Age and body weight effects on glucose and insulin tolerance in colony cats maintained since weaning on high dietary carbohydrate

High dietary carbohydrate is suggested to promote development of diabetes mellitus in cats. Glucose tolerance, insulin sensitivity, and insulin secretion were assessed in young [0.8–2.3 (median = 1.1) years, n = 13] and mature [4.0–7.0 (median 5.8) years, n = 12] sexually intact females of a large (n ? 700) feline colony in which only dry‐type diets (35% metabolizable energy as carbohydrate) were fed from weaning. Insulin sensitivity was assessed from the ‘late‐phase’ (60–120 min) plasma insulin response of intravenous glucose tolerance tests (IVGTTs) and from fractional change in glycaemia from baseline 15 min after an insulin bolus (0.1 U/kg, i.v.). Insulin secretion was assessed from the ‘early‐phase’ (0–15 min) plasma insulin response of IVGTTs. Compared to the young cats, the mature cats had greater body weights [2.3–3.8 (median = 2.9) vs. 3.0–6.3 (median = 4.0) kg, p < 0.01], greater late‐phase insulin responses (p < 0.05), lower insulin‐induced glycaemic changes (p = 0.06), lower early‐phase insulin responses (p < 0.05), and non‐significantly different rates of glucose disposal. The late‐phase insulin response was correlated with body weight and age (p < 0.05). When group assignments were balanced for body weight, the age‐group differences and correlations became non‐significant. The findings indicate that body weight gain is more likely than dry‐type diets to induce the pre‐diabetic conditions of insulin resistance and secretion dysfunction.     

Effects of dietary protein content on renal parameters in normal cats

This study evaluates the effect of dietary protein content on renal parameters in 23 healthy spayed female cats. The objective was to determine if cats eating diets high in protein will have higher serum urea nitrogen (UN) and creatinine values without a detectable change in kidney function, as assessed by urinalysis. A single random cross-over design was used. Cats were fed a standard maintenance diet for at least 1 month prior to the dietary trial. They were fed in two phases. For the first phase, cats were randomly assigned to receive either a high protein [HP=46% metabolizable energy (ME)] or low protein (LP=26% ME) diet. For the second phase, cats were fed whichever diet they were not fed during the phase I period. Blood and urine samples were collected at 2-week intervals for the duration of the study (10 weeks). UN, albumin, alanine aminotransferase and urine specific gravity were significantly higher, and creatinine and phosphorus were significantly lower (P<0.05) when cats were fed the HP diet as compared to when they were fed the LP diet, although none of the mean values were found to be outside of the corresponding reference interval. Dietary intake can result in clinically significant changes in UN and statistically significantly changes in several other biochemical analytes, although all analytes are likely to remain within normal reference intervals. Therefore, an accurate dietary history is necessary to help determine if renal parameters are being influenced by diet in a particular patient.     

Effects of dietary fermentable carbohydrates on energy metabolism in group-housed sows

The effect of dietary nonstarch polysaccharide (NSP) content on the metabolic rate in group-housed sows was studied. Twelve groups of six nonpregnant sows were each fed one of four experimental diets similar in composition except for the starch and NSP content. Exchanging sugar beet pulp silage (SBPS) for tapioca created the difference in starch and NSP ratio in the diet. On a DM basis, diets contained 0, 10, 20, or 30% SBPS. Sows were group-housed and fed at 1.30 times the assumed maintenance energy requirements. Nitrogen and energy balances were measured per group during a 7-d experimental period, which was preceded by a 33-d adaptation period. Both digestibility and metabolizability of energy decreased with increasing dietary SBPS content (P < 0.05). Heat production and energy retention were unaffected by the exchange of starch for NSP (P > 0.1). Based on energy retention data and apparent fecal digestibilities of crude protein, crude fat, starch, and NSP, the estimated net energy value of fermented NSP was 13.4 kJ/g. The present study shows that group-housed sows are capable of using energy from fermented NSP (i.e., NSP from SBPS) as efficiently as energy from digested starch (i.e., starch from tapioca).     

