Ruminal Availability of Crude Protein (CP) for Microbial Growth and Digestion


Ruminants have the ability to derive nutrients and energy from fibrous feedstuffs because of the microorganisms that inhabit the digestive tract, particularly those in the rumen and reticulum, consisting of bacteria, protozoa, and fungi. These microbes have nutrient requirements in some ways similar to those of the host animal. Notable among these requirements is the need for nitrogenous compounds or CP that can be degraded by the microbes. If the availability of ruminally degraded CP is low, then microbial growth and(or) digestion is limited, which indirectly limits protein and(or) energy available to the host animal.

The requirement for ruminally available CP has not been extensively studied with goats compared with other ruminant species. For beef cattle, without considering ruminal recycling of nitrogen, the requirement of consumed ruminally degradable CP, or degraded intake protein (DIP), has been suggested as 13% of total digestible nutrient (TDN) intake (NRC, 2000). If recycling is also accounted for, the requirement is slightly lower (e.g., 10% of TDN). It has been suggested that ruminal nitrogen recycling is more extensive in goats compared with other ruminant species (Silanikove, 2000), suggesting that the DIP requirement might be lower. In this regard, Soto-Navarro et al. (2003) did not observe limitations in digestion or microbial growth with dietary DIP levels as low as 7% of TDN intake. However, to be conservative and as a safety factor, this calculator estimates the DIP requirement as 9% of TDN intake.

In order to estimate the DIP requirement, it is necessary to know feed intake and concentrations of TDN or metabolizable energy (ME) in the diet. To evaluate whether or not the DIP level in the diet is adequate to allow unhindered microbial growth and digestion, it is also necessary to estimate the concentration of DIP. This is determined from concentrations of CP in dry matter (DM) and DIP in CP. DIP concentrations are listed in the table given below for various feedstuffs.

Use this DIP calculator to estimate the daily requirement of DIP for all classes of goats. Enter the data into the table below and then click the Calculate DIP Requirement button. The results will be displayed in the table at the bottom of the page. The requirements are given in the first set of three boxes and intakes are in the second set. If values in the second set of boxes are less than in the first, then there is a deficiency of DIP that might limit microbial growth and(or) digestion. Hence, the formulation of the diet should be altered to correct this deficiency.

As an example, let’s assume 1 kg of DM intake and a dietary ME concentration of 10 MJ/kg DM, which equates to a TDN concentration of 63.8%. This results in a DIP requirement of 57.4 g (1000 g DM intake x 0.638 x 0.09) or 5.74% of DM intake. With 10% CP in the diet, and a DIP concentration of 75% of CP, actual DIP intake is 75 g or 7.5% of DM intake (1,000 g DM intake x 10% CP in the diet x 0.75). Hence, the dietary level of DIP is adequate. However, if the dietary CP concentration is 8% of DM and the DIP level is 50%, then DIP intake is inadequate (40 g DIP intake and 4.0% of DM intake).


























1. Enter feed intake (DM; kg)
2.

Enter dietary ME concentration (MJ/kg DM)
or
You can use the TDN calculator below and the ME concentration
will be entered automatically.
3. Enter dietary CP concentration (% DM)
4. Enter dietary concentration of DIP (% CP)








To convert from English to metric
system,
enter your values here.
They will be automatically
entered into the table to the left.
DM intake
(lbs)


    

To estimate the dietary ME concentration, often feed tags list the TDN concentration. Likewise, most commercial feed laboratories estimate the TDN concentration based on various analyses, such as for crude protein and fiber fractions.




The ME concentration can be calculated with these simple formulas:
ME (MJ/kg) = TDN (%) × 0.15104 and
ME (Mcal/kg) = TDN (%) × 0.0361.
Enter TDN (%)
 ME (MJ/kg)
 ME (Mcal/kg)




















DIP requirement (g):
DIP requirement (% DM):
DIP requirement (% CP):
DIP intake (g):
DIP intake (% DM):
DIP intake (% CP):

A number of measurements are necessary to most accurately determine the rumen undegraded protein concentration (UIP) in forages and supplemental concentrates. However, as noted for calculation of MP requirements, knowledge of the general type of feedstuff can allow a adequate estimate of the UIP concentration for most practical purposes. For example, many fresh forage diets would probably have a UIP concentration of 20% (on a total CP basis), which means that 80% of the CP is degraded in the rumen or is DIP. Dried forages would have a slightly higher UIP level (e.g., 30% for grasses). In general, as the dietary level of concentrate increases, the UIP level would increase and the DIP level decreases. Since not a large number of feedstuff UIP and DIP concentrations have been determined with goats, below is a table with DIP levels for cattle (Preston, 2000) that can be used until more values determined with goats become available. Typically, feed tags list the major ingredients, which then can be used along with the table below, to derive a reasonable estimate of the UIP concentration.

