High-concentrate Diet Research Articles

A high-concentrate diet induces inflammatory injury via regulating Ca2+/CaMKKβ-mediated autophagy in mammary gland tissue of dairy cows.

Calmodulin-dependent protein kinase β (CaMKKβ) is closely related to Ca2+ concentration. An increase in Ca2+ concentration in the cytoplasm activates CaMKKβ, and activated CaMKKβ affects the activities of AMPK and mTOR and induces autophagy. A high-concentrate diet leads to Ca2+ disorder in mammary gland tissue. Therefore, this study mainly investigated the induction of mammary gland tissue autophagy by a high-concentrate diet and the specific mechanism of lipopolysaccharide (LPS)-induced autophagy in bovine mammary epithelial cells (BMECs). Twelve mid-lactation Holstein dairy cows were fed with a 40% concentrate diet (LC) and a 60% concentrate diet (HC) for 3 weeks. At the end of the trial, rumen fluid, lacteal vein blood, and mammary gland tissue were collected. The results showed that the HC diet significantly decreased rumen fluid pH, with a pH lower than 5.6 for more than 3 h, indicating successfully induction of subacute rumen acidosis (SARA). The mechanism of LPS-induced autophagy in BMECs was studied in vitro. First, the cells were divided into a Ctrl group and LPS group to study the effects of LPS on the concentration of Ca2+ and autophagy in BMECs. Then, cells were pretreated with an AMPK inhibitor (compound C) or CaMKKβ inhibitor (STO-609) to investigate whether the CaMKKβ-AMPK signaling pathway is involved in LPS-induced BMEC autophagy. The HC diet increased the concentration of Ca2+ in mammary gland tissue and pro-inflammatory factors in plasma. The HC diet also significantly increased the expression of CaMKKβ, AMPK, and autophagy-related proteins, resulting in mammary gland tissue injury. In vitro cell experiments showed that LPS increased intracellular Ca2+ concentration and upregulated protein expression of CaMKKβ, AMPK, and autophagy-related proteins. Compound C pretreatment decreased the expression of proteins related to autophagy and inflammation. In addition, STO-609 pretreatment not only reversed LPS-induced BMECs autophagy but also inhibited the protein expression of AMPK, thereby alleviating the inflammatory response in BMECs. These results suggest that inhibition of the Ca2+/CaMKKβ-AMPK signaling pathway reduces LPS-induced autophagy, thereby alleviating inflammatory injury of BMECs. Therefore, SARA may increase the expression of CaMKKβ by increasing Ca2+ levels and activate autophagy through the AMPK signaling pathway, thereby inducing inflammatory injury in mammary gland tissue of dairy cows.

Comparison of the Effect of using Chemical Buffer and Acid-Consuming Bacteria on Digestibility and Fermentation, Growth Performance and Meat Quality of Lambs Fed with High Concentrate Diets

Comparison of the Effect of using Chemical Buffer and Acid-Consuming Bacteria on Digestibility and Fermentation, Growth Performance and Meat Quality of Lambs Fed with High Concentrate Diets

Effects of High Concentrate-Induced Subacute Ruminal Acidosis Severity on Claw Health in First-Lactation Holstein Cows.

This study aimed to evaluate the effects of diet-induced subacute rumen acidosis (SARA) severity during transition and the early lactation period on claw health in 24 first-lactation Holstein heifers. All heifers were fed a 30% concentrate (in dry matter) close-up ration three weeks before calving, then switched to a high-concentrate ration (60% dry matter), which was fed until the 70th day in milk (DIM) to induce SARA. Thereafter, all cows were fed the same post-SARA ration with around 36% concentrate in dry matter. Hoof trimming was performed before calving (visit 1), at 70 (visit 2) and at 160 DIM (visit 3). All claw lesions were recorded, and a Cow Claw Score (CCS) was calculated for each cow. Locomotion scores (LCS 1-5) were assessed at two-week intervals. Intraruminal sensors for continuous pH measurements were used to determine SARA (pH below 5.8 for more than 330 min in 24 h). The cluster analysis grouped the cows retrospectively into light (≤11%; n = 9), moderate (>11-<30%; n = 7), and severe (>30%; n = 8) SARA groups, based on the percentage of days individual cows experienced SARA. Statistically significant differences were found between SARA groups light and severe in terms of lameness incidence (p = 0.023), but not for LCS and claw lesion prevalence. Further, the analysis of maximum likelihood estimates revealed that for each day experiencing SARA, the likelihood of becoming lame increased by 2.52% (p = 0.0257). A significant increase in white line lesion prevalence was observed between visits 2 and 3 in the severe SARA group. The mean CCS in severe SARA group cows were higher at each visit compared to cows in the other two groups, but without statistical significance. Overall, this is the first study indicating that first-lactation cows fed a similar high-concentrate diet but with a higher severity of SARA tended to have poorer claw health, albeit with only partial statistical evidence.

