The formulas to calculate manure production for horses are:

1. For Breeding:

\[ W_m = 13.50 \cdot N_a \cdot N_d \]

2. For Work:

\[ W_m = 7.75 \cdot N_a \cdot N_d \]

Where:

• \(W_m\) is the weight of manure produced in kilograms (kg).
• \(N_a\) is the number of animals.
• \(N_d\) is the number of days.