Passage of Feed Through the Adult Rooster1

Passage of Feed Through the Adult Rooster1 I.R. SIBBALD Animal Research Institute, Agriculture Canada, Central Experimental Farm, Ottawa, Ontario, Canada K1A 0C6 (Received for publication July 19, 1978)

1979 Poultry Sci 58:446-459 INTRODUCTION The bioassay for t r u e metabolizable energy (TME) involves placing a k n o w n weight of feed in the crop of a starved bird and collecting t h e excreta voided during t h e subsequent 24 hr (Sibbald, 1 9 7 6 a ) ; it is assumed t h a t feed passes through t h e alimentary canal within 2 4 hr. T h e assumption has n o t been tested b u t t h e low standard errors of most m e a n TME values, coupled with t h e good agreement b e t w e e n d a t a obtained in collaborative studies (Sibbald, 1 9 7 7 ; Kessler and T h o m a s , 1 9 7 8 ) , suggest t h a t it is reasonable. However, recent w o r k has s h o w n that small quantities of rapeseed hulls, from rapeseed meal, were voided after t h e 2 4 hr collection period had elapsed (Sibbald, 1 9 7 8 ) . This led t o t h e hypothesis t h a t t h e relatively high standard errors associated with t h e m e a n TME values of high-fiber materials such as w h e a t bran (Sibbald, 1 9 7 6 b ) and alfalfa (Sibbald and Likuski, unpublished data) may be d u e t o incomplete passage in 2 4 hr. T h e hypothesis was

'Contribution number 773 Animal Research Institute.

tested b y Jones and Sibbald ( 1 9 7 8 ) w h o measured t h e TME values of 11 rapeseed fractions using b o t h 24 and 4 8 hr collection periods. T h e TME value of ground whole rapeseed decreased significantly w h e n t h e collection period was ext e n d e d b u t t h e differences associated with t h e o t h e r rapeseed fractions, which included such fibrous materials as h e x a n e extracted hulls, were n o t statistically significant. T h u s , while it was shown t h a t s o m e feedingstuffs d o n o t clear t h e alimentary tract within 2 4 hr of being placed in t h e crop of a starved bird it b e c a m e a p p a r e n t t h a t slow passage was n o t necessarily associated with a high level of fiber. As t h e basic m e t h o d o l o g y of t h e TME bioassay is being applied t o t h e m e a s u r e m e n t of t h e availabilities of energy, and a variety of n u t r i e n t s including amino acids, lipids, and minerals, it is i m p o r t a n t t h a t information o n t h e time required t o clear t h e alimentary t r a c t be obtained for several feedingstuffs. There are r e p o r t s concerning t h e rate of passage of feed t h r o u g h p o u l t r y . Browne ( 1 9 2 2 ) m a d e a series of e x p e r i m e n t s with hens and o b served t h a t a meal of oats cleared t h e alimentary canal in 28 t o 29 hr. T h e birds were n o t starved before feeding and a second meal was

446

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ABSTRACT Five experiments were made to measure the time required for feed residues to clear the alimentary canal. The cumulative production of excreta dry matter was the primary criterion of measurement although attempts were made to adopt a stained particle technique. The latter was confounded by the production of metabolic and endogenous wastes. When full-fed adult roosters were taken off feed the residues within their alimentary canals were voided within 24 hr. Subsequent experiments involved placing known quantities of feed in the crops of starved roosters and measuring excreta production. Finely ground corn, wheat, oats, and barley (30 g) cleared the alimentary canal in 24 hr. The amount of wheat or wheat bran (10, 20, 30 g) placed in the crop affected the rate of passage but clearance was completed within 24 hr. A confounding factor was that the production of metabolic and endogenous waste decreased with the degree of starvation which was a function of feed input. Corrections based on the excreta production of negative control birds were not wholly satisfactory. The rate of excreta production was affected by the duration of starvation prior to the feeding of coarsely ground corn, soybean meal, and meat meal. The time of feeding also had a small effect. However, neither variable was of practical importance. It was found that while corn and soybean meal residues cleared the alimentary canal in 24 hr meat meal required about 30 hr. Alfalfa, fish meal, and wheat fed as pellets produced more excreta than when fed as meals. Pellets appeared to have the faster rate of passage through the alimentary canal. Both alfalfa and fish meal required more than 24 hr to pass through the birds.

RATE OF PASSAGE

Little of the available information on rate of passage is applicable to the present problem. In some experiments, the birds were given wet feed while in others they were full-fed before, during, and/or after administration of the test feed. Some of the markers were difficult to identify in the excreta while others may have had rates of passage which differed from those of the feeds to which they were added. In the experiment of Kaupp and Ivey (1923) in which lampblack was used as a marker some of the excreta voided in the later stages was coated with lampblack while the inside of the excreta was not marked. This suggested that the marker adhered to the intestinal mucosa and was picked up by other feed as it passed through the alimentary canal. An experiment preliminary to those of this report produced similar results when ferric oxide was the marker.

