I've actually found that Baytril antibiotic is the worst for upsetting the gut bacteria and they only recommend it is given for up to 10 days due to the fact it causes crop problems.
The Tylan 200 is recommenced by most vets around here for birds as it doesn't upset the gut bacteria as much, they also recommend that the withdrawal time on be 7 days
TYLAN
SOLUBLE
Elanco
Tylosin Tartrate
Soluble
For Use in
Chickens, Turkeys, and Swine
Equivalent to 100 g tylosin base
An Antibiotic
NADA #13-076, Approved by FDA
Indications
Chickens: As an aid in the treatment of chronic respiratory disease (CRD) caused by Mycoplasma gallisepticum sensitive to tylosin in broiler and replacement chickens. For the control of chronic respiratory disease (CRD) caused by Mycoplasma gallisepticum sensitive to tylosin at time of vaccination or other stress in chickens. For the control of chronic respiratory disease (CRD) caused by Mycoplasma synoviae sensitive to tylosin in broiler chickens.
Chickens should be treated for three days; however, treatment may be administered for one to five days depending upon severity of infection. Treated chickens must consume enough medicated water to provide 50 mg per pound of body weight per day. Only medicated water should be available to the birds.
WARNING:
Chickens must not be slaughtered for food within 24 hours after treatment. Turkeys must not be slaughtered for food within five days after treatment. Swine must not be slaughtered for food within 48 hours after treatment. Do not use in layers
Residue in eggs while taking this product:
Tolerances are established for residues of tylosin in edible products of animals as follows:
a. Chickens and turkeys: 0.2 part per million (negligible residue) in uncooked fat, muscle, liver, and kidney.
b. Cattle: 0.2 part per million (negligible residue) in uncooked fat, muscle, liver, and kidney.
c. Swine: 0.2 part per million (negligible residue) in uncooked fat, muscle, liver, and kidney.