Calculate 2 rations for a mature, pregnant cow weighing 1250lbs... Her dry matte

Question

Calculate 2 rations for a mature, pregnant cow weighing 1250lbs... Her dry matter intake is expected to be between 18.75 and 25lbs. Her CP requirement is 1.47 lbs and her TDN requirement is 10.51 lbs. IN RATION 5..... what if our hay was different, say fescue with 7% CP but still the same TDN?

4-5. Calculate 2 rations for a mature, pregnant cow weighing 1250 lbs. Use the same feeds for ration #4. Her dry matter intake is expected to be between 18.75 and 25 lbs Her CP requirement is 1.47 lbs and her TDN requirement is 10.51 lbs. (In ration 5, What if our hay was different, say fescue with 7% CP (but still the same TDN)?) Ration 5 OM Hay As-Fed DM As-Fed Hay_ Hay Corn SBM Corn- Corn SBM

Explanation / Answer

Let’s assume her DMI was an average of 18.75 and 25 lbs = 22 lbs.

Percent of CP required is 6.68%.

Percent of TDN required is 47.77%.

Using Pearson square method: the preliminary percentage of corn and hay in the ration.

Corn

6.32 ÷ 9.64 = 0.655

(65.5%)

Hay

3.32 ÷ 9.64 = 0.344

(34.4%)

Therefore, the TDN concentration in the mix is:

Hay 0.344 x 55 = 18.94%

Corn 0.655 x 90 = 58.95%

Total TDN = 77.89%

The concentration in the hay/corn mix is 77.89 percent. The feed requires 47.77 percent TDN.

Use the Pearson Square method again using SBM to balance for TDN.

Corn/hay mix

40.23 ÷ 70.35 = 0.571

SBM

30.12 ÷ 70.35 = 0.428

Determine the pounds of dry matter that each feedstuff contributes to the total. Multiply pounds of dry matter required daily by the feed (22 lb) by the percentage for SBM (0.428). Thus, the dry matter component made up by SBM is 22 x 0.428 = 9.42 lb. Subtract this amount from the total dry matter intake (22 lb) to determine how much dry matter will come from the corn/hay mix (22 – 9.42 = 12.58 lb). There should be 12.58 lb of corn/hay mix on a dry matter basis.

For determining the exact amount of corn and hay in the mixture:

Amount of corn in the mixture = 12.58 x 0.655 = 8.24 lb

Amount of hay in the mixture = 12.58 x 0.344 = 4.33 lb

Ration 4:                                                                                Ration 5

DM                             As-Fed                                               DM                  As-Fed

_4.33 lb_ Hay _5.15 lb__                                                   _15.97 lb_ Hay _19.01 lb_

_8.24 lb_ Corn _9.36 lb___                                                _1.54 lb_ Corn _1.75 lb__

__9.42 lb_ SBM 10.47 lb__                                                _4.45 lb_ SBM _4.94 lb_

Corn

6.32 ÷ 9.64 = 0.655

(65.5%)

Hay

3.32 ÷ 9.64 = 0.344

(34.4%)

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