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Wu F, Ji P, Yang H, Zhu X, Wu X. Interpretation of the effects of rumen acidosis on the gut microbiota and serum metabolites in calves based on 16S rDNA sequencing and non-target metabolomics. Front Cell Infect Microbiol 2024; 14:1427763. [PMID: 39006744 PMCID: PMC11239342 DOI: 10.3389/fcimb.2024.1427763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Accepted: 06/12/2024] [Indexed: 07/16/2024] Open
Abstract
Introduction Rumen acidosis is one of the most common diseases in beef cattle. It severely affects the normal development of calves and poses a significant threat to the farming industry. However, the influence of rumen acidosis on the gut microbiota and serum metabolites of calves is currently unclear. Objective The aim of this study is to investigate the changes in the gut microbiota and serum metabolites in calves after rumen acidosis and analyse the correlation. Methods Eight calves were selected as the rumen acidosis group, and eight health calves were selected as the healthy group. The faecal gut microbiota and serum metabolites of calves were detected respectively using 16S rDNA high-throughput sequencing and non-target metabolomics. The correlation between gut microbiota and serum metabolites was analyzed by Spearman correlation analysis. Results Differential analysis of the diversity and composition of gut microbiota between eight male healthy (Health) and eight male rumen acidosis (Disease) calves revealed that rumen acidosis increased the abundance of the gut microbiota in calves. At the phylum level, compared to the Healthy group, the relative abundance of Proteobacteria in the Disease group significantly decreased (P<0.05), while the relative abundance of Desulfobacterota significantly increased in the Disease group (P<0.05). At the genus level, compared to the Disease group, the relative abundance of Alloprevotella, Muribaculaceae, Succinivibrio, Prevotella, Agathobacter and Parabacteroides significantly increased in the Healthy group (P<0.05), while the relative abundance of Christensenellaceae_R-7 and Monoglobus significantly decreased in the Healthy group (P<0.05). Differential analysis results showed the Healthy group had 23 genera with higher abundance, while the Disease group had 47 genera with higher abundance. Serum metabolomics results revealed the differential metabolites associated with rumen acidosis, including nicotinamide, niacin, L-glutamic acid and carnosine, were mainly enriched in the nicotinate and nicotinamide pathway and the histidine pathway. Conclusion The occurrence of rumen acidosis can induce changes in the gut microbiota of calves, with a significant increase of the Christensenellaceae_R-7 genus and a significant decrease of Prevotella and Succinivibrio genera. In addition, the occurrence of rumen acidosis can also induce changes in serum metabolites including niacin, niacinamide, L-glutamine, and carnosine, which may serve as the diagnostic biomarkers of rumen acidosis of calves.
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Affiliation(s)
- Fanlin Wu
- Key Laboratory of Veterinary Pharmaceutical Development, Ministry of Agricultural and Rural Affairs, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Peng Ji
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Haochi Yang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Xiaopeng Zhu
- Zhangye Wanhe Grass Livestock Industry Science and Technology Development Co., Ltd, Zhangye, China
| | - Xiaohu Wu
- Key Laboratory of Veterinary Pharmaceutical Development, Ministry of Agricultural and Rural Affairs, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of Chinese Academy of Agricultural Sciences, Lanzhou, China
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Wu G, Bazer FW, Johnson GA, Satterfield MC, Washburn SE. Metabolism and Nutrition of L-Glutamate and L-Glutamine in Ruminants. Animals (Basel) 2024; 14:1788. [PMID: 38929408 PMCID: PMC11201166 DOI: 10.3390/ani14121788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 06/02/2024] [Accepted: 06/05/2024] [Indexed: 06/28/2024] Open
Abstract
Although both L-glutamate (Glu) and L-glutamine (Gln) have long been considered nutritionally nonessential in ruminants, these two amino acids have enormous nutritional and physiological importance. Results of recent studies revealed that extracellular Gln is extensively degraded by ruminal microbes, but extracellular Glu undergoes little catabolism by these cells due to the near absence of its uptake. Ruminal bacteria hydrolyze Gln to Glu plus ammonia and, intracellularly, use both amino acids for protein synthesis. Microbial proteins and dietary Glu enter the small intestine in ruminants. Both Glu and Gln are the major metabolic fuels and building blocks of proteins, as well as substrates for the syntheses of glutathione and amino acids (alanine, ornithine, citrulline, arginine, proline, and aspartate) in the intestinal mucosa. In addition, Gln and aspartate are essential for purine and pyrimidine syntheses, whereas arginine and proline are necessary for the production of nitric oxide (a major vasodilator) and collagen (the most abundant protein in the body), respectively. Under normal feeding conditions, all diet- and rumen-derived Glu and Gln are extensively utilized by the small intestine and do not enter the portal circulation. Thus, de novo synthesis (e.g., from branched-chain amino acids and α-ketoglutarate) plays a crucial role in the homeostasis of Glu and Gln in the whole body but may be insufficient for maximal growth performance, production (e.g., lactation and pregnancy), and optimal health (particularly intestinal health) in ruminants. This applies to all types of feeding systems used around the world (e.g., rearing on a milk replacer before weaning, pasture-based production, and total mixed rations). Dietary supplementation with the appropriate doses of Glu or Gln [e.g., 0.5 or 1 g/kg body weight (BW)/day, respectively] can safely improve the digestive, endocrine, and reproduction functions of ruminants to enhance their productivity. Both Glu and Gln are truly functional amino acids in the nutrition of ruminants and hold great promise for improving their health and productivity.
