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The use of cereals as forage crops is limited due to the high lignin content in the cell walls reducing nutrient digestibility. Recent research has focused on reducing lignification in forage crops through gene mutations. This study investigated the ruminal fermentation characteristics of a barley mutation (orange lemma), which is associated with a lower lignin content, using the in vitro ruminal fermentation system (RUSITEC). Two-rowed spring barley cv. ‘Optic’ and its ethyl methane sulfonate (EMS)-induced orange lemma (rob1) mutant line were harvested at both stem elongation and early fruit development and incubated in the RUSITEC system. Gas production, concentrations of short-chain fatty acids (SCFA) and ammonia and the nutrient degradation of the plants after 48 h incubation were investigated. Additional samples were analysed for microbial composition using MiSeq sequencing technology. In general, acid detergent lignin (ADL) was higher at early grain filling than stem elongation. ADL was lower in the mutant line than in the wild type at both stem elongation (13.9% vs 18.5%) and early grain development (26.0% vs 28.6%; dry matter basis). This was reflected in increased ruminal degradation of neutral detergent fibre (61.7% vs 53.7%; P < 0.001) when harvested at stem elongation, but not at the later stage. In contrast, methane formation was lower with rob1 than ‘Optic’ (P = 0.002), especially when harvested at stem elongation. No difference was seen in protein degradation between the barley genotypes. The fermentation SCFA profile did not differ between barley genotypes when harvested at stem elongation, but at early fruit development more acetate and less butyrate was produced with rob1. Microbial species richness was lower when barley was incubated at stem elongation compared to fruit development (P < 0.001), which was especially pronounced with rob1 (P = 0.026). The abundance of Bacteroidetes, Synergistetes and Tenericutes was lower when plants harvested at early grain development were incubated compared to the stem elongation stage, whereas the abundance of Cyanobacteria, Elusimicrobia, Fusobacteria, Lentisphaerae, Proteobacteria, Verrucomicrobia and WPS-2 was higher (P < 0.001). In conclusion, most fermentation parameters were affected by vegetation stage and related changes in nutrient composition. However, additional effects of barley genotype were seen on the rumen microbial community structure, SCFA profile and methane production.

Several feed efficiency (FE) metrics are currently used in livestock production to select for improved FE. Whether or not different FE metrics similarly estimate physiological characteristics in chickens of diverging FE has not been reported so far. This study aimed to assess potential differences in feed intake (FI), performance, and nutrient excretion in broiler chickens of diverging FE when ranked according to their residual FI (RFI), residual BW gain (RBG), RFI and BW gain (RIG), and G:F between d 7 and 35 of life. The FI was determined daily and BW was recorded once a week. The ranking of chickens into good, medium, and poor FE groups was completed separately for each FE metric. Freshly dropped excreta were collected for pH and DM measurements on d 30 to 32 of life and total excreta for determination of nutrient excretion was collected on d 34 to 36 of life. Relationships among FE metrics were evaluated using regression analysis showing that RFI, RIG, and G:F were more related to each other than to RBG. The FE values greatly varied among chickens for all FE metrics and chickens did not always cluster within the same FE group when using RFI, RIG, RBG, and G:F as the FE metrics because of the calculation approaches. Due to sex-related differences in performance, data of male and female chickens were analyzed separately. The RFI and RIG metrics showed a linear increase (P< 0.01) in total FI from good to poor FE in male and female chickens, whereas G:F showed this effect (P≤ 0.011) only when BW gain was standardized to 1,500 g. The RBG did not clearly select chickens of enhanced total BW gain and only tended (P< 0.1) to select for greater BW gain from good to poor FE in female chickens. Excreta pH linearly decreased by 0.7 log units and DM content increased in males from good to poor FE when using RFI and RIG, respectively (P< 0.01). In both sexes, RFI (P< 0.05) and RIG metrics (P≤ 0.06) showed a linear increase in daily nitrogen excretion from good to poor FE. In conclusion, results demonstrate that selection of the metric used to determine the FE of chickens modified the results obtained for comparison of production parameters and nutrient excretion among FE groups. Thereby, the RFI, RIG, and G:F metrics were beneficial in selecting the most feed efficient chickens to reduce feed costs, whereas the use of RFI and RIG may be better to select chickens with improved nitrogen retention and thus reduced excretion of an environmental pollutant.

