The Effects of a Blend of Essential Oils on Rumen Efficiency of Lactating Dairy Cows

The objective of this study was to evaluate the effects of SS a blend of commercially available essential oils (EO) on rumen microbial efficiency and kinetics, and consequently, effects on production parameters of dairy cows fed a low-starch diet and in vitro analysis of varying doses of SS on ruminal fermentation at different stages of lactation. The study consisted of two experiments, the in vivo Experiment 1, was conducted on a commercial robotic dairy in southwest Minnesota outfitted with two Lely Astronaut A4robotic milking units (Goter’s Clay & Dairy Equipment of MN, INC., Pipestone, MN). One hundred-seven Holstein cows were randomly assigned to either the control diet (CON) (25% starch) or the low-starch (LS) diet (22% starch) in a randomized complete block design (RCBD), where cows were blocked by body weight (BW) and body condition score (BCS). All cows were fed 28g/hd/d of SS throughout the trial. The experiment included 14 d of dietary adaptation and 28 d of data collection. A tendency for higher pellet intake was observed for the LS treatment. Milk production, fat, and protein yield were similar among treatments. Total volatile fatty acid concentrations were similar between treatments, with a tendency observed for an increase in acetate percentage for the LS treatment. BUN and MUN concentrations were similar between treatments, ammonia concentrations were significantly lower for LS (5.84 vs. 9.69mM), and pH values tended to be higher for LS treatment. In Experiment 2, an in vitro analysis was carried out as a 2 × 3 factorial arrangement of treatments with two doses (i.e., single and double) of SS and rumen fluid (RF) from Holstein cows at three stages of lactation (i.e., early, mid, and late). The latter was done with the aim to evaluate the effects of EO at different stages of lactation on ruminal fermentation characteristics and kinetics. Each treatment was replicated in 3 gas fermentation bottles plus a control treatment with RF only, and 3 batches containing all treatments were repeated 3 times on different days. RF was collected from 9 lactating multiparous cows (n = 3/group) at early [days in milk (DIM) 32-36], mid (DIM 144-157), and late (DIM 277-290) stages of lactation via esophageal tube at approximately 4 h after feeding. Gas production was significantly lower with the addition of the double dose of SS, but no treatment differences were observed. Total VFA concentrations were similar among treatments. Propionate percentage was significantly greater for the early lactation and single dose of SS treatment. Acetate: propionate ratio was significantly greater for the late lactation, and both single and double dose of SS. Ammonia concentrations were significantly lower in the early lactation and single dose of SS treatment, and early, mid and late lactation and double dose with mid lactation having the greatest concentration and early lactation having the lowest concentration. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were not affected by experimental treatment effects

Transcriptional changes detected in fecal RNA of neonatal dairy calves undergoing a mild diarrhea are associated with inflammatory biomarkers

<div><p>After birth, a newborn calf has to adapt to an extrauterine life characterized by several physiological changes. In particular, maturation of the gastrointestinal tract in a new environment loaded with potential pathogens, which can predispose neonatal calves to develop diarrhea, and is a major cause of morbidity and mortality during the first 4 wks of life. We aimed to investigate the inflammatory adaptations at a transcriptomic level in the gastrointestinal (GI) tract to a mild diarrhea in neonatal dairy calves using RNA isolated from fresh fecal samples. Eight newborn Jersey male calves were used from birth to 5 wks of age and housed in individual pens. After birth, calves received 1.9 L of colostrum from their respective dams. Calves had ad-libitum access to water and starter grain (22% CP) and were fed twice daily a total of 5.6 L pasteurized whole milk. Starter intake, body weight (BW), fecal score, withers height (WH), and rectal temperature (RT) were recorded throughout the experiment. Blood samples were collected weekly for metabolic and inflammatory profiling from wk 0 to wk 5. Fresh fecal samples were collected weekly and immediately flash frozen until RNA was extracted using a Trizol-based method, and subsequently, an RT-qPCR analysis was performed. Orthogonal contrasts were used to evaluate linear or quadratic effects over time. Starter intake, BW, and WH increased over time. Fecal score was greatest (2.6 ± 0.3) during wk 2. The concentrations of IL-6, ceruloplasmin, and haptoglobin had a positive quadratic effect with maximal concentrations during wk 2, which corresponded to the maximal fecal score observed during the same time. The concentration of serum amyloid A decreased over time. The mRNA expression of the proinflammatory related genes <i>TLR4</i>, <i>TNFA</i>, <i>IL8</i>, and <i>IL1B</i> had a positive quadratic effect of time. A time effect was observed for the cell membrane sodium-dependent glucose transporter <i>SLC5A1</i>, for the major carbohydrate facilitated transporter <i>SLC2A2</i>, and water transport function <i>AQP3</i>, where <i>SLC5A1</i> and <i>AQP3</i> had a negative quadratic effect over time. Our data support the use of the fecal RNA as a noninvasive tool to investigate intestinal transcriptomic profiling of dairy calves experiencing diarrhea, which would be advantageous for future research including nutritional effects and health conditions.</p></div