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Affiliation(s)
- Guoyao Wu
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA; (F.W.B.); (M.C.S.)
| | - Fuller W. Bazer
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA; (F.W.B.); (M.C.S.)
| | - Gregory A. Johnson
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA;
| | - M. Carey Satterfield
- Department of Animal Science, Texas A&M University, College Station, TX 77843, USA; (F.W.B.); (M.C.S.)
| | - Shannon E. Washburn
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843, USA;
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Silva FG, Silva SR, Pereira AMF, Cerqueira JL, Conceição C. A Comprehensive Review of Bovine Colostrum Components and Selected Aspects Regarding Their Impact on Neonatal Calf Physiology. Animals (Basel) 2024; 14:1130. [PMID: 38612369 PMCID: PMC11010951 DOI: 10.3390/ani14071130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 04/14/2024] Open
Abstract
Colostrum contains macro- and micronutrients necessary to meet the nutritional and energy requirements of the neonatal calf, bioactive components that intervene in several physiological aspects, and cells and microorganisms that modulate the calf's immune system and gut microbiome. Colostrum is sometimes mistaken as transition milk, which, although more nutritive than whole milk, has a distinct biochemical composition. Furthermore, most research about colostrum quality and colostrum management focuses on the transfer of maternal IgG to the newborn calf. The remaining components of colostrum and transition milk have not received the same attention, despite their importance to the newborn animal. In this narrative review, a large body of literature on the components of bovine colostrum was reviewed. The variability of these components was summarized, emphasizing specific components that warrant deeper exploration. In addition, the effects of each component present in colostrum and transition milk on several key physiological aspects of the newborn calf are discussed.
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Affiliation(s)
- Flávio G. Silva
- Veterinary and Animal Research Centre (CECAV), Associate Laboratory of Animal and Veterinary Science (AL4AnimalS), University of Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal (J.L.C.)
- MED—Mediterranean Institute for Agriculture, Environment and Development & CHANGE—Global Change and Sustainability Institute, Department of Zootechnics, School of Science and Technology, University of Évora, Pólo da Mitra Apartado 94, 7006-554 Évora, Portugal; (A.M.F.P.); (C.C.)
- Center for Research and Development in Agrifood Systems and Sustainability, Polytechnic Institute of Viana do Castelo, Agrarian School of Ponte de Lima, Rua D. Mendo Afonso, 147 Refóios do Lima, 4990-706 Ponte de Lima, Portugal
| | - Severiano R. Silva
- Veterinary and Animal Research Centre (CECAV), Associate Laboratory of Animal and Veterinary Science (AL4AnimalS), University of Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal (J.L.C.)
| | - Alfredo M. F. Pereira
- MED—Mediterranean Institute for Agriculture, Environment and Development & CHANGE—Global Change and Sustainability Institute, Department of Zootechnics, School of Science and Technology, University of Évora, Pólo da Mitra Apartado 94, 7006-554 Évora, Portugal; (A.M.F.P.); (C.C.)
| | - Joaquim Lima Cerqueira
- Veterinary and Animal Research Centre (CECAV), Associate Laboratory of Animal and Veterinary Science (AL4AnimalS), University of Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal (J.L.C.)