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Feedstuff Total CP, % DM DIP, % of total CPTDN, % DM
Alfalfa cubes 18 70 57
Alfalfa, dehydrated,17% CP 19 40 61
Alfalfa, fresh 18 82 61
Alfalfa hay, early bloom 19 84 59
Alfalfa hay, midbloom 17 82 58
Alfalfa hay, full bloom 16 80 54
Alfalfa hay, mature 13 70 50
Alfalfa silage 18 84 55
Alfalfa silage, wilted 22 78 58
Alfalfa leaf meal 28 85 69
Alfalfa stems 11 56 47
Ammonium chloride 163 100 0
Ammonium sulfate 132 100 0
Bahiagrass hay 8 63 51
Bakery product, dried 12 70 90
Barley silage 12 80 59
Barley silage, mature 12 75 58
Barley straw 4 30 43
Barley grain 12 72 84
Barley grain, steam rolled 12 60 84
Beet pulp, wet 9 65 76
Beet pulp, dried 7 56 75
Beet pulp, wet, with molasses 10 75 77
Beet pulp, dried, with molasses 10 66 76
Bermudagrass, Coastal, dehydrated 16 60 62
Bermudagrass hay, Coastal 10 80 56
Bermudagrass hay 10 82 53
Bermudagrass silage 10 85 50
Birdsfoot trefoil, fresh 21 80 66
Birdsfoot trefoil hay 16 78 57
Blood meal 92 20 66
Bluegrass, Kentucky, fresh, early bloom 15 80 69
Brewers grains, wet 28 48 85
Brewers grains, dried 28 42 84
Bromegrass, fresh, immature 15 78 64
Bromegrass hay 10 70 55
Bromegrass haylage 11 74 57
Canarygrass hay 9 74 53
Canola meal, solvent 40 70 71
Citrus pulp, dried 7 62 79
Clover, ladino, fresh 25 80 69
Clover hay, ladino 21 75 61
Clover, red, fresh 18 79 64
Clover hay, red 15 74 55
Clover hay, sweet 16 70 53
Corn, whole plant, pelleted 9 55 63
Corn fodder 9 55 67
Corn stover, mature (stalks) 5 70 59
Corn silage, milk stage 8 82 65
Corn silage, mature, well eared 8 74 72
Corn grain, whole 9 42 87
Corn grain, rolled 9 48 87
Corn grain, flaked 9 43 93
Corn grain, high moisture 10 62 93
Corn and cob meal 9 48 82
Corn cobs 3 50 48
Corn screenings 10 48 91
Corn gluten feed 23 75 81
Corn gluten meal, 41% CP 46 40 85
Corn gluten meal, 60% CP 67 38 89
Cottonoseed, whole 22 62 95
Cottonseed, whole, delinted 23 61 95
Cottonseed hulls 4 55 45
Cottonseed meal, mechanical, 41% CP 45 49 80
Cottonseed meal, solvent, 41% CP 48 60 77
Diammonium phosphate 115 100 0
Distillers grain, wet 28 45 90
Distillers grain, barley 30 44 77
Distillers grain, corn, dry 28 38 90
Distillers grain, corn, wet 29 45 90
Distillers grain, corn with solubles 29 47 90
Distillers corn stillage 22 45 92
Distillers grain, sorghum, dry 32 38 85
Distillers grain, sorghum, wet 32 45 85
Distillers grain, sorghum with solubles 31 47 85
Distillers dried solubles 29 100 88
Fat, animal, poultry, vegetable 00 205
Feather meal, hydrolyzed 86 25 69
Fescue, Kentucky 31, fresh 15 80 64
Fescue hay, Kentucky 31, early bloom 18 78 65
Fescue hay, Kentucky 31, mature 11 70 52
Fish meal 66 40 74
Grass hay 10 70 58
Grass silage 11 76 61
Hominy feed 11 52 89
Lespedeza, fresh, early bloom 16 50 60
Lespedeza hay 14 40 54
