Antibiotics added to livestock feed have been found to increase their growth rate, reduce incidence of infection, reduces mortality and improve feed conversion ratio or feed efficiency.
Lipid bilayer model was proposed for its structure but it was modified and new structure is according to fluid mosaic model. Plasma membrane is selectively permible as it selects small molecules like lipid etc (composition is also of lipid and as solubility principle like dissolve like) so large and charged molecules like plasma and ion can't pass through it. Lipid are in form of layer so at the chain when ever other phosphate group attach the place conjugate molecule (phospholipid ) formed
I believe the primary structure will be preserved. The secondary level of proteins is defined by patterns of hydrogen bonds between the main chain peptide groups. Therefore distorting the Hydrogen bonds disrupts the secondary structures. The primary structure on the other hand is not affected by disruption of the hydrogen bond since these structures refers to the sequences of amino acids in the polypeptide chains that are joined by the peptide bonds.