One of the most common questions cat owners ask is, “What is the best food for my cat?” The answer starts with understanding the cat’s unique metabolic biology. In this guide, you will find the scientific basis of feline nutritional physiology, life-stage requirements, and the core principles behind the VetKriter scoring system.
1. Why Are Cats Different? Obligate Carnivore Metabolism
Cats are obligate carnivores, meaning they evolved on a strictly animal-based diet. This creates important nutritional differences from dogs and humans.
1.1 Metabolic Characteristics
| Feature | Cat | Dog | Clinical Relevance |
|---|
| Feeding Type | Obligate carnivore | Facultative carnivore | Cats must receive animal-derived protein |
| Taurine Synthesis | Insufficient | Adequate | Deficiency may lead to cardiac and ocular disease |
| Arachidonic Acid | Cannot synthesize adequately | Can synthesize | Animal fat is essential |
| Vitamin A | Cannot efficiently convert beta-carotene | Can convert beta-carotene | Preformed vitamin A is required |
| Niacin | Cannot synthesize sufficiently from tryptophan | Can synthesize | Dietary niacin is required |
| Starch Digestion | Limited | Better developed | Lower carbohydrate loads are preferable |
1.2 Natural Dietary Profile
Analysis of natural prey such as mice and small birds shows the following nutrient pattern:
| Nutrient (Dry Matter) | Natural Prey | Typical Dry Food | Typical Wet Food |
|---|
| Protein | 52-63% | 30-45% | 40-55% |
| Fat | 22-36% | 15-25% | 20-35% |
| Carbohydrate | 1-2% | 25-50% | 5-15% |
| Moisture | 65-75% | 6-10% | 70-85% |
💡 Scientific fact: Cats are biologically adapted to a high-protein, high-fat, very low-carbohydrate diet. Commercial foods should be interpreted against that natural reference point.
2. Macronutrient Requirements
2.1 Protein
For cats, protein is not only essential for tissue maintenance; it is also a major metabolic fuel source.
| Reference | Kitten | Adult | Gestation/Lactation |
|---|
| AAFCO (2023) | 30% DM | 26% DM | 30% DM |
| FEDIAF (2021) | 28% DM | 25% DM | 28% DM |
| Optimal Range | 38-50% DM | 35-45% DM | 38-50% DM |
Why Does Protein Quality Matter?
| Protein Source | Biological Value | Digestibility | Evaluation |
|---|
| Egg | 100 (reference) | 97% | Excellent |
| Chicken / turkey meat | 92-100 | 92-95% | Excellent |
| Fish | 92 | 90-95% | Excellent |
| Beef | 80-90 | 90-92% | Very good |
| Lamb | 75-85 | 88-92% | Good |
| Soy protein | 67 | 75-80% | Moderate (limited value for cats) |
| Corn gluten | 54 | 70-75% | Low (not ideal for cats) |
⚠️ Important: Plant protein sources such as soy and corn gluten have lower biological value for cats and a less favorable essential amino acid profile. A label may look protein-rich on paper while still failing to provide biologically appropriate nutrition.
2.2 Fat
| Parameter | Minimum | Optimal | Explanation |
|---|
| Total Fat | 9% DM | 15-25% DM | Energy source and essential fatty acids |
| Linoleic Acid (Omega-6) | 0.5% DM | 1-2% DM | Skin and coat support |
| Arachidonic Acid | 0.02% DM | 0.05-0.1% DM | Must come from animal sources |
| EPA + DHA (Omega-3) | - | 0.1-0.3% DM | Anti-inflammatory and neurologic support |
2.3 Carbohydrate
Cats digest carbohydrate less efficiently than dogs:
| Carbohydrate (DM) | Evaluation | Metabolic Effect |
|---|
| ≤10% | Ideal | Closest to natural prey composition |
| 10-20% | Good | Generally acceptable |
| 20-35% | Moderate | Requires closer assessment |
| 35-50% | High | May increase insulin resistance risk |
| >50% | Very high | Higher obesity and diabetes risk |
3. Feeding by Life Stage
3.1 Kittens (0-12 months)
Kittens are born at approximately 80-120 g and reach 3-5 kg within 12 months. That rapid growth requires a nutrient-dense formula.
| Parameter | Excellent | Good | Acceptable | Inadequate |
|---|
| Protein (DM) | ≥45% | 38-44% | 30-37% | <30% |
| Fat (DM) | 18-25% | 14-17% | 9-13% | <9% |
| Carbohydrate (DM) | ≤15% | 16-25% | 26-35% | >35% |
| Ca:P Ratio | 1.1-1.3:1 | 1.0-1.5:1 | 0.9-2.0:1 | <0.9 or >2.0 |
3.2 Adult Cats (1-7 years)
| Parameter | Excellent | Good | Acceptable | Inadequate |
|---|
| Protein (DM) | ≥40% | 35-39% | 26-34% | <26% |
| Fat (DM) | 15-22% | 12-14% | 9-11% | <9% |
| Carbohydrate (DM) | ≤20% | 21-30% | 31-40% | >40% |
| Fiber (DM) | 2-5% | 1-2% | <1% or >7% | - |
3.3 Neutered Cats
After neutering, metabolic rate commonly falls by 20-25% while appetite often increases. The risk of obesity rises sharply.
| Parameter | Excellent | Good | Acceptable | Inadequate |
|---|
| Protein (DM) | ≥42% | 38-41% | 30-37% | <30% |
| Fat (DM) | 10-15% | 8-9% or 16-18% | 6-7% or 19-22% | <6% or >22% |
| Carbohydrate (DM) | ≤20% | 21-28% | 29-35% | >35% |
| Fiber (DM) | 4-8% | 3-4% | 2-3% | <2% |
| L-carnitine | Present | - | Absent | - |
✓ Choosing food for a neutered cat: Prefer formulas with high protein for lean mass support, lower fat for energy control, and higher fiber for satiety. L-carnitine is a useful added feature when present.