The experiments described in this report were conducted to obtain information on the rates of passage of feeds through adult roosters under conditions relevant to the TME and related bioassays. MATERIALS AND METHODS The experiments were made with adult, single comb, White Leghorn roosters of the Kentville Control Strain housed in individual wire cages in windowless rooms where they received 12 hr of light daily from 0600 to 1800 hr. Feed was available ad libitum between experiments and water was provided continuously. Experiment 1. The objective of the experiment was to determine if the withdrawal of feed for 24 hr, following a period of ad libitum intake, is sufficient to empty the alimentary canal of feed residues. Four diets were each fed to six birds for 90 hr. The feed was removed at 0800 hr and a plastic tray was placed beneath each bird. Excreta was collected quantitatively at 2, 4, 6, 8, 10, 22, 24, 26, 28, 30, 32, 34, 46, 48, 50, and 52 hr after feed removal. The excreta was transferred to plastic containers, frozen, dried at 80 C, and weighed. The calculated compositions of the four diets are presented in Table 1. The starter, grower, and layer diets were fed as mash while the turkey holding diet was in the form of pellets. Experiment 2. The experiment, which was designed to measure the time required for a single dose of feed to pass through the alimentary canal of a bird previously starved for 24 hr, comprised four treatments and four replications; the experimental unit was a single bird. Feed was removed from the birds at 0800 hr and 24 hr later each bird was weighed and force-fed the appropriate feedingstuff. The birds were then

TABLE 1. Calculated compositions of the diets fed in Experiment 1

Diet

Protein

lLayinghens 2 Chick starter 3 Chick grower 4 Turkey holding

15 18 13 15

Fat

Crude fiber

PhosCal- phocium rus

3.2 2.3 2.4 3.0

(%) 4.0 4.9 5.6 10.0

3.0 .74 .63 1.4

.65 .60 .56 1.00

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provided before all the oat residues were voided. It was observed that fluids passed more rapidly than solids and this caused misleading results when feeds stained with water soluble dyes were administered. Kaupp and Ivey (1923) used lampblack and dyes to measure the passage of feed through hens and observed their appearance in the excreta in about 4 hr with excreta returning to normal in about 72 hr. The dyes caused intestinal disturbances and constipation, while there was evidence that the rate of passage of lampblack differed from that of feed residues. Henry et al. (1933) used radiography to follow the passage of feed supplemented with barium sulphate through the alimentary canals of hens and reported that passage was completed in 16 to 26 hr depending on the level of intake. Jensen et al. (1962) followed the passage of a meal supplemented with chromic oxide through chicks fed ad libitum and found that peak excretion of the marker occurred 5 hr after the meal with small quantities being excreted 10 hr after withdrawal of the marked feed. Cherry and Siegel (1978) used ferric oxide as a marker and observed differences in the times of clearance from the alimentary canals of 7-week-old male and female chicks of two genotypes; the maximum time for clearance was about 22 hr. In addition to the foregoing, Hillerman et al. (1953) and Tuckey et al. (1958) have measured the times required for markers to appear in the excreta, while Keith et al. (1927), Heuser (1945), Hainan (1949), and Thornton et al. (1956) have recorded times of passage through specific sections of the alimentary canals of birds.

447

448

SIBBALD

Experiment 3. The experiment was designed to obtain additional information on the methodology of measuring the passage of feed through the alimentary canal and to investigate the effect of level of feed input on the excretion of feed residues by birds previously starved for 24 hr. A randomized block design was used with seven treatments and four replications. The treatments comprised placing in the crop 10, 20, or 30 g of either ground wheat or ground wheat bran, both supplemented with 1% by weight of stained particles; the feed was administered at 0800 hr. An additional four birds, which received no feed, served as negative controls for the measurement of metabolic and endogenous excretion. Excreta was collected quantitatively at 2 , 4 ,