Linseed meal, solvent 39 62 76
Meadow hay 7 77 50
Meat and bone meal, porcine/poultry 56 76 72
Molasses, beet 9 100 75
Molasses, cane 5 100 75
Molasses, cane, dried 10 100 74
Molasses, citrus 10 100 77
Molasses, wood, hemicellulose 1 100 76
Monoammonium phosphate 70 100 0
Oat hay 10 75 54
Oat silage 12 79 60
Oat straw 4 60 48
Oat grain 13 81 76
Oat groats 18 85 91
Oat middlings 17 80 90
Oat hulls 4 75 40
Orchardgrass, fresh, early bloom 14 77 65
Orchardgrass hay 10 73 59
Peas, cull 25 78 86
Peanut meal, solvent 50 72 77
Potatoes, cull 10 100 80
Potato waste, wet 7 100 82
Potato waste, dry 8 100 85
Potato waste, wet with lime 5 100 80
Potato waste, filter cake 5 100 77
Poultry byproduct meal 62 51 79
Poultry litter, dried 25 100 64
Poultry manure, dried 28 78 38
Prairie hay 7 63 50
Rice grain 8 70 79
Rice bran 14 70 68
Rice hulls 3 55 13
Rye grass hay 10 60 58
Rye grass silage 14 75 59
Rye grain 12 79 82
Sanfoin hay 14 40 61
Sorghum silage 9 70 59
Sorghum grain (milo), ground 11 43 82
Sorghum grain (milo), flaked 11 38 91
Soybeans, whole 40 72 93
Soybeans, whole, extruded 40 65 93
Soybeans, whole, roasted 40 52 93
Soybean hulls 12 72 77
Soybean meal, solvent, 44% CP 49 68 84
Soybean meal, solvent, 49% CP 54 68 87
Spelt grain 13 73 75
Sudangrass hay 9 70 57
Sudangrass silage 10 72 58
Sunflower seed, meal, solvent 38 73 65
Sunflower seed, meal with hulls 31 65 57
Sunflower seed hulls 4 35 40
Timothy, fresh, pre-bloom 11 80 64
Timothy hay, early bloom 11 78 59
Timothy hay, full bloom 8 70 57
Timothy silage 10 75 59
Triticale grain 14 75 85
Turnip roots 12 100 86
Urea, 46% N 288 100 0
Vetch hay 18 86 58
Wheat, fresh, pasture 20 84 71
Wheat hay 9 75 57
Wheat silage 12 79 59
Wheat straw 3 40 42
Wheat straw, ammoniated 9 75 50
Wheat grain 14 77 88
Wheat grain, hard 14 72 88
Wheat grain, soft 12 77 88
Wheat grain, flaked 14 71 89
Wheat grain, sprouted 12 82 88
Wheat bran 17 73 70
Wheat middlings 19 78 82
Wheat mill run 17 72 75
Wheat shorts 20 75 80
Wheatgrass, crested, fresh, early bloom 11 75 60
Wheatgrass, crested, fresh, full bloom 10 66 55
Wheat grass, crested, hay 10 66 54
Whey, dried 14 85 82

Sources used in this calculation method are:

NRC. 2000. Nutrient Requirements of Beef Cattle, 2000 Update. National Academy Press, Washington, DC.

Preston, R. L. 2000. Typical composition of feeds for cattle and sheep. In: Beef 36(10), 10-20. Intertec Publ. Co. Overland Parks, KS.

Silanikove, N. 2000. The physiological basis of adaptation in goats to harsh environments. Small Ruminant Research 35:181-194.

Soto-Navarro, S. A., A. L. Goetsch, T. Sahlu, R. Puchala, and L. J. Dawson. 2003. Effects of ruminally degraded nitrogen source and level in a high concentrate diet on site of digestion in yearling Boer x Spanish wether goats. Small Ruminant Research. 50:117-128.