Effects of Dietary Ingredients On Carcass Quality Measures

Three separate Kansas State University (KSU) research trials confirm that adding fat to swine diets increases carcass iodine values. The exact impact on the carcass depends on the fat source.

In the first experiment, researchers found that adding ingredients high in unsaturated fats, such as dried distiller's grain with solubles (DDGS) or extruded expelled soybean meal (EESM), have a greater effect on iodine value of the carcass fat than choice white grease (CWG), even when the calculated dietary iodine values were similar.

When comparing corn-based vs. sorghum-based diets in a second research trial, KSU researchers concluded that feeding sorghum reduces iodine value when compared to feeding corn. They say sorghum could potentially be used to replace corn when iodine values approach the maximum level.

Results of the third research trial suggested for each 10% increase in DDGS added to the diet, iodine value increases by 1.5 to 3 g./100g., depending on where the fat is stored in the body.

The research trials were based on the knowledge that feeding ingredients containing unsaturated fats can have a large impact on carcass iodine values. Iodine value is a measure of the level of unsaturation of fats, and therefore a measure of fat firmness. Calculating a diet's iodine value appears to underestimate the impact of unsaturated fat sources on carcass fat iodine value as compared to saturated fat sources. This indicates dietary iodine values may not be an accurate predictor of carcass iodine value.

For processors targeting the Japanese market or the fresh belly market, fat softness is becoming a major issue. These processors have measured iodine value of carcass fat and, to date, have asked producers to alter diets to be below a maximum iodine value target. Production costs could further increase if lower-cost ingredients, such as bakery products, DDGS or EESM, must be limited or eliminated from the diets.

In the first research trial, researchers took a look at the impact on finishing pig growth performance and fat quality if choice white grease was added to corn and sorghum-based diets. Sorghum is often an economical replacement for corn in some swine diets. The researchers noted that Triumph Foods, St. Joseph, MO, has set a maximum jowl iodine value of 73.

Previous research showed that adding an unsaturated fat source during any portion of the finishing phase can result in iodine values above 73. Researchers speculated that because sorghum has a lower oil content than corn, a lower carcass iodine value may result.

Researchers used 120 crossbred barrows and gilts with an initial weight of 119.9 lb. in an 83-day experiment. Experimental treatments were arranged based on whether the diet included corn or sorghum, if fat was added and the gender of test animals. The fat options included 0, 2.5 or 5% CWG.

Pigs fed sorghum-based diets had increased average daily gain (ADG) compared to pigs fed corn-based diets. The higher ADG was due to an increase in average daily feed intake (ADFI) for pigs fed sorghum-based diets.

Typically, the researchers say they would expect similar ADG and slightly poorer F/G for pigs fed sorghum-based diets compared to corn-based diets. Pigs fed increasing levels of CWG improved ADG, too.

The results shown in Tables 1 and 2 confirm that added dietary fat improves pig growth. Pigs fed corn-based diets had improved dressing percentage, reduced 10th-rib backfat and improved lean percentage compared with pigs fed sorghum-based diets. The results also confirmed barrows had lower lean percentages than gilts.

The researchers found substituting sorghum for corn in diets for finishing pigs can be an effective way to reduce iodine value without affecting growth.

In the second trial, KSU researchers found that DDGS and EESM can be economical to feed to growing and finishing pigs. However, using these ingredients increases the dietary fat level when they are substituted for corn or soybean meal.

When dietary fat level increases, the result is softer carcass fat. The trial to study the effects of DDGS and EESM on growth performance and fat quality included 120 barrows with an initial weight of 105.7 lb.

Diets included: a corn-soybean meal control diet with no added fat; corn-EESM diet with no added fat; corn-EESM diet with 15% DDGS; corn-soybean meal diet with 15% DDGS and 1.55% CWG; corn-soybean meal diet with 3.25% CWG; and corn-soybean meal diet with 4.7% CWG. Diets were formulated to have three dietary iodine value levels of 42, 55 and 62, to compare the impact of the fat source within dietary iodine levels.

Jowl and backfat samples were collected after 83 days. The results indicated pigs fed the control diet, EESM or 4.7% CWG had increased ADG compared with pigs fed either diet containing 15% DDGS (Tables 3 and 4).

Pigs fed the control diet had increased ADFI compared with all other treatments. Pigs fed the EESM with 15% DDGS and the diets with 4.7% CWG had improved feed/gain compared with pigs fed the control diet and pigs fed DDGS with CWG. Pigs fed high CWG diets had greater loin depth compared with pigs fed low-CWG diets.

Pigs fed either of the diets with 15% DDGS had increased backfat iodine values when compared with pigs fed diets without DDGS. Pigs fed EESM had increased backfat iodine values when compared with the control diet or diets with 3.25 or 4.7% CWG.

