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Macronutrient intake of dogs, self-selecting diets varying in composition offered ad libitum



The diet of the domestic dog has changed significantly from that of its wolf ancestor, with to date only two studies having examined macronutrient self-selection in dogs. Whilst the first focused solely on protein intake, determining an intake of 30% metabolisable energy (ME), the second investigated dietary protein, fat and carbohydrate (PFC), indicating an intake ratio of 30:63:7% by energy. This study's aim was to further elucidate macronutrient intake by providing greater macronutrient range, energy content, and to investigate over a longer duration than previous studies. Fifteen adult dogs were given access to three wet diets providing 500% of daily ME, twice daily over 10 days. The diets were nutritionally complete and formulated using the same four ingredients in different proportions to supply high levels of protein (58% ME), fat (86% ME) or carbohydrate (54% ME). Overall fat and carbohydrate consumption significantly declined from 6,382 to 917 kcals per day (p < 0.001) and 553 to 214 kcals day⁻¹ (p < .01) respectively. Protein intake, however, remained constant over the study and ranged from 4,786 to 4,156 kcals day⁻¹. Such results impacted on percentage total energy intake, with fat decreasing from 68% to 52% (p < .001) and protein increasing from 29% to 44% (p < .01). Our findings suggest that dogs still possess a “feast or famine” mentality, wherein energy dense fat is prioritised over protein initially. With continued feeding over 10 days, a transition to a more balanced energy contribution from both macronutrients is evident. The study also shows that given the option, dogs do not select carbohydrate to be a significant portion of the diet. The health implications of such dietary selection are of interest.
J Anim Physiol Anim Nutr. 2017;1–8. 
DOI: 10.1111/jpn.12794
Macronutrient intake of dogs, self- selecting diets varying in
composition offered ad libitum
M. T. Roberts1,2 | E. N. Bermingham1| N. J. Cave2| W. Young1| C. M. McKenzie3|
D.G. Thomas2
1Food Nutrition & Health Team, Food &
Palmerston North, New Zealand
Sciences, Massey University, Palmerston
North, New Zealand
Sciences, Massey University, Palmerston
North, New Zealand.
Funding information
withto dateonlytwostudies having examinedmacronutrientself-selectionin dogs.
Whilstthefirstfocusedsolelyonprotein intake, determining an intake of 30% me-
tent, and to investigate over a longer duration than previous studies. Fifteen adult
dogswere given access to threewet diets providing 500% ofdaily ME, twice daily
over10days.The diets were nutritionally complete andformulatedusing the same
nificantly declined from 6,382 to 917kcals per day (p<0.001) and 553 to
214kcalsday−1(p<.01) respectively. Protein intake, however, remained constant
overthestudyandrangedfrom4,786to4,156kcalsday−1. Such results impacted on
percentagetotal energy intake, withfatdecreasingfrom68%to 52% (p<.001) and
option,dogs do not select carbohydrateto be a significantportionof the diet. The
health implications of such dietary selection are of interest.
Whilst archaeological records cannot determine whether domestic
dogsoriginated from a single wolfpopulationorarose from multiple
populations at different times (Frantz etal., 2016; Vilà etal., 1997),
dogs are the only largecarnivore to have been domesticated, most
suchwolfancestry,thedomesticdogisclassifiedasa carnivore,with
teeth adapted for grasping and tearing; however, they also possess
omnivoroustraits(Serpell,1995).The doghasarequirementforboth
©2017TheAuthors.Journal of Animal Physiology and Animal NutritionPublishedbyBlackwellVerlagGmbH.
The macronutrient composition of modern dog foods canvary
significantlydepending onthe format fed.This is largely due to the
kibbled diets typically contain 16%–38% protein, 6%–18% fat and
40%–60% carbohydrate (dry matter basis). However,wet/raw diets
typically containno or low levels (<10%) of carbohydratecombined
with higher levels of protein and fat (45% and 50% respectively).
popularfeedingoption,beingfedto over88%ofdogs(NewZealand
composition has yet to be determined, obesity and its many associated
conditions such as diabetes, cardiorespiratory disease and urinary dis-
ordersare an increasing health risk forcompanion animals (German,
2006). Indeed in the past 10years, approximately 30%–40% of pet
dogsareclassifiedasbeing overweight,whilstanadditional5%–20%
termed obese (Witzel etal., 2014).Although the establishment of a
health,itmayserveas astartingpointforfutureresearch,wherebya
specific dietary macronutrient composition could be assessed in refer-
The ability of animals to select a macronutrient ratio that optimises
fitness costs (such as lifespanand rate of reproduction) has to date
Behmer,& Raubenheimer,2004).Moreover,establishing the macro-
ence between what they want to consume, and what most commercial
diets are providing. Further questions may also be addressed as to
an attempt to reach an intuitive predetermined macronutrient profile
when provided with an inappropriate dietary composition.
Froma nutritional standpoint, whilst feeding biologically appro-
priate diets to pet dogs has not currently been shownto provide
any health benefits, raw meat diets have been demonstrated to be
highlydigestible,resultinginlowfaecalvolumeand desirablefaecal
diets that differ substantially from what their ancestors consumed.
that the dietary composition of wild wolves showed the selected
To date, only two studies have examined dietary macronutrient
selectioninthedog.Whilstthe firststudy appeared to demonstrate
apreferenceforproteinovercarbohydrates(consuming30% protein
by energy), the impact of fat was not fully determined (Romsos &
ingan overallprotein/fat/carbohydrateratio(P:F:C) ofapproximately
(Hewson-Hughesetal.,2012). However,the restriction of dailytotal
foodintakeincertainexperimentalstages (e.g.,100%ofMERforthe
by which the animals could fully select the provided diets. In addition,
the structuring ofdifferent feeding phases and diet composition se-
ability to self-select a macronutrient ratio, theywill consume 30%
oftheir maintenance energy requirements from protein.However,a
numberofcommercialwetdiets containin excessofthisvalue,with
this factor. Therefore, the hypothesis of the study was that dogs
protein. The aim of this study was, therefore, to establish the self-
ofdiets, each specifically higherinenergysourced fromproteinand
macronutrient capabilities ofthe domestic dog to be examined in a
deeper manner than has previously been conducted. Subsequently
ourfindingswill eitherreinforceorchallengethoseofthepreviously
conductedstudies,withthe potentialtohighlight thatadogmaystill
2.1 | Ethics
Committee (MUAEC 15/75), before commencing the experiment.
