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TDN question

terra8186

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I am developing a feed program and have been researching the TDN and CP values for my feed options.

I have all of the TDN and CP values but now I don't know what to do with them. I am hobby feeding out cattle for beef. I purchase calves at 350 pounds and process them at 1,100 pounds. I don't understand the relationship between TDN, CP, the weight of the calf, and the total feed intake.

I am guessing you want the total feed intake to weight of the calf at 2%. If I assume a 2% feed intake what should TDN and CP be? Is there a formula?
 

msscamp

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terra8186":182aykw6 said:
I have all of the TDN and CP values but now I don't know what to do with them. I am hobby feeding out cattle for beef. I purchase calves at 350 pounds and process them at 1,100 pounds. I don't understand the relationship between TDN, CP, the weight of the calf, and the total feed intake.

Ok, I'll take a stab at this. I am no expert but, as I understand it, the TDN is the amount of nutrition that an animal can digest and readily utilize. If your TDN is 60%, and your CP is 20%, then 12% of the crude protein is readily available to be converted into maintenance/weight gain by the animal. The higher the TDN, the better quality the hay is, and more of the feed is converted to pounds. The higher quality the hay, the less you will have to feed, as well. If your TDN is 20%, then much less of the hay is able to be converted, and you will need to feed more hay in order to put pounds on the animal. Again, I am not an expert. This is just my understanding, and it could be wrong.

I am guessing you want the total feed intake to weight of the calf at 2%. If I assume a 2% feed intake what should TDN and CP be? Is there a formula?

2-3% of total body weight is the norm, but that is going to vary from calf to calf due to appetite, easy keeper vs hard keeper, energy levels, skittishness, etc. There is no hard and fast/one size fits all 'formula' for feeding, you will just have to start with the basic 2-3% of body weight, watch how each animal does, and adjust as needed. Whether or not you are feeding grain or other supplements will also have an impact on how much hay is consumed/needed.
 

hayray

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TDN values are better used for balancing cow rations. For feeders better to use Net energy and CP values. Feed high energy concentrate (corn) guessed at 8% protein and at 80% of total dry mater intake and feed hay to match at 20% Dry matter intake and feed to match 3% of body weight of dry matter intake/day. You can test your hay or make assumptions of hay CP % and then from there see if you need to add any protein to bring overall dietary protein up to 12% of diet. Often while feeding a grass mix hay you can add a half pound/head of protein per day to make up for it -- for example - 1 pound per head per day of soybean meal at 48% protein gives you an extra half pound per day. MSU is having a cattle feeding program tonight up at the pavillion on campus at 6:30.
 

terra8186

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<MSU is having a cattle feeding program tonight up at the pavillion on campus at 6:30.>

I probably would have went had known earlier.

What I learned from the previous posts is feed at 2-3% body weight at a 12% CP. That is what I needed to know.

Thanks
Steve
 

donnaIL

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This link has a beef cattle production booklet that specifically addresses TDN & CP (with formulas).

http://www.aces.uiuc.edu/~vista/abstracts/abeef.html

Some of it is specific to forages in IL, but I have found it to be quite helpful in planning (how much hay will I need senerio, how much to feed etc). There is a chart in there that gives you the TDN and CP requirement by weight and how much you want them to gain. With the price of corn so high this last year, I am trying to grow the calves good and then finish them in a shorter time frame, with less cost.
 

hayray

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Donna, that is a good booklet, I just down loaded it. I have been at the Illini Beef team site a couple of years ago and got some good info.
 

donnaIL

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I should have added that there is an error (I believe so anyway) on page 3, table 1-2...the TDN and CP figures are reversed (under the wrong column). If you punch in the wrong #'s you will be saying ??what??.

One thing this book has shown me, is our animals get more than enough TDN and CP in their daily diet. Also we use to just pour the corn to them (when it was cheap), now I am looking more at what they need, animal performance, etc...

The extension office had this booklet at a seminar we attended, they were selling it...glad I had found it online for free before then.
 

TJ

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Guys your missing the boat, very little hay is needed to finish cattle, corn and by-products will get the job done, min 13% protein and look at NEG,
We can put on 3.5 #'s a day easy, fed them like swine
 

msscamp

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TJ":319k2mhn said:
Guys your missing the boat, very little hay is needed to finish cattle, corn and by-products will get the job done, min 13% protein and look at NEG,
We can put on 3.5 #'s a day easy, fed them like swine

Perhaps I missed something, but where did the original poster state that he was finishing cattle? Based on his post, I am thinking he is wanting to develop a ration that will enable his calves to grow out and develop properly - again, maybe I missed something.
 

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