Effects of Different Feed Mills and Conditioning Temperature of Pelleted Diets on Nursery Pig Performance and Feed Preference from 14 to 50

In Experiment 1, pens of pigs were randomly allotted to 1 of 3 dietary treatments with 10 pens per treatment and 7 pigs per pen. The 3 dietary treatments used the identical corn-soybean meal–based formulation and were mixed from the same batch of ingredients. Experimental diets were: (1) feed mixed at mill B but pelleted in mill A; (2) feed mixed and pelleted at mill B; and (3) feed mixed at mill B and fed in meal form. Experiment 2 was a feed preference study where pens of pigs were randomly allotted to the same diets as Experiment 1 with 4 pens per treatment and 7 pigs per pen. Pens contained 2 feeders, each containing 1 of 3 treatment diets. Feeders were rotated once daily within each pen for the entire 33-d study with three diet comparisons tested: 1 vs. 2, 1 vs. 3, and 2 vs. 3.


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Effects of Different Feed Mills and Conditioning Temperature of Pelleted Diets on Nursery Pig Performance and Feed Preference from 14 to 50 lb J.A. De Jong, J.M. DeRouchey, M.D. Tokach, R.D. Goodband, and S.S. Dritz1 Summary A total of 644 pigs (PIC 1050 or 327 × 1050, initial BW~14 lb) were used in 3 experiments to determine possible explanations for poorer pig performance in previous studies with pigs fed pelleted diets compared with those fed meal diets.Therefore, we examined feed pelleted from different mills as well as conditioning temperature as factors influencing our previous results.
In Experiment 1, pens of pigs were randomly allotted to 1 of 3 dietary treatments with 10 pens per treatment and 7 pigs per pen.The 3 dietary treatments used the identical corn-soybean meal-based formulation and were mixed from the same batch of ingredients.Experimental diets were: (1) feed mixed at mill B but pelleted in mill A; (2) feed mixed and pelleted at mill B; and (3) feed mixed at mill B and fed in meal form.Experiment 2 was a feed preference study where pens of pigs were randomly allotted to the same diets as Experiment 1 with 4 pens per treatment and 7 pigs per pen.Pens contained 2 feeders, each containing 1 of 3 treatment diets.Feeders were rotated once daily within each pen for the entire 33-d study with three diet comparisons tested: 1 vs. 2, 1 vs. 3, and 2 vs. 3.
In Experiment 3, pens of pigs were randomly allotted to 1 of 5 dietary treatments and fed for 16 d with 14 pens per treatment and 5 pigs per pen.Similar to Experiment 1, all diets used the identical corn-soybean meal-based formulation and were mixed from the same batch of ingredients.The experimental diets were: (1) feed mixed at mill A and fed in meal form; (2) feed mixed at mill A, but pelleted at mill B; (3), (4), and (5) feed mixed and pelleted at mill A at a conditioning temperature of 140, 160, or 180˚F, respectively.
In Experiment 1, pigs fed the mill-B pelleted diet had the greatest (P < 0.05) ADG, whereas pigs fed the mill-A pelleted diet had the lowest (P < 0.05) ADG, with the meal diet from mill B intermediate (Table 6).There were no differences in ADFI among the three experimental diets.The mill-A pelleted diet significantly worsened (P < 0.05) F/G and final BW compared with the mill-B pelleted diet, whereas the mill-B mash diet only tended (P < 0.06) to worsen F/G compared with the mill-B pelleted diet.
In Experiment 2 for comparison 1, pigs consumed more (P < 0.05) of the mill-B pelleted diet than the mill-A pelleted diet, which translated into pigs eating 70% of