6, 8, 10, 22, 24, 26, 28, 30, and 32 hr postfeeding. The excreta was frozen, dried, and weighed. The number of stained particles per g of dry excreta was measured for each bird for each collection period. Experiment 4. The experiment was designed to compare the rates of passage of coarsely ground corn, soybean meal (49% protein), and meat meal through the alimentary canals of adult roosters previously starved for either 24 or 36 hr. A secondary objective was to measure the effect of administering the feed either 10 or 4 hr before the onset of the 12 hr dark period. There were nine treatments and four replications. The design of the experiment is outlined in Table 2. On day 1 the feed was removed from 24 birds at 0800 hr and from an additional 12 birds at 1400 hr. On day 2 at 0800 hr, 12 of the birds starved for the 24 hr were selected at random and weighed. Each bird then received, by force-feeding, 30 g of corn, soybean meal, or meat meal. The treatments were repeated at 1400 hr using 12 birds starved for 30 hr and 12 birds starved for 24 hr. Excreta collection from individual birds began immediately after the initiation of the treatments and continued for 48 hr. At 2 hr intervals, except during periods of darkness, the excreta was transferred quantitatively to plastic containers and frozen. The excreta was dried at 80 C and weighed. Experiment 5. The purpose of the experiment was to study the rates of excreta production by birds fed alfalfa, fish meal, and wheat either ground or as pellets. Four birds were assigned to each treatment. The birds were starved for 24 hr and at 0800 hr were force-fed 30 g of the appropriate feedingstuff. Excreta was collected quantitatively at 2, 4, 6, 8, 10, 22, 24, 26, 28, 30, 32, 34, 46, 48, 50, and 52 hr post-feeding. The excreta was frozen, dried at 80 C and weighed.

RESULTS AND DISCUSSION

Experiment 1. The mean cumulative excretion of dry matter by each diet group (Y) is plotted against the time after feed removal (X) in Figure 1. The gaps in the lines represent the two 12-hr periods of darkness. The cumulative excreta output rose rapidly and almost linearly during the first 6 hr after feed removal with a difference between diet 4 (high fiber) and the other three diets being apparent at the time of the first excreta collec-

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placed in cages over plastic trays and the excreta voided was collected quantitatively at 2, 3, 4, 5, 6, 7, 8, 9, 10, 22, 23, 24, 26, 28, 30, and 32 hr after feeding. The excreta was transferred to plastic containers, frozen, dried at 80 C, and weighed. The feedingstuffs were finely ground corn, wheat, barley, and oats supplemented with 1% by weight of stained particles of the same feedingstuff. The birds received either 29 g of oats or 30 g of one of the other grains. The purpose of the stained particles was to serve as a marker for measurement of rate of passage by a modification of the procedure described by Balch (1950). Staining followed the procedure of Castle (1956). A 50 g subsample of the feedingstuff was mixed with 500 ml of a .025% aqueous solution of basic fuchsin, boiled for .5 hr, filtered, boiled with 500 ml of water for .5 hr, filtered, washed, and dried at 85 C. The resultant stained material was mixed with unstained ground grain from the same batch prior to feeding. The dry excreta was made into a slurry with water and washed onto a weighed piece of gauze stretched over an embroidery hoop. A stream of water was used to wash most of the excreta through the gauze. The number of stained particles remaining on the gauze was counted following which the gauze plus excreta particles was dried and weighed. The number of particles per gram of dry excreta was calculated for each bird for each collection period. By multiplying these values by the weight of excreta voided, it was possible to calculate the number of particles voided. For purposes of interpretation these data were expressed as cumulative percentages.

RATE OF PASSAGE

449

TABLE 2. Design of Experiment 4 Treatments Day

Time

1

0800 1400 0800 1400

2

a

FR a

FR

corn"

soy

FR

FR

FR

FR FR

soy

FR

FR

soy

meat

F R - feed removed.

tion, 2 hr after feed removal. The rate of excreta production diminished from 6 to 10 hr after feed removal and from 22 hr the cumulative production for each diet group approached linearity. From 10 to 52 hr the mean excreta

- •—

0

10

DIET DIET DIET DIET

1 2 3 4

20

outputs for the birds fed diets 1, 2, 3, and 4 were 7.3 ± .4, 6.4 ± .4, 6.2 ± . 3 , and 6.8 ± .2, respectively. An analysis of variance showed that these amounts were not significantly different (P>.05). The regressions of cumulative excretion of dry matter (Y) on the time after feed removal (X) were calculated for each diet using the mean values for 22 to 52 hr inclusive. The equations obtained were: Diet l . Y = 5.31 + .165X r = .998 at 9 df 2 . Y = 4.32 + .144X r = .998 at 9 df 3 . Y = 3.27 + .138X r = .997 at 9 df 4. Y = 10.99 + .142X r = .994 at 9 df The intercepts of the lines exhibit marked variation due to the type and/or amount of feed consumed but the regression coefficients are similar. To investigate these relationships further the individual regressions were calculated for each bird and the resulting coefficients were subjected to an analysis of variance. The differences between diet groups were not significant (P>.05). The absence of differences in the slopes of the regression lines implies that, irrespective of the diet, the birds were voiding excreta at a constant rate after the tenth hour following feed removal. It is postulated that the excreta was of metabolic and endogenous origin, because if feed residues were being voided the slopes of the lines should show pronounced differences.

