Carbohydrates are the primary energy source for lactating dairy cows, and dairy diets are usually formulated for certain concentrations of forage neutral detergent fiber (NDF) and starch due to their ...direct effects on dry matter intake and milk production. Forage NDF exerts greater filling effects in the rumen than other dietary components and can limit maximum voluntary feed intake of lactating dairy cows. Since an analytical method for NDF was developed more than a half century ago, it has been used widely to characterize forages and diets for dairy cows. However, because NDF is a chemical measurement varying in its digestibility, in vitro digestibility measurements were developed as a biological approach to assess forage quality. Research efforts over the last several decades led to the development of forage cultivars or hybrids with enhanced in vitro NDF digestibility, such as brown midrib, and management practices considering differences in NDF digestibility of forages. In addition, in vitro NDF digestibility and undigested NDF are commonly measured in commercial labs, and estimated rates of digestion are used in dynamic models in an effort to improve the accuracy and precision of diet formulation. Starch digestion in the rumen also varies among starch sources, being affected by grain type, extent of processing, and conservation method. The site and rate of starch digestion affect dry matter intake and nutrient partitioning in dairy cows by modifying temporal supply of fuel. In addition, dietary starch content and its fermentability can affect digestion rates of starch itself and NDF in the rumen. Previous research has increased our understanding of dietary carbohydrates, but its application for diet formulations requires integrated approaches accounting for factors affecting the filling effects of forage NDF, starch digestion, and temporal fuel supply.
The objectives of the current study were to evaluate the variation in severity of subacute ruminal acidosis (SARA) among lactating dairy cows fed a high-grain diet and to determine factors ...characterizing animals that are tolerant to high-grain diets. Sixteen ruminally cannulated late-lactating dairy cows (days in milk=282±33.8; body weight=601±75.9kg) were fed a high-grain diet consisting of 35% forage and 65% concentrate mix. After 17 d of diet adaptation, chewing activities were monitored for a 24-h period and ruminal pH was measured every 30s for 72h. Acidosis index, defined as the severity of SARA (area of pH <5.8) divided by dry matter intake (DMI), was determined for individual animals to assess the severity of SARA normalized for a feed intake level. Although all cows were fed the same diet, minimum pH values ranged from 5.16 to 6.04, and the acidosis index ranged from 0.0 to 10.9 pH·min/kg of DMI. Six cows with the lowest acidosis index (0.04±0.61 pH·min/kg) and 4 with the highest acidosis index (7.67±0.75 pH·min/kg) were classified as animals that were tolerant and susceptible to the high-grain diet, respectively. Total volatile fatty acid concentration and volatile fatty acid profile were not different between the groups. Susceptible animals sorted against long particles, whereas tolerant animals did not (sorting index=87.6 vs. 97.9, respectively). However, the tolerant cows had shorter total chewing time (35.8 vs. 45.1min/kg of DMI). In addition, although DMI, milk yield, and milk component yields did not differ between the groups, milk urea nitrogen concentration was higher for tolerant cows compared with susceptible cows (12.8 vs. 8.6mg/dL), which is possibly attributed to less organic matter fermentation in the rumen of tolerant cows. These results suggest that a substantial variation exists in the severity of SARA among lactating dairy cows fed the same high-grain diet, and that cows tolerant to the high-grain diet might be characterized by less sorting behavior but less chewing time, and higher milk urea nitrogen concentration.
