Increased dietary methionine, lysine and histidine supply modulated the heat stress-induced metabolic remodeling of dairy cows

Increasing dietary Met, Lys, and His supply without increasing the dietary protein content was reported to partially alleviate the productive and physiological impact of heat stress. Nevertheless, the metabolic pathways involved are yet to be identified. Thus, we aimed to explore the metabolic pathways associated with these positive effects and develop new metabolomics-based hypotheses. Twelve lactating Holstein cows (primiparous, n = 6; multiparous, n = 6; 42.2 ± 10.6 kg/d milk yield; 83 ± 28 days in milk) were enrolled in two 3×3 replicated Latin squares consisting of 14-day treatment periods: heat stress [HS; max. Temperature Humidity Index (THI) 84, 16.8% crude protein (CP), 1,741 g/d metabolizable protein (MP), 108 Lys, 33 Met, and 37 His (g/d)], pair feeding in thermo-neutrality (TN; max. THI 64, same diet as HS), and HS with increased Lys, Met and His supply [HS+AA; max. THI 84; 17.0% CP, 1,730 g/d MP, 179 Lys, 58 Met, and 45 His (g/d)]. Blood plasma and milk were sampled on day 14 for metabolomics profiling. Several amino acids (AA) and derivatives differed between the treatments. Plasma and milk Met, Val, Trp and α-amino adipic acid concentrations were highest in HS+AA (false discovery rate-P (FDR) < 0.05). Moreover, only plasma Lys and milk His were highest in HS+AA (FDR < 0.05). Some phosphatidylcholines (PC) and diglycerides had lower concentrations in HS than TN (FDR < 0.05), while HS+AA had similar concentrations as TN. The pathway enrichment analysis revealed that the AA-related pathways were more significantly affected in multiparous than in primiparous cows. Our results suggest that increased supply of Met stimulated PC synthesis in HS+AA to similar concentrations as in TN. Increased Lys supply likely elevated the oxidation rate of Lys and downregulated the catabolism of other essential AA (EAA) such as Val and Trp, stimulating milk protein synthesis. No clear associations were found related to His availability. In conclusion, partial amelioration of productive and physiological effects of heat stress associated with increased dietary Met and Lys supply were likely explained by stimulated PC synthesis and increased plasma and milk concentrations of other EEA

Plasma concentrations of branched-chain amino acids differ with Holstein genetic strain in pasture-based dairy systems

International audienceAbstract In pasture-based systems, there are nutritional and climatic challenges exacerbated across lactation; thus, dairy cows require an enhanced adaptive capacity compared with cows in confined systems. We aimed to evaluate the effect of lactation stage (21 vs. 180 days in milk, DIM ) and Holstein genetic strain (North American Holstein, NAH , n = 8; New Zealand Holstein, NZH , n = 8) on metabolic adaptations of grazing dairy cows through plasma metabolomic profiling and its association with classical metabolites. Although 67 metabolites were affected ( FDR < 0.05) by DIM, no metabolite was observed to differ between genetic strains while only alanine was affected ( FDR = 0.02) by the interaction between genetic strain and DIM. However, complementary tools for time-series analysis (ASCA analysis, MEBA ranking) indicated that alanine and the branched-chain amino acids ( BCAA ) differed between genetic strains in a lactation-stage dependent manner. Indeed, NZH cows had lower ( P -Tukey < 0.05) plasma concentrations of leucine, isoleucine and valine than NAH cows at 21 DIM, probably signaling for greater insulin sensitivity. Metabolic pathway analysis also revealed that, independently of genetic strains, AA metabolism might be structurally involved in homeorhetic changes as 40% (19/46) of metabolic pathways differentially expressed ( FDR < 0.05) between 21 and 180 DIM belonged to AA metabolism

Metabolic, productive and reproductive responses to postpartum short-term supplementation in primiparous beef cows

