North Carolina Cooperative Extension ServiceCollege of Agriculture and Life Sciences

SSSSSWINEWINEWINEWINEWINE News Volume 25, Number 9October, 2002

wineExtension

NC State

ULTIMATE RECYCLING: ASH FROM COM-BUSTION OF SWINE MANURE USED AS AMINERAL SOURCE FOR PIGS

Traditionally, pigs were fed household waste, whiletheir manure was used as a fertilizer for crops. Although itmay not have been realized at the time, this systemresulted in a continuous reuse of minerals such asphosphorus, and thus it prevented environmental prob-lems with these minerals.

In modern production practices, where feedstuffs arebrought in from afar, this cycle is often broken. Mineralsare allowed to accumulate somewhere in the swineproduction system—for example, as precipitated phospho-rus on the bottom of a lagoon. Although this practice isnot in itself harmful, a system in which minerals are reusedis more sustainable.

One method of waste disposal that is receiving a lot ofattention is to combust (or thermally decompose) driedfecal material for recovery of energy, a method that canalso be used to dispose of mortalities. A benefit of thistechnology is that energy is recovered which can be usedto heat buildings, drive a generator, or possibly even beused for the generation of a liquid fuel such as diesel.Another benefit is that bacteria, viruses, and antibioticresidues are destroyed.

This combustion process, though, does not really solvethe mineral problem. Minerals like phosphorus and copperare harvested as ash. Typically, for every 1000 pounds ofdry fecal material, approximately 130 pounds of ash areformed. This ash is rich in minerals, such as phosphorus,calcium, potassium, and magnesium. Currently, it is stilllegal to dispose of the ash in a landfill, but from anenvironmental standpoint, this process is not a preferredsolution. Other options are to use the ash as a fertilizerhigh in P and K.

Ash also can be used as a building material. It can beused in the production of concrete, drywall, and similarproducts. However, the color of the ash is a concern, as itmay affect the color of the building products. Color seemsto depend strongly on the method of combustion used,and incinerators seem to yield ash of suitable color.

One other solution that has received little attention issimply to feed the ash back to the pigs. Pig diets arecommonly fortified with phosphorus, calcium, and micro-minerals such as copper and zinc, and thus there is a needfor these minerals in swine nutrition. To make this solutionpractical, though, the minerals in the ash must be usable(digestible) by the animal, and the ash should not containany mineral at undesirable levels.

To test how practical this method might be, a trialwas done with grower pigs. These pigs were fed atypical grower diet, and their feces were collected anddried using our belt collection system. Subsequently,the dried feces were shipped to Idaho, where they werecombusted for energy recovery. The ash obtained wasshipped back and tested for feed use.

The ash contained high levels of calcium (11.5%) andphosphorus (13.3%), two minerals of great interest inswine production. Phosphorus is especially important,as it is a mineral that is expensive to add to swine diets.The ash also contained micro-minerals, including zinc(0.18%), copper (0.05%), iron (0.73%), and boron(0.01%).

Minerals that are a potential swine health concern arepotassium and selenium. Selenium, though, was foundin very low concentrations and does not seem aconcern. Potassium was present in high concentrations(12%) and should be watched when formulating diets.Another mineral that came in at high levels was magne-sium (5.8%). This mineral is not toxic, though, andrecent research actually suggests that higher levels inswine diets may have benefits for meat quality.

Minerals that were notably low were sodium,chloride, sulfur, and nitrogen. The reasons for this aretwofold:

• The pig excretes these minerals mainly in urine.• Chloride, sulfur, and nitrogen are lost in the flue gas

during combustion.

For nitrogen, this is fortunate, as it would have nobeneficial effect when included in a diet. Chloride,however, will have to be added to the diet, and this canbe easily achieved by adding hydrochloric acid (whichcan be extracted from the flue gas of the combustionsystem). This has another benefit as it reduces the highpH of the ash. In addition, some salt will have to beadded to supply extra sodium.

Thus, if the animal can utilize the minerals in the ash,it could be a valuable supplement to swine diets. Thiswas first evaluated in vitro by assessing the solubilityof ash minerals in water adjusted to pH 2 with hydro-chloric acid, mimicking the environment in the stomach.The results of this test showed that calcium, phospho-rus, potassium, and magnesium are all highly soluble,suggesting that they are also highly digestible.

The next test was to evaluate digestibility in animals.For this, a basal diet was formulated with ingredientsvery low in minerals (corn starch and casein). This basaldiet was supplemented with commercial sources of

minerals, such as dicalcium phosphate, limestone, potassiumchloride, magnesium acetate, and salt, or with ash, hydro-chloric acid, and some salt and limestone in order to generatediets that were nutritionally adequate. These diets weretested for mineral digestibility in grower pigs. In these tests,the percentage of a mineral taken up with the feed butexcreted with the feces is considered indigestible; theremainder is digestible. This assay, though, is only relevantif a mineral is fed below the animal’s requirement, as other-wise, uptake of the mineral in the intestines may be inhibited,leading to an artificially lowered digestibility. Mineralsdigested are either excreted in the urine or accreted by theanimals (part of tissue growth).