The objective of this study was to investigate the effect of the pattern of concentrate-rich feeding on subacute ruminal acidosis (SARA), its severity, and the corresponding changes in VFA concentration. Eight rumen-cannulated Holstein cows were assigned to a 2 × 2 crossover design with 2 SARA challenge models and 2 experimental runs (n= 8 per treatment). Each run lasted for 40 d, consisting of a 6-d baseline, a 6-d gradual grain adaptation, and a 28-d SARA challenge period. The 2 SARA challenge models were transient (TRA) and persistent (PER) SARA. Initially, all cows were subjected to a forage-only diet (baseline) and gradually switched to 60% concentrate (DM basis). Then, cows in the PER model were continuously challenged for 28 d, whereas cows in the TRA model had a 7-d break from the SARA diet and were fed the forage-only diet after the first 7 d of SARA challenge. Thereafter, the TRA cows were rechallenged with the SARA diet. Wireless ruminal pH sensors were used to obtain ruminal pH profiles and temperature over the experimental period. For the determination of VFA, free ruminal liquid (FRL) and particle-associated ruminal liquid (PARL) were collected once for the baseline and twice (d 20 and 40 for the PER model) or 3 times (d 13, 30, and 40 for the TRA model) during SARA, each time at 0, 4, and 8 h after the morning feeding. Cows in both models experienced SARA albeit with day-to-day variation. From the start until the first 7-d SARA, cows of both models had similar pH profiles, but during the rechallenge, SARA was more severe in the TRA model than in the PER model based on lower daily mean ruminal pH (5.93 vs. 6.15; SEM 0.058) and double the amount of time at pH < 5.8 (497 vs. 278 min; SEM 68.61, P< 0.05). Mean ruminal temperature was raised during SARA compared with the baseline (38.9 vs. 38.7°C; SEM 0.057, P< 0.001). Concentrations of VFA increased with increasing time after feeding (P< 0.001). In general, SARA challenge (d 40 vs. the baseline), but not the challenge model, altered VFA concentrations and profile of both FRL and PARL by increasing the amounts of propionate and butyrate, whereas total VFA concentration was less affected. Proportions of VFA shifted over the duration of SARA challenge with more propionate but less acetate and butyrate proportions with advancing days of SARA challenge, leading to the values of the last SARA day being different from the earlier days (P< 0.05). In conclusion, the TRA condition led to the higher severity of SARA, but factors beyond feed intake and VFA alterations seemed to play a role.

The aim of this study was to evaluate the accuracy and precision of indwelled wireless sensors relative to intrareticuloruminal differences in dairy cows transitioned from a forage to a high-concentrate diet. A feeding trial was performed with 8 rumen-cannulated Holstein cows. The cows were stepwise switched from 0 to 60% concentrate in the diet and fed 5 wk. Samples from the free ruminal liquid (FRL) from the ventral rumen and from the particle-associated ruminal liquid (PARL) in the rumen mat were manually taken at 0, 4, and 8 h after the morning feeding on d 0, 7, 14, and 34 of the experiment through the ruminal cannula to measure pH in FRL and PARL using a pH electrode. Additionally indwelling reticular wireless pH sensors were used to measure reticular pH every 10 min throughout the experiment. Precision and accuracy properties as a measure of reproducibility of the methods were statistically evaluated. Data showed significant differences among pH readings of indwelling sensors and pH measurements taken by means of a conventional electrode in both FRL and PARL (P< 0.05). These differences became more evident when 60% concentrate diet was fed. Across all experimental days, the pH of the FRL was greatest and the pH reported by indwelling sensors intermediate, whereas the pH of PARL was lowest. The concordance correlation coefficient (CCC) analysis revealed a high agreement between indwelling sensors and FRL (CCC = 0.709) but a low agreement with the pH of PARL (CCC = 0.495). In conclusion, the study indicated that wireless sensors can satisfactorily reflect the pH of FRL but poorly reflect that of PARL.