30

40

50

60

TIME AFTER FEED REMOVAL (HR)

FIG. 1. Cumulative dry matter excretion, following the removal of feed, by birds which received four different diets.

The results of this experiment support the conclusion that the withdrawal of feed for 24 hr is sufficient to empty the alimentary canal of the adult rooster previously fed ad libitum. Experiment 2. The birds had a mean weight of 1.99 kg at the time for force-feeding. The

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bCorn — 30 g corn placed in crop. c Soy — 30 g soybean meal (49% protein) placed in crop. Meat — 30 g meat meal placed in crop.

SIBBALD

450

The cumulative percentage of stained particles appearing in the excreta is plotted against the time after feeding in Figure 3. The first appearance of stained particles in the excreta of

DARK PERIOD 1

_ . - • •

CORN WHEAT

corn fed birds varied from 3 to 6 hr after feeding, but the mean cumulative percentage did not exceed 1% until the sixth hour. Subsequently, excretion rose rapidly reaching 94% at 24 hr. For wheat fed birds, the initial appearance ranged from less than two up to the fifth hour with 98% being voided at 24 hr. For barley and oats all birds had voided stained particles by the third hour. At 24 hr after feeding the excretions were 91 and 97% for barley and oats, respectively. The method of Balch (1950) for measuring the rate of passage was not applied to the particle data because of the discontinuity of the curves caused by the 12 hr dark period. The lines in Figure 3 suggest that particles of stained oats and barley appeared before those of wheat and that those of corn were further delayed. However, it should be noted that oats and barley are less digestible than corn and that more particles were likely to survive passage through the alimentary canal to be counted. At the upper ends of the graphs the particles voided at 24 hr ranged from 91 to 98%. For all grains more than 99% of the particles were voided by 28 hr. Counting the colored particles in the excreta presented difficulties. It appeared that some particles lost color during passage and therefore a range of shades was detected on the gauzes. It was not certain that all stained particles were counted or that all counted particles were stained. A secondary problem was that the weight of excreta remaining on the gauze was small relative to the weights of both the gauze and the excreta voided. Small errors in counts or weights could have pronounced effects on

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FIG. 3. Cumulative excretion of stained particles by birds given a single feed of ground grain following 24 hr of starvation.

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differences between the four treatment groups were insignificant but the variation between birds within groups, as measured by the standard errors of the means, ranged from .02 to .13 kg for the corn and barley groups, respectively. The pattern of dry matter excretion by the four groups of birds is illustrated by Figure 2. The cumulative excretions by the corn and oat fed groups were distinctly different at the third hour and remained so throughout the experiment. The difference between the wheat and barley fed birds was not established until completion of the dark period at 22 hr after feeding. In the 2 hr following the dark period (22 to 24 hr) there was a rapid production of excreta by all groups which was probably caused by a period of relatively high activity. From 24 to 32 hr the mean weight of dry excreta per bird was 1.39, 1.31, 1.38, and 1.39 g for the corn, wheat, barley, and oat groups, respectively. The cumulative dry matter excretion for the 24 to 32 hr period (Y) was regressed on time after feeding (X) to produce individual equations for each bird on each diet. Analysis of variance of the regression coefficients revealed no significant differences (P>.05) between treatments. It is therefore reasonable to conclude that the excreta was of metabolic and endogenous origin.

RATE OF PASSAGE

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the particles per gram of excreta and the values calculated therefrom. While these problems are important, there is a biological reason for distrusting the apparent excretion patterns of Figure 3. The particles per gram of excreta on the gauze are counted and multiplied by the weight of excreta produced. It is assumed that the excreta is of feed origin or that the ratio of metabolic plus endogenous wastes to feed residues is constant. This is obviously incorrect. At 24 hr after feeding the excreta produced is largely metabolic and endogenous in origin (Fig. 2), but if a single stained particle is found on the counting gauze it assumes an inflated value in subsequent calculations. Balch (1950) did not encounter this problem because his animals were fed on a regular basis following the administration of the stained feed. The results of this experiment demonstrate that the residues of single doses of finely ground corn, wheat, barley, and oats, administered to roosters previously starved for 24 hr, are voided within 24 hr. Consequently, a 24 hr excreta collection period is adequate when these grains are subjected to the TME or similar bioassays. Measurement of excreta production by the stained particle procedure is unsatisfactory because the ratio of feed residues to metabolic plus endogenous wastes varies with the time after feeding. Experiment 3. The mean body weights of the birds within the seven treatment groups at the time of feeding ranged from 1.84 to 2.16 kg but the differences between groups were not significant (P>.05) (Table 3). By chance, the mean weights tended to increase with the amount of feed to be administered but regression analysis showed the trend to be non-significant (P>.05). Mean weight losses during the 32 hr after feeding ranged from 45 to 72 g per bird but again the differences were not significant. The weight of dry matter excreted over 32 hr increased with the amount of feed administered and was greater for the birds which received wheat bran than for those fed wheat (Table 4); this reflects the lower digestibility of the bran. An analysis of variance showed the treatment differences to be significant (P<.01). When the excreta dry matter output (Y) was regressed on the feed input (0 to 30 g) (X) correlation coefficients of .943 and .991, each at 14 degrees of freedom, were obtained for the wheat and bran fed birds, respectively. The regression equations

