{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T16:33:01Z","timestamp":1773678781947,"version":"3.50.1"},"reference-count":39,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T00:00:00Z","timestamp":1773619200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Key Science and Technology Program of Inner Mongolia Autonomous Region","award":["zdzx2018001"],"award-info":[{"award-number":["zdzx2018001"]}]},{"name":"High-level Talent Start-up Research Project of Inner Mongolia Agricultural University","award":["NDYB2020-4"],"award-info":[{"award-number":["NDYB2020-4"]}]},{"name":"Basic Research Fund for Universities in Inner Mongolia Autonomous Region","award":["BR251030"],"award-info":[{"award-number":["BR251030"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>This study evaluated the effects of dietary protein levels during late gestation on nutrient digestibility, plasma amino acid profiles in jennies, and donkey foal growth performance. Twenty-four pregnant jennies were randomly assigned to one of three diets with different crude protein (CP) contents during late gestation: 12.48% (HP), 11.52% (MP), and 10.54% (LP) on a dry matter basis. All animals received the same diet immediately after parturition for a duration of 30 days. During the trial, two digestion experiments were conducted, blood samples were collected at 28 and 7 days prepartum, and weekly weight measurements of jennies and foals were recorded. The results indicated that the dietary protein level did not significantly affect feed intake in late gestation. However, apparent nutrient digestibility of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and ether extract (EE), and calcium (Ca) and phosphorus (P) was generally higher in the MP and LP groups than in the HP group, with MP showing the most consistent improvements across nutrients and timepoints (p &lt; 0.05). Although the HP diet increased plasma concentrations of certain amino acids, including glutamic acid (Glu), valine (Val), methionine (Met), leucine (Leu), essential amino acids (EAAs), functional amino acids (FAAs), and branched chain amino acids (BCAAs), and elevated serum levels of glucose (GLU), blood urea nitrogen (BUN), and creatinine (CRE), it failed to improve postpartum weight recovery in jennies, highlighting that weight dynamics during this period are governed by factors beyond dietary protein content alone. Specifically, the LP group exhibited significantly higher cumulative postpartum weight loss over weeks 1\u20134 than the HP group (p = 0.004). Regarding offspring performance, both HP and MP diets improved foal birth weight, weekly body weight up to 4 weeks, average daily gain, and body height compared to the LP group (p &lt; 0.05), with no significant differences observed between the HP and MP groups. In conclusion, for jennies under the current confined feeding system, a late-gestation diet containing 11.52% CP was adequate to support higher nutrient digestibility in the jennies and better growth performance in their foals, compared to a lower protein level (10.54% CP). However, increasing the dietary CP to 12.48% provided no additional benefits in nutrient utilization or overall productivity.<\/jats:p>","DOI":"10.3390\/ani16060929","type":"journal-article","created":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T15:21:16Z","timestamp":1773674476000},"page":"929","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Dietary Protein Level in Late Gestation: Effects on Nutritional and Developmental Responses in Jennies and Their Foals"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5533-9496","authenticated-orcid":false,"given":"Yongmei","family":"Guo","sequence":"first","affiliation":[{"name":"Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, Inner Mongolia Agricultural University, Hohhot 010018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiarong","family":"Li","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, Inner Mongolia Agricultural University, Hohhot 010018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yajun","family":"Shen","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, Inner Mongolia Agricultural University, Hohhot 010018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4107-2858","authenticated-orcid":false,"given":"Sumei","family":"Yan","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, Inner Mongolia Agricultural University, Hohhot 010018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8550-3509","authenticated-orcid":false,"given":"Binlin","family":"Shi","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, Inner Mongolia Agricultural University, Hohhot 010018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanli","family":"Zhao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, Inner Mongolia Agricultural University, Hohhot 010018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaoyu","family":"Guo","sequence":"additional","affiliation":[{"name":"Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, Inner Mongolia Agricultural University, Hohhot 010018, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,16]]},"reference":[{"key":"ref_1","first-page":"3","article-title":"Advances in pharmacological and pharmacodynamic research of Colla Corii Asini","volume":"17","author":"Ina","year":"2017","journal-title":"World Abstr. Latest Med. Inf."