Is there an efficient way to give a large class of students feedback about their assignments? I am the course lecturer of a large undergraduate course
with about 700 students in the course.
One of the challenges of teaching such a large course
is grading the assignments and giving students feedback.

Here is some information about the grading process:


The students submit their assignments electronically,
using a learning management system
The graders grade the assignment by filling in a spread


I would like to give the students two types of feedback:


Students would receive their scores for each question part,
e.g., 1A: 10/10, 1B: 5/5, 1C: 2/5, etc.
For each question part where marks were lost,
students would receive some comments about why they lost marks,
e.g., wrong units in 1B, did not round to an integer in 2A, etc.


Is there an efficient way to give a large class of students
such feedback about their assignments?

I considered asking the TA to email each student
their score for each question part and the mistakes that they made.
However, this seemed to me to be very time consuming and impractical.

Response to questions in comments

Question:
How many students does each TA handle?
Is the group of a particular TA consistent throughout the course?
That is, does the TA handle the same students for the course?
Are the "graders" also the TAs?

Answer:
We have about 5 PhD students who take the role of graders,
i.e., their job is only to do grading.
We also have 1 TA who is a recently graduated BSc student,
whose job is primarily to do admin work,
although she also helps out with a little bit of grading.

Question:
What is the learning management system?
Do you know all of the available features on this system?

Answer:
We are using the Canvas learning management system.
It is possible to give comments for each student's assignment;
however, to the best of my knowledge,
this has to be done one assignment at a time,
which means that giving feedback this way would be fairly time-consuming.
If the class has 700 students there should be a lot of students who are making the same mistakes. Therefore, I do not see much benefit in personalized feedback due to the impracticality of the context. 

I would consider it wiser to determine what are the common mistakes that the majority of the students made and provide the same feedback to all students on how to address these common mistakes. This will help the majority of the students without having to commit to the time-intensive effort of personalization.

If there is someone who wants additional explanation they can speak with the TAs.