Feeding Frequency Has Limited Impact On Group-Housed Sows

Kansas State University (KSU) researchers recently concluded that increasing the number of daily feedings did not dramatically impact the performance or welfare of group-housed sows and gilts in gestation.

The National Pork Board-sponsored research project investigated ways to deal with the “boss sow” syndrome that occurs when gestating sows and gilts are housed in groups. Dominant sows consume more feed than desired, often at the expense of other sows in the group.

The KSU research team increased the feeding frequency from two to six times/day and spaced the feedings in an attempt to satisfy the boss sows. Researchers theorized that a more satisfied boss sow would reduce the variation in sow weight gain and injury among penmates.

The experiment included 496 group-housed gilts and sows on a commercial sow farm in northeastern Kansas.

In the study, 208 sows averaging three parities were randomly allotted to treatments consisting of 13 pens/treatment. After weaning, sows were moved to a breeding facility for boar exposure and were housed in crates until estrus was detected.

Sows were inseminated twice. The day after the second service, 24 to 40 sows were randomly allotted by parity, and assigned in groups of eight to 16 × 10-ft. pens. Sows were weighed and backfat was measured at the last rib, 2.5 in. off the midline (P2 position) when allotted to their group, then again as they entered the farrowing house.

Included in the study, 288 replacement gilts were brought to a breeding facility and housed in groups with boar exposure until estrus detection. Gilts were inseminated twice and moved to 16 × 10-ft. pens, with 12 gilts/pen.

Gilts were housed in this facility until Day 42 of gestation, when gilts of similar breeding dates and treatment were combined and moved to another facility with larger pens until farrowing. The 12 replicates/treatment were combined to give six replicates/treatment after Day 42 of gestation. Gilts were weighed and backfat measured at the P2 position at Day-42 allotment and again before farrowing.

All gilts and sows received a grain sorghum-soybean meal gestation diet. Feed drops were set to provide 5.5 lb. of feed/sow/day and 4.5 lb./gilt/day. All feed was dropped onto solid concrete floors.

Feed drops were scheduled twice daily, at 7:00 a.m. and 3:30 p.m., for specific groups. Other groups received six feed drops/day at 7:00 a.m., 7:30 a.m., 8:00 a.m., 3:30 p.m., 4:00 p.m. and 4:30 p.m. Feed drops were set at the beginning of the trial. Adjustments were made if a sow or gilt was removed from the trial.

To accommodate the amount of daily feed needed, sow pens had two feed drops. Gilt pens had three feed drops from Days 0 to 42 and five feed drops/pen from Day 42 to farrowing. An Accu-Drop Feed Dispenser by Automated Production (AP) Systems was used.

Sow and gilt aggressiveness was determined by visually scoring lesions on the total body and vulva. Total body lesions were scored as follows:

#1 — No blemishes to some reddening or calluses;

#2 — Less than 10 scrapes or five small cuts;

#3 — More than 10 scratches or five small cuts;

#4 — Most or the whole area was covered with scratches/wounds with little or no untouched skin.

Similarly, visual scoring of the vulva included:

#1 — No obvious wounds;

#2 — Slight lacerations;

#3 — Severe lacerations observed; and

#4 — A female with severe lacerations and portions of the vulva absent.

Structural integrity for sows and gilts was performed by visual scoring of feet and legs on a similar scoring system ranging from 1 (no lameness in front or rear legs) to 3 (severe structural problems and inability to get up or walk).

Hoof integrity scores were also observed. Lesion scores were recorded before mixing on Day 1, and every 14 days until farrowing.

Vocalization was recorded using an Extech Model 407764 data logging sound level meter. The sound meters were placed near the feed drop and above the feeding area. A directional cone was attached to the microphone to decrease extraneous noise from adjacent pens. Vocalization was not measured in gilts due to the combining of pens and movement to another facility on Day 42.

Researchers found the vocalization was greater in the two-hour period around the morning and afternoon feeding periods for sows fed six times/day vs. sows fed twice daily. As Figures 1 and 2 on page 30 show, vocalization increased with each feeding and returned to baseline values.

Sows fed six times/day had three distinct vocalization peaks during each feeding period, indicating they were more active over the feeding period. Increased vocalizations were interpreted as a negative response.

The researchers concluded feeding frequency did not influence total sow removal or the proportion of sows removed for reproductive failure. Although relatively few sows were removed for structural problems, those that were removed were on the twice/day feeding frequency.

Gilts experienced no influence of feeding frequency on removal from the trial because of reproductive failure or structural problems.

Increasing feeding frequency from two to six times/day had no effect on overall gain, average daily gain and backfat change in the sow group.

