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Clin ical Nutr ition

Evaluation of Nutrient utilization in the Canineusing the H eal C annulation Technique1-3JULIE A. WALKER* DAVID L. HARMON,** KATHY L. GROSSI ATVDGEORGE F. COLL//VGStDepartm ent of Anim al Sciences, University of K entucky, Lexington, KY 40546; andtM ar/c M orris Associates, Topeka, K S 66601

A BSTRACT N ine m ature m ongrel dogs w ere used toeva lu ate a s urg ic al te ch niq ue fo r th e c an nu la tio n o f th eterm inal ileum and used in tw o experim ents to determ ine the effect of carbohydrate source on starch andd ry ma tte r d ig es tio n. Dog s (1 6.2 2 .0 k g body weig ht;m eans SD) w ere fitted w ith an lealT -cannu la constructed of p olyvinyl chloride pipe. T he cannula w asinserted into the term inal ileum ~10 cm proxim al toth e ile oc ec al ju nc tio n and th e c an nu la w as exte rio riz edthrough a sm all incision on the right flank. Dogs recover ed qui ck ly f rom sur ge ry ( 5 d ). A p re lim inar y s tudyu sing C nEDTA in the food indicated th at sam pling for1 2 h p ostp ra nd ia lly a llowe d n ea r c omple te re pre se nta tio n o f d ig esta flow fo r a m ea l; p ea k flow o cc urre d 4 -to 8 -h p os tfe ed in g. Two e xp erim en ts w ere p erfo rm edevaluatin g the effect of carbohydrate source on lea lsta rc h a nd d ry m atte r d ig estib ility . D og s w ere fe d tw omea ls d aily w ith C r2O3 use d a s a d ig esta m ark er. D ie tscon ta in ed 67% ex tr uded g ra in ( co rn , r ic e, o a ts o r bar ley)and 33% canned m eat supplem ent on a dry m atter basis. S ta rc h d ig estio n w as c omple te (> 98% ) w ith in th esm all intestine a nd w as una ffected by c arbohydratesource. In experim ent 1, prececal and total tract drym atter digestib ilities w ere highe r for rice than co rn,and in expe rim ent 2, barley w as high er than oats. T he le al - ca nn ula a llows fo r meas uremen t o f small in te stin al n ut rie nt d is ap pe ara nc e w ith ou t th e con fo un din ge ff ec ts o f colon ie micr of lo ra . Th is me thod may be u se fu lw hen applied to the study of oth er nutrie nts in d ogs.J. N utr. 124:267 28-26768, 1994.IN DE XIN G K EY WORDS :dogs l eumsta rch . cannula t ion diges tion

N utrient digestion and absorption is incom pletew hen digesta reaches the term inal ileum of m ost anim als. D igesta flow ing to the colon is further alteredb y th e m ic ro flo ra , m akin g an ac cu rate d eterm in atio no f m ammalian n utrien t d ig estio n an d ab so rp tio n fromtotal fecal collections im possible. Changes in dietcom position, such as grain source and fiber content0022-3166/94 $3.00 1994 A merican Institute of N utrition.

(F ahey et al. 1990), m ay influence the degree of alteration in the colon. Studies in livestock species (Bocket al. 1991, Kohler et al. 1990) and dogs (Brass andS chun emann 1989) h av e employed in te stin al c annu la sto perm it sam pling of digesta at various points in thedigestive tract and thereby rem ove the contributionof the post-sm all intestinal m icroflora. T he purposeof our research w as to determ ine if these m ethods forin te stin al c annu la tio n cou ld b e su cc essfu lly a pp lie d inthe dog and to determ ine intestinal digestion of diff er en t car bohydr ate s ou rces .