Emerging evidence at the mRNA level indicates that feeding high-grain diets to ruminants leads to coordinated changes in the molecular response of the rumen epithelium. Yet, epithelial adaptation of the hindgut to increasing dietary grain levels has not been established in ruminants. Therefore, the objective of this study was to characterize alterations in mRNA expression associated with nutrient transport and electrochemical gradients in rumen and colon epithelium, and rumen morphology in growing goats fed different grain levels. Goats (n = 6) were fed diets with increasing levels of 0, 30, or 60% barley grain for 6 wk. Goats were euthanized 2 h after their last feeding, and digesta and tissue samples of the cranial part of the ventral rumen and proximal colon were collected. Goats fed the 60% grain diet exhibited a lower ruminal and colonic pH (P < 0.01) and a greater colonic total VFA concentration (P < 0.05) compared with those fed the 0 and 30% grain diets. As response to the decreased ruminal pH, goats fed the 60% grain diet had a greater (P < 0.05) keratinization and thicker stratum corneum of the rumen epithelium than goats fed the 0 and 30% grain diets. The 60% grain diet upregulated (P < 0.05) MCT1 expression by 45% and downregulated (P < 0.05) the expression of MCT4 and SGLT1 by 28 and 50%, respectively, in rumen epithelium compared with the 0 and 30% grain diets. Accordingly, goats fed the 60% grain diet had a greater (P < 0.05) expression of MCT1 and ATP1A1 in colon epithelium than goats fed the 0 and 30% grain diets. Regression analyses showed negative relationships (R(2) = 0.35 to 0.87, P < 0.05) of MCT1 and ATP1A1 expression in rumen and colon epithelium and thickening of ruminal stratum corneum to decreasing luminal pH values, suggesting greater mRNA expression at lower pH. In contrast, MCT4 expression in rumen epithelium positively correlated to luminal pH (R(2) = 0.95, P < 0.01). In conclusion, results of this model study indicated that with the greatest grain level rumen and colon molecular epithelial responses may have been related to counteract the consequences of luminal acidification on intracellular homeostasis in epithelial cells and concomitantly to increase systemic absorption of VFA.

Cereal β-glucan may be detrimental in pig production because of negative effects on nutrient digestibility, but they may act as functional ingredients by stimulating the intestinal microbiota. This study primarily aimed to investigate relations between dietary β-glucan and nutrient digestibility, intestinal fermentation, and manure NH3 emission in weaned, growing, and finishing pigs. Effects of dietary xylose, NDF, and CP, and pig BW on animal responses were also evaluated. A meta-analytical approach, accounting for inter- and intraexperiment variations, was used to compute prediction models. Data from 26 studies including 107 different dietary treatments with appropriate dietary and physiological measurements were used to parameterize these models. Dietary β-glucan inclusion ranged from 0 to 6.7%. Increasing dietary β-glucan reduced apparent ileal (AID) and total tract digestibility (ATTD) of CP and energy (R(2) = 0.12 to 0.29; P < 0.05), whereas the ATTD of DM was reduced by 10% up to a threshold β-glucan of 3.5%, above which the response became asymptotic (R(2) = 0.34; P < 0.01). Increasing dietary NDF content decreased ATTD of DM and energy, and increasing xylose concentration reduced ATTD of energy and CP (R(2) = 0.24 to 0.85; P < 0.05). Broken-line model indicated that cecal total VFA and butyrate concentrations increased up to a threshold of 2.5 and 1.4% β-glucan in the diet, respectively, above which these responses became asymptotic (R(2) = 0.77 to 0.96; P < 0.05). Ileal butyrate was negatively and colonic iso-butyrate was positively linked to increasing β-glucan concentration (R(2) = 0.17 to 0.41; P < 0.05). Greater β-glucan concentration were negatively related (R(2) = 0.86; P < 0.01) to NH3 emission, indicating a reduction in NH3 emission by one-half with 6% β-glucan. Backward elimination analysis indicated that greater BW of pigs counteracted (P < 0.05) the negative effect of β-glucan on AID of CP and energy and ATTD of DM and CP. Pig BW also enhanced effects of β-glucan on cecal total VFA, colonic iso-butyrate, ileal butyrate, and NH3 emission (P < 0.05). Dietary CP potentiated (P < 0.01) the β-glucan effects on cecal total VFA, cecal butyrate, and colonic iso-butyrate. In conclusion, this study indicates that β-glucan can stimulate cecal butyrate and ameliorate manure NH3 emission, thereby decreasing nutrient digestibility. Because greater BW ameliorates β-glucan effects, finishing diets may be formulated to contain more β-glucan than weaner diets.

