Goat adipose tissue mobilization and milk production level.
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Biomedical subjects
Publications and source records attributed to D Sauvant.
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In 5 French Alpine goats, omental adipose tissue acetyl-CoA carboxylase, glucose-6-phosphate deshydrogenase, malic enzyme and lipoprotein lipase activities significantly decreased during the third month of gestation, whereas plasma non-esterified fatty acid and triacyglycerol contents increased. This probably reflects an early decreasing rate of adipose tissue anabolism during gestation in the Goat. At the third week of lactation, anabolic activities relative to DNA content of adipose tissue were extremely low, and the tissue weight relative to DNA was lower than during gestation. Metabolic alterations of omental adipose tissue in early lactation do not seem to be related to milk production level. These results could contribute to a better control of the kinetic of body lipid stores during the reproductive cycle in high milk yielding ruminants.
5 French Alpine Goats were studied after normal or premature parturition. Mammary tissue acetyl-C oA carboxylase, glucose-6-phosphate dehydrogenase, malic enzyme and lipoprotein lipase (LPL) activities varied in parallel with milk fat secretion from the 3rd to the 9th week of lactation. Variations of mammary LPL activity and of long chain fatty acid secretion were positively highly correlated during that period. In goats with normal parturition, lipogenic activities seemed to reach a maximum level shortly after parturition. There was a positive correlation between mammary Ll activities and plasma non esterified fatty acid contents, possibly reflecting a relationship between adipose tissue mobilisation and mammary metabolism.
In the goat the passage from late pregnancy to early lactation is accompanied by a decrease of the epiploon lipoprotein lipase activity and an increase in the epiploon DNA content. The between-goat variations allow us to emphasize a linear relation between the lipoprotein lipase activity decrease and the reduction of the epiploon volume, expressed on a DNA basis. These parameters, used as indicators of the adipose tissue metabolic status, could contribue to the determination of a feeding strategy adapted to high yield milking Ruminants.
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Protein fractional synthesis rate (FSR) is a key-factor in the characterisation of ruminant metabolism. Published data from the literature were collected and statistically analysed to isolate the factors influencing FSR. FSR varied largely depending on the tissue considered, over a range from 1 to 20. FSR, with the plasma as the precursor pool for protein synthesis, was halved compared to that of the intracellular pool. The method for supplying the amino acid also significantly affects FSR since the flooding dose technique gave higher FSR estimates than the constant infusion technique. The choice of the labelled amino acid infused influenced FSR. There is a ranking order depending on the tissue or organ. The protein and energy levels of the diets significantly increased FSR, which raises the question of the body nitrogen requirements. Moreover, FSR values were dependent on the physiological status of the animals. To conclude, FSR values should be determined simultaneously with other biological parameters in order to obtain a realistic quantitative estimate of the nitrogen turnover rates during intermediary metabolism.
The present study was aimed at determining rumen phosphorus availability of some feedstuffs assessed with the nylon bag technique: forage (alfalfa), cereals (control-C wheat, formaldehyde treated-FT wheat, barley, corn), cereal by-products (wheat bran, wheat distillers, corn distillers) and meals (C and FT soya bean meals, rapeseed meals and sunflower meals). Rumen phosphorus availability was not uniform amongst the feedstuffs, varying from 33.1% (FT rapeseed meal) to 84.7% (C wheat). Alfalfa phosphorus release kinetics showed high bacterial phosphorus contamination. Technological treatments affected phosphorus content of by-products by either increasing (wheat bran and distillers) or decreasing (corn distillers) after germ extraction from the seed. Formaldehyde treatment decreasing rumen phosphorus availability (from 77.2% vs. 89.4% for wheat to 33.1% vs. 64.4% for the rapeseed meal) may depreciate the phosphorus nutritional value of FT meals.