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A static balance model to quantify and explore mammary nutrient metabolism in lactating sows

Abstract : Quantitative estimates of mammary nutrient uptake and metabolism in sows are scarce, despite being central for the feeding of lactating sows. The aim was to quantify uptake, metabolism and output of nutrients by the mammary gland and to identify factors regulating mammary metabolism in lactating sows. Results from four studies were integrated into a dataset including data on litter performance, milk composition, and mammary arterial-venous differences (AV–difference) of amino acids (AA) and main energy metabolites. Milk yield (based on litter gain and size) and composition were used to estimate milk nutrient output. Mammary plasma flow (based on Phe+Tyr as flow marker) and AV–differences were used to estimate net mammary fluxes. The dataset constituted the basis for the construction of a static model, in which glucogenic carbon (C), ketogenic C, and AA C were prioritised for synthesis of lactose, fat, and protein, respectively. Surplus C was used for energy processes supporting milk synthesis (for the de novo synthesis of fat, lactose, peptide bond formation, milk protein and mammary tissue turnover, and transmembrane transport of glucose and amino acids) and consequently directed to a CO2 pool. The remaining glucogenic C was used in the carbon skeleton of de novo fat. The model suggested that glucogenic C constituted 34% of milk fat C and 88% of net mammary CO2 release. In addition, 45% of the mammary CO2 release was used to support de novo fat synthesis. Accordingly, 46% of glucogenic C was directly (31%) or indirectly (15%) associated with milk fat synthesis. More than 90% of mammary AA C was secreted in milk protein. Simultaneously, nitrogen balances of individual AA and relationships between AA availability and uptake suggested that the availability of branched-chain AA, Arg, and Phe influence mammary uptake of at least for these AA. In conclusion, milk protein synthesis appears to be the main driver of total mammary AA uptake, but of less importance for some individual AA. Moreover, de novo fat synthesis appears to be of great importance for mammary energy efficiency.
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https://hal.inrae.fr/hal-03047225
Contributor : Jacob van Milgen <>
Submitted on : Tuesday, December 8, 2020 - 5:42:41 PM
Last modification on : Friday, March 19, 2021 - 12:08:02 PM

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  • HAL Id : hal-03047225, version 1

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U Krogh, Hélène Quesnel, Nathalie Le Floc'H, A Simongiovanni, Jaap van Milgen. A static balance model to quantify and explore mammary nutrient metabolism in lactating sows. 71. Annual Meeting of the European Federation of Animal Science (EAAP), EAAP, Dec 2020, Virtual meeting, Portugal. ⟨hal-03047225⟩

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