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The effects of colostral fat level on fat deposition and plasma concentrations of glucose, insulin, and free fatty acids (FFA) were determined in 28 newborn pigs during the fist postnatal day. Soon after birth, pigs were allotted to four treatments groups. Group 1 was killed at birth. The remaining pigs were fed intragastrically sow colostrum that contained high (10.2%; HFC), normal (4.8%; NFC) or low (1.0%; LFC) levels of total fat at the rate of 15 to 18 &g birth weight at 65to 70-min intervals. A total of 21 feedings was provided and pigs were killed 1 h after the last feeding. Body fat deposition increased linearly (P < .01) with the amount of ingested fat by .32 (k .04) g per l-g increase in fat intake. Fatty acid composition of the pigs changed toward that of the colostrum with increased fat in colostrum. More liver glycogen was lost (P < .01) in pigs given LFC. Plasma concentrations of glucose and insulin were similar in pigs fed HFC and NFC. After the 11th feeding (14 h postnatal), LFC resulted in lower plasma glucose concentrations (P < .05) than HFC or NFC. Plasma insulin concentrations also were lower in pigs fed LFC. Plasma FFA concentrations remained unchanged in pigs fed LFC but increased with both fat content in colostrum (P < .05) and time (P < .OS) in the other two groups. Colostral fat plays a major role in the supply of energy and in glucose homeostasis in the neonatal pig.

The direct effect of hypothermia on the inhibition of insulin secretion may result from inhibition of the availability of energetic substrates and/or the lack of metabolic signals. In order to verify this hypothesis, the insulin secretion and the main metabolic glucose pathways were measured during the incubation of rat islets. In the presence of 16.7 mmol glucose/l and at 37 degrees C, insulin secretion was 925 +/- 119 microU/2 h per ten islets. With the same experimental conditions, glucose utilization, determined as the formation of 3H2O from [5-3H]glucose was 2225 +/- 184 pmol/2 h per ten islets, glucose oxidation measured as the formation of 14CO2 from [U-14C]glucose was 673 +/- 51 pmol/2 h per ten islets, pentose cycle determined as the formation of 14CO2 from either [1-14C]glucose or [6-14C]glucose was 37 +/- 5 pmol/2 h per ten islets; glucose oxidation by the tricarboxilic acid cycle, calculated to be the difference between glucose oxidation and pentose cycle values, was 636 pmol/2 h per ten islets. Hypothermia highly inhibited glucose-induced insulin secretion and glucose utilization. Inhibition of insulin secretion was partial at 27 degrees C since it was 2.5 times lower than that at 37 degrees C, and it was complete at 17 degrees C. Glucose oxidation in the tricarboxilic acid cycle was markedly inhibited by hypothermia since the inhibition coefficient (Q10) between 37 and 27 degrees C was 5. In contrast, glucose oxidation in the pentose phosphate shunt was enhanced at 27 degrees C, reaching 92 +/- 17 pmol/2 h per ten islets, and it was inhibited relatively little at 17 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

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Le canard de Barbarie présente une meilleure aptitude à la stéatose hépatique que le canard Pékin qui présente un engraissement périphérique au niveau des tissus adipeux et musculaires plus important. En effet, la lipogénèse hépatique est plus efficace chez le canard de Barbarie. Par contre, sa capacité à exporter les lipides hépatiques est inférieure. Par ailleurs, l’activité de la lipoprotéine lipase est également plus faible chez le canard de Barbarie, en particulier en fin de gavage, ce qui favorise le retour des triglycérides sanguins vers le foie. Les canards hybrides, hinnies et mulards présentent toujours des valeurs intermédiaires à celles des espèces parentales pour l’ensemble de ces paramètres à l’exception de la capacité d’ingestion et du poids du foie gras pour lesquels ils bénéficient d’un effet d’hétérosis.

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