The dogs were housed at Massey University Canine Nutrition Unit
(Palmerston North, New Zealand), in accordance with the Animal
2.2 | Animals
Fifteen Harrier hound dogs (five male and 10 female) were used
throughout the study, comprising of four neutered and one entire
deemedhealthy based on a physical examination. The mean ageof
4in grass paddocksmeasuring700m2 for 8hraday. Overnight the
2.3 | Diets
was formulated to meet AAFCO Dog Food Nutrient Profiles for adult
maintenance(AssociationofAmerican FeedControlOfficials,2015).All
diets consisted of the same four ingredients at different inclusion lev-
els, namely maize, lamb loin fat, green tripe and venison mechanically
A 5-dayperiod was used to adapt the dogs onto the test diets,
HPand HC diets,whilst concurrently decreasingtheirexistingcom-
by20%. Therefore,by the last day of the adaption period, the dogs
at which point they were deemed to have been fully transitioned.
ingofthe dogsbeingoffered250% oftheir dailyME requirementof
2.4 | Experimental protocol
Thedogswereweighedatthestart(day1),middle(day 5) and end
(day10)oftheexperimentalperiod(Table2).In orderto assessself-
selected macronutrient consumption, three large plastic bowls each
containing250%ofthe dailyenergyrequirement oftheHF, HCand
for 10days (Figure1). The position of each bowl was interchanged
at each feeding time to prevent positional bias. A number of feed-
eachfeeding period andafterwardsvia the use ofavideo recording
observations involved which diets were approached first, which
diets consisted of any consumption first and which diets were com-
achieved. This was defined as the point whereby the animal lost inter-
est in any of the diets.
2.5 | Calculations
Protein, fat and carbohydrate energy intakes were determined by
applying modified Atwater factors (protein/carb 3.5Kcalg−1 fat
8.5Kcalg−1) (National Research Council, 2006). As these data were
bysubtracting thetotalof eachdietprovided toeachdog from that
remaining after each dietary exposure. Additionally macronutrient
ratiowas determined as the overall percentageenergy contribution
thateachmacronutrientmadetoeach diet.Therefore,byaddingthe
macronutrient could be established.
2.6 | Statistical analysis
Separate analyses were conducted for each of the response variables
forseparate slopes and intercepts to be fitted for each dog.As the
experimentinvolved dogsofboth sexes(5maleand10 female), the
nificant differences were found, so these factors were not included in
2016).Alldatawerereportedas interceptand slopewith associated
Fisher’sexacttestwas used to compare the proportionsoffirst
on diet avoidance, with diet avoidance as the binary response variable
Bodyweight was analysed with a repeated measurements lin-
earmixed model (REML) with the factormeasurementday (levels1,
TABLE1 Macronutrientprofilesofhighprotein(PFC
Nutrient DM (g/100 g) HF HC HP
Moisture(asfed) 41.2 26.2 73.0
Protein 23.9 19.3 71.2
Fat(etherextract) 66.4 12.4 21.2
Ash 7.5 4.8 5.5
Carbohydrate 0.9 59.3 0.9
Crudefibre 1.3 4.2 1.2
ME(Kcalkg−1)a6,512 3,805 4,325
DM,DryMatter; HP,HighProtein;HF,High fat;HC,HighCarbohydrate;
aCalculated from modified Atwater factors (National Research Council,
TABLE2 Meanbodyweightofdogs(n=15)offeredhighprotein
Day 1 Day 5 Day 10 p- value
Mean 25.9c27.0b27.5a<.001
SEM 0.72 0.77 0.77
SEM, Standard error of mean.
FIGURE1 Experimentaldesigninvolvingdogsofferedhigh
10 days
5and 10). Analysiswasconducted using GenStat18thedition(VSN
International,2016). Results are presented as means and associated
3.1 | Bodyweight
Bodyweightincreased significantly (p<.001) over the 10-day study
was 25.9kg±0.72 SEM which increased to 27.5kg±0.77 SEM on
day 10.
3.2 | Energy intake
Over the course of the study, the dogs reduced (p<.001; Table3)
3.3 | Feeding dynamics
Throughout the duration of the experiment, the percentage of
dogswhich first approached and first consumed a diet wasdeter-
thediet firstwas47%(±3.7 SEM)andfirstconsuming it64%(±6.0
SEM)(p<.001),forcarbohydrate24%(±3.0 SEM) first approached
thediet, with 4% (±1.9SEM)first consuming it (p<.001). Thehigh
fatdietdisplayednosignificantdifferencesbetweenthose firstap-
proached 29% (± 3.5 SEM) and first consumption 30% (±5.5 SEM)
FIGURE2 Overthe10-dayperiod,thepercentageofenergy
Mean % of energy consumed
FIGURE3 Percentageofhighprotein(P:F:C57:42:1%byenergy),
High protein High fatHigh carb
1st diet approached
1st diet consumed
FIGURE4 Percentageofhighprotein(PFC57:42:1%),highfat
High proteinHigh fa
igh carbohydrate
FIGURE5 Meanmacronutrientdailyconsumption(kcalsday−1)
declinedoverthestudy(p < .01 and p<.001respectively).
Kcals per day
Fat Protein Carbohydrate
of the carbohydrate diet being completely avoided, 20% (±2.3 SE)
of the fat diet and 3% (±1.0 SE) of the protein diet (Figure4). No
changesin this behaviour were observedover the duration of the
3.4 | Kcals per day of each macronutrient consumed
Over the course of the study, the daily consumption of carbohydrate
reduced(p<.01; Figure5) from 554 on day 1 to214kcalsday−1 on
day10(kcals=284.09(±64.12 SE)–26.04(±8.33SE)xDay (Table3).