The objective of this study was to examine whether lactating dairy cows with a greater or lower risk of subacute ruminal acidosis (SARA) have differences in volatile fatty acid (VFA) absorption rate, ...expression of genes involved in VFA metabolism and intracellular pH regulation in rumen epithelial cells, and in situ carbohydrate digestibility in the rumen. We fed 14 ruminally cannulated mid-lactating dairy cows (119±47.2d in milk; body weight 640±47.9kg) a high-grain diet consisting of 30% forage ad libitum, with an 18-d diet adaptation and a 7-d sample and data collection period. Eight cows with the lowest acidosis index area below pH 5.8 normalized for dry matter intake (DMI); 0.10±0.16 pH × min/kg of DMI and 5 with the highest acidosis index (3.72±0.19 pH × min/kg of DMI) were classified as animals with lower risk (LS) and higher risk (HS) of SARA, respectively. Minimum (5.75 vs. 5.33) and mean rumen pH (6.33 vs. 5.98) were higher for LS than for HS cows. In addition, the duration and area of rumen pH below 5.8 was lower in LS cows (24.9 vs. 481min/d; 2.94 vs. 102 pH × min/d). Although DMI, milk yield, and milk component yields did not differ, milk fat concentration tended to be higher for LS cows than for HS cows (3.36 vs. 2.93%). However, we observed no difference in VFA absorption rate between LS and HS cows. In situ starch and neutral detergent fiber digestibility were not different between LS and HS cows, but the relative mRNA abundance of lanosterol synthase (LSS) was higher for LS cows than for HS cows. In addition, the mRNA abundance of hydroxy-3-methylglutaryl-CoA synthase 1 (HMGCS1) tended to be higher for LS cows than for HS cows. These results suggested that VFA absorption rate might not explain the difference in rumen pH between LS and HS cows in the current study, even though expression of some genes related to VFA metabolism in rumen epithelium may be associated with variation in the risk of SARA among lactating cows. This variation in the risk of SARA may not be attributed to differences in the capacity of rumen microbes to ferment carbohydrates, because in situ carbohydrate digestibility in the rumen was not different between cows with higher and lower risk of SARA.
Feed and energy intake of ruminant animals can change dramatically in response to changes in diet composition or metabolic state, and such changes are poorly predicted by traditional models of feed ...intake regulation. Recent work suggests that temporal patterns of fuel absorption, mobilization, and metabolism affect feed intake in ruminants by altering meal size and frequency. Research with nonruminants suggests that meals can be terminated by signals carried from the liver to the brain via afferents in the vagus nerve and that these signals are affected by hepatic oxidation of fuels and generation of ATP. We find these results consistent with the effects of diet on feed intake of ruminants. Of fuels metabolized by the ruminant liver, propionate is likely a primary satiety signal because its flux to the liver increases greatly during meals. Propionate is utilized for gluconeogenesis or oxidized in the liver and stimulates oxidation of acetyl CoA. Although propionate is extensively metabolized by the ruminant liver, there is little net metabolism of acetate or glucose, which may explain why these fuels do not consistently induce hypophagia in ruminants. Lactate is metabolized in the liver but has less effect on satiety, probably because of greater latency for reaching the liver within meals and because of less hepatic extraction compared with propionate. Hypophagic effects of fatty acid oxidation in the liver are likely from delaying hunger rather than promoting satiety because β-oxidation is inhibited during meals by propionate. A shortage of glucose precursors and increased fatty acid oxidation in the liver for early lactation cows lead to a lack of tricarboxylic acid (TCA) cycle intermediates, resulting in a buildup of the intracellular acetyl-CoA pool and export of ketone bodies. In this situation, hypophagic effects of propionate are likely enhanced because propionate entry into the liver provides TCA cycle intermediates that allow oxidation of acetyl-CoA. Oxidizing the pool of acetyl-CoA rather than exporting it increases ATP production and likely causes satiety despite the use of propionate for glucose synthesis. A better understanding of metabolic regulation of feed intake will allow diets to be formulated to increase the health and productivity of ruminants.
Microglia are essential for CNS homeostasis and innate neuroimmune function, and play important roles in neurodegeneration and brain aging. Here we present gene expression profiles of purified ...microglia isolated at autopsy from the parietal cortex of 39 human subjects with intact cognition. Overall, genes expressed by human microglia were similar to those in mouse, including established microglial genes CX3CR1, P2RY12 and ITGAM (CD11B). However, a number of immune genes, not identified as part of the mouse microglial signature, were abundantly expressed in human microglia, including TLR, Fcγ and SIGLEC receptors, as well as TAL1 and IFI16, regulators of proliferation and cell cycle. Age-associated changes in human microglia were enriched for genes involved in cell adhesion, axonal guidance, cell surface receptor expression and actin (dis)assembly. Limited overlap was observed in microglial genes regulated during aging between mice and humans, indicating that human and mouse microglia age differently.