Two mistakes were made in this experiment:

• Magnesium acetate was used in the control diet, which, inretrospect, was not a good choice.

• Ash phosphorus contents were underestimated due to anassay error, and the test diet actually contained 40 percentmore phosphorus than desired.

The results of the trial, nonetheless, were very promising.Mineral digestibility of the ash is very close to that of thecommercial mineral sources (see Table 1), even though highlevels of phosphorus in the diet are known to decreasedigestibility of both phosphorus and calcium. Thus, ifproperly formulated diets were used, a digestibility at leastas high as that observed in this trial would be expected. Theonly surprise is magnesium: the magnesium acetate used asa reference was effectively not digestible, while magnesiumin the ash had a digestibility of only 39 percent, possibly asa result of high levels of magnesium in the diet inhibitingmagnesium uptake in the intestines (as in-vitro solubility

October

18-27 North Carolina State FairNorth Carolina State FairgroundsRaleigh, N.C.

22, 23 Managing Forages for Waste Management2.0 credit hours as course number AB02180201Contact Nancy Keith, 336-679-2061

22, 23 Phosphorus Management for Agricultureand the Environment2.0 credit hours as course number AB02180221Contact Nancy Keith, 336-679-2061

30 Carolina Swine Nutrition ConferenceSheraton Imperial HotelResearch Triangle Park, N.C.

30 Healthy Hogs Seminar (Spanish only)Clinton, N.C.

November

4 2002 Option 3 — Land ApplicationTraining and Demonstration Center6.0 credit hours as course number AB02180234Contact Karl Shaffer, 919-515-7538

14 Piedmont Regional Pork ConferenceRoxboro, N.C.

19 Managing Forages for Waste Management2.0 credit hours as course number AB02180201Contact Nancy Keith, 336-679-2061

19 Phosphorus Management for Agricultureand the Environment2.0 credit hours as course number AB02180221Contact Nancy Keith, 336-679-2061

21 Kinston Regional Pork ConferenceKinston, N.C.

26 Wilson Regional Pork ConferenceWilson, N.C.

December

4 2002 Option 5 — Land Application Trainingand Demonstration Center6.0 credit hours as course number AB02180236Contact Karl Shaffer, 919-515-7538

12 Record-Keeping Workshop2.0 credit hours as course number AB11109702Contact Phillip Rowan, 919-757-2801

12 Land Application BMPs1.5 credit hours as course number AB02180219Contact Phillip Rowan, 919-757-2801

12 Odor Regulations Update0.5 credit hour as course number AB01110101Contact Phillip Rowan, 919-757-2801

CALENDAR OF EVENTS

was excellent). This digestibility, though, is more thanadequate from a nutritional standpoint.

These data suggest that ash is an excellent source ofminerals for pigs, and that feeding ash back to pigs may bethe ultimate method for recycling minerals. One importantquestion remaining is whether feeding ash to pigs over timewill lead to a large excess of a certain mineral in the feed thatresults in an even larger excess of this mineral in ash to thepoint that the ash is not suited for use as a feed ingredient.For potassium (and other minerals mainly excreted in urine),this is an unlikely problem, as excess dietary potassium isexcreted in urine. For magnesium, this may become aconcern, but one that may be alleviated through selectiveextraction of magnesium (note that commercial diets willcontain much less ash than our test diets; thus, they are lesslikely to cause a mineral excess).

Our next step is to gather ash from different sources andevaluate it for its nutrient content and digestibility. Providedresults are as encouraging as these data, feeding ash is a realsolution that not only solves the environmental problemswith minerals, but also reduces the need for supplementaland often expensive minerals.

—Theo van Kempen

Table 1. Digestibility of minerals in diets formulatedusing commercial mineral sources and ash.

Commercial Ash Std. Error

P 72.3 63.0 2.3K 92.6 88.8 1.0Ca 76.0 56.5 2.1Mg 2.2 39.1 6.3

Healthy Hogs Seminar will be in Spanish

This year’s Healthy Hogs Seminar, slated for Wednes-day, October 30, at the Sampson Agri-Exposition Center inClinton, will be delivered entirely in Spanish

Over the last 10 years the North Carolina pork industryhas undergone enormous change. One of those changes hasbeen a huge influx of Spanish-speaking workers. In the past,the Healthy Hogs seminars have been delivered in English,but this year we believe it is time to provide the sameeducational opportunity to our Hispanic workers.

