Nutritional programming, the idea that early nutrient intake can shape the development and function of an organism, has garnered significant attention in vertebrate research. However, research on this concept in fish, specifically tilapia, has been relatively scarce.
Nile tilapia (Oreochromis niloticus) is a prominent species in aquaculture, which has seen a global increase in production since the 1990s. Known for their robust disease resistance and efficient growth on formulated feeds, they represent an ideal choice for aquaculture.
However, incorporating high-quality proteins into their diets can be costly, as feeds constitute a substantial portion of aquaculture production expenses, ranging from 50% to 70%. Therefore, reducing protein content while maintaining growth and health is a fundamental goal for both sustainability and profitability in tilapia farming.
In this context, an innovative study by researchers from North Carolina State University, Oregon State University, and Bangladesh Agricultural University explores the influence of early protein restriction on the growth of Nile tilapia, intestinal microbiota, and intestinal transcriptome during the period from 7 to 21 days.
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The study states that “nutritional programming, also known as nutritional conditioning, is the concept that nutrient contributions in the diet or other environmental factors experienced in the early stages of development influence the structure or function of an organism and, therefore, can lead to lifelong changes in key elements of an animal’s physiology, including growth, metabolism, cardiovascular function, and lifespan.”
In this way, altering nutrient levels in the early stages of development can have important implications for immune function, nutrient absorption, and the body’s efficiency in using these nutrients.
Early Protein Restriction and Growth
The study involved feeding Nile tilapia fry with a protein-restricted diet during the first 7 to 21 days of their development, followed by a transition to a controlled protein diet. Specifically, two types of diets were used: an initial diet with 25% restricted crude protein (ST) and an ST diet with 48% controlled crude protein.
After 21 days, the fish transitioned to a controlled growth diet with 25% or 38% crude protein. The results were remarkable. Fish fed a 25% ST diet for 14 days, followed by a 38% GO diet, exhibited significantly greater lengths and weights, along with improved feed efficiency, compared to fish fed the standard 48% ST and 38% GO diet.
This highlights the potential benefits of early protein restriction for enhancing growth and economic viability in tilapia aquaculture.
Intestinal Microbial Flora
The study also examined the intestinal microbial flora of tilapia. While there were no significant differences in the diversity of intestinal microbes between diets, species richness, as indicated by the Shannon index, was notably higher in fry fed the 25% protein diet, regardless of the subsequent GO diet.
This suggests that early protein restriction may have a positive impact on intestinal microbial diversity, which can influence overall fish health and development.
Analysis of the intestinal transcriptome further clarified the effects of early protein restriction. Fish fed a 25% ST diet for 14 days, followed by a 38% GO diet, showed minimal changes in the intestinal transcriptome compared to fish on standard protein diets. However, fish that consumed 25% ST and 38% GO diets for the full 56 days exhibited significant differences in their intestinal transcriptome.
These differences were characterized by gene expression profiles associated with detrimental changes in intestinal physiology, protein metabolism, and immune function, indicating potential health risks.
In conclusion, the study provides valuable insights into the practice of nutritional programming through early protein restriction in Nile tilapia. The findings suggest that a 14-day protein restriction during the early stages of development can improve growth, feed efficiency, and intestinal microbial diversity while maintaining healthy intestinal function.
However, prolonged protein restriction beyond this critical period may have adverse effects on fish growth and overall health. These results have significant implications for the aquaculture industry, where optimizing feed efficiency and reducing production costs are top priorities. By strategically applying early protein restriction, tilapia producers have the potential to unlock growth potential and enhance the sustainability of their operations.
Russell J. Borski
Department of Biological Sciences
North Carolina State University
Raleigh, NC, United States of America
Reference (open access):
Deck CA, Salger SA, Reynolds HM, Tada MD, Severance ME, Ferket P, et al. (2023) Nutritional programming in Nile tilapia (Oreochromis niloticus): Effect of low dietary protein on growth and the intestinal microbiome and transcriptome. PLoS ONE 18(10): e0292431. https://doi.org/10.1371/journal.pone.0292431