Two numbers run the first 6 weeks of lactation: kilocalories per kilogram per day, and millilitres of water per kilogram per day. Everything else on the sheet, from body condition to litter size, exists to move those 2 numbers up or down. The ranges below are the ones most nutrition references use; they are targets to compare a real cat against, not a prescription to hit exactly.
This page covers demand ranges and records only. Whether a queen should be bred at all is a separate decision, and any clinical problem during lactation belongs with a vet.
2 numbers, and the arithmetic behind them
Resting energy for an adult cat is about 70 x (body weight in kg) raised to 0.75, which puts a 4 kg queen near 200-220 kcal a day, or 50-55 kcal/kg. Maintenance for a quiet indoor adult is usually quoted at 60-70 kcal/kg a day. Lactation multiplies that: about 1.4-1.5x in week 1, 1.9-2.3x in week 2-3, 2.2-2.9x at the week 3-4 peak, and back toward 1.5x by week 6-8.
Water tracks the energy. Maintenance intake is 60 ml/kg a day; lactation pushes it to 95-120 ml/kg at peak, because milk output in a litter of 4-6 runs 100-200 ml a day. A queen at 4 kg therefore moves from about 240 ml a day to 380-480 ml a day in 3 weeks.
The 6-week curve, in 1 table
| Week | kcal/kg/day | Water ml/kg/day | Weight vs pre-pregnancy |
|---|---|---|---|
| 0-1 | 90-105 | 70-85 | -5 to -10% at birth |
| 1-2 | 105-130 | 80-95 | flat |
| 2-3 | 130-160 | 90-105 | 0 to +2% |
| 3-4 | 150-200 | 95-120 | flat at the peak |
| 4-6 | 120-160 | 90-110 | -1 to -2% a week |
| 6-8 | 90-110 | 70-90 | -2 to -3% a week |
Read the table as 2 curves that peak together. Between week 0-1 and week 3-4, energy demand roughly doubles while water demand rises by about 40%. If a queen holds intake flat across those 4 weeks she is not eating to the curve, and the weight column is where that shows up first.
Why week 3-4 is the peak
Kitten weight roughly doubles in the first 3 weeks, and demand peaks when the litter is 3-4 weeks old and each kitten is gaining 10-15 g a day. Five kittens at 15 g a day is 75 g of new kitten daily, and with milk at roughly 1.3 kcal/ml the queen is exporting well over 100 kcal a day in milk alone. That is the arithmetic reason the peak lands at week 3-4 rather than at birth, which is what most owners expect.
Energy density decides whether the curve is reachable
Dry food runs about 4.0-4.5 kcal/g and wet food about 0.9-1.2 kcal/g, so the same 200 kcal is 45-50 g of dry or 170-220 g of wet. A queen at 150-200 kcal/kg on a 4 kg frame needs 600-800 kcal at peak, which is 140-200 g of dry food a day. If she cannot physically eat that volume, the answer is a denser food rather than a longer feeding window, and that choice belongs with the vet.
Water: the number nobody records
Water is the field that goes blank on most sheets, and the first to move when a queen is unwell. Measure by difference: fill the bowl to a marked line at 08:00 and read the drop at 08:00 the next day, in ml. A bowl that goes down 300 ml in 24 hours in a 4 kg queen at week 3 is on target; 150 ml is half the expected intake and worth a note.
Wet food carries 75-80% water, so a queen on wet food drinks visibly less and is still fine. Record the food type in the same row as the water number, otherwise the 2 columns contradict each other and neither gets read.
3 lines a day beat 1 estimate a week
Line 1, food offered in grams. Line 2, food left in grams. Line 3, water drop in ml. Subtract and you have intake, in under 60 seconds at the same hour daily. Weigh the queen weekly on the same scale and score body condition every 30 days on the 1-9 scale, with 4-5 as the target through lactation.
Two flags are worth writing down before they become a conversation: intake falling 25% for 48 hours, and weight dropping 5% in a week after week 2. Both are numbers, not impressions, and both are easier to act on when the 5 preceding days are on the same page.
Body condition is the correction, not the goal
A queen at 3/9 at week 3 is drawing on reserves and the energy target should be reviewed with a vet. A queen at 7/9 at week 6 is carrying the litter's demand forward and the same review applies. The useful rule is narrow: hold 4-5, change 1 variable at a time, and give any change 14 days before judging it, because intake data over 3 days is noise.
When intake falls, and what it means
A queen off food for 24 hours during lactation is a veterinary problem rather than a menu problem, and the same is true of water intake halving overnight, or a queen that stops eating while still producing milk. Take the sheet with you: 5 days of grams and millilitres answers in 2 minutes what a description cannot answer at all.
If litter size is the variable you are trying to model, the weight band of the breed sets the frame before any kcal number means anything, and the breed quiz gives a 2-3 candidate shortlist. The worked example runs the same arithmetic on a 3.5 kg queen, and the postpartum recovery timeline covers the checks that sit outside nutrition.
Do this week
- Weigh the queen today and write the number in the header.
- Mark the water bowl at 08:00 and read it at 08:00 tomorrow.
- Start 3 lines a day: offered g, left g, water ml.
- Note the food type and its kcal/g on the same row.
- Put week 3-4 in the calendar as the review point for the peak.
The whole system is 2 numbers and 3 lines a day. Energy demand doubles across 4 weeks and water rises about 40%; a queen that keeps up shows it in the weight column before she shows it any other way.
Frequently asked
How many calories does a lactating queen need?
About 1.4-1.5 times maintenance in week 1, rising to 1.9-2.3 times in week 2-3 and 2.2-2.9 times at the week 3-4 peak. With maintenance at 60-70 kcal/kg a day, that is roughly 90-105 kcal/kg in week 1 and 150-200 kcal/kg at the peak, then back toward 1.5 times by week 6-8.
How much water should a nursing cat drink?
Maintenance is about 60 ml/kg a day. Lactation pushes it to 70-85 ml/kg in week 1 and 95-120 ml/kg at the week 3-4 peak, because milk output in a litter of 4-6 runs 100-200 ml a day. A 4 kg queen therefore moves from about 240 ml to 380-480 ml a day within 3 weeks.
What intake change means a vet visit?
Food intake falling 25% for 48 hours, weight dropping 5% within a week after week 2, water intake halving overnight, or a queen off food for 24 hours while still producing milk. Bring 5 days of grams and millilitres rather than a description, since the trend answers in 2 minutes what memory cannot.