The effects of two true-ileal-digestible lysine concentrations, Optipak®, ractopamine hcl (paylean®), and their combinations, on the growth performance and carcass characteristics of finishing pigs reared in commercial facility

A total of 1,207 pigs (PIC, 337 Ã— 1050) were used in a 28-d experiment in a commercial research barn to evaluate the effects of two true ileal digestible (TID) lysine concentrations, OptipakÂ®, ractopamine HCl, and their combinations, on the growth performance and carcass characteristics of finishing pigs. There were 6 replicates per treatment (with the exception of one treatment that had 5), and 19 to 26 pigs per pen. Pigs were weighed at approximately 220 lb and allotted to six, corn-soybean meal-based dietary treatments. Four diets were formulated to 0.80% TID lysine: a control diet, the control diet with 5 lb/ton of OptipakÂ®, the control diet with 4.5 g/ton of ractopamine HCl, or the control diet with both OptipakÂ® and ractopamine HCl. The two remaining diets were formulated to 0.94% TID lysine and contained 4.5 g/ ton of ractopamine HCl, with or without 5 lb/ton of OptipakÂ®. The treatment structure provided for two 2 Ã— 2 factorial arrangements of treatments. The first factorial utilized the four 0.80% TID lysine diets to evaluate the effects of OptipakÂ® and ractopamine HCl. The second factorial utilized the four diets containing ractopamine HCl to evaluate the effects of TID lysine and OptipakÂ®. Pigs fed diets containing ractopamine HCl had improved (P<0.04) ADG, F/G, and final weight. In the diets containing ractopamine HCl, ADFI tended (P<0.07) to be lower for pigs fed 0.94% TID lysine. There were no other differences in growth performance among the treatments. For carcass characteristics, plant live weight, hot carcass weight, and dressing percentage were improved (P<0.04) for pigs fed ractopamine HCl. Additionally, loin depth increased (P<0.03) when OptipakÂ® was included in the diet. This experiment provides further evidence that ractopamine HCl improves late-finishing growth performance, hot carcass weight, and dressing percentage. Although OptipakÂ® did not improve growth performance, it increased loin depth. The different responses to ractopamine HCl and OptipakÂ® suggest that the incentives for justifying their use need to be evaluated independently.; Swine Day, 2007, Kansas State University, Manhattan, KS, 2007


Summary
A total of 1,207 pigs (PIC, 337 × 1050) were used in a 28-d experiment in a commercial research barn to evaluate the effects of two true ileal digestible (TID) lysine concentrations, Optipak ® , ractopamine HCl, and their combinations, on the growth performance and carcass characteristics of finishing pigs.There were 6 replicates per treatment (with the exception of one treatment that had 5), and 19 to 26 pigs per pen.Pigs were weighed at approximately 220 lb and allotted to six, cornsoybean meal-based dietary treatments.Four diets were formulated to 0.80% TID lysine: a control diet, the control diet with 5 lb/ton of Optipak ® , the control diet with 4.5 g/ton of ractopamine HCl, or the control diet with both Optipak ® and ractopamine HCl.The two remaining diets were formulated to 0.94% TID lysine and contained 4.5 g/ton of ractopamine HCl, with or without 5 lb/ton of Optipak ® .The treatment structure provided for two 2 × 2 factorial arrangements of treatments.The first factorial utilized the four 0.80% TID lysine diets to evaluate the effects of Optipak ® and ractopamine HCl.The second factorial utilized the four diets containing ractopamine HCl to evaluate the effects of TID lysine and Optipak ® .Pigs fed diets containing ractopamine HCl had improved (P<0.04)ADG, F/G, and final weight.In the diets containing ractopamine HCl, ADFI tended (P<0.07) to be lower for pigs fed 0.94% TID lysine.There were no other differences in growth performance among the treatments.For carcass characteristics, plant live weight, hot carcass weight, and dressing percentage were improved (P<0.04) for pigs fed ractopamine HCl.Additionally, loin depth increased (P<0.03) when Optipak ® was included in the diet.This experiment provides further evidence that ractopamine HCl improves latefinishing growth performance, hot carcass weight, and dressing percentage.Although Optipak ® did not improve growth performance, it increased loin depth.The different responses to ractopamine HCl and Optipak ® suggest that the incentives for justifying their use need to be evaluated independently.

