RESUMEN
Reduced liver function, increased oxidative stress, and inflammation in early lactation negatively impact lactation performance and health of fresh cows. Previous findings from our group demonstrated that branched-chain amino acids (BCAA) infusion improved lactation performance and branched-chain ketoacids (BCKA) infusion decreased liver triglyceride (TG) in fresh cows. The objectives of this study were to determine the effect of BCAA and BCKA on blood and liver biomarkers of liver function, oxidative stress, and inflammation as well as expression of genes regulating inflammation and antioxidant metabolism in the liver. Thirty multiparous Holstein cows were used in a randomized block design receiving continuous abomasal infusion for 21 d after parturition. Treatments (10 cows each) were control (CON), cows abomasally infused with 0.9% saline; BCA, cows abomasally infused with BCAA (67 g valine, 50 g leucine, and 34 g isoleucine); and BCK, cows abomasally infused with BCKA (77 g ketovaline, 57 g ketoleucine, and 39 g ketoisoleucine). All cows were randomly assigned to treatments after parturition and received the same diet throughout the experimental period. Blood was collected at 3, 7, 14, and 21 d postpartum for liver function, oxidative stress, and inflammation biomarker profiling. Liver was also harvested on 7, 14, and 21 d postpartum for quantification of glutathione, protein carbonylation, and expression of genes. ANOVA was conducted for all data using PROC GLIMMIX in SAS. No treatment differences were observed for liver function biomarkers (bilirubin, gamma-glutamyl transferase, and aspartate aminotransferase). Cows receiving BCAA had lower blood NO2- and NO3- concentrations compared with CON. A tendency for lower advanced oxidized protein products was also observed in BCA cows compared with CON. Additionally, on d 7, BCA cows had lower protein carbonylation in the liver compared with CON. In contrast, BCK cows had higher plasma thiol and albumin, as well as liver reduced and total glutathione compared with CON cows. Compared with CON, BCK cows had higher expression glutathione reductase in the liver. Overall, these results suggest favorable alterations in oxidative stress and inflammation status in fresh cows receiving BCAA or BCKA infusion during the first 3 weeks of lactation, which likely contributed to previously-observed changes in lactation performance and liver TG concentrations. Future work is required to evaluate the interrelated metabolism of BCAA and BCKA to better understand their effects on oxidative and immune metabolism.
RESUMEN
We examined the effects of a supplement of plant polyphenols extracts of green tea, capsicum, and fenugreek, and electrolytes ([Na+, K+]; AXT, Axion ThermoPlus, CCPA, France] during summer heat load on production, welfare, and oxidative stress proteins in adipose tissue (AT) of dairy cows. A total of 42 multiparous mid-lactation cows were divided into 3 groups during summer, and were fed for 2 wk either a standard milking cow diet (CTL, n = 14) or diets supplemented with 100 g/d of AXT (100AXT, n = 14), or 150 g/d of AXT (150AXT, n = 14), while being cooled 5 times a day. Then, half of the cows from each dietary treatment were cooled (CL) or not cooled (NCL) for 2 wk, after which the cooled and uncooled groups were switched for additional 2 wk. Cows were milked 3 times a day, and milk composition was analyzed at the end of each 2-wk period. Vaginal temperature (VT) was measured for 3 consecutive days in each period. Biopsies of subcutaneous AT were taken from 10 NCL cows (5 each of CTL and 150AXT) at the end of the period and examined by liquid chromatography-tandem mass spectrometry proteomics analysis. Data were analyzed with PROC MIXED of SAS (version 9.2, SAS Institute Inc.). The model included the effects of dietary treatment, cooling regimen, period, and their interactions. Protein and mRNA abundances and proteomic data (P ≤ 0.05 and fold change [FC] ± 1.5) were analyzed by t-test. Milk yields and 4% fat-corrected milk (FCM) were higher in 100AXT than in CTL; milk components were not different. Dry matter intake (DMI) was higher in 100AXT than in CTL. The effect of cooling and the interactions of period × cooling were significant for DMI, 4% FCM, energy-corrected milk, and milk/DMI. The proportion of time that VT was >39°C was lower in 100AXT and in 150AXT than in CTL. Daily rumination time was greater in 150AXT than in CTL, and lying time was greater in 100AXT and 150AXT than in CTL. Proteomics of AT demonstrated that 150AXT had increased abundances of peroxidasin (FC = 1.6), microsomal glutathione S-transferase 2 (FC = 2.5), and heme oxygenase 1 (FC = 3.6) compared with CTL. Top enriched canonical pathways included acute phase response signaling, Nrf2-mediated oxidative stress response, and lipopolysaccharide (LPS)/IL-1-mediated inhibition of RXR function. Immunoblots of AT showed a higher abundance of the transient receptor potential vanilloid 1 and of LPS binding protein in AT of 150AXT compared with CTL. Supplementation of AXT increased DMI, milk, and 4% FCM, lowered VT, improved welfare indices, and enriched the AT with Nrf2-oxidative stress response and acute phase response proteins in heat-stressed dairy cows.