Thekcalsper day of fat consumed also reduced (p<.001; Figure5)
(±1,197.65 SE)–607.24 (±124.10 SE)xDay (Table3). Consumption
ofprotein remained constant over the study ranging from 4786on
3.5 | Macronutrient consumption and ratio
Protein intake (as a proportion of total ME) increased (p<.01;
Figure6)from29.4%MEonday 1to 44%ME(ME%=27.77(±3.17
SE)+1.60(±0.36SE)xDay; Table3)byday10.Fatintakedecreased
difference in carbohydrate intake was observed (Figure6) over the
The P:F ratio reflects these differences, increasing significantly
(p<.001)fromday1 to10ofthestudy(P:F=0.40(±0.07SE)+0.05
thedogsonday1, which gradually changed to 45:51:4% by day10
(see Figure6, raw data solid lines), driven by this increase (p<.01)
in protein intake (ME day−1) and decrease (p<.001) in fat intake
Using the fitted regression line of Protein%=27.8+1.6 Day,
Protein%intakeonDay5was calculatedtobe 35.8%,increasingto
Our study shows that when dogs are allowed to self-select from
diets varying in macronutrient composition, they will consume at
least30% of theirenergyfromprotein, thus inagreementwithour
thestudy was37%,the energy consumptionalteredover thedura-
TABLE3 Linearandquadraticresponsestoanalysisoftotalenergyconsumed,gramsofmacronutrientsconsumed,specificoverall
Response Model αSE β1SEM β2SE
TotalEnergyConsumed(unit) Linear 373.10*** 40.42 −23.97*** 3.28 –
Quadratic 419.10*** 31.8 −60.00*** 8.78 3.43*** 0.78
Proteinintake(%ofoverallME) Linear 27.77*** 3.17 1.60** 0.36 –
Fatintake(%ofoverallME) Linear 69.95*** 3.14 −1.81*** 0.37 –
Linear 2.28*** 0.62 0.21 0.27 –
Protein(kcalsday−1) Linear 4,856.21*** 921.20 −70.00 96.95 – –
Fat(kcalsday−1) Linear 6,989.38*** 1,197.65 −607.24*** 124.10 –
Carbohydrate(kcalsday−1) Linear 284.09*** 64.12 −26.04** 8.33 –
Protein:Fat Ratio Linear 0.40*** 0.07 0.05*** 0.01 –
α, Intercept; SE, Standard error; β1,CoefficientofLinearterm;β2,CoefficientofQuadraticterm.
**p < .01.
***p < .001.
FIGURE6 Meanself-selectedmacronutrienttotalenergy
% energy intake
Protein Fat Carbohydrate
44%by day 10.Thisincrease in proteinintakewas associated with
a decrease in fat consumption over the experiment, with the dogs
consuming68% on day1and 52% by day10.Thus, the protein:fat
proteinandfat intake altered significantly during the study, carbo-
hydrateconsumption remained steadyat3% throughout thestudy.
These changes in macronutrient selection by the dogs are illus-
tratedin Figures7a,b.Anutrition trianglewasutilised, to represent
a multidimensional assessment of dietary composition information
(Raubenheimer,2011). Collectively,thesechanges in macronutrient
intakeresultedinenergy consumptiondecreasingfrom of363%on
Based on raw data energy intake, the dogs selected an average
macronutrientP:F:C ratio of38:59:3%(byenergy) during the study.It
mustbe noted,however,thattheP:F:Cratio onday1(35:62:3byen-
ergy)wasdifferenttothat consumedon day10 (45:51:4% byenergy).
Thisdifferencewasdriven by the decreaseinfat energy consumption
(6,382–917kcalsday−1) ratherthan any drop in protein intake(4,786 
(Ishiokaetal., 2002).Asleptin serves asasignallingpathway between
The initial targeting of fat dense food sources has also been
demonstrated in the predatory beetle Agonum dorsale (Carabidae)
withthe first 2days involvingtargetinga diet rich in fatafterwhich
protein intake increased.Although this study involved determining
pattern. Our dogsalso targeted a high fat diet initially, with energy
evolutionary past, whereby limited prey availability would predispose
were maintained at a healthy body condition score, variations in how
a score relates tobody fat content can occur (Ishioka etal., 2005).
Further studies in dogs investigatingthe association between body
suchas leptin involved in influencing food intake would help better
the dogs in our study to thatdetermined by Hewson-Hughes etal.
differences,namelythelengthofthe studyperiod, thecalculationof
In Hewson-Hughes etal. (2012), the experienced phase was
7 days in duration, whereas in the present study, it was 10 days. In
thestudy period,itwas apparentthat majordifferencesintheP:F:C
selected occurred during the latter stages of the study, averaging
anaveragemacronutrientratioacrossthewholeofthe experimental
periodmayfailto interpret the true nutritional movementthe dogs
madeoverrelatively short testing periods (7–10days). Forexample,
the established average macronutrient ratio observed by Hewson-
Hughes etal. (2012) overa 7-dayperiod (30:63:7% by energy) was
apartforeach dayand examined indetail,do these keytimeframes
becomeobvious.Themacronutrientselection bythedogswithin our
intake(68%vs.52%byenergy)andincreasein protein(29%vs.44%
FIGURE7 (a,b)Macronutrienttotalenergyintakeofindividual
Secondlythe experimental structure oftheHewson-Hughesetal.