- Center for Research and Development in Agrifood Systems and Sustainability, Polytechnic Institute of Viana do Castelo, Agrarian School of Ponte de Lima, Rua D. Mendo Afonso, 147 Refóios do Lima, 4990-706 Ponte de Lima, Portugal
| | - Cristina Conceição
- MED—Mediterranean Institute for Agriculture, Environment and Development & CHANGE—Global Change and Sustainability Institute, Department of Zootechnics, School of Science and Technology, University of Évora, Pólo da Mitra Apartado 94, 7006-554 Évora, Portugal; (A.M.F.P.); (C.C.)
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Ceja G, Boerman JP, Neves RC, Jorgensen MW, Johnson JS. l-Glutamine supplementation reduces gastrointestinal permeability and biomarkers of physiological stress in preweaning Holstein heifer calves. J Dairy Sci 2023; 106:9663-9676. [PMID: 37641349 DOI: 10.3168/jds.2023-23334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 05/16/2023] [Indexed: 08/31/2023]
Abstract
l-Glutamine supplementation improves gastrointestinal and immune function in dairy calves during controlled immune and stress challenges. However, it is unknown whether supplementing milk replacer (MR) with l-glutamine improves preweaning dairy calf health and welfare under production conditions. Therefore, the study objective was to evaluate the effects of supplementing MR with l-glutamine on gastrointestinal permeability, immune function, growth performance, postabsorptive metabolic biomarkers, and physiological stress response in preweaning dairy calves. In 3 repetitions, Holstein heifer calves (n = 30; 1.5 ± 0.5 d old; 37.1 ± 0.86 kg body weight) were blocked by serum total protein, body weight, and age, and provided MR (3.8 L/calf per d; 24% CP, 17% fat, 12.5% solids) supplemented with l-glutamine (GLN; 10g/kg MR powder; n = 5 calves/repetition) or nonsupplemented (NSMR; n = 5 calves/repetition). Calves were individually housed with ad libitum starter grain and water access until weaning (56.4 ± 0.5 d old). At 1 and 6 wk of age, urinary catheters were placed, and calves were orally dosed with 1 L of chromium (Cr)-EDTA. Urine samples were collected over a 24-h period for Cr output analysis as an in vivo biomarker of gastrointestinal permeability. Blood was collected on study d 1, 5, 7, 14, 21, 42, and 56 to measure white blood cell counts, cortisol, insulin, glucose, nonesterified fatty acids, serum amyloid A, haptoglobin, and neutrophil: lymphocytes. Two study intervals were used in the statistical analyses, representing greater (P1; wk 1-3) and reduced (P2; wk 4-8) enteric disease susceptibility. Data were analyzed using PROC GLIMMIX in SAS 9.4 (SAS Institute Inc.) with calf as the experimental unit. Overall, total urinary Cr output was reduced in GLN versus NSMR calves. Total Cr output was reduced at 1 wk of age in GLN versus NSMR calves, but no differences were detected at 6 wk of age. Neutrophil:lymphocyte was decreased both overall and during P2 in GLN versus NSMR calves, and neutrophil counts tended to be reduced in GLN versus NSMR calves during P2. No MR treatment differences were detected for average daily feed intake, average daily gain, body measurements, postabsorptive metabolic biomarkers, disease scores, and therapeutic treatments between GLN and NSMR calves. In summary, l-glutamine supplementation reduced gastrointestinal permeability and biomarkers of physiological stress in preweaning Holstein heifer calves.
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Affiliation(s)
- Guadalupe Ceja
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907; USDA-Agricultural Research Service (ARS) Livestock Behavior Research Unit, West Lafayette, IN 47907
| | | | - Rafael C Neves
- Department of Veterinary Clinical Sciences, Purdue University, West Lafayette, IN 47907
| | - Matthew W Jorgensen
- USDA-Agricultural Research Service (ARS) Livestock Behavior Research Unit, West Lafayette, IN 47907
| | - Jay S Johnson
- USDA-Agricultural Research Service (ARS) Livestock Behavior Research Unit, West Lafayette, IN 47907.
