Growth differences of male and female Göttingen minipigs during ad libitum feeding: a pilot study

Even though minipigs have been used in biomedical research for nearly half a century now, no specific nutrient requirements are available. For that reason a series of studies into the nutrient requirements of Göttingen minipigs were carried out. Firstly, a pilot study was carried out to determine the ad libitum feed intake (FI) during growth, as a reference for later feed restriction studies. Four male and four female minipigs were fed two types of diet, one standard pig diet (20.6% crude protein; 11.7% crude fat; 13.5 mJ/kg DM metabolizable energy) and one diet specially designed for minipigs (12.0% crude protein; 2.9% crude fat; 11.9 MJ/kg DM metabolizable energy). When fed ad libitum for 13 weeks, female Göttingen minipigs developed a significantly (P<0.05) higher body weight (BW) than males (27.4 vs 16.6 kg) on either diet. The large difference in growth between male and female Göttingen minipigs did not appear to be the result from differences in metabolizable energy intake. Metabolizable energy intake of male and female Göttingen minipigs could be predicted by ME=1877 kJxBW(0.61). Both male and female Göttingen minipigs became obese when fed ad libitum, defined by relative backfat thickness. Relative backfat thickness ranged from 5 to 13 cm/100 kg. Females had thicker relative backfat layers than males. Remarkably, no large changes in haematology and clinical chemistry occurred in ad libitum fed Göttingen minipigs as compared to reference values, and no abnormalities other than enlarged fat reserves were observed at necropsy. Apparently, Göttingen minipigs do not restrain FI voluntarily, and restricted feeding is therefore indicated to prevent obesity.