451

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TABLE 4. Summary of regression analyses of cumulative excreta output (Y) on time after feeding (X) for the 24 to 32 hr period inclusive3Level of feed input (g)

Wheat Mean coefficient Mean intercept Wheat bran Mean coefficient Mean intercept

10

20

30

.097 ± .005 .84 + .10

.114 ± .009 1.88 ± .40

.127 ± .008 3.70 + .14

.138 ± .014 4.47 ± .20

.097 ± .005 .84 ± .10

.131 ± .007 5.08 + .39

.136 ± .009 10.71 + .19

.173 ± .013 14.84 ± .44

Y = 3.935 + .169X Y = 3.875 + .505X

(wheat) (bran)

The intercepts (3.935 and 3.875) are estimates of the weight (g) of metabolic and endogenous excreta dry matter while the regression coefficients (.169 and .505) are estimates of the weight of feed residue voided (g) resulting from the administration of 1 g of wheat or wheat bran. The cumulative excretion of dry matter by the wheat fed birds is shown in Figure 4. At 4 hr after feeding, but not 2 hr, the fed birds produced more excreta than the negative controls indicating that the first feed residues were voided between 2 and 4 hr after feeding. The amount of excreta increased in a curvilinear manner, for each level of feed input, until 24 hr after feeding when the outputs became linear. The regression of cumulative excreta dry matter (Y) on the time after feeding (X) was calculated for each bird using the data for 24 to 32 hr, inclusive. The results are summarized in

DARK PERIOD WHEAT Og 10g 20g 30g

TIME AFTER FEEDING (HR)

FIG. 4. Cumulative excretion of dry matter by birds fed various amounts of wheat.

Table 4. The coefficients increased with the level of feed input; this was confirmed by a second regression analysis (P<.01). Similarly the intercepts increased with the feed input (P<.01). The differences between the intercepts were expected but the increases in the regression coefficients require explanation. It is probable that the amount of metabolic and endogenous excreta voided by a fed bird in a specific time period increased with the amount of feed administered. Sibbald (1976c) showed that the energy voided per unit of time by starved birds decreased with the duration of starvation. As a partial check of this explanation, the excreta voided per 2 hr period by the negative control birds (Y) was regressed on the time after feeding the birds (X) for the period 0 to 10 hr, inclusive. A correlation coefficient of —.729 at 18 degrees of freedom was obtained together with the equation: Y = .519 - . 0 3 0 X which indicates that the weight of metabolic plus endogenous dry matter voided decreased by .030 g/hr. This value cannot be applied directly to the data of Table 4 but it is of such magnitude as to support the hypothesis that differences in the regression coefficients therein were associated with differing levels of metabolic and endogenous excretion following inputs of increasing amounts of wheat. The cumulative excretion of dry matter by the birds fed wheat bran is shown in Figure 5. At 2 hr after feeding the birds which received bran produced more excreta than the negative controls which indicates that some feed residues had cleared the digestive tract within 2 hr. The birds which received 20 and 30 g of bran produced excreta at similar rates for the first

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Means with standard errors.

RATE OF PASSAGE

453

DARK PERIOD

WHEAT-TOTAL WHEAT-NET BRAN-TOTAL BRAN-NET

- lOg — • 20g • 30 g

T6

20

24 TIME AFTER FEEDING [HR)

FIG. 5. Cumulative excretion of dry matter by birds fed various amounts of wheat bran.

