Effects of fasting on blood composition and nitrogen losses in the adult sheep depending on previous diet and body weight

Abstract

Summary. In order to study the profiles of blood composition and nitrogen losses during fasting, groups of adult sheep that had previously received diets with variable intake levels were fasted during 8-day periods. A decrease in blood ketone concentration was observed during the first day, followed by a strong increase after 36 to 48 hrs. After The role of the ketone bodies and the protein reserves in meeting energy needs and in maintaining glycemia during fasting have been discussed.

Effects of long-term ad libitum feeding on plasma lipid components and blood glucose, β-hydroxybutyrate and insulin concentrations in lean adult sheep

“…This pattern in the ad libitum fed sheep shows that increasing FFA concentration was associated with stable and high body fat content and a decline in food intake. In previous papers (Bouchat et a/., 1980 ;1981) we confirmed the findings of other authors (GOnzel and Giesecke, 1974 ;Thompson et al, 1975 ;Thye et al, 1970), demonstrating that fasting induces a rapid increase in the FFA concentration from the first day of fasting and that the concentration tends to stabilize after 5-6 days of fasting. Moreover, this concentration is influenced by the nature and the level of food offered (Bouchat et al, 1981).…”

“…The fatty acid composition of the lipid fractions was comparable with that obtained previously (Bouchat et al, 1980(Bouchat et al, , 1981 and analogous results were reported by Garton (1960) and Lindsay and Leat (1977).…”

“…We also observed previously that this lipid distribution was only slightly influenced by the nature of the food and the intake level (Bouchat et al, 19811, by fasting (Bouchat et al, 1980) and by the time of day (Doizé et al, 1979). Feeding and physiological conditions seemed to have no effect on blood lipid distribution.…”

“…In The fatty acids of blood lipids, which change in the present study, were the same as those influenced by fasting (Bouchat et a/., 1980(Bouchat et a/., , 1981 and by the nature of the diet and the level of food given (Bouchat et al, 19811. Changes in the food intake as a result of the fattening state had no effect on blood glucose concentration in the experimental sheep. The values remained very close to those of the control group throughout the test.…”

“…In ruminants p-hydroxybutyrate, deriving from the hepatic metabolism of acetyl CoA and principally from volatile fatty acid transformation in the rumen wall, has an important metabolic function ; during fasting (Bouchat et al, 1980(Bouchat et al, , 1981 and after feeding (Doizé et al, 1979) (De Jong, 1979 ;Kamalu and Trenkle, 1978 ;Nicholson, 1979). An increase of insulinemia occurs directly after feeding and low values are obtained during fasting (Bouchat et al, 1981).…”