Untersuchungen über ernährungsphysiologische Wirkungen von Futterfetten in Rationen für wachsende Schweine

: Three groups of male, castrated piglets of the German Landrace breed, weight range 3-30 kg, were used to study the relation between fattening performance and blood parameters when feeding rations containing different amounts of fat. The fat content of the rations was either 5% (group I), 18% (group II) or 35% (group III). Concomitantly with the increased metabolizable energy (ME) content of the ration the content of digestible protein (DP) was increased and the amount of feed reduced in order to guarantee an equal intake of ME and DP in all three groups. The digestibility of the crude nutrients and protein retention of the subjects were determined in nine subsequent trials each lasting 7 days. At a body weight of 27 kg the blood concentrations of insulin, glucose, free fatty acids, neutral lipids and cholesterol were determined at different times after feeding. In addition, an oral glucose tolerance test was made and the in-vitro synthesis of fat from glucose was measured. The apparent digestibility of fat amounted, unexpectedly, to approximately 94% on the high rat rations II and III. In all groups a significant positive relation between body weight and digestibility of the fat was determined. Despite equal daily intakes of ME in all groups, in group III daily weight gain and protein retention were 7% (p less than 0.01) and 4% (p less than 0.01) higher than in group I, respectively. Blood urea levels of group III were 67% (p less than 0.01) lower than in group I. The mean daily nitrogen retention of the three groups rose gradually from 4 g at a body weight of 5 kg to 16-17 g at a body weight of 25 kg. The feed conversion of group I was lower by 22 and 36% as compared to groups II and III, respectively. Highly significant differences were observed among either groups (p less than 0.01). It has been calculated that in group III the consumption of ME/kg weight gain was about 8% (p less than 0.05) lower than in the two other groups. According to the increased fat percentage of the rations, body protein content diminished from 17,1% in group I to 16,5 and 16% in groups II and III, respectively. Only the difference between groups I and III proved to be significant (p less than 0.05). In group I feed intake resulted in an increase in the insulin level by 55% (p less than 0.05) whereas glucose did not change significantly.(ABSTRACT TRUNCATED AT 400 WORDS)