Adding DDGS, using EESM or adding CWG to the control diet increased iodine value of jowl fat. Feeding ingredients with higher levels of unsaturated fat, such as EESM and DDGS, had a greater impact on fat iodine value than CWG, even when diets were formulated to similar iodine value levels.

The results confirm that adding fat to finishing diets improves growth performance. Feeding DDGS in this trial resulted in decreased ADG and ADFI. Adding DDGS, EESM or CWG increased iodine value and reduced the percentage of saturated fatty acid.

Feeding ingredients with higher levels of unsaturated fat, such as EESM and DDGS, had a greater impact on fat iodine value than CWG, even when dietary iodine values were similar. Feeding pigs a diet with more unsaturated fat may lead to jowl fat and backfat with more similar iodine values.

In the third trial, KSU researchers used 1,112 pigs in a 78-day trial to evaluate the effects of including DDGS at 0, 5, 10, 15 or 20% of the grow-finish diet.

Previous research has shown that DDGS levels could be fed at up to 30% of the diet before growth performance was reduced. The impact of DDGS on growth performance is blamed on product variability between batches. Variations in palatability are suspected to influence performance.

As noted earlier, DDGS has been shown to impact carcass characteristics by reducing percent yield and carcass weight, while making carcass fat softer and bellies less firm.

The research barn was topped at Day 57 to simulate normal pig marketing under commercial production practices. The three heaviest pigs from all pens were removed and marketed. Six barrows from among the tops were randomly chosen from each treatment to collect data for analysis. The remaining pigs were shipped at the end of the experiment for collection of standard carcass data. Samples were collected and frozen for further processing and analysis.

Overall, ADG and ADFI decreased with increasing DDGS (Table 5). However, the greatest difference in ADG occurred when DDGS was increased from 15 to 20% of the diet. Pigs fed 5% DDGS tended to have improved F/G compared with pigs fed other dietary treatments. There were no differences in live slaughter weight or loin depth. Carcass weight and percent yield decreased with increasing DDGS in the diet. Increasing DDGS tended to decrease backfat and fat free lean index (FFLI).

Backfat, jowl fat and belly fat iodine values and percentage of C 18:2 fatty acid (the major unsaturated fatty acid) increased with increasing the DDGS in both topped pigs (Table 6), and pigs marketed at trial completion (Table 7). Percentage saturated fatty acid in backfat and belly fat decreased with increasing DDGS in both sets of pigs.

Increasing DDGS reduced ADG, carcass weights and percent yield. The reduction in ADG was driven by a reduction in ADFI as DDGS level increased in the diet. The reduced carcass weights equated to a reduction of 4 lb./pig fed the 20% DDGS. Iodine values increased as DDGS levels were increased. For each 10% of DDGS added to the diet iodine value increased by 1.6, 2.4 and 3.0 g./100g. in the jowl fat, backfat and belly fat respectively.

The researchers concluded, based on these results and previously conducted research trials, the linear reduction in yield and increase in iodine value must be considered when determining the economic value of DDGS.

Researchers: Justin M. Benz; Sara K. Lineen; Joel M. DeRouchey; Mike Tokach; Steve Dritz, DVM; Jim Nelssen; and Robert Goodband, Kansas State University. Contact Benz at (785) 532-1270.

