Danielle Pogge

 Chain of amino acids with a specific function  Folding of protein determines function  Enzymes, hormones, structural, etc  Amino acids (20)  Molecules containing an amine group  Essential vs. non-essential  Essential = required in the diet Lysine = 1 st limiting AA; Methionine  Protein expressed as crude protein (CP)  = 6.25 x % N Ex: DDGS, 29% CP = 4.6% N

 Specific uses in the body:  Maintenance = primary goal  Growth  Lactation  Pregnancy (number of lambs)  Wool  Hormones and enzymes  Antibodies

 Ruminant Protein:  N containing feeds, NPN, endogenous Ammonia for microbes Amino acids for animals (SI absorption)  Dependent on:  Stage of production Growth, gestation, lactation  Level of production High vs. low producing  Composition of gain Lean gain vs. fat  Ewes = 9-15% (Highest = Lactation)  Lambs = 11-20% (Highest = creep feeding)  Decrease with age

 Physical barriers  Plant cell walls, cross linking of peptide chains  Feed intake  Rate of passage (ingestion to excretion = ~48 h) Fast = less degradation = more by-pass  Rumen pH  Predation of bacteria  Protozoa = engulf bacteria  Feed processing  Heat damage (increase by-pass/decrease solubility) Maillard Reaction SBM, DDGS, Blood Meal  Chemical damage (formaldehydes, tannins)  Coating (lipid)

 3 “Types” of protein:  Degraded Intake Protein (DIP) Metabolized by microbes in rumen  Microbial Crude Protein (MCP) Microbes themselves Bacteria = ~50% Protozoa = 20-60% Contribute ammonia from protein metabolism  Undegraded Intake Protein (UIP) “By-pass protein” Absorbed in the small intestine  Fate of proteins in a ruminant:  Feed proteins  Peptides  Amino acids (rumen) Undegraded, escaped AA, “by-pass” proteins (SI)

 Quality of protein is determined by the compatibility of AA profile to animals needs  New NRC (Nutrient Requirement Council)  Protein requirement based off % UIP  More UIP = lower total protein requirement Ingredient% CP%UIP Corn7.540 Alfalfa Hay SBM4340 DDGS2762 Blood Meal Urea2870

 Non-protein nitrogen (NPN)  N not associated with protein Free AA, nucleic acids, amines, ammonia, nitrates, nitrites, urea  Ex: Urea (287% CP) 100% degradable in the rumen Providing N for microbes  Feeding NPN:  If inadequate DIP available for microbes  Precautions: Less than 1/3 of total protein intake Requires fermentable energy Increases the S requirement Church, 1988

 DIP = 8-13% Total Digestible Nutrients (TDN)  Below = benefit from NPN  Over = excrete  Ex: 100 lbs SBM = 49 lbs CP, 30 lbs DIP (49 lbs *.65 %DIP) 30 lbs DIP/87 lbs TDN = 34% of TDN % DIP% TDN% CP%BCP%DIP of TDN SBM Dry Corn * Alfalfa Hay Corn Stalks * DDGS Brome Pasture

 Microbial sources of N:  Diet protein  NPN  Recycled N  Microbial synthesis:  Dependent on ammonia and amino acids  Energy Balance available ammonia for bacterial growth  % of microbial protein entering SI:  Low protein diet = ~60%  High protein diet = ~40%  NPN = 100% Church, 1988

 Microbial protein yield = 0.13 lbs MCP/lb TDN  MP yield = TDN x 0.13 Microbial protein: ~80% protein, with digestibility of ~80% in SI  Nutritive value of microbial protein:  Increases value of low quality feed  Decreases value of high quality feed  Can survive on NPN and low amounts of recycled N

 Routes: saliva, across rumen wall, low rumen pH  Dependent on protein in diet  Low CP = increase recycling End of lactation dry diet = important! Intake Protein Protein Ammonia Urea NPN Microbial Protein Metabolizable Protein

 Metabolizable protein = available for metabolism  Absorbed amino acids  Microbial protein (digestible)  Undegraded protein (by-pass, digestible)  Absorption  Active transport: Intestines  Portal blood  Cells Na dependent Exchangers  Amino acid availability for host:  Quality, quantity, and degradation Undegraded protein and microbial protein

Church, 1988

 High producing animals may need a greater percent of escape/bypass protein  Ex. Ewes with triplets Lactation (maximize production) High quality alfalfa + corn for energy  Nutrient use: Low quality forage (corn stalks/straw) Supplement protein High quality forage (alfalfa) Often meets requirements = rarely supplement protein

 Management practices:  Test hays for CP values  Supplement on low quality forages (crop residue)  Sort ewes by production level Lactation = greatest need (lose weight 2-6 weeks of lactation)  Cheap protein sources:  Soybean meal (46.5% CP) $310 = $0.33/lb CP  DDGS (29% CP) $200 = $0.34  Alfalfa Hay (17% CP) $200 = $0.58

Protein intake MilkYieldMilkYield 1.28 TDN 1.86 TDN 2.35 TDN

 Why we care:  Protein deficiencies = reduces production Longer days on feed, decreased milk yield, etc. Depresses microbe function and nutrient digestion  Protein excesses: EXPENSIVE! Increases animal’s maintenance requirement Environmental concerns Increased N excretion and run off  Economics Question: Escape protein = expensive Is it worth it?

 Protein requirements:  Amino acids  Microbial protein  Energy is the limiting factor for protein utilization  Protein deficiency = decreased production  Milk, fertility, gain