},{"key":"ref_2","first-page":"374","article-title":"Study on the Active Components of Donkey-Hide Gelatin and Its Anti-Fatigue Effects in Exercising Mice","volume":"32","author":"Li","year":"2011","journal-title":"Food Ind. Technol."},{"key":"ref_3","first-page":"11","article-title":"The meat utility of donkeys and the nutritional value of donkey meat","volume":"33","author":"Li","year":"2018","journal-title":"Livest. Ind. Xinjiang"},{"key":"ref_4","first-page":"4574","article-title":"Chemical nutrient composition of donkey milk and its biological activity (in English)","volume":"8","author":"Zhang","year":"2017","journal-title":"J. Food Saf. Qual. Test."},{"key":"ref_5","first-page":"2815","article-title":"Effects of Dietary Protein Level of Female Donkeys during Late Gestation on Protein, Fat and Amino Acid Contents in Colostrum and Regular Milk","volume":"33","author":"Liang","year":"2021","journal-title":"Chin. J. Anim. Nutr."},{"key":"ref_6","unstructured":"Li, Z. (2019). Effects of Dietary Protein Levels on Milk Production Performance and Nutrient Digestibility in Lactating Donkeys. [Master\u2019s Thesis, Inner Mongolia Agricultural University]."},{"key":"ref_7","unstructured":"Yin, G. (2022). Effects of Late Gestation Dietary Energy Levels on Nutrient Digestibility and Metabolism in Sows, Postpartum Milk Yield, and Foal Growth and Development. [Master\u2019s Thesis, Inner Mongolia Agricultural University]."},{"key":"ref_8","unstructured":"Yan, Z. (2020). Study on the Effects of Dietary Energy Levels on Growth and Fattening Performance, Slaughter Characteristics, and Meat Quality in Meat Donkeys, and the Underlying Mechanisms. [Master\u2019s Thesis, Inner Mongolia Agricultural University]."},{"key":"ref_9","first-page":"3593","article-title":"Effects of Dietary Protein Levels on Weight Gain and Lambing Rate in Pregnant Hainan Black Goats","volume":"52","author":"Wu","year":"2013","journal-title":"Hubei Agric. Sci."},{"key":"ref_10","first-page":"18","article-title":"Effects of Different Protein Levels in Daily Rations on Reproductive Performance, Serum Parameters and Amino Acid Concentrations in Colostrum of Late-Pregnancy Sows","volume":"42","author":"Yu","year":"2020","journal-title":"Fujian Anim. Husb. Vet. Med."},{"key":"ref_11","first-page":"26","article-title":"Effects of Dietary Energy and Protein Levels on Growth and Reproduction in Young Female Yanshan Angora Goats","volume":"41","author":"Li","year":"2020","journal-title":"J. Domest. Anim. Ecol."},{"key":"ref_12","unstructured":"(2003). Determination of Amino Acids in Foods (Standard No. GB\/T 5009.124-2003)."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Wang, Y., Diao, K., Li, H., Zhang, C., Zhang, G., and Guo, C. (2025). Effects of Dietary Protein Levels on Production Performance, Meat Quality Traits, and Gut Microbiome of Fatting Dezhou Donkeys. Microorganisms, 13.","DOI":"10.3390\/microorganisms13061388"},{"key":"ref_14","first-page":"22","article-title":"Effects of Diets with Different Protein Levels on Dairy Cow Production Performance in the Peripartum Period","volume":"11","author":"Yin","year":"2008","journal-title":"Heilongjiang Anim. Husb. Vet. Med."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8928","DOI":"10.3168\/jds.2017-12718","article-title":"Effect of substituting soybean meal and canola cake with dried distillers grains with solubles at 2 dietary crude protein levels on feed intake, milk production, and milk quality in dairy cows","volume":"100","author":"Gaillard","year":"2017","journal-title":"J. Dairy Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"251","DOI":"10.21474\/IJAR01\/19250","article-title":"Effect of Dietary Crude Protein on Ammonia Emission, Blood Profile and Production Performance of Broiler Chickens","volume":"12","author":"Hossain","year":"2024","journal-title":"Int. J. Adv. Res."},{"key":"ref_17","first-page":"40","article-title":"Effects of Concentrate Mixtures with Different Protein Levels on the Growth Performance of Foals","volume":"36","author":"Hui","year":"2015","journal-title":"J. Domest. Anim. Ecol."},{"key":"ref_18","first-page":"272","article-title":"Effects of Different Nutritional Levels in Feed on Body Weight, Digestive Metabolism in Late Pregnancy, and Colostrum Composition Post-Partum in Ili Horses","volume":"48","author":"Wang","year":"2017","journal-title":"J. Vet. Med."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"299","DOI":"10.17221\/72\/2023-VETMED","article-title":"The use of functional amino acids in different categories of pigs\u2014A review","volume":"68","author":"Hodkovicova","year":"2023","journal-title":"Vet. Med."},{"key":"ref_20","first-page":"2656","article-title":"Effects of Energy, Protein and Amino Acid Levels in Late Gestation Diets on Mammary Gland Development and Piglet Growth","volume":"44","author":"Zhang","year":"2017","journal-title":"Chin. J. Anim. Husb. Vet. Med."},{"key":"ref_21","first-page":"2392","article-title":"Dynamic Changes in Plasma Free Amino Acid Metabolism Profiles in Muscovy Ducks Aged 1\u201370 Days","volume":"37","author":"Zhang","year":"2025","journal-title":"J. Anim. Nutr."},{"key":"ref_22","first-page":"35","article-title":"Effects of Different Amino Acid Levels on Reproductive Performance, Umbilical Cord Characteristics, Lactation Performance in Sows, and Growth Performance in Offspring Piglets","volume":"60","author":"Cong","year":"2025","journal-title":"J. Gansu Agric. Univ."