The present study aimed at investigating the effects of essential oils and their bioactive compounds (EOBC) on rumen fermentation in vivo as well as animal performance and feed efficiency in different ruminant species, using a meta-analysis approach. Ruminant species were classified into 3 classes consisting of beef cattle, dairy cattle, and small ruminants. Two datasets (i.e., rumen fermentation and animal performance) were constructed, according to the available dependent variables within each animal class, from 28 publications (34 experiments) comprising a total of 97 dietary treatments. In addition, changes in rumen fermentation parameters relative to controls (i.e., no EOBC supplementation) of all animal classes were computed. Data were statistically analyzed within each animal class to evaluate the EOBC dose effect, taking into account variations of other variables across experiments (e.g., diet, feeding duration). The dose effect of EOBC on relative changes in fermentation parameters were analyzed across all animal classes. The primary results were that EOBC at doses <0.75 g/kg diet DM acted as a potential methane inhibitor in the rumen as a result of decreased acetate to propionate ratio. These responses were more pronounced in beef cattle (methane, P = 0.001; acetate to propionate ratio, P = 0.005) than in small ruminants (methane, P = 0.068; acetate to propionate ratio, P = 0.056) and in dairy cattle (P > 0.05), respectively. The analysis of relative changes in rumen fermentation variables suggests that EOBC affected protozoa numbers (P < 0.001) but only high doses (>0.20 g/kg DM) of EOBC had an inhibitory effect on this variable whereas lower doses promoted the number. For performance data, because numbers of observations in beef cattle and small ruminants were small, only those of dairy cattle (DMI, milk yield and milk composition, and feed efficiency) were analyzed. The results revealed no effect of EOBC dose on most parameters, except increased milk protein percentage (P< 0.001) and content (P = 0.006). It appears that EOBC supplementation can enhance rumen fermentation in such a way (i.e., decreased acetate to propionate ratio) that may favor beef production. High doses of EOBC do not necessarily modify rumen fermentation or improve animal performance and feed efficiency. Furthermore, additional attention should be paid to diet composition and supplementation period when evaluating the effects of EOBC in ruminants.

This study investigated the effects of feeding barley grain treated with lactic acid (LA) and heat on the profile of plasma metabolites related to carbohydrate and lipid metabolism and variables related to rumen health and acute phase response. Eight primiparous rumen-fistulated lactating Holstein cows were randomly assigned, in a crossover design, to 1 of the 2 dietary treatments consisting of 32% (DM basis) rolled barley grain steeped in an equal quantity of either tap water alone (CTR) or a 1.0% LA solution and heated at 55°C for 48 h (LAH). Each experimental period was 21 d, with the last 10 d used for measurements. Blood samples were collected on d 1, 3, 5, 7, 9, and 11 before the morning feeding and on the last day of each period at 0, 2, 4, 6, 8, 10, and 12 h postfeeding to measure glucose, lactate, cholesterol, beta-hydroxybutyrate (BHBA), NEFA, haptoglobin (Hp), serum amyloid A (SAA), and tumor necrosis factor-alpha (TNF-α). Also, rumen samples were collected on d 1, 5, and 11 as well as at 0, 4, 8, and 12 h postfeeding on the last day of each period for measuring the concentration of rumen endotoxin. Results of the day-to-day analysis indicated that cows fed the LAH diet had reduced preprandial concentrations of rumen endotoxin (472 vs. 793 ng/mL; P < 0.01) and cholesterol and greater lactate in the plasma; however, treatment had no effect on plasma Hp and TNF-α (P > 0.10). Postprandial responses showed that the LAH diet tended to decrease the concentration of SAA (4.67 vs. 8.50 μg/mL; P = 0.06). Also, there was a treatment by time interaction for rumen endotoxin (P < 0.01), suggesting a role for both the treatment and the time of sampling on this variable. Furthermore, greater concentration of BHBA and a tendency for greater NEFA and reduced concentrations of plasma glucose were observed in cows fed the LAH diet. In conclusion, results indicated that feeding dairy cows barley grain steeped in 1.0% LA and treated with heat modulated the profile of plasma metabolites and acute phase response.

