MIPS assembly program to read integer byte by byte
Firstly, you're missing some closing quotes on the data declarations at the top of the file. And you should specify that you make use of MARS specific calls.

However, when you read an integer using the "read integer" call, you read an 8-bit integer, that is, ranging from 0 to 255.

In your program you attempt to print four bytes out of this single byte, and therefore your program will print out garbage to the console.

You should simply remove the code that prints B2, B3 and B4.