Inclusion of licuri cake in high-grain diets for steers: Intake, digestibility, carcass characteristics, and meat quality

A high-grain diet is essential to maximize growth and yield as well as to provide high-quality meat in beef cattle. This study evaluated the effects of including licuri cake in high-grain diets for steers on performance and carcass and meat quality. Forty-four crossbred (1/2 Bos taurus × 1/2 Bos indicus) castrated steers at 24 months of age, with an initial weight of 358.19 ± 41.57 kg, were used. The animals were distributed into four treatments that consisted of diets including licuri cake (0, 85, 170, or 255 g/kg, dry matter basis). Dry matter intake and digestibility decreased with the inclusion of licuri cake in the diet. However, the addition of the ingredient did not influence the intakes of total digestible nutrients (6.7 ± 0.5 kg/day) or crude protein. Licuri cake inclusion did not influence weight gain (1.5 ± 0.2 kg/day) or hot carcass weight (255.1 ± 24.9 kg). There was also no effect on carcass fat thickness, whereas the cholesterol content in the meat decreased with the addition of the cake. We recommend the inclusion of up to 255 g/kg licuri cake in the diet of feedlot steers fed high-concentrate diets.

Wet brewers’ grains as a source of protein for feedlot lambs: Impacts on intake, apparent nutrient digestibility, ruminal fermentation, and nitrogen balance

The aim of this study was to evaluate the effect of wet brewers’ grain (WBG) as an alternative ingredient replacing soybean meal (SBM) and ground corn (GC) on nutrient intake and apparent digestibility, ruminal fermentation characteristics, and nitrogen balance in feedlot lambs. Five ruminally cannulated ½ Dorper × ½ Santa Inês lambs, castrated with 48.3 ± 2.0 kg of initial BW and 8.3 ± 0.68-month-old (mean ± SD), were assigned in a 5 × 5 Latin square design. The experimental diets were composed of 10% roughage (Coastcross hay) and 90% concentrates, in which 85.9% of the diet was composed of GC (71.3%) plus SBM (14.6%) in the control diet. Treatments consisted in WBG inclusion levels of 7.6%, 15%, 23% and 30% replacing GC+SBM in control diet with the aim to maintain isonitrogenous concentrations. The data were analyzed using a linear or quadratic polynomial contrast in SAS. There was no effect of WBG inclusion on DMI, OM nor CP intake, but a linear increase was observed for NDF (P < 0.001), ADF (P < 0.001), EE intake (P < 0.01), and linear decrease (P < 0.001) on NFC intake. Inclusion of WBG decrease linearly NFC, while DM, OM, and CP digestibility were being lower for lambs fed a diet contained 23% WBG (quadratic component, p < 0.05). The replacement of SBM and corn grain by WBG, linearly increased the molar ratio of acetate (P < 0.01), and linearly decreased propionate (P < 0.01), resulting in a linear increase in the acetate:propionate ratio (P = 0.04). In addition, increasing the inclusion of WBG linearly increased the molar proportion of isovalerate (P < 0.05). Ruminal pH increased linearly (P < 0.001) by dietary WBG inclusion, as consequence, ruminal pH was maintained less time below 5.5 as WBG inclusion increased. Although nitrogen excretion was greater with 23% inclusion of WBG in diet (quadratic component, P < 0.05), there was no effect (P > 0.10) on retained N. Based on diet acceptability, digestibility, N retention, and ruminal fermentation parameters, it is concluded that, WBG can be used as feed ingredient up to 7.6% in diets, replacing partially SBM and GC in finishing diets for lambs. Inclusion WBG replacing SBM and partially GC, minimize the risk of acidosis in lambs fed high-concentrate diets during fattening. Inclusions beyond 23% decreased significant diet digestibility and increased ruminal acetate: propionate molar ratio, decreasing energy efficiency, increasing methane losses.

Effects of dietary disodium fumarate supplementation on muscle quality, chemical composition, oxidative stress and lipid metabolism of Hu sheep induced by high concentrate diet

Long-term feeding of high-concentrate (HC) diet causes the decrease of rumen pH, and induces subacute rumen acidosis (SARA), which results in metabolic disorders in sheep. This not only reduces animal performance, but also increases the risk of oxidative stress and inflammatory reaction. Disodium fumarate can improve the rumen buffering capacity and increase rumen pH. This experiment was conducted to investigate the effects of high concentrate diet on muscle quality, chemical composition, oxidative damage and lipid metabolism of Hu sheep, and the regulating effect of disodium fumarate. The results showed that HC diet induced SARA by reducing rumen pH value, thus causing oxidative stress and lipid metabolism disorder in longissimus lumborum (LL) muscle of Hu sheep, which also reduced meat quality by increasing shear force, drip loss, cooking loss, chewiness and hardness, and reducing the contents of crude fat and crude protein in LL muscle. However, disodium fumarate can improve meat quality of SARA Hu sheep by regulating rumen pH, inhibiting muscle oxidative stress and promoting lipid metabolism.

