"10.1016\/j.isci.2022.105313","article-title":"Dietary protein and the intestinal microbiota: An understudied relationship","volume":"25","author":"Bartlett","year":"2022","journal-title":"iScience"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"102577","DOI":"10.1016\/j.psj.2023.102577","article-title":"Effect of different dietary energy\/protein ratios on growth performance, reproductive performance of breeding pigeons and slaughter performance, meat quality of squabs in summer","volume":"102","author":"Peng","year":"2023","journal-title":"Poult. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"102964","DOI":"10.1016\/j.psj.2023.102964","article-title":"Optimal dietary energy and protein levels for breeding pigeons in the winter 2 + 3 lactation pattern","volume":"102","author":"Peng","year":"2023","journal-title":"Poult. Sci."},{"key":"ref_11","unstructured":"China Feed Database (2024). Tables of Feed Composition and Nutritive Values in China, China Feed. [35th ed.]. (In Chinese)."},{"key":"ref_12","unstructured":"Ministry of Agriculture and Rural Affairs of the People\u2019s Republic of China (2020). Performance Terminology and Measurement Calculation Methods of Poultry Production, (In Chinese)."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"100331","DOI":"10.1016\/j.animal.2021.100331","article-title":"Review: Production factors affecting poultry carcass and meat quality attributes","volume":"16","author":"Guillier","year":"2022","journal-title":"Animal"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1057","DOI":"10.5713\/ajas.2013.13702","article-title":"Nutritional factors affecting abdominal fat deposition in poultry: A review","volume":"27","author":"Fouad","year":"2014","journal-title":"Asian-Australas. J. Anim. Sci."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"102224","DOI":"10.1016\/j.psj.2022.102224","article-title":"Effects of feed systems on growth performance, carcass characteristics, organ index, and serum biochemical parameters of pigeon","volume":"101","author":"Zhang","year":"2022","journal-title":"Poult. Sci."},{"key":"ref_16","first-page":"1","article-title":"Effects of dietary crude protein levels on growth performance, carcass characteristics, meat quality of squabs and laying performance of breeding pigeons","volume":"37","author":"Gao","year":"2016","journal-title":"J. S. China Agric. Univ."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Kokoszynski, D., Steczny, K., Zochowska-Kujawska, J., Sobczak, M., Kotowicz, M., Saleh, M., Fik, M., Arpasova, H., Hrncar, C., and Wlodarczyk, K. (2020). Carcass characteristics, physicochemical properties, and texture and microstructure of the meat and internal organs of carrier and king pigeons. Animals, 10.","DOI":"10.3390\/ani10081315"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1181","DOI":"10.5713\/ab.20.0755","article-title":"Effects of dietary hatchery by-products on growth performance, relative organ weight, plasma measurements, immune organ index, meat quality, and tibia characteristics of broiler chickens","volume":"34","author":"Choi","year":"2021","journal-title":"Anim. Biosci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"867","DOI":"10.3382\/ps\/pev443","article-title":"Growth curves and age-related changes in carcass characteristics, organs, serum parameters, and intestinal transporter gene expression in domestic pigeon (Columba livia)","volume":"95","author":"Gao","year":"2016","journal-title":"Poult. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Wang, L., Zhu, J., Xie, P., and Gong, D. (2023). Pigeon during the breeding cycle: Behaviors, composition and formation of crop milk, and physiological adaptation. Life, 13.","DOI":"10.3390\/life13091866"},{"key":"ref_21","first-page":"873","article-title":"Poultry meat quality in relation to muscle growth and muscle fiber characteristics","volume":"37","author":"Ismail","year":"2017","journal-title":"Korean J. Food Sci. Anim. Resour."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2438","DOI":"10.3382\/ps.2013-03087","article-title":"Comparison of breast muscle traits and meat quality characteristics in 2 commercial chicken hybrids","volume":"92","author":"Petracci","year":"2013","journal-title":"Poult. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"2997","DOI":"10.1007\/s13197-017-2789-z","article-title":"Determinants of broiler chicken meat quality and factors affecting them: A review","volume":"54","author":"Mir","year":"2017","journal-title":"J. Food Sci. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"105000","DOI":"10.1016\/j.psj.2025.105000","article-title":"Influencing factors and quality traits of pigeon meat: A systematic review","volume":"104","author":"Lan","year":"2025","journal-title":"Poult. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Liu, T., Wang, L., Jiang, X., Liu, Y., Diao, E., and Xie, P. (2023). Free-choice feeding of whole grains improves meat quality and intestinal development of pigeon squabs compared with complete pelleted feed. Life, 13.","DOI":"10.3390\/life13030848"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2230","DOI":"10.1016\/j.psj.2019.10.076","article-title":"Physicochemical characteristics of breast and thigh meats from old broiler breeder hen and old laying hen and their effects on quality properties of pressed ham","volume":"99","author":"Choe","year":"2020","journal-title":"Poult. Sci."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Ravindran, V., and Abdollahi, M.R. (2021). Nutrition and digestive physiology of the broiler chick: State of the art and outlook. Animals, 11.","DOI":"10.3390\/ani11102795"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1886","DOI":"10.3382\/ps.2011-02091","article-title":"Posthatch development of intestinal morphology and digestive enzyme activities in domestic pigeons (Columba livia)","volume":"91","author":"Dong","year":"2012","journal-title":"Poult. Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"101613","DOI":"10.1016\/j.psj.2021.101613","article-title":"Effects of early weaning on intestinal morphology, digestive enzyme activity, antioxidant status, and cytokine status in domestic pigeon squabs (Columba livia)","volume":"101","author":"Wen","year":"2022","journal-title":"Poult. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Gillespie, M.J., Stanley, D., Chen, H., Donald, J.A., Nicholas, K.R., Moore, R.J., and Crowley, T.M. (2012). Functional similarities between pigeon milk and mammalian milk: Induction of immune gene expression and modification of the microbiota. PLoS ONE, 7.","DOI":"10.1371\/journal.pone.0048363"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"102681","DOI":"10.1016\/j.psj.2023.102681","article-title":"Chemical composition of pigeon crop milk and factors affecting its production: A review","volume":"102","author":"Jin","year":"2023","journal-title":"Poult. Sci."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1690","DOI":"10.1093\/ps\/86.8.1690","article-title":"Effects of dietary metabolizable energy and crude protein content on the activities of digestive enzymes in jejunal fluid of Peking ducks","volume":"86","author":"Zhao","year":"2007","journal-title":"Poult. Sci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1641","DOI":"10.3382\/ps.2011-02081","article-title":"Effects of dietary protein source on the digestive enzyme activities and electrolyte composition in the small intestinal fluid of chickens","volume":"91","author":"Ren","year":"2012","journal-title":"Poult. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"103852","DOI":"10.1016\/j.psj.2024.103852","article-title":"Intestinal health of squab pigeons responded to parental dietary protein levels during breeding period","volume":"103","author":"Cheng","year":"2024","journal-title":"Poult. Sci."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1006","DOI":"10.3382\/ps\/pex359","article-title":"The gastrointestinal microbiome and its association with the control of pathogens in broiler chicken production: A review","volume":"97","author":"Clavijo","year":"2018","journal-title":"Poult. Sci."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Rychlik, I. (2020). Composition and function of chicken gut microbiota. Animals, 10.","DOI":"10.3390\/ani10010103"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"2","DOI":"10.1186\/s40104-018-0310-9","article-title":"Strategies to modulate the intestinal microbiota and their effects on nutrient utilization, performance, and health of poultry","volume":"10","author":"Yadav","year":"2019","journal-title":"J. Anim. Sci. Biotechnol."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"410","DOI":"10.1038\/s41579-018-0029-9","article-title":"Best practices for analysing microbiomes","volume":"16","author":"Knight","year":"2018","journal-title":"Nat. Rev. Microbiol."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Xu, Q., Jian, H., Zhao, W., Li, J., Zou, X., and Dong, X. (2022). Early weaning stress induces intestinal microbiota disturbance, mucosal barrier dysfunction and inflammation response activation in pigeon squabs. Front. Microbiol., 13.","DOI":"10.3389\/fmicb.2022.877866"},{"key":"ref_40","first-page":"32","article-title":"A new method for non-parametric multivariate analysis of variance","volume":"26","author":"Anderson","year":"2001","journal-title":"Austral Ecol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"R60","DOI":"10.1186\/gb-2011-12-6-r60","article-title":"Metagenomic biomarker discovery and explanation","volume":"12","author":"Segata","year":"2011","journal-title":"Genome Biol."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Ding, J., Liao, N., Zheng, Y., Yang, L., Zhou, H., Xu, K., Han, C., Luo, H., Qin, C., and Tang, C. (2020). The composition and function of pigeon milk microbiota transmitted from parent pigeons to squabs. Front. Microbiol., 11.","DOI":"10.3389\/fmicb.2020.01789"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"3963","DOI":"10.3382\/ps\/pez132","article-title":"Effect of a low protein diet on chicken ceca microbiome and productive performances","volume":"98","author":"Sala","year":"2019","journal-title":"Poult. Sci."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1016\/j.tibtech.2015.06.011","article-title":"Proteobacteria: Microbial signature of dysbiosis in gut microbiota","volume":"33","author":"Shin","year":"2015","journal-title":"Trends Biotechnol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"18","DOI":"10.1038\/mi.2016.75","article-title":"Mechanisms of inflammation-driven bacterial dysbiosis in the gut","volume":"10","author":"Zeng","year":"2017","journal-title":"Mucosal Immunol."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1016\/j.cell.2009.09.033","article-title":"Induction of intestinal Th17 cells by segmented filamentous bacteria","volume":"139","author":"Ivanov","year":"2009","journal-title":"Cell"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1017\/S0043933915000124","article-title":"Dietary factors affecting hindgut protein fermentation in broilers: A review","volume":"71","author":"Qaisrani","year":"2015","journal-title":"World\u2019s Poult. Sci. J."},{"key":"ref_48","doi-asserted-by":"crossref","unstructured":"Wu, S., Bhat, Z.F., Gounder, R.S., Mohamed Ahmed, I.A., Al-Juhaimi, F.Y., Ding, Y., and Bekhit, A.E.D.A. (2022). Effect of dietary protein and processing on gut microbiota\u2014A systematic review. Nutrients, 14.","DOI":"10.3390\/nu14030453"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"G159","DOI":"10.1152\/ajpgi.00319.2017","article-title":"Protein fermentation in the gut; implications for intestinal dysfunction in humans, pigs, and poultry","volume":"315","author":"Gilbert","year":"2018","journal-title":"Am. J. Physiol.-Gastrointest. Liver Physiol."}],"container-title":["Life"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-1729\/16\/8\/1273\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,31]],"date-time":"2026-07-31T15:07:55Z","timestamp":1785510475000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-1729\/16\/8\/1273"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,31]]},"references-count":49,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["life16081273"],"URL":"https:\/\/doi.org\/10.3390\/life16081273","relation":{},"ISSN":["2075-1729"],"issn-type":[{"value":"2075-1729","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,31]]}}}