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Wang S, Kong F, Liu J, Xia J, Du W, Li S, Wang W. Comparative Analysis of Rumen Microbiota Composition in Dairy Cows with Simple Indigestion and Healthy Cows. Microorganisms 2023; 11:2673. [PMID: 38004685 PMCID: PMC10672840 DOI: 10.3390/microorganisms11112673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/18/2023] [Accepted: 10/26/2023] [Indexed: 11/26/2023] Open
Abstract
Simple indigestion in cows leads to substantial economic losses in the dairy industry. Despite ongoing efforts, an effective treatment for this issue remains elusive. Previous studies have emphasized the vital role of rumen microbes in maintaining ruminant health. To deepen our comprehension of the intricate interplay between rumen microbiota and simple indigestion, we undertook a study involving the analysis of rumen fluid from eight cows with simple indigestion and ten healthy cows. Additionally, we collected data pertaining to milk production, rumination behavior, and rumen characteristics. The results showed that cows with simple indigestion displayed significantly lower milk yield, reduced rumination duration, and weakened rumen contraction when contrasted with the healthy cows (p < 0.05). However, no significant difference in microbiota α-diversity emerged (p > 0.05). Principal coordinate analysis (PCoA) illuminated substantial variations in rumen microbial structure among the two groups (p < 0.05). Further analysis spotlighted distinctive bacteria in the rumen of the cows with indigestion, including Allisonella, Synergistes, Megasphaera, Clostridium_XIVb, Campylobacter, and Acidaminococcus. In contrast, Coraliomargarita, Syntrophococcus, and Coprococcus are the dominant bacterial genera in the rumen of healthy dairy cows. Importantly, these key bacterial genera also dominated the overarching microbial interaction network. The observation suggests that changes in the abundance of these dominant bacterial genera potentially underlie the principal etiology of cows with simple indigestion. The present findings can provide insights into simple indigestion prevention and treatment in dairy cows.
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Affiliation(s)
| | | | | | | | | | | | - Wei Wang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (S.W.); (F.K.); (J.L.); (J.X.); (W.D.); (S.L.)
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Wu Q, Chen H, Zhang F, Wang W, Xiong F, Liu Y, Lv L, Li W, Bo Y, Yang H. Cysteamine Supplementation In Vitro Remarkably Promoted Rumen Fermentation Efficiency towards Propionate Production via Prevotella Enrichment and Enhancing Antioxidant Capacity. Antioxidants (Basel) 2022; 11:antiox11112233. [PMID: 36421419 PMCID: PMC9686782 DOI: 10.3390/antiox11112233] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 11/04/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Cysteamine (CS) is a vital antioxidant product and nutritional regulator that improves the productive performance of animals. A 2 × 4 factorial in vitro experiment was performed to determine the effect of the CS supplementation levels of 0, 20, 40, and 60 mg/g, based on substrate weight, on the ruminal fermentation, antioxidant capacity, and microorganisms of a high-forage substrate (HF, forage:corn meal = 7:3) in the Statistical Analysis System Institute. After 48 h of incubation, the in vitro dry matter disappearance and gas production in the LF group were higher when compared with a low-forage substrate (LF, forge hay:corn meal = 3:7), which was analyzed via the use of the MIXED procedure of the HF group, and these increased linearly with the increasing CS supplementation (p < 0.01). With regard to rumen fermentation, the pH and acetate were lower in the LF group compared to the HF group (p < 0.01). However, the ammonia N, microbial crude protein, total volatile fatty acids (VFA), and propionate in the LF group were greater than those in the HF group (p < 0.05). With the CS supplementation increasing, the pH, ammonia N, acetate, and A:P decreased linearly, while the microbial crude protein, total VFA, and propionate increased linearly (p < 0.01). Greater antioxidant capacity was observed in the LF group, and the increasing CS supplementation linearly increased the superoxide dismutase, catalase, glutathione peroxidase, total antioxidant capacity, glutathione, and glutathione reductase, while it decreased the malondialdehyde (p < 0.05). No difference occurred in the ruminal bacteria alpha diversity with the increasing CS supplementation, but it was higher in the LF group than in the HF group (p < 0.01). Based on the rumen bacterial community, a higher proportion of Bacteroidota, instead of Firmicutes, was in the LF group than in the HF group. Furthermore, increasing the CS supplementation linearly increased the relative abundance of Prevotella, norank_f_F082, and Prevotellaceae_UCG-001 under the two substrates (p < 0.05). Prevotella, norank_f_F082, and Prevotellaceae_UCG-001 were positively correlated with gas production, rumen fermentation, and antioxidant capacity in a Spearman correlation analysis (r > 0.31, p < 0.05). Overall, a CS supplementation of not less than 20 mg/g based on substrate weight enhanced the rumen fermentation and rumen antioxidant capacity of the fermentation system, and it guided the rumen fermentation towards glucogenic propionate by enriching the Prevotella in Bacteroidetes.