Shortening the adaptation of Nellore cattle to high-concentrate diets using only virginiamycin as sole feed additive negatively impacts ruminal fermentation and nutrient utilization.

Feedlot cattle are usually adapted to high-concentrate diets containing sodium monensin (MON) in more than 14 days. However, considering that the dry matter intake DMI is usually lower during adaptation when compared to the finishing period, the use of MON during adaptation may decrease even further the DMI, and virginiamycin (VM) may be an alternative. This study was designed to investigate the effects of shortening the adaptation length from 14 to 9 or 6 days on ruminal metabolism, feeding behavior, and nutrient digestibility of Nellore cattle fed high-concentrate diets containing only VM as the sole feed additive. The experimental design was a 5 × 5 Latin square, where each period lasted 21 days. Five 17 mo-old Nellore yearling bulls were used (415 ± 22 kg of body weight), which were assigned to five treatments: (1) MON (30 mg/kg) and adaptation for 14 days; (2) MON (30 mg/kg) + VM (25 mg/kg) and adaptation for 14 days; (3) VM (25 mg/kg) and adaptation for 14 days; (4) VM (25 mg/kg) and adaptation for 9 days, and (5) VM (25 mg/kg) and adaptation for 6 days. A quadratic effect for adaptation length when only VM was fed was observed for mean pH (P = 0.03), duration of pH below 5.2 (P = 0.01) and 6.2 (P = 0.01), where cattle consuming VM adapted for 9 days had higher mean pH and shorter period of pH below 5.2 and 6.2. Cattle that consumed only MON had a lower concentration of butyrate (P = 0.02) and a higher concentration of propionate (P = 0.04) when compared to those consuming VM and adapted for 14 days. As the adaptation length decreased for animals consuming only VM, the rumen degradability of dry matter (P < 0.01), neutral detergent fiber (P < 0.01), and starch (P < 0.01) decreased; however, protozoa numbers of Entodinium and total protozoa increased. It is not recommended to shorten the adaptation length of these animals to either 6 or 9 days without negatively impacting nutrient disappearance and ruminal fermentation patterns.

Comparison of the effect of Saccharomyces cerevisiae-Megasphaera elsdenii and buffer on growth performance, digestibility, ruminal histomorphometry, and carcass characteristics of fattening lambs in high concentrate diet.

This study aimed to investigate the effect of rumen pH-adjusting additives in the high-concentrated diet on functional traits, nutrient digestion, some meat parameters, and histomorphometry, and rumen histopathology. Twenty-four Arabia male lambs with 3 to 4months old and initial body weight of 23.9 ± 3.15kg were used in a completely randomized design with three treatments and eight replicates. The study was 77days, including 14days of the adaptation period and 63days of the record taking and sampling period. The experimental treatments consisted of a control diet, control diet + sodium bicarbonate buffer, control diet + Megasphaera elsdenii, and Saccharomyces cerevisiae (bacterial-yeast). Rumen fluid was taken by stomach tube at 3h after morning feeding to measure pH. The lambs were weighed every 3weeks during the period, and the body weight changes, average daily gain, and total weight gain were measured, and the feed conversion ratio was calculated. At the end of the experiment, the lambs were slaughtered, and the longissimus dorsi muscle was prepared to determine the meat parameters. For histological studies, the abdominal rumen sac was sampled. There were no differences among treatments in dry matter intake (DMI), daily weight gain (ADG), and feed conversion ratio (P > 0.05). Propionate concentration was higher in the bacteria-yeast treatment than other treatments (P < 0.05). Protein digestibility was higher in control and bacteria-yeast treatments than buffer treatment (P < 0.05). The percentage of meat protein, carcass weight, and dressing percentage in bacterial-yeast treatment was higher than other treatments (P < 0.05). Rumen wall thickness in the buffer and bacterial-yeast receiving treatments was greater than the control treatment and was significant in the buffer treatment compared to the control treatment (P < 0.05). The thickness of rumen epithelial tissue in the buffer and bacterial-yeast recipient treatments was less than the control treatment (P < 0.05). Rumen papillae thickness was higher in the control treatment than other treatments (P < 0.05). Hydropic degeneration and parakeratosis were less in pH-regulating treatments than in control. The results showed that the use of Megasphaera elsdenii could be an effective way to modulate the ruminal fermentation conditions of lambs fed with high concentrate diets. In addition, to increaseing dressing percentage and meat protein, it can also reduce tissue damage and improve ruminal tissue structure.

