Effects of Monosodium Glutamate and AminoGut on Nursery Pig Effects of Monosodium Glutamate and AminoGut on Nursery Pig Performance Performance

Summary A total of 1,134 nursery pigs (PIC 359 × 1050, 10.9 ± 0.46 lb BW) were used in a 42-d growth study to determine the effects of monosodium glutamate (MSG), AminoGut, and glutamine (Ajinomoto Heartland, LLC, Chicago, IL) on growth performance. Pigs were fed 1 of 6 dietary treatments. Treatments were fed in 2 phases from d 0 to 7 and 7 to 21. The dietary treatments contained 0, 0.5, 1.0, or 1.5% MSG fed in both phases, 0.8 and 0.6% AminoGut fed in phase 1 and 2, respectively, or a combination of 1.0% MSG and 0.4% glutamine fed in both phases. A common post-treatment diet was fed from d 21 to 42. Phase 1 was in pellet form and the subsequent phases were in meal form. Pigs were randomly allotted to pens at weaning and pens were then allotted to treatment according to BW in a randomized complete block design with 7 replications per treatment. During phase 1 (d 0 to 7), there was no evidence for difference ( P > 0.553) for ADG, ADFI, or F/G with the addition of MSG, AminoGut, or MSG+Gln. In phase 2 (d 7 to 21), the addition of MSG did not impact ADG or ADFI ( P > 0.163), but resulted in a marginal improvement (linear, P = 0.097) in F/G. Pigs fed AminoGut demonstrated improved ADG ( P < 0.05) compared to all other treatments and increased ( P < 0.05) ADFI compared to pigs fed 0.5, 1.0, or 1.5% MSG. There was no evidence for difference ( P > 0.105) during the common post-treatment period, overall period, or in final BW. Results from this study indicate that feeding MSG alone or with Gln does not result in improved post-weaning growth performance. AminoGut provided a growth and intake response from d 7 to 21 post-weaning. While the increase in BW for pigs fed AminoGut was maintained through the common phase, the response was no longer significant. Further investigation is required to determine the appropriate timing and feeding duration of AminoGut in the nursery.


Introduction
Glutamine (Glu) and glutamate (Gln), though both considered non-essential amino acids, are highly important fuel sources for the small intestine.These amino acids may be limited during the post-weaning period as pigs transition from sow's milk (a good Swine Day 2017 source of these amino acids) to dry diets.Furthermore, with the gastrointestinal stress associated with weaning, dietary supplementation of Glu and Gln may prove beneficial to help the pig maintain intestinal health and function.Previous studies conducted at Kansas State University4 evaluated the effects of monosodium glutamate on nursery pig performance with and without balancing for Na and Cl content.When Na was not controlled, increasing MSG decreased nursery pig performance, whereas, performance was maintained when Na was balanced.Furthermore, Gonçalves et al. 5 investigated the effects of AminoGut (Ajinomoto Heartland, Inc., Chicago, IL), a combination of glutamate and glutamine, and reported improvements in ADG and F/G when feeding from d 10 to 24 post-weaning.Therefore, the objective of this study was to evaluate the effects of MSG during the post-weaning period and its combination with Gln, as well as AminoGut on performance of pigs.