Effects of dietary fermentable carbohydrates on behavior and heat production in group-housed sows

The effects of dietary nonstarch polysaccharides (NSP) on behavior and heat production in group-housed sows were studied. Twelve groups of six nonpregnant sows were fed one of four experimental diets that were similar in composition except for starch and NSP contents. Exchanging sugar beet pulp silage (SBPS) for tapioca created the difference in dietary starch and NSP ratio. On a dry matter (DM) basis, diets contained 0, 10, 20, or 30% SBPS. Sows were group-housed. Intake of fermentable NSP (fNSP) for diets containing 0, 10, 20, or 30% SBPS averaged 7.06, 9.18, 11.61, and 13.73 g x kg(-0.75) d(-1), respectively. Sows were fed, once a day at 0800. Dry matter intake for diets containing 0, 10, 20, or 30% SBPS, averaged 38.05, 38.38, 38.53, and 38.35 g x kg(-075) x d(-1), respectively, and ME intake averaged 523, 518, 514, and 493 kJ x kg(-0.75) x d(-1), respectively. On average, sows spent 177 min/d on physical activity, of which 8.8% was spent on eating. Time spent in physical activity was affected by diet (P = 0.005). Sows fed 0 or 10% SBPS spent more time on physical activity than sows fed 20 or 30% SBPS (P = 0.002). Energy cost of physical activity averaged 464 kJ x kg(-0.75) x d(-1) (standard estimated mean of 31) and was similar for diets (P = 0.679). Total heat production (HP) and activity-related heat production (AHP) were affected by diet (P < 0.05). Sows tended to be quieter when fNSP intake increased (P = 0.063). The effect of fNSP intake on HP and AHP was not constant during the day. During the night period, fNSP intake did not affect HP and AHP (P > 0.10). During the day period, increased fNSP intake decreased HP (P = 0.006) and tended to decrease AHP (P = 0.062). During eating, increased fNSP intake increased HP (P = 0.012) and tended to increase AHP (P = 0.074). Despite similar DMI, sows fed 0 or 10% SBPS spent less time eating than sows fed 20 or 30% SBPS (P = 0.009). Feed consumption rate was higher (P = 0.003) in groups fed 0 or 10% SBPS than in groups fed 20 or 30% SBPS. Feed consumption rate decreased by 0.19 g DM x kg(-0.75). min(-1) (P = 0.003) for each gram of fNSP intake. The energy saving effect of physical activity on the NE value of fNSP from SBPS ranged between 2.3 and 3.7 kJ/g of fNSP intake. In conclusion, intake of fNSP from SBPS affected energy expenditure for physical activity (P = 0.063); however, this effect was not constant during the day.     

Evaluation of effects of dietary carbohydrate on formation of struvite crystals in urine and macromineral balance in clinically normal cats

OBJECTIVE: To evaluate effects of dietary carbohydrate on urine volume; struvite crystal formation; and calcium, phosphorus, and magnesium balance in clinically normal cats. ANIMALS: 21 healthy adult cats (15 sexually intact males and 6 sexually intact females). PROCEDURE: Diets containing no carbohydrate source (control diet), control plus starch, or control plus fiber were given in a 3 X 3 Latin-square design. The diets were available ad libitum in study 1 (n = 12) and given under restrictions in study 2 (9) to equalize daily intakes of crude protein among the 3 groups. Formation of struvite crystals and balance of calcium, phosphorus, and magnesium were measured. RESULTS: Urine volume was lower in the starch group and fiber group in study 1, whereas no differences were detected among the groups in study 2. Urinary pH and struvite activity product were higher in the starch group in both studies, and the fiber group also had higher struvite activity product in study 2. In both studies, urinary concentrations of HCl-insoluble sediment were higher in the starch group and fiber group. In the fiber group, a net loss of body calcium, phosphorus, and magnesium was detected in study 2. CONCLUSIONS AND CLINICAL RELEVANCE: Starch and fiber in diets potentially stimulate formation of struvite crystals. Hence, reducing dietary carbohydrate is desirable to prevent struvite urolith formation. In addition, a net loss of body calcium, phosphorus, and magnesium during feeding of the fiber diet suggests that dietary inclusion of insoluble fiber could increase macromineral requirements of cats.     