Differential Diet and pH Effects on Ruminal Microbiota, Fermentation Pattern and Fatty Acid Hydrogenation in RUSITEC Continuous Cultures

The aim of this study was to distinguish effects due to diet composition from those triggered by ruminal pH on fermentation patterns and microbial profiles in a continuous culture system (RUSITEC). The study followed a 2 × 2 factorial design, with two diets varying in the proportions of forage and concentrate and two pH levels in the culture medium. RUSITEC fermenters were used to simulate rumen fermentation and feed digestibility, fermentation end-products, microbial protein synthesis, microbial community, and long-chain fatty acid profiles in the digesta were determined. Multivariate analyses were applied to summarize the overall results. High concentrate (34% cereal grain, 32% hay) diets were more digestible (p &lt; 0.05) than high forage (10% cereal grain, 78% hay) diets, resulting in a greater (p &lt; 0.05) formation of most fermentation end-products and microbial protein in the rumen. However, there were no significant (p &gt; 0.05) differences between diets in methane production. Ciliate protozoa, anaerobic fungi, some fibrolytic bacteria, hydrogenation of oleic acid, and relative proportion of conjugated linoleic acid were increased (p &lt; 0.05) with high forage diets. A decline in rumen pH from 6.8 to 6.4 decreased (p &lt; 0.05) feed digestibility, protein degradability, and the daily outputs of some fermentation end-products (gas, VFA, acetate, ammonia) but had no effect (p &gt; 0.05) on the synthesis of microbial protein, and on the output of methane, propionate, butyrate or lactate. Minor changes in microbial community profile or the fatty acid relative proportions were observed within this pH range. The overall multivariate analysis revealed a clear discrimination between high-concentrate and high-forage diets, with subtler and less-defined pH effects on ruminal fermentation and microbial communities.

Recent advances in research in the rumen bloat of ruminant animals fed high-concentrate diets.

Rumen bloat is the most common digestive disorder in fattening ruminants, which is responsible for around 2-3 % of deaths in the ruminants industry and is therefore considered to be a serious threat to ruminant farming. The root cause of rumen bloat caused by feeding high concentrate dies would be attributed to the production of a large amount of stable foam during the fattening period. The exact mechanism of rumen foam formation has yet to be investigated. Proteins, polysaccharides and carboxylates derived from feed, and synthesized by microbes during the rumen fermentation may act as foaming agents or stabilizers in the formation progress of rumen foam. Supplementation of condensed tannins and other additives can be an effective way to prevent feedlot bloat induced by feeding high concentrate diets.

Effects of Thymbra capitata essential oil on in vitro fermentation end-products and ruminal bacterial communities

An in vitro trial was carried out to investigate the effects of natural Thymbra capitata essential oil (NEO) and its main compounds [including carvacrol, p-cymene, γ-terpinene given alone or in a synthetic combination (SEO)] on ruminal fermentation and the bacterial community using batch cultures inoculated with ruminal digesta and incubating two different basal diets [high-forage (F) and high-concentrate (C) diet]. After 24 h of incubation, primary fermentation end-products [gas, methane, volatile fatty acids (VFAs) and ammonia] and rumen microbial diversity were determined. NEO reduced the total VFA concentration (P < 0.05) only in the C diet. In contrast, SEO and carvacrol decreased the total VFA concentration (P < 0.05) only in the F diet. Methane production was not affected (P > 0.05) by any of the experimental treatments or diets evaluated. Microbial diversity analysis showed only a moderate effect of carvacrol and SEO on 13 genera, including, mainly, Atopobium and Blautia (involved in subacute ruminal acidosis) or Candidatus Saccharimonas (related to laminitis). In conclusion, T. capitata EO has a limited potential to attain nutritional or environmental benefits, but further research should be carried out to clarify its effects on animal health and microbial food safety.

High concentrate diet induced inflammatory response and tight junction disruption in the mammary gland of dairy cows.

This study aimed to investigate the effect and mechanism of a high concentrate (HC) diet on the inflammatory response and cellular tight junctions (TJs) in the mammary gland of dairy cows. Twelve lactating Holstein dairy cows were randomly assigned into low concentrate (LC) and HC groups (n=6), which were fed with LC diet and HC diet respectively for 3 weeks. The HC diet lead to subacute ruminant acidosis with a rumen pH<5.6 more than 3h daily. The HC diet triggered an inflammatory response with increased levels of inflammatory cytokines in the lacteal vein, upregulated expression of inflammation-related genes, elevated activity of myeloperoxidase, and inflammatory cells infiltration in the mammary gland. Furthermore, the HC diet induced the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways with enhanced phosphorylation ratios of NF-κB P65, inhibitor of NF-κB (IκB), P38 and extracellular signal-regulated kinase 1/2 (ERK1/2) as well as decreased ratios of DNA methylation and chromatin compaction of genes coding for proinflammatory cytokines, which contributed to the upregulation of proinflammatory cytokine expression. The HC diet also destroyed the integrity of TJ with discontinuous and decreased expression levels of zonula occludens-1, Occludin, Claudin-4 and increased expression level of Claudin-1 in the mammary epithelial cells compared with LC group. Conclusively, the HC diet induced the activation of NF-κB and MAPK signaling pathways and epigenetic modifications, promoted the transcription of proinflammatory cytokines, and finally caused inflammatory response and TJ disruption in the mammary gland of dairy cows.

