I mentioned the date these studies were conducted in my second post, so it is understandable to look at this study quite objectively.
Personally I think stress is a major contributor, stress and adrenaline has such a profound effect on crocs that many physiological parameters are influenced by it. My professor was C.E. Franklin who has demonstrated the adrenergic effect on crocodilian lingual salt glands and cardiac function. Whilst I have no primary literature to support such hypothesis I would initially suspect stress would play a primary role in the difference. I will try and obtain a copy of the paper to see what is mentioned in the discussion in regards to this matter.
Ok so after reading a few articles I have taken out snippets of relevant findings, but essentially the difference is not known and I can't find any remotely relevant recent publishing on the matter. Some of the possible suggestions are stress, frequent filling of the stomach, fat diet in captivity, metabolic scaling and possible clutch variation.
Direct quote (without intext references) from the discussion in Webb (1991):
"The reason food conversion rates in the wild are much higher than those reported in captivity are unknown. Conditions in captivity could be far more stressful than is generally recognized, although corticosterone levels in captive A. mississippiensis, maintained at low densities, suggest this is not the case. In the wild, C. porosus do not appear to have the opportunity to fill their stomachs each time they feed, which usually occurs in captivity. This raises the possibility that the physiological mechanisms associated with the digestion and assimilation of food may not function as efficiently when the stomach is repeatedly filled to capacity. Captive hatchling C. porosus fed daily have food conversion rates (28%) that were appreciably lower than those fed every two days (40%)."
He also mentioned the above average abundance of rats in the study site during the study which were recorded in the stomach contents of some animals.
The wild study sample attains an average 730 mm TL and 870g in one year, whereas the average farm raised individual attained 750 mm TL and 1360g in one year. So captive stock are much heavier per unit length.
From Garnett and Murray (1986):
Investigating the parameters affecting the growth of estuarine crocodile. Individuals from some clutches responded positively to stress, while those from other clutches responded negatively. It was concluded that clutch variations explained the majority of the variation in all variables in this study, it was undetermined whether the clutch-related factors were genetic or environmental.
From Garnett (1988):
Up to 92% of protein in captive estuarine crocodiles was digested but protein was adversely affected by high levels of dietary fat.
and being slammed makes ya stronger... christ knows i have been flamed to many times :S alot of people will go mice as they see it as a varied diet, offering the whole animal and providing nutrition from hair etc.