M ATERIALS AND M ETHODSThe use and handling of anim als for these experim ents w ere approved by the U niversity of K entuckyanim al care com mittee (Protocol 92-0002A ). Dogsw ere adapted to Elizabethan collars (plastic funnelshaped collars) before the start of the experim ents.Initially, collars w ere placed on the dogs for short periods of time (2-4 h) and then time was increasedgradually. T his perm itted the dogs to be accustom edto handling and allow ed us to identify any potentialbehavior problem s. A ll dogs w ere able to consum e w ater from the nipple w aterers w ith the collars on. D ogswere exercised twice daily in groups of tw o or three1 Presented as part of the W altham S ym posium on the N utritionof C om panion A nim als in association w ith the 15th InternationalC ongress of N utrition, at A delaide, SA , A ustralia, on S eptem ber

23-25, 1993. Guest editors for this symposium were Kay EarleJohn M ercer and D 'A nn Finley.2 P ortions of this data w ere presented previously: W alker, J. AHarmon, D. L., Gross, K . L. and Collings, G . (1993) Effect of carbohydrate source on starch digestibility in the dog. J. Anim. Sc7 1(su pp l. 1 ): 1 59 .3 A pproved by the D irector of the K entucky A gricultural E xperim ent S tation as P ublication N o. 93-5-166.4 T o w hom correspondence should be addressed: 805 W .P. G arrigus B ldg., U niversity of K entucky, L exington, K Y 40546.

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ILEA L NUTR IENT DIGEST ION IN THE DOG 2673Sfor 20 m in before feeding. Dogs w ere giv en the testfood in a stainless steel bow l at 0700 and 1800 andallow ed 30 m in to consum e the food throughout allexperim ents. M ost of the dogs consum ed the foodw ithin 15 m in. B ow ls w ere rem oved from the cageaf ter 30 m in and orts w ere recorded. T he dogs w erehoused in an env ironm entally controlled room at 22 Cand a 14-10 light-dark cy cle. Dogs w ere housed instainless steel cages (1.2 X 1.8 m ) w ith steps (1.07X 0.46 m ). A raised holed m at (1.2 X 0.9 m ) w as alsoprov ided in each cage.N ine dogs [16.2 2.0 kg body w eight (B W ); m eans D ]5 w ere surgically f itted w ith ileal T -cannula. Foodw as rem oved 24 h before surgery . Dogs w ere prem ed-icated 1 d before surgery w ith cefadrox il (2.2 m g/kgBW , b.i.d.) and 2 d af ter surgery . A nim als w ere consum ing food 12 h af ter surgery and w ere back to fullintak es w ithin 5 d of surgery .Ca n n u la con str u ction . Th e T-sh a ped ca n n u law as constructed from a 1.25-em OD poly v iny l chloride (PV C) "T " f itting (Fig. 1). T he top half of the "T "w as cut of f and the barrel inside diam eter w as drilledto 1.1 cm . T he ridges on the PV C pipe w ere rem ovedby sanding. T he portions of the cannula to be placedw ithin the intestinal lum en w ere rounded and curv edaw ay from the intestine to reduce any possible irritation. T his w as accom plished by heating the PV C pipew ith a blow dry er and bending the ends. T he cannulaw as f inished w ith f ine em ery cloth, w ashed w ith Ivorysoap (Procter and Gam ble, Cincinnati, OH), and gassteriliz ed. T he barrel length of each cannula w as adjusted for each anim al af ter the postsurgery sw ellinghad disappeared so hose clam ps w ere f lush w ith theend. T his w as accom plished using a PV C pipe cutter(R igid M odel N o. 138, W . W . Grainger, L ex ington,K Y ). T he cannula plug (length 2.5-2.8 cm ) w as constructed from a cotter pin and tw o 1-cm w ashers enclosing a rubber hose to f it snugly inside the barrel ofthe cannula. T he plug w as then easily rem oved w ithforceps; how ever, the dogs w ere unable to rem ove it.Su rgica l procedu re. Dogs were premedica ted withatropine (0.05 m g/k g) im mediately before surgery .General anesthesia w as induced w ith sodium thia-m ylal (20 m g/kg) and m aintained using halothane vaporiz ed in ox ygen and deliv ered through a sem iclosedcircuit sy stem . Dogs w ere placed in lef t lateral recumbency for the surgical procedure. T he f lank area w asprep ared aseptically and the abdom inal cav ity accessedthrough a 7- to 10-cm incision located ~ 5 cm posteriorand parallel to the last rib. T he cecum w as located andthe apex ex terioriz ed to perm it location of the term inalileum for placem ent of the cannula. A 5-cm longitudinal incision w as m ade in the antim esenteric borderof the intestine to perm it insertion of the cannula.T he incision in the intestine w as closed using an in-

