Not necessary, if you have it you can add them but don't worry, if the letter have all the required information there is no need of any other document.
Thanks all. I worked from 207 to 2012 in India and I really doubt how many pay slips I have from that time maybe 2-3 out of 60, then in 2012 I came to US to do MBA and from 2014 I am working in my current job and have all payslips. I have asked experience letters that only will mention duration., designation and job description. I can show all my last 3 years salary slips in current job but not from my other pre-MBA employer. Is it OK? I will explain in LOE.