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Effects of LPS administration and subsequent nutrient restriction on systemic inflammation and hepatic steatosis in lactating dairy cows.

E. A. Horst

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06-23-2020

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Abstract:

T57
Effects of LPS administration and subsequent nutrient restriction on systemic inflammation and hepatic steatosis in lactating dairy cows.
E. A. Horst*, S. Rodriguez-Jimenez, E. J. Mayorga, M. A. Abeyta, B. M. Goetz, S. Carta, L. H. Baumgard. Iowa State University Ames, IA.

Objectives were to evaluate effects of repeated LPS exposure followed by nutrient restriction on inflammation and fatty liver in lactating cows. Cows (631 � 16 kg BW; 124 � 15 DIM) were enrolled in a study consisting of 3 experimental periods (P); during P1 (5d) cows were ad libitum-fed and baseline data were obtained. During P2 (7d), cows were assigned to 1 of 2 treatments: 1) saline-infused and pair-fed (PFFR; 5 mL saline on d1, 3, and 5; n = 6) or 2) LPS-infused and ad libitum-fed (LPSFR; 0.2, 0.8, and 1.6 �g LPS/kg BW on d1, 3, and 5, respectively; n = 6). During P3 (7d), all cows were feed restricted to 50% of P1 feed intake. On d3 of P3, LPSFR cows received an LPS bolus (0.8 �g LPS/kg BW) whereas PFFR cows received saline. Blood samples were collected on d1 and 3 of P1 and d1, 3, 5, and 7 of P2 and P3. Liver biopsies were obtained on d3 of P1, d7 of P2, and d3 and 7 of P3. Data were analyzed using PROC MIXED. Mild hyperthermia was observed for ~6h following each LPS bolus on d1, 3, and 5 of P2 and on d3 of P3 (0.6, 0.6, 0.8, and 0.5�C, respectively; P ≤ 0.04). Circulating LBP, SAA, and Hp increased in LPSFR relative to PFFR during P2 (3-, 4-, and 7-fold, respectively; P ≤ 0.04); LBP and SAA remained increased (2-fold) in LPSFR during P3 (P < 0.01). Circulating Hp from LPSFR steadily increased for the first 5d of P3 (5-fold relative to PFFR) and then returned to baseline (P < 0.01). Serum albumin and cholesterol from LPSFR decreased sharply from d1—3 of P2 and remained decreased for the duration of P2 relative to PFFR (12 and 16%, respectively; P ≤ 0.06). During P3, albumin and cholesterol decreased in LPSFR vs. PFFR cows (10 and 20%, respectively; P = 0.01). Liver fat content did not differ between treatments at the end of P2. Liver fat from LPSFR increased with time during P3, whereas it remained similar in PFFR cows (P = 0.04). Relative to P1, liver fat from both treatments increased during P3 (49 and 76% in LPSFR and PFFR cows, respectively; P < 0.01). In summary, repeated LPS administration followed by nutrient restriction induced a sustained systemic inflammatory response and increased liver fat content.

Keywords: inflammation, feed restriction.