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Responses to methionine, lysine plus histidine and energy supply on mammary metabolism in dairy cows

Abstract : Our objective was to study how balancing Lys, Met and His (LMH) at 2 supplies of net energy of lactation (NEL) affect milk yield and composition. Four Holstein cows received duodenal infusion of 2 amino acids (AA) mixtures and 2 dietary levels of NEL (E-: 31.5 vs E+: 35.9 Mcal/d), combined in factorial arrangement, distributed in a 4×4 Latin square, with 3-wk periods. The 2 AA mixtures, both providing 92±2 g/d of PDI (metabolisable protein in INRA, 2018), contained (g/d) Lys (28), Met (9), His (9) and non-essential AA (NEAA) in LMH+ or only NEAA in LMH-. Diets plus infusions provided 5.8, 2.0 and 2.0% of PDI of Lys, Met and His respectively in LMH- compared to 7.1, 2.4 and 2.4% PDI in LMH+; LMH+ met INRA (2018) requirements of 7.0, 2.4 and 2.4% PDI for these 3 AA, respectively. The mammary uptake (MU) of metabolites were measured on day 20 (6 samples at 2-h intervals) of each period, mammary plasma flow being estimated using the Fick principle (Phe+Tyr). Analyses of variance of these data included the effects of LMH, NEL and interaction using a MIXED procedure (SAS) with cow as random effect. No interaction was observed on milk composition (P>0.22). Balancing LMH tended to increase (P=0.07) and increasing NEL supply increased (P≤0.02) milk and fat yields averaging respectively 28.2, 29.6, 30.1 and 31.2±1.33 kg/d and 1,289, 1,317, 1,363 and 1,410±55.1 g/d for E-LMH-, E-LMH+, E+LMH- and E+LMH+. Both treatments increased (P<0.05) milk protein yield (828, 916, 927 and 962±39.2 g/d for E-LMH-, E-LMH+, E+LMH- and E+LMH+). The increased milk protein yield were linked to increased MU of LMH in response to LMH supply (+ 8.4 mmol N/h; P=0.01) and to increased MU of essential AA other than LMH in response to NEL supply (+ 11.8 mmol N/h; P=0.05). Increasing NEL supplies increased milk fatty acids de novo synthesised within the mammary gland (+58 mmol C/h; P=0.02) and MU of β-hydroxybutyrate (+171 mmol C/h; P=0.03). It increased milk yield through an increased lactose yield (+ 97 g/d; P=0.01) while LMH supply had no effect on it (P=0.21). Glucose and acetate MU only tended to be higher in E+LMH+ than in the other treatments (LMH × E: P≤0.06). In conclusion, balancing LMH increased milk, protein and fat yields through different mechanisms than increasing NEL supply indicating the high mammary gland metabolic flexibility to nutrient availability.
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https://hal.inrae.fr/hal-03142894
Contributor : Emilie Bernard <>
Submitted on : Tuesday, February 16, 2021 - 1:30:09 PM
Last modification on : Thursday, March 18, 2021 - 1:04:03 PM

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Cléo Omphalius, Helène Lapierre, Laurence Bernard, L Bahloul, Sophie Lemosquet. Responses to methionine, lysine plus histidine and energy supply on mammary metabolism in dairy cows. 71. Annual Meeting of the European Federation of Animal Science (EAAP), EAAP, Dec 2020, Virtual meeting, Portugal. ⟨hal-03142894⟩

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