Fed HF Diets Research Articles

Proteome changes in an aquatic invertebrate consumer in response to different nutritional stressors.

Nutrient imbalances in zooplankton are caused by the differences in elemental content of producers and the demand for elements in consumers, which alter the life-history traits in consumers. Changes in life-history traits are mediated through metabolic pathways that affect gene expression and the metabolome. However, less is known about proteomic changes to elemental-limitation in zooplankton. Here, we grewDaphnia pulexunder high food quantity and quality (HF), low food quantity (LF), and phosphorus (P)-limited (PL) diets for six days and measured growth, elemental composition, and the proteome. Daphnids in both LF and PL diets grew less. Animals in LF diets had less carbon (C), while daphnids in PL diets had less P compared to HF fed animals. In total, we identified 1719 proteins that were used in a partial least squares regression discriminant analysis (PLS-DA). Focusing on a subset of the proteome, the PLS-DA resulted in a clear separation between animals fed HF diets and PL and LF diets. Many proteome changes in nutrient-limited diets are associated with growth, reproduction, lipid metabolism, and nutrient assimilation. Regardless of the limiting nutrient, there were less hemoglobin and small subunit processome component proteins compared to HF fed animals. Daphnids fed LF diets had less vitellogenin fused superoxide dismutase and more lipid-droplet hydrolase, whereas Daphniafed PL diets had higher abundances of cytochrome P450 and serine protease. Our proteome results compliment other "omic" studies that could be used to study Daphnia physiology in lakes.

The Effect of DNAJB3 Deficiency on Metabolic Dysfunctions in Diet-induced Obese Mice

Abstract Objectives Obesity and related metabolic dysfunctions are partly mediated by chronic low-grade inflammation and altered expression of numerous proteins including stress responsive heat shock proteins (HSPs). We are specifically interested in HSP40 (Heat Shock Protein-40), subfamily B, member 3 (DNAJB3), a chaperone protein that aids in restoring protein homeostasis. Patients with obesity and type 2 diabetes (T2D) expressed low levels of DNAJB3, which was partly restored by physical activity. Accordingly, we hypothesized that lack of DNAJB3 will increase body weight, inflammation, glucose intolerance and insulin resistance in diet-induced obese mice, compared to B6 wild type (WT) littermates fed the same diets. Methods DNAJB3 knockout (KO) mice were generated using the CRISPR/Cas 9 approach. Male and female KO and wild type (WT) mice were fed high fat (HF: 45 kcal% fat) or low fat (LF: 10 kcal% fat) diets for 12 weeks. Body weight and food intake were measured weekly; body composition measurements and glucose tolerance tests were also conducted during the intervention. Following euthanasia, blood, and tissues were harvested for further analyses. Serum adipokines and hormones were measured using a multiplex immunoassay. Results Compared to WT male and female, KO mice fed HF diets demonstrated higher body weight and fat mass. Similarly, both male and female KO HF groups demonstrated a slower glucose clearance rate as measured by GTT compared to the LF KO and WT groups as well as HF WT groups. Interestingly, these findings were more significant across the board in the female HF-KO group. Female HF group demonstrated a higher leptin, IL-6 and Insulin levels compared to the other groups (p < 0.0001). Additionally, Male Leptin and Resistin levels were higher in the HF-KO group compared to the other groups (p = 0.0001, p = 0.0253). Conclusions Lack of DNAJB3, increases adiposity and glucose intolerance in diet-induced obese male and female mice. Thus, DNAJB3 potentially plays an important role in metabolic functions and glucose homeostasis, warranting further research on DNAJB3 as a potential therapeutic target for obesity and T2D. Funding Sources Funded by Qatar National Research Funds, Hamad Bin Khalifa University & Qatar Biomedical Research Institute, Qatar.

Metabolic Effects of Dietary pH, Protein Source and Fat Content in Diet-induced Obese Mice