(2012) study involvedthree distinct phases, of differing duration and
toall threemealoptions simultaneouslyfor7days),learning (eight,3-
HP)for adayof eachperiod)andexperienced (thesameasthenaïve
phase). Thus, the potential exists whereby within the self-selective
stagemayalsohaveconfuseddogs alreadystartingto targeta macro-
nutrientintake,thatisbyconfiningeachtoa specificdietfor24hours
andrepeatingthe process eight times. Therefore,thecombination of
ashorterstudyperiod, and the inclusion ofa learningphase, limiting
RomsosandFerguson(1983)also addressedmacronutrientselec-
also in fat and carbohydrate. Whilst the results showed the animals se-
varyingfrom 20% to 42% MEwithin the test diets,could potentially
The self- selected macronutrient profile has also been reported for
the domestic cat (Felis catus)usinganapproachsimilartothatapplied
tothe domestic dog. Hewson-Hughes etal. (2011), establishedthat
macronutrient energyprofile (P:F:C) was 52:36:12 (% byenergy). In
additionthe study also suggests that cats havea carbohydrateceil-
ingof 300kJday−1, which constrains them to deficits in protein and
fat(relativetothe determined intaketarget)when restrictedto high
carbohydrate diets (Hewson-Hughes etal., 2011). Aswith the dog
rationof theprojectwas apparent.However,usinganother member
ofthefelidfamilythemink (Mustela vison), it was demonstrated that
bohydratefixedat15%)froma numberofcomplementaryfoods,the
etal., 2009). This ratiowas observed throughout the 11-day study,
with additionally when confined to diets that did not allow the desired
protein:fat ratio to be achieved, the closet possible to that previously
firstconsumeda givendiet was determined (Figure3), itwasclear
catingmost ofthe dogswhich approachedthediet first,consumed
approachedit first, with 64% then consuming some ofitfirst.This
the study,the percentage of times that each diet was approached
andconsumed remainedconsistent.Thishighlightedthat theinitial
decisionto consumeaspecific diet atthestart oftheinvestigation
HFand HPdiets(20%and 3% respectively)(Figure4).Collectively,
these feeding dynamics may indicate that therewas an olfactory
differencebetween the diets. As with the percentage of diets first
approached and consumed, the proportion of each diet completely
avoided were similar over the duration of the study. This would in-
dicatethe preferenceofdogstotarget oravoidspecific diets from
9 days.
Indeed whilst we did not attempt to ensure palatability of our
diets were consistent (e.g., with the use of a palatant), the same
key ingredientswere used in all the diets, just in different propor-
tions. Interestingly research conducted by Salaun, Le Paih, Roberti,
Niceron, and Blanchard (2016) foundthat whilst the application of
a palatability enhancerincreased food intake in domestic cats, they
werestill capable of macronutrient regulationwhenofferedpairs of
differingdiets. Moreover,a recent study has also indicated thatthe
domestic cat is able to detect and maintain a macronutrient prefer-
tein:fatratioof70:30(byenergy),evenwhenthe dietwas flavoured
erenceforgreentripe,ratherthanadesireforproteinper say.Asimilar
throughout the experiment (maize). Evidently carbohydrates played
aminimal roleinregard toselecteddietary compositioninthe dogs;
however, it is possible that this specific carbohydrate source was dis-
rice orbarley). Future studies could addressthese questions, where
protein, fat or carbohydrate sources. Similarly, moisture content was
notconsistentbetween diets in thecurrent study, with the HC diet
had any impact on the resulting macronutrient profile, but studies
have indicatedin cats that energy intake and food consumption re-
In conclusion, the study clearly demonstrated that over a ten- day
experiment, the test dogs selected a diet dominated by consump-
tionofenergy derived primarily from fat and protein,withcarbohy-
drateplaying a minimal role in contributing to overall energyintake.
However, only after the completion of much deeper investigations
into the selective capabilities and mechanisms influencing these di-
We thank the staff at the Massey University Canine Nutrition Unit
Natural,AgResearchCore Funding(A21247) andAgmardt (A15013).
M. T. Roberts
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Additional Supporting Informationmay be found online in the sup-
How to cite this article:RobertsMT,BerminghamEN,Cave
offered ad libitum. J Anim Physiol Anim Nutr. 2017;00:1–8.
... The KD macronutrient profile differs remarkably from the RMBD profile. In terms of percent dry matter, a KD usually consists of a "protein:fat:carbohydrate" (PFC) macronutrient ratio 16-38%:6-18%:40-60%, whereas the PFC ratio of RMBD is typically %45:50%:0-10% (17). ...
... A couple of studies looking at macronutrient preference among dogs served several food choices of varying macronutrient compositions ad libitum have indicated that several breeds of dogs are well-attuned to what they prefer and what their bodies require (17,118). In the first study, the authors observed that several breeds of dogs adjusted to a preferred PFC macronutrient composition of 30%:63%:7% ME over a 7-day period (118), and another study observed that Harrier hound dogs adjusted to a PFC macronutrient ratio of 44%:52%:4% ME (17). ...
... A couple of studies looking at macronutrient preference among dogs served several food choices of varying macronutrient compositions ad libitum have indicated that several breeds of dogs are well-attuned to what they prefer and what their bodies require (17,118). In the first study, the authors observed that several breeds of dogs adjusted to a preferred PFC macronutrient composition of 30%:63%:7% ME over a 7-day period (118), and another study observed that Harrier hound dogs adjusted to a PFC macronutrient ratio of 44%:52%:4% ME (17). The adequacy of diets for domesticated dogs, especially with regard to macronutrient composition, has been studied by comparing their diet with the diet of wolf (Canis lupus) populations (119). ...
