1. Feed Processing, and Increasing Forage Utilization Through Protein Supplementation
Francis L. Fluharty, Ph.D.
Department of Animal Sciences
The Ohio State University
Wooster, Ohio

2. Ruminant Nutrition Basics
Rumen bacteria are responsible for digesting feed.
Rumen bacteria digest feed by attaching to the feed particles and releasing enzymes.
Increasing the surface area of feed increases the rate of digestion by allowing more bacteria to attach.
With a forage-based diet, there are approximately 1 to 3 billion bacteria per ml of rumen contents.
With a grain-based diet, there are approximately 8 to 10 billion bacteria per ml of rumen contents.

3. Rumen Contents Average 88% Water

4. “Healthy” Papillae

5. Reticulum and Omasum

6. Omasum and Abomasum

7. Understanding How Nutrients are Used Hierarchy of Nutrient Use
Maintenance
Development
Growth
Lactation
Reproduction
Fattening

8. Forage Particle Size Affects a Ruminant’s Maintenance Energy Requirements
Visceral organs increase in weight as total feed intake, diet forage content, or particle size of the forage increases.
Maintaining visceral organs requires 40 to 50% of an animal’s daily energy intake, and 30 to 40% of an animal’s daily protein intake with a forage based diet.
Decreasing organ weight results in improved feed efficiency and reduces nutrient requirements.

9. Effect of Temperature on DMI, Maintenance Energy and Intake

10. Rate of Passage Through the Rumen
Liquid
4 – 10% / hour (1 to 1.7 times per day)
Solids
Concentrate (grain) particles
2 – 7% / hour (.5 to 1.7 times per day)
Roughage (forage) particles
1 – 6% / hour (.25 to 1.5 times per day)

11. Rate of Passage Through the Rumen is Affected by:
Level of feed intake
Higher feed intake increases rate of passage.
2. Feed particle size
Smaller feed particles have a faster rate of passage.
Forage:Concentrate Ratio
Liquid rate of passage is faster with a higher percentage of dietary fiber due to increased re-mastication and re-swallowing (ruminating).

12. Why Do We Process Forage?
Ruminant animals in grazing situations need to maximize forage digestion in order to meet their energy and protein requirements.
Factors that limit the animal’s ability to meet their requirements include: forage species, maturity, lignin concentration, and the ruminal ammonia requirements of cellulose digesting bacterial species.
Unlike grain-based diets, there is a time period, referred to as the lag phase, required for cellulose digesting bacteria to attach to forage particles, and the energy available is directly related to surface area.

13. Why Do We Process Forage?
More complete digestion by rumen bacteria due to more surface area for attachment.
More surface area for enzymatic digestion in the small intestine.
Higher levels of feed intake with forage based diets.
Better fermentation with ensiled feeds due to less air space between particles.

14. Why Do We Process Forage?
Better flow of materials through feed conveyors.
Better mixing of the diet that results in less separation in the feed bunk.

15. Problems Associated with Processing Forages
Increased production costs.
Dust and loss of leaf protein.

16. Forage Processing
Digestibility is qualitative, referring to the susceptibility to degradation. In contrast, digestion refers to the extent of degradation.”
Ruminal fiber digestion is a function of the rate of digestion of the forage and the rate of passage of the forage particles from the rumen.
From a practical standpoint with unprocessed forages, the large particle size of mature forage reduces the energy available to the animal.

17. Forage Processing
For digestion to occur, the microorganisms in the rumen must first be associated with the forage, and then attach to the forage.
Digestion normally occurs from the inside of the forage to the outer layers.
Limitations to the speed at which this occurs include the physical and chemical properties of the forage, the moisture level of the forage, time for penetration of the waxes and cuticle layer, and the extent of lignification (Varga and Kolver, 1997).

18. Forage Processing
Undigested feed is broken down through the process of rumination and re-chewing until it is either digested, or small enough to pass from the reticulo-omasal orifice.
Most particles leaving the rumen are smaller than 1mm, although particles as large as 5 cm may leave the rumen (Welch, 1986).
It is, therefore, not hard to understand how reducing the large particle size of many mature forages to 1mm to 5 cm can increase maintenance energy expenditures due to an increase in visceral organ mass and the energy expenditure of rumination and re-chewing.