High-Dose Vitamin E Supplementation Can Alleviate the Negative Effect of Subacute Ruminal Acidosis in Dairy Cows.

The aim of this trial was to assess whether the supplementation of vitamin E (VE) in high-concentrate diets could improve the fermentation and blood metabolism in the rumen of dairy cows, thereby modulating the degree of the subacute ruminal acidosis (SARA) response and improving the performance. Seven Holstein cows (four fitted with ruminal cannulas) were fed three diets (total mixed rations) during three successive periods (each lasted for 18 d): (1) the control diet (CON); (2) a high-grain (HG) diet, which was the control diet supplied with a 15% finely ground wheat diet (FGW); and (3) a high-VE diet (HGE), which was the control diet provided with a 15% FGW and 12,000 IU of VE/head per day. The results indicated that VE was able to alleviate the reduction in the dry matter intake (DMI) and milk fat yield in cows caused by HG diets. The supplementation of VE significantly reduced the levels of lipopolysaccharide (LPS), histamine (HIS), and the total volatile fatty acid (TVFA) in the rumen. The supplementation of VE observably increased the antioxidant capacity of the milk and plasma. In addition, VE markedly reduced the plasma levels of endotoxin, HIS, and pro-inflammatory factors. The supplementation of VE significantly enriched the differential metabolites of the purine metabolism, cysteine, methionine metabolism, and ABC transporter synthesis pathway in the serum. The supplementation of VE also significantly increased the relative abundance of Succiniclasticum and decreased the relative abundance of Treponema, thus reducing the production of TVFA in the rumen. In conclusion, considering that the cows in this trial had high ketone levels (BHBA > 2.3 mmol/L), we found that VE could improve the rumen fermentation and blood metabolism by modulating the relative abundance of rumen microorganisms, thereby mitigating a range of adverse effects caused by SARA.

Effects of low-fat dried distillers grains on nutrient intake and digestibility in high-concentrate diets

This study aimed to evaluate the effect of including levels of low-fat dried distillers grains without soluble (DDG) in high-concentrate diets on intake and digestibility. Four rumen-cannulated Nellore cattle received four dietary treatments in a 4×4 Latin square experimental design. Treatments included diets without DDG (D0) and varying inclusion levels of DDG at 150 g/kg (D150), 300 g/kg (D300), and 450 g/kg (D450). Four periods of total feces and urine collection were performed to estimate nutrient intake and digestibility and estimate nitrogen balance. Collections of omasum digesta were used to estimate ruminal degradability. The ruminal emptying technique was performed to estimate the ruminal rates of ingestion, passage, and digestion (kd). The inclusion of DDG reduced the intake of total digestible nutrients (TDN) (P < 0.01), dry matter (DM) (P = 0.02), organic matter (OM) (P = 0.02), non-fiber carbohydrates (NFC) (P < 0.01) and ether extract (EE) (P = 0.06). The intake of neutral detergent fiber (NDF) increased linearly (P < 0.01), whereas CP had a quadratic pattern (P = 0.02). The total digestibility in kg/d of DM (P < 0.01), OM (P < 0.01), NFC (P < 0.01) and EE (P = 0.02) decreased linearly. The total digestibility in kg/d of the NDF increased linearly (P < 0.01) and the CP had a quadratic pattern (P = 0.01). The kd of DM (P = 0.01), OM (P < 0.01) decreased linearly and NDF increased linearly (P < 0.01). The amount of N retained did not change (P = 0.72), but the intake of metabolizable protein increased (P = 0.03). Therefore, the inclusion of low-fat DDG in finishing diets reduces TDN intake and reduces the digestibility of almost all nutrients.

Essential oil from Arnica montana on feedlot performance, ingestive behavior, carcass characteristics, rumen morphometrics characteristics and meat fatty acids profile of lambs