FIG. 6. Cumulative excretion of total and net particles by birds fed wheat and wheat bran.

eight h o u r s after which t h e rate decreased for t h e birds fed 2 0 g while it c o n t i n u e d at t h e same rate, for at least an additional 2 hr, for t h e birds fed 30 g. This raises t h e possibility t h a t there is a m a x i m u m rate of excretion of feed residues. T h e rate of excretion reached a minim u m level 2 4 hr after feeding after which cumulative excreta o u t p u t approached linearity irrespective of t h e level of bran input. T h e data for 2 4 t o 32 hr inclusive were analyzed in t h e same m a n n e r as t h e wheat d a t a . T h e results in Table 4 show t h a t t h e individual regression coefficients and intercepts increased with t h e a m o u n t of bran fed. In b o t h cases t h e increases were f o u n d t o be significant ( P < . 0 1 ) b y regression analysis. T h e " t o t a l " cumulative particle excretions were calculated as in Experiment 2. In a d d i t i o n , " n e t " values were calculated by subtracting from t h e weight of excreta dry m a t t e r t h e m e a n weight of excreta voided by t h e negative control birds during t h e same t i m e period. This correction is n o t entirely satisfactory because it fails t o m a k e allowance for t h e fact t h a t t h e a m o u n t of m e t a b o l i c plus e n d o g e n o u s w a s t e voided b y t h e negative controls was p r o b a b l y less t h a n t h a t voided b y t h e fed birds. Nevertheless, t h e exercise was w o r t h w h i l e because it illustrated t h a t t h e reasons p u t forward for distrusting t h e excretion p a t t e r n s of Figure 3 were valid.

t h e t o t a l values. For example, 10 hr after feeding, t h e percentage of wheat residues voided was 6 0 % b y t h e t o t a l d a t a and 7 8 % b y t h e net data. T h e differences for t h e w h e a t bran were n o t as p r o n o u n c e d b u t t h e y followed t h e same t r e n d . It is interesting t o n o t e t h a t t h e bran passed t h r o u g h t h e alimentary canal m o r e r a p idly t h a n t h e wheat b u t t h e times of final clearance were similar. T h e net particle d a t a are subject t o t h e error n o t e d above; nevertheless they reveal interesting t r e n d s . T h e m e a n n e t particle excretion curves for t h e t h r e e levels of w h e a t input are presented in Figure 7. T h e t i m e passage of feed residues increased with t h e level of feed i n p u t up t o 10 hr after feeding. After t h e dark period t h e rates of excretion were similar with t o t a l excretion being reached at a b o u t 28 h r after feeding.

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INPUT 10g 20g 30 g

100

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FIG. 7. Cumulative net excretion of stained particles by birds fed various amounts of wheat.

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Similar curves for wheat bran are presented in Figure 8. The rate of passage when 30 g was fed was slower than when 10 or 20 g were fed. After the dark period the rates of passage were similar and were completed at about 26 hr after feeding. Because of the errors associated with the correction from total to net values, it would be unwise to place great confidence in the times required for total passage; however, the relative rates of passage should be valid. The results of this experiment demonstrate that the rates of passage of wheat and wheat bran are affected by the level of feed input but the completion of the excretion of feed residues is essentially complete within 24 hr after feeding. The rate of metabolic plus endogenous waste production decreases with the duration of starvation which makes it difficult to estimate the proportion of the excreta which is of feed origin. Corrections based on the excreta production of negative control birds are helpful but not entirely satisfactory. The stained particle technique is not suitable for the accurate measurement of the rate of feed residue excretion by starved birds which receive a single input of feed. Experiment 4. Some of the mean values, with their standard errors, are presented in Table 5. Although the birds were selected randomly there were differences (P<.05) between treatments in mean body weight largely attributable to the difference between birds fed soybean meal and those fed meat meal (P<.01). The birds fed meat meal lost less weight than did those fed corn or soybean meal (P<.01), part of which difference may have been due to their smaller body size.

RATE OF PASSAGE

The time of feed administration had a significant (P<.01) effect on excreta production to 48 hr after feeding. Among the birds starved for 24 hr those fed at 0800 hr produced more excreta than did those fed at 1400 hr; this was consistent and independent of the type of feed. It seems reasonable to assume that all feed residues were voided within 48 hr; therefore the differences in excreta output were due to differences in metabolic and endogenous waste production. There is no satisfactory explanation for these differences but it is possible that because the birds fed at 1400 hr were housed in

