UNDERSTANDING FEED-GRADE CALCIUM PHOSPHATE SOURCES “TRI-CALCIUM PHOSPHATE”
(MORE THAN JUST A SOURCE OF PHOSPHORUS)
In the last issue of Milwhite’s Journal it was mentioned that tricalcium phosphate (TCP), commonly referred to as defluorinated phosphate (DFP), is associated with additional benefits when selected as a feed ingredient which go far beyond its contribution of P and Ca to an animal’s diet. It is because of these benefits that TCP is preferred by many poultry nutritionists as the source of P in broiler diets. Since all of the TCP produced world-wide originates from P deposits on the earth’s surface, it is appropriate to present a brief explanation of the origin of all P on our planet. All of the P on the earth’s surface originated from igneous rock deposits formed when molten rock (lava), from volcanic activity, solidified. Following hundreds of millions of years of geologic exposure to different types of weathering and transport over the earth, the P in these original deposits ended up in today’s world-wide commercial phosphate deposits mostly in the form of the calcium phosphate-rich mineral known as apatite, as well as in marine, river and other P rich rocks. It has been estimated that approximately 80% of the world-wide commercially mined phosphates are used as agricultural fertilizers and 15% are used in detergents, industrial products and food additives. The remaining 5% of the phosphates are used to produce feed-grade phosphate supplements for use in diets throughout the animal industry. Of this 5%, approximately 4.5% (i.e., 90%) is used to manufacture monocalcium and dicalcium phosphate. Therefore, only about 0.5% (i.e., 10%) of the world-wide phosphate being mined each year is used in animal feed as TCP.
ADDITIONAL BENEFITS OF USING TCP AS A DIETARY PHOSPHORUS SOURCE
All of the major commercially available high quality phosphate sources supplied to the animal feed industry are rigorously monitored by the manufacturers to ensure that they meet quality control standards. This provides assurance to the feed industry that the bioavailability of the P in the final product is high. Competent nutritionists are concerned about the bioavailability of P and other vital minerals in these phosphate supplements as well as the concentrations of toxic elements such as As, Pb and Cd. Experienced nutritionists look beyond the positive bioavailability data and seek out other reasons to select one product over another. The following is a brief summary about notable properties of TCP that should be given important consideration by nutritionists when choosing a phosphate source for use in diet formulation. Generally, the guaranteed minimum analysis of P, Ca and Na in high quality feed-grade TCP is reported as 18,32 and 5%, respectively, with a P:F ratio of at least 100:1 which is required when a product is legally labeled as being “defluorinated”. Also, the relative bioavailability of the P in TCP is normally reported to be above 93% and this value, or a slightly higher value, is used when formulating feeds.
DFP IMPROVES THE EFFICIENCY OF PELLETING: A major expense in the manufacture of animal feed is the high energy cost, which is especially true for pelleted feed. In 1981, Dr. Keith Behnke (Professor Emeritus, Kansas State University, USA) reported, in the Feedstuffs reference presented below, results of several replicated controlled pelleting experiments designed to identify the true differences that existed in the ability of various feedgrade phosphate sources to enhance the pelleting process. A significant increase in the production rate and energy efficiency resulted from the use of feed-grade DFP products instead of the monocalcium and dicalcium phosphate products. Dr. Behnke estimated that the use of a DFP product would result in a 20 to 30% decrease in time required to produce pellets and a savings of as much as 12% in energy consumption. Since DFP is a product manufactured from ground raw rock phosphate mined directly from the earth, Dr. Behnke concluded that the improved efficiency in time and energy is a result of the abrasive physical properties of DFP and this was the major factor responsible for maintaining a clean die-hole as the conditioned feed was being forced through the pellet die.
