Effects of undernutrition during late pregnancy on gluconeogenesis and ketogenesis in twin-pregnant ewes

Abstract

Summary. This study reports the interaction of protein and lipid mobilization on gluconeogenesis and ketogenesis after dietary restriction of ewe at the end of pregnancy. Two experiments were carried out using twin-pregnant Limousine ewes which were underfed either for the last 14 weeks or the last 4 to 6 weeks of pregnancy, depending on the lot (80 to 100 p. 100 of maintenance needs). Energy ingested at the end of pregnancy had much more marked effect on lamb weight at birth than body reserves midway through pregnancy. On the other hand, ketosis sensitivity was inversely proportional to dam weight gain during the first two-thirds of pregnancy. Amino acids were limiting factors of maternal gluconeogenesis when propionic acid level was low. This was expressed by a drop in some glucogenic amino acids, especially alanine, during undernutrition. On the other hand, glycine rose and variations in essential amino acids were limited. Protein mobilization was higher in the « high-low » lots than in the « low » lots, resulting in lower ketogenesis in the « high-low » lots for the same concentration of plasma free fatty acids. At the end of pregnancy, plasma acetate rose parallel to ketone bodies following endogenous production and less utilization by peripheric tissues.Introduction.

Feeding strategy during pregnancy for ewes with a large litter size. 2. Effect on blood parameters and energy status.

“…The observed plasma glucose levels at the end of pregnancy are in line with levels reported by Davies et al (1971), Ranaweera et al (1979Ranaweera et al ( , 1981 and Rémésy & Demigné (1979). Blood glucose levels as shown by Austin & Wilde (1985) and Stern et al (1979) are lower.…”

“…The observed levels of BHB in the plasma are comparable to levels reported by Rémésy & Demigné (1979) and Austin & Wilde (1985). However, we observed some very high levels in ewes suffering from acetonaemia.…”

“…In a limited number of blood samples with 2.8 to 3.6 mmol glucose per litre plasma we confirmed that blood glucose level was 20 to 25 % lower than the plasma glucose level. Low levels of glucose as observed in the plasma of ewes suffering from acetonaemia were also shown by Rémésy & Demigné (1979) in ewes suffering from acetonaemia and by Ranaweera et al (1979Ranaweera et al ( , 1981 in ewes suffering from acetonaemia induced by starvation. Low blood glucose levels in ewes suffering from acetonaemia were reported by Andrews (1982) and Wierda et al (1985).…”

Le métabolisme hépatique des glucides et des lipides chez les ruminants : principales interactions durant la gestation et la lactation

“…Les (Young, 1977) (Kronfeld, 1971 ;Baird, 1977 ;tabl. 2). Cette orientation métabolique est stimulée au niveau hépatique par le rapport glucagon/insuline élevé rencontré dans ces situations physiologiques (Basset, 1978 ;Brockman 1979 ;Gow et al, 19811 (Rémésy et Demigné, 1979 Baird, 1982 ;Kronfeld, 1982 Reid, 1980 ;Mazur et al, 1986c .…”

“…Bien que la glycine soit fortement captée par le foie, cet acide aminé à deux atomes de carbone est faiblement néoglu-cogénique. Par ailleurs, nous avons constaté (Rémésy et Demigné, 1979) (Demigné et al, 1986a) (Demigné etal., 1986a (Brockman et Mann, 1974 ;Gow et al, 1981 ;Grizard et al, 1986 Chilliard, 1985 Young, 1975 L'alimentation ne pouvant couvrir totalement les besoins de l'animal en fin de gestation ou en début de lactation, celui-ci mobilise ses réserves corporelles (tabl. 1).…”