Abstract Objectives Higher intake of saturated fats, salts, and fatty proteins has been linked to metabolic diseases (e.g., obesity), in part through low-grade metabolic acidosis and inflammation. Hence, our objective was to test the effects of protein sources and preparations in diet induced obese B6 male and female mice, compared to low fat-fed mice. We hypothesized that metabolic health will be improved by consuming a diet containing pH-enhanced beef or casein diets, compared to a non-pH-enhanced diets. Methods B6 male and female mice were randomized (n = 10) into 8 diets that differ in protein source, pH enhancement, and fat content: low fat casein (LFC), pH-enhanced (with ammonia) LFC (LFCN), LF lean beef (LFB), LFBN, high fat casein (HFC), HFCN, HF beef (HFB), HFBN. Body weight and food intake were measured weekly for 12 weeks. White adipose tissue (WAT) was collected at study termination and used for histology, RNA and protein isolation for analyses of fat cell size, and gene (qRT-PCR) and protein (Western blotting) expression. Three-way ANOVA was performed to identify main effects as well as interactions of dietary pH x protein source x fat content, separately in males, and females. Results We identified a significant main effect of diet (LF/HF) on fat pad weights in males (F (1,71) = 91.94, p < 0.0001) and females (F (1,72) = 5.111, p = 0.0268). No effect of protein source or change of dietary pH was observed on fat pad weights. However, WAT histology indicated a substantial change in adipose tissue quality, with reduced adipocyte area (p < 0.05) in LF, LFN, HFCN, HFB, HFBN groups compared to HFC in males. Additionally, in both males and females, protein levels of pAkt and pAMPK were upregulated in adipose tissue of mice fed HF diets with increased pH (HFCN, HFBN), compared to non-pH enhanced HF diets. Conclusions Our findings indicate potential metabolic benefits of increasing dietary pH, as shown by improved adipose tissue cellularity and improved insulin signaling and energy sensing/fat oxidation-related markers. Thus, additional research is warranted to determine mechanisms underlying the metabolic effects of pH enhancement. These findings also merit further mechanistic studies in animals, as well as future clinical research to translate our results into humans and dissect interactions between protein source, pH and fat content on metabolic diseases. Funding Sources Empirical Foods.

Polylactose Exhibits Prebiotic Activity and Reduces Adiposity and Nonalcoholic Fatty Liver Disease in Rats Fed a High-Fat Diet

Prebiotic dietary fibers change the intestinal microbiome favorably and provide a health benefit to the host. Polylactose is a novel fiber, synthesized by extrusion of lactose. We evaluated its prebiotic activity by determining its fermentability, effect on the microbiota, and effects on adiposity and liver lipids in a diet-induced obesity animal model. Male Wistar rats (4-5 wk old) were fed normal-fat (NF, 25% fat energy) or high-fat (HF, 51% fat energy) diets containing different fibers (6% fiber of interest and 3% cellulose, by weight), including cellulose (NFC and HFC, negative and positive controls, respectively), polylactose (HFPL), lactose matched to residual lactose in the HFPL diet, and 2established prebiotic fibers: polydextrose (HFPD) and fructooligosaccharide (HFFOS). After 10 wk of feeding, organs were harvested and cecal contents collected. HFPL animals had greater cecum weight (3 times greater than HFC) and lower cecal pH (∼1pH unit lower than HFC) than all other groups, suggesting that polylactose is more fermentable than other prebiotic fibers (HFPD, HFFOS; P <0.05). HFPL animals also had increased taxonomic abundance of the probiotic species Bifidobacterium in the cecum relative to all other groups (P <0.05). Epididymal fat pad weight was significantly decreased in the HFPL group (29% decrease compared with HFC) compared with all other HF groups (P <0.05) and did not differ from the NFC group. Liver lipids and cholesterol were reduced in HFPL animals when compared with HFC animals (P <0.05). Polylactose is a fermentable fiber that elicits a beneficial change in the gut microbiota as well as reducing adiposity in rats fed HF diets. These effects of polylactose were greater than those of 2 established prebiotics, fructooligosaccharide and polydextrose, suggesting that polylactose is a potent prebiotic.

90 Effect of supplemental threonine on growth performance of pigs challenged with Salmonella typhimurium and fed high fiber diets

Abstract In a previous study, high dietary fiber (DF) and immune stimulation with systemic E. coli lipopolysaccharide independently, but not additively, increased the threonine (Thr) requirement for protein deposition. The current study investigated whether supplementing Thr to meet high DF and systemic immune challenge requirements would maintain performance of pigs exposed to an enteric immune challenge when fed high DF. A total of 128 pigs (22.6 ± 1.6 kg initial BW) were assigned to 1 of 4 dietary treatments (n = 8 pens/treatment; 4 pigs/pen) for 28 d. Treatments were low fiber (LF; 13% total DF) or high fiber (HF; 20% total DF) diets with standard (STD; 0.65% SID) or supplemental (SUP; 0.78% SID) Thr. After a 7-d adaptation, all pigs were orally inoculated with Salmonella typhimurium (2.3 × 109 CFU/ml). Blood samples and rectal swabs were obtained and rectal temperature recorded to determine clinical responses and Salmonella shedding. On d 7 post-inoculation, 1 pig/pen was euthanized and mesenteric lymph nodes, spleen and digesta (ileum, cecum, and colon) were sampled to assess Salmonella colonization and translocation. Body weight and feed intake were measured on d 0, 7, and 21 to calculate ADG, ADFI, and G:F. Rectal temperature increased (P &amp;lt; 0.05) 24 h post-inoculation and remained elevated at d 6. Serum albumin concentration decreased (P &amp;lt; 0.05), whereas haptoglobin concentration increased (P &amp;lt; 0.05) post-inoculation. Fiber and Thr had no effect (P &amp;gt; 0.05) on Salmonella count in ileum and cecum. Supplemental Thr increased (P &amp;lt; 0.05) growth performance in LF- and HF-fed challenged pigs. However, performance of supplemented HF challenged pigs was less than (P &amp;lt; 0.05) supplemented LF challenged pigs. These results suggest that Thr supplemented to meet requirements for high DF and systemic immune challenge was not sufficient to maintain growth performance of pigs fed HF diets and challenged with an enteric pathogen.

