How can we predict the energy content of wet diets?
General nutrition
This study compared metabolisable energy of 30 canned canine diets calculated using predictive equations versus determined by digestibility trials. Metabolisable energy (ME) of pet foods can be determined by animal trials or predicted using published equations. To date, the most commonly used equation is the modified Atwater equation (3.5 kcal/g of protein and carbohydrates; 8.5 kcal/g of fat) proposed by the National Research Council (NRC) in 1985. This equation is still recommended by the Association of American Feed Control Officials (AAFCO). In 2006, however, the NRC has recommended newer predictive equations of ME based on digestible energy estimated as a function of total dietary fibre (based on TDF* content). The objective of the study was to compare ME of canine canned diets determined by those equations versus ME determined by digestibility trials, which are the gold standard.
Intro A strong commitment to support research The 14th AAVN Clinical Nutrition and Research Symposium took place on June 4th 2014, in Nashville, Tennessee (USA). Royal Canin was proud to support this annual meeting of the American Academy of Veterinary Nutrition, gathering about 120 world-class academics and researchers specialised in veterinary nutrition. This event was organised the day before the 2014 ACVIM forum, at which two research projects supported by Royal Canin were presented and at which Dr Natalie Finch, whose PhD on the prediction of the development of azotaemia in geriatric cats, carried out at the Royal Veterinary College, London (supported by Royal Canin), was awarded the 2014 IRIS Award, the most prestigious award for young scientists in the field of small animal nephrology. Indeed, another way to support research is to encourage young scientists who will build tomorrow’s science. Congratulations to Frank Looringh van Beeck (Utrecht University, Netherlands), a PhD student sponsored by Royal Canin who successfully defended his PhD thesis “Host and environmental contribution to atopic dermatitis in dogs”. This work has already given rise to the publication of 3 original articles in peer-reviewed journals.
The mean (±SD) measured ME of diets was 1027±242 kcal/kg as fed (range: 535-1703 kcal/kg). High correlations were found between ME measured and predicted by modified Atwater (R²=0.954) or NRC 2006 (R²=0.937) equations. Mean error of prediction was slightly higher for modified Atwater (82±50 kcal/kg, 8.0%) than for NRC 2006 (59±34 kcal/kg, 6.1%). The modified Atwater equation gave a general underestimation of ME (-8%) whereas NRC 2006 was very close to the measured ME, especially for diets with an energy density ≥900 kcal/kg.
Marie-anne Hours (Scientific Support- R&D)
Modified Atwater and NRC 2006 (TDF) equations can be used to predict Metabolisable Energy content of canned canine diets whilst accuracy remains slightly higher with the NRC 2006 equation.
NRC2006 Modified Atwater Reference curve
Urinary
*TDF= total dietary fibre
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NRC2006 equation y = 0,9748x + 57,686 R2 = 0,9369
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High salt diet: no threat for healthy older cats!
This long-term prospective, blinded, controlled study assessed the effect of a high salt diet on renal1 and cardiovascular2 function of 20 healthy aged cats.
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Modified Atwater equation y = 0,9028x + 19,737 R2 = 0,9542
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ME Measured (kcal/kg) Weber M, Leverger L, Biourge V. Modified Atwater and NRC 2006 equations can predict metabolisable energy in canned canine diet. Proc. of the WINSS 2013; October 1-4, Portland,
Just out of the press! Available online articles:
1. Season has an impact on food intake in cats (see News from Reseach #6) Serisier S, Feugier A, Delmotte S, Biourge V, German AJ. Seasonal variation in the voluntary food intake of domesticated cats (Felis catus). PLoS One. 2014 Apr 23;9(4):e96071. Free online access 2. Dietary intake of copper: worth being closely monitored in Labradors! (See News from Research #8) Fieten H, Biourge VC, Watson AL, Leegwater PA, van den Ingh TS, Rothuizen J. Nutritional management of inherited copperassociated hepatitis in the Labrador retriever. Vet J. 2014 Mar;199(3):429-33
© ROYAL CANIN SAS 2014. All Rights Reserved - Credits: Duhayer, Labat, Labat/Rouquette
ME predicted by Modified atwater or NRC2006 Tdf (kcal/kg)
Measured vs. Predicted ME using modified Atwater or NRC2006 (TDF)
#12 - July 2014
Digestibility trials of 30 canned canine diets were run in 6 female dogs of small breeds (Bichon, Miniature Schnauzer and Westie, 1-5 years of age). After a 9-day adaptation period, all faeces were collected over a 5-day period. For each dietary trial, proximate analysis, gross energy of the diet and the faeces as well as digestibility data on 6 dogs were available. ME was predicted by modified Atwater and NRC 2006 with TDF equation using measured proximate values; these calculated values were compared with the experimentally determined ME by linear regression analysis.