Table 1. Main Effects of Adding Fat to Corn and Sorghum-Based Diets on Growth Performancea
Fat Level Source Gender
Added Choice White Grease 0% 2.5% 5% Corn Sorghum Barrows Gilts
Day 0 to 83
Average daily gain, lb. 2.03 2.11 2.19 2.05 2.17 2.12 2.09
Average daily feed intake, lb. 5.72 5.79 5.84 5.65 5.91 5.94 5.62
Feed/gain 2.81 2.75 2.67 2.76 2.73 2.81 2.69
aTotal of 116 pigs (initial weight 119.9 lb.) with two pigs/pen and 10 replicates
Table 2. Main Effects of Adding Fat to Corn and Sorghum-Based Diets on Carcass Performance
Fat Level Source Gender
Choice White Grease 0% 2.5% 5% Corn Sorghum Barrows Gilts
Hot carcass wt., lb. 210.7 214.3 217.2 212.7 215.2 214.8 213.2
Dress, % 72.5 73.2 73.1 73.3 72.5 73.4 72.4
10th-rib backfat, in.b 0.68 0.72 0.78 0.70 0.76 0.75 0.70
Loin depth, in.b 2.41 2.54 2.45 2.47 2.47 2.45 2.48
Last rib backfat, in.b 0.91 0.98 1.00 0.96 0.97 0.97 0.95
Lean, %b 53.6 53.6 52.6 53.6 52.9 52.9 53.6
Backfat iodine value 62.54 66.24 65.94 65.82 63.86 64.70 64.96
Jowl fat iodine value 68.03 69.47 70.48 70.29 68.29 69.51 69.13
Backfat, % 12.50 14.02 13.49 14.37 12.29 13.32 13.30
Jowl fat, % 13.39 13.99 14.19 14.69 12.99 13.95 13.76
Backfat saturated fatty acids, % 41.38 38.72 38.46 39.49 39.67 39.74 39.41
Jowl fat saturated fatty acids, % 36.36 35.29 34.26 35.05 35.60 35.24 35.38
Table 3. Effects of Dried Distiller's Grain with Solubles (DDGS), Extruded Expelled Soybean Meal (EESM) and Choice White Grease (CWG) on Growth Performancea
Day 0 to 82
Average daily gain, lb. 2.08b 2.07b 1.83c 2.00bc 2.04bc 2.18b
Average daily feed intake, lb. 6.37b 5.98c 5.54d 5.92c 5.75cd 5.86cd
Feed/gain 3.17c 2.95bc 2.65b 3.00c 2.88bc 2.74b
aTotal of 120 pigs (initial weight 105.7 lb.) with 10 observations per treatment
bcdTreatments with different superscripts differ P<0.05
eChoice White Grease
Table 4. Effects of Dried Distiller's Grain with Solubles (DDGS), Extruded Expelled Soybean Meal (EESM) and Choice White Grease (CWG) on Carcass Performancea
Loin depth, in. 2.00bc 2.00bc 2.13bc 2.08bc 1.93b 2.19c
Lean, % 50.8 50.9 51.2 51.1 50.6 51.3
Dress, % 73.0 71.7 72.0 73.0 73.1 73.0
Last rib backfat, in 0.94 0.90 0.88 0.94 0.92 0.97
10th-rib backfat, in 0.82 0.78 0.82 0.79 0.78 0.83
Backfat iodine value 59.92b 64.99c 70.78d 69.34d 62.11b 61.82b
Jowl iodine value 64.60b 68.80d 72.30f 70.16e 66.25c 67.09cd
Backfat, % 11.20b 14.48c 18.44d 17.32d 11.80b 11.36b
Jowl, % 11.02b 13.82c 16.17d 14.90cd 11.61b 11.86b
Backfat saturated, fatty acids, % 42.83b 41.06c 38.43b 38.48b 41.03c 40.78c
Jowl saturated fatty acids, % 37.43e 36.07c 34.41b 35.18bc 36.26d 35.48cd
aTotal of 110 pigs
bcdefTreatments with different superscripts differ, P<0.05
eChoice White Grease
Table 5. Effects of Increasing DDGS on Grow-Finish Pig Performance and Carcass Characteristicsa
Item 0 5 10 15 20
Day 0 to 78
Average daily gain, lb. 2.03 2.02 2.02 1.98 1.95
Average daily feed intake, lb. 5.27 5.11 5.22 5.09 5.05
Feed/gain 2.60 2.53 2.59 2.58 2.59
Slaughter weight, lb.b 259.9 259.7 259.6 256.7 256.7
Carcass weight, lb. 196.7 195.9 195.4 193.1 192.7
Yield, % 75.67 75.46 75.39 75.22 75.06
Backfat, in.c 0.73 0.74 0.72 0.71 0.71
Loin depth, in.c 2.31 2.30 2.29 2.26 2.27
FFLI, %cd 49.34 49.45 49.53 49.70 49.65
aA total of 1,112 pigs (initially 110 lb.) with 25 to 28 pigs/pen and nine replications/treatment
bWeight determined at slaughter plant
cData analyzed using carcass weight as a covariate
dFat-free lean index
Table 6. Effects of Increasing DDGS on Fat Quality of Topped Pigsa
Item 0 5 10 15 20
Iodine value, g./100g.
Backfat 67.9 69.3 71.8 72.3 72.3
Jowl fat 69.3 70.3 70.3 71.3 72.9
Belly fat 67.5 69.6 70.8 72.0 73.8
Fatty acids, %
Backfat 13.7 15.2 16.5 17.5 17.6
Jowl fat 13.0 13.9 14.1 15.4 15.8
Belly fat 13.3 14.8 15.8 17.3 17.9
Saturated fatty acids, %
Backfat 36.1 35.1 34.4 34.6 33.7
Jowl fat 33.8 33.6 33.9 33.9 32.5
Belly fat 36.2 35.4 35.1 35.1 33.7
aMeans represent six observations (pigs)/treatment.
Table 7. Effects of Increasing DDGS o n Fat Qualitya
DDGS, % Gender
Item 0 5 10 15 20 Barrows Gilts
Iodine Value, g./100g.
Backfat 68.3 70.0 71.2 72.4 72.8 70.7 71.1
Jowl fat 70.7 70.8 71.9 72.6 73.8 71.6 72.3
Belly fat 70.2 71.5 72.4 73.3 74.5 71.8 72.9
Fatty acids, %
Backfat 14.0 14.9 15.8 17.1 17.6 15.6 16.2
Jowl fat 14.1 14.0 14.9 15.6 16.5 15.0 15.1
Belly fat 14.5 15.3 16.3 16.8 17.9 15.9 16.5
Saturated fatty acids, %
Backfat 36.0 35.0 34.5 34.4 34.5 34.9 34.9
Jowl fat 33.3 33.1 32.8 32.7 32.3 33.2 32.5
Belly fat 34.4 33.8 33.7 33.2 32.9 33.9 33.3
aMeans represent 18 observations (pigs)/treatment.