5 A b brev iations: B W , body w eight; CP, crude protein; D M , drymatter.

r_

1 .5cm1 .1 c m

Ave . 5 .3 cm -

L 2 .5 cm J L 2 . 5cm JF IGURE 1 Dia gr a m of polyvin yl ch lor ide ilea l ca n n ulaused in dogs.

v erting suture pattern w ith 2-0 V icry l suture. Carew as tak en to inv ert all m ucosa and secure the intestinetightly around the barrel of the cannula. T he barrel ofthe cannula w as then ex terioriz ed through a stab incision in the right f lank , cranial to the incision, andsecured w ith an ex terior ny lon w asher and plugged.T he abdom inal cav ity w as then lavaged w ith sterileph ysiological saline (39 C )con taining 1 m illio n u nitspotassium penicillin. T he peritoneum and m uscle fascia w ere then opposed in a continuous pattern using2-0 V icry l suture and the sk in closed w ith 2-0 ny lon.

P relim in a ry exper imen t. F ive dogs were u sed inan experim ent to evaluate digesta f low patterns andileal digesta collection procedures. T he m orning f eeding w as presented at 0700 containing 209 tig of Cr:EDTA /g of food. T he f irst ileal digesta sam ple w ascollected from 0730 to 0900 and then hourly sam plesw ere collected until 1900. Indiv idual sam ples w erek ept on ice during the collection period then frozen(-20 C) until analy zed for Cr. S am ples w ere thaw ed,m ix ed and l g of w et ileal digesta w as diluted w ith 9m L w ater, m ix ed and centrifuged, and Cr concentrations w ere determ ined by atom ic absorption spectros-copy . Ileal Cr concentrations w ere used to estim atedigesta f low patterns and areas w ere calculated as described by Galy ean (1993) to estim ate total f low .Diets. D iets were formu la ted to con ta in 67% othe ex truded carbohydrate source and 33% cannedm eat-based supplem ent on a dry m atter (DM ) basis(T able 1). C arbohy drate sources w ere ex truded grains:corn, rice, barley or oats. T he grains w ere reduced inparticle siz e through a 1.18-m m screen and thencooked and form ed using an A PV tw in screw ex truder(A PV -B ak er, Grand R apids, M I) w ith an ex it tem perature of 138 C.T he ex truded product w as dried inhot air dry er to 8% m oisture. Chrom ic ox ide (0.2% ototal diet DM ) w as used as a digesta m ark er and w aspart of the m eat-based supplem ent. Diets w ere pre-

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2674S SUPPLEMENTTABLE 1

Chemical composition of diets fed to dogs1Item Corn Rice Barley OatsDM ,CP,%Ca,P,%ME,A/ /gStarch,Crude f iber, %36 .623.9

0.400.5615.747.7'2.6536.023.1.440.5414.657 .b0.5825.426.2

0.420.5815.243.6'1.9125.426.10.440.5814.40.1"12.1

1 Final diets w ere 67% ex truded grain source and 33% m eat-based supplem ent. T he com position of the m eat-based supplem entw as (as-f ed basis) 52.7% w ater, 17.4% corn, 13.6% chick en, 8.0%m eat by -product, 3.8% soybean m eal, 3.8% liv er, 0.3% soy oil,0.18% calcium carbonate, 0.11% sodium chloride, 0.05% cholinechloride, 0.04% iron ox ide, 0.04% v itam in m ix and 0.03% m ineralm ix and contained 23.7% DM, 46.8% C P, 1.1% C rude f iber, 0.93%Ca, 0.93% P, 0.06% M g, 0.80% K , 0.46% Na, and 0.80% Cl on ad ry bas is ."beans w ith unlik e superscripts dif fer (P < 0.01) w ithin thesam e ex perim ent (corn v s. rice and barley v s. oats).DM = dry m atter; CP = crude protein; M E = m etaboliz able energy.