Increasing the feeding frequency for the gilts did not affect weight gain from Days 0 to 42 of gestation; however, there was a trend for gilts fed six times/day to have a greater average daily gain. Therefore, gilts gained more weight from Days 0 to 42 compared to gilts fed twice/day. There were no differences in weight gain from Day 42 of gestation until farrowing. Thus, final weight was similar for the two feeding frequencies.

Among sows or gilts there were no differences in number born alive, stillbirths or mummies.

Sow aggressiveness was more pronounced, as determined by visual scores of skin and vulva lesions, when fed twice/day as compared to the sows fed six times/day. Gestating sows fed six times/day experienced less structural problems with feet, legs and hoofs. The researchers noted all scores were low, indicating relatively few structural or aggression problems.

Gilts demonstrated no differences for skin or vulva lesions, or leg and hoof scores during the research period.

The researchers concluded increasing the feeding frequency from two to six times/day does not have a dramatic impact on performance or welfare of group-housed gilts and sows.

Researchers: Jason Schneider; Mike Tokach; Steven Dritz, DVM; Robert Goodband; Jim Nelssen; Joel DeRouchey; Kansas State University. Contact Goodband at (785) 532-1228.

Virginiamycin Improves Phosphorus Utilization In Grow-Finish Pigs

University of Kentucky (UK) researchers recently conducted five experiments to determine if the antibiotic virginiamycin (Stafac) would impact phosphorus utilization in growing-finishing pigs, thus reducing phosphorus excretion in manure.

The feeding of low doses of antibiotics as growth promoters has been a common practice for over half a century. Although the mode of action of antibiotics on growth is primarily attributed to their effects on animal health, they have also been shown to have a positive effect on energy and nitrogen utilization in swine and other animals. Whether antibiotics have an effect on mineral utilization is not known, but some poultry research suggests certain antibiotics may benefit phosphorus utilization.

The first four experiments were conducted with 70 crossbred barrows housed in metabolism crates. The pigs, 115 to 140 lb., were fed at 3% of their body weight, representing 85-90% of ad libitum intake.

Control pigs were fed a basal diet consisting of corn and soybean meal fortified with minerals and vitamins, but no supplemental phosphorus. A second treatment included the basal diet with 10 grams of virginiamycin per ton of feed. All of the phosphorus in the diets was supplied by the corn and soybean meal, thus most of the phosphorus in the diets were in the form of phytate, an organic form of phosphorus that is poorly available to pigs. Five-day balance experiments were conducted with complete, but separate, collection of feces and urine.

Table 1 shows the combined results of the four experiments. The addition of virginiamycin improved phosphorus digestibility. Even though pigs fed virginiamycin consumed more phosphorus, 7.20 g./day vs. 7.01 g./day, the antibiotic resulted in a 5-6% reduction in the amount of phosphorus excreted (4.57 g./day vs. 4.83 g./day).

Phosphorus excretion, expressed as a percent of intake, was reduced from 69% in control pigs to 63% in those fed the antibiotic. This means if the two groups of pigs had consumed the same amount of feed, the reduction in phosphorus excretion would have been approximately 9% in the virginiamycin-fed pigs compared with the controls.

A fifth experiment was conducted in an attempt to explain the reason for the improvement in phosphorus utilization in the virginiamycin-fed pigs.

In this study, 32 crossbred pigs, averaging 64 lb., were fed corn-soy diets with and without virginiamycin at 10 g./ton for 16 weeks to market weight. Samples were taken from the small intestine (ileum) after slaughtering the pigs to assess the bacterial profile. The most interesting effect of virginiamycin was an eight-fold increase in the number of phytate-utilizing bacteria in the gut of pigs fed the antibiotic.

The results suggest that the improvement in phosphorus utilization from the feeding of virginiamycin is related to a change in the bacterial profile in the small intestine, including a marked increase in the number of phytate-utilizing microorganisms.

The inclusion of virginiamycin in growing-finishing diets is an additional tool that can be used to improve phosphorus utilization, thus reducing phosphorus excretion in swine manure.

Researchers: Merlin D. Lindemann, Jorge H. Agudelo, Gary L. Cromwell and Melissa C. Newman, University of Kentucky, Lexington. Contact Lindemann at (859) 257-7527.

Flow Agent Could Skew Particle Size Tests

Feed particle size may be underestimated in some laboratory particle size analysis procedures — depending on whether a flow agent is used during the analysis, say Kansas State University and Midwest Laboratory researchers.