Effect of supplemental threonine above requirement on growth performance of Salmonella typhimurium challenged pigs fed high-fiber diets1.

It was shown previously that high dietary fiber (DF) and immune system stimulation (ISS) with systemic Escherichia coli lipopolysaccharide independently increased the threonine (Thr) requirement to maximize growth performance and protein deposition (PD). However, no additive effects on the Thr requirement were observed when both DF and ISS were present. The objective of the present study was to investigate whether supplementing Thr to meet previously estimated requirements for high DF and systemic immune challenge would maintain performance of pigs exposed to an enteric immune challenge when fed high DF. A total of 128 pigs (22.6 ± SD = 1.6 kg initial BW) were assigned to 1 of 4 dietary treatments in a 2 × 2 factorial arrangement in a randomized complete block design (n = 8 pens/treatment and 4 pigs/pen) for 28 d. Treatments were a low-fiber (LF; 13% total DF) or high-fiber (HF; 20% total DF) diet with either a standard (STD; 0.65% SID) or supplemental (SUP; 0.78% SID) Thr level. After a 7-d adaptation, pigs were orally inoculated with 2 mL (2.3 × 109 CFU/mL) of Salmonella typhimurium (ST). Blood samples and rectal swabs were obtained and rectal temperature recorded to determine clinical responses and ST shedding. On day 7 postinoculation, 1 pig/pen was euthanized and mesenteric lymph nodes, spleen, and digesta (ileum, cecum, and colon) were sampled to assess ST colonization and translocation. Body weight and feed intake were recorded on day 0, 7, and 21 postinoculation to calculate ADG, ADFI, and G:F. Rectal temperature increased (P < 0.05) 24 h postinoculation and remained elevated at day 6. Serum albumin concentration decreased (P < 0.05), whereas haptoglobin concentration increased (P < 0.05) postinoculation. There was no fiber or Thr effect (P > 0.05) on ST counts in the ileum and cecum, but a fiber × Thr interaction (P < 0.05) was observed in the colon. Supplemental Thr improved (P < 0.05) growth performance in LF- and HF-fed challenged pigs. However, performance of supplemented HF challenged pigs was less than (P < 0.05) supplemented LF challenged pigs. These results suggest that Thr supplemented to meet requirements for high DF and systemic immune challenge was not sufficient to maintain growth performance of pigs fed HF diets and challenged with an enteric pathogen.

Eicosapentaenoic Acid Increases Browning Markers in Subcutaneous Adipose Tissue and Primary Adipocytes from Wild Type and UCP-1 Deficient Mice (P15-007-19)

ObjectivesBrown adipose tissue (BAT) regulates energy balance through thermogenesis, in part via uncoupling protein -1 (UCP-1). White adipose tissue (WAT), namely subcutaneous adipose tissue (SAT) can convert to a beige/brite adipose tissue phenotype (browning) under thermogenic conditions such as cold. We previously reported that eicosapentaenoic acid (EPA) reduced obesity and glucose intolerance, and increased UCP-1 in BAT of B6 mice at ambient temperature (22°C); and these effects were attenuated at thermoneutral environment (28–30°C). We hypothesized that EPA exerts anti-obesity effects on SAT, including increased browning, adipocyte hypotrophy; and these effects require UCP-1. MethodsSix-week-old B6 wild type (WT) and UCP-1 knock-out (KO) male mice were maintained at thermoneutral environment and fed high fat diet (HF) with or without 36 g/kg of AlaskOmega EPA-enriched fish oil (800 mg/g) for 14 weeks; and SAT was collected for histological, gene and protein analyses. SAT was also prepared from chow diet-fed WT and KO mice at ambient environment to prepare stroma vascular cells, which were differentiated into adipocytes, treated with 100uM EPA for 48 hours then harvested for mRNA and protein analyses. ResultsKO mice fed HF diets had the highest body weight (P < 0.05) among all groups. EPA reduced fat cell size in both WT and KO mice fed the EPA diet. mRNA levels of fibroblast growth factor-21 (FGF-21) were higher in SAT of WT mice fed EPA compared to WT mice fed HF (P < 0.05), with no differences between the KO genotype. KO mice fed HF diets had lower levels of UCP-3 in SAT compared to WT mice fed HF (P < 0.05), which was rescued only in the KO mice fed EPA (P < 0.05). UCP-1 protein levels were very low in SAT tissues, and UCP-2 mRNA levels were similar across all groups in SAT. Interestingly, EPA significantly (P < 0.05) increased mRNA expression of UCP-2, UCP-3 and FGF21 in differentiated SAT adipocytes from both WT and KO compared to control. Furthermore, UCP-1 mRNA levels were significantly higher in WT adipocytes treated with EPA, compared to non-treated cells (P < 0.05). Additional mechanistic studies are currently underway to further dissect adipose depot differences in EPA effects in WT vs. KO mice. ConclusionsOur data suggest that EPA increases SAT browning, independently of UCP-1. Funding SourcesNIH/NCCIH.

