The effects of immunocastration and dried distillers grains with The effects of immunocastration and dried distillers grains with solubles withdrawal on growth performance, carcass solubles withdrawal on growth performance, carcass characteristics, fatty acid analysis, and iodine value of pork fat characteristics, fatty acid analysis, and iodine value of pork fat depots depots

Summary A total of 1,360 pigs (PIC 337 × 1050, initially 53.0 lb) were used in a 125-d study to determine the effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration (IC; Improvest, Pfizer Animal Health, Kalamazoo, MI) on growth performance and carcass fat quality of growing-finishing pigs. Pens of pigs were randomly allotted by initial weight and gender (barrows or IC) to 1 of 3 dietary treatments with 8 replications per treatment for a total of 48 pens with 27 to 29 pigs per pen. Treatments were arranged in a 2 × 3 factorial with the main effects of gender (barrow or IC) and diet (0% DDGS throughout, 30% DDGS throughout, or 30% DDGS through d 75 then withdrawn to 0% to d 125). Boars were injected with Improvest on d 39 and 74 of the study. Dietary treatments were corn-soybean meal– based diets and fed in 5 phases. No gender × diet interactions ( P > 0.18) were observed except for a tendency for F/G ( P < 0.07) during the second phase (d 25 to 53), when 1 of the 2 barrow groups fed 30% DDGS had an increase in ADFI resulting in poorer F/G. For the entire period before the second Improvest injection (d 0 to 74), barrows tended ( P < 0.08) to have increased ADG (1.98 vs. 1.95 lb) and increased ( P < 0.001) ADFI (4.32 vs. 3.91 lb) but were less efficient ( P < 0.001) than boars (2.19 vs. 2.01). During the same time period, pigs fed 30% DDGS had reduced ( P


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The Effects of Immunocastration and Dried Distillers Grains with Solubles Withdrawal on Growth Performance, Carcass Characteristics, Fatty Acid Analysis, and Iodine Value of Pork Fat Depots1 M. D. Asmus, M. D. Tokach, S. S. Dritz2 , J. L. Nelssen, R. D Goodband, and J. M. DeRouchey Summary A total of 1,360 pigs (PIC 337 × 1050, initially 53.0 lb) were used in a 125-d study to determine the effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration (IC; Improvest, Pfizer Animal Health, Kalamazoo, MI) on growth performance and carcass fat quality of growing-finishing pigs.Pens of pigs were randomly allotted by initial weight and gender (barrows or IC) to 1 of 3 dietary treatments with 8 replications per treatment for a total of 48 pens with 27 to 29 pigs per pen.Treatments were arranged in a 2 × 3 factorial with the main effects of gender (barrow or IC) and diet (0% DDGS throughout, 30% DDGS throughout, or 30% DDGS through d 75 then withdrawn to 0% to d 125).Boars were injected with Improvest on d 39 and 74 of the study.Dietary treatments were corn-soybean mealbased diets and fed in 5 phases.No gender × diet interactions (P > 0.18) were observed except for a tendency for F/G (P < 0.07) during the second phase (d 25 to 53), when 1 of the 2 barrow groups fed 30% DDGS had an increase in ADFI resulting in poorer F/G.For the entire period before the second Improvest injection (d 0 to 74), barrows tended (P < 0.08) to have increased ADG (1.98 vs. 1.95 lb) and increased (P < 0.001) ADFI (4.32 vs. 3.91 lb) but were less efficient (P < 0.001) than boars (2.19 vs. 2.01).During the same time period, pigs fed 30% DDGS had reduced (P < 0.002) ADG and poorer feed efficiency.
For the period after the second Improvest injection to the end of the trial (d 74 to 125; 51 d after the second dose), IC pigs had increased (P < 0.01) ADG (2.29 vs. 2.10),

Introduction
By-products such as dried distillers grains with solubles (DDGS) are often used as alternatives to corn and soybean meal in swine diets.Although these ingredients are used with the intent of lowering feed costs, they have been shown to negatively affect performance and carcass characteristics.One main area of concern is the reduction in carcass yield with pigs fed high-fiber diets as well as the negative effect of DDGS on fat quality.Soft carcass fat with a high iodine value (more unsaturated fat) has consistently been observed in pigs fed high levels of DDGS; however, removing DDGS as the source of unsaturated fat from the diet prior to harvest lowers carcass fat IV.
Improvest (Pfizer Animal Health, Kalamazoo, MI), an immunocastration technology, allows pigs to perform as boars until the second immunization injection.After the second immunization, IC pigs rapidly increase feed intake and growth rate.Our hypothesis was that pigs administered Improvest would deposit less fat prior to the second dose with a greater portion of their total fat deposition occurring late in the finishing stage; thus, we speculated that feeding high levels of unsaturated fat prior to

