RUFAS.routines.animal.life_cycle.lactation_curve module#

RUFAS.routines.animal.life_cycle.lactation_curve.MILKING_FREQUENCY_THRESHOLD = 2.5#: Constants used to scale the adjustments for Wood’s m and n parameters, respectively, before using them to the adjust parameters.

RUFAS.routines.animal.life_cycle.lactation_curve.N_ADJUSTMENT_SCALING_FACTOR = 0.0001#: If user’s input for parity 1, 2, and 3+ fractions of the milking herd are invalid (i.e. do not sum to 1), then the below defaults will be used. Note that these defaults are ONLY used to adjust the lactation curve parameters, they are not used at all to determine herd structure. These numbers are from Li et al, 2023.

References#

[1]
Li, M., K. F. Reed, and V. E. Cabrera. “A time series analysis of milk productivity in US dairy states.” Journal

of Dairy Science 106.9 (2023): 6232-6248.

RUFAS.routines.animal.life_cycle.lactation_curve.PARITY_3_DEFAULT_FRACTION_OF_MILKING_COWS = 0.333#: These constants regulate the range and precision used to fit Wood’s l lactation parameter to estimated 305 day milk yields.

RUFAS.routines.animal.life_cycle.lactation_curve.STEP_SIZE = 0.01#: Defines the accepted error tolerance when checking that fractions of parity 1, 2 and 3+ milking cows sum to 1.0.

class RUFAS.routines.animal.life_cycle.lactation_curve.LactationCurve(time: RufasTime)#

Bases: object

Manages Wood’s lactation curve parameters l, m, and n as they are used by the rest of the Animal module.

Parameters#

timeRufasTime: RufasTime instance that manages time in the simulation.

Attributes#

omOutputManager: The OutputManager for this module to use.
parity_1_parametersdict[str, float]: Contains the adjusted l, m, and n parameters for parity 1 cows.
parity_2_parametersdict[str, float]: Contains the adjusted l, m, and n parameters for parity 2 cows.
parity_3_parametersdict[str, float]: Contains the adjusted l, m, and n parameters for parity 3+ cows.
parity_to_parameter_mappingdict[int, dict[str, float]]: Maps the parity (1, 2, and 3+) to the associated sets of l, m and n parameters.
parity_to_std_dev_mappingdict[int, dict[str, float]]: Maps parities (1, 2, and 3+) to the standard devations of Wood’s l, m, and n parameters.

__init__(time: RufasTime) → None#

_get_year_adjustments(year_adjustment_values: dict[str, dict[str, float]], time: RufasTime) → dict[str, float]#: Retrieves the appropriate adjustment values based on the end year of the simulation.

_get_region_adjustments(region_adjustment_values: dict[str, dict[str, float]], region_mapping: dict[str, str], fips_code: int) → dict[str, float]#: Retrieves the appropriate adjustment values for the region being simulated.

_get_milking_frequency_adjustments(milking_frequency_adjustments: dict[str, dict[str, float]], milking_frequency: float) → dict[str, float]#: Retrieves the lactation curve adjustment values for the milking frequency of cows in the simulation.

_calculate_adjusted_wood_parameters(l_param: float, m_param: float, n_param: float, adjustments: list[dict[str, float]]) → dict[str, float]#

Computes Wood’s Lactation Curve parameters adjusted for different factors.

Parameters#

l_paramfloat: Base value for Wood’s l parameter (unitless).
m_paramfloat: Base value for Wood’s m parameter (unitless).
n_paramfloat: Base value for Wood’s n parameter (unitless).
adjustmentslist[dict[str, float]]: List of adjustment sets, where each dictionary in the list represents the adjustments for a single factor (region, parity, etc.) and contains the keys “l”, “m”, and “n”.

Returns#

dict[str, float]: Dictionary containing the adjusted Wood l, m, and n parameters.

get_milk_yield_values_wood_curve(day_of_milk: int, l_param: float, m_param: float, n_param: float) → float#

Calculates the milk yield on the given day using Wood’s lactation curve.

Parameters#

day_of_milkint: Days into milk of the cow.
l_param: float: Wood’s lactation curve parameter l.
m_param: float: Wood’s lactation curve parameter m.
n_param: float: Wood’s lactation curve parameter n.

Returns#

numpy.float64: Milk yield on the provided day (kg).

References#

Li, M., et al. “Investigating the effect of temporal, geographic, and management factors on US Holstein lactation curve parameters.” Journal of Dairy Science 105.9 (2022): 7525-7538.

calc_305_day_milk_yield(l_param: float, m_param: float, n_param: float) → float#

Calculates the total milk yield from day 1 to day 305 of the lactation.

Parameters#

l_param: float: Wood’s lactation curve parameter l.
m_param: float: Wood’s lactation curve parameter m.
n_param: float: Wood’s lactation curve parameter n.

Returns#

float: 305 day milk yield for a cow with the given lactation curve (kg).

get_wood_parameters(parity: int) → dict[str, float]#

Adjusts the default lactation curve parameters based on farm-specific attributes.

Parameters#

parityint: The number of calves that a cow has had.

Returns#

dict[str, float]: Wood’s parameters l, m, and n for the specified parity.

_adjust_lactation_curve_to_milk_yield(animal_inputs: dict[str, Any], lactation_curve_inputs: dict[str, dict[str, Any]]) → None#: Adjust the lactation parameters using predicted milk yields for the different parities of cows on the farm.

_estimate_305_day_milk_yield_by_parity(annual_milk_yield: float, num_milking_cows: int, parity_1_frac: float, parity_2_frac: float, parity_3_frac: float, parity_2_milk_yield_adjustment: float, parity_3_milk_yield_adjustment: float) → dict[str, float]#

Calculates the 305-day milk yield for each lactation group based on total farm milk production.

Parameters#

annual_milk_yieldfloat: Annual milk yield of the farm (kg).
num_milking_cowsint: Number of milking cows on the farm.
parity_1_fracfloat: Fraction of cows on the farm that have a parity of 1.
parity_2_fracfloat: Fraction of cows on the farm that have a parity of 2.
parity_3_fracfloat: Fraction of cows on the farm that have a parity of 3 or more.
parity_2_milk_yield_adjustmentfloat: Factor used to adjust for parity 2 cows (unitless).
parity_3_milk_yield_adjustmentfloat: Factor used to adjust for parity 3 cows (unitless).

Returns#

dict[str, float]: Mapping of the parity (1, 2, 3+) to the estimated 305 day milk production of an individual cow of that parity (kg).

_fit_wood_l_param_to_milk_yield(l_param: float, m_param: float, n_param: float, milk_yield: float) → float#

Modifies Wood’s l parameter to best fit a given 305 day milk yield.

Parameters#

l_paramfloat: Wood’s l lactation curve parameter.
m_paramfloat: Wood’s m lactation curve parameter.
n_paramfloat: Wood’s n lactation curve parameter.
milk_yieldfloat: 305 day milk yield that Wood’s l parameter will be fitted to (kg).

Returns#

float: Wood’s l parameter adjusted to best fit the given milk yield.