1. Is BSE (Bovine Spongiform Encephalopathy, "Mad Cow" disease) a concern?
2. What is the typical amino acid profile of Meat and Bone Meal (MBM)?
3. How digestible are the protein and amino acids in Meat and Bone Meal?
4. How consistent is the nutrient content of Meat and Bone Meal?
5. Is Meat and Bone Meal palatable?
6. Why is heat treatment used to process animal proteins and what benefits does
it offer?
7. What quality assurance programs does Darling International participate in?
8. What are the advantages to stabilizing meat and bone meal for poultry?
Fats and Oils
1.) Dear Dr. Ross,
I see that the fat products that Darling provides are used in animal feeds. What are the benefits of adding fat to animal and poultry feeds?
-Fran
Great question, Fran!
There are many reasons to add fats or oils to animal diets. Numerous reviews have been published on the nutritional value of feed fats for ruminant and non-ruminant animals. Nutritionally, fats are a concentrated source of energy and a source of essential fatty acids. Fats improve palatability, feed efficiency, reproductive efficiency, and the digestibility of certain proteinaceous feeds, as well as alleviate heat stress. Added fats may also reduce dust, lubricate equipment, reduce particle separation and physically improve the feed. There is also evidence that certain fatty acid configurations (i.e. conjugated linoleic acid) may influence nutrient partitioning and have nutraceutical properties.
– Dr. Ross
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2.) Hey Dr. Ross,
I see that Darling has several types of grease, but I am particularly interested in yellow grease. What is the energy value of yellow grease?
-Mike
Thanks for the question, Mike.
Because yellow grease contains a mix of unsaturated and saturated fatty acids (in a ratio of about 2.8:1), the dietary energy value is greater than saturated fats such as tallow and comparable to that of poly-unsaturated fats such as soybean oil.
The approximate metabolizable energy (ME) values for yellow grease in non-ruminants feeds are:
Swine - 8584 kcal/kg
Poultry - 8673 kcal/kg
The energy value for ruminants is affected largely by digestibility and feeding level of the fat. Many of the factors affecting fat digestion in non-ruminant animals also apply to post-ruminal fat digestion. The importance of feeding level is greatest when saturated fats are used.
Yellow grease has a favorable unsaturated to saturated fatty acid ratio for high post-ruminal fat digestibility. Thus, the true energy value of yellow grease is probably greater than the values published in beef cattle and dairy feeding guides. Some dairy studies suggest the ME level of yellow grease to be between 8.0 and 9.0 Mcal/kg, which is similar to the ME value listed for poultry and swine.
-Dr. Ross
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3.) Dear Dr. Ross,
I want to be careful about what I feed animals, so can you tell me if dioxins are a concern in feed fats?
-Rosie
Good question, Rosie!
Dioxins are present in minute levels in all forms of life and products and are largely produced by industrial processes, but can also result from natural phenomena such as volcanic eruptions and forest fires. The rendering process per se does not produce dioxins in rendered products.
Yellow grease consists primarily of recycled restaurant grease and is derived from fats and oils inspected and approved by the United States Department of Agriculture for use as or in the preparation of food. The collection and processing procedures used in recycling restaurant grease do not produce dioxins.
Dioxins can conceivably enter the animal feed chain by either accidental or fraudulent adulteration of raw materials used in feed fat production. To overcome this threat to the feed industry, Darling International Inc. developed the Clean Star™ grease collection system to reduce contamination.
Darling International Inc. tests each shipment of fat or grease to insure compliance with federal government tolerances for pesticides and other toxic substances, including PCB's. Elevated PCB levels are accepted as indicators of potential dioxin contamination. The European Commission accepts PCB testing as a means of detecting dioxin adulteration of food and feed. The low cost and rapid turnaround of a PCB test allows for its routine use. Should elevated levels of PCB's be encountered, then a specific test for dioxin can be carried out.
