Arginine: Assessing the use of higher inclusion levels in broiler diets

Over the past two decades, there has also been a growing interest in the effects of this amino acid on

the gastrointestinal tract.

Arginine and its derivatives have been consistently shown to possess properties that promote and restore gut health, such as:

• accelerating mucosal regeneration and recovery from gastroenteric disorders
• improving epithelial integrity and barrier function
• immunomodulation
• anti-inflammatory activity
• inhibition of enteric pathogens
• restoration of beneficial microbiota

In regards to animal nutrition, arginine is commonly considered a semi-essential or conditionally essential amino acid for adult mammals. Meanwhile chickens rely on dietary arginine to meet their requirements.

This is related to the fact that mammals are ureotelic (i.e., urea-excretion) animals which can endogenously produce de novo arginine through the action of urea cycle enzymes. On the contrary, bird species are uricotelic (i.e., uric acid excretion) organisms unable to complete the urea cycle.

Extensive research has shown that arginine requirements in broilers can substantially vary according to dietary composition and environmental conditions.

Arginine supplementation above recommended levels, such as those published by the NRC or breeding companies, has been shown to be beneficial for broiler health, growth performance, and processing traits.

Arginine Levels: Research

A study was designed to evaluate the effects of arginine supplementation (i.e., total arginine to total lysine ratio of 1.20 instead of the 1.06–1.08 ratio recommended by breeding companies)  on broiler growth performance. Assessing its impact on:

hepatic function,

blood metabolic profiles,

as well as on the intestinal microbiota.

To achieve this purpose, a diet supplemented with L-arginine was administered for 49 d.

Results

Compared to control birds, those receiving the arginine supplement performed significantly better and exhibited: a higher final body weight at D49 (3778g vs. 3937 g;  P < 0.001), higher growth rate (76.15g versus 79.46 g of body weight gained daily;  P < 0.001), and a lower cumulative feed conversion rate (1,808 vs. 1,732;  P < 0.05).

Plasma concentrations of arginine, betaine, histidine, and creatine were higher in the supplemented birds than in their control counterparts, as were creatine, leucine, and other essential amino acids in the liver.

In contrast, leucine concentration in the cecal content was lower for the supplemented birds.

Reduced alpha diversity and relative abundance of Firmicutes and Proteobacteria (specifically Escherichia coli), as well as a higher abundance of Bacteroidetes and Lactobacillus salivarius were found in the cecal content of supplemented birds.

Conclusions

The improvements observed regarding growth yield corroborate the advantages of arginine supplementation in broiler nutrition.

It can be hypothesized that the performance improvement found in this study is associated with increased availability of arginine, betaine, histidine and creatinine in plasma and liver. As well as due to the the capacity of additional dietary arginine to potentially improve gut conditions and benefit the microbiota of supplemented birds.

However, the latter, among with other research questions that arose from this study, still require further research to be clearly elucidated.

You may also like to read:  “Threonine, arginine and glutamine: Influence on broiler intestinal physiology.”

Source:

Brugaletta, G., Zampiga, M., Laghi, L. et al. Feeding broiler chickens with arginine above recommended levels: effects on growth performance, metabolism, and intestinal microbiota. J Animal Sci Biotechnol 14, 33 (2023)