Serum Lipid, Amino Acid and Acylcarnitine Profiles of Obese Cats Supplemented with Dietary Choline and Fed to Maintenance Energy Requirements

Minimum methionine requirement in adult cats as determined by indicator amino acid oxidation

There is a lack of empirical data on the dietary Met requirement, in the presence of Cys or cystine, in adult cats. Thus, the aim of this study was to determine the Met requirement, in the presence of excess Cys, in adult cats at maintenance using the indicator amino acid oxidation (IAAO) technique. Six adult neutered male cats were initially selected and started the study. Cats were adapted to the basal diet sufficient in Met (0.24% dry matter, DM) for 14 d prior to being randomly allocated to one of eight dietary levels of Met (0.10%, 0.13%, 0.17%, 0.22%, 0.27%, 0.33%, 0.38%, and 0.43% DM). Different dietary Met concentrations were achieved by supplementing the basal diet with Met solutions. Alanine was additionally included in the solutions to produce isonitrogenous and isoenergetic diets. Cats underwent a 2-d adaptation period to each experimental diet prior to each IAAO study day. On IAAO study days, 13 meals were offered corresponding to 75% of each cat's daily food allowance. The remaining 25% of their daily food intake was offered after each IAAO study. A bolus dose of NaH13CO3 (0.44 mg kg-1) and l-[1-13C]-phenylalanine (13C-Phe; 4.8 mg kg-1) were provided in fifth and sixth meals, respectively, followed by a constant dose of 13C-Phe (1.04 mg kg-1) in the next meals. Breath samples were collected and total production of 13CO2 was measured every 25 min through respiration calorimetry chambers. Steady state of 13CO2 achieved over at least three breath collections was used to calculate oxidation of 13C-Phe (F13CO2). Competing models were applied using the NLMIXED procedure in SAS to determine the effects of dietary Met on 13CO2. Two cats were removed from the study as they did not eat all meals, which is required to achieve isotopic steady. A breakpoint for the mean Met requirement, with excess of Cys, was identified at 0.24% DM (22.63 mg kg-1) with an upper 95% confidence limit of 0.40% DM (37.71 mg·kg-1), on an energy density of 4,164 kcal of metabolizable energy/kg DM calculated using the modified Atwater factors. The estimated Met requirement, in the presence of excess of Cys, is higher than the current recommendations proposed by the National Research Council's Nutrient Requirement of Dogs and Cats, the Association of American Feed Control Officials, and the European Pet Food Industry Federation.

Dietary choline, but not L-carnitine, increases circulating lipid and lipoprotein concentrations, without affecting body composition, energy expenditure or respiratory quotient in lean and obese male cats during weight maintenance

Introduction

Due to the involvement in one-carbon metabolism and lipid mobilization, choline and L-carnitine supplementation have been recommended to minimize hepatic lipid accumulation and support fat oxidation, respectively. This study investigated the lipotropic benefits of choline or L-carnitine supplementation in lean and obese cats maintaining body weight (BW).

Methods

Lean [n = 9; body condition score (BCS): 4-5/9] and obese (n = 9; BCS: 8-9/9) adult male neutered colony cats were used in a replicated 3 x 3 complete Latin square design. Treatments included choline (378 mg/kg BW0.67), L-carnitine (200 mg/kg BW) and control (no supplement). Treatments were supplemented to the food for 6 weeks each, with a 2-week washout between treatments. Cats were fed once daily to maintenance energy requirements, and BW and BCS were assessed weekly. Fasted blood collection, indirect calorimetry, and dual-energy X-ray absorptiometry occurred at the end of each treatment period. Serum was analyzed for cholesterol (CHOL), high-density lipoprotein CHOL (HDL-C), triglycerides (TAG), non-esterified fatty acids (NEFA), glucose, creatinine (CREAT), urea, alkaline phosphatase (ALP) and alanine aminotransferase (ALT). Very low-density lipoprotein CHOL (VLDL) and low-density lipoprotein CHOL (LDL-C) were calculated. Data were analyzed using proc GLIMMIX, with group and period as random effects, and treatment, body condition, and their interaction as fixed effects, followed by a Tukey's post-hoc test when significance occurred.

