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COW PEAK MILK CALCULATOR
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INSTRUCTIONS
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This calculator is designed to compute the peak milk production of a cow herd based on actual weaning weight of steer calves, age at weaning, and forage TDN.
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Go to the tab labeled 'Peak Milk'
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Cells highlighted in blue require input.
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Cells highlighted in orange contain the computations.
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It is best if you have actual values to enter into the spreadsheet, but if you do not then follow these general guidelines.
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If actual birth weight of calves is not known, a reasonable estimate of average steer calf birth weight is between 70 and 90 lb with larger breed types having heavier birth weights.
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If actual slaught body weight of previous calves is not known, a reasonable estimate of calf body weight at slaughter is between 1200 and 1400 lb. Larger, later maturing breed types would have heavier weights at slaughter.
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It is recommend that samples of forage be collected and analyzed for each month since calving since forage TDN values are extremely variable from year to year and ranch to ranch. It is very important that forage samples represent what the calf is eating as much as possible. However if forage TDN values are not known, reasonable estimates for forage TDN can be provided by your local county livestock agent. Be sure to input the correct forage values for each month since calving, not as months of the year.
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If actual birth date of calves is not known in order to calculate age at weaning, use the approximate date when 50% of the cows have calved or mid-point of your calving season. Remember, more cows likely calve in first half of the calving season than the last half so the average birth date is slightly before the mid-point of the calving season.
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It is recommended that energy content of milk be computed from analysis of milk samples from a few cows. Digestible energy of milk (Mcal/kg) can be calculated with the formula = (0.057 x milk protein%) + (0.092 x milk fat%) + (0.0395 x milk lactose %) then multiplied by 0.95. Milk protein, fat, and lactose % need to be on a dry matter basis for use in this formula. If analysis of milk samples is not available, then values between 5.75 and 6.45 are reasonable estimates of digestible energy of milk.
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Once all the necessary information is entered into the blue cells, then click the 'CALCULATE' button and the estimated peak milk of the cow herd will be computed in the cell labeled 'Calculated Cow Peak Milk, lb'. Macros must be enabled for the 'CALCULATE' button to work.
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