Introduction
In modern swine production, the "quest" for technologies to maximize growth rate and 1 Appreciation is expressed to New Horizon Farms for use of pigs and facilities and Richard Brobjorg, Cal Hulstein, and Marty Heintz for technical assistance.efficiency of the terminal market hog is constant.Ractopamine HCl (marketed as Paylean ® , Elanco Animal Health, Indianapolis, IN) is commonly fed to late-finishing pigs to improve growth rate and feed efficiency.A vast amount of research and field data support that appropriate use of this compound in feeding programs is economically justified.The value of the improvements in growth rates and feed conversion associated with its use usually outweigh the costs.
Recently, Hubbard Feeds has been marketing a nutritional supplement (Optipak ® ) to improve the growth rate and carcass characteristics of finishing pigs.Reports on the responses of finishing pigs in the field have stimulated interest in feeding Optipak ® among producers.The suggested benefits are achieved at a considerably lower cost than ractopamine HCl partly because Optipak ® is usually included in a diet containing a lower lysine concentration than that considered necessary in a diet containing Paylean ® .Because a diet containing Optipak ® is less expensive than a Paylean ® diet, some producers have elected to use Optipak ® in their feeding program instead of Paylean ® .However, there is little scientific data to qualify the magnitude or value of the responses to the proprietary blend of nutrients in Optipak ® .Therefore, the objective of this experiment was to evaluate Optipak ® , Paylean ® and their combination at two concentrations of TID lysine.

Procedures
Procedures used in the experiment were approved by the Kansas State University Animal Care and Use Committee.The experiment was conducted in a commercial research finishing facility in southwestern Minnesota.The facility was double curtain sided with pit fans to enable minimum ventilation, and completely slatted flooring over a deep pit for manure storage.Individual pens were 18 × 10 feet.Each pen contained one self-feeder and one cup waterer.
A total of 1,207 pigs were weighed and allotted to one of six dietary treatments.There were 6 replicate pens (with the exception of one treatment that had 5) per treatment.Each pen contained 19 to 26 pigs, depending on the block.Four diets were formulated to 0.80% TID lysine: a control diet, the control diet with 5 lb/ton of Optipak ® , the control diet with 4.5 g/ton of ractopamine HCl, or the control diet with both Optipak ® and ractopamine HCl.The two remaining diets were formulated to 0.94% TID lysine and contained 4.5 g/ton of ractopamine HCl, with or without 5 lb/ton of Optipak ® .Pigs were weighed and feeder measurements taken on d 0, 14, and 28 to determine ADG, ADFI, and F/G.On d 28, pigs were individually tattooed by pen number, and transported to Swift and Co. (Worthington, MN) for carcass data on the following day.
Data were analyzed as a randomized complete block design using the PROC MIXED procedure of SAS with pen as the experimental unit.Least squares means were used to determine differences among treatments.The treatment structure provided for two, 2 × 2 factorial arrangements of treatments.The first factorial utilized the four 0.80% TID lysine diets to evaluate the effects of Optipak ® and ractopamine HCl.The second factorial utilized the four diets containing ractopamine HCl to evaluate the effects of TID lysine and Optipak ® .Additionally, the effect of Optipak was evaluated using a contrast between those treatments that contained Optipak in the feed and those that did not.

Results
Overall (d 0 to 28), pigs fed diets containing ractopamine HCl had improved (P<0.04)ADG, F/G, and final weight.In the diets containing ractopamine HCl, ADFI tended (P<0.07) to be lower for pigs fed 0.94% TID lysine than pigs fed the diets containing 0.8% TID lysine.There were no other differences in growth performance among the treatments.
For carcass characteristics, plant live weight, hot carcass weight, and dressing percentage were improved (P<0.04) for pigs fed ractopamine HCl.Additionally, loin depth increased (P<0.03) when Optipak ® was included in the diet.
In conclusion, other than the trend for lower feed usage, there were no advantages to increasing the TID lysine concentration from 0.80% to 0.94% in diets containing ractopamine HCl.Previous research in this facility has demonstrated a response to higher lysine levels when ractopamine HCl was fed for 21 d prior to market.The lack of response to lysine level in this experiment may have been due to the longer feeding duration or higher feed intake than achieved in the previous experiments.In agreement with earlier research, this experiment provides further evidence that ractopamine HCl improves late-finishing growth performance and carcass characteristics.Growth performance was not improved by adding Optipak ® to the diet; however, Optipak ® increased loin depth.
Therefore, Optipak ® should not be utilized as a substitute for Paylean ® in late-finishing diets.The use of Optipak ® must be justified independently, and may vary depending upon the incentives offered by the packer.Paylean ® fed at a rate of 4.5 g/ton of complete feed. c Optipak ® fed at recommended rate of 5 lb/ton of complete feed.a A total of 1,207 pigs were used in a 28 d experiment to compare the growth performance and carcass characteristics of pigs fed two levels of TID Lys, Optipak ® , 4.5 g/ton Paylean, or the combination prior to slaughter.Six pens of 19 to 26 pigs (5 pens for the 0.94% TID Lys + Optipak ® + Paylean treatment) were assigned to the treatments in a completely randomized design.This provided 148, 140, 144, 146, 149 and 118 pigs per treatment for the 0.80% TID Lys, 0.80% TID Lys + Optipak ® , 0.80% TID Lys + Paylean, 0.80% TID Lys + Paylean + Optipak ® , 0.94% TID Lys + Paylean, and 0.94% TID Lys + Paylean + Optipak ® ; respectively.b Data were analyzed using the initial average weight as a covariate.

Table 1 . Composition of Experimental Diets a
b