The seminar will be delivered entirely in Spanish by peoplewhose first language is Spanish and who are well-recognizedexperts in their fields. There will be no English program.

In addition, the program will start at 2:20 p.m. so thatpeople will be able to complete their on-farm chores beforeattending the seminar. To help us plan, please register early;the first 30 registrants will receive a free copy of the Spanishedition of The Swine AI Book, a $20 value. Registration is $35per person. After the seminar, a Mexican dinner will be served.

Our program committee has developed a comprehensiveprogram focused on the needs of the Hispanic worker.Attendees will leave the seminar understanding:

• The use of all forms of drugs in all stages of productionand the importance of following directions.

• The reproduction cycle of sows, factors influencing thecycle, and the use of hormones.

• The importance of following biosecurity protocol and whyprotocols are written as they are.

• How to work safely.• The importance of production targets and how they are

calculated.• The opportunities in the pork industry for those prepared

to seize the day.• How pigs should be fed and how to manage the feeding

systems.• Safeguarding the welfare of pigs in your care.• Management principles for breeding, farrowing, nursery,

and finishing.

To register or for information, contact Carla McKinney atcarla_mckinney@ncsu.edu or telephone (919) 515-4000. Forfurther information, contact Dr. Morgan Morrow atmorgan_morrow@ncsu.edu

—Morgan Morrow

RICHARD A. (DICK) HAYES

With the death of Dick Hayes at age 73 on August 21, 2002, North Carolina lost a rare and gifted person.He was knowledgeable, energetic, and competitive and was keenly interested in and promoted livestock.Dick graduated from Oklahoma A&M University in 1952 and was associated with Nutrena Feeds, a division ofCargill, in Wilson, N.C. In November 1966 he was appointed as an Extension livestock agent in WilsonCounty. In 1973 he was promoted to county Extension director in Greene County. While in Wilson County, aportable feed grinder-mixer overturned on him, and he never fully recovered from the associated internalinjuries. He took an early medical retirement in 1983. In later years, he sold seed for Asgrow Seed Co.

He helped to promote and improve Wilson’s reputation as home of the top Junior Livestock Show and Saleand high individual sale prices. The county didn”t have a satisfactory arena, so he solicited some telephonepoles, and he and a few producers built a livestock arena. It wasn’t the fanciest one around, but it was ad-equate. In the early 1990s, the Wilson Junior Livestock Show was dedicated to Dick Hayes and Walter Farrior.

Dick trained Junior Livestock Judging Teams that were the envy of livestock agents across the state andhad numerous state winners. Several of his former team members today hold responsible livestock-relatedpositions.

Dick was active as an exhibitor in the steer shows at the North Carolina State Fair. He was so successfulthat some people even suggested barring him from the show. The bottom line is that Dick Hayes was inductedinto the N.C. State Fair Livestock Hall of Fame in 1984.

For 21 years Dick officiated high school athletic events for The North Carolina High School Athletic Asso-ciation. He was a respected official, but was not opposed to calling technical fouls on the bench or even onunruly team supporters.

Dick was a good golfer with a low handicap. The only way some buddies could beat him was to brag on himand tell him he was the longest ball hitter around, just hoping that he would hit the ball too hard and end up witha slice or something.

His family was all boys with Jack, Tom, Bill, and Tim. Several years after his first wife Irene died, hemarried Shelby Langley and added her daughters, Kathy and Penny, to the family by adoption. Most of thoseyears he lived in Saratoga, N.C.

Dick Hayes was a good friend and colleague. He was also an extrovert and had an opinion on almostanything or everything. I’ll miss Dick and his unique character. His kind doesn’t pass this way very often.

— James R. Jones

ON-FARM PERFORMANCE TESTING: The following breeders with validated herds have tested animals in the past 30 days.

Breeder Address Breed

Caswell Farm Unit ........................................... 2415 W. Vernon Ave., Kinston 28501 ........................................................................ XBob Ivey* ............................................................ 314 N.C. 111 S, Goldsboro 27530 ............................................................. L,D,Y,CWWesley Looper* ........................................... 4695 Petra Mill Road, Granite Falls 28630 ...................................................... Y,L,H,D,XThad Sharp, Jr. & Sons ........................................ 5171 N.C. 581 Hwy., Sims 27880 .................................................................... Y,D,XTommy Spruill ....................................................... Rt. 1, Box 149, Columbia 27925 ......................................................................... L,XThomas Farms .................................................. 8251 Oxford Road, Timberlake 27583 ........................................................................ XUCPRS ................................................................ Rt. 2, Box 400, Rocky Mount 27801 ......................................................................... X (Swine Development Center)

*Realtime Ultrasound —Frank Hollowell, David Lee