You might find your answer from below libk of CIC:
cic.gc.ca/english/helpcentre/questions-answers-by-topic.asp?top=29
In an Express Entry profile, should I only include the minimum work experience needed to qualify for one of the programs, or should I include more?
To qualify for the broadest range of programs, including the Federal Skilled Worker Program, you should include work experience for the last 10 years. We also need this information for an application for permanent residence, no matter which program you are applying under.
On Top: CIC document check list says:
Document: Employment Records
You must provide proof of work experience for your current job and for each past position you listed. Proof must include a reference letter from your employer and pay stubs, if you have them. The reference letter must:
be an official document printed on company letterhead
include your name, the company’s contact information (address, telephone number and e-mail address), the signature of your immediate
show all positions held while employed at the company
include these details: job title, duties/responsibilities, job status (if current job), the dates you worked for the company, the number of work hours per week and your annual salary plus benefits.
You must scan all documents for this period of employment and save them as one file. (You must create a separate file for each period of employment.)
There is a similar post here and you might draw inference from this site.
canadavisa.com/canada-immigration-discussion-board/employer-will-not-provide-experience-letter-t181212.15.html
sumitbhutanigwl said:
Hi ,
I would like to inquire about Job Reference letters. I have worked in 4 organisations till now. 1st with 6 months of experience, 2nd with 2.11 years, 3rd with 4 months and 4th I am currently working with around 1 year experience.
Do I need reference letters for all 4. Would an affidavit/notarized document work in case of my 1st and 3rd company, where experience is less than 1 year?
Thanks in advance.
Sumit Bhutani