Larger Litters Don't Result in Increased Weight Variability

Increased litter size results in decreased average birth weights. But larger litters do not increase variability in body weight of the pigs in the litter at birth. Carcass quality is also unaffected by litter size.

Recent analysis suggests that increasing litter size by one piglet reduces average birth weight by 0.22 lb., and doubles the proportion of piglets with a birth weight below 1.8 lb.

The goal of this study was to gauge whether there is a relationship between birth weight and postweaning growth performance on carcass quality. The second question was whether increased litter size caused increased variability in piglet weight at birth and later in life.

Researchers at the Prairie Swine Centre collected data from 98 litters (1,114 piglets). Litters were divided into “small” (3 to 10 piglets born alive), “medium” (11 to 13 born alive) and “large” (14 to 19 born alive). Interestingly, 91% of the total born were born alive in the small and medium groups, while greater than 98% of those born in the large litters were born alive. Approximately 85% of all pigs born alive were weaned.

Average birth weight was 3.5, 2.5 and 3.0 lb. for the small, medium and large groups, respectively. Average birth weight in larger litters was reduced by about 6% compared to average litter size, but did not contribute to greater variation in body weight at birth, nor to reduced market weights.

Average weaning weight was 14.4 lb., which ranged from 3.41 lb. to 23.5 lb.

Dressing weight was 207.5 lb. and was similar between litter sizes.

Since increased litter size did not cause increased variability on body weight at birth or throughout the finishing period, Canadian researchers emphasize there is significant economic advantage in producing more hogs in a swine production unit.

Moreover, in a 600-sow, farrow-to-finish facility, increasing total born from 10 to 12 piglets would generate nearly an additional $14/hog marketed, as more hogs can be spread over all fixed costs.

Researchers: J.F. Patience, A.D. Beaulieu and T. Osmanagic, all of the Prairie Swine Centre (PSC) at Saskatoon, Saskatchewan. Contact the PSC by phone (306) 373-99232, fax (306) 955-2510, or e-mail Kenneth Engele, PSC assistant manager of Information Services, at Ken.Engele@usask.ca.

Table 1. The Effect of Litter Size on the Growth and Variability of Growth
Small ⅓ of litters Medium ⅓ of litters Large ⅓ of litters All Litters
Number of Litters 38 39 21 98
Total Born Alive
Minimum 3 11 14 3
Maximum 10 13 19 19
Total Weaned
Minimum 2 5 2 2
Maximum 10 13 17 17
Body Weight, lb.
Minimum 1.76 1.65 1.65 1.65
Maximum 5.50 5.50 5.17 5.50
Weaning Weight, lb.
Minimum 3.41 4.40 4.51 3.41
Maximum 23.54 21.45 22.22 23.54
Five-Week Weight, lb.
Minimum 18.26 24.97 17.05 17.05
Maximum 73.70 66.11 70.07 73.70
Seven-Week Weight, lb.
Minimum 26.18 41.25 31.90 26.18
Maximum 97.68 96.47 98.78 98.78
First Pull Weight, lb.
Minimum 131.78 144.76 140.14 138.89
Maximum 269.28 260.48 268.84 266.20
Table 2. The Effect of Litter Size on Carcass Quality
Small ⅓ of litters Medium ⅓ of litters Large ⅓ of litters All Litters
Number of Pigs 222 222 199
Dressing Wt., lb.
Minimum, lb. 175.78 166.32 163.46 163.46
Maximum, lb. 175.78 235.84 229.24 235.84
Yield, %
Minimum 55.10 55.20 54.90 54.90
Maximum 64.70 65.40 65.00 65.40
Loin depth, in.
Minimum, in. 1.84 1.76 1.36 1.36
Maximum, in. 3.12 3.24 3.18 3.24
Backfat, in.
Minimum, in. 0.44 0.40 0.44 0.40
Maximum, in. 1.44 1.40 1.30 1.44
Minimum 50.00 50.00 50.00 50.00
Maximum 113.00 113.00 113.00 113.00

Additives to Improve Flowability of DDGS Studied

University of Minnesota (U of M) researchers have found that in-creasing moisture content of dried distiller's grains with solubles (DDGS) from 9% to 12% clearly and significantly reduced the flowability of the feedstuff.

However, the researchers were unable to find agents to help make the DDGS flow through bulk storage containers and transport vehicles without bridging.