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the second dose would have less overall impact on IV with these pigs when less unsaturated fat is fed during the phase after the second dose.
Previous research has shown that reducing the level of DDGS in the diet before harvest has been successful in improving carcass yield and improving fat quality; however, no studies are available to determine the impact of the DDGS withdrawal strategy in combination with immunocastration.The objective of this trial was to determine the effects of withdrawing DDGS from the diets of barrows and immunocastrates prior to market on growth performance and carcass fat quality of growing-finishing pigs.

Procedures
The Kansas State University Institutional Animal Care and Use Committee approved the protocol used in this experiment.The study was conducted at a commercial research-finishing barn in southwestern Minnesota.The barns were naturally ventilated and double-curtain-sided. Pens had completely slatted flooring and deep pits for manure storage.Each pen was equipped with a 5-hole stainless steel dry self-feeder and a cup waterer for ad libitum access to feed and water.Daily feed additions to each pen were accomplished through a robotic feeding system (FeedPro; Feedlogic Corp., Willmar, MN) that delivered and recorded diets as specified.The equipment provided pigs with ad libitum access to feed and water.
A total of 1,360 pigs (PIC 1050 × 337, initially 53.0 lb) were used in a 125-d study.All pigs used in the study were individually tagged and tattooed at birth in sequential order; to minimize maternal effects, even numbers of pigs were used from each sow.To create gender differences, all odd-numbered pigs were left intact and even-numbered pigs were surgically castrated at 2 d of age per standard farm procedures.At weaning (~19 d of age), all pigs were transported to the commercial wean-to-finish barn and doublestocked in pens by gender (the other half of the barn was stocked with gilts).When pigs reached ~50 lb, all gilts were removed and pens were split by gender (barrow and boar) to single-stocking density.Pens of pigs (~28 barrows per pen or ~28 boars per pen) were randomly allotted by initial weight to 1 of 6 dietary treatments with 8 replications per treatment.Treatments were arranged in a 2 × 3 factorial with the main effects of gender (barrow vs. immunocastrate) and dietary DDGS duration (0% throughout, 30% throughout, or 30% from d 0 to 74 and no DDGS from d 74 to market).Dietary treatments were corn-soybean meal-based and fed in 5 phases (Tables 1 and 2).All diets were fed in meal form.On d 39 (~110 d of age), all boar pigs were administered a 2-ml primer dose of Improvest (Pfizer Animal Health, Kalamazoo, MI) in the high lateral aspect of the neck by a Pfizer Animal Health certified injection team (PAH), who also administered the second 2-ml dose on d 74 (~145 d of age).A PAH quality assurance check was performed on d 88 to ensure all pigs received both doses and did not exhibit any signs of typical boar behavior.Any pig thought to be a "suspect pig" (21 total) was re-dosed with an additional 2 ml of Improvest in the high lateral aspect of the neck, and the individual pig ID was recorded.
Pens of pigs were weighed and feed disappearance was recorded at d 0, 25, 53, 74, 87, 107, and 125 to determine ADG, ADFI, and F/G.On d 107 (180 d of age), all pigs were weighed individually and the 9 heaviest pigs per pen were selected (topped) and tattooed by pen to be transported to Natural Food Holdings (Sioux Center, IA).At

