不同产奶水平奶牛的日粮最低蛋白含量预估值
Dietary Protein Requirements, % of Dry Matter | ||||
|---|---|---|---|---|
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Large-Breed Cows | Small-Breed Cows | |||
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Milk production, kg/d | Crude Proteina | Metabolizable Proteinb | Crude Proteina | Metabolizable Proteinb |
18 | — | — | 15.0 | 12.9 |
23 | — | — | 16.4 | 13.1 |
27 | 14.5 | 11.0 | 17.5 | 13.3 |
32 | 15.0 | 11.2 | 18.4 | 13.3 |
36 | 15.8 | 11.5 | 19.0 | 13.3 |
40 | 16.5 | 11.7 | — | — |
45 | 17.3 | 11.9 | — | — |
50 | 17.8 | 12.0 | — | — |
55 | 18.3 | 12.1 | — | — |
This table is intended to provide a general reference for initial evaluations of dairy diets, not a standard against which rations are balanced. Calculation of dietary metabolizable protein concentrations generally requires specialized software. | ||||
aCrude protein requirements were generated by Spartan Dairy version 3.0 (Michigan State University), assuming a mature cow in mid lactation. | ||||
bMetabolizable protein (MP) requirements were generated by NRC Model Software for Nutrient Requirements of Dairy Cattle (National Research Council, 2001). Actual MP will depend upon dietary composition and stage of lactation as milk composition changes. | ||||