Results

Cats supplemented choline had lower food intake (P = 0.025). Treatment did not change BW, BCS and body composition (P > 0.05). Obese cats had greater ALP, TAG, and VLDL, and lower HDL-C compared to lean cats (P < 0.05). Choline resulted in greater CHOL, HDL-C, LDL-C and ALT (P < 0.05). L-carnitine resulted in lower CREAT (P = 0.010). Following the post-hoc test, differences between treatment means were not present for ALP (P = 0.042). No differences were found for glucose, urea or NEFA (P > 0.05). Obese cats had a lower fed respiratory quotient (RQ), regardless of treatment (P = 0.045). Treatment did not affect fed or fasted RQ and energy expenditure (P > 0.05).

Discussion

Choline appeared to increase circulating lipid and lipoprotein concentrations regardless of body condition, likely through enhanced lipid mobilization and hepatic elimination. Neither dietary choline or L-carnitine altered body composition or energy metabolism in the lean or obese cats, as compared to control.

Partial weight reduction protocols in cats lead to better weight outcomes, compared with complete protocols, in cats with obesity

Background

To date, there have been no studies comparing outcomes of cats with obesity following either complete or partial weight reduction protocols.

Methods

Fifty-eight cats participated in this non-randomized observational cohort study, including 46 (79%) and 12 (21%) that underwent complete or partial weight reduction protocols, respectively. Weight loss outcomes, body composition changes and essential nutrient intake were compared between cats in the two groups.

Results

All cats remained healthy, and those on a complete weight reduction protocol lost a median of 23% (range 10-39%) of starting body weight (SBW) over 294 days (113-967 days), whereas those undergoing partial restriction lost 25% (10-41%) over 178 days (54-512 days). Neither duration nor percentage weight loss differed between groups, but those that followed a partial weight reduction protocol lost weight at a faster rate (0.81% per week) and required fewer visits (4-19) than those that followed a complete weight reduction protocol (0.61% per week, p = 0.028; 11, 4-40 visits, p = 0.009). Further, lean tissue mass declined in cats on a complete weight reduction protocol (pre: 4.20 kg, 2.64-5.72 kg; post: 3.90 kg, 2.76-5.24 kg, p < 0.001), whereas lean tissue mass was unchanged in cats on partial weight reduction protocols (pre: 3.45 kg, 2.79-4.71 kg; post: 3.41 kg, 2.90-4.59 kg, p = 0.109). In 33 (57%) cats, median intake of selenium per day was less than NRC AI and RA recommendations, whilst intake was under FEDIAF recommendation in 42 (72%) cats. Median intake of choline per day was less than NRC MR and RA recommendations in 22 (38%) and 53 (91%) cats, respectively, whereas it was under the FEDIAF recommendation in 51 (88%) cats. In a small proportion (12-14%) of cats, phenylalanine/tyrosine and potassium were under recommendations; besides these, no other essential nutrient deficiencies were seen, and there were no differences between cats undergoing complete and partial weight reduction.

Conclusion

Partial weight reduction protocols in cats lead to quicker average weight loss, with the possibility that lean tissue loss might be minimized. Such protocols might be more suitable for older cats and those with marked obesity.

Effects of weight loss and feeding specially formulated diets on the body composition, blood metabolite profiles, voluntary physical activity, and fecal metabolites and microbiota of overweight cats

Feline obesity is a common and preventable disease, posing a myriad of health risks and detriments. Specially formulated diets and restricted feeding may serve as an intervention strategy to promote weight loss and improve feline health. In this study, our objective was to determine the effects of restricted feeding and weight loss on body composition, voluntary physical activity, blood hormones and metabolites, and fecal microbiota of overweight cats. Twenty-two overweight adult spayed female and neutered male cats [body weight (BW) = 5.70 ± 1.0 kg; body condition score (BCS) = 7.68 ± 0.6; age = 4 ± 0.4 yr] were used in a weight loss study. A control diet (OR) was fed during a 4-wk baseline to identify intake needed to maintain BW. After baseline (week 0), cats were allotted to OR or a test diet (FT) and fed to lose ~1.0% BW/wk for 24 wk. At baseline and 6, 12, 18, and 24 wk after weight loss, dual-energy x-ray absorptiometry scans were performed and blood samples were collected. Voluntary physical activity was measured at weeks 0, 8, 16, and 24. Fecal samples were collected at weeks 0, 4, 8, 12, 16, 20, and 24. Change from baseline data were analyzed statistically using the Mixed Models procedure of SAS, with P < 0.05 considered significant. Restricted feeding of both diets led to weight and fat mass loss, lower BCS, and lower blood triglyceride and leptin concentrations. Cats fed the FT diet had a greater reduction in blood triglycerides and cholesterol than cats fed the OR diet. Restricted feeding and weight loss reduced fecal short-chain fatty acid, branched-chain fatty acid, phenol, and indole concentrations. Fecal valerate concentrations were affected by diet, with cats fed the OR diet having a greater reduction than those fed the FT diet. Fecal bacterial alpha diversity was not affected, but fecal bacterial beta diversity analysis showed clustering by diet. Restricted feeding and weight loss affected relative abundances of 7 fecal bacterial genera, while dietary intervention affected change from baseline relative abundances of 2 fecal bacterial phyla and 20 fecal bacterial genera. Our data demonstrate that restricted feeding promoted controlled and safe weight and fat loss, reduced blood lipids and leptin concentrations, and shifted fecal metabolites and microbiota. Some changes were also impacted by diet, highlighting the importance of ingredient and nutrient composition in weight loss diets.

