I currently own two Heterozygous Piebald females (500 /600 g) that only eat frozen-thawed small rats. They're normally pretty good feeders, but lately the smallest has been a bit selective about eating. I decided yesterday to visit the local pet store for live rats. Although they looked absolutely huge, I purchased two medium feeder rats. These guys were only 118 and 121 grams, but they looked like giants. I wasn't sure if my smallest girl could handle one, but she surprised me. It's incredible how big of prey the can actually eat. She doesn't even seem to be bulging too much, either. (I'm hoping my larger girl will take the other rat tonight. She didn't seem too interested last night, but she did have a small meal Friday night.)
SIDE NOTE: Although I'm frightened each time I feed live, I figure if all the big breeders are trusting live with their $50,000 animals, I might as well trust live with my two hets. =?
Anyway...go for around 20-25% of your yearling snake's empty body weight. That's the advice that was given to me a few days ago, and it seems to be working.
Good Luck,
Chris
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"I don't know about you...but I find comfort in that." -- Cowboy