DDGS handling challenges have caused some pork producers to stop using the product in swine diets.

Minnesota researchers designed a study to determine if adding flowability agents could make the DDGS flow more smoothly under practical, commercial conditions. The experiment was conducted at a dry-grind ethanol plant built in 2005.

Two sets of treatments made up of different flowability agents and moisture levels were simultaneously evaluated. Four flowability treatments were studied. A control group contained non-treated DDGS.

A grain conditioner called DMX-7 from Delst, Inc., is purported to control moisture migration, thus improving flowability. The other two flowability agents, added in the form of a very fine powder, were calcium carbonate, included at 2%, and a clinoptilolite zeolite, used at 1.25%.

The four flowability treatments were added to DDGS with 9% moisture, expected to flow readily; and DDGS with 12% moisture, expected to present poor flowability.

The ethanol plant produced DDGS at the two moisture levels and placed it in separate stockpiles in their warehouse.

About 5,000 lb. of DDGS was augered into a portable, on-farm grinder mixer, bypassing the grinding hammers, and the appropriate flowability agent was added. The mixer was equipped with a single vertical screw in the mixing hopper and an electronic scale for weighing mixer contents. Treated lots of DDGS were weighed and loaded into one of eight individual compartments in an auger-equipped feed truck.

Researchers simulated the transport of DDGS that often occurs in the commercial feed industry by sending the truck on a 300-mile trip over a weekend. Bumps in the road and vibrations during travel, along with cooling of the DDGS, all increase the chance that the DDGS will bridge and not flow freely. The same truck and operator were used on four different days to complete the experiment.

Researchers found flow rate was clearly poorer for DDGS with 12% moisture, compared with 9% moisture DDGS (Figure 1).

Similarly, the subjective flowability score was significantly higher for the wetter DDGS, illustrated in Figure 2. This indicates it was more difficult for the operator to unload compartments containing DDGS with 12% moisture, compared with those containing the drier DDGS.

None of the flowability agents significantly altered DDGS flow rate compared to the control treatment, which used no flowability agents (Figure 3). While there were numerical flow rate differences for various treatments, the researchers concluded these differences were not consistent enough to expect them to occur routinely.

The flow rate of DDGS treated with DMX-7 was significantly lower than that of the zeolite-treated DDGS, but neither of these was different than the additive-free control group.

Similar to the flow rate, subjective flow score was not consistently changed by the addition of the flowability agents tested in this research study (Figure 4).

The Minnesota researchers note this is the first attempt to test additives for improving flow rate of DDGS. They speculate that different inclusion rates or altogether different flowability agents should be tested. Their research work will continue to investigate what characteristics of DDGS will help predict flowability problems under commercial conditions.

Researchers: Lee Johnston, University of Minnesota, Morris, MN; Jerry Shurson, University of Minnesota, St. Paul, MN; John Goihl, Agri-Nutrition Services, Inc., Shakopee, MN. Contact Johnston by phone (320) 589-1711.

Proper Amino Acid Ratios Cut Costs, Nitrogen Excretion

Determining proper amino acid ratios in growing pigs' diets limits feed expense and reduces nitrogen excretion, according to a research report from the University of Kentucky.

If the required ratio is set too low, performance will be limited due to inadequate levels of amino acids in the diet. In contrast, if the required ratio is set too high, excess supplementation will occur, increasing cost and nitrogen excretion, says lead researcher Merlin Lindemann.

Lysine is the most limiting amino acid in most swine diets. Once that level is established, it is fairly easy to determine and fill other amino acid needs if the ratio to lysine is known. Researchers disagree about the proper ratio of tryptophan to lysine, however.

Another confounding factor is whether the ratio applies to total dietary amino acids, because not all dietary proteins are digested equally, nor are all amino acids absorbed equally. Therefore, a ratio at the muscle level, where the majority of protein synthesis occurs, may not be the same as the ratio for total dietary amino acids.

To find out the applicable ratio for amino acid absorption, University of Kentucky scientists studied the required standard ileal digestible trytophan:lysine (SID Trp:Lys) ratio for growing pigs fed mainly a corn-soybean meal diet.

A total of 120 crossbred pigs averaging 57 lb. were placed on five separate diets and housed five pigs/pen. The dietary lysine level was set at 0.75% total lysine, which equated to a standard ileal digestible (SID) lysine level of 0.66% based on the ingredients that were used. The dietary treatments were increasing SID Trp:Lys ratios (from 12.43 to 18.42%) fed for 21 days.

Determination of the required ratios was based on growth performance (average daily gain) and plasma urea nitrogen (PUN), which is reduced when the proper ratio is attained.

Analysis of the data confirmed that proper responses were achieved for an optimum Trp:Lys ratio of 15.70 (Figure 1) for average daily gain and a plasma urea nitrogen of 15.64 (Figure 2). This produced a mean ratio of 15.67, based on the true (or standardized) ileal trytophan and lysine values.