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their daily intake from the mill B pellet (Table 7).For comparison 2 and 3, pigs fed either the mill-A or mill-B pellet consumed more feed (P < 0.05) than the mill B diet fed in mash form, with the pellets equated to 90% of their daily intake.
For Experiment 3, there were no differences among the three diets pelleted under increasing conditioning temperatures at mill A, so they were combined for analysis (Table 8).Pigs fed the meal diet had improved (P < 0.05) ADG compared with pigs fed the mill-A pellet with the mill-B pellet fed pigs intermediate.For ADFI, both mill-B and mill-A pellet-fed pigs had reduced (P < 0.05) intake compared with the meal diet but

Introduction
Pelleting swine diets typically improves pig growth performance and feed efficiency by approximately 4 to 6%.In recent Kansas State University studies, however, pigs fed pelleted diets had decreased ADG and poorer F/G than those fed meal-based diets.These differences in the response to pelleting were unexpected.The pellets used in these studies had no visible characteristics that might be responsible for the differences in performance.We questioned if something inherent in the pelleting process at one mill might be responsible for the differences; therefore, our objective was to compare pig performance and preference for the same diet pelleted at different feed mills, then to determine if conditioning temperatures might be the reason for the change in pig performance.

Procedures
The Kansas State University Institutional Animal Care and Use Committee approved the protocols used in these experiments.The studies were conducted at the K-State Swine Teaching and Research Center and Segregated Early Weaning Facility in Manhattan, KS.
A total of 644 pigs (PIC 1050 or 327 × 1050, initially ~14 lb) were used in three experiments.In all experiments, pigs were randomly allotted to pens based on initial pig weight.
In Experiment 1, pens of pigs were randomly allotted to 1 of 3 dietary treatments with 10 pens per treatment and 7 pigs per pen.Experimental diets were fed for 42 d.The 3 dietary treatments used identical corn-soybean meal-based formulations and were batched from similar lots of ingredients (Table 1).Experimental treatments were: (1) feed mixed at mill B but pelleted in mill A; (2) feed mixed and pelleted at mill B; and (3) feed mixed at mill B and fed in meal form.

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Experiment 2 was a feed preference study in which pens of pigs were randomly allotted to the same treatments as Experiment 1, with 4 pens per treatment and 7 pigs per pen.Pens contained two feeders, each feeder containing 1 of 3 treatment diets.Feeders were rotated once daily within each pen for the entire 33-d study, with three diet comparisons tested: 1 vs. 2, 1 vs. 3, and 2 vs. 3.
In Experiment 3, pens of pigs were randomly allotted to 1 of 5 dietary treatments and fed for 16 d with 14 pens per treatment and 5 pigs per pen.The 5 dietary treatments used the identical corn-soybean meal-based formulation.Batches of feed were made for the Phase 1 and 2 diets, respectively, then sacked, and bags were pulled randomly from each batch to create the base feed for each treatment.The experimental treatments were: (1) feed mixed at mill A and fed in meal form; (2) feed mixed at mill A, but pelleted at mill B (conditioning temperature of 143˚F); and (3), (4), and (5) feed mixed and pelleted at mill A at a conditioning temperatures of 140, 160, or 180˚F.
In Experiment 1, each pen contained a 4-hole, dry self-feeder and a nipple waterer to provide ad libitum access to feed and water.Pens had wire-mesh floors and allowed approximately 3 ft 2 /pig.Pig weight and feed disappearance were measured on d 0, 7, 14, 21, 26, 33, and 42 of the trial to determine ADG, ADFI, and F/G.In Experiment 2, each pen contained two, 2-hole, dry self-feeders and a nipple waterer to provide ad libitum access to feed and water.Pens were similar to Experiment 1, and pigs were weighed and feed disappearance was measured on d 0, 7, 14, 21, 26, and 33.In Experiment 3, pigs were provided unlimited access to feed and water by way of a 4-hole dry self-feeder and a cup waterer in each pen (5 ft × 5 ft).Pig weight and feed disappearance were measured on d 0, 6, 13, and 16 of the trial to determine ADG, ADFI, and F/G.Complete diet samples were collected and submitted to Ward Laboratories, Inc. (Kearney, NE) for analysis of DM, CP, ADF, NDF, ADF, NDF, Ca, P, crude fat, and ash.In addition, diet samples from Experiment 1 were analyzed for total and available lysine.Percentage fines and pellet durability index (PDI) were also determined for pelleted diets in all three experiments.Bulk density was determined for all diets and angle of repose for all mash diets.Data were analyzed using PROC MIXED in SAS (SAS Institute, Inc., Cary, NC) with pen as the experimental unit.The LSMEANS procedure was used to determine the mean differences of treatments.Statistics were considered significant at P < 0.05 and tendencies at P < 0.10.