According to the American Society of Biological and Agricultural Engineers' standards, particle size analysis can be conducted with or without the use of a flow agent, such as synthetic amorphous precipitated silica. When a flow agent is added to ground grain, it helps move particles through screens. However, when the same analysis procedures are used without a flow agent, different results occur.

After conducting thorough experimental analyses, the researchers say particle size analysis conducted with a flow agent can result in a mean particle size that is approximately 80 microns smaller than analysis conducted without a flow agent.

The standard experimental protocol allows for particle size analysis with or without the use of a flow agent, explains Robert Goodband, KSU swine nutritionist; therefore it is very important that producers ask whether a flow agent was used.

“Particle size analysis costs about $10-15/sample,” Goodband explains. “For every 100 microns over the recommended 700 microns of particle size (analyzed without a flow agent), a producer will lose approximately $0.50/pig.”

For example, a 1,000-micron particle size diet will cost a producer $1.50 in poorer feed/gain. If a flow agent is used in particle size analysis without the producer's knowledge, the actual particle size may be underestimated, and the producer ends up thinking the feed is ground finer than it is.

The researchers conducted a retrospective analysis on 603 samples of ground corn analyzed for particle size at a commercial laboratory. The results of the testing were entered into a spreadsheet that calculated the mean particle size and its standard deviation. A second sample was then mixed with 0.5 g. of synthetic amorphous precipitated silica, and the procedure was repeated. Results of both analyses were compared with a “method of agreement” analysis, a statistical procedure used to compare results of two different analytical procedures.

A comparison was made between samples analyzed with a flow agent, as shown in the “X” axis of Figure 1 on page 32, and without a flow agent, as shown on the “Y” axis.

If both methods were in perfect agreement, all values would land on the straight line running diagonally through the middle of the chart. If the values are consistently distributed on either side of the perfect agreement line, this would indicate that one of the procedures is biased, or consistently different than the other. In this case, all the samples are above this line, indicating there is a bias, and that using a flow agent will result in a particle size value smaller than no flow agent.

Figure 2 on page 32 illustrates the next procedure used to test whether the bias was consistent across different particle sizes. The results indicate the analysis with a flow agent will consistently be 80 microns less than the analysis without using a flow agent.

For example, if the same sample is split and sent to two labs, one using a flow agent and the other not, the value from the lab using the flow agent is 620 microns vs. 700 microns for the lab not using a flow agent.

Figure 3 illustrates a comparison of the particle size standard deviation conducted with or without a flow agent. The figure shows that using a flow agent will produce a greater standard deviation value than without a flow agent. The diagonal line through the center of the chart would represent a perfect comparison between the two procedures.

The researchers believe all existing data reporting the effects of particle size and its standard deviation on growth performance and diet flowability have been conducted without the use of a flow agent. Thus, use of a flow agent in analysis would require some type of conversion when interpreting or comparing results. Because the results between the two procedures differ, the researchers believe the official standards need to be clarified.

Researchers: Robert Goodband; Steven Dritz, DVM; Mike Tokach; Joel DeRouchey; and James Nelssen, Kansas State University; and William Diederich, Midwest Laboratories, Omaha, NE. Contact Goodband at (785) 532-1228.

Effects of DDGS On Grow-Finish Performance

Dried distiller's grains with solubles (DDGS) can lead to reduced average daily gain (ADG) and reduced average daily feed intake (ADFI) in grow-finish diets when included at levels grater than 15%, according to Kansas State University (KSU) researchers.

Pork producers need to take a hard look at the tradeoff between the levels, source and quality of DDGS used, as well as the economics involving both feed cost and daily gain, before using the by-products of ethanol production in rations.

KSU researchers conducted three separate experiments to test increasing levels of the same source of DDGS in grow-finish diets. Trials were completed over four years at the same commercial facility.

The first study involved 1,050 pigs in a 28-day study in May 2002. Pigs went on test weighing 104.9 lb. and were fed one of six dietary treatments.

There were seven pens/treatment with 24 to 26 pigs/pen. Experimental diets were corn-soybean meal-based fed in meal form. Diets contained either 0 or 15% DDGS with 0, 3 or 6% added fat.

Overall, there were no interactions between DDGS and fat level. ADG and feed/gain improvements were noted as added fat increased; no difference in growth performance was seen between pigs fed 0 or 15% DDGS (Table 1).

The second experiment included 1,038 pigs with an average initial weight of 102.1 lb. The 56-day study began in August 2005. Pigs were fed diets with either 0, 10, 20 or 30% DDGS from the same ethanol plant as in the first experiment.