Effects of distillers dried grains with solubles and forage dietary concentration in precision-fed dairy heifer diets: Mineral apparent absorption and retention

ABSTRACT Objective The objectives were to determine the effects of feeding different forage-to-concentrate ratios (F:C) and corn distillers dried grains with solubles (DDGS) inclusion rates on mineral apparent absorption (AAb) and retention in precision-fed dairy heifer rations. Materials and Methods A split plot design with F:C as whole plot [50:50 (LF) or 75:25 (HF)] and DDGS concentration as subplot (0, 7, 14 and 21%) was administered in a 4 × 4 Latin square using 8 ruminally cannulated Holstein heifers (12.5 ± 0.5 mo of age and 344 ± 15 kg of BW), and targeted an ADG of 800 g/d. Results and Discussion Mineral intake was affected by F:C and DDGS; there was a linear interaction in DMI. Fecal excretion of Mg, S, and Mn was greater for heifers fed HF diets, and fecal Ca, Mg, P, S, and Mn decreased linearly with increasing DDGS. Urinary excretion of Mg was greater for LF and decreased as DDGS increased. The AAb of Mg, S, and Mn was greater for LF. Linear and quadratic interactions between F:C and DGGS in AAb were observed for S and Mg, respectively. Retention of Mg was greater in LF; no differences were detected for Ca, K, Na, and S retention with F:C or DDGS. Linear interactions between F:C and DGGS were observed in the retention of Mg, P, and S. Linear and quadratic interactions in AAb for Mg and S, respectively, and a linear interaction for Mg, P, and S rentention demonstrate the importance of digestion kinetics when different F:C are used to evaluate dietary manipulations. Implications and Applications There was a linear reduction of Ca, Mg, P, S, and Mn fecal excretion in response to the linear reduction of DMI as DDGS were incorporated in diets. Heifers fed high forage diets had greater DMI and rate of passage resulting in small increases in Mg, S, and Mn excretion in feces. Absorption and retention of most minerals, notably Ca, K, Na, and P, were not affected by dietary levels of DDGS.

Phosphorus restriction does not prevent the increase in fibroblast growth factor 23 elicited by high fat diet.

This study was designed to evaluate the influence of phosphorus (P) restriction on the deleterious effects of high fat diets on mineral metabolism. Twenty-four rats were allotted to 3 groups (n = 8 each) that were fed different diets for 7 months. Rats in group 1 were fed normal fat-normal P (0.6%) diet (NF-NP), rats in group 2 were fed high fat- normal P diet (HF-NP) and rats in group 3 were fed high fat-low P (0.2%) diet (HF-LP). Blood, urine and tissues were collected at the end of the experiments. When compared with the control group (NF-NP), rats fed HF diets showed increases in body weight, and in plasma concentrations of triglycerides and leptin, and decreased plasma calcitriol concentrations. In rats fed HF-NP plasma fibroblast growth factor 23 (FGF23) was higher (279.6±39.4 pg/ml vs 160.6±25.0 pg/ml, p = 0.018) and renal klotho (ratio klotho/GAPDH) was lower (0.75±0.06 vs 1.06±0.08, p<0.01) than in rats fed NF-NP. Phosphorus restriction did not normalize plasma FGF23 or renal klotho; in fact, rats fed HF-LP, that only ingested an average of 22.9 mg/day of P, had higher FGF23 (214.7±32.4 pg/ml) concentrations than rats fed NF-NP (160.6±25.0 pg/ml), that ingested and average of 74.4 mg/day of P over a 7 month period. In conclusion, our results demonstrate that severe P restriction over a prolonged period of time (7 months) does not normalize the increase in circulating FGF23 induced by HF diets. These data indicate that the deleterious effects of high fat diet on the FGF23/klotho axis are not eliminated by reduced P intake.