pared by m ix ing the m eat-based supplem ent and extruded grains in 4-d quantities and stored in the ref rig erato r u ntil f ed . T h e e x tru ded carboh ydrate so urc ewas added to th e meat-b ase d supp lemen t as h alf -w holee xtrud ed k ib bles an d h alf -g ro und ex tru ded g rain . B efore each feeding the m ix ed diets w ere w eighed and~ 125 g of hot tap w ater w as added to w arm the food.Exper iment 1. Seven mature mongrel dogs (16.7 1.1 k g B W ) w ere fed diets of ex truded corn or extruded rice in a tw o-period crossov er design ex perim ent. Each ex perim ental period consisted of 17 d: 10d of adaptation to diets, 4 d of total fecal collectionan d 3 d of ileal d ig esta co lle ctio n. Fe cal samp les w e recollected at both feeding periods and anim als w ereclo se ly o bse rv ed d uring ex erc ise f or ad ditio nal f ec es.Fec es w e re w e ig he d an d th en ad de d to a p oo led samp le.During ileal d iges ta colle ction, th e E liz abethan coll arsw e re p lace d on the d og imme diate ly af te r th e mo rn in gfeeding and rem oved before the ev ening feeding.Hourly ileal sam ples w ere collected ov er 3 d. On d 1the starting tim es w ere 1000, 1300 and 1600; d 2 thestarting tim es w ere 0900, 1200 and 1500 and d 3 thestarting tim es w ere 0800, 1100, 1400 and 1700. Ilealdigesta collection w as done by rem o ving the cannulaplug and digesta in the cannula w as scraped out w itha sm all spatula to ensure collection of f resh digesta.Ileal digesta w as collected into a sm all plastic bag secured to the cannula for 1 h. Ev ery 15 m in dogs w ereobserv ed to check the status of the bags. If bags w eref ull, a second bag replaced the f irst. A t the end of eachcollection, the right side of each dog around the cannula w as rinsed w ith an iodine solution to rem ov e di-gesta that could irritate the sk in. Ileal digesta w as

tran sporte d to th e laborato ry on ic e and hou rly samp le sw ere w eighed, recorded and pooled f or each dog.Exper iment 2. Six of the seven mature mongreldogs (18.2 1.1 k g B W ) used in ex perim ent 1 w eref ed diets of ex truded barley or ex truded w hole oats.Fe ed in g and s amp lin g p ro cedu re s w e re sim i lar to th osedescribed in ex perim ent 1.Analyses. D iet, ileal digesta and fecal samplesw ere ly ophiliz ed and ground in a comm e rcial blenderuntil sam ples w ere f ine and hom ogenous. D iet sub-sam ples w ere ground through a 1-m m screen in aW ile y m i ll. S amp le s w e re sto re d in p lastic b ag s at ro omtempe ratu re until an aly sis f or C r (W illiam s e t al. 1 962)and s tarch (Herre ra-Saldana and Huber 1989) . G luco seco nce ntratio n f rom th e starch d ig est w as d eterm in edusin g a g lu cose an aly z er (Mo de l 2 300 , Y e llow S prin gsInst., Y ellow S prings, OH). N utrient digestibilitiesw ere calculated from Cr ratios using equations described by M erchen (1988). D ata w ere analy zed byanaly sis o f v arian ce p ro cedu re s f or a c ro sso v er d esig nex perim ent as described by S teel and T orrie (1980).T reatm ent m eans w ere considered dif f erent if P< 0 .0 5.

