Effects of Monosodium Glutamate on 14-to 56-lb Nursery Pigs Effects of Monosodium Glutamate on 14-to 56-lb Nursery Pigs

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Introduction
Glutamate, though considered a nonessential amino acid, plays an important role in gut function, particularly by serving as an energy substrate for intestinal villi cells. 4When pigs are weaned, glutamate may help alleviate the severity of the effects associated with intestinal stresses such as diarrhea and reduced growth performance.There is limited research investigating the impact of monosodium glutamate (MSG) on swine growth Swine Day 2017 performance.However, Rezai et al. 5 observed improved growth performance in nursery pigs supplemented with up to 4% MSG.In a previous experiment, Clark et al. 6 observed that increasing dietary MSG negatively affected nursery pig growth; however, Na was not balanced with increasing MSG.Thus, the response may have been a negative effect of excess Na rather than a response to MSG.Therefore, the objective of this study was to identify the effects of increasing MSG on nursery pig performance while balancing for Na and Cl content.

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 research facility that is owned and operated by Kalmbach Feeds, Inc. (Sycamore, OH).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.
A total of 700 nursery pigs (PIC C-29 × 1050, initially 13.6 lb BW) were used in a 42-d growth study trial with 10 pigs per pen and 14 replications per treatment.Pigs were weaned at approximately 21-d of age and allotted to pens upon weaning.Pens were blocked by BW and allotted to one of 5 dietary treatments: 0, 0.5, 1.0, 1.5, and 2.0% MSG.Pigs were fed in three phases from d 0 to 14, 14 to 28, and 28 to 42.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.Phase 1 diets were pelleted, while phases 2 and 3 were fed in meal form.Diets (Tables 1-3) were formulated to balance Na and Cl content with increasing MSG using salt, sodium bicarbonate, and potassium chloride.Diets were formulated at 1.40, 1.35, and 1.25% SID Lys in phases 1, 2, and 3, respectively, with other essential amino acids formulated to be greater than the pig's estimated requirements.Diets were manufactured at a commercial feed mill (Upper Sandusky, OH).Samples of each diet were analyzed for proximate analysis as well as Na, Cl, and salt content (Ward Laboratory, Kearney, NE).Data were analyzed using the PROC GLIMMIX procedure of SAS version 9.4 (SAS Institute, Inc., Cary, NC) with pen considered the experimental unit.Initial BW was used as a covariate.Linear and quadratic contrasts were applied to evaluate the effect of MSG.Results were considered significant at P ≤ 0.05 and tendencies between P > 0.05 and P ≤ 0.10.

Results and Discussion
Dietary analyses generally matched formulated levels of nutrients (Tables 4-6).Some of the results showed slight variation in the Na concentration, particularly in the pelleted phase 1 diets.
During phase 1 (d 0 to 14), increasing MSG did not influence ADG, ADFI, or F/G (Table 7).In phase 2 (d 14 to 28), there were no significant differences between dietary treatments for ADG or ADFI; however, F/G tended (quadratic, P < 0.079) to improve with increasing MSG.For phase 3 (d 28 to 42), there was no dietary effect on ADG or ADFI, but F/G became poorer (P < 0.002) with increasing MSG.For the overall nursery period (d 0 to 42), increasing MSG had no effect on ADG or ADFI and tended (quadratic, P < 0.092) to result in poorer F/G.No significant differences were observed in BW between any of the dietary treatments.
Results from this study suggest that increasing MSG from 0 to 2% in the diet did not affect nursery pig growth performance.Slight F/G differences were observed in intermediate phases 2 and 3, but these did not have a major impact on the overall nursery performance.Further research is needed to determine the effects and optimal feeding level of MSG for nursery pigs.In the previous experiment, 6 intake and growth performance were negatively affected with increasing dietary MSG; however, diets were not balanced for Na, thus diets increased in sodium concentration as MSG increased.Therefore, it is critical to determine the relationship between Na and glutamate within the gut to effectively administer MSG to alleviate the negative effects observed during the post-weaning period.