When converted to a total dietary Trp/Lys ratio for the feed ingredients tested, the ratio becomes 17.0.

In sum, this study provides very clear agreement between the response measures for the SID Trp:Lys ratio for growing pigs fed mainly corn-soybean diets.

Researchers: Merlin Lindemann, Anthony Quant and Gary Cromwell, all of the University of Kentucky. Contact Lindemann by phone (859) 257-7524, fax (859) 323-1027 or e-mail merlin.lindemann@uky.edu.

Ractopamine Improves Growth, Carcass Value

When finishing pigs were fed a control diet vs. ractopamine-supplemented (Paylean from Elanco Animal Health) diet for 27 days prior to slaughter, ractopamine improved growth and feed conversion, decreased backfat and improved loin thickness.

Paylean is a feed additive that was recently approved for use in Canada. The active ingredient of Paylean is ractopamine, a beta-adrenergic agonist known to stimulate muscle growth and slow fat deposition.

In the study performed at the Prairie Swine Centre in Saskatoon, Saskatchewan, 530 animals were assigned to either a control diet or a diet supplemented with Paylean to supply 5 mg/kg or 5 ppm ractopamine.

Ractopamine improved average daily gain 12.9%, feed conversion 12.5%, decreased backfat 0.04 in. (1 mm) and improved loin thickness 0.1 in. (2.5 mm).

Paylean-fed pigs were fed a diet similar to the barn's normal gilt finisher, except lysine was increased to 1% and the ractopamine was added.

Table 1 shows the performance and carcass parameters and the feed costs associated with the use of ractopamine.

The feed additive cut age at marketing by about one week, and also reduced the number of tail-enders from 7.5% to 0.5%.

Assuming pig flow can accommodate filling the room or barn one week earlier, the net return/pig place would increase by about $5/year. The drop in the number of tail-enders would increase gross revenue by $2.17/hog under normal market conditions.

While the benefit of using ractopamine will depend on individual farm circumstances, typical farms should expect a net return of $2-3/pig sold.

Researchers: J.F. Patience, A.D. Beaulieu, J. Merrill, D.A. Gillis and G. Vessie, all of the Prairie Swine Centre. Contact Ken Engele, assistant manager, Information Services, by phone (306) 373-9922, fax (306) 955-2510 or e-mail Ken.Engele@usask.ca.

Table 1. The Effect of 5 ppm Ractopamine (RAC) on Parameters Influencing the Economics of Pork Production
Parameter Control RAC
Days on test 30.1 26.5
Tail-enders 20 2
No. of pigs condemned 0 2
No. of pigs DOA* 0 3
Overall ADG, lb./day* 2.40 2.70
Overall FCE* 0.32 0.36
lb. feed/pig started 222.0 196.2
Backfat, in. 0.72 0.68
Loin thickness, in. 2.73 2.83
Carcass index 109.96 110.57
Carcass premium, $ 1.64 1.34
Carcass value, $ 118.77 119.08
Feed cost ($/pig)
Basal cost 13.73 12.19
Extra amino acids 0.00 0.59
Extra minerals and vitamins 0.00 0.21
Ractopamine 0.00 1.72
Total feed cost, $ 13.73 14.71
*DOA=Dead on arrival; ADG=Average daily gain;
FCE= Feed conversion efficiency

Adding Glycerol Improves Pelleting, Provides Nursery Growth Alternative

A Kansas State University (KSU) research team recently investigated whether glycerol, a byproduct of the biofuels industry, could decrease diet cost by replacing corn as an energy source. They also looked at whether adding glycerol to a corn-soybean meal diet prior to pelleting could help reduce wear and tear on pelleting machines.

Crude glycerol is the primary co-product of the biodiesel production process. If U.S. biodiesel production facilities continue to multiply as predicted, biodiesel production capacity will soon exceed 2.5 billion gal. This level of production will yield nearly 1.3 million tons of glycerol.

Part of the glycerol is currently processed into an industrial chemical. However, the industrial glycerol market is already saturated. Interest has been growing in utilizing crude glycerol as a livestock feed ingredient to reduce diet costs. But little has been known about glycerol's nutritional value, or how it might impact feed quality and feed processing efficiency.

A series of KSU experiments looked at the effect glycerol might have on pellet mill production efficiency.

Three experimental diets were manufactured and pelleted, and data was collected at the KSU Grain Science Feedmill. All of the diets were steam- conditioned and pelleted at specific temperatures, using a pellet mill equipped with a 4 × 32 mm pellet die.

The six treatments in the first experiment were made up of a corn-soybean meal-based swine grower diet, formulated to contain 0, 3, 6, 9, 12 and 15% crude glycerol.