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Background: While anecdotal evidence has long claimed that a raw meat–based diet (RMBD) improves the metabolic health of canines, no rigorous scientific study has clarified this issue. Canine atopic dermatitis (CAD) has also been linked to metabolic health, but its relation to diet remains poorly understood. This study investigates whether dietary choice is linked to metabolic health in healthy and CAD-diagnosed canines via targeted serum and urine metabolomic analysis of polar, non-ionic metabolites, as well as whether the underlying CAD condition modulates the response to nutritional intake. Materials and Methods: Serum metabolites of client-owned Staffordshire bull terriers, divided into CAD-diagnosed (n = 14) and healthy (n = 6) cohorts, were studied. Urine metabolites of a subset of the CAD-diagnosed canines (n = 8) were also studied. The canines were split into two cohorts based on diet. The first cohort were fed a commercially available high-fat, moderate-protein, low-carbohydrate RMBD (n = 11, CAD diagnosed n = 8, healthy n = 3). Those in the second cohort were fed a commercially available moderate-fat, moderate-protein, high-carbohydrate kibble diet (KD) (n = 9: CAD diagnosed n = 6, healthy n = 3). The diet intervention period lasted approximately 4.5 months (median 135 days). Statistical analyses of the serum profiles across all dogs (n = 20) and the urine profiles of the CAD-diagnosed subset (n = 8) were performed. Results and Discussion: The KD cohort was found to have higher concentrations of methionine than the RMBD cohort, both in serum (all dogs, p < 0.0001) and in urine (CAD-only cohort, p < 0.0002), as well as cystathionine and 4-pyridoxic acid. Methionine plays important roles in homocysteine metabolism, and elevated levels have been implicated in various pathologies. The CAD (n = 14) cohort dogs showed starker metabolic changes in response to diet regarding these pathways compared to the healthy (n = 6) cohort. However, there was no significant change in CAD severity as a result of either diet. Likely due to the higher meat content of the RMBD, higher concentrations of several carnitines and creatine were found in the RMBD cohort. Citrulline was found in higher concentrations in the KD cohort. Our findings provide insight into the relationship between diet and the serum and urine metabolite profiles of canines. They also suggest that neither diet significantly affected CAD severity.
... Carbohydrates (CHOs) are the most prevalent macronutrient found in dry extruded pet foods (~40-60% dry matter) [10,11]. The largest proportion of CHOs in pet food is provided by starch [12], which is made up of two glucose polymers: amylose and amylopectin [13]. ...
... Proximate analysis, total dietary fibre and energy contents as well as in vitro starch and free sugar contents of four commercial extruded dog foods containing different starch sources fed in a gastric emptying trial to11 clientowned Siberian Huskies. Treatment Whole grain: Chicken meal, oatmeal, whole brown rice, rye, barley, chicken fat (preserved with mixed tocopherols), salmon meal, lamb meal, natural chicken flavour, whole dried egg, rice bran, dried kelp, flaxseed, dicalcium phosphate, calcium carbonate, potassium chloride, choline chloride, l-lysine, sodium chloride. ...
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Gastric emptying rate (GER) may impact diabetes and obesity in humans and could provide a method to reduce canine weight gain. Starch, the most common source of carbohydrates (CHOs) in pet food, is classified as rapidly or slowly digestible, or resistant to digestion. This study investigated starch source effects in commercial extruded dog foods on the GER of 11 healthy adult Siberian Huskies (5.63±0.72 years; mean±SEM). Test diets were classified as traditional, grain-free, whole-grain, and vegan. Dogs received each diet once, a glucose control twice, and acetaminophen (Ac) as a marker for GER in a randomized, partially-replicated, 6x6 Latin square design. Pre- and post-prandial blood samples were collected at 16 timepoints from -15 to 480 minutes. Serum Ac concentrations were assessed via standard spectrophotometric assays and fitted with a mathematical model to estimate parameters of GER. Data was analyzed using a repeated measures ANOVA, followed by a Tukey-Kramer post-hoc test when significant (p<0.05). More total emptying (p= 0.0430) occurred at faster rate (p=0.0668) in dogs fed the grain-free diet, which contained the lowest total starch (34.03 ± 0.23%) and highest resistant starch (0.52 ± 0.007%). This research may benefit future diet formulations to reduce the prevalence of canine weight gain.
... In this context, balance captures the species-specific, individually variable, and temporally varying ratios of nutrients that optimize organismal 'fitness' (or another outcome), and balancing captures an evolving set of traits allowing organisms to achieve these ratios. While researchers use the term 'nutrient balancing' (Raubenheimer and Simpson 1997;Cohen 2001;Mayntz et al. 2009;Dussutour et al. 2010;Johnson et al. 2013;Chen et al. 2018), or nutrient 'selection' (Richter et al. 1938;Vivas et al. 2003;Roberts et al. 2018), the inclusion criteria for what constitutes this capacity, and what does not, are often left implicit. Instead, this capacity and its potential mechanisms of realization are mainly inferred from correlations between nutrient ratio variations and biological outcomes. ...
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While philosophers of science have marginally discussed concepts such as ‘nutrient’, ‘naturalness’, ‘food’, or the ‘molecularization’ of nutrition, they have yet to seriously engage with the nutrition sciences. In this paper, I offer one way to begin this engagement by investigating conceptual challenges facing the burgeoning field of nutritional ecology and the question of how organisms construct a ‘balanced’ diet. To provide clarity, I propose the distinction between nutrient balance as a property of foods or dietary patterns and nutrient balancing as an evolved capacity to regulate nutrient intake. This distinction raises conceptual and empirical issues, such as what properties constitute this capacity and whether they are the same in all organisms. Additionally, while scientists use the term ‘balancing’, its intension and extension need further clarification. Based on the literature, the properties of external nutrient detection, internal sensing of nutrient levels, and organismal regulation could provide a basic recipe for nutrient balancing. Next, using an evolutionary lens, I examine nutrient acquisition in some prokaryotes, slime molds, simple multicellular eukaryotes, and in the quirks of multicellular metabolism to raise questions about the origins and universality of balancing. Finally, I build on this explication of balance and balancing by considering how obesity and cancer might respectively elucidate problems of organismal nutrient imbalances versus disrupted cellular nutrient balancing.
... Carbohydrates (CHOs) are the most prevalent macro nutrient found in dry extruded pet foods (~40-60% dry matter) [8,9]. The largest proportion of CHOs in pet food is provided by starch [10], which is made up of two glucose polymers: amylose and amylopectin [11]. ...
