Whole-herd optimization with the Cornell Net Carbohydrate and Protein System. I. Predicting feed biological values for diet optimization with linear programming
Lo. Tedeschi et al., Whole-herd optimization with the Cornell Net Carbohydrate and Protein System. I. Predicting feed biological values for diet optimization with linear programming, J DAIRY SCI, 83(9), 2000, pp. 2139-2148
We developed a diet optimizer for least-cost diet formulation with the Corn
ell Net Carbohydrate and Protein System (CNCPS) using linear programming. T
he CNCPS model is intrinsically nonlinear, and feed biological values vary
with animal and feed characteristics. To allow linear diet optimization, we
first used the CNCPS model to generate biological values to characterize t
he energy and protein content of each feed for the specific group for which
the diet was being formulated. The biological values used were metabolizab
le energy (Mcal/kg), metabolizable protein [(% dry matter (DM)], passage ra
te (%/h), bacteria yield efficiencies (g/g), and degradation rate of the ca
rbohydrate B2 fraction (%/h). In addition, the ruminal balances for nitroge
n and peptides were included in the optimizer to optimize ruminal degradati
on of fiber. The objective function was to minimize diet cost subject to an
imal requirement and feed availability constraints. The animal constraints
were set by requirements for DM intake (kg/d), metabolizable energy (Mcal/k
g), metabolizable protein (%DM), and effective neutral detergent fiber (%DM
) for a given level of production. Data from a dairy farm were used to eval
uate this linear diet optimizer. Across all classes of dairy cattle, the CN
CPS 4.0 model typically obtained a solution in less than six iterations tha
t met the requirements with nearly 100% accuracy. We conclude this linear o
ptimizer can be used to accurately formulate least-cost diets with the CNCP
S model.