Darling International Inc. subscribes to the quality control and biosecurity practices mandated in the ISO 9002 and HACCP programs. Darling International Inc. is committed to producing quality products that are safe for use as animal feeds and feed ingredients.
-Dr. Ross
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4.) Dr. Ross,
Can you tell me what factors affect fat digestibility?
-David
Sure, David!
A few of the factors that influence the digestibility (and therefore greatly influence the ME value of a fat) are listed below.
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Interactions between fat and nutrients in the diet.
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Interactions among fat sources (i.e. saturated by unsaturated interactions)
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Length of the fatty acid chains
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Degree of saturation of the fat source(s)
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Location of the saturated fatty acids on the glycerol molecule.
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Feeding level (effect decreases as saturation decreases)
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Intestinal factors (such as pH, bile, lipase activity, etc).
-Dr. Ross
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5.) Dr. Ross,
I want to know what feed type is best for my animals. Is there data comparing yellow grease to other feed fats for livestock and poultry?
-Susan
Susan,
Some data does exist, but the number of published comparative studies is limited. Integrators and consulting nutritionists have used on-farm studies to confirm the efficacy of yellow grease. However, their data are proprietary, but must have been positive because yellow grease has been readily accepted in the United States as a good quality source of feed fat. Yellow grease is one of the major sources of feed fat in poultry, swine and cattle rations. Data from a few published comparative studies are shown below.
A Comparison of Poultry Fat and Yellow Grease Fed to Broiler Chicks for 21 Days
a Ouart et al. (1992). Chicks were fed a corn-soybean meal diet with 5% added fat as poultry fat and (or) yellow grease. Treatment means did not differ (P > .10)
b Poultry fat contained 10% FFA, 1.4 meq/kg PV and 108 ppm ethoxyquin.
c Yellow grease contained 19.4% FFA, 4.3 meq/kg PV and 109 ppm ethoxyquin
Effects of Feeding 2% Tallow and (or) Yellow Grease to Holstein Cows During Mid-Lactation.a
aAvila et al. 2000.
bU/S = unsaturated to saturated fatty acid ratio.
cPostruminal fatty acid absorption.
d4% fat corrected milk production.
-Dr. Ross
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6.) Hey Dr. Ross,
Is the FFA level in yellow grease a concern?
-Sharon
Thanks for asking, Sharon.
Free Fatty Acids (FFA, %) are a measure of fatty acids not esterified to glycerol. Moisture, time and temperature interact to produce free fatty acids by catalyzing triglyceride hydrolysis. This is why restaurant greases (yellow grease) have a higher maximum for FFA than the grades of tallow. Some fat sources have very high FFA levels as a result of industrial hydrolysis of the parent stock. Free fatty acid levels have little effect on the nutritional value of feed fats. However, free fatty acids are susceptible to oxidation and rancidity. The importance of stabilizing fats with an antioxidant increases as the % FFA increases.
The effects of FFA levels on animal performance have been studied in all major livestock species (see figure below). Free Fatty acids have little effect at levels typical for many feed fats (i.e. less than 20%). Even when the FFA levels exceed 20%, effects are small and may not be detectable in commercial applications. Never the less, some data suggests that FFA levels dilute the dietary energy value of feed fats and are included in equations used to predict the feed energy value of fats.
-Dr. Ross
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7.) Dear Dr. Ross,
I’m interested in the quality of the fats Darling supplies. Is peroxide value (PV) a good indicator of fat quality?
-Alex
Great question!
Peroxide Values (PV) are required to be determined only on USDA certified edible tallow and lard. The feed industry uses PV to assess the stability or rancidity of fats, by measuring the milliequivalents (meq) of peroxide per kilogram of fat. However, a low PV may not always indicate the absence of rancidity. Typically, peroxides are formed as intermediates in the oxidative pathway. The peroxide pool is not static. When oxidation is allowed to continue unchecked, new peroxides form as others are further degraded. As a result, the PV may plateau and then decline over time. This was demonstrated by exposing choice white grease to heat and oxygen for 11 days (DeRouchey et al., 1999b). Peroxides peaked on day 7 at about 105 meq/kg of fat and subsequently declined to base line values (see figure below).