Effects of carnitine and taurine on fatty acid metabolism and lipid accumulation in the liver of cats during weight gain and weight loss

OBJECTIVE: To determine the effects of carnitine (Ca) or taurine (Ta) supplementation on prevention of lipid accumulation in the liver of cats. ANIMALS: 24 adult cats. PROCEDURE: Cats were fed a weight-gaining diet sufficient in n-6 polyunsaturated fatty acids (PUFAs), low in long-chain n-3 PUFAs (n-3 LPUFA), and containing corn gluten for 20 weeks. Cats gained at least 30% in body weight and were assigned to 4 weight-reduction diets (6 cats/diet) for 7 to 10 weeks (control diet, control plus Ca, control plus Ta, and control plus Ca and Ta). RESULTS: Hepatic lipids accumulated significantly during weight gain and weight loss but were not altered by Ca orTa after weight loss. Carnitine significantly increased n-3 and n-6 LPUFAs in hepatic triglycerides, decreased incorporation of 13C palmitate into very-low-density lipoprotein and hepatic triglycerides, and increased plasma ketone bodies. Carnitine also significantly increased weight loss but without altering the fat to lean body mass ratio. Taurine did not significantly affect any variables. Diets low in n-3 LPUFAs predisposed cats to hepatic lipidosis during weight gain, which was further exacerbated during weight loss. Mitochondrial numbers decreased during weight gain and weight loss but were not affected by treatment. Carnitine improved fatty acid oxidation and glucose utilization during weight loss without correcting hepatic lipidosis. CONCLUSIONS AND CLINICAL RELEVANCE: The primary mechanism leading to hepatic lipidosis in cats appears to be decreased fatty acid oxidation. Carnitine may improve fatty acid oxidation but will not ameliorate hepatic lipidosis in cats fed a diet low in n-3 fatty acids.     

Changes in body composition during weight loss in obese client-owned cats: loss of lean tissue mass correlates with overall percentage of weight lost

Obesity is one of the most common medical diseases in cats, but there remains little information on success of weight loss regimes in obese client-owned cats. No information currently exists on body composition changes during weight loss in clinical cases. Twelve obese client-owned cats undertook a weight loss programme incorporating a high-protein low fat diet. Body composition was quantified by dual-energy X-ray absorptiometry, before and after weight loss. Mean (+/-standard deviation) weight loss was 27+/-6.8% of starting weight, and mean rate of weight loss was 0.8+/-0.32% per week. Mean energy allocation during weight loss was 32+/-7.0 kcal/kg target weight. Mean composition of tissue lost was 86:13:1 (fat:lean:bone mineral). The proportion of lean tissue loss was positively associated with overall percentage of weight loss (simple linear regression, r(2)=44.2%, P=0.026). Conventional weight loss programmes produce safe weight loss, but lean tissue loss is an inevitable consequence in cats that lose significant proportions of their starting body weight.     

Effects of two different dietary fermentable carbohydrates on activity and heat production in group-housed growing pigs