Lactation performance of dairy cows fed yeast-derived microbial protein in low- and high-forage diets

The objective of this study was to investigate the effect of substituting soybean meal products with yeast-derived microbial protein (YMP) on lactation performance in diets containing 2 forage-to-concentrate ratios. Sixteen Holstein cows (4 primiparous and 12multiparous) were randomly assigned to multiple 4×4 Latin squares with a 2×2 factorial arrangement of treatments. Diets contained low (LF; 45% of diet DM) or high forage (HF; 65% of diet DM) and YMP at 0 (NYMP) or 2.25% (WYMP) of the diet. The forage mix consisted of 67% corn silage and 33% alfalfa hay on a DM basis. No interactions of forage and YMP were noted for any of the production parameters measured. Feed efficiency (energy-corrected milk/dry matter intake) was greater for cows fed NYMP compared with WYMP. Regardless of the addition of YMP, cows fed LF had greater dry matter intake and produced more milk than cows fed HF. In addition, cows fed LF produced more energy-corrected milk than those fed HF. Milk fat percentage was lower in cows fed LF compared with HF, whereas fat yield was similar between forage concentrations. Fat yield tended to decrease with feeding YMP. Interactions of forage and YMP were observed for propionate concentration, acetate and propionate proportion, and acetate-to-propionate ratio. A tendency for an interaction of forage and YMP was also noted for ruminal pH. Cows fed HF diets had greater ruminal ammonia and butyrate concentrations, as well as proportion of butyrate. Arterial concentrations of Ile, Leu, Met, Thr, and Val were greater in cows fed LF. Cows fed NYMP had greater arterial concentrations of Ile, Lys, Trp, and Val than cows fed WYMP. Substitution of soybean proteins with YMP did not improve performance or feed efficiency of high-producing dairy cows regardless of the forage-to-concentrate ratio of the diet.

Dietary fat and carbohydrate have different effects on body weight, energy expenditure, glucose homeostasis and behaviour in adult cats fed to energy requirement.

The effects of dietary carbohydrate and fat on feline health are not well understood. The effects of feeding diets moderately high in fat (HF; n 10; 30 % fat, 26 % carbohydrate as fed) or carbohydrate (HC; n 10; 11 % fat, 47 % carbohydrate), for 84 d, were investigated in healthy, adult cats (3·5 (sd 0·5) years). Data on indirect calorimetry, blood biomarkers, activity, play and cognition were collected at baseline, and at intervals throughout the study. Body composition was measured by dual-energy X-ray absorptiometry at baseline and on day 85. There were no significant main effects of diet on body weight and composition. When data were analysed over study day within diet, cats fed HF diets experienced a significant increase in body fat (P=0·001) and body weight (P=0·043) in contrast to cats consuming the HC diet that experienced no change in body fat or body weight (P=0·762) throughout the study. Overall, energy expenditure was similar between diets (P=0·356 (fasted), P=0·086 (postprandial)) and respiratory quotient declined with exposure to the HF diet and increased with exposure to the HC diet (P<0·001; fasted and postprandial). There was no difference in insulin sensitivity as an overall effect of diet (P=0·266). Activity declined from baseline with exposure to both diets (HC: P=0·002; HF: P=0·01) but was not different between diets (P=0·247). There was no effect of diet on play (P=0·387) and cats consuming either the HF or HC diet did not successfully learn the cognitive test. Overall, cats adapt to dietary macronutrient content, and the implications of feeding HC and HF diets on risk for adiposity as driven by metabolic and behavioural mechanisms are discussed.

Dietary Anthocyanin-rich Haskap Phytochemicals Inhibit Postprandial Hyperlipidemia and Hyperglycemia in Rats

Haskap (Lonicera caerulea L.) fruit contains some bioactive phenolic phytochemicals, mainly cyanidin-3-glucoside (cy3-glc) and chlorogenic acid. The purpose of this study was to investigate the effects of anthocyanin-rich phenolic phytochemical (containing 13.2% anthocyanin) purified from a Haskap fruit (named Haskap phytochemical) on postprandial serum triglyceride and blood glucose levels. The Haskap phytochemical (containing cy 3-glc at 300 mg/kg of body weight) was administered orally to rats fasted for 24 h and 30 min later, a corn oil emulsion was administered to these rats. After the administration, serum triglyceride concentration was measured. An increase in serum triglyceride concentration and the AUC significantly lowered in the Haskap phytochemical-administered group than in the saline-administered group. To evaluate the effect of serum glucose levels, the Haskap phytochemical was orally administered to rats fasted for 24 h and sucrose solution (2 g/kg of body weight) was administered to these rats after 30 min. After the administration, blood glucose level was measured. The Haskap phytochemical significantly reduced the increase in blood glucose levels and AUC in the Haskap phytochemical-administered group than in the saline-administered group. Furthermore, to investigate the long-term effects of Haskap phytochemical intake, high-fat diet (HF diet) with 1.5% or 3.0% Haskap phytochemical was administered to rats for four weeks. The investigation of chronological changes in the serum components of the rats fed HF diets in addition to the administration of Haskap phytochemical showed that the increase in serum triglyceride concentrations, total cholesterol concentrations and blood glucose were significantly suppressed compared to the HF diet-fed control (HF-control). These results suggest that the decrease in postprandial blood lipids and blood glucose by short or long-term Haskap phytochemical ingestion is due to anthocyanin and other polyphenols contained in the Haskap phytochemical.

