Thanks a ton guys. Feeling better after reading all your replies. He doesn't beg for food at all. In fact, we're the ones doing the begging, begging him to eat. The person we bought Zulu from (when he was 2.5 months old) was feeding him Science diet puppy lamb and rice. I gradually switched him to Canidae als. Since Zulu didn't bother to eat, we switched him to Solid Gold puppy formula, then Wellness puppy, Timberwolf lamb, barley & apples and currently on Nutro Holistic puppy. We've tried the 20 min rule, leaving the food for 20 min and removing the leftover. Well, it doesn't help. So finally we've decided to stick to Nutro for a while, as there's been a lot of diet changes already. Am keeping my fingers crossed.
Once again, thanks everyone.
K