Breeding Guide
Realistic Livestock RM replaces the base game's automatic reproduction with a realistic system requiring males and females, age requirements, health thresholds, and species-specific gestation periods. This guide covers everything you need to know about breeding.
Note: This documentation was generated with AI assistance and may contain inaccuracies. If you spot an error, please open an issue.
Requirements for Breeding
For reproduction to occur, ALL of the following must be true:
- Male and female of the same species in the same pen (or artificial insemination)
- Female has reached minimum breeding age
- Male has not exceeded maximum breeding age
- Female is not already pregnant
- Female health is 75% or above
- Female is not the daughter of that specific male (inbreeding prevention)
Breeding Ages & Gestation
| Species | Female Breeds From | Male Breeds From | Male Breeds Until | Gestation | Female Fertility Ends |
|---|---|---|---|---|---|
| Cattle | 12 months | 12 months | 132 months (11 yr) | 10 months | 132 months (11 yr) |
| Pigs | 6 months | 8 months | 48 months (4 yr) | 4 months | 96 months (8 yr) |
| Sheep | 8 months | 5 months | 72 months (6 yr) | 5 months | 120 months (10 yr) |
| Goats | 16 months | 5 months | 72 months (6 yr) | 5 months | 120 months (10 yr) |
| Horses | 22 months | 36 months | 300 months (25 yr) | 11 months | 264 months (22 yr) |
| Chickens | 6 months | 6 months | No limit | 2 months | Declines with age |
Critical insight: Males retire from breeding much earlier than females in some species! Boars stop at 4 years while sows breed until 8. Rams stop at 6 years while ewes breed until 10. Plan male replacements early.
Breed Restrictions
Most males can breed with any female of their species, with two important exceptions:
| Male | Can Breed With |
|---|---|
| Water Buffalo Bull | Water Buffalo cows only |
| Ram Goat | Goats only |
| Any other Bull | Any cow breed (except Water Buffalo) |
| Any other Ram | Any sheep breed (except Goats) |
| All Boars | Any pig breed |
| All Stallions | Any horse colour |
| All Roosters | Any hen |
Cross-breeding between different breeds of the same species is allowed (e.g., Angus bull × Holstein cow), except for breed-locked types.
Offspring per Birth
Cattle
Cattle usually produce single calves. Twins and triplets are rare.
| Cow Age | No Birth | 1 Calf | Twins | Triplets |
|---|---|---|---|---|
| 12–28 mo | Moderate | Most likely | Rare | Very rare |
| 29–48 mo (prime) | Low | Most likely | Rare | Very rare |
| 49–84 mo | Increasing | Most likely | Rare | Very rare |
| 85–132 mo (old) | Very common | Less likely | Very rare | Extremely rare |
Pigs
Pigs produce the largest litters. Healthy sows at prime age almost always deliver.
| Sow Age | Chance of No Birth | Typical Litter | Large Litter |
|---|---|---|---|
| 6–12 mo (young) | Low | 11–13 piglets | 14–16 possible |
| 13–36 mo (prime) | Very low | 11–13 piglets | 14–16 possible |
| 37–60 mo | Low–moderate | 11–13 piglets | 14–16 possible |
| 61–80 mo | Moderate | 11–13 piglets | Fewer |
| 81–96 mo (old) | High | Small litters | Rare |
Most pig litters are 11–13 piglets. Low health significantly reduces litter size.
Sheep & Goats
Sheep and goats have high twin rates at prime age. First-time mothers usually have singles.
| Ewe/Doe Age | Singles | Twins | Triplets |
|---|---|---|---|
| First-time mother | Most likely | Uncommon | Rare |
| 18–36 mo | Common | Common | Rare |
| 36–72 mo (prime) | Less common | Most likely | Uncommon |
| 72–120 mo (old) | Uncommon | Most common | Rare |
At prime age, twins are more common than singles! Goats follow the same pattern but start breeding later (16 months vs 8 months for sheep).
Horses
Horses almost always produce a single foal.
| Outcome | Likelihood |
|---|---|
| 1 foal | Almost always |
| Twins | Rare |
| Triplets | Very rare |
Horse fertility declines gradually with age through to 264 months.