Target genes and their biological function.

<p>Target genes and their biological function.</p

Profiles of energy (Glucose and BHBA) and muscle mass catabolism (Creatinine and urea) metabolites in blood during the neonatal period in Jersey dairy calves.

<p>The time effect (<i>P</i>< 0.10) was further analyzed through orthogonal contrast in order to determine linear (L) and quadratic (Q) effects over time. Values are means, with standard errors represented by vertical bars.</p

Performance parameters during the neonatal period of Jersey calves.

<p>Starter intake (A), fecal scores (B), withers height (C), body weight (D), and average daily gain (ADG) (E). The <i>P</i> values for main effect of time are shown in each plot. The time effect (<i>P</i>< 0.10) was further analyzed in starter intake and fecal scores through orthogonal contrast in order to determine linear (L) and quadratic (Q) effects over time. Values are means, with standard errors represented by vertical bars.</p

Profiles of liver function [albumin, cholesterol, total bilirubin, gamma-glutamyl transferase (GGT), paraoxonase (PON), glutamic-oxaloacetic transaminase (GOT)] metabolites in blood during the neonatal period of Jersey dairy calves.

<p>The time effect (<i>P</i>< 0.10) were further analyzed through orthogonal contrast in order to determine linear (L) and quadratic (Q) effects over time. Values are means, with standard errors represented by vertical bars.</p

Profiles of inflammatory response (haptoglobin, ceruloplasmin, IL-6, SAA, and IL-1β) biomarkers in blood during the neonatal period in Jersey dairy calves.

<p>The time effect (<i>P</i>< 0.10) were further analyzed through orthogonal contrast in order to determine linear (L) and quadratic (Q) effects over time. An overall trend for an increase (<i>P</i> ≤ 0.08) in IL-1β at wk 1 in comparison to wk 0, 2, 3, and 4 was denoted by an asterisk (*). Values are means, with standard errors represented by vertical bars.</p

Expression of genes related to the activation of the innate immune system (<i>TLR2</i> and <i>TLR4</i>) and pro-inflammatory response (<i>NFKB1</i>, <i>TNFA</i>, <i>IL1B</i>, <i>IL8</i>, and <i>IFNG</i>) in fecal samples collected during the neonatal period of Jersey calves.

<p>The time effect (<i>P</i>< 0.10) were further analyzed through orthogonal contrast in order to determine linear (L) and quadratic (Q) effects over time. Values are means, with standard errors represented by vertical bars.</p

Profiles of oxidative stress [reactive oxygen metabolites (ROM) and ferric reducing antioxidant power (FRAP)] biomarkers in blood during the neonatal period in Jersey calves.

<p>The time effect (<i>P</i> < 0.10) were further analyzed through orthogonal contrast in order to determine linear (L) and quadratic (Q) effects over time. Values are means, with standard errors represented by vertical bars.</p

Expression of genes coding for proteins involved in ions (<i>SLC5A1</i>, <i>SLC2A2</i>) and water (<i>AQP3</i>) transporters, in fecal samples collected during the neonatal period of Jersey calves.

<p>The time effect (<i>P</i> < 0.10) were further analyzed through orthogonal contrast in order to determine linear (L) and quadratic (Q) effects over time. The <i>P</i> values for main effect of time are shown in each plot. Values are means, with standard errors represented by vertical bars.</p