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Gastric emptying rate (GER) may impact diabetes and obesity in humans and could provide a method to reduce canine weight gain. Starch, the most common source of carbohydrates (CHOs) in pet food, is classified as rapidly or slowly digestible, or resistant to digestion. This study investigated starch source effects in commercial extruded dog foods on the GER of 11 healthy adult Siberian Huskies. Test diets were classified as traditional, grain-free, whole-grain, and vegan. Dogs received each diet once, a glucose control twice, and acetaminophen (Ac) as a marker for GER in a randomized, partially replicated, 6 × 6 Latin square design. Pre- and post-prandial blood samples were collected at 16 timepoints from −15 to 480 min. Serum Ac concentrations were assessed via standard spectrophotometric assays and fitted with a mathematical model to estimate parameters of GER. Parameter values were subjected to ANOVA, with period and treatment as fixed effects and dog as a random effect. More total emptying (p = 0.074) occurred at a faster rate (p = 0.028) in dogs fed the grain-free diet, which contained the lowest total starch (34.03 ± 0.23%) and highest resistant starch (0.52 ± 0.007%). This research may benefit future diet formulations to reduce the prevalence of canine weight gain.
... En estudios realizados donde se mide el consumo voluntario de perros y gatos, informan de la proporción de la energía según el origen de esta, que permite optimizar el consumo de materia seca de forma voluntaria, en el caso de perros esta relación de proteína:grasa:carbohidratos es de 38:59:3 y en gatos es de 52:36:12 (Roberts et al., 2018), valores diferentes a los calculados para los alimentos para perros (26,43:32,33:41:24) y gatos (31,62:36,72:31,66) con registro activo en el país durante la evaluación, donde los alimentos evaluados, en promedio recargan el aporte energético en los alimentos en las fuentes de origen vegetal. ...
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Introducción: El análisis nutricional de alimentos comerciales ayuda a optimizar su uso y la nutrición de las mascotas, y no existen análisis recientes de este tipo para Costa Rica. Objetivo: Recomendar alimentos para mascotas de acuerdo al estado fisiológico, nivel de actividad y peso de perros y gatos en Costa Rica. Métodos: Los productos registrados en la Dirección de Alimentos para Animales del gobierno se analizaron para obtener información nutricional (2017) y los requisitos de los animales utilizando tres ecuaciones para gatos y nueve para perros. Resultados: De las recomendaciones de paquetes promedio, el 71% proporcionaría una nutrición insuficiente para los perros y el 63% una nutrición insuficiente para los gatos. Conclusiones: La mayoría de los productos alimenticios comerciales disponibles en Costa Rica recomiendan cantidades que son insuficientes para satisfacer las necesidades de muchos perros y gatos
... diets (Romsos and Ferguson, 1983;Hewson-Hughes et al, 2012;Roberts et al, 2017), raising the possibility that dogs fed modern commercial diets, low in protein, and high in carbohydrate and additives, might face physiological and metabolic challenges (Hill, 2010;Bosch et al, 2015). Furthermore, a wolf 's diet would be expected to provide a very different substrate for the intestinal microbiota, compared to both dry and moist commercial dog foods . ...
This article reviews the reasons for feeding domestic dogs and cats a diet based on raw meaty bones. Dogs, though able and willing to eat a wide variety of foods, exhibit numerous carnivorous traits, and are classified as carnivores. Dogs have been shown to prefer foods with nutrient profiles much closer to those of a wild wolf diet than those of kibbled diets, raising the possibility that dogs fed modern commercial diets, low in protein, and high in carbohydrate and additives, might face physiological and metabolic challenges. Cats are strict, obligate carnivores with characteristic dentition and a short digestive tract. A well-constructed raw food diet is high in protein, nutrient-rich, satiating, extremely palatable, and high in prebiotic ‘animal fibre’. Early domestic dogs were not ‘fed’ but allowed to forage for themselves like their wild ancestors. Today, most of our pets are fed on highly processed, dried diets, known commonly as ‘biscuit’ or ‘kibble’, barely recognisable from canine and feline ancestral diets. The intestinal microbiota has been found to vary significantly between raw-fed and non-raw-fed dogs. A species-appropriate, nutrient-rich diet, most closely resembling canine and feline ancestral diets, would seem a sensible option if our pets are to achieve optimal health. Feeding real, whole food consisting mainly of good quality raw meat on the bone, skin, offal, eggs and fish, is perhaps as close as we can come, in modern, Western society, to achieve this.
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Dogs are uniquely associated with human dispersal and bring transformational insight into the domestication process. Dingoes represent an intriguing case within canine evolution being geographically isolated for thousands of years. Here, we present a high-quality de novo assembly of a pure dingo (CanFam_DDS). We identified large chromosomal differences relative to the current dog reference (CanFam3.1) and confirmed no expanded pancreatic amylase gene as found in breed dogs. Phylogenetic analyses using variant pairwise matrices show that the dingo is distinct from five breed dogs with 100% bootstrap support when using Greenland wolf as the outgroup. Functionally, we observe differences in methylation patterns between the dingo and German shepherd dog genomes and differences in serum biochemistry and microbiome makeup. Our results suggest that distinct demographic and environmental conditions have shaped the dingo genome. In contrast, artificial human selection has likely shaped the genomes of domestic breed dogs after divergence from the dingo.
Pet food represents a large share of the U.S. economy, and the majority of it is produced through extrusion. Starches comprise between 30-60% of extruded dog foods and sources include cereals, tubers, legumes, and co-products from the human food chain. Starches are well digested and metabolized by dogs, with variations according to food processing parameters, starch source, and dog breed. Dogs have a higher expression of enzymes related to starch digestion, glucose absorption and metabolism compared to the wolf. Several studies have reported that starch total tract apparent digestibility (ATTD) by dogs is well above 95%. Although starches are not required by dogs, they are an important source of energy and provide structure and binding of kibbles. The degree of starch digestion depends on factors like granular structure, amylose: amylopectin ratio, degree of gelatinization, and other nutrients present in the food matrix such as fibers, lipids and proteins. Tubers and legumes are well utilized by dogs, but most times require heat treatment to deactivate anti-nutritional factors and improve digestibility, while cereal starches seem to be well digested even in their raw form. Slowly digestible or resistant starches may contribute to satiety, lower glucose and insulin responses and improved colonic microbiota. In conclusion, there is enough evidence supporting that properly processed cereals and tubers included in dog foods are digestible, palatable and do not present health concerns, but the scientific literature lacks information on pulses, ancient grains, and food processes beyond extrusion.