This study aimed to evaluate the effects of Essential oil (EO) from Arnica montana as a feed additive on feedlot performance, ingestive behavior, carcass characteristics, rumen morphometrics characteristics and meat fatty acids profile of lambs. Forty Dorper × Santa Inês male lambs with 30.3 ± 5.76 kg (mean ± standard deviation) of initial body weight and 92 ± 9 days (mean ± standard deviation) of age were used. The experimental design was in a randomized complete block (5 treatments and 8 blocks). Lambs were fed a basal diet (160 ± 13 g/kg DM of CP; mean ± standard deviation) containing 90 % concentrate and 10 % forage (Coastcross hay). The experimental diets were: A0 - negative control (basal diet without additive); A450 - addition of 450 mg/kg DM of EO from Arnica montana; A900 - addition of 900 mg/kg DM of EO from Arnica montana; A1350 - addition of 1350 mg/kg DM of EO from Arnica montana; M25 - positive control (basal diet containing 25 mg/kg DM of sodium monensin). Increasing EO from Arnica montana content conferred a quadratic effect on dry matter intake (DMI) (P = 0.02), with higher DM in A450. The DMI was higher (P < 0.01) in diets with EO from Arnica montana compared to M25. The average daily gain (ADG), body weight at slaughter (BWS), hot and cold carcass weight (HCW and CCW) increased linearly with increasing EO from Arnica montana (P < 0.05). The lambs had higher ADG, BWS, HCW and CCW with EO from Arnica montana than M25 (P < 0.05). The oocyst/g feces decreased linearly (P < 0.0001) with increasing EO from Arnica montana in the diet. However, the M25 was more efficient in reducing the oocyst than the other treatments (P < 0.05). The number of meals and time spent feeding increased linearly (P < 0.05) with the increase of EO from Arnica montana. There was a quadratic effect (P < 0.05) on feeding rate (min/g DM), with the lowest rate in A450. Time spent ruminating (min/day) was affected quadratically (P = 0.01) by increasing EO from Arnica montana, this activity was higher in A900. Compared to M25, time spent ruminating and total chewing time were longer (P < 0.05) and the feeding rate and chewing rate (min/g of NDF) were lower (P < 0.05) in diets with EO from Arnica montana. The higher inclusion of EO from Arnica montana decreased linearly the C17:0; C18:0; C18:1 trans-11, C22:6 n3 and the sum of saturated fatty acids (ΣSFA), and linearly increased the C18: 2 cis-9, cis-12; C18:3 cis-9, cis-12, cis-15, the sum of polyunsaturated (ΣPUFA) and the sum of n6 (P < 0.05). Diets with EO from Arnica montana decreased the C16:0, C17:0, C18:0 and increased the C18:2 cis-9, cis-12, ΣSFA, Σn6 and the n6/n3 ratio (P < 0.05) compared to M25. Sodium monensin at a dose of 25 mg/kg DM can be replaced by EO from Arnica montana in high-concentrate diets to promote lamb performance, carcass characteristics and fatty acid profile in the meat. The use of 1350 mg/kg DM of EO from Arnica montana was the best dose in high-concentrate diets in feedlot lambs, due to positive effect on performance, carcass characteristics, and the fatty acid profile of the meat.

Disodium Fumarate Alleviates Endoplasmic Reticulum Stress, Mitochondrial Damage, and Oxidative Stress Induced by the High-Concentrate Diet in the Mammary Gland Tissue of Hu Sheep

The long-term feeding of the high-concentrate diet (HC) reduced rumen pH and induced subacute rumen acidosis (SARA), leading to mammary gland tissue damage among ruminants. Disodium fumarate enhanced rumen bufferation and alleviated a decrease in rumen pH induced by the HC diet. Therefore, the purpose of this study was to investigate whether disodium fumarate could alleviate endoplasmic reticulum (ER) stress, mitochondrial damage, and oxidative stress induced by the high-concentrate diet in the mammary gland tissue of Hu sheep. In this study, 18 Hu sheep in mid-lactation were randomly divided into three groups: one fed with a low-concentrate diet (LC) diet, one fed with a HC diet, and one fed with a HC diet with disodium fumarate (AHC). Each sheep was given an additional 10 g of disodium fumarate/day. The experiment lasted for eight weeks. After the experiment, rumen fluid, blood, and mammary gland tissue were collected. The results show that, compared with the LC diet, the HC diet could reduce rumen pH, and the pH below 5.6 was more than 3 h, and the LPS content of blood and rumen fluid in HC the diet was significantly higher than in the LC diet. This indicates that the HC diet induced SARA in Hu sheep. However, the supplementation of disodium fumarate in the HC diet increased the rumen pH and decreased the content of LPS in blood and rumen fluid. Compared with the LC diet, the HC diet increased Ca2+ content in mammary gland tissue. However, the AHC diet decreased Ca2+ content. The HC diet induced ER stress in mammary gland tissue by increasing the mRNA and protein expressions of GRP78, CHOP, PERK, ATF6, and IRE1α. The HC diet also activated the IP3R-VDAC1-MCU channel and lead to mitochondrial damage by inhibiting mitochondrial fusion and promoting mitochondrial division, while disodium fumarate could alleviate these changes. In addition, disodium fumarate alleviated oxidative stress induced by the HC diet by activating Nrf2 signaling and reducing ROS production in mammary gland tissue. In conclusion, the supplementation of disodium fumarate at a daily dose of 10 g/sheep enhanced rumen bufferation by maintaining the ruminal pH above 6 and reduced LPS concentration in ruminal fluid and blood. This reaction avoided the negative effect observed by non-supplemented sheep that were fed with a high-concentrate diet involving endoplasmic reticulum stress, oxidative stress, and mitochondrial damage in the mammary gland tissue of Hu sheep.