Circulating direct infusion MS and NMR metabolomic profiles of post-gonadectomy kittens with or without additional dietary choline supplementation

Choline is beneficial for energy metabolism and growth in various species. Choline may work similarly in kittens at risk of obesity. Direct infusion MS (Di-MS) and NMR spectroscopy were used to investigate the metabolomic signatures of kittens supplemented with or without additional dietary choline for 12 weeks. Fifteen intact male kittens consumed a base diet (3310 mg choline/kg DM) to their daily metabolisable energy requirement (DER) over an 11-week acclimation. Kittens were gonadectomised and assigned, based on body weight, to the base diet (CONTROL, n 7) or the base diet with 300 mg/kgBW0·75 additional choline as choline chloride (CHOLINE, n 8) and offered three times their individual energy requirement divided into three meals. At weeks −1 and 12, fasted blood was sampled and serum analysed for 130 metabolites via Di-MS and fifty-one metabolites via NMR spectroscopy. Changes in fasted metabolites were assessed using a repeated-measures GLIMMIX procedure with time and group as fixed effects, and time as a repeated measure. Metabolites of one-carbon metabolism and lipids increased, and medium-chain acyl carnitines decreased from week −1 to 12 for CHOLINE (P < 0·05), but not CONTROL (P > 0·05). Increases in amino acid, biogenic amine and organic compound concentrations were observed in both groups (P < 0·05). The results suggest impacts of dietary choline at greater intakes than currently recommended on one-carbon metabolism and fatty acid oxidation, and these may promote healthy growth in post-gonadectomy kittens.

Integrated omics analysis reveals differences in gut microbiota and gut-host metabolite profiles between obese and lean chickens

Abdominal fat is the major adipose tissue in chickens. In chicken, the deposition of abdominal fat affects meat yield and quality. Previous reports suggest that gut microbiota composition and function are associated with lipid metabolism. In this study, we used comparative metagenomics and metabolomics analysis to determine the gut microbiota and gut-host metabolite profiles in Shouguang (SG; a Chinese chicken breed with low-fat deposition) and Luqin (LQ; a fatty-type chicken breed with a fast growth rate) chickens. The results showed that LQ chickens had higher body weight, eviscerated yield, abdominal fat yield, abdominal fat ratio, and triglyceride (TG) content in the breast muscle than SG chickens. Untargeted metabolomics analyses showed a total of 11 liver metabolites, 19 plasma metabolites, and 30 cecal metabolites differentially enriched in LQ and SG chickens based on variable importance in the projection (VIP) ≥ 1 and P ≤ 0.05. These metabolites are involved in lipid and amino acid metabolism. The relative abundance of bacteria in the microbiota differed significantly between the 2 chicken breeds. The functional prediction of microbiota abundant in LQ chickens was starch and lactose degradation. Erysipelatoclostridium was abundant in LQ chickens and significantly positively correlated to palmitoyl ethanolamide (PEA), a key regulator of lipid metabolism. Our findings revealed differences in liver and plasma metabolites between chicken breeds with different adipose deposition capacities. Long-chain acylcarnitines might be important markers of adipose deposition differences in chickens. The cecum's microbial communities and metabolome profiles significantly differed between LQ and SG chickens. However, the relationship between cecal microbiota and their metabolites and liver and plasma metabolites is not thoroughly understood. Future research will focus on relating tissue metabolite changes to intestinal microbiota and their effects on body fat deposition.