the room where excreta collection was in progress they were disturbed and ate less feed during the last few hours prior to feed withdrawal, the start of the starvation period, and thus were in a more advanced state of starvation during the 48 hr collection period than were the birds fed at 0800 hr. As was mentioned earlier, the output of metabolic plus endogenous excreta tends to be reduced as starvation progresses. The birds starved for 36 hr tended to produce less excreta dry matter during the 48 hr after feeding than did the birds starved for 24 hr (P<.05). This is consistent with the foregoing hypothesis. The cumulative dry matter excretions are plotted against the time after feeding in Figures 9, 10, and 11. The gaps in the lines represent the 12 hr periods of darkness. The excretion of corn residues followed a similar pattern irrespective of the time of feeding following 24 hr of starvation (Fig. 9); however, the birds starved for 36 hr produced less excreta with the difference being noticeable within 20 hr after feeding. From 24 hr after feeding the production of excreta by the three corn groups appeared to approach linearity as it did in Experiment 2. During the first 4 hr after feeding, the excretion of soybean meal residues was greater for birds fed at 0800 hr than for those fed at 1400 hr irrespective of the length of the starvation period. At 16 hr after feeding, the birds starved for 24 hr had produced more excreta than those starved for 36 hr but while the difference persisted until the conclusion of the ex-

TABLE 6. Mean squares from analyses of variance of the cumulative dry matter excretion data of Experiment 4 Source of variation Treatments Feedingstuffs (A) Corn vs. soy + meat (B) Soy vs. meat (C) Times (D) 24-8 vs. 24-14 (E)a 24-8+ 24-14 vs. 36-14 (F)a AXD Remainder

DF

1 1

0 to 48 hr

0 to 24 hr

24 to 48 hr

158.4519** 629.4978** 1248.1673** 10.8273**

100.7926** 393.7268** 768.9735** 18.4802*

15.0354** 57.6717** 57.7454** 57.5980**

4.1130

.3042

2.7120**

27

1

3.7525**

1

1.6714* .7992

2.6652

1.0828

.3770

3.8983

2.3991

*P<.05. **P<.01. a 24-8, starved 24 hr fed at 8.00 hr; 24-14, starved 24 hr fed at 14.00 hr; 36-14, starved 36 hr fed at 14.00 hr.

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There were large differences between treatments in the cumulative excreta dry matter from 0 to 48, 0 to 24, and 24 to 48 hr after feeding (P<.01). Analyses of variance of these parameters are summarized in Table 6. During each period the birds fed corn produced less excreta than did those fed soybean meal or meat meal (P<.01). From 0 to 48 hr and from 24 to 48 hr the birds fed meat meal voided more dry matter than those fed soybean meal (P<.01), but from 0 to 24 hr the situation was reversed (P<.05). This suggests that the meat meal residues were voided more slowly than were those of the soybean meal. The production of excreta by the meat meal groups was more variable than that of the other groups as shown by the standard errors of Table 5. In particular, the group starved for 24 hr and then fed meat meal at 1400 hr included a bird whose rate of excreta production was exceedingly small during the first 24 hr after feeding.

455

456

SIBBALD STA

24 24 36

VEO

it

FED

MEAT MEAL STARVED 24 hr 24 hr 14:00 hr 36 hr 14:00 hr

JS*

1

8:00 hr 14:00 hr 14:00 hr

.—- T jrs

**'

-V

**~^

/ /

TIME AFTER FEEDING (HR)

FIG. 9. Cumulative excretion of dry matter by birds fed corn at two times of day and following two periods of starvation.

SOYBEAN MEAL STARVED

j

24 hf 36 hr

FED 8:00 hr 14:00 hr 14:00 hr

_=~^ / s

//

/* TIME AFTER FEEDING IHR)

FIG. 10. Cumulative excretion of dry matter by birds fed soybean meal at two times of day and following two periods of starvation.

rized in Table 7. It is noticeable that the regression coefficients and intercepts describing the excretion patterns of birds fed meat meal had much larger standard errors than did those describing the excretion patterns of the other groups. Analyses of variance of the regression coefficients and intercepts showed that the corn groups differed significantly (P<.01) from the soybean meal and the meat meal groups. Between the latter two groups the regression coefficients were different at the 1% level of probability, while the intercepts were also different but at a lower level of significance (P<.05). The time of feeding and the duration of the prior starvation period had variable effects upon the cumulative excretion by birds fed corn, soybean meal, and meat meal. However, in terms of the TME and similar bioassays the two variables are probably of little practical importance if the feedingstuffs under test are corn or soybean meal. In an earlier report (Sibbald, 1976c) the duration of the starvation period had little effect on TME values. Meat meal appeared to pass through the alimentary canal more slowly than the other two feedingstuffs and an excreta collection period of as much as 30 hr may be required to ensure that all feed residues have been voided. There was a large amount of variation between birds within the meat meal groups which tended to mask the excretion patterns. Whether such variation is normal with this feedingstuff remains to be determined. Experiment 5. Some mean values, with their standard errors, are presented in Table 8. Analysis of variance demonstrated that mean body weights at the time of feeding, and weight

