RUMINANTS AND NONRUMINANTS Dr Kaushalendra Kumar Assistant Professor Animal Nutrition Bihar Veterinary College BASU Patna India Email drkaushalbvcgmailcom Digestion and absorption of protein in monogastric species ID: 1044961
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1. DIGESTION & METABOLISM OF PROTEIN IN RUMINANTS AND NON-RUMINANTSDr. Kaushalendra KumarAssistant Professor (Animal Nutrition), Bihar Veterinary College, BASU, Patna, IndiaE-mail: drkaushalbvc@gmail.com
2. Digestion and absorption of protein in monogastric speciesDigestion of protein happens in the stomach and duodenum by the action of enzymes;Pepsin (stomach), trypsin and chymotrypsin (pancreas).Breakdown of food proteins into polypeptides & further into many exopeptidases & dipeptidases into amino acids.
3. Gastric digestionPepsin and HCl are principally responsible for gastric digestion.Pepsinogen is the inactive forms of pepsin & HCl activates pepsinogen, convert into pepsin, further hydrolyses peptide bonds.Pepsin also have strong clotting action on milk, & rennin or chymosin, enzyme occurs in the gastric juice of calf & young piglet.Products of protein digestion in the stomach are principally polypeptides of variable chain length & a few amino acids.Cont....
4. Digestion in the small intestineMajority of digestion & absorption happens in the small intestine & primary site is the duodenum & jejunum.However, intestinal digestion comprises of intraluminal & membrane and intracellular digestion.Intraluminal digestionMostly performed by pancreatic enzymes, but some microbial proteases may be involved.Membrane and intracellular digestionDigestion at the external membrane of intestinal mucosa (brush border) and within the small intestine columnar cell.Cont....
5. Some important digestive enzymes of proteinName of enzymesSystematic nameSourceSubstrateEnzymes hydrolysing peptide linksPepsin Gastric mucosa Gastric mucosa Proteins and peptidesChymosin (Rennin) Gastric mucosa (young calves) Gastric mucosa (young calves) Proteins and peptidesTrypsin Pancreas Pancreas Proteins and peptidesChymotrypsin Pancreas Pancreas Proteins and peptidesCarboxypeptidase A (Carboxypeptidase)Peptidyl-L-amino-acid hydrolaseSmall intestine Small intestine PeptidesCarboxypeptidase B (Protaminase) Peptidyl-L-lysine (-L-arginine) hydrolaseSmall intestine Small intestine PeptidesAminopeptidases α-Aminoacyl-peptide hydrolasesSmall intestine Small intestine PeptidesDipeptidases Dipeptide hydrolasesSmall intestine Small intestine DipeptidesCredit: McDonald et al. (2011). Cont....
6. Absorption of ProteinDigested product of proteins available in the lumen of the intestine are free amino acids & small oligo-peptides, Further enter the epithelial cells of the small intestine & are hydrolysed by specific di- & tripeptidases. Some small peptides are absorbed intact and subsequently appear in the portal circulation.Amino acids, subsequently pass into the portal blood, then to the liver, are absorbed from the SI by an active transport mechanism (sodium-dependent), except in glycine, proline and lysine.Cont....
7. Digestion and absorption of protein in ruminantsDietary proteins are hydrolysed to peptides & AA by rumen microbes.Key proteolytic organisms present in rumen are Prevotella ruminicola, Peptostreptococci spp. and protozoa.
8. Factors affecting protein digestibilityPresence of enzyme inhibitors.Heat damage of protein occurs due to Maillard or browning reactionSource of protein affect the digestibility.Amount of fibres present in the diet. Digestive systems development of animals.Cont....
9. Metabolism of proteins Transamination and deamination process
10. Fate of absorbed amino acidsCont....
11. Protein synthesisCont....
12. Significance of protein turnover/metabolismSignificance of protein turnover/metabolismPlay important role in metabolic adaptation such as enzymes, hormones, etc. Accelerate restructuring for growth and others activity (e.g., muscle, collagen).Helps in repairing of cells and tissues. Play crucial role in mobilization/transport of protein during protein-deficiency conditions.It can be used as a source of energy. For removal of faulty molecules or protein from the system.Cont....
13. Factors influencing the body protein turnover/metabolismGenetic variation - species, breeds, strains, etc. Nutrition - quantity and quality of protein and energy sources of diet.Physiological state - productive vs unproductive, pathological state, etc. Age and sex - stage of development and male/female.Different hormones such as; growth hormone (anabolic), insulin (anabolic), thyroid hormones (anabolic and catabolic), testosterone (anabolic), oestrogen (anabolic in ruminants and catabolic in nonruminants), &corticosteroids (catabolic).Cont....
14. THANKSDiscussion..........Questions, if any?