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that time, an additional 4 median weight pigs in each pen (4 pigs per pen, 32 pigs per treatment) were also identified to gain representative fat samples over time.These pigs were individually tattooed with a unique number (1 through 192), and 2 pigs per pen (16 per treatment) were transported with the 9 topped pigs to Natural Food Holdings for harvest.During harvest, the 2 selected median weight pigs were sequenced with a unique number corresponding to the tattoo given at the farm to allow for further tracking.The day after harvest, the left side of each carcass was transported by refrigerated truck to the University of Illinois Meat Sciences Laboratory (Urbana, IL) for full carcass breakdown.Standard carcass criteria of HCW and percentage carcass yield were collected on all pigs harvested.The other 2 median-weight pigs remained in their respective pens and were harvested on d 125, then transported to the University of Illinois Meat Sciences Laboratory for carcass processing.Fat samples were collected for both harvest dates from 4 fat depots (jowl, 10 th rib, clear plate, and belly) at the University of Illinois Meat Sciences Laboratory.These fat samples were then transported frozen to the K-State Analytical Lab (Manhattan, KS) for full fatty acid analyses.Percentage yield was calculated by dividing HCW at the plant by live weight at the plant.
Data were analyzed as a completely randomized design using the PROC MIXED procedure of SAS (SAS Institute, Inc., Cary, NC) with pen as the experimental unit.The main effects of gender and DDGS during withdrawal, as well as interactive effects, were tested.Differences between treatments were determined by using least squares means.Results were considered significant at P ≤ 0.05 and considered a trend at P ≤ 0.10.

Results and Discussion
No gender × diet interactions (P > 0.18) occurred with the exception of a tendency in F/G (P < 0.07) during the second phase (d 25 to 53), in which 1 of the 2 barrow groups fed 30% DDGS had an increase in ADFI resulting in poorer F/G.The other interaction tendency (P < 0.07) was for carcass yield on d 107, where there was a greater reduction in carcass yield for IC pigs compared with barrows when fed DDGS throughout than when fed the control diet throughout or when DDGS was withdrawn from the diet on d 74.Barrows had greater (P < 0.01) ADG (1.92 vs. 1.85) than boars from d 0 to 25 (Tables 3 and 4), which resulted in a tendency for barrows to have greater (P < 0.08) ADG than boars prior to the second Improvest immunization (d 74; Tables 5 and 6).Boars had decreased (P < 0.001) ADFI and improved (P < 0.001) F/G for all periods prior to the second immunization.Immediately after the second immunization (d 74 to 87), IC pigs continued to have lower (P < 0.001) ADFI, but grew faster (P < 0.03) than barrows, resulting in improved (P < 0.001) F/G.After this 2-wk period, feed intake increased rapidly in IC pigs such that they had greater (P < 0.001) ADFI for the last two phases of the trial (d 87 to 107 and d 107 to 125) than barrows.The higher feed intake allowed IC pigs to have much greater (P < 0.001) ADG during the last two phases than barrows.Feed efficiency also improved (P < 0.01) from d 87 to 107 for IC pigs but was similar to barrows from d 107 to 125.

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withdrawal or gender did not influence ADG or ADFI but did worsen (P < 0.001) feed efficiency.
Regardless of gender, pigs fed 30% DDGS had decreased (P < 0.02) ADG compared with pigs fed the control diet without DDGS from d 0 to 25, d 25 to 53, and for the entire period prior to the second Improvest immunization (d 74).Withdrawing DDGS from the diet on d 74 did not influence pig performance from d 74 to 107 but resulted in lower (P < 0.001) ADFI and improved (P < 0.001) F/G from d 107 to 125.The inclusion of 30% DDGS did not influence (P > 0.12) overall ADG or ADFI but worsened (P = 0.001) F/G regardless of withdrawal strategy.
Carcass yield was lower (P < 0.001) for IC pigs than barrows regardless of diet type or withdrawal strategy.Pigs fed the 30% DDGS diet throughout had decreased (P < 0.001) carcass yield; however, withdrawing DDGS from the diet on d 74 was effective at fully recovering the yield loss, returning yield to levels similar to that of the pigs fed the corn-soybean meal diet throughout.Final HCW were not influenced (P > 0.11) by treatment.Carcass fat IV were greater when 30% DDGS were included in the diet.The withdrawal strategy was successful at lowering the IV compared with pigs fed DDGS throughout; however, as observed in previous studies, it was not successful at fully lowering IV to values similar to pigs fed the control diet throughout.