R ESUL TS A N D DISCUSS IONA ll nine dogs recov ered f rom and w ere f unctionalaf ter surgery ; how ev er, only eight w ere used in experim ents. O ne w as k illed due to incessant chew ingon his cannula. H ose clam p s prev ented the dogs f romch ew in g an d d amag in g th e can nu la an d mo st paid littleattention to the cannula once they realiz ed they couldnot dam age it and w ere unable to rem ov e the plug. Itw as critical th at n o p ortion o f th e plu g p ro tru ded f romthe cannula to prev ent the dogs f rom rem o ving it. T heh ose clamp o n th e c an nu la w as ch ec ked d aily , b ecau senorm al m ov em ent of the dogs w ould som etim esloosen the hose clam p and allow the cannula to bep ulle d back in to th e in te stin al lum en . T he can nu la w aseasily retriev ed w ith f orceps, but this required anesth etiz ing the d og.R ectal body tem peratures w ere m onitored for 7 dpostsurgery . Four of the nine dogs had elev ated temp eratu re s (>3 9.5 C )p ostsurg ery , b ut n on e w e re o bse rv ed af ter 3 d p ostsurg ery . W ith in 1 4 d af te r surg ery ,d og s w e re ru nn in g, jump in g and in te rac tin g w i th o th erdogs. T he prim ary reason f or rem o ving dogs f rom thestudy w as subcutaneous infections around the cann ula. A l l in fe ctio ns w e re lo caliz ed su bcu tane ou sly .B rass an d S ch un eman n (1 98 9) re porte d sim ilar p ro blem s w ith ileal cannulation in dogs. It appeared thatirritation s aro un d th e b arre l o f th e c an nu la p re ce dedth e su bcutan eous in fe ctio ns. T h is p ro blem was p re se ntm ore at the beginning of the ex perim ent w hen thecannula plugs had an ex ternal steel nut and dogsseem ed to chew on these m uch m ore. Cannula plugs

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ILEA L NUTR IENT DIGEST ION IN THE DOG 2675Sthat f it entirely inside the cannula barrel seem ed tored uce this problem .P relim in a ry E xper imen t. Th e in itia l pu lse dosew ith Cr:EDTA show ed that the m ost of the digestaf low occurred during the period of 4-8 h postfeeding(data not show n). Calculating the area under the curv efor 12 h postfeeding allow ed the estim ation of thepercentage of total CrEDT A that w as recovered ov erthis tim e interval. Estim ates ranged from 58 to 96%w ith an overall m ean of 73%. S im ilar recov eries ofm ark er w ere reported for pigs f itted w ith ileal T -can-nulas (K ohler et al. 1990). B ased on these digesta f lowcharacteristics, sam ples w ere collected ov er the entireinterval betw een a.m . and p.m . feedings to representas m uch of an indiv idual m eal as possible. A lso samples w ere collected over a 3-d period to help reducevariability f rom only one sam pling day .E xper imen t 1. Th e extru ded r ice diet con ta in ed10% m ore starch than the corn diet (T able 1) due tothe higher starch content of rice. T he average dailyintak es of the test m eals w ere sim ilar betw een the cornand rice diets (T able 2). Prececal and total tract starchdigestibility w as not af fected by carbohy drate source,w ith starch digestion alm ost com plete at the term inalileum (99.4 and 99.5% f or corn and rice, respectiv ely ).Prececal and total tract DM digestion w as inf luenced by carbohydrate source (T able 2). Corn had alow er DM digestion (82.1 and 87.2% for the ileal andfecal sites, respectiv ely ) than rice (88.2 and 91.5% forth e ileal an d f ecal sites, resp ectiv ely ). T h ese d if feren cesare probably due to the am ount of f iber in the carbohy drate source. T he corn diet had a crude f iber contentthat w as 2.65% com pared w ith 0.58% for the rice.

E xper im en t 2. Th e ba r ley diet (43.6% ) con ta in edm ore starch (T able 1 ) than the w hole oats (30.1% ) dueto the higher starch content of barley . T he daily DMintak es w ere not af fected by carbohydrate source (T able 2). Prececal and total tract starch digestion w erenot af fected by carbohydrate source tested. Ileal andtotal DM digestib ilities w ere af fected by carboh ydratesource (T able 2). T he w hole oat diet had a low er DM