Maternal high-fat diet is associated with altered pancreatic remodelling in mice offspring

To investigate whether a maternal high-fat diet (HF) during pregnancy and/or suckling periods predisposes adult C57BL/6 mice offspring to morphological pancreatic modifications. Male pups were divided into 5 groups: SC (standard chow)-from dams fed SC during gestation and lactation, maintaining an SC diet from postweaning to adulthood; G-from dams fed HF diets during gestation; L-from dams fed HF diets during lactation; GL-from dams fed HF diets during gestation and lactation; and GL/HF-from dams fed HF diets during gestation and lactation, maintaining an HF diet from postweaning to adulthood. We analysed body mass (BM), plasma insulin, pancreas and adipose tissue structures. During the entire experiment, the SC group had the lowest BM. However, GL/HF offspring were heavier than the other groups. This weight gain was also accompanied by adipocyte hypertrophy. At 3 months, G offspring showed an increased insulin levels and impairment in carbohydrates metabolism. Furthermore, pancreatic islets were hypertrophied in G, GL and GL/HF offspring in comparison with SC offspring. HF diet administration during the gestation period is more harmful than during the lactation period, exerting deleterious effects on pancreatic morphology in addition to larger fat deposits in adult mice offspring.

Comparison of fermentation of diets of variable composition and microbial populations in the rumen of sheep and Rusitec fermenters. II. Protozoa population and diversity of bacterial communities

Four ruminally and duodenally cannulated sheep and 8 Rusitec fermenters were used to determine the effects of dietary characteristics on microbial populations and bacterial diversity. The purpose of the study was to assess how closely fermenters can mimic the differences between diets found in vivo. The 4 experimental diets contained forage to concentrate (F:C) ratios of 70:30 (high forage; HF) or 30:70 (high concentrate; HC) with either alfalfa hay (A) or grass hay (G) as the forage. Total bacterial numbers were greater in the rumen of sheep fed HF diets compared with those fed HC diets, whereas the opposite was found in fermenters. The numbers of cellulolytic bacteria were not affected by F:C ratio in any fermentation system, but cellulolytic numbers were 2.7 and 1.8 times greater in sheep than in fermenters for HF and HC diets, respectively. Neither total bacterial nor cellulolytic numbers were affected by the type of forage in sheep or fermenters. Decreasing F:C ratio increased total protozoa and Entodiniae numbers in sheep by about 29 and 25%, respectively, but it had no effect in fermenters. Isotrichidae and Ophryoscolecinae numbers in sheep were not affected by changing F:C ratio, but both disappeared completely from fermenters fed HC diets. Total protozoa and Entodiniae numbers were greater in sheep fed A diets than in those fed G diets, whereas the opposite was found in fermenters. Results indicate that under the conditions of the present study, protozoa population in Rusitec fermenters was not representative of that in the rumen of sheep fed the same diets. In addition, protozoa numbers in fermenters were 121 and 226 times lower than those in the sheep rumen for HF and HC diets, respectively. The automated ribosomal intergenic spacer analysis of the 16S ribosomal DNA was used to analyze the diversity of liquid- and solid-associated bacteria in both systems. A total of 170 peaks were detected in the automated ribosomal intergenic spacer analysis electropherograms of bacterial pellets across the full set of 64 samples, from which 160 were detected in at least 1 individual from each system (sheep or fermenter). Diversity of liquid-associated bacterial pellets was greater with G diets in fermenters but seemed to be unaffected by diet in sheep. Bacterial diversity in solid-associated bacteria pellets was greater for G diets compared with A diets in sheep and fermenters. Different conditions in the fermenters compared with sheep rumen might have caused a selection of some bacterial strains.

Effect of level of fibre and type of grinding on the performance of rabbit does and their litters during the first three lactations

To study the effects of fibre level and particle size on rabbit performance, four diets in a 2 × 2 factorial arrangement were used with high (HF) and low (LF) fibre level (34 vs. 27% NDF, % DM) and coarse (CG) and normal (NG) type of grinding of the main sources of fibre (alfalfa hay and wheat straw). This resulted in a proportion of particles > 0.3 mm of 35, 24, 24 and 20% (on DM basis) for HF-CG, HF-NG, LF-CG and LF-NG diets, respectively. HF diets contained 4.2% pork lard to balance the digestible energy/protein ratios. Seventy two nulliparous rabbit does were randomly assigned to the diets (18 per diet) and controlled up to their fourth parturition. Remating interval was fixed at four days after parturition and weaning age at 25 days. Twenty does died or were culled during the experiment because of low prolificacy and infertility. CG diets reduced culling level from 22 to 2.8% ( P = 0.008) compared to NG diets. Digestible energy (DE) intake was not affected by treatments during lactation or among parturitions. However, an interaction NDF level × type of grinding was observed for feed and DE intake from weaning to parturition, as rabbit does fed HF-NG and LF-CG diets ate 10% more feed ( P = 0.040) and DE ( P = 0.053), and showed a shorter parturition-effective mating interval (− 5.3 days, P = 0.028) than those fed HF-CG and LF-NG. Animals fed LF-NG tended to have the lowest feed efficiency among parturitions ( P = 0.079). In rabbits fed LF, total milk production and litter growth rate from birth to 21 days decreased by 9% compared to those fed HF diets that included added fat ( P ≤ 0.013). Litters from rabbit does fed LF or NG diets increased ( P ≤ 0.040) their feed intake from 21 to 25 days, avoiding differences among treatments in litter weight gain during lactation. Post-weaning feed efficiency was less with LF diets ( P = 0.045). Thus, fineness of grinding of fibre sources should therefore be taken into account, especially in low fibre diets to optimize rabbit doe performance.