Procedures
The Kansas State University Institutional Animal Care and Use Committee approved the protocol used in this experiment.The trial was conducted at a commercial nursery research facility in southwest Minnesota.The barn was mechanically ventilated and had completely slatted flooring and deep pits for manure storage.Each pen was equipped with a 6-hole, stainless-steel, dry self-feeder and a pan waterer allowing ad libitum access to feed and water.Diets were manufactured at two commercial feed mills (Hubbard, Mankato, MN, for phase 1; and New Horizon Farms, Pipestone, MN, for phases 2 and 3).Feed additions to each individual pen were delivered and recorded by a robotic feeding system (FeedPro; Feedlogic Corp., Willmar, MN).Samples of each diet were analyzed for proximate analysis as well as Na, Cl, and salt content (Ward Laboratory, Kearney, NE).
A total of 1,134 nursery pigs (PIC 280 × 1050, initially 10.9 ± 0.46 lb BW) were used in a 42-d growth trial with 27 pigs per pen and 7 replications per treatment.Pigs were weaned at approximately 16 d of age and were randomly allotted to pens upon arrival to the nursery.Pens were then blocked by BW within weaning day and allotted to one of 6 dietary treatments fed in 2 phases from d 0 to 7 and 7 to 21.The dietary treatments contained 0, 0.5, 1.0, or 1.5% MSG fed in both phases, 0.8 and 0.6% AminoGut fed in phases 1 and 2, respectively, or a combination of 1.0% MSG and 0.4% glutamine fed in both phases.All phases were formulated to balance for Na and Cl content while meeting the Na and Cl requirements for each phase.With increasing MSG, Na and Cl were balanced by the addition of sodium bicarbonate or potassium chloride, with salt removed as needed.A common post-treatment diet was fed from d 21 to 42.Phase 1 diets were fed in pelleted form.Phase 2 diets and the common diet were fed in meal form with the 0 and 1.5% MSG diets blended in the robotic feeding system to create the 2 intermediate MSG treatments.Pens were weighed and feed disappearance was measured on d 0, 7, 14, 21, 28, 35, and 42 to determine ADG, ADFI, and F/G.Data were analyzed using the PROC GLIMMIX procedure of SAS version 9.4 (SAS Institute, Inc., Cary, NC) with pen considered the experimental unit.Linear and quadratic contrasts were applied for the MSG treatments.LSMEANS was used for mean separation.Results were considered significant at P ≤ 0.05 and tendencies between P > 0.05 and P ≤ 0.10.

Results and Discussion
Dietary treatment analysis generally matched formulated nutrient levels.Sodium concentration was variable across treatments although within analytical variation (Tables 3  and 4).The MSG utilized was the same product used in previous MSG studies and contained 19.2% Na.
During phase 1 (d 0 to 7), there was no evidence for difference (P > 0.552) for ADG, ADFI, or F/G with the addition MSG, AminoGut, or MSG+Gln (Table 7).In phase 2 (d 7 to 21), the addition of MSG did not result in evidence for differences (P > 0.163) in ADG or ADFI, but resulted in a marginal improvement (linear, P = 0.097) in F/G.Pigs fed AminoGut demonstrated improved (P < 0.05) ADG compared to all other treatments.In addition, pigs fed AminoGut had improved (P < 0.05) ADFI compared to pigs fed 0.5, 1, or 1.5% MSG and similar intake ((P > 0.05) to those fed 0% MSG or MSG+Gln.There was no evidence for difference (P > 0.105) during the common post-treatment period or the overall period.Furthermore, no evidence for difference (P > 0.906) was observed in BW until d 21 where pigs fed increasing AminoGut had increased BW compared to MSG fed pigs, with MSG+Gln fed pigs having intermediate BW.There was no evidence for difference (P = 0.200) in final BW.However, the advantage in BW on d 21 of 0.9 lb per pig for pigs fed AminoGut compared to the control was 1.1 lb per pig on d 42.
Results from this study suggest that increasing MSG from 0 to 1.5% did not improve nursery growth performance.This response is similar to results by Clark et al. 6 in which MSG did not elicit evidence for differences when diets were balanced for Na and Cl.Feeding AminoGut resulted in improved growth and feed intake in phase 2, similar to the response of Gonçalves et al. 5 Further research should evaluate feeding duration and the amount of AminoGut added to the diet during the post-weaning period.

Table 2 ,
continued.Phases 2 and 3 diet composition (as-fed basis) 1 Antibiotics were pulsed during the common phase with no medication fed from d 21 to 28 and antibiotics included during d 28 to 42. 8

Table 5 .
Effects of monosodium glutamate, AminoGut, and glutamine on nursery pig performance 1