digestion at both the ileal and fecal collection sites(66.1 and 70.4% , respectiv ely ) com pared w ith the barley (79.7 and 84.6%, respectiv ely ). A gain, these differences m ay be due in part to the f iber content of thediet w ith the barley diet hav ing a 1.91% crude f ibeand the w hole oats diet hav ing 12.1% crude f iber.T hese tw o ex perim ents dem onstrated that dogs arecapable of digesting high (30-57%) starch diets andprececal and total tract digestion v alues f or starch w erequite sim ilar, w ith no adverse ef fect seen in the dogs.Dogs gained w eight throughout the experim ents.B aker and Czarneck i-M aulden (1991) reported thatcook ing w as essential for adequate starch digestion inpuppies, w hereas M oore et al. (1980) evaluated uncooked or cooked grain sources (rice, oats and corn)using adult dogs and found that total starch digestibility w as sim ilar for cooked and uncooked rice(>98%) and corn (>94%); how ever, cooked oats hadhigher digestibility (96%) com pared w ith uncook ed(94% ). S chunem ann et al. (1989) reported prececal digestibilities in dogs of 0, 94 and 47-67% for raw potato, raw corn and raw tapioca, respectiv ely , suggestingthat starch digestibility appears to vary due to starchsource. T hey also reported that apparent digestibilityfor corn w as 99% for f inely m illed corn but only 69%for crudely ground corn. T his w ork dem onstrates thatprocessing play s an im portant factor in starch digestibility.B ecause starch digestion w as essentially com plete,v ariation in f iber content resulted in variation in DMdigestibility . R ice had the low est f iber content and thehighest DM digestibility , w hereas the high f iber content of oats resulted in the low est DM digestibility .M oore et al. (1980) fed cereal-based stock diets andreported total tract DM digestibilities f rom 78 to 86%for corn and rice w ith oats interm ediate. Our resultsshow that total tract DM digestibilities for corn andrice w ere higher; this m ay be due to dif ferences in theex trusion process. H ow ev er, our results indicated totaltract DM digestibility for w hole oats w as low er, probably because the hulls w ere included in the ex truded

T ABL E 2In take an d digestibility for dogs fed diets con ta in in g corn , r ice, ba r ley an d oa ts

I temDM1intake,/dPrececal

digestibility,StarchDMTotaldigestibility,StarchDM Corn27399.482.1'99.887.2'Experiment

1Rice25999.588.2b99.991.5"SEM 210.190.740.030.84Barley29398.879.7'99.884.6'ExperimentOats31298.566.1b99.870.4

1 DM , dry m atter.*/bM eans w ith unlik e superscripts dif fer (P < 0.01) w ithin the sam e ex perim ent (corn v s. rice and barley v s. oats).

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2676S SUPPLEMENTproduct. T hese dif ferences m ay also be inf luenced byanim al siz e and food intak e. T he dogs used by M ooreet al. (1980) w ere larger (23 k g) and w ere consum ingm ore food per k illigram BW .M ost dog f oods contain large am ounts of grains toex trude the f inal food properly , as w ell as to prov idek ey nutrients. T he ability of the dog to utiliz e highlev els of starch as an energy source is a k ey to thedev elopm ent of dog foods in the future. T he determ ination of precacal nutrient digestion and the m e asurem ent of nutrient passage supply ing substrate f orcolonie f erm entation w ill aid in the future dev elopm ent of m odels to m ore critically ev aluate nutrientutiliz ation in the dog.

ACKNOWLEDGMENTSW e ex tend our thank s to Joseph C lark , S enior Food

S cien tist, an d T ed K u lp insk i, S en io r Fo od S cie ntist, inth e Man uf acturin g E ng in ee rin g T ec hn olo gy C en ter o fH ill's Pet N utrition f or ex truding, canning and packag in g th e te st d iets.

L IT ER A TUR E CIT EDB ak er, D . H . & C zarneck i-M aulden, G . L . (1991) C om parativ en utritio n o f cats an d do gs. A n nu. R ev . N u tr. 1 1: 2 3 9-2 63.B ock , B . } ., H arm on, D . L ., B randt, R . T ., Jr. & S chneider, J. E.(19 91 ) Fat so urce an d calciu m lev el ef fects o n f in ish in g steer

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