The aim of this review was to summarise the available literature on the effects of consuming raw red meat diets on the gastrointestinal microbiome of the cat and dog. In recent years, feeding raw meat diets to cat and dogs has increased, in part associated with trends in human nutrition for “natural” and “species-appropriate” diets. These diets range from home-prepared unprocessed, nutritionally incomplete diets to complete and balanced diets with sterilisation steps in their manufacturing process. Feeding some formats of raw meat diets has been associated with nutritional inadequacies and zoonotic transfer of pathogens. The feeding of raw meat diets has been shown to alter the gastrointestinal microbiome of the cat and dog, increasing the relative abundances of bacteria associated with protein and fat utilisation, including members of the genera Fusobacterium and Clostridium. While in humans, these genera are more commonly known for members that are associated with disease, they are a diverse group that also contains harmless commensals that are a normal component of the gastrointestinal microbiota. Moreover, members of these genera are known to produce butyrate from protein and amino acid fermentation and contribute to intestinal homeostasis in raw meat-fed dogs and cats. Currently, only a limited number of studies have examined the impacts of raw meat diets on the cat and dog microbiota, with many of these being descriptive. Additional controlled and systems-based studies are required to functionally characterise the roles of key microbial groups in the metabolism of raw meat diets, and determine their impacts on the health and nutrition of the host.
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Studies of feeding patch choice in primates have traditionally analyzed individual foraging decisions in relation to patterns of social foraging, dominance, and feeding competition. However, information on detailed ecological and nutritional characteristics of the patches also is needed to understand the basis of feeding patch preferences. In particular, recent models of nutritional ecology have stressed the importance of nutrient balancing as a primary driver of individual foraging decisions. Here we investigated the behavioral and nutritional factors affecting feeding patch choice in black howler monkeys (Alouatta pigra) during a 15-month field study in Campeche, Mexico. We collected 1300 hours of behavioral data on 14 focal animals, including full-day follows of one individual/day recording all feeding activities. We carried out nutritional analyses of foods from feeding trees and calculated daily nutrient intake. A total of 690 trees (i.e., patches) were visited throughout the study period. The time spent feeding and the amount of food consumed differed significantly according to patch type. Individuals consumed more food in mature and immature fruit patches than in mature leaf, young leaf, and flower patches. Protein intake rates (kJoule/min) were similar in young and mature leaf patches, and higher than in mature fruit, immature fruit, and flower patches, among which the rate was similar. In the majority of the cases (80.3%), the focal animals left the feeding patch prior to satiation. On those occasions, resource mixing, or moving from one food type to another food type, accounted for 49.4% of the patch leaving events. The fact that black howler monkeys alternated feeding bouts between fruit and leaf patches, as well as alternating bouts of higher and lower protein intake, suggest that this pattern could be dictated by the need to balance nutrients. Journal of Behavior, Health & Social Issues. Vol. 12, Num. 2 (2020) pp. 55-68
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Why do dogs behave in the ways that they do? Why did our ancestors tame wolves? How have we ended up with so many breeds of dog, and how can we understand their role in contemporary human society? Explore the answers to these questions and many more in this study of the domestic dog. Building on the strengths of the first edition, this much-anticipated update incorporates two decades of new evidence and discoveries on dog evolution, behavior, training, and human interaction. It includes seven entirely new chapters covering topics such as behavioral modification and training, dog population management, the molecular evidence for dog domestication, canine behavioral genetics, cognition, and the impact of free-roaming dogs on wildlife conservation. It is an ideal volume for anyone interested in dogs and their evolution, behavior and ever-changing roles in society. The ultimate book about the domestic dog, ideal for anyone interested in their evolution, behavior and ever-changing roles in society A new edition of a classic text, presenting the latest research on dog behavior, training, domestication, genetics and cognition Includes seven entirely new chapters by leading experts in the field, incorporating two decades of new evidence and discoveries.
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There is a large body of research demonstrating that macronutrient balancing is a primary driver of foraging in herbivores and omnivores, and more recently, it has been shown to occur in carnivores. However, the extent to which macronutrient selection in carnivores may be influenced by organoleptic properties (e.g. flavour/aroma) remains unknown. Here, we explore the roles of nutritional and hedonic factors in food choice and macronutrient balancing in a mammalian carnivore, the domestic cat. Using the geometric framework, we determined the amounts and ratio of protein and fat intake in cats allowed to select from combinations of three foods that varied in protein : fat (P : F) composition (approx. 10 : 90, 40 : 60 and 70 : 30 on a per cent energy basis) to which flavours of different 'attractiveness' (fish, rabbit and orange) were added. In two studies, in which animal and plant protein sources were used, respectively, the ratio and amounts of protein and fat intake were very consistent across all groups regardless of flavour combination, indicating regulation of both protein and fat intake. Our results suggest that macronutrient balancing rather than hedonistic rewards based on organoleptic properties of food is a primary driver of longer-term food selection and intake in domestic cats.
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The geographic and temporal origins of dogs remain controversial. We generated genetic sequences from 59 ancient dogs and a complete (28x) genome of a late Neolithic dog (dated to ~4800 calendar years before the present) from Ireland. Our analyses revealed a deep split separating modern East Asian and Western Eurasian dogs. Surprisingly, the date of this divergence (~14,000 to 6400 years ago) occurs commensurate with, or several millennia after, the first appearance of dogs in Europe and East Asia. Additional analyses of ancient and modern mitochondrial DNA revealed a sharp discontinuity in haplotype frequencies in Europe. Combined, these results suggest that dogs may have been domesticated independently in Eastern and Western Eurasia from distinct wolf populations. East Eurasian dogs were then possibly transported to Europe with people, where they partially replaced European Paleolithic dogs.