The objective of this experiment was to determine the effect of pellet type and feeding amount on feeding behavior, dry matter intake, rumen fermentation, and milk production of lactating dairy cows. ...An experimental diet was formulated to provide an adequate amount of nutrients to a 650-kg cow producing 40 kg of milk per day, with a portion of the diet removed as a high-fiber (33.2% neutral detergent fiber; F) or high-starch (56.8% starch; S) pellet. Pellets were fed at a low (1 kg; L) or high (3 kg; H) amount twice per day alongside a partial mixed ration (PMR). Four complementary PMR were formulated for each pellet treatment such that the overall diet (pellet + PMR) offered to the cows was the same among all treatments. Eight ruminally cannulated cows were used in a 4 × 4 Latin square design with 14-d periods. Cows were fed PMR once daily at 1200 h, and pellet twice daily at 0600 and 1800 h. Data and samples were collected on d 11 to 14 of each period. By design there was a difference in pellet intake between the H and L treatments (5.31 vs. 1.81 kg/d), and PMR intake was reduced when H pellet was fed (22.9 vs. 25.3 kg/d); however, feeding H tended to increase total dry matter intake. Feed disappearance, which was measured as the amount of PMR consumed every 3 h following PMR delivery, was affected by the nutrient composition of the PMR as cows fed S (with high-fiber PMR) consumed 28.6% of their PMR intake within 3 h of delivery, whereas cows fed F (with high-starch PMR) consumed 33.5%. Duration that pH was below 5.8 tended to be lower when cows were fed the S pellet (270 vs. 125 min/d) compared with F. In addition, feeding the S pellet (with high-fiber PMR) decreased plasma concentrations of glucose (66.0 vs. 70.0 mg/dL) and insulin (1.90 vs. 2.25 ng/mL) compared with F. These results suggest that the composition of the PMR dictates rumen fermentation to a greater extent than composition of pellets. The S pellet was fed alongside a high-fiber PMR, which was more filling in the rumen, less fermentable, and contained more neutral detergent fiber. Although no difference was observed in milk production among treatments, the fact that feed intake pattern and rumen fermentation are better explained by nutrient composition of the PMR should be considered when formulating diets for lactating cows fed pellet and PMR, such as those milked with automated milking systems.
The objective of the present study was to evaluate the effects of offering free-choice hay to cows during the first 5 d immediately after calving on feed intake, milk yield, plasma metabolites, serum ...inflammatory markers, rumination, gut permeability, and colon gene expression. It was hypothesized that cows offered free-choice hay would have lower gut permeability, lower inflammation, and higher milk production, compared with cows not offered hay. Thirty-two multiparous cows were fed a closeup total mixed ration (TMR; 21.5% starch, 32.1% forage neutral detergent fiber NDF on a dry matter basis) until calving. In the postpartum period, all cows were fed a fresh cow TMR (26.8% starch and 23.4% forage NDF) from calving until 21 DIM, and were assigned randomly to receive 1 of 2 treatments as follows: (1) free-choice timothy hay (61.6% NDF; 9.6% crude protein), offered outside of the TMR in a separate manger, for the first 5 d postpartum (FCH; n = 20), or 2) no free-choice hay (NH; n = 12). The FCH cows tended to have lower serum haptoglobin concentration on d 3, compared with NH (0.95 vs. 1.52 mg/mL). Within the FCH group, cows with greater hay intake had a smaller increase in serum amyloid A from d 1 to 3 after calving (r = 0.37), and tended to have a smaller increase in serum haptoglobin concentration (r = 0.36). Cows in the FCH group had a lower ratio of starch intake (kg) to forage NDF intake (kg) on d 1 and 2, compared with NH (0.91 vs. 1.14 ± 0.03), and cows that had a lower starch:forage NDF ratio tended to have a smaller increase in serum haptoglobin concentration from d 1 to 3 after calving (r = 0.32). Cows in the FCH group had lower TMR dry matter intake (DMI; 15.0 vs. 17.1 ± 0.93 kg/d) and lower total DMI (TMR + hay DMI; 15.9 vs. 17.1 ± 0.87 kg/d), from d 1 to 5 when free-choice hay was offered, compared with NH. However, the hay treatment did not affect plasma energy metabolite concentration, gut permeability, colon gene expression, milk yield, rumination time, or change in body weight or body condition score. Overall, these findings suggest that offering free-choice hay for the first 5 d after calving may reduce serum inflammatory marker concentration, but milk yield may not increase, due to lower intake.