Experiment two included seven treatments: a control diet with no added soy oil or glycerol; the control diet with 3% or 6% added soy oil; the control diet with 3% or 6% added glycerol; or the control diet with 6% or 12% of a 50:50 soy oil-to-glycerol blend. Experiment three included five treatments: a control with no added lactose or glycerol; the control diet with 3.6 or 7.2% lactose; or 3.6 or 7.2% glycerol.

Each experimental diet was replicated by manufacturing a new batch of feed three times. Pellet mill electrical consumption, production rate, hot pellet temperature, motor load, feeder rate, conditioning rate and pellet durability were measured.

The researchers concluded the glycerol improved pellet quality in all three experiments. The addition of glycerol should increase the production efficiency of the pelleting process and decrease energy cost for the pellet mill. The data indicate glycerol can be added to a diet with soy oil in a blend to improve pellet production efficiency and pellet quality, compared to a diet containing only soy oil. Specific information about how each dietary formulation performed during the pelleting process is contained in Tables 1, 2 and 3.

Using the diets from the second experiment, the researchers also evaluated the effects of glycerol, soy oil and a 50:50 soy oil/glycerol blend on nursery pig performance.

The seven dietary treatments were corn-soybean meal-based control diet with no added soy oil or glycerol; the control diet with 3% or 6% added soy oil; 3% or 6% added glycerol; and 6% or 12% additions of a 50:50 soy oil/glycerol blend.

The diets were fed to 182 pigs in a 26-day growth period. Pigs weighed around 23 lb. at the beginning of the trial, and were randomly allotted to treatment, with between five and six pigs/pen, and five pens/treatment.

The results indicated glycerol can be included in a diet up to 6%, either alone or in combination with soy oil without affecting final body weight in pelleted phase 2 nursery diets. Pigs fed increasing levels of glycerol had increased average daily feed intake (ADFI). Feed:gain increased with increasing soy oil or the soy oil/glycerol blend, resulting in similar average daily gain between pigs fed soy oil, glycerol or the 50:50 soy oil/glycerol blend.

Adding glycerol to the diet did not influence feed:gain compared to the control. Results of the feeding trials are shown in Table 4.

Glycerol could be added in place of corn in some swine diets to decrease diet cost, according to the researchers. Glycerol's benefits during the pelleting process can also help lead to energy savings for the production mill.

Researchers: Crystal N. Groesbeck; Leland. J. McKinney; Joel M. DeRouchey; Mike D. Tokach; Robert D. Goodband; Jim L. Nelssen; Steve S. Dritz, DVM; Allen W. Duttlinger; and Keith C. Behnke, Kansas State University. Contact Groesbeck at 785-532-1270 or email cgroesbe@ksu.edu.