The objective of this study was to evaluate the effect of a short-term supplementation with rice bran (2 kg/cows/day) on the endocrine and metabolic profiles and hepatic gene expression, associated with the reproductive response in beef cows in grazing conditions. Thirty-eight primiparous beef cows (Hereford, Angus and Hereford × Angus) were used in a randomized block design according to genotype, calving date and body condition score at calving (BCS). At 64±14 days postpartum (day 0 of the experiment), cows were assigned to two nutritional treatments: i) control, grazing native pastures (CON, n=19) and ii) supplemented (SUP, n = 19) for 21 days (days 1 to 21 of the experiment). Blood samples were collected at 0, 7 and 22 days and liver biopsies were obtained at day 22 to determine the abundance of mRNA of growth hormone receptor (GHR), insulin-like growth factor -I (IGF1), and its binding proteins -2 and -3 (IGFBP2 and IGFBP3), and insulin receptor (INSR) using SYBR-Green real-time RT-PCR with hypoxanthine phosphoribosyltransferase as endogenous control. Short-term supplementation with rice bran did not modify either cow BCS or BW, or calf BW or average daily gain. However, it decreased by 11 days the length of postpartum anestrus of primiparous cows in grazing conditions, associated with increased concentrations of glucose and insulin, and reduced hepatic expression of IGFBP2 mRNA at the end of the experimental period

Hepatic metabolism of grazing cows of two Holstein strains under two feeding strategies with different levels of pasture inclusion.

The objective of the study was to characterize adaptations of hepatic metabolism of dairy cows of two Holstein strains with varying proportions of grazing in the feeding strategy. Multiparous autumn calving Holstein cows of New Zealand (NZH) and North American (NAH) strains were assigned to a randomized complete block design with a 2 x 2 factorial arrangement with two feeding strategies that varied in the proportions of pasture and supplementation: maximum pasture and supplementation with a pelleted concentrate (MaxP) or fixed pasture and supplementation with a total mixed ration (FixP) from May through November of 2018. Hepatic biopsies were taken at - 45 ± 17, 21 ± 7, 100 ± 23 and 180 ± 23 days in milk (DIM), representing prepartum, early lactation, early mid-lactation and late mid-lactation. The effects of DIM, feeding strategy (FS), strain and their interactions were analyzed with mixed models using repeated measures. Cows of both strains had similar triglyceride levels, mitochondrial function and carnitine palmitoyltransferase activity in liver during lactation. However, there was an effect of DIM and FS as liver triglyceride was higher for the MaxP strategy at 21 DIM and both mitochondrial function and carnitine palmitoyltransferase activity in liver were lower for the MaxP strategy at 21 DIM. Hepatic mitochondrial function and acetylation levels were affected by the interaction between strain and feeding strategy as both variables were higher for NAH cows in the MaxP strategy. Mid-lactation hepatic gene expression of enzymes related to fatty acid metabolism and nuclear receptors was higher for NZH than NAH cows. This work confirms the association between liver triglyceride, decreased hepatic mitochondrial function and greater mitochondrial acetylation levels in cows with a higher inclusion of pasture and suggests differential adaptative mechanisms between NAH and NZH cows to strategies with varying proportions of grazing in the feeding strategy

Avances en el conocimiento de la vaca lechera durante el período de transición en Uruguay : Un enfoque multidisciplinario

La transición del estado preñada no lactante al no preñado lactante es un período de cambios drásticos para la vaca, la cual debe adaptar su metabolismo a las fuertes exigencias que le demanda la producción. Del equilibrio con que la vaca resuelva este proceso dependerá la capacidad de maximizar la producción y la calidad de la leche, de evitar enfermedades metabólicas y asegurar la siguiente preñez. La mejora nutricional, la selección genética y el manejo animal han aumentado la producción de leche en las últimas décadas, y esto se asocia a una disminución del desempeño reproductivo y al aumento de problemas sanitarios. Esta revisión resume trabajos realizados en los últimos años en Uruguay, enfatizando en el manejo diferencial de nutrientes, la respuesta en comportamiento ingestivo, los mecanismos endocrino-moleculares de la partición de nutrientes y su relación con la fertilidad en vacas lecheras. Se reportan experimentos que estudian la eficiencia productiva de diferentes biotipos lecheros y razas. Se describen trabajos en salud que identifican el período de transición como período de riesgo a enfermedades metabólicas, infecto-contagiosas y traumáticas. Se concluye que los estudios integrados en problemas de relevancia nacional es la respuesta necesaria a sistemas biológicos complejos como lo es la vaca lechera durante el período de transición en pastoreo