The objective of this study was to investigate effects of increasing dietary nonfiber carbohydrate (NFC) with starch, sucrose, or lactose on rumen fermentation, volatile fatty acid absorption, and ...milk production of lactating dairy cows. Twenty-eight multiparous, lactating Holstein cows (141±50 d in milk; 614±53kg of body weight) including 8 ruminally cannulated cows were used in this study. Cows were assigned to 4 dietary treatments in a 4×4 Latin square design with 21-d periods. The treatments were control 27% starch and 4% sugar on a dry matter (DM) basis, a high-NFC diet by increasing dietary starch content (STA; 32% starch and 4% sugar on a DM basis), and 2 more high-NFC diets by increasing dietary sugar content (27% starch and 9% sugar on a DM basis) in which sucrose (SUC) or lactose (LAC) was supplemented. Dry matter intake was greater for cows fed high-NFC diets compared with control diet (27.1 vs. 26.3kg/d), but rumen pH and milk production did not differ between cows fed control and high-NFC diets. However, cows fed high-disaccharide diets had lower mean rumen pH than those fed STA diet (6.19 vs. 6.32). Although molar proportion of butyrate was greater for high-disaccharide treatments than STA treatment (15.2 vs. 13.7 mol/100 mol), absorption rate of volatile fatty acid in the rumen was not affected by treatment. In addition, cows fed high-disaccharide diets had higher energy-corrected milk yield than cows fed STA diet (39.6 vs. 38.0kg/d). Dry matter intake did not differ between cows fed 2high-disaccharide diets. Although cows fed the SUC diet had lower molar proportion of butyrate in the rumen compared with those fed the LAC diet (14.4 vs. 15.9 mol/100 mol), the SUC diet did not decrease rumen pH. In addition, cows fed the SUC diet had lower nutrient digestibility of organic matter than did those fed the LAC diet (59.7 vs. 64.4%), but milk component yields did not differ between the 2 high-disaccharide diet treatments. The results of the present study suggested that partially replacing dietary starch with disaccharides increased DM intake and energy-corrected milk, although rumen pH decreased for high-disaccharide diets, and that the rumen pH responses cannot be attributed to difference in absorption rate of volatile fatty acids in the rumen. In addition, type of sugars affected nutrient digestibility and rumen fermentation, but the effects were not large enough to affect rumen pH and milk production.
Dairy cattle experience inflammation during the calving transition period, and butyrate and nonsteroidal anti-inflammatory drugs (NSAID) are expected to reduce the inflammation. Our objective was to ...evaluate the effects of dietary butyrate supplementation and oral NSAID administration on feed intake, serum inflammatory markers, plasma metabolites, and milk production of dairy cows during the calving transition period. Eighty-three Holstein cows were used in the experiment with a 2 × 2 factorial arrangement of treatments. The cows were blocked by parity and calving date, and randomly assigned to a dietary butyrate or control supplement, and NSAID or a placebo oral administration. Experimental diets were iso-energetic containing calcium butyrate at 1.42% of diet dry matter (DM) or the control supplement (1.04% commercial fat supplement and 0.38% calcium carbonate of diet DM). The close-up diets contained 13.3% starch and 42.4% neutral detergent fiber on a DM basis, and were fed from 28 d before expected calving date until calving. The postpartum diets contained 22.1% starch and 34.1% neutral detergent fiber on a DM basis and were fed from calving to 24 d after calving. Oral NSAID (1 mg of meloxicam/kg of body weight) or placebo (food dye) was administered 12 to 24 h after calving. Dietary butyrate supplementation and oral NSAID administration did not affect milk yield or postpartum serum concentrations of amyloid A and haptoglobin. However, butyrate-fed cows increased plasma fatty acid concentration on d −4 relative to calving (501 vs. 340 μEq/L) and tended to increase serum haptoglobin concentration (0.23 vs. 0.10 mg/mL). There was a supplement by drug interaction effect on plasma glucose concentration on d 4; in cows administered the placebo drug, butyrate supplementation decreased plasma glucose concentration compared with control-fed cows (62.8 vs. 70.1 mg/dL). Butyrate-fed cows tended to have lower milk crude protein yield compared with cows fed the control diet (1.21 vs. 1.27 kg/d). Dietary butyrate supplementation and oral NSAID administration did not have overall positive effects on production performance of dairy cows during the calving transition period.
