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Peroxisome proliferator-activated receptor alpha pathway in dairy cows in a TMR vs. a pasture-based system.

M. Garcia-Roche



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Peroxisome proliferator-activated receptor alpha pathway in dairy cows in a TMR vs. a pasture-based system.
M. Garcia-Roche*1,2, G. Ca�ibe1, M. Ceriani1, A. Jasinsky1, A. Casal1, D. A. Mattiauda1, A. Cassina2, C. Quijano2, M. Carriquiry1. 1Departamento de Producci�n Animal y Pasturas, Facultad de Agronom�a, Universidad de la Rep�blica Uruguay, 2Centro de Investigaciones Biom�dicas-Departamento de Bioqu�mica, Facultad de Medicina, Universidad de la Rep�blica Montevideo, Uruguay.

To assess the effect of feeding strategy on the peroxisome proliferator activated receptor α (PPARA) pathway, multiparous Holstein cows (n = 24, 664 � 65 kg BW, 3.0 � 0.4 BCS, spring calving) were assigned in a randomized block design to a total mixed ration (TMR) fed ad libitum (70% forage: 30% concentrate) (G0) or grazing plus supplementation (G1) from 0 to 180 d postpartum (DPP). The G1 cows grazed Festuca arundinacea or Medicago sativa in 2 (18 h) or one session (10 h) depending on heat stress (30 or 20 kgDM/d) and were supplemented with 5.4 kgDM/d of a commercial concentrate or offered TMR (50% of G0 offer). From 180 to 250 DPP, all cows grazed Festuca arundinacea (10 h; 30 kgDM/d) and were offered TMR (50% of G0 offer). Liver biopsies were collected at 35, 110 and 250 DPP and mRNA abundance of PPARA and downstream genes: liver fatty acid binding protein (FABP), carnitine palmitoyltransferase 1A (CPT1), 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2) and acetyl-CoA carboxylase 1 (ACC1) were studied using real time PCR. Data were analyzed using a mixed model that included DPP, treatment and their interaction as fixed effects. Energy-corrected milk yield decreased (P < 0.01) by 12 kg/d at 250 DPP. Expression of PPARA mRNA decreased (P < 0.05) 30% at 110 DPP, but was not affected by feeding strategy. However, FABP mRNA was 1.5-fold greater for G0 than G1 cows. Alongside, HMGCS2 mRNA tended to be 1.6-fold greater for G1 than G0 cows, no differences due to DPP were observed. Hepatic FABP mRNA decreased at 250 DPP (0.78 and 0.71 vs. 0.47 � 0.19 for 35, 110 and 250 DPP, P = 0.07), while CPT1 mRNA was reduced at 110 DPP (0.77, 0.42 and 0.71 � 0.30 for 35, 110 and 250 DPP, P < 0.01). No differences were observed for ACC1 mRNA. Expression of PPARA mRNA correlated positively (r ≥ 0.4, P < 0.01), with CPT1, HMGCS2 and ACC1 mRNA consistent with its regulatory role in the expression of these genes. We conclude that increased PPARA, CPT1 and FABP expression may be attributed to increased lipid mobilization, alongside FABP overexpression in G0 could be linked to enhanced fatty acid transport while HMGCS2 overexpression in G1 could represent incomplete oxidation of fatty acids.


Biography: My work is based on elucidating the molecular mechanisms underlying metabolic adaptations during the lactation of dairy cows. I work specifically with energy metabolism, including mitochondrial function, post-translational modifications, gene expression and enzyme activity.