1H NMR-based blood metabolomics in cold-stressed dairy goats

Abstract

The objective was to identify possible biomarkers of cold stress in blood of dairy goats. Eight lactating Murciano-Granadina dairy goats (2.13 ± 0.36 L/d; 70 ± 2 DIM; 41.75 ± 2.02 kg body weight) were maintained under 2 environmental conditions varying in ambient temperature: 1) 4 goats under thermoneutral (TN; 15 to 20°C), and 2) 4 goats under cold stress (CS; −4 to 8°C). In both environments, humidity averaged 60 ± 5% with 12–12h light-dark cycles. The experimental design was crossover with 2 treatments in 2 periods (21d each). Blood samples were collected weekly and analyzed by 1H nuclear magnetic resonance (H NMR) spectroscopy operating at 600 MHz. Multivariate analyses of data were carried out by the ChemoSpec package of R program and further analyzed by the web-based MetaboAnalyst program. Principal component and partial least square–discriminant analyses were used to identify possible metabolite markers. Goats under CS conditions had lower (P < 0.05) rectal temperature (−0.32°C), water consumption (−1.25 ± 0.24 L/d), and milk yield (−0.19 L/d) than TN goats. These results indicate that the low temperatures used in this experiment caused significant cold stress in goats. Metabolomics analysis revealed that CS goats had higher α- and β-glucose in plasma. This is in agreement with greater (P < 0.05) blood glucose in CS (66.7 mg/dL) than TN goats (64.1 mg/dL). There was also an increment in blood phosphatidylcholine, which could be related to lipid metabolism as CS goats mobilized body fat reserves and had greater (P < 0.05) blood nonesterified fatty acids concentrations (0.215 mmol/L) than TN goats (0.107 mmol/L). Tyrosine levels were greater in CS goats, which could be used for the synthesis of catecholamines. In conclusion, the H-NMR was a useful technique to define differences in blood metabolome by cold stress. The metabolic changes detected were mainly related to the increment in glucose, lipid metabolism, and neurotransmitters synthesis. Study funded by Project AGL2013–44061-R (Plan Nacional, MINECO, Spain)