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plate samples and tended to increase (P < 0.07) in jowl samples for IC pigs compared with barrows, but no difference was detected in IV for belly fat samples.
The change in fatty acid profile and IV between fat stores and by days post-second injection of Improvest are shown in Tables 23 and 24 and Figure 1.The IV of jowl fat is considerably greater than the IV of backfat, belly fat, or clear plate regardless of gender or dietary regimen.Increasing feeding duration from 33 to 51 d post-second injection reduced IV for backfat and belly fat for IC pigs but did not influence IV of jowl or clear plate fat.These results would be expected, because more of the fat in the late finishing period is being deposited in the belly and backfat.The data also demonstrate the difference in conclusion depending on which fat source is being measured.For jowl fat, IV was greater for IC pigs than barrows regardless of diet and did not decrease with days on feed.For backfat and belly fat, increasing days on feed from d 107 to d 125 reduced IV, with IC pigs having a much greater reduction in IV than barrows.
Withdrawing DDGS from the diet prior to harvest, regardless of gender, can regain yield loss and improve IV; however, regardless of withdrawal strategy, feed efficiency was poorer when feeding DDGS.Immunocastrates had reduced carcass yields regardless of diet type compared with barrows, but they also had reduced ADFI and improved ADG, which resulted in improved F/G.Although Improvest can increase IV of fat depots when pigs are harvested at 5 wk post-second injection, extending the length of feeding duration prior to harvest after the second injection returns IV values to levels similar to those of barrows. 1 All values are on a DM basis. 2 First Improvest injection was given on d 39; second Improvest injection was given on d 74. 3 Pigs selected for fat analyses represented the median for each pen (2 pigs/pen). 1All values are on a DM basis. 2 First Improvest injection was given on d 39; second Improvest injection was given on d 74. 3 Pigs selected for fat analyses represented the median for each pen (2 pigs/pen). 1All values are on a DM basis. 2 First Improvest injection was given on d 39; second Improvest injection was given on d 74. 3 Pigs selected for fat analyses represented the median for each pen (2 pigs/pen). 1All values are on a DM basis. 2 First Improvest injection was given on d 39; second Improvest injection was given on d 74. 3 Pigs selected for fat analyses represented the median for each pen (2 pigs/pen). 1All values are on a DM basis. 2 First Improvest injection was given on d 39; second Improvest injection was given on d 74. 3 Pigs selected for fat analyses represented the median for each pen (2 pigs/pen).  All values are on a DM basis. 2 First Improvest injection was given on d 39; second Improvest injection was given on d 74. 3 Pigs selected for fat analyses represented the median for each pen (2 pigs/pen).

Table 3 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on growth performance1

Table 4 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal postimmunocastration on growth performance1Probability, P<

Table 5 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on overall growth performance and weights1

Table 6 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal postimmunocastration on overall growth performance and weights1Probability, P<

Table 7 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on jowl fatty acid analysis for pigs harvested at d 1071,2,3

Table 8 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on jowl fatty acid analysis for pigs harvested at d 1071

Table 9 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on jowl fatty acid analysis for pigs harvested at d 1251,2,3

Table 10 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on jowl fatty acid analysis for pigs harvested at d 1251

Table 11 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on backfat fatty acid analysis for pigs harvested at d 1071,2,3

Table 12 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on backfat fatty acid analysis for pigs harvested at d 1071

Table 13 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on backfat fatty acid analysis for pigs harvested at d 1251,2,3

Table 14 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on backfat fatty acid analysis for pigs harvested at d 1251

Table 15 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on belly fatty acid analysis for pigs harvested at d 107123

Table 16 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on belly fatty acid analysis for pigs harvested at d 1071

Table 17 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on belly fatty acid analysis for pigs harvested at d 1251,2,3

Table 18 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on belly fatty acid analysis for pigs harvested at d 1251

Table 19 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on clear plate fatty acid analysis for pigs harvested at d 1071,2,3 1All values are on a DM basis.2FirstImprovestinjectionwas given on d 39; second Improvest injection was given on d 74.3Pigs selected for fat analyses represented the median for each pen (2 pigs/pen).

Table 20 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on clear plate fatty acid analysis for pigs harvested at d 1071

Table 21 .
Effect of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on clear plate fatty acid analysis for pigs harvested at d 1251,2,3

Table 22 .
Main effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on clear plate fatty acid analysis for pigs harvested at d 1251

Table 23 .
Effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on fatty acid concentrations for pigs harvested at d 1071,2

Table 24 .
Effects of dried distillers grains with solubles (DDGS) withdrawal post-immunocastration on fatty acid concentrations for pigs harvested at d 1251,2