Advances in animal nutrition research highlight the need for accurate yet welfare-conscious methods to assess nutrient requirements. Traditional approaches to determining protein needs in dogs are often invasive, involving procedures such as blood sampling or confinement in metabolic chambers. This study evaluated a minimally invasive, cage-free protocol designed to estimate protein requirements in adult dogs while prioritizing animal welfare. The method utilized the indicator amino acid oxidation technique, employing the stable isotope 13C-phenylalanine as a tracer. This approach measures the utilization of dietary protein by analyzing carbon isotopes in exhaled breath. Dogs were trained to breathe calmly through specially adapted masks that enabled comfortable, stress-free breath sample collection while housed in standard kennel environments. Results indicated that this method produced consistent and reliable data, comparable to traditional techniques, but without the need for blood collection or physical restraint. These findings demonstrate that the feeding schedule, isotope enrichment protocol, and breath-sampling procedure together constitute a valid, ethical, and practical approach for accurately assessing protein requirements in dogs, offering a welfare-friendly alternative for companion animal nutrition research.

Read the full article in the Journal of Animal Science.