THE SPACE SAVING CONTRIBUTION OF Ca and Na in TCP: Nutritionists are very concerned with space limitations when formulating diets, especially for broilers and pigs because of the nutrient/energy dense diets they require. This is especially true in countries where energy sources are expensive. In this respect, the significance of TCP as a P source is easily realized when the computer considers TCP’s contribution of Ca and Na to the diet. In this case, the computer formulation program will select and use less of the cheaper limestone which is to be used only as a source of Ca. By using TCP and removing some of the limestone, which is 38% Ca in the form of CaCO3, provides more formulation space for nutrients and energy. The reason for this is because 62% of the weight of CaCO3 is “CO3” which is not contributing nutritionally to the diet and contributes greatly to energy/nutrient dilution. The same can be said for the bicarbonate in feed-grade sodium bicarbonate which is reported to contain 27% Na and 73% bicarbonate. The contribution of Na from TCP also allows for the use of less salt (NaCl) which contains 40% Na and 60% Cl and is important when nutritionists desire to minimize Na and/or Cl intake. For instance, it is a common practice in the turkey industry to use sodium bicarbonate in the diet in order to lower Cl which is being furnished by salt and thus, help prevent loose droppings and wet litter. Here is an example of where the Na contributed by using DFP lessens the cost of the diet by allowing for the use of less sodium bicarbonate which is more expensive. There is no dietary dilution when using TCP as a P source because the Na and the Ca are nutritionally valuable.
At times when it is desirable to improve performance by increasing dietary Na
without increasing Cl, such as when the ionophore coccidiostat like monensin is used, the
contribution of Na in DFP is a valuable asset to the nutritionist.
OTHER SITUATIONS WHERE DFP CONTRIBUTES TO BETTER POULTRY PERFORMANCE: Acidity (acidosis) is not promoted when DFP is used as the P source in a diet. This is important because there are various situations in egg-type and meat type poultry where deviations from a normal acid-base balance leads to metabolic complications related to vital processes involved in growth, immunity, bone formation, egg production, egg shell quality and survival during heat stress. The following is only a brief mention of several situations which serve to illustrate how using DFP assists in overcoming many of the negative impacts that acidosis may have on bird performance. In body fluids the electrolytes Na+ and K+ are associated with a rise in pH, whereas, Cl- is associated with lowering pH. Reports in the scientific literature and from flocks of birds in the field document that excess Cl is associated with loose droppings (wet litter), poor egg shell quality and leg problems, especially tibial dyschondroplasia in broilers. Also, a major contributing factor related to a higher incidence of sudden death syndrome and ascites in broilers is excessive intake of Na and Cl. Therefore, it is not surprising why nutritionists would decide to lower dietary salt in this situation and use DFP to supply some of the Na. It is also important in such situations to consider all dietary contributors of Cl, such as choline chloride and L-lysine•HCl, in order to alleviate Cl related problems. Acidosis is also promoted when specific dietary components are metabolized in the body. Metabolic acidosis occurs as a result of feeding diets containing an excess of the monobasic form of calcium phosphate [Ca(H2PO4)2] which happens when feed mill mixing errors occur. Metabolic acidosis is also related to sulfuric acid being formed as the divalent anionic sulfate radical (SO4=) is metabolized as a result of consuming the sulfate form of minerals, methionine and cysteine as well as the sulfur arising from consumption of canola meal. Therefore, lowering Cl by removing some of the salt “opens the door” for DFP to be used in the diet.
From the above discussion it is obvious that along with being an excellent dietary P source there are additional benefits attributed to DFP which are directly related to its Ca and Na content. Along with its space saving advantage, anytime a nutritionist decides to increase Na or to lower the Na and CL content in order to minimize problems, as well as, promote better performance, DFP is able to play an important dietary role.
The information presented in this issue of Milwhite’s Journal was compiled by Dr. Orlando Osuna, Director of Health Science at Milwhite, Inc. and Dr. Richard Miles, Professor Emeritus, University of Florida, Gainesville, FL, USA.
Behnke, K.C. 1981. Pellet mill performance as affected by mineral source. Feedstuffs 53(12) page 34.
For additional information contact Dr. Orlando Osuna at 956-547-1970 firstname.lastname@example.org