Table 1. Effects of Added Glycerol on Pellet Production Efficiency, Exp. 1ab
Added Glycerol, %
Item 0 3 6 9 12 15
Conditioning temperature, °F 149.7 150.0 150.2 150.2 149.8 149.8
Hot pellet temperature, °F 169.1 167.8 166.1 169.9 161.9 163.0
Delta temperature, °F 18.9 17.3 15.5 19.2 11.7 12.6
Voltage, volts 250.4 250.0 248.9 252.3 250.1 250.3
Amperage, amps 29.3 25.2 23.6 22.9 19.5 18.1
Motor load, % 54.7 45.7 41.7 41.0 33.3 30.3
Pellet durability index
Standard, % 90.1 92.1 93.5 95.7 94.9 94.7
Modified, % 87.5 89.4 91.2 93.9 92.3 91.6
Production rate, tons/hour 1.32 1.27 1.24 1.11 1.09 1.10
Total energy, kilowatt hour/ton 7.62 6.81 6.51 7.09 6.10 5.60
aAll diets were corn-soybean meal-based swine grower diets.
bEach experimental diet was replicated by manufacturing a new batch of feed three times.
Table 2. Effects of Added Glycerol on Pellet Production Efficiency, Exp. 2ab
Soy Oil Glycerol Blendc
Item Control 3% 6% 3% 6% 6% 12%
Conditioning temp., °F 150.4 151.3 150.6 151.3 150.5 151.1 150.4
Hot pellet temp., °F 171.1 165.5 161.0 165.4 164.1 159.9 156.7
Delta temp., °F 20.2 13.9 10.0 13.7 13.2 8.4 5.9
Voltage, volts 247.7 249.9 245.8 248.4 250.1 249.4 249.3
Amperage, amps 28.3 23.0 19.6 23.7 22.8 20.9 16.0
Motor load, % 53.6 45.9 34.6 42.9 41.6 36.3 26.9
Pellet durability index
Standard, % 92.6 81.6 58.3 94.7 95.5 85.4 80.3
Modified, % 89.9 74.7 40.0 91.9 92.2 78.3 65.8
Production rate, tons/hour 1.38 1.42 1.40 1.35 1.38 1.40 1.36
Total energy, kilowatt hour/ton 7.58 6.09 5.16 6.50 6.18 5.45 4.44
aAll diets were formulated to the same lysine to metabolizable energy ratio.
bEach experimental diet was replicated by manufacturing a new batch of feed three times; each run consisted of 750-lb. batches.
cAddition of 50% soy oil and 50% glycerol.
Table 3. Effects of Added Glycerol on Pellet Production Efficiency, Exp. 3a
Lactose Glycerol
Item Control 3.6% 7.2% 3.6% 7.2%
Conditioning temperature, °F 150.3 150.2 150.3 149.7 150.3
Hot pellet temperature, °F 166.9 168.3 171.3 164.5 158.3
Delta temperature, °F 16.5 18.2 20.9 14.7 8.0
Voltage, volts 252.2 251.9 248.0 251.7 252.3
Amperage, amps 21.6 22.2 23.0 19.3 17.2
Motor Load, % 33.8 37.1 38.4 30.1 27.1
Pellet durability index
Standard, % 86.1 88.5 90.1 89.9 91.8
Modified, % 87.0 89.2 90.8 89.8 92.0
Production rate, tons/hour 0.98 1.03 1.02 0.99 0.97
Total energy, kilowatt hour/ton 8.10 8.00 8.20 7.20 6.60
aEach experimental diet was replicated by manufacturing a new batch of feed three times;
each run consisted of 750-lb. batches.
Table 4. Effects of Glycerol on Pellet Mill Production and Nursery Pig Performance
Soy oil, % Glycerol, % Blend, %
Item Control 3 6 3 6 6 12
Pellet mill data
Amperage, amps 28.2 23.0 19.6 23.7 22.8 20.9 16.0
Motor load, % 53.6 45.9 34.6 42.9 41.6 36.2 26.9
Production efficiency, kilowatt hour/ton 7.8 6.1 5.2 6.5 6.2 5.5 4.3
Pellet durability index, % 93.0 81.6 58.3 94.7 95.5 85.4 80.3
Day 0 to 26
Average daily gain, lb. 1.17 1.26 1.22 1.25 1.26 1.22 1.25
Average daily feed intake, lb. 1.73 1.73 1.68 1.79 1.80 1.67 1.68
Feed/gain 0.68 0.73 0.73 0.70 0.70 0.73 0.74
Final weight, lb. 54.34 56.76 55.88 56.76 56.76 55.88 56.54

Selenium Source Matters in Sow Diets

Organic selenium is showing superior results to inorganic selenium, reproductively, and especially in enhancing the selenium status of newborn and weanling pigs.

In research at Ohio State University, feeding organic selenium not only increased milk selenium content, but the resulting milk selenium also maintained a more constant level over several parities, offering progeny an advantage in survival and growth once weaned.

Selenium deficiency in high-producing sows still raises concerns in some regions, as does sudden postweaning deaths, which have been attributed to inadequate selenium.

Sodium selenite, or inorganic selenium, was approved at a supplemental level of 0.3 ppm in the early 1980s by the Food and Drug Administration (FDA). It is routinely added to most sow rations, and has reduced problems of deficiency, but problems persist in sows and pigs.

Organic selenium differs from the inorganic form in that the selenium is incorporated into a new amino acid form called selenomethionine; the product has been approved by the FDA.

Both forms of selenium provide enhancements to the sow and piglets, but research findings of the last few years suggest organic selenium adds 0.3 additional pigs/litter vs. inorganic selenium, improves sow health and reduces stillbirths.

However, its biggest benefit resides in its ability to more effectively transfer organic selenium to the developing fetus, resulting in greater selenium reserves in the newborn pig.

Figure 1 demonstrates that when levels of 0, 0.15 and 0.30 ppm selenium were fed to sows from both sources of the supplement, the newborn pig had greater body selenium contents when the sow was fed organic selenium.

The “C” mark on Figure 1 reflects a sow dietary treatment when a 50-50 blend of inorganic to organic selenium was fed. Results indicated there was no advantage to feeding 100% organic selenium vs. the combination of the two selenium sources.

Organic selenium not only is transferred more effectively to the developing fetus, it is also effectively transferred to the milk of lactating sows.

In the four-parity study, Figure 2 shows that when females were fed a non-selenium-supplemented diet, milk selenium concentration was highest in young gilts and declined with ensuing parities, reflecting the loss of body selenium over time.

When inorganic selenium was fed, there was a small boost in milk selenium from the base 0.15 ppm to 0.3 ppm, but still a decline in milk selenium with later parities. In contrast, when organic selenium was fed, milk selenium levels were higher and remained relatively constant throughout the four parities.

This research suggests that the addition of organic selenium is clearly more beneficial to both gestating and lactating sows, and in enhancing the selenium status of pigs at weaning.

Researcher: Don Mahan, Ohio State University. Contact Mahan by phone (614) 292-6987, fax (614) 292-7116 or e-mail mahan.3@osu.edu.