High sodium dry diets are available for cats to increase water intake and urine volume, as part of the prevention or treatment of urinary stone, and potential adverse effects of high dietary salt intake on kidney and cardiac functions have been suggested in older cats. The objective of this blinded study was to compare the effects of two extruded diets, similar in all but their salt contents, on renal and cardiovascular variables in aged cats. Twenty healthy neutered Domestic Shorthair colony cats (10.4 ± 2.4 years) were randomly allocated into two matched groups. One group was fed a high sodium diet (1.3% Na as fed; 3.1 g/Mcal) and the other one a control diet (0.35% Na as fed; 1.0 g/Mcal); all cats were regularly monitored over 2 years. Clinical examination, glomerular filtration rate (GFR), blood pressure measurement, kidney and cardiac ultrasonography (including Tissue Doppler examination), as well as kidney and blood tests were repeatedly performed over the 24 months following diet implementation. The protocol was reviewed and approved by both the suitable local and Royal Canin ethics committees. Results showed that GFR and other routine clinical pathological variables in healthy aged cats were not affected by dietary salt content. The only variables affected by salt intake were plasma aldosterone and sodium/creatinine ratio, respectively higher and lower in the control group. As regards to cardiac function, blood pressure, heart rate, cardiac morphology and myocardial functions remained unaffected by sodium intake. Out of the 33 tested imaging
variables, only one differed between the 2 groups (the TDI E/A ratio* measured in the subendocardial segment, statistically lower in the high salt diet group, at 12 months only). High dietary salt intake over 24 months had no effects on renal or cardiac function, blood pressure, and other health parameters in older cats. These findings agree with all but one shorter study on the effect of dietary salt on renal and cardiac function in cats.
Nutrient composition of the 2 diets Nutrient
High Salt Diet**
Control Diet
Moisture
13.6 ± 0.8
16.0 ± 1.5
Protein
87.0 ± 3.8
84.0 ± 2.8
Fat
39.2 ± 1.8
39.5 ± 1.5
Minerals
21.1 ± 1.3
15.3 ± 0.3
Total dietary fiber
16.1 ± 2.0
18.0 ± 2.3
Sodium
3.1 ± 0.1
1.0 ± 0.1
Chloride
5.5 ± 0.3
2.2 ± 0.3
3976 ± 55
4000 ± 32
(g/Mcal ME)
ME
(kcal/kg, NRC 2006)
**Veterinary Diet Urinary High Dilution Feline, Royal Canin *TDI= Tissue Doppler Imaging; E/A ratio = ratio of the early (E) to late (A) ventricular filling velocities. 1Reynolds BS, Chetboul V, Nguyen P, Testault I, Concordet D, Sampedrano CC, Elliott J, Trehiou-Sechi E, Abadie J, Biourge V, Lefebvre HP. Effects of dietary salt intake on renal function: a 2-year study in healthy aged cats. J Vet Intern Med 2013, 27 :507-15 2Chetboul V, Reynolds BS, Trehiou-Sechi E, Nguyen P, Concordet D, Sampedrano CC, Testault I, Elliot J, Abadie J, Biourge V, Lefebvre HP. Cardiovascular effects of dietary salt intake in aged healthy cats: a 2-year prospective randomized, blinded and controlled study. PLoS One. 2014 Jun 18;9(6):e97862. Free online access
Obesity-Satiety
Weight loss regimen: what does it cost?
