Exposure to lipopolysaccharide in utero alters the postnatal metabolic response in heifers

This study was designed to determine the effect of prenatal lipopolysaccharide (LPS) exposure on the postnatal metabolic response to an LPS challenge in beef heifers. Pregnant, crossbred cows (n = 50) were assigned to a prenatal immune stimulation (PIS; n = 25; administered 0.1 µg/kg BW LPS subcutaneously 233 ± 15d of gestation) or saline treatment group (Control; n = 25). Birth and weaning BW of calves were collected. There was not (P\u3e 0.05) a treatment × gender interaction for birth weight or 205-d adjusted weaning BW. Treatment did not affect (P\u3e 0.05) birth BW, but steers and heifers of PIS cows had greater (P \u3c 0.02) 205-d adjusted weaning BW than offspring from Control cows. From the 2 prenatal treatment groups, heifer calves (n = 12 PIS, 11 Control) were identified at weaning (238 ± 15 d of age) to subsequently receive an LPS challenge. On d 0, heifers were fitted with indwelling jugular catheters and were moved into individual pens. On d 1, heifers (fed at 0600 h) were challenged i.v. with LPS (0.5 µg/kg BW) at 0 h (1000 h). Blood samples were collected at 30-min intervals from -2 to 8 h and again at 24 h relative to the LPS challenge. There was a treatment × time interaction (P \u3c 0.01) for cortisol; PIS heifers had greater cortisol from 4 to 6.5 h post-LPS challenge (P \u3c 0.001). There was a treatment × time interaction (P = 0.04) for serum glucose such that glucose was greater (P = 0.01) in PIS than Control heifers at 0.5 h, but was greater in Control than PIS heifers at 2, 4.5, and 7 h post-LPS challenge. This resulted in overall time (P \u3c 0.01) and treatment (P \u3c 0.01) effects such that Control heifers had greater glucose concentrations than PIS heifers. There was a tendency (P = 0.10) for a treatment × time interaction for serum NEFA, such that NEFA was greater in Control than PIS heifers at -2, -1.5, and 7 h relative to the LPS challenge (P ≤ 0.02). Also, there were time (P \u3c 0.01) and treatment effects (P \u3c 0.01) for NEFA with Control heifers having greater NEFA than PIS heifers. Serum BUN was affected by a treatment × time interaction (P \u3c 0.01). Concentrations of BUN were greater in PIS heifers from -1.5 to -1 h, 1 to 2 h, at 4 h, and from 5 to 24 h relative to the LPS challenge. These results demonstrate postnatal growth and the metabolic responses of weaned beef calves can be significantly altered with a single exposure to LPS in utero

Dehydrated citrus pulp alters feedlot performance of crossbred heifers during the receiving period and modulates serum metabolite concentrations before and after an endotoxin challenge

English × Continental heifers (n = 180) were sourced in 2 loads (219.3 ± 16.0 and 221.4 ± 16.4 kg, respectively) from commercial auction barns to study the effects of feeding dehydrated citrus pulp (DCP) on feedlot performance of newly received heifers. A completely randomized block design was used with BW nested within arrival load and blocked by BW into 3 dietary treatments (36 pens, 5 heifers/ pen, 12 blocks, 3 pens/block, and 12 pens/treatment). Treatment diets contained 1) 0% DCP (control diet [CON]), 2) 10% DCP, or 3) 20% DCP on a DM basis. Diets containing DCP were exchanged with steamflaked corn on a 1:1 basis. Cattle were fed a 63, 73, and 83% concentrate diet from d 0 to 28, d 28 to 42, and d 42 to 56, respectively. Over the 56-d trial period, as the amount of dietary DCP increased, DMI decreased (P = 0.01), ADG decreased (P \u3c 0.01), and G:F decreased (P = 0.02). From d 0 to 28, there was no difference in the observed minus the predicted NEg of the diet (P = 0.73); from d 28 to 42, there was a linear increase in NEg favoring DCP treatments (P \u3c 0.01); and from d 42 to 56, there was a linear decrease in NEg against the DCP treatments (P \u3c 0.01). At the conclusion of the trial, a subset of heifers (n = 22; 307.89 ± 3.32 kg on d 63) were used to evaluate blood metabolite concentrations before and after a lipopolysaccharide (LPS) challenge. On d 63, heifers were fitted with jugular catheters and moved into individual stalls. On d 64, heifers were intravenously challenged with LPS (0.5 μg/kg BW), and blood samples were collected every 0.5 h from –2 to 8 h and at 24 h relative to the LPS challenge (0 h). Serum glucose, serum urea nitrogen (SUN), and NEFA concentrations were determined. Cattle lost less weight at both 24 and 72 h after the LPS challenge with increasing DCP percentage (P \u3c 0.01). Glucose (P = 0.12) and NEFA (P = 0.13) concentrations did not differ before the LPS challenge; however, there was a treatment effect for SUN, with elevated concentrations of SUN in CON cattle (P \u3c 0.01). After the LPS challenge, DCP-fed cattle had reduced glucose, elevated NEFA, and reduced SUN concentrations (P ≤ 0.01). Results indicate that dietary DCP modulated metabolite concentrations in heifers following an endotoxin challenge and affected feedlot performance when incorporated in receiving diets in replacement of corn. Future studies will need to address strategies to increase DMI or explore levels of DCP less than 10% in the diet of newly received heifer calves