PVs in excess of about 40 meq/kg of fat for young pigs and 100 meq/kg of fat for poultry, may depress performance. Published data indicating the effects of PV on ruminant animals is not readily available. Antioxidants will prevent further oxidation, but do not reverse the effects once the products of oxidation have formed.
PV of Fat Exposed to Heat and Air for 11 Days
(DeRouchey et al, 1999)
-Dr. Ross
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8.) Dr. Ross,
What is a typical fatty acid profile of yellow grease and other feed fats?
-Maria
Well Maria,
Fatty Acid Profiles may be requested for fats, although their nutritional implications have yet to be fully understood. Aside from the importance of essential fatty acids, it is generally assumed that fatty acids are used almost exclusively as an energy source by the animal. An ideal pattern or profile has not been described for fatty acids as has been reported for amino acids. Example fatty acid profiles for some common fat sources are shown below.
The concentration of polyunsaturated fatty acids may be important because of their effects on fat digestibility for all species and on carcass acceptability of non-ruminant animals. A fatty acid profile is most used to determine the ratio of unsaturated to saturated fatty acids in a fat source. This ratio can be used to predict the dietary energy value of the fat for poultry and swine and may have inferences for ruminants.
Example Fatty Acid Profile for Fat Sources Commonly Used in Animal Feedsa
aAdopted from NRC, 1998.
-Dr. Ross
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9.) Dr. Ross,
Why is the ratio of unsaturated to saturated fatty acids often discussed?
-Percy
Percy,
The ratio of Unsaturated to Saturated Fatty Acids (U:S) is of interest primarily to nonruminant nutritionists for use in regression equations to predict the energy value of feed grade fats and oils. The most widespread usage is in the swine industry because equations were adopted by the NRC and reported in the Nutrient Requirements of Swine (NRC 1998). Using regression equations in this way is compatible with the use of models to predict animal requirements and performance levels. The U:S ratio may also be of value to ruminant nutritionist, although additional work is needed to fully understand the role/fate of unsaturated fatty acids in the rumen and post-rumen. . Many of the factors affecting fat digestion in non-ruminant animals also apply to post-ruminal fat digestion. For example, unsaturated fatty acids improve the digestibility of saturated fatty acid digestibility. However, an over abundance of poly-unsaturated fatty acids can affect carcass acceptability characteristics, especially in non-ruminant animals.
Iodine value is the grams of iodine absorbed by 100 g of fat and is used to estimate the unsaturation of fats. Unsaturated fats have higher iodine values than saturated fats. This rapid and inexpensive test may have value in predicting the unsaturated to saturated fatty acid ratio of feed fats.
The typical unsaturated to saturated fatty acid ratios (U/S) for several common sources of feed fat are shown below.
-Dr. Ross
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10.) Dr. Ross,
There is a lot of information to consider when looking at fats. What are the trading standards or specifications for fats and which are important nutritionally?
-Jack
Refer to the chart below for that answer.
American Fats and Oils Association specifications for tallows and greasesa
aAFOA, 1999
bMoisture maximum 020%. Insoluble impurities maximum 0.05%
cLovibond color 5 1⁄4 inch cell - max 1.5 red. Lard peroxide value 4.0 ME/K max
dTitre minimum, when required, to be negotiated between buyer and seller on a contract by contract basis
eFFA maximum, when required, to be negotiated between buyer and seller on a contract by contract basis.
Specifications for trading fats and oils were developed and continue to be monitored by the American Fats and Oils Association (see Table). These standards are used to facilitate arbitration whenever disputes concerning quality issues develop within the soap, feed and oleochemical industries. This process has worked well because each specification can be quantitatively confirmed by chemical analyses. However, the specifications provide limited nutritional information. Individual contracts for the sale of fats and oils can be written to include additional specifications, provided terms are agreed upon in advance and the buyer agrees to pay for additional analytical costs.