Subacute ruminal acidosis downregulates FOXA2, changes oxidative status, and induces autophagy in the livers of dairy cows fed a high-concentrate diet

The purpose of this experiment was to investigate high-concentrate feeding-induced changed status of oxidative and autophagy in the livers of dairy cows. Hepatocyte nuclear factor 3β (FOXA2) was reported in cases of liver fibrosis, glucolipid metabolism, and hepatocyte differentiation, but not in cases liver damage in cows fed a high-concentrate diet. Therefore, we also aimed to explore the potential role of FOXA2 in SARA-induced liver damage. We divided 12 mid-lactating Holstein cows into 2 groups and fed them a high-concentrate (HC group, forage:concentrate = 4:6) and a low-concentrate (forage:concentrate = 6:4) diet. After a 2-wk adaptation period and a 3-wk experimental period, peripheral blood was collected for determination of antioxidant enzyme activity, and liver tissue was collected to examine genes and proteins. On d 20 and 21 of the experiment, rumen fluid was collected, and the pH was measured. A significant difference in rumen fluid pH was found between the 2 groups (low-concentrate: 6.10 ± 0.07 vs. HC: 5.59 ± 0.09). The rumen fluid pH in the HC group was less than 5.6 at 2 time points, indicating that SARA was successfully induced. Lipopolysaccharide (0.24 ± 0.10 vs. 0.42 ± 0.12) and malondialdehyde (1.46 ± 0.25 vs. 2.94 ± 0.65) increased, whereas superoxide dismutase (14.06 ± 0.63 vs. 11.71 ± 0.64), reduced glutathione (14.48 ± 2.25 vs. 6.82 ± 0.67), and the total antioxidant capacity (0.43 ± 0.03 vs. 0.30 ± 0.03) decreased in the peripheral blood of the HC group. Moreover, in liver tissue from the HC group, catalase (0.71 ± 0.03 vs. 0.49 ± 0.03) and superoxide dismutase (27.46 ± 1.90 vs. 20.32 ± 1.54) were decreased, whereas malondialdehyde (0.21 ± 0.03 vs. 0.28 ± 0.03) was elevated. Meanwhile, we observed lower gene expression of CAT (1.00 ± 0.15 vs. 0.64 ± 0.17), NAD(P)H quinone dehydrogenase 1 (NQO1; 1.00 ± 0.09 vs. 0.47 ± 0.14), glutathione peroxidase 1 (GPX1; 1.03 ± 0.27 vs. 0.55 ± 0.09), SOD1 (1.01 ± 0.17 vs. 0.76 ± 0.17), and SOD3 (1.02 ± 0.21 vs. 0.55 ± 0.16) in the liver tissue of the HC group. Furthermore, western blot analysis showed that high-concentrate feeding led to decreased sirtuin-1 (SIRT1) (1.00 ± 0.10 vs. 0.62 ± 0.15) and FOXA2 (1.02 ± 0.19 vs. 0.68 ± 0.18), elevated autophagy-related protein microtubule associated protein 1 light chain 3 II (MAP1LC3-II; 1.00 ± 0.32 vs. 1.98 ± 0.83) and autophagy related 5 (ATG5; 1.00 ± 0.30 vs. 1.80 ± 0.27), and suppressed antioxidant signaling pathway-related protein nuclear factor erythroid 2-like 2 (NFE2L2; 1.00 ± 0.18 vs. 0.61 ± 0.30) and heme oxygenase 1 (HMOX1; 1.00 ± 0.48 vs. 0.38 ± 0.25) in liver tissue. Overall, these data indicated that SARA elevated systematic oxidative status and enhanced autophagy in the liver, and suppressed SIRT1 and FOXA2 may mediate enhanced oxidative damage and autophagy in the livers of dairy cows fed a high-concentrate diet.

Effect of physically effective neutral detergent fiber and undigested neutral detergent fiber on eating behavior, ruminal fermentation and motility, barrier function, blood metabolites, and total tract digestibility in finishing cattle.

