{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,5]],"date-time":"2026-01-05T06:39:20Z","timestamp":1767595160169,"version":"3.48.0"},"reference-count":50,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,1,5]],"date-time":"2026-01-05T00:00:00Z","timestamp":1767571200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Vet. Sci."],"abstract":"<jats:p>\n                    This study aimed to evaluate the effect of humic acid (HA) on growth performance, nutrient digestibility, ruminal fermentation, ruminal enzyme activity, and certain blood biochemical parameters. A total of 45 calves (11\u202f\u00b1\u202f0.25\u202fmonths of age; 280\u202f\u00b1\u202f5.55\u202fkg BW) were divided equally into three groups. The control group received a basal diet composed of a concentrate feed mixture (CFM) with roughage. The treatment groups received the same basal diet supplemented with 1 and 2% humic acid in the CFM, respectively. The study revealed that the treatment groups had significantly lower total dry matter (DM) intake (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.029). The treatment groups showed higher (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.013) ether extract (EE) digestibility and digestible crude protein (DCP) (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.001) than the CFM group. However, ammonia nitrogen (NH\n                    <jats:sub>3<\/jats:sub>\n                    -N, mg\/100\u202fmL) was significantly lower (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.012) in the 1% HA and 2% HA groups compared to the CFM group. The 2% HA group had significantly higher (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.001) proportions of acetate and propionate compared to the 1% HA and CFM groups. The treatment groups had significantly higher (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.001)\n                    <jats:italic>\u03b1<\/jats:italic>\n                    -amylase, lipase, urease, and protease activities compared to the CFM group. In addition, the concentration of total soluble protein in the rumen liquid was higher (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.006) in the 1% HA group compared to the CFM group. The 2% HA group had higher (\n                    <jats:italic>p<\/jats:italic>\n                    \u202f=\u202f0.049) glucose concentrations than the CFM group. In conclusion, humic acid supplementation at 1% or 2% may improve nutrient digestibility and ruminal fermentation efficiency, enhance enzyme activity, and support normal blood profiles in calves.\n                  <\/jats:p>","DOI":"10.3389\/fvets.2025.1704848","type":"journal-article","created":{"date-parts":[[2026,1,5]],"date-time":"2026-01-05T06:36:16Z","timestamp":1767594976000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Digestibility, ruminal enzyme activity, fermentation characteristics, and selected blood biochemical parameters in calves supplemented with humic acid"],"prefix":"10.3389","volume":"12","author":[{"given":"Waleed K.","family":"Abouamra","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abdelslam M. A.","family":"Amhabj","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hamdan M.","family":"Tawfik","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ahmed A.","family":"Ayad","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohsen M.","family":"Farghaly","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hayam M. A.","family":"Monzaly","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mohsen A.","family":"Khormi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ramadan","family":"Taha","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ahmed Ezzat","family":"Ahmed","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Amira K.","family":"Hajri","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marzough Aziz","family":"Albalawi","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Montaser 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species isolated from retail raw milk","volume":"16","author":"Osman","year":"2016","journal-title":"BMC Microbiol"},{"key":"ref4","doi-asserted-by":"publisher","first-page":"17","DOI":"10.1016\/j.ijvsm.2016.10.003","article-title":"Clinical, hemato-biochemical alterations and oxidant\u2013antioxidant biomarkers in Babesia-infected calves","volume":"4","author":"Salem","year":"2016","journal-title":"Int J Vet Sci Med"},{"key":"ref5","doi-asserted-by":"publisher","first-page":"148491","DOI":"10.1016\/j.gene.2024.148491","article-title":"First characterization of major histocompatibility complex class II DRB3 diversity in cattle breeds raised in Egypt","volume":"918","author":"Hamada","year":"2024","journal-title":"Gene"},{"key":"ref6","doi-asserted-by":"publisher","first-page":"89","DOI":"10.1016\/j.vetmic.2017.07.018","article-title":"Molecular characterization of circulating foot and mouth disease virus (FMDV) serotype O topotype EA-3 and serotype a (African topotype) genotype IV in 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reaction for determination of ammonia","volume":"39","author":"Weatherburn","year":"1967","journal-title":"Anal Chem"},{"key":"ref33","doi-asserted-by":"publisher","first-page":"32","DOI":"10.1099\/00221287-92-1-32","article-title":"Urease activity in the rumen of sheep and the isolation of ureolytic bacteria","volume":"92","author":"Cook","year":"1976","journal-title":"Microbiology"},{"key":"ref34","doi-asserted-by":"publisher","first-page":"624","DOI":"10.1093\/clinchem\/11.6.624","article-title":"Automated and manual direct methods for the determination of blood urea","volume":"11","author":"Marsh","year":"1965","journal-title":"Clin Chem"},{"key":"ref35","doi-asserted-by":"publisher","first-page":"265","DOI":"10.1016\/S0021-9258(19)52451-6","article-title":"Protein measurement with the Folin phenol reagent","volume":"193","author":"Lowry","year":"1951","journal-title":"J Biol Chem"},{"key":"ref36","doi-asserted-by":"publisher","first-page":"1096","DOI":"10.1093\/clinchem\/44.5.1096","article-title":"Standards of laboratory practice: cardiac drug monitoring","volume":"44","author":"Valdes","year":"1998","journal-title":"Clin Chem"},{"key":"ref37","doi-asserted-by":"publisher","first-page":"579","DOI":"10.1177\/000456329703400601","article-title":"Effects of drugs on clinical laboratory tests","volume":"34","author":"Young","year":"1997","journal-title":"Ann Clin Biochem"},{"key":"ref38","doi-asserted-by":"publisher","first-page":"2914","DOI":"10.3390\/ani14192914","article-title":"Thyme and oregano oil potential therapeutics against malathion toxicity through biochemical, histological, and cytochrome P450 1A2 activities in male Wistar rats","volume":"14","author":"Al-Saeed","year":"2024","journal-title":"Animals"},{"key":"ref39","volume-title":"Principles and procedures of statistics, a biometrical approach","author":"Steel","year":"1981"},{"key":"ref40","doi-asserted-by":"publisher","first-page":"126","DOI":"10.3923\/pjn.2005.126.134","article-title":"Humic acid substances in animal agriculture","volume":"4","author":"Islam","year":"2005","journal-title":"Pak J Nutr"},{"key":"ref41","doi-asserted-by":"publisher","first-page":"475","DOI":"10.3390\/vetsci9090475","article-title":"Essential oils as a dietary additive for small ruminants: a meta-analysis on performance, rumen parameters, serum metabolites, and product quality","volume":"9","author":"Dorantes-Iturbide","year":"2022","journal-title":"Vet Sci"},{"key":"ref42","doi-asserted-by":"publisher","first-page":"105","DOI":"10.22358\/jafs\/92074\/2018","article-title":"Impact of humic acid as an organic additive on ruminal fermentation constituents, blood parameters and milk production in goats and their kids growth rate","volume":"27","author":"El-Zaiat","year":"2018","journal-title":"J Anim Feed 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Department of Animal and Life Science","volume":"188","author":"Galyean","year":"1986","journal-title":"New Mexico State University, USA,"},{"key":"ref50","volume-title":"Association of Official Analytical Chemists, 16th ed. 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