This study compared the average costs of feeding an obese dog before weight loss and during a weight loss programme. Weight loss in obese dogs generally involves feeding a purposeformulated diet over a long period of time, but the cost of the food may deter some owners from starting a weight management programme. This study calculated the cost of feeding an obese dog during weight loss, and compared this to food costs prior to weight loss. Twenty-two dogs referred to the Royal Canin Weight Management Clinic (Liverpool, UK) were included in the study (median age 5.9 years). To be eligible, dogs had to have completed a weight loss programme, successfully reaching their target weight, and accurate dietary information prior to weight loss had to be available. All dogs underwent a weight loss programme consisting of dietary energy restriction and increased activity. One of three Royal Canin weight management diets was used: Satiety Support dry (n=13), Obesity Management dry (n=8), or a combination of Obesity Management dry and moist (n=1). During the whole programme, owners maintained a diary in which they recorded the diet ration fed. To ensure accuracy of portion sizes, owners weighed all food portions with electronic kitchen scales. The average daily cost of the diet fed before weight loss was calculated, including the main meal and extras (treats, table scraps, etc…) and was compared to the cost of feeding during weight loss. During the weight loss programme, none of the dogs received additional food apart from their weight loss diet.
Costs were based upon the cheapest prices identified by an internet search (Google 2012); for human items, the website of a UK supermarket was used (Tesco Online 2012). Median weight loss duration was 291 days (89 to 824 days), and median weight loss during this time was 26% (10-44%). Median energy intake during weight loss was 60 kcal/kg0.75/day (47 to 74 kcal/ kg0.75/day). Median daily food cost prior to weight loss was £0.52/ day (£0.24 to £3.31), and was not significantly different from median daily food cost during weight loss (£0.90, from £0.26 to £1.36). This remained the case when dogs on prescription diets prior to weight management were excluded. This study demonstrated that, on average, weight management is cost neutral. This information is of great interest to help veterinarians to reassure owners before starting a weight loss programme. German AJ, Luxmore J, Holden S, Morris P, Biourge V. Feeding fat pets: what does it cost? Proc. of BSAVA Congress, 4-7 April 2013, Birmingham, UK
Main meal before weight loss
n = 8 Maintenance “light” diet n = 4 Home cooked diet n = 1 Therapeutic weight loss diet n = 7 Other therapeutic diet n = 2 Maintenance diet
Hairball
Dietary fiber: a tool to limit hairball formation
The effect of dietary fibre on faecal hair excretion was assessed in 21 healthy adult short and long-haired cats. Hairballs result from hair ingestion during grooming and are a common cause for veterinary consultation in cats. Vomiting is the most frequent clinical sign but hairballs can also result in severe consequences such as intestinal obstruction. The objective of this study was to assess the influence of dietary fibre on faecal hair excretion in short and long-haired cats. Twenty-one healthy adult cats were divided into three collective panels: • A long-haired panel (LH cats, n=7) • A short-haired panel (SH cats, n=7) •A control shedding panel, including short (n=3) and long-haired cats (n=4).
The assessment of hair shedding showed a regular quantity of hair recovered over the weeks. Moreover, the quantity of hair brushed from all cats did not significantly vary between weeks (p>0.05). These results indicated that the study did not take place during shedding season. Compared to the control diet, diet 15 significantly increased (p<0.001) faecal hair excretion by 113% in the LH panel. No influence of diet was observed in SH cats, however. This could be explained by the low quantity of hair ingested by these animals outside the shedding season. This study demonstrated that dry diets enriched with dietary fibre and psyllium can significantly increase faecal hair excretion in long-haired cats, within only 14 days. Weber M, Sams L, Soulard Y, Feugier A Biourge V. Influence of the dietary fiber level on fecal hair excretion after 14 days in short and long-haired cats. Proc of AAVN Clinical Nutrition & Research Symposium, June 4, 2014, Nashville, Tennessee (USA).
Two identical dry diets were specially manufactured for the study, varying only in their total dietary fibre content (TDF): Diet 6 (control diet, TDF 6.0% as fed, no psyllium), and Diet 15 (TDF 14.9% as fed, including psyllium husks). After 3 days of a purge (SavorialTM, MSD, France) to eliminate hair in the digestive tract, all cats of the LH and SH panels were successively fed the control low-fibre diet and the high fibre diet (Diet15). Each diet was offered to cats for 14 days. Faecal hair excretion was quantified daily. In parallel, shedding was assessed 3 times a week throughout the study period, with standardised brushing of shedding control cats. Data were analysed using a generalised linear model procedure.
Faecal hair excretion (mg/day)
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+ 113%
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n = 17 Vegetables n = 10 Meat n = 1 Bread n = 3 Chocolate n = 1 Dog treats
Additional food before weight loss
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Mean faecal excretion with control diet and test diet
*** : p<0.001