3.4 Senior Cats (7+ years)
- Protein: 40-50% DM to help preserve muscle mass
- Phosphorus: <1.0% DM for renal support
- Omega-3: Increased for anti-inflammatory support
- Antioxidants: Vitamin E and selenium
4. Therapeutic Diets
4.1 Urinary Diets
Lower urinary tract disease is common in cats, and diet is a key part of management.
| Condition | Target Urine pH | Magnesium | Phosphorus |
|---|
| Struvite dissolution | 6.0-6.3 | <0.08% DM | <0.8% DM |
| Oxalate prevention | 6.5-7.0 | Normal | Normal |
4.2 Renal Diets
| CKD Stage | Protein (DM) | Phosphorus (DM) | Omega-3 |
|---|
| Stage 1-2 | 28-32% | <0.7% | Increased |
| Stage 3 | 26-30% | <0.5% | High |
| Stage 4 | 24-28% | <0.4% | High |
⚠️ Important: Renal diets should not simply be “low-protein.” They should provide controlled amounts of high-quality protein. Over-restriction may accelerate muscle loss.
4.3 Gastrointestinal Diets
- Digestibility above 90%
- Low fat (10-15% DM)
- Moderate protein (30-35% DM)
- Prebiotic and probiotic support
5. Functional Additives
5.1 Probiotics
| Strain | Documented Effect |
|---|
| Enterococcus faecium | Gut support and diarrhea control |
| Lactobacillus acidophilus | Immune modulation |
| Bifidobacterium animalis | Digestive regulation |
5.2 Prebiotics
- FOS: feeds beneficial gut bacteria
- MOS: may reduce pathogen adhesion and support immune function
- Inulin: prebiotic fiber source
5.3 Omega-3 Fatty Acids
| Source | EPA + DHA | Evaluation |
|---|
| Fish oil | High | Excellent |
| Salmon oil | High | Excellent |
| Flaxseed | ALA only (limited conversion) | Moderate |
6. Undesirable Ingredients
| Ingredient | Concern | VetKriter Effect |
|---|
| “Meat and animal derivatives” | Poor source transparency | -5 points |
| “Animal by-products” | Unclear quality profile | -5 points |
| High corn gluten use | Lower biological value | -3 points |
| BHA/BHT | Potential carcinogenic concern | -3 points |
| Artificial colorants | Unnecessary additive load | -2 points |
| Sugars / sweeteners | Obesity and dental concerns | -4 points |
7. VetKriter Scoring Methodology
| Category | Maximum Score | Assessment Basis |
|---|
| Macronutrient Fit | 40 | Species and life-stage targets based on AAFCO / FEDIAF |
| Ingredient Quality | 30 | Protein source analysis, first ingredient, number of animal-derived inputs |
| Life-Stage Criteria | 15 | Stage-specific components such as taurine and L-carnitine |
| Safety and Purity | 15 | Absence of undesirable or lower-confidence additives |
| TOTAL | 100 | |
Life-Stage Specific Criteria
| Life Stage | Priority Criteria |
|---|
| Kitten | Taurine, DHA, higher protein (35%+ DM), calcium source quality |
| Adult | Taurine, omega source, protein (30%+ DM), prebiotics |
| Neutered | L-carnitine, lower fat, higher fiber, taurine |
| Senior | Taurine, antioxidants, omega-3, adequate protein density |
✓ What makes VetKriter different: Scores are adjusted according to the intended life stage of the formula. Kitten foods are evaluated with kitten criteria; neutered-cat foods are evaluated with neutered-cat criteria.
8. Conclusions and Practical Advice
- Prioritize protein quality: prefer clearly identified animal proteins such as poultry or fish
- Limit excessive carbohydrate: in most cases, aim to stay below 30% DM when possible
- Match the food to life stage: kitten, adult, neutered, and senior formulas are not interchangeable
- Read the ingredient list carefully: the first 3-5 ingredients matter most
- Avoid vague wording: such as “animal derivatives” or unclear by-product language
References
- AAFCO (2023). Official Publication. Association of American Feed Control Officials.
- FEDIAF (2021). Nutritional Guidelines for Complete and Complementary Pet Food for Cats and Dogs.
- NRC (2006). Nutrient Requirements of Dogs and Cats. National Research Council.
- Bradshaw, J.W.S. (2006). The evolutionary basis for the feeding behavior of domestic dogs and cats. The Journal of Nutrition.
- Hewson-Hughes, A.K. et al. (2011). Geometric analysis of macronutrient selection in the adult domestic cat. Journal of Experimental Biology.
- Plantinga, E.A. et al. (2011). Estimation of the dietary nutrient profile of free-roaming feral cats. British Journal of Nutrition.
- Zoran, D.L. (2002). The carnivore connection to nutrition in cats. JAVMA.
In its 2026 recalibration, VetKriter updated several assessment thresholds based on AAFCO and FEDIAF guidance. Penalties for plant-derived protein concentrates such as corn gluten were softened, and carbohydrate tolerance for cats was recalibrated toward the 35-40% range in order to reduce unfair scoring of clinically coherent formulations.