The objective of this investigation was to determine associations among rumen endotoxin, plasma serum amyloid A (SAA), and C-reactive protein (CRP) with plasma Ca, Fe, Zn, and Cu in lactating cows challenged with graded amounts of rolled barley grain in the diet (i.e., 0, 15, 30, and 45% of DMI). Correlative relationships among variables were determined by linear and nonlinear regression procedures adjusted for the effects of day, animal, and experimental period. Increasing the amount of grain in the diet was successful in inducing an acute phase response, as assessed by augmentation of rumen endotoxin and plasma CRP and SAA (P< 0.01). The correlative analysis revealed inverse, nonlinear relationships of rumen endotoxin and plasma SAA with circulating Ca. Interestingly, plasma Ca reached the asymptotic plateau at 10.6 mg/dL. The increase in rumen endotoxin was associated with an abrupt decrease in plasma Fe (R2= 0.91; P< 0.001). A similar relationship, although at a reduced estimation accuracy (R2= 0.21; P< 0.01), was observed between rumen endotoxin and plasma Zn. Augmentation of rumen endotoxin and plasma CRP resulted in a positive, biphasic response of plasma Cu. In conclusion, the increase in rumen endotoxin in response to high-grain diets, and the resulting increases in plasma SAA and CRP, were strongly correlated with fluctuations of plasma minerals. Results suggest that new feeding strategies should be developed to curb the release of endotoxin in the rumen fluid to prevent perturbing minerals in the plasma.

The objective of this investigation was to study the effects of feeding backgrounding and finishing diets on selected acute phase proteins in the plasma of feedlot steers. Two groups of 12 steers each, at the backgrounding and finishing stages, were offered either a backgrounding (45% barley grain-based concentrate and 55% barley silage on a DM basis) or a finishing (91% barley grain-based concentrate and 9% barley silage) diet for 12 and 15 wk, respectively. Steers at the backgrounding and finishing stages had initial BW of approximately 250 and 380 kg, respectively, at the beginning of the experiment. Blood samples were obtained from a jugular vein at 3-wk intervals during the experimental period beginning at wk 3 or 0 for the backgrounding and finishing periods, respectively. Plasma samples were analyzed for serum amyloid A (SAA), lipopolysaccharide-binding protein (LBP), haptoglobin, and ケ1-acid glycoprotein. Steers fed the finishing diet showed peak plasma SAA, LBP, and haptoglobin within 3 wk from the initiation of the diet (20, 23, and 1,940 μg/mL for SAA, LBP, and haptoglobin, respectively). Although plasma ケ1-acid glycoprotein reached a peak concentration (449 μg/mL) at the beginning of the finishing phase, no diet effect was obtained for this variable. Steers fed the backgrounding diet showed less variation in the concentrations of plasma acute phase proteins measured; plasma haptoglobin reached a peak concentration (1,720 μg/mL) 9 wk after the beginning of this diet. In conclusion, feeding feedlot steers the backgrounding or finishing diet was associated with increased peak concentrations of acute phase proteins in the plasma. More research is warranted to elucidate the mechanisms behind the inflammatory responses observed in feedlot steers and their implications for health issues and the production efficiency of feedlot operations.