Pigs were randomly allotted to one of four dietary treatments with 10 replications/treatment. Each pen contained 24-26 pigs. All diets contained 6% added fat and were fed in meal form. Dietary treatments were fed in two phases, with phase 1 from Days 0 to 28, and phase 2 from Days 28 to 56.

The phase 1 and phase 2 diets were formulated to 0.95 and 0.78% true ileal digestible (TID) lysine, respectively. The energy value used for both corn and DDGS was 1.551 kcal/lb. of metabolizable energy (ME). The diet containing 30% DDGS did not need supplemental phosphorus.

Overall, there was a trend for decreased ADG and ADFI as DDGS increased. The greatest reduction occurred in pigs fed greater than 10% DDGS (Table 2).

The third experiment, a 56-day study to evaluate the effects of DDGS on growth performance, included 1,112 pigs with an initial body weight of 110.4 lb. Pigs were randomly allotted to one of five dietary treatments, with nine pens/treatment and 25-28 pigs/pen.

Corn-soybean meal-based experimental diets, fed in meal form, contained 0, 5, 10, 15 or 20% DDGS with 6% added fat. Dietary treatments were fed in three phases. Phase 1 was fed from 0 to 130 lb., phase 2 from 130 to 180 lb., and phase 3 from 180 to 230 lb. Diets were formulated on a TID amino acid basis with 0.98, 0.83 and 0.73% TID lysine for phases 1, 2 and 3, respectively. The energy value used for both corn and DDGS was 1.551 kcal/lb. of ME.

Pigs fed 20% DDGS had reduced ADG compared to pigs fed either 0 or 10% DDGS (Table 3). Pigs had decreased ADFI with increasing levels of DDGS in the diet. Dietary levels of DDGS above 15% of the diet reduced growth performance in this experiment.

Researchers concluded added fat can be used with confidence to improve growth performance. Producers need to be aware of potential reductions in performance when feeding DDGS, regardless of inclusion level. While considering if DDGS is economical to lower diet cost, producers must accurately monitor close-out information to determine if growth performance is influenced. If growth is reduced, producers need to value DDGS on a margin-over-feed cost basis to account for a reduction in revenue from reduced market weight.

Researchers: Sara Linneen; Mike Tokach; Joel DeRouchey; Steven Dritz, DVM; Robert Goodband; James Nelssen; R.O. Gottlob; and R.G. Main, Kansas State University. Contact DeRouchey at (785) 532-2280.

Table 1. Effects of Virginiamycin on Phosphorus Digested, Retained, and Excreted by Growing-Finishing Pigs
Control Virginiamycin (10 g./ton)
Phosphorus intake, g./day 7.01 7.20
Phosphorus digested, g./day 2.29 2.72
Phosphorus retained, g./day 2.18 2.63
Phosphorus excreted, g./day 4.83 4.57
Phosphorus excreted, % of intake 69 63
Phytate-utilizing bacteria in small intestine, CFU/mg.1 22,400 182,000
1CFU = colony forming units in the ileal digesta.
Table 1. Effects of DDGS with Added Fat on Finishing Pig Performance (Exp. 1)a
Without DDGS With DDGS
Item Added fat, %: 0 3 6 0 3 6
Day 0 to 28
Average Daily Gain (ADG), lb. 1.98 2.12 2.12 2.02 2.03 2.17
Average Daily Feed Intake (ADFI), lb. 4.68 4.76 4.68 4.79 4.66 4.72
Feed/gain (F/G) 2.37 2.25 2.21 2.38 2.30 2.18
aA total of 1,050 pigs (initially 104.9 lb.) were used in this study with 7 replications per treatment.
Table 2. Effects of Increasing Levels of DDGS on Grower Pig Performance (Exp. 2)a
DDGS, %
Item 0 10 20 30
Day 0 to 56
ADG, lb. 1.87 1.89 1.83 1.84
ADFI, lb. 4.28 4.35 4.21 4.18
F/G 2.29 2.30 2.29 2.28
Total Removals 3 10 9 8
aA total of 1,038 pigs (initially 102.1 lb.) were used in this study with 10 replications per treatment.
Table 3. Effects of Increasing Levels of DDGS on Pig Performancea
DDGS, %
Item 0 5 10 15 20
Day 0 to 56
ADG, lb. 2.11b 2.08bc 2.10b 2.07bc 2.01c
ADFI, lb. 5.11b 4.93bc 5.02bc 4.90c 4.85c
F/G 2.42b 2.37c 2.38bc 2.37c 2.41b
aA total of 1,112 pigs (initially 110.4 lb.) with 25 to 28 pigs/pen using 45 pens provided 9 replications/treatment.
bcdMeans within a row with different superscripts differ (P < 0.05).