What are the sizes of BG and LMB right now and what does the population of each look like? Feeding the BG good food should help their growth, do your LMB eat feed, too? The common method of increasing BG size is to have lots of small, hungry LMB that eat the young BG and allow a smaller number of BG to grow to larger sizes. However, if yours are being fed competition for food shouldn't be an issue, I don't think. Removing any small, runty LMB will help the remaining ones grow as it'll lessen the competition and allow the remaining ones access to a higher percentage of available forage.