The effects of two sources of dietary fiber (DF) on behavior and heat production (HP) in group-housed growing pigs were studied. Twenty clusters of 14 barrows (50 kg) were fed one of 10 diets. Diets differed mainly in type and content of fermentable DF (fDF) and in content of digestible starch. Five diets contained solvent-extracted coconut meal (SECM) and five diets contained soybean hulls (SBH) as the main fDF source. On an as-fed basis, pigs received 3.5, 13.2, 23.0, 32.7, or 42.4 g x kg(-0.75) x d(-1) of SECM or SBH. A total of 280 crossbred growing pigs were used, divided into clusters of 14 pigs each. Pigs were group-housed and fed at 2.5 times the assumed maintenance energy requirements. All clusters were fed similar amounts of NE, ileal-digestible protein and amino acids, vitamins, and minerals. Consequently, DMI differed among diets because NE content decreased with increasing DF content. After a 32-d preliminary period, HP was measured per cluster during a 7-d experimental period in environmentally controlled respiration chambers. Behavior of the pigs was recorded using time-lapse video recordings during two different days within the experimental period. Intake of digestible starch and fDF was different (P < 0.001) among diets, whereas intake of digestible CP was similar among diets. On average, pigs spent 153 min standing, 42 min sitting, 202 min lying on their chest, and 1,043 min lying on their flanks each day. Pigs fed SECM diets spent, on average, less time (P < 0.05) lying on their chest than pigs fed SBH diets. Total time spent on physical activity (i.e., standing plus sitting, 195 min/d) was not affected by diet. Total HP and resting HP were affected by diet and were on average lower (P < 0.01) for pigs fed SECM diets than for pigs fed SBH diets. Activity-related heat production (AHP) averaged 65 kJ x kg(-0.75) x d(-1) and was not affected by diet. There was a linear relationship (P < 0.001) between fDF intake and HP, but there was no relationship between fDF intake and AHP. During different parts of the day, fDF intake also affected HP. The saving effect of physical activity on the NE values of fDF from SECM and SBH were 0.56 and 0.84 kJ/g of fDF intake, respectively. Neither of these saving effects was significantly different from zero. We conclude that fDF from SECM and SBH did not affect energy expended on physical activity by growing pigs, and that the NE value of fDF from SECM and SBH was not affected by changes in physical activity.     

Effect of increased dietary protein and decreased dietary carbohydrate on performance and body composition in racing Greyhounds

OBJECTIVE: To determine effects of increased dietary protein and decreased dietary carbohydrate on hematologic variables, body composition, and racing performance in Greyhounds. ANIMALS: 8 adult Greyhounds. PROCEDURE: Dogs were fed a high-protein (HP; 37% metabolizable-energy [ME] protein, 33% ME fat, 30% ME carbohydrate) or moderate-protein (MP; 24% ME protein, 33% ME fat, 43% ME carbohydrate) extruded diet for 11 weeks. Dogs subsequently were fed the other diet for 11 weeks (crossover design). Dogs raced a distance of 500 m twice weekly. Rectal temperature, hematologic variables before and after racing, plasma volume, total body water, body weight, average weekly food intake, and race times were measured at the end of each diet period. RESULTS: When dogs were fed the MP diet, compared with the HP diet, values (mean +/- SD) differed significantly for race time (32.43 +/- 0.48 vs 32.61 +/- 0.50 seconds), body weight (32.8 +/- 2.5 vs 32.2 +/- 2.9 kg), Hct before (56 +/- 4 vs 54 +/- 6%) and after (67 +/- 3 vs 64 +/- 8%) racing, and glucose (131 +/- 16 vs 151 +/- 27 mg/dl) and triglyceride (128 +/- 17 vs 104 +/- 28 mg/dl) concentrations after racing. CONCLUSIONS AND CLINICAL RELEVANCE: Greyhounds were 0.18 seconds slower (equivalent to 0.08 m/s or 2.6 m) over a distance of 500 m when fed a diet with increased protein and decreased carbohydrate. Improved performance attributed to feeding meat to racing Greyhounds apparently is not attributable to increased dietary protein and decreased dietary carbohydrate.     