Specification definitions:
Titre minimum - measures the temperature (º C) at which melted fatty acids (obtained by hydrolysis of the fat source) congeal when cooled. Titre affects hardness of soap and is important for fatty acid manufacturing. Nutritionists may use titre as an indicator of the handling properties of a fat source. Generally titre will decrease as the number of unsaturated fatty acids in the fat increase.
Free Fatty Acids (FFA, %) maximum - the percentage of fatty acids not esterified to glycerol. Moisture, time and temperature interact to produce free fatty acids by catalyzing triglyceride hydrolysis. This is why restaurant greases (yellow grease) have a higher maximum for FFA than the grades of tallow. Some fat sources have very high FFA levels as a result of industrial hydrolysis of the parent stock. Free fatty acid levels have little effect on the nutritional value of feed fats. However, free fatty acids are susceptible to oxidation and rancidity. The importance of stabilizing fats with an antioxidant increases as the % FFA increases.
FAC (Fat Analysis Committee) maximum - indicates color using a scale of from 1 (lightest) to 45 (darkest) using only odd numbers. A low FAC color is important to make white colored bath soaps. Because pure fat is almost colorless, high FAC indicates the presence of dissolved foreign material in the fat. Despite this, FAC has no nutritional implications.
R & B (Refined and Bleached) maximum - is a more precise indicator of color than FAC and is used for certain grades of tallow. The Lovibond color is determined on a sample after treatment with alkali and a bleaching earth and reported as red and yellow. While this is important for the oleochemical industry, it has little value to a nutritionist.
MIU (moisture, impurities and unsaponifiables) maximum - has little direct effect on the nutritional value of fats and oils. However, collectively they dilute the energy content and indicate the potential for handling concerns, if the percentage is high enough. High levels of moisture affect shelf life because moisture can accelerate oxidation and rancidity. Impurities (insoluble) include small particles of dirt, hide, hair, protein, etc. and may clog equipment used to handle the fat. Unsaponifiables include sterols, pigments, vitamins, hydrocarbons and other compounds that are dissolved in the fat, but are not hydrolyzable by alkaline saponification. Other tests (i.e. pesticide screens) are used to insure that toxins and other deleterious compounds are absent from the unsaponifiable fraction.
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11.) Dr. Ross,
Is pesticide contamination of fats a concern?
-Matthew
Matthew,
Pesticide analysis screens must be performed on each load or lot of fats and oils. Reputable suppliers have a testing protocol in place to insure that fats and oils used for animal feeds are in compliance with established federal government tolerances for pesticides and other toxic substances, including PCBs.
-Dr. Ross
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PROTEINS
1.)Dr. Ross,
I’ve read a lot lately about BSE (Bovine Spongiform Encephalopathy) or "Mad Cow" disease. Is it a concern?
-Peter
Peter,
The FDA Feed Rule (21 CFR 589.2000) is a key firewall to prevent Bovine Spongiform Encephalopathy (BSE) from spreading in the USA. These regulations banned the feeding of Meat and Bone Meal, made from certain ruminant animal by-products, to cattle and other ruminant animals in the United States. Under these regulations, it is permissible to feed Meat and Bone Meal made from pork or Poultry By-Product Meal to cattle and other ruminant animals. The ban did not affect Blood Meal or Feather Meal. The ban also only affects ruminant animal feeding. Any type of Meat and Bone Meal may be fed to swine, poultry, fish, and companion animals. For more information, please visit BSE Info.
-Dr. Ross
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2.) Dr. Ross,
What is the typical amino acid profile of Meat and Bone Meal (MBM)?
-Jennifer
Jennifer,
The chart below has the amino acid profiles for MBM.
Dr. Ross
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3.) Dr. Ross,
How digestible are the protein and amino acids in Meat and Bone Meal?