19. Forage Processing
The conversion of fibrous forages to meat and milk is not efficient, with only 10 to 35% of the energy intake being captured as net energy to the animal, because 20 to 70% of the cellulose may not be digested (Varga and Kolver, 1997).
Research conducted at The Ohio State University found that steers fed a chopped hay based diet gained 2.5 lbs/day while those fed round baled hay (same hay source) in a rack gained less than 1.5 lbs/day.”
(Source:

20. Forage Processing
Williams et al. (1995) harvested wheat forage with a mower conditioner, at an early head stage of maturity, and allowed it to wilt for either 0, 6 or 20 hours prior to being cut with a forage chopper and ensiled.
They reported that wilting for 20 hours resulted in lower fermentation acids, a higher concentration of water-soluble carbohydrates, and improved fiber digestibility compared with either direct-cut or wilting for 6 hours.

21. Forage Processing
Hintz et al. (1999) reported that maceration, an intensive forage conditioning process that shreds forage thus reducing rigidity and increases field drying rates by as much as 300% by disrupting the waxy cuticle layer of the plant and breaking open the stem, resulted in an increase in surface area available for microbial attachment in the rumen.
Results were: a decreased lag time associated with NDF digestion, an increase in NDF digestion, and a decrease in the acetate:propionate ratio, which would be positive for growing and finishing animals.

22. Forage Processing
If corn is $5.04 per bushel, it is $.09 per pound. Likewise, if dried corn gluten feed or distillers dried grains are $180 per ton, they are $.09 per pound. If hay is $180 per ton, it is $.09 per pound.
Normally, the digestibility of corn, corn gluten feed, and distillers dried grains are all much higher than even the highest quality hay.
Therefore, in order for forages to be economically competitive, they must be managed, harvested, and potentially processed to their optimum digestibility.

23. Think in Terms of “OPTIONS”
Ground Corn Stalks
Distillers Grains

24. Think in Terms of “OPTIONS”
As Fed / Mixed Basis: 68% WDG, 24% wheat flour, and 8% wheat straw. Final moisture is around 52%. On a DMB it is about 45% DDG, 41% flour, 14% straw

25. Ruminal Protein Degradation: The Basics

26. Proteins are made from: Amino Acids

28. Protein Functions in the Body
Cell membranes in muscle, nerves, hair, skin
Blood serum protein
Enzymes
Hormones
Antibodies
Muscle

29. Protein Is Needed For:
Nitrogen for microbial fermentation in the rumen.
Protein degraded in the rumen provides NH3 that the bacteria use to grow.
Microbial protein typically provides about half of the amino acids needed by the animal.
Post-ruminal amino acids supplied to the small intestine and absorbed for use by the animal.

30. All Feed Proteins Degraded in the Rumen Become Ammonia
Ammonia = NH3 O ||
Urea = H2N – C – NH2

31. Ruminal Protein and Fiber Degradation
Ruminant animals in grazing situations need to maximize forage digestion in order to increase performance parameters such as average daily gain or milk production.
Degradable intake protein (DIP) has been reported to be the first-limiting nutrient for beef cattle grazing low-quality forages (Köster et al., 1996; Olson et al., 1999; Bandyk et al., 2001).

32. Ruminal Protein and Fiber Degradation
Cellulolytic bacteria prefer ammonia (NH3) as their N source (Russell et al., 1992), so substituting NPN for a portion of the degradable true protein in supplements for range cows should be a viable option (Köster et al., 2002).
However, when DIP sources of protein are fed, the profile of amino acids entering the small intestine closely resembles microbial protein, and amino acids that are limiting in bacterial protein will probably be limiting to the ruminant's production capability (Willms et al., 1991).

33. Ruminal Protein and Fiber Degradation
In production situations where energy is limiting, either because of relatively low-quality forage or in production situations where there is reduced dry matter intake, microbial protein reaching the small intestine may be insufficient to maximize animal growth, and ruminally undegradable intake proteins (UIP, or bypass protein) may be warranted, (Firkins and Fluharty, 2000).
This is because if energy and protein are limiting, there is a reduction in both the number of bacteria and the growth rate of bacteria, which results in a reduction in the amount of ruminal NH3N that can be used for protein synthesis (Satter and Roffler, 1975).

34. Ruminal Protein and Fiber Degradation
Feeding combinations of ruminally available (DIP) protein sources such as urea or soybean meal (SBM) are commonly used in combination with UIP sources that mostly bypass rumen degradation but are available for enzymatic degradation in the small intestine if not over-heated during drying. Common sources of UIP include corn gluten meal (CGM), distillers grains (DG), feather meal (Fth), or fish meal (FM).

35. Bypass Protein
Protein that escapes degradation in the rumen, which is then digested in the abomasum and small intestine and absorbed as amino acids in the small intestine.
The two sources of bypass protein are undigested intake protein (UIP) and rumen microbial protein from bacteria, protozoa, and fungi.