Glycaemic and insulinaemic responses to feeding hay with different non-structural carbohydrate content in control and polysaccharide storage myopathy-affected horses

The aim of this study was to determine whether the glycaemic/insulinaemic responses to hay with non-structural carbohydrate (NSC, soluble carbohydrate) of 17% (HC), 10% (MC) or 4% (LC) differs in control horses and whether these responses differ between control and horses with polysaccharide storage myopathy (PSSM). Five clinically normal control horses and seven PSSM horses, all unfit and of Quarter Horse breeding (age 9.4 ± 3.4 years, body condition score range: 4.5-6). A crossover design compared the HC and LC hay, with horses randomly assigned to hay type for 5 days, and all horses fed the MC hay during washout, after which the diets were switched. Horses were fed 1.5% BW (as fed) divided into 2 feeding per day, no grain. On morning of the fifth day of each block (seventh day for washout), horses were given 0.5% BW in hay, blood was drawn before and every 30 min for 5 h after feeding, and the rate of intake was measured. Whole blood glucose and plasma insulin were measured. The intake rate was significantly higher for HC. In control horses, the insulin area under the curve (6891.7 ± 3524.2 HC vs. 1185.4 ± 530.2 LC) was significantly higher than LC. Polysaccharide storage myopathy horses had significantly higher glycaemic and insulinaemic responses to HC vs. LC, however; the magnitude of insulin response was lower and glucose response higher in PSSM vs. control horses. Results suggest that insulin responses can differ significantly with the NSC content of hay. Feeding hay with 17% NSC produces elevations in insulin that could be detrimental for PSSM horses.     

Care and use of feeding tubes in dogs and cats

Feeding tubes are an accepted way of providing nutritional support for animals unable or unwilling to consume adequate calories on their own. This article provides information on the indications for the use of feeding tubes in small animals, the types of tubes available, and ways to initiate nutritional support once the tubes are in place. The pros and cons of the various tubes are discussed, as well as potential complications.     

Potassium depletion in cats: renal and dietary influences

Excessive urinary potassium loss was diagnosed in 7 cats with persistent hypokalemia and high serum creatinine concentrations. Renal tubular acidosis (proximal or distal) was not evident in the affected cats. Plasma aldosterone concentrations and plasma renin activities in affected cats were not significantly different from control values. Potassium depletion and hypokalemia were attributed to the combined effects of decreased dietary potassium intake and excessive urinary potassium losses. It was concluded that increased urinary potassium excretion may represent a basic response to renal dysfunction in cats. Data suggested that dietary potassium supplementation improved renal function in most cats in this study.     

Influence of dietary protein and carbohydrate sources on nitrogen metabolism and carbohydrate fermentation by ruminal microbes in continuous culture

Four diets containing 15% CP were formulated to study the effects of dietary carbohydrate and protein sources on N metabolism and carbohydrate fermentation by ruminal bacteria. Diets were supplied to eight dual-flow continuous culture fermenters during three experimental periods in a randomized complete block design. Six replications were obtained for each diet. Treatments were arranged as a 2 X 2 factorial with two carbohydrate and two protein sources. Carbohydrate sources were corn and barley and protein sources were soybean meal (SBM) and fish meal (FM). Approximately 40% of the dietary CP was derived from SBM or FM and corn or barley provided 39% of dietary DM. All diets contained 15% grass hay, 20% wheat straw, and 10.1 to 15.3% solka floc (DM basis). Interactions (P less than .05) were observed between dietary carbohydrate and protein sources, resulting in a depression of VFA production (moles/day) and digestion (percentage) of ADF and cellulose when the corn-FM diet was fed. True OM digestion (percentage) was higher (P less than .05) for SBM than for FM diets and for corn than for barley diets. Although dietary CP degradation (percentage) was higher (P less than .05) for SBM than for FM diets, non-NH3 N in the effluent (grams/day) was not different among diets due to a greater (P less than .05) bacterial N flow for SBM than for FM diets. Despite the lower amino acid (AA) intake (P less than .05) for corn than for barley diets and also for FM than for SBM diets, flows (grams/day) of total AA, essential AA (EAA), and nonessential AA (NEAA) were similar (P greater than .05) among diets. However, greater (P less than .05) total AA, EAA, and NEAA flows (percentage of AA intake) were found for corn than for barley diets and for FM than for SBM diets. It is concluded, therefore, that ruminal escape protein derived from corn or FM has a significant effect on manipulating AA leaving the ruminal fermentation.