Results and Discussion
As expected, chemical analysis of complete diets from all three trials revealed no notable differences between treatments within experiment (Tables 2 and 3).Diets analyzed from Experiment 1 showed no differences in total and available lysine.Pellet durability and percentage fines were also similar among pelleted diets within experiment (Tables 4 and 5).
Overall in Experiment 1, pigs fed the mill-B pelleted diet had the greatest (P < 0.05) ADG, whereas pigs fed the mill-A pelleted diet had the lowest (P < 0.05) ADG, with the meal diet from mill B intermediate (Table 6).There were no differences in ADFI SWINE DAY 2014 among the three experimental diets.The mill-A pelleted diet significantly worsened (P < 0.05) F/G and final BW compared with the mill-B pelleted diet, whereas the mill-B mash diet only tended (P < 0.06) to worsen F/G compared with the mill-B pelleted diet.
In Experiment 2 for comparison 1, pigs consumed more (P < 0.05) of the mill-B pelleted diet than the mill-A pelleted diet, which translated into pigs eating 70% of their daily intake from the mill B pellet (Table 7).For comparison 2 and 3, pigs fed either the mill-A or mill-B pellet consumed more feed (P < 0.05) than the mill B diet fed in mash form, with the pellets equated to 90% of their daily intake.
For Experiment 3, there were no differences among the three diets pelleted under increasing conditioning temperatures at mill A, so they were combined for analysis (Table 8).Pigs fed the meal diet had improved (P < 0.05) ADG compared with pigs fed the mill-A pellet, with the mill-B pellet fed pigs intermediate.For ADFI, both mill-B and mill-A pellet-fed pigs had reduced (P < 0.05) intake compared with the meal diet but improved (P < 0.05) F/G.Final BW was reduced when pigs were fed the mill-A pelleted diet compared with the mash diet, with the pigs fed the mill-B pellet intermediate.
In conclusion, the same diet when produced at different feed mills may affect pig performance.In our study, Experiment 3 demonstrated that the conditioning temperature range of pelleted diets did not affect nursery pig growth performance; thus, differences in pelleting temperatures do not seem to explain the inter-mill growth performance and preference differences exhibited in the first two experiments.We speculate other factors that may explain the difference include mill operator experience level, post-pelleting handling techniques, pellet cooling systems, or humidity and room temperatures during the pelleting process.Additional research is needed to better understand how mill-tomill variation affects growth performance of pigs.

Table 2 .
Chemical analysis of diets, Experiments 1 and 2 (as-fed basis) 1 A composite sample consisting of 3 subsamples was used for analysis.Samples from Experiments 1 and 2 were combined for analysis because they were batched and pelleted together at the mill.
1 2 Available lysine has not been bound and is still available to the pig.

Table 7 .
Effects of mill on feed intake preference of pelleted and meal diets in nursery pigs, Experiments 2 1

Table 8 .
Effects of mill on nursery pig growth performance, Experiments 3 1,2 A total of 350 pigs (PIC 1050 barrows, initially 14 lb BW) were used in a 16-d growth trial with 5 pigs per pen and 14 pens per treatment. 2Pellets with different conditioning temperatures from mill A were not significantly different and were combined for statistical analysis.
1 3 Shows the overall treatment effect.