Effect of L-glutamic acid N,N-diacetic acid on the availability of dietary zinc in broiler chickens

Abstract

Chelating agents can be used to improve the nutritional availability of trace minerals within the gastrointestinal tract. This study was conducted to determine the effect of a novel chelating agents, L-glutamic acid N,N-diacetic acid ( GLDA ), a biodegradable alternative to ethylenediaminetetraacetic acid on the nutritional bioavailability of zinc in broilers. Twelve dietary treatments were allocated to 96 pens in a randomized block design. Pens contained 10 Ross 308 male broilers in a factorial design with 6 incremental zinc levels (40, 45, 50, 60, 80, and 120 ppm of total Zn), with and without inclusion of GLDA (0 and 100 ppm) as respective factors. Experimental diets were supplied from day 7 to 21/22 and serum, liver and tibia Zn content were determined in 3 birds per pen. Growth performance and liver characteristics were not affected by dietary treatments, but both supplemental Zn and GLDA enhanced tibia and serum zinc concentration. The positive effect of GLDA was observed at all levels of the dietary Zn addition. The amount of zinc needed to reach 95% of the asymptotic Zn response was determined using nonlinear regression. When GLDA was included in the diet, based on tibia Zn, the same Zn status was achieved with a 19 ppm smaller Zn dose while based on serum Zn this was 27 ppm less Zn. Dietary GLDA reduces supplemental Zn needs to fulfill nutritional demands as defined by tibia Zn and serum Zn response. Considering the positive effect on the nutritional availability of Zn in broilers, GLDA presents an opportunity as biodegradable additive, to reduce Zn supplementation to livestock and thereby reducing Zn excretion into the environment, while fulfilling the nutrition Zn needs of farmed animals.

Tolerance and safety evaluation of L-glutamic acid, N,N-diacetic acid as a feed additive in broiler diets

“…Inclusion of GLDA did not affect serum levels of Mn and Fe, in accordance with previous findings ( Boerboom et al, 2020 ; Boerboom et al, 2021 ). Copper levels when GLDA was fed at 10,000 mg/kg showed numerically higher values compared to the control, which can be explained by the gut integrity effects described above ( Kołodyńska, 2013 ).…”

“…A novel chelator, L-glutamic acid, N,N-diacetic acid ( GLDA ) has shown to increase the nutritional availability of Zn in broilers. In this way, it can be used as a dietary ingredient to safely reduce Zn supplementation in complete feed without compromising the Zn status of the animal, thus contributing to the reduction of environmental trace element pollution of animal production ( Kołodyńska, 2011 ; Wu et al, 2015 ; Boerboom et al, 2020 ; Boerboom et al, 2021 ). In contrast with other chelators such as EDTA, GLDA is readily biodegradable in the environment presenting a low persistence in soils and surface waters.…”

“…Whether GLDA, being a strong chelator as well, would cause such adverse effects and at which dietary concentration remains unclear. The current experiment was conducted aims to evaluate tolerance and safety of the use of GLDA by inclusion in broiler diets at incremental levels up to a dose of 100-fold of the lowest recommended dosed as used in the previous study ( Boerboom et al, 2021 ). In addition, the bioaccumulation of GLDA in different edible tissues was determined to address potential effects on food safety.…”

Dietary l-glutamic acid N,N-diacetic acid improves short-term maintenance of zinc homoeostasis in a model of subclinical zinc deficiency in weaned piglets

“…This was different for liver parameters, indicating that most of the Zn absorbed was quickly released to the circulation for transportation to soft tissues. Overall, this suggests that GLDA holds more Zn absorbable in the presence of high phytate concentrations within the gastrointestinal lumen, which is in line with earlier data on GLDA effects in broiler chickens (21,22) . Comparing the X-axis intercepts of the regression curves of apparently absorbed dietary Zn in GLDA-supplemented vs. control animals yields a (21,22) .…”

“…This sustained solubility results in the chelator complex delivering the mineral to the site of uptake within the gastrointestinal tract, where metal transporters, having a higher chelation strength than the chelator, are then able to absorb the mineral (19,20) . A novel dietary chelator, L-glutamic acid, N, N-diacetic acid (GLDA) has been shown to increase the nutritional availability of Zn in broilers and can be used as a dietary ingredient to improve the availability of Zn in the gastrointestinal tract, similarly to EDTA (21,22) . The benefits of GLDA compared to EDTA are its higher biodegradability and its relatively lower stability constant (10•0 for GLDA v. 16•5 for EDTA) (23,24) .…”