# Multivariate evaluation of protein and energy utilization in Peruvian Guinea pigs (Cavia porcellus) under different feeding regimens

## TL;DR

This study examines how different feeding levels affect protein and energy use in guinea pigs, showing that more food boosts growth but reduces protein efficiency.

## Contribution

The study introduces a multivariate approach to analyze protein and energy utilization in guinea pigs under varying feeding conditions.

## Key findings

- Protein retention efficiency declines with ad libitum feeding, indicating protein catabolism.
- Energy metabolizability peaks under ad libitum feeding, especially at 90 days of age.
- PCA and clustering revealed distinct intake-efficiency patterns based on age and feeding level.

## Abstract

Guinea pig (Cavia porcellus) production is vital for food security in Andean countries and increasingly relevant in parts of Africa. Optimizing nutrient utilization is critical to enhance productivity, farmer income, and sustainability. This study employed a multivariate approach to evaluate crude protein and energy digestibility and metabolism in Peruvian guinea pigs under different feeding regimens (maintenance, restricted, and ad libitum) at various ages.

Forty-two male guinea pigs were housed individually in metabolic cages and fed a pelleted diet formulated according to the National Research Council (1995) recommendations. Digestibility and metabolism trials were conducted at 52, 90, and 145 days of age across three feeding levels. Variables including dry matter intake (DMI), gross energy intake (GEI), digestible energy, metabolizable energy (ME), crude protein intake (CPI), and retained protein (RP) were measured. Data were analyzed using principal component analysis (PCA) and hierarchical clustering to identify intake-efficiency patterns.

DMI, GEI, and CPI increased significantly with age and feeding level, strongly correlating with body weight (r > 0.7). Protein retention efficiency (RP/CPI) was highest at maintenance feeding (83.5%) but declined to 73.6% in ad libitum-fed animals at 145 days, indicating protein catabolism when intake exceeded requirements. In contrast, energy metabolizability (ME/GE) peaked under ad libitum feeding (79.5% at 90 days). PCA revealed that PC1 (48.5% variance) was associated with intake and growth, whereas PC2 (18.1%) was linked to metabolic efficiency of protein and energy. Cluster analysis distinguished three groups by feeding level and age, confirming that higher intake reduced protein utilization efficiency despite supporting faster growth.

Multivariate analysis demonstrated that while ad libitum feeding maximized growth and energy metabolizability, it reduced protein retention efficiency, emphasizing the need for balanced protein–energy ratios tailored to the physiological stage. These findings provide a framework for designing age- and intake-specific feeding strategies to enhance nutrient efficiency, meat production, and sustainability in guinea pig systems.