36. Low Bypass Proteins (Under 40% Bypass)
Soybean meal, 20 – 30% on forage diet
Peanut meal
Urea, 0% bypass

37. Medium Bypass Proteins (40 – 60% Bypass)
Soybean meal, ~ 40% bypass with high- concentrate diets.
Cottonseed meal
Dehydrated alfalfa meal
Corn grain
Brewer’s dried grains
Distillers Grains

38. High Bypass Proteins (Greater than 60% Bypass)
Corn gluten meal, 85% bypass
Blood meal, 82 – 92% bypass
Fish meal, 68% bypass

39. Non-enzymatic Browning (Maillard Reaction) HEAT DAMAGED PROTEINS
In the presence of heat and water (such as occurs in the processing of all the plant and animal products from which we get protein supplements), the carboxyl group (COOH) of a sugar is bound to the free amino end of lysine.
If the heat is not excessive, this bond is broken in the acidic conditions of the abomasum, and the amino acids are available in the small intestine (bypass protein).
If the heat is excessive, an artificial, indigestible polymer is formed (heat damaged protein).

40. Heat Damage Varies With Time and Temperature

41. Urea or Non-Protein Nitrogen (NPN): The Most Misunderstood Protein Supplement||
Urea = H2N – C – NH2
Urea has a protein equivalent of 287% protein equivalents on a dry matter basis (NRC, 1996).
Low rumen pH reduces absorption of ammonia to the blood, and reduces the incidence of ammonia toxicity.
When urea is fed, Sulfur (S), Potassium (K), and Phosphorus (P) must be supplemented.

42. Urea or Non-Protein Nitrogen (NPN): The Most Misunderstood Protein Supplement
Urea is used to:
1. Increase diet organic matter digestion
(Classic example is urea treatment of straw.)
2. Increase microbial protein synthesis
Two Possible Problems with urea at high intakes:
1. Ammonia Toxicity
2. Reduced Feed Intake
Never Exceed Either of These Levels with Urea:
1. 1% of the diet dry matter
2. 1/3 of the total dietary protein

43. Urea or Non-Protein Nitrogen (NPN): The Most Misunderstood Protein Supplement
Williams et al. (1969) and Rush et al. (1976) reported reduced performance in cattle receiving NPN-based supplements compared with cattle receiving true-protein supplements. However, in those studies, NPN was a high proportion of the total supplemental N.
The basal diets that Williams et al. (1969) used contained 4% or 12.1% urea.
Rush et al. (1976) fed 30% protein supplements, based on molasses, with half of the CP coming from NPN.

44. Urea or Non-Protein Nitrogen (NPN): The Most Misunderstood Protein Supplement
However, not all studies with NPN give the same results. In another series of studies, urea or biuret provided 50% of the nitrogen in 30% CP dry supplements, or urea provided 94% of the nitrogen in 30% CP liquid supplements with molasses. In these studies, cow winter weight loss, cow summer weight gain, and calf performance were not different (P > .50) for cows fed natural protein or liquid supplements (Rush and Totusek, 1976).

45. Urea or Non-Protein Nitrogen (NPN): The Most Misunderstood Protein Supplement
Hersom (2007) suggested that the improvement in performance which occurs with the addition of protein to diets of ruminants being fed low-quality forage occurs due to a correcting of a protein/N deficiency in the diet, resulting in a better synchronization of the supply of energy and protein in the rumen, and in many cases occurs regardless of the source of protein, although increasing the proportion of natural protein often improves animal performance.

46. Urea or Non-Protein Nitrogen (NPN): The Most Misunderstood Protein Supplement
Currier et al. (2004) used cows in the last third of gestation to compare the difference between urea at 5.2% of supplement DM or biuret at 6.1% of supplement DM in diets where NPN provided 90% of the estimated DIP requirement.
Supplements were fed at .04% of the cows’ body weight per day, or roughly .5 lb/d for a 1250 pound cow.
Both NPN sources resulted in greater positive weight and body condition score (BCS) changes compared with the control group, and calf birth weight was not affected by NPN supplementation. The authors concluded that ruminants consuming low-quality forage can effectively use supplemental NPN to maintain nitrogen status and performance in both hand-fed and self-fed situations.

47. Urea or Non-Protein Nitrogen (NPN): The Most Misunderstood Protein Supplement
Köster et al. (2002) suggests that urea could replace between 20 and 40% of the DIP in high-protein supplements, containing 30% protein, without significantly altering supplement palatability or cow and calf performance.

48. In Summary:
Increasing the surface area for bacterial attachment increases both the rate and efficiency of microbial degradation of forages.
Supplying combinations of DIP and UIP could best meet the animal's amino acid requirement through maximizing microbial growth and cellulose digestion, as well as providing amino acids from both microbial and feed origin to the small intestine.