Abstract
Canine obesity negatively influences health and well-being, but can be managed by altering diet composition and caloric intake. Restricted feeding, dietary intervention, and consequent ...weight loss may be used to improve health and modify gastrointestinal microbiota. In this study, we aimed to determine the effects of restricted feeding of specially formulated foods on weight loss, body composition, voluntary physical activity, serum hormones and oxidative stress markers, and fecal metabolites and microbiota populations of obese dogs. Twenty-four obese dogs body weight (BW) = 15.2 ± 1.7 kg; body condition score (BCS) = 8.7 ± 0.4; muscle condition score (MCS) = 3.5 ± 0.3; age = 7.2 ± 1.6 yr were used in a 24-wk study. A control (OR) food was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline, dogs were allotted to one of two diets: OR or test (FT), and then fed to lose 1.5% BW/wk. Food intake, BW, BCS, and MCS were measured, blood and fecal samples were collected, DEXA scans were performed, and voluntary physical activity was measured over time. Microbiota data were evaluated using QIIME2 and change from baseline data from other measures were evaluated using the Mixed Models procedure of SAS, with P < 0.05 being significant. Restricted feeding led to reduced BW, BCS, fat mass, and blood cholesterol, triglyceride, glucose, and leptin concentrations, and increased MCS and lean body mass percentage. Blood cholesterol reduction was greater in dogs fed FT vs. OR. Fecal metabolites and bacterial alpha-diversity were affected by diet and weight loss. Dogs fed FT had greater reductions in fecal short-chain fatty acid, branched-chain fatty acid, and ammonia concentrations than those fed OR. Dogs fed OR had a higher alpha-diversity than those fed FT. Weight loss increased alpha-diversity (weeks 16, 20, and 24 > weeks 0 and 4). Beta-diversity showed separation between dietary groups and between week 0 and all other time points after week 8. Weight loss increased fecal Allobaculum and Ruminococcus torques. Weight loss also increased fecal Bifidobacterium, Faecalibaculum, and Parasutterella, but were greater in dogs fed OR. Weight loss decreased fecal Collinsella, Turicibacter, Blautia, Ruminococcus gnavus, Faecalibacterium, and Peptoclostridium, but were greater in dogs fed OR. In summary, restricted feeding promoted safe weight and fat loss, reduced blood lipid and leptin concentrations, and altered fecal microbiota of obese dogs.
In this study, we aimed to determine the effects of restricted feeding of specially formulated foods on weight loss, body composition, voluntary physical activity, serum hormones and oxidative stress markers, and fecal metabolites and microbiota populations of obese dogs. Restricted feeding, with high-protein, low-starch kibble diets, was shown to promote safe weight and fat loss, reduce blood lipid and leptin concentrations, and alter fecal microbiota.
Lay Summary
In this study, we aimed to determine the effects of restricted feeding of specially formulated foods on weight loss, body composition, voluntary physical activity, serum hormones and oxidative stress markers, and fecal metabolites and microbiota populations of obese dogs. A control (OR) food was fed during a 4-wk baseline to identify intake needed to maintain the body weight (BW). After baseline, dogs were allotted to one of two diets: OR or test (FT) and then fed to lose 1.5% BW per week for 24 wk. Restricted feeding and weight loss led to reduced BW, body condition score, fat mass, and blood cholesterol, triglyceride, glucose and leptin concentrations and increased muscle condition score and lean body mass percentage. The reduction in blood cholesterol was greater in dogs fed FT vs. OR. Fecal metabolites and bacterial alpha-diversity were affected by diet and weight loss, with dogs fed with OR having a higher alpha-diversity than those fed with FT. Restricted feeding and weight loss increased alpha-diversity, affected beta-diversity, and impacted the relative abundances of nearly 20 bacterial genera. In summary, restricted feeding with high-protein, low-starch kibble diets promoted safe weight and fat loss, reduced blood lipid and leptin concentrations, and altered fecal microbiota of obese dogs.
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