-Larry
Well Larry,
We have seen a marked improvement in the digestibility of amino acids during the past 20 years. This improvement is attributed to improved processing and handling of raw material and finished product. The figure below demonstrates this improvement for lysine.
Because of the cost, time and facility requirements associated with conducting amino acid digestibility studies, literature values are used. The following chick data were collected at the University of Illinoisa for average and high quality Meat and Bone Meal (MBM). Amino acid and energy data shown were determined from convential roosters.
a- Parsons, et al. 1997. Poultry Science 76:361.
-Dr. Ross
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4.) Dr. Ross,
You guys must produce a lot of Meat and Bone Meal. How consistent is its nutrient content?
-James
Important question, James!
Consistency is comparable to other protein sources (such as soybean meal) when Meat and Bone Meal is purchased from the same supplier/facility over time. The variation among laboratories can be greater than among sources of ingredients for protein, mineral and amino acid analyses. This is why it is also important to use the same laboratory when evaluating the consistency of an ingredient over time.
-Dr. Ross
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5.) Dr. Ross,
Are Meat and Bone Meal palatable?
-Tom
In a word - Yes.
All historical reports that Meat and Bone Meal was not palatable resulted because the experimental diets were balanced for protein. This resulted in a deficiency of tryptophan, which created an amino acid imbalance. Animals are reluctant to eat a diet that contains an amino acid imbalance, which lead to the false idea that Meat and Bone Meal was unpalatable. Commercial formulations used today balance for several amino acids, including tryptophan. As a result, feed consumption will not be affected by the use of Meat and Bone Meal because amino acid imbalances seldom occur. The data shown below was taken from an in-house study to demonstrate the palatability of Meat and Bone Meal for early-weaned pigs (8 kg).
Level of Meat and Bone Meal
-Dr. Ross
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6.) Dr. Ross,
I see that Darling uses heat for processing. Why is heat treatment used to process animal proteins and what benefits does it offer?
-Joanna
Thanks for asking!
Heat treatment serves several purposes, which benefit both the processor and the end-user. The primary reasons for using heat to process raw materials are to remove moisture and to facilitate fat extraction. The temperatures used are sufficient to kill bacteria, viruses and many other microorganisms, resulting in an aseptic protein product. Heat also sufficiently denatures the protein such that rumen degradability is reduced, without reducing intestinal digestibility for ruminant or non-ruminant animals.
-Dr. Ross
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7.) Dr. Ross,
I like to make sure the products I buy comply with safety standards. What quality assurance programs does Darling International participate in?
-William
We do too, William!
Darling International uses various nationally and internationally recognized programs to supplement its own Quality Control and Quality Assurance efforts. We utilize:
1. ISO 9002 standards for process verification and documentation
2. Hazard Analysis Critical Control Point (HACCP) to control food pathogens
3. Animal Protein Producers Industry (APPI) to administer bio-security programs
4. Fats and Proteins Research Foundation (FPRF) to supplement Darling's own research efforts and conduct industry supported research on the nutritive value of rendered products, bio-security issues, industry issues and non-nutrition uses of rendered products.
-Dr. Ross
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8.) Dr. Ross,
What are the advantages to stabilizing meat and bone meal for poultry?
-Patty
Great question, Patty.
Ethoxyquin is the most common stabilizer used. However, essential nutrients in the feed may also act like stabilizers -- examples are vitamin A and vitamin E.
If the fat in MBM starts going through oxidation, after it is mixed in the feed, then the vitamin A and vitamin E will be destroyed. As a result, the birds may not receive adequate amounts of these vitamins and production efficiency will suffer.
By stabilizing the MBM (as well as any supplemental fat added to the feed) then the vitamin A and vitamin E in the feed will be protected.
If fat becomes rancid enough, the birds can be affected. The first sign observed may be reduced feed consumption. It is unlikely that this would result from feeding rancid MBM because of the relatively low inclusion rates used.
-Dr. Ross
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