},{"key":"ref_23","first-page":"31","article-title":"Effects of Diets with Different Protein Levels on Farrowing Performance, Serum Biochemical Parameters and Nitrogen Excretion in Late-Pregnancy Sows","volume":"52","author":"Yu","year":"2020","journal-title":"Anim. Husb. Vet. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2832","DOI":"10.1002\/jsfa.13171","article-title":"Maternal folic acid and vitamin B(12) supplementation during medium to late gestation promotes fetal development via improving placental antioxidant capacity, angiogenesis and amino acid transport","volume":"104","author":"Zhou","year":"2024","journal-title":"J. Sci. Food Agric."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1007\/s00726-014-1861-5","article-title":"Glutamate-glutamine cycle and exchange in the placenta-fetus unit during late pregnancy","volume":"47","author":"Wu","year":"2015","journal-title":"Amino Acids"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1111\/j.2042-3306.1987.tb01374.x","article-title":"Synthesis and absorption of cysteine from the hindgut of the horse","volume":"19","author":"McMeniman","year":"1987","journal-title":"Equine Vet. J."},{"key":"ref_27","first-page":"75","article-title":"The Effect of Dietary Protein Levels in Lactating Donkeys on Foal Growth and Development","volume":"44","author":"Chi","year":"2021","journal-title":"Feed Res."},{"key":"ref_28","first-page":"6601","article-title":"Effects of Dietary Net Energy Levels on Growth Performance, Apparent Nutrient Digestibility, and Blood Biochemical Parameters in Guangdong Small-Eared Piglets (4.5\u201313.0 kg)","volume":"37","author":"Wen","year":"2025","journal-title":"J. Anim. Nutr."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"skac176","DOI":"10.1093\/jas\/skac176","article-title":"Review: Physiology and nutrition of late gestating and transition sows","volume":"100","author":"Theil","year":"2022","journal-title":"J. Anim. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"skab040","DOI":"10.1093\/jas\/skab040","article-title":"Optimal feed level during the transition period to achieve faster farrowing and high colostrum yield in sows","volume":"99","author":"Feyera","year":"2021","journal-title":"J. Anim. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"206","DOI":"10.1093\/jn\/118.2.206","article-title":"Responses of blood glucose, insulin and cortisol concentrations to common equine diets","volume":"118","author":"Stull","year":"1988","journal-title":"J. Nutr."},{"key":"ref_32","first-page":"41","article-title":"Study on the Effects of Dietary Crude Protein Levels and Premixes on Body Weight, Blood Biochemical Parameters, and Hormone Levels in Pre-breeding Female Donkeys","volume":"55","author":"Jing","year":"2023","journal-title":"Anim. Husb. Vet. Sci."},{"key":"ref_33","first-page":"39","article-title":"Effects of Replacing Soybean Meal with Low-Double-Low Rapeseed Meal in Low-Protein Diets on Growth Performance and Serum Biochemical Parameters in Finishing Pigs","volume":"46","author":"Wei","year":"2025","journal-title":"Feed Ind."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"304","DOI":"10.1016\/j.aninu.2025.06.010","article-title":"Increased maternal valine intake in low-protein diets accelerates growth performance of suckling piglets by improving mammary gland-fetal intestinal metabolism","volume":"23","author":"Wei","year":"2025","journal-title":"Anim. Nutr."},{"key":"ref_35","unstructured":"Zhiwei, Z. (2020). Effects of Gestational Nutritional Status on Body Condition in Primiparous Sows and on Muscle Fibre Characteristics and Gene Expression Levels Related to Muscle Development in Offspring. [Master\u2019s Thesis, Heilongjiang Bayi Agricultural University]."},{"key":"ref_36","first-page":"2707","article-title":"Effects of Grazing with Supplementary Ration and Concentrate Feeding on Body Weight, Serum Biochemical Parameters, and Mineral Content in Late-Pregnancy and Pre-Lactation Sunite Ewes","volume":"33","author":"Zhao","year":"2021","journal-title":"J. Anim. Nutr."},{"key":"ref_37","first-page":"43","article-title":"Protein-Requirements-and-Digestibility: A Review","volume":"1","author":"Pagan","year":"1998","journal-title":"Adv. Equine Nutr."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1227","DOI":"10.2527\/1995.7351227x","article-title":"Production by ewes rearing single or twin lambs: Effects of dietary crude protein percentage and supplemental zinc methionine","volume":"73","author":"Hatfield","year":"1995","journal-title":"J. Anim. Sci."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"422","DOI":"10.1016\/S0737-0806(06)80136-X","article-title":"Benefits to foals of feeding soybean meal to lactating broodmares","volume":"10","author":"Glade","year":"1990","journal-title":"Equine Vet. Sci."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/6\/929\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T15:24:05Z","timestamp":1773674645000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/16\/6\/929"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,16]]},"references-count":39,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["ani16060929"],"URL":"https:\/\/doi.org\/10.3390\/ani16060929","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,16]]}}}