Chickens
Chickens have large but unreliable hatches. The chance of no offspring is always significant.
| Hen Age | No Hatch | Small Brood (1–5) | Typical Brood (5–7) | Large Brood (7–12) |
|---|---|---|---|---|
| 6–12 mo | Common | Uncommon | Most likely | Possible |
| 12–24 mo | Common | Uncommon | Most likely | Possible |
| 24–48 mo | Frequent | Uncommon | Less likely | Rare |
| 48–84 mo | Very common | Rare | Rare | Very rare |
| 84+ mo | Almost always | Very rare | Very rare | - |
Unlike other animals, hens never die during hatching.
Lactation
Cows and goats enter a lactation period after giving birth. This has major effects on both production and consumption.
| Parameter | Value |
|---|---|
| Duration | 10 months after birth |
| Milk production | Only during lactation (zero otherwise) |
| Food consumption | Noticeably higher during lactation |
| Water consumption | Considerably higher during lactation |
| Sell price | Small bonus while lactating |
Lactation Phase Curve
Milk output varies within the lactation period:
| Months Since Birth | Milk Output |
|---|---|
| 0–1 | Ramping up (below full potential) |
| 2–3 | Peak production |
| 4–9 | Gradually declining |
| 10+ | Lactation ends (zero milk) |
Peak milk production occurs around month 2–3 after birth. See the cattle and sheep factsheets for specific breed output ranges.
Chart shows the typical shape of the lactation curve. Actual litres depend on breed and genetics - see the cattle factsheet for specific ranges.
Pregnancy Complications
Breeding is not without risk. Low health significantly increases complications:
| Parent Health | Risk Level |
|---|---|
| 90%+ | Very low risk of complications |
| 75–90% | Low risk |
| 60–75% | Moderate risk, fewer offspring |
| Below 60% | High risk, mother may die during birth |
If the mother dies during birth, offspring may still survive. Low health also reduces the chance of multiple offspring.
Pen Capacity
If a pen is at maximum capacity when offspring are born, excess newborns are automatically sold. Make sure your pens have room for new arrivals, especially:
- Pig pens (litters of 11–16)
- Sheep pens at prime age (frequent twins)
- Any pen during peak breeding season
Artificial Insemination
If you don't want to keep males, artificial insemination (AI) is available through the livestock menu. Press I on a female animal to open the insemination dialog.
- Breeds your female without needing a physical male in the pen
- Uses an AI animal pool (can be refreshed in settings)
- Same breed restrictions apply (Water Buffalo and Goats need breed-specific AI)
- Same health and age requirements apply
- The insemination button is automatically disabled when the female is ineligible (pregnant, too young, or recovering from birth)
Multiplayer note: Semen dewars (AI canisters) cannot be physically picked up by clients. The dewar interaction menu works, but moving dewars only works in singleplayer or as the host.
Breeding Calendar
Plan your breeding based on gestation periods:
| Species | Breed | Birth | Next Possible Breeding |
|---|---|---|---|
| Cattle | Month 0 | Month 10 | ~Month 12 (after lactation) |
| Pigs | Month 0 | Month 4 | ~Month 5 |
| Sheep | Month 0 | Month 5 | ~Month 6 |
| Horses | Month 0 | Month 11 | ~Month 12 |
| Chickens | Month 0 | Month 2 | ~Month 3 |
Cows have the longest cycle - roughly one calf per year at best. Pigs can produce 2–3 litters per year, making them the fastest-reproducing large animal.
Tips
-
Track male ages. The #1 surprise is boars stopping at 4 years. Set up reminders or check your boar ages regularly.
-
Breed for genetics. Offspring inherit from parents. Pair your best animals and sell poor-genetics offspring for a steady improvement each generation.
-
Keep health above 75%. Below 75%, breeding fails entirely. Below 60%, the mother risks death. Good food, water, straw, and medical treatment are essential.
-
Budget for lactation costs. Lactating cows eat noticeably more food and considerably more water. Plan your feed budget for the 10-month lactation window.
-
Use pen capacity wisely. A pig sow can produce 13 piglets at once. If your pen only has 5 spaces, 8 piglets get auto-sold at newborn prices. Expand pens before breeding season.