Body Mass and Growth Rates Predict Protein Intake Across Animal Species and Developmental Stages

Core Concepts

Protein consumption rates decline systematically during animal ontogeny, correlating with decreases in specific growth rates, and this pattern holds across diverse animal species.

Abstract

The study investigated how macronutrient (protein and carbohydrate) intake targets change during ontogeny in the South American locust, Schistocerca cancellata. The key findings are:

Younger locust instars (1st to 4th) had protein-biased consumption, with the 3rd instar exhibiting the highest protein to carbohydrate (p:c) ratio of 1.37p:1c. In contrast, older juveniles and adults became carbohydrate-biased, selecting a p:c ratio of 1p:2.66c.

Mass-specific protein consumption rate decreased steadily through ontogeny, with a roughly four-fold decrease in adults compared to first instars. This decline in protein consumption correlated strongly with the decrease in specific growth rate during development.

Protein consumption rates scaled hypometrically with body mass, both during ontogeny and across diverse animal species. In contrast, carbohydrate consumption rates scaled closer to isometrically.

Field-collected locusts had 50-90% higher carbohydrate consumption rates compared to lab-reared locusts, likely due to higher activity levels and metabolic rates in the field. However, protein consumption rates did not differ between lab and field populations.

The results demonstrate that declining protein requirements during ontogeny, driven by decreasing growth rates, is a general pattern across animals. This provides a new paradigm for understanding nutritional ecology and the evolution of macronutrient intake strategies.

Stats

Mass-specific protein consumption rate decreased steadily through ontogeny in locusts.
Mass-specific carbohydrate consumption rates were about 30% higher for the first two locust instars compared to older animals.
Field-collected 6th instar locust nymphs had ~23% higher mass-specific resting oxygen consumption rate than lab-reared 6th instar nymphs.

Quotes

"Protein consumption rates scaled predictably and hypometrically, demonstrating a new scaling rule key for understanding nutritional ecology."
"Combining our results with the available data for animals, both across species and during ontogeny, protein consumption scaled predictably and hypometrically, demonstrating a new scaling rule key for understanding nutritional ecology."
"Field-collected locusts had 50-90% higher carbohydrate consumption rates compared to lab-reared locusts, likely due to higher activity levels and metabolic rates in the field."

Key Insights Distilled From

Body mass and growth rates predict protein intake across animals

by Talal,S., Ha... at www.biorxiv.org 06-24-2023

https://www.biorxiv.org/content/10.1101/2023.06.20.545784v1

Deeper Inquiries

How do ecological conditions that affect growth and reproduction influence the ontogenetic patterns of macronutrient intake?

Ecological conditions that impact growth and reproduction can significantly influence the ontogenetic patterns of macronutrient intake in animals. For example, in resource-limited environments where growth is constrained, animals may adjust their macronutrient intake to prioritize essential nutrients for survival and reproduction. This could lead to alterations in the balance of protein and carbohydrates consumed during different life stages. Additionally, stressors such as temperature fluctuations, food availability, and predation risk can also impact macronutrient intake patterns. For instance, in the study of South American locusts, field-collected nymphs exhibited higher carbohydrate consumption rates compared to lab-reared nymphs, possibly due to increased energy demands and metabolic rates in response to environmental stressors.

What are the potential evolutionary drivers behind the interspecific variation in the scaling of protein consumption with body size?

The interspecific variation in the scaling of protein consumption with body size can be driven by evolutionary factors related to species-specific ecological niches, dietary preferences, and life history strategies. Different species have evolved to thrive in diverse environments with varying food sources, leading to adaptations in macronutrient intake patterns. For example, species that rely on high-energy activities like flight may have lower protein requirements relative to carbohydrates. Additionally, evolutionary pressures such as competition for resources, predation risk, and reproductive strategies can shape the optimal macronutrient intake ratios for different species. The scaling of protein consumption with body size may reflect the evolutionary trade-offs between growth, reproduction, and survival in response to ecological challenges.

Could age-specific dietary recommendations for humans and livestock be informed by the general patterns of ontogenetic changes in macronutrient requirements observed across animals?

The general patterns of ontogenetic changes in macronutrient requirements observed across animals can provide valuable insights for developing age-specific dietary recommendations for humans and livestock. Understanding how macronutrient intake shifts during different life stages can help optimize nutrition and promote healthy growth and development. For example, infants and young children may have higher protein requirements for growth and development, while older individuals may benefit from a more balanced protein to carbohydrate ratio to support metabolic functions and prevent age-related muscle loss. By considering the ontogenetic patterns of macronutrient intake across species, researchers and nutritionists can tailor dietary guidelines to meet the specific needs of individuals at different life stages, promoting overall health and well-being.