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Domestic dogs diverged from grey wolves between 13 000 and 17 000 years ago when food waste from human settlements provided a new niche. Compared to the carnivorous cat, modern-day dogs differ in several digestive and metabolic traits that appear to be more associated with omnivorous such as man, pigs and rats. This has led to the classification of dogs as omnivores, but the origin of these ‘omnivorous’ traits has, hitherto, been left unexplained. We discuss the foraging ecology of wild wolves and calculate the nutrient profiles of fifty diets reported in the literature. Data on the feeding ecology of wolves indicate that wolves are true carnivores consuming a negligible amount of vegetal matter. Wolves can experience prolonged times of famine during low prey availability while, after a successful hunt, the intake of foods and nutrients can be excessive. As a result of a ‘feast and famine’ lifestyle, wolves need to cope with a highly variable nutrient intake requiring an adaptable metabolism, which is still functional in our modern-day dogs. The nutritive characteristics of commercial foods differ in several aspects from the dog’s closest free-living ancestor in terms of dietary nutrient profile and this may pose physiological and metabolic challenges. The present study provides new insights into dog nutrition and contributes to the ongoing optimisation of foods for pet dogs.
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A recent area of progress in nutritional ecology is a growing awareness that nutritional phenotypes are best understood in a multidimensional context, where foraging is viewed as a process of balancing the intake and use of multiple nutrients to satisfy complex and dynamic nutrient needs. Numerous laboratory studies have shown that this view can yield novel insights into unresolved questions and provide a framework for generating new hypotheses. By contrast, progress with this multidimensional view has been slow in the arena of ultimate interest to functional biologists, the field. One reason for this is that the Geometric Framework for nutrition that has been extensively used in laboratory experiments focuses on amounts of nutrients (e.g., required, eaten, or retained), and such data are typically very difficult or impossible to collect for most free-ranging animals. Further, many problems in field-based nutritional ecology involve comparisons of mixtures that are expressed as proportions (e.g., food, diet, body, or fecal compositions), rather than absolute amounts. As yet, however, no geometric framework has been established in nutritional ecology for this. Here I recommend an approach for the geometric analysis of nutritional mixtures, and illustrate its use in a variety of contexts by reanalyzing published data. Despite its simplicity, this approach holds considerable promise for furthering the study of field-based nutritional ecology.
Cats are obligate carnivores adapted to high-protein diets, but are commonly fed diets rich in carbohydrate. The aim of this study was to examine the food intake choices of cats when diets with different protein and carbohydrate contents were offered. Thirty-nine cats participated in voluntary dietary intake studies. Four foods were formulated to provide between 24% and 53% of metabolizable energy as protein, between 43% and 11% as carbohydrate and holding dietary fat constant with a contribution of approximately 36%. Foods were offered either singly to evaluate voluntary food intake or in pairs to compare food intake between pairs of diets. Cats regulated their macronutrient intake to attain an overall diet composition that provided 53% of metabolizable energy as protein, 11% as carbohydrate and 36% as fat. The protein contribution corresponded to approximately 6 g of protein/kg body weight/day. High-protein/low-carbohydrate diets were always eaten preferentially over low-protein/high-carbohydrate foods. When low-protein/high-carbohydrate diets were offered, cats limited their food intake to limit daily carbohydrate intake to less than 3 g of carbohydrate/kg body weight. This carbohydrate ceiling may limit protein and even energy intake when only low-protein/high-carbohydrate diets were offered. The inclusion of palatability enhancer in the diets increased food intake but did not change protein or carbohydrate intake patterns, indicating that macronutrient intake can be regulated regardless of the use of palatability enhancers in cats. We conclude that cats can discriminate between diets based on macronutrient composition and regulate their intake to maintain maximal protein intake but limit carbohydrate intake.
Conference Paper
Obesity is defined as an accumulation of excessive amounts of adipose tissue in the body, and is the most common nutritional disorder in companion animals. Obesity is usually the result of either excessive dietary intake or inadequate energy utilization, which causes a state of positive energy balance. Numerous factors may predispose an individual to obesity including genetics, the amount of physical activity, and the energy content of the diet. The main medical concern of obesity relates to the many disease associations that accompany the adiposity. Numerous studies demonstrated that obesity can have detrimental effects on the health and longevity of dogs and cats. The problems to which obese companion animals may be predisposed include orthopedic disease, diabetes mellitus, abnormalities in circulating lipid profiles, cardiorespiratory disease, urinary disorders, reproductive disorders, neoplasia (mammary tumors, transitional cell carcinoma), dermatological diseases, and anesthetic complications. The main therapeutic options for obesity in companion animals include dietary management and increasing physical activity. Although no pharmaceutical compounds are yet licensed for weight loss in dogs and cats, it is envisaged that such agents will be available in the future. Dietary therapy forms the cornerstone of weight management in dogs and cats, but increasing exercise and behavioral management form useful adjuncts. There is a need to increase the awareness of companion animal obesity as a serious medical concern within the veterinary profession.
Objective: To develop morphometric equations for prediction of body composition and create a body fat index (BFI) to estimate body fat percentage in overweight and obese dogs. Design: Prospective evaluation study. Animals: 83 overweight or obese dogs ≥ 1 year of age. Procedures: Body condition score (BCS) was assessed on a 5-point scale, morphometric measurements were made, and visual and palpation-based assessments and dual-energy x-ray absorptiometry (DEXA) were performed. Equations for predicting lean body mass, fat mass, and body fat as a percentage of total body weight (ie, body fat percentage) on the basis of morphometric measurements were generated with best-fit statistical models. Visual and palpation-based descriptors were used to develop a BFI. Predicted values for body composition components were compared with DEXA-measured values. Results: For the study population, the developed morphometric equations accounted for 98% of the variation in lean body mass and fat mass and 82% of the variation in body fat percentage. The proportion of dogs with predicted values within 10% of the DEXA values was 66 of 83 (80%) for lean body mass, 56 of 83 (68%) for fat mass, and 56 of 83 (67%) for body fat percentage. The BFI accurately predicted body fat percentage in 25 of 47 (53%) dogs, whereas the value predicted with BCS was accurate in 6 of 47 (13%) dogs. Conclusions and clinical relevance: Morphometric measurements and the BFI appeared to be more accurate than the 5-point BCS method for estimation of body fat percentage in overweight and obese dogs. Further research is needed to assess the applicability of these findings to other populations of dogs.