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Affiliation(s)
- Qichao Wu
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Hewei Chen
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Fan Zhang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Weikang Wang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Fengliang Xiong
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Yingyi Liu
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Liangkang Lv
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Wenjuan Li
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
| | - Yukun Bo
- Animal Husbandry Technology Promotion Institution of Zhangjiakou, Zhangjiakou 075000, China
| | - Hongjian Yang
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agri-Cultural University, Beijing 100193, China
- Correspondence:
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Wang J, Si W, Du Z, Zhang J, Xue M. Antioxidants in Animal Feed. Antioxidants (Basel) 2022; 11:antiox11091760. [PMID: 36139834 PMCID: PMC9495651 DOI: 10.3390/antiox11091760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 08/22/2022] [Accepted: 09/02/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
- Jie Wang
- National Aquafeed Safety Assessment Center, Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Wei Si
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zhenyu Du
- School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Junmin Zhang
- State Key Laboratory of Animal Nutrition, Institute of Animal Sciences of Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Min Xue
- National Aquafeed Safety Assessment Center, Institute of Feed Research, Chinese Academy of Agricultural Sciences, Beijing 100081, China
- Correspondence:
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Early Stepdown Weaning of Dairy Calves with Glutamine and Branched-Chain Amino Acid Supplementations. Animals (Basel) 2022; 12:ani12121474. [PMID: 35739810 PMCID: PMC9219432 DOI: 10.3390/ani12121474] [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: 05/08/2022] [Revised: 05/31/2022] [Accepted: 06/05/2022] [Indexed: 11/25/2022] Open
Abstract
Simple Summary We demonstrated previously that supplementation of glutamine (Gln) at 2.0% of dry matter intake (DMI) increased the rate at which dairy calves achieved ≥1.0 kg/d starter feed intake (SFI) during weaning. Because Gln supplements at <1.0% of DMI or branched-chain amino acid (BCAA) supplements have been shown to improve the performance of weaning piglets, we examined the effects of a lower dose of Gln (8.0 g/d equivalent to 1% of DMI) alone or in combination with BCAA supplementations on SFI and average daily gain (ADG) in this study. Amino acids did not affect SFI or ADG during the supplementations but decreased post-weaning SFI in an additive manner even though the ADG was not affected. The blood analysis on the last day of supplementations revealed a possibility for the Gln and BCAA supplementations to suppress SFI through leptin and serotonin secreted by the gastrointestinal tract. Abstract The study objective was to examine the effects of supplementing Gln and BCAA on the SFI and ADG of weaning dairy calves. Holstein heifer calves (11 calves /treatment) at 35 d of age were assigned to: (1) no amino acids (CTL), (2) Gln (8.0 g/d) alone (GLN), or (3) Gln (8.0 g/d) and BCAA (GLNB; 17.0, 10.0, and 11.0 g/d leucine, isoleucine, and valine, respectively) supplementations in whole milk during a stepdown weaning scheme. Calves were weaned completely once they achieved ≥1.0 kg/d SFI. Neither GLN nor GLNB affected SFI or ADG in the first week during weaning. The GLNB decreased SFI compared to CTL, but the SFI was similar between CTL and GLN in the remainder of the weaning scheme. All calves were weaned at 50 d of age. The SFI of GLNB was lower than that of GLN, and the SFI of both GLN and GLNB were lower than CTL post-weaning. The decreased SFI did not alter ADG during weaning or post-weaning. The GLNB tended to have higher plasma leptin and lower plasma serotonin concentrations compared to CTL. Glutamine and BCAA seem to affect the SFI of calves by modulating the secretions of endocrine cells in the gastrointestinal tract.
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