Dose-response relationship between dietary choline and serum lipid profile, energy expenditure and respiratory quotient in overweight adult cats fed at maintenance energy requirements

Choline is an essential nutrient linked to hepatic lipid metabolism in many animal species, including cats. The current study investigated the serum lipid profiles, serum liver enzymes, respiratory quotients and energy expenditures of overweight cats fed maintenance diets, in response to graded doses of supplemental dietary choline. Overweight (body condition score [BCS]:≥6/9) adult male neutered cats (n=14) were supplemented with five choline chloride doses for three-week periods, in a 5 x 5 Latin square design. Doses were based on individual body weight (BW) and the daily recommended allowance (RA) for choline (63mg/kg BW 0.67) according to the National Research Council. Doses were: control (no additional choline: 1.2 x RA, 77 mg/kg BW 0.67), 2 x RA (126mg/kg BW 0.67), 4 x RA (252mg/kg BW 0.67), 6 x RA (378mg/kg BW 0.67), and 8 x RA (504mg/kg BW 0.67). Choline was top-dressed over the commercial extruded cat food (3620mg choline/kg diet), fed once a day at maintenance energy requirements (130kcal/kgBW 0.4). Body weight and BCS were assessed weekly. Fasted blood samples were taken and indirect calorimetry was performed at the end of each three-week period. Serum was analyzed for cholesterol, high-density lipoprotein cholesterol (HDL-C), triglycerides, non-esterified fatty acids, glucose, creatinine, blood urea nitrogen (BUN), alkaline phosphatase (ALP) and alanine aminotransferase. Very low-density lipoprotein cholesterol (VLDL) and low-density lipoprotein cholesterol were calculated. Data was analyzed via SAS using proc GLIMMIX, with group and period as the random effects, and treatment as the fixed effect. Statistical significance was considered at P < 0.05. Body weight and BCS did not change (P > 0.05). Serum cholesterol, HDL-C, triglycerides, and VLDL increased with 6 x RA (P < 0.05). Serum ALP decreased with 8 x RA (P = 0.004). Choline at 4 x and 6 x RA decreased serum BUN (P = 0.006). Fed or fasted respiratory quotient and energy expenditure did not differ among dietary choline doses (P > 0.05). These results suggest that dietary choline supplementation at 6 x RA may increase hepatic fat mobilization through increased lipoprotein transport, and beneficially support hepatic health in overweight cats. Future studies that combine these results with existing knowledge of feline weight loss and hepatic lipidosis are warranted.

Dietary choline in gonadectomized kittens improved food intake and body composition but not satiety, serum lipids, or energy expenditure

Gonadectomy is a major risk factor for feline obesity. The lipotropic effects of choline have demonstrated benefits for growth and carcass composition in livestock. The consumption of supplemental choline on body weight (BW), body composition, lipid metabolism, energy expenditure (EE), and serum satiety hormones were evaluated in 15 gonadectomized male kittens. Kittens were offered a base diet formulated for growth (3310mg choline/kg dry matter [DM]) to daily energy requirements (DER) over an 11-week acclimation. Post-gonadectomy, kittens were assigned to a base diet (CONTROL, n = 7) or choline group (base diet with additional choline at 300mg/kg BW^0.75 as a top dress) (CHOLINE, n = 8). For 12-weeks post-neuter, kittens were offered three times their DER over three meals to mimic ad libitum feeding. At week -1 and 12, body composition was assessed using dual energy x-ray absorptiometry (DXA), 24-hour indirect calorimetry was performed for EE and respiratory quotients (RQ), and fasted serum samples were analyzed for lipid compounds and satiety hormones. Daily food intake (FI) and weekly BW were measured. Data was analyzed as a repeated measures of variance (ANCOVA) using the GLIMMIX procedure with time and group as fixed effects. CHOLINE had lower mean daily FI and lower rates of BW accretion (P<0.05) in contrast to CONTROL. All absolute body composition data increased over time for both groups, with lower increases in total tissue mass (P = 0.031) and fat mass (P = 0.005) in CHOLINE. Serum satiety hormones and lipid compounds did not differ (P>0.05) between groups, but both groups experienced a decrease in low-density lipoproteins and increase in high-density lipoproteins (P<0.05). Primary substrate utilization showed lipid use when fasted and use of protein or mixed macronutrients in the fed state. Fed state EE decreased post-gonadectomy (P = 0.004), however, CHOLINE did not affect total EE or RQ. These results suggest that supplemental dietary choline reduces FI, BW, and fat mass and may help to reduce the propensity of weight gain and subsequent obesity in gonadectomized feline populations.