Microbial protein synthesis, ruminal digestion, microbial populations, and nitrogen balance in sheep fed diets varying in forage-to-concentrate ratio and type of forage1

Six ruminally and duodenally cannulated sheep were used in a partially replicated 4 x 4 Latin square to evaluate the effects of 4 diets on microbial synthesis, microbial populations, and ruminal digestion. The experimental diets had forage to concentrate ratios (F:C; DM basis) of 70:30 (HF) or 30:70 (HC) with alfalfa hay (A) or grass hay (G) as forage and were designated as HFA, HCA, HFG, and HCG. The concentrate was based on barley, gluten feed, wheat middlings, soybean meal, palmkern meal, wheat, corn, and mineral-vitamin premix in the proportions of 22, 20, 20, 13, 12, 5, 5, and 3%, respectively (as-is basis). Sheep were fed the diets at a daily rate of 56 g/kg of BW(0.75) to minimize feed selection. High-concentrate diets resulted in greater (P < 0.001) total tract apparent OM digestibility compared with HF diets, but no differences were detected in NDF digestibility. Ruminal digestibility of OM, NDF, and ADF was decreased by increasing the proportion of concentrate, but no differences between forages were detected. Compared with sheep fed HF diets, sheep receiving HC diets had less ruminal pH values and acetate proportions, but greater butyrate proportions. No differences among diets were detected in numbers of cellulolytic bacteria, but protozoa numbers were less (P = 0.004) and total bacteria numbers tended (P = 0.08) to be less for HC diets. Carboxymethylcellulase, xylanase, and amylase activities were greater for HC compared with HF diets, with A diets showing greater (P = 0.008) carboxymethylcellulase activities than G diets. Retained N ranged from 28.7 to 37.9% of N intake and was not affected by F:C (P = 0.62) or the type of forage (P = 0.31). Microbial N synthesis and its efficiency was greater (P < 0.001) for HC diets compared with HF diets. The results indicate that concentrates with low cereal content can be included in the diet of sheep up to 70% of the diet without detrimental effects on ruminal activity, microbial synthesis efficiency, and N losses.

Effects of fibre level and dietary mannanoligosaccharides on digestibility, caecal volatile fatty acids and performances of growing rabbits

The current experiment with 3 trials aimed to study the effect of two levels of dietary fibre – high fibre (HF; 323 g aNDFom/kg) and low fibre (LF; 248 g aNDFom/kg) – and the effect of mannanoligosaccharides (MOS) addition (1 g/kg) to the LF diet (LFM) on the performances and health status of growing rabbits, digestibility and caecal fermentative characteristics. In the growth trial 132 rabbits of both sexes were used (11 cages with 4 rabbits per treatment) from weaning (32 days of age) to slaughter (67 days of age). Rabbits fed HF diet showed a significantly higher weight gain and live weight at 67 days than rabbits fed LF diet (2032 g vs. 1935 g) (P<0.05). Feed and digestible energy intake increased with dietary fibre level (P<0.05). During the growing period rabbits fed HF diet had a feed intake 26% higher than those fed LF diet. Feed efficiency ratio was worse in HF animals (0.334 vs. 0.385; P<0.05). Addition of MOS to LF diet did not affect growth performance parameters (P>0.05). Mortality and morbidity rate were not affected by treatments. In the digestibility 24 rabbits from 46 to 51 days of age trial were used. The HF diet resulted in a significant (P<0.05) decrease in digestibility of dry matter, organic matter and protein while the aNDFom digestibility was not significantly different between diets (P>0.05). Supplementation with MOS had no effects on digestibility (P>0.05). In the 3rd trial the caecal traits were measured in 30 rabbits with 46 days of age that received the experimental diets in the previous 14 days. Caecal production of total volatile fatty acids (VFA), acetate and propionate were significantly higher (P>0.05) on rabbits fed HF diets than on rabbits fed LF diets. The total VFA concentration increased 64% (from 5.01 to 8.20 mmol/100 ml) and acetate increased 73% (from 3.73 to 6.44 mmol/100 ml). Butyrate production was not different between diets (P>0.05). Fibre level did not affect proportions of VFA and caecal contents and caecal weights. Addition of MOS to LF diet did not affect any caecal trait (P>0.05). It was concluded that the reduction of dietary fibre level increases feed digestibility but worsens rabbit growth performances. Supplementation of low fibre diet with 1 g MOS/kg is not enough to reduce its negative effects on growth performances.

