It is better the enter the theft on Schedule F. If you enter the theft directly onto form 4684 through the casualty and theft section, you will be subject to the $100 and 10% of AGI limitation. Going through Schedule F will not limit your deduction.

If you already use Schedule F and the stolen animals were listed as assets Schedule F, all you have to do is go through the steps to show the assets as stolen, and it will automatically deduct amount you have not depreciated. TurboTax should report this for you on Form 4684, Part II.

In the asset section of your farm business section, on the screen "Tell Us More About This Farm Asset", check the box by The item was sold, retired, stolen..... continue through the screens answering the questions. 

If you never added the animals to Schedule F, you should add them first, even if the date of purchase was prior to 2017 and also follow the instructions above to enter them as stolen.