This study evaluated the effects of physically effective neutral detergent fiber (peNDF) and undigested neutral detergent fiber (uNDF) on eating behavior, ruminal fermentation and motility, barrier function, blood metabolites, and total tract nutrient digestibility for finishing cattle. Six Simmental heifers (668 ± 28.4 kg BW) were used in a replicated 3 × 3 Latin square (21 d periods) balanced for carry-over effects. Treatments included a control (CON; Table 1) with no forage peNDF and minimal uNDF (peNDF: 0.0%, and uNDF: 4.88 ± 0.01; 95.15% barley grain, 4.51% vitamin and mineral supplement, and 0.34% urea on a DM basis). Pelleted wheat straw (PELL) was included at 10% of dietary DM by replacing barley grain to provide added uNDF but no forage peNDF (peNDF: 0.00%, and uNDF: 6.78 ± 0.02%). Finally, chopped wheat straw (STR) was included as a replacement for pelleted wheat straw to provide forage peNDF and uNDF (peNDF: 1.74 ± 0.06%, and uNDF: 6.86 ± 0.03%). Dry matter intake was not affected (P = 0.93) by treatments. Cattle fed CON spent less time ruminating (P = 0.010) and had less meals/d (P = 0.035) when compared with cattle fed STR, with those fed PELL being intermediate but not different from other treatments. Cattle fed CON had lesser ruminal pH (P = 0.020), and a greater duration that pH was < 5.5 (P = 0.020) as compared to cattle fed STR, with those fed PELL being intermediate but not different. Cattle fed CON and PELL had greater total short-chain fatty acid concentration (P = 0.003) and molar proportion of propionate (P < 0.001) when compared with cattle fed STR. Cattle fed STR had greater (P = 0.010) total ruminal pool size when compared with cattle fed CON and PELL. Cattle fed CON had greater (P = 0.043) duration between ruminal contractions when compared with cattle fed STR, with those fed PELL being intermediate. Cattle fed CON had greater serum amyloid A (P = 0.003) and haptoglobin (P < 0.001) concentration when compared with the other treatments. Cattle fed CON had greater dry matter (P < 0.001) digestibility when compared with the other treatments. In conclusion, inclusion of PELL and STR impacted eating behavior, but only STR affected ruminal fermentation, ruminal motility, systemic inflammation, and total tract nutrient digestibility in finishing cattle. These results are interpreted to suggest that the combination of peNDF and uNDF may be better than uNDF alone to adequately capture biological effects of NDF in high-concentrate diets.

Feeding 3-nitrooxypropanol reduces methane emissions by feedlot cattle on tropical conditions.

Our objective was to evaluate the effects of feeding 3-nitrooxypropanol (3-NOP; Bovaer®, DSM Nutritional Products) at two levels on methane emissions, nitrogen balance and performance by feedlot cattle. In exp. 1, a total of 138 Nellore bulls (iBW, 360 ± 37.3kg) were housed in pens (27 pens with either 4 or 5 bulls per pen) and fed a high-concentrate diet for 96 days, containing 1) no addition of 3-NOP (control), 2) inclusion of 3-NOP at 100mg/kg DM, and 3) inclusion of 3-NOP at 150mg/kg DM. No adverse effects of 3-NOP were observed on DM intake, animal performance and gain:feed (P > 0.05). In addition, there was no effect (P > 0.05) of 3-NOP on carcass characteristics (subcutaneous fat thickness and rib eye area). In exp. 2, 24 bulls (iBW, 366 ± 39.6kg) housed in 12 pens (two bulls/pen) from Exp.1 were used for CH4 measurements and nitrogen balance. Irrespective of the level, 3-NOP consistently decreased (P < 0.001) animals' CH4 emissions (g/d; ~ 49.3%), CH4 yield (CH4/DM intake; ~40.7%) and CH4 intensity (CH4/ADG; ~38.6%). Moreover, 3-NOP significantly reduced the gross energy intake lost as CH4 by 42.5% (P < 0.001). The N retention: N intake ratio was not affected by 3-NOP (P = 0.19). We conclude that feeding 3-NOP is an effective strategy to reduce methane emissions, with no impairment on feedlot cattle performance.

Effects of medium-chain fatty acids (MCFAs) on in vitro rumen fermentation, methane production, and nutrient digestibility under low- and high-concentrate diets.

This experiment was conducted to investigate the effects of different dosages and types of medium-chain fatty acids (MCFAs) on rumen fermentation in vitro under low- and high-concentrate diets. For this purpose, two in vitro experiments (Exp.) were conducted. In Exp. 1, the concentrate-roughage ratio of the fermentation substrate [total mixed rations (TMR), dry matter (DM) basis] was 30:70 (low-concentrate diet), while in Exp. 2, it was 70:30 (high-concentrate diet). Three types of MCFAs with octanoic acid (C8 ), capric acid (C10 ), and lauric acid (C12 ) were added accounting for 1.5%, 6%, 9%, and 15% of the in vitro fermentation substrate weight (200 mg or 1g, DM basis) based on control group, respectively. The results showed that the addition of MCFAs all could significantly reduce methane (CH4 ) production and the number of rumen protozoa, methanogens, and methanobrevibacter under the two diets with the dosages increased (p < 0.05). In addition, MCFAs had a certain degree of improvement on rumen fermentation and influenced in vitro digestibility under low- and high-concentrate diets, and their effects were related to the dosages and types of MCFAs. This study provided a theoretical basis for the selection of types and dosages of MCFAs in ruminants production.