Caloric intake and dietary fat to carbohydrate ratio influence body weight accretion and adiposity in rats fed by total enteral nutrition

Consumption of high energy high-fat diets leads to weight gain and adiposity in rodents. However the relative roles of higher caloric intake vs. increased dietary fat remain unclear. Low carbohydrate high fat diets, like the Atkins diet, claim to promote weight loss. We employed a total enteral nutrition model to evaluate roles of caloric intake and dietary fat to carbohydrate ratio in mediating weight gain. Female Sprague-Dawley rats were fed either 187 kcal/kg3/4/d (normal calorie, NC, NRC requirements) or 220 kcal/kg3/4/d (overfed 15% excess calories/d, high calorie, HC) via intragastric infusion. NC and HC diets were either low fat (LF, 5% calories from fat, corn oil) or high fat (HF, 45% calories from fat, ~20-fold higher fat/carbohydrate than LF). LF and HF diets were isocaloric. Protein (casein) was 20% of caloric intake and carbohydrate calories contributed to 75% and 35% in the LF and HF diets, respectively. A separate group of rats were fed regular rodent chow (ad libitum). After 6 weeks of infusion of diets, body weights (BW) of rats fed NC-HF matched ad lib fed controls. HC-HF rats showed significantly higher (152%) BW compared to NC-HF and ad lib fed controls. However, both NC and HC rats fed LF diets consistently showed ~20% higher BW compared to rats fed HF diets. Consistent with BW data, body composition as assessed by Echo MRI revealed higher fat mass/BW in rats fed HC diets. Greater fat mass/BW was also observed in NC-LF rats as compared to NC-HF fed rats. Analysis of oral glucose tolerance tests to evaluate insulin resistance as a function of caloric and diet fat intake is ongoing. Supported in part by ARS CRIS #6251-51000-003-065

Positional characteristics of triacylglycerol in soft-shelled turtle oil and its effects on lipid metabolism in hamsters fed a high fat diet

Soft-shelled turtle is a highly economic species and plays a mystical role in traditional Chinese medicine. The present study analyzed the positional distribution in triacylglycerol (TG) of soft-shelled turtle oil (STO) and its effects on lipid metabolism in hamsters fed a high fat diet. Analysis showed that TG made up the maximum fragments among lipid classes of STO, with eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) integrated in the sn-1,3 position of TG. For the animal study, forty male hamsters were randomly divided into five groups and fed a control diet (5% fat), high fat diet (HF, 10% fat) and HF diets containing 2% (STO2), 4% (STO4) or 6% (STO6) soft-shelled turtle oil for 28 days. The body weight gain and food intakes were comparable between hamsters fed HF diet and HF diet containing STO from 2% to 6% during the experiment. Hamsters fed HF diets containing 2–6% STO showed decreased liver TG, and HF diets containing 4% or 6% STO showed decreased serum TG but increased serum total cholesterol. In addition, enzyme activities of lipogenesis in hepatic malic enzyme and glucose-6-phosphate dehydrogenase were lower in hamsters fed 4% or 6% STO than in those fed the high fat diet. These results suggest that dietary 4% or 6% STO, with different intramolecular distributions of n-3 PUFA, might decrease serum and liver TG concentrations by diminishing enzyme activities involved in liver fatty acid synthesis.

Effects of dietary fatty acids and exercise on body-weight regulation and metabolism in rats.

To assess the interaction of high-fat diets (HF) made with different dietary fatty acids and exercise on body-weight regulation, adiposity, and metabolism. Male Wistar rats born to dams fed HF diets (40% w/w) made with either fish oil (FO), soybean oil (SO), or palm oil (PO) were fed diets similar to their dams and divided randomly into exercise (EX, swimming) or sedentary control (SD) groups when they were 9 weeks old. EX lasted for 6 weeks. Twenty-four hours after the last EX bout, fasted rats were killed by decapitation. Chemical analyses and body composition analysis were conducted. The results demonstrated that different fatty acids had different effects on body weight, composition, and metabolism. SO-fed rats gained the most weight and fat. EX reduced body weight of FO- and PO-fed rats, but SO-fed rats were still heavier and fatter than other rats. Data from SO- and PO-fed rats suggested that they are insulin resistant and that EX normalized this abnormality. Of the three HF diets used, FO produced the least adverse effects compared with PO and SO. Not only the quantity of dietary fat, but also the type of fat used, will produce different effects on body weight and metabolism. EX ameliorates the suggested insulin resistance induced in rats fed either highly saturated or n-6 polyunsaturated fatty acids. Long-chain n-3 polyunsaturated fatty acids, as found in fish oil, are more beneficial than n-6 polyunsaturated fatty acids when fed in high amounts to rats.