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periment it tended to diminish. As with the corn groups, the accumulation of excreta dry matter appeared to be linear after 24 hr. During the first 4 hr the meat meal fed birds behaved in a similar manner to those fed soybean meal but subsequently there were marked differences. The birds starved for 24 hr and fed at 0800 hr had a similar excretion pattern to those starved for 36 hr, while the birds starved for 24 hr and fed at 1400 hr produced substantially less excreta, particularly during 22 to 28 hr after feeding. The 24 hr starvation 0800 hr feeding group achieved a linear rate of cumulative excretion at about 28 hr after feeding. Because of the interruption of the dark period, it is not certain when the other two groups reached a steady rate of excretion. The curves in Figures 9 to 11 suggest that all residues of corn and soybean meal were voided in 24 hr after feeding, but the residues of meat meal took longer to clear the alimentary tract. The cumulative dry matter excretion (Y) was regressed on the time after feeding (X) using data from individual birds for the 24 to 48 hr inclusive period. The results are summa-

TIME AFTER FEEDING (HR)

FIG. 11. Cumulative excretion of dry matter by birds fed meat meal at two times of day and following two periods of starvation.

Means with standard errors.

2.17 72 29.61 24.42 5.19

Pellets

.996 t .003

.992 ± .005

t .20 ± 6 ± .48 ± .62 ± .66

.995 ± .001

.106 ± .005 3.41 ± .35

36 14.00

.994 ± .003

.154+ .012 14.09 ± .19

24 8.00 36 14.00

.996 ± .002

.998 ± .000

.174 ± .016 .159 ± .010 13.37 + .41 12.36 ± .45

24 14.00

Soyb ean meal

Pellets 2.38 ± 78± 22.46 ± 16.17 ± 6.29 ±

Meal 2.18 + .14 88 + 11 29.08 + .26 23.73 + 1.21 5.35 ± .97 .13 19 .52 1.18 .77

Fish meal

6.88 ±

2.16 ± 65 + 21.86 ± 14.98 ± 1

Meal

TABLE 8. Summary of some mean values of Experiment 5 a

Alfalfa

.114 ± .007 3.88 ± .43

24 14.00

Corn

.124 ± .004 3.80 + .54

Wt/bird at feeding (kg) Wt loss 52 hr after feeding (g) Excreta dry matter to 5 2 hr (g) Excreta dry matter to 24 hr (g) Excreta dry matter 24—52 hr (g)

Mean coefficient ± SEM Mean intercept ± SEM Mean correlation coefficient ± SEM

Feedingstuff Duration of starvation (hr) 24 8.00 Time of feeding (hr)

TABLE 7. Summary of regression analyses of cumulative dry matter excretion (Y) on time for the 24 to 48 hr period inclusive

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458

SIBBALD

The data describing the amount of excreta voided from 24 to 52 hr after feeding are interesting. In Experiments 2 and 3 it was found that the residues of wheat were voided within 24 hr and that excreta produced subsequently was of metabolic and endogenous origin. If the same holds true for the present experiment, then the data of Table 8 clearly demonstrate that residues of alfalfa and fish meal were being voided more than 24 hr after feeding. Such a difference in rate of passage is of importance in any assay based on a 24 hr excreta collection period. The differences in the rates and amounts of excreta production are apparent from Figure 12. The rate of production of alfalfa residues was rapid with no consistent difference between the two forms. The fish meal pellets caused the production of excreta at a faster rate than the meal which, for the first 10 hr after feeding, had a rate similar to pelleted wheat. The wheat meal residues were voided most slowly and in the least quantities. As in earlier experiments the production of excreta by the wheat fed birds was linear following the first 24 hr after feeding. This con-

30 -

P e l l e t s - ; ; ALFALFA

r

20 -

Meal

Pellets

*~*

FISH MEAL

Meal

Pellets WHEAT 10 -

0 0

_..••"

V

A if

10

1 20

I 30

Meal

40

50

60

TIME AFTER FEEDING (HR)

FIG. 12. The cumulative excretion of dry matter by birds fed three feedingstuffs in two forms.

firms that wheat residues were voided within 24 hr after being placed in the crop. Excreta production by the birds fed pelleted fish meal did not achieve linearity until 28 to 30 hr after feeding, while linearity was delayed even longer for the birds fed meal. The behavior of the birds fed alfalfa was intermediate between that of the birds fed wheat and fish meal. Linearity was reached by birds fed alfalfa pellets in about 26 hr and by those fed meal in about 30 hr. There is no explanation of why the pelleted material passed through the alimentary canal more rapidly than the meal. On occasions we have found very finely ground feed to form a lump in the crop which was rather slow to disintegrate but no such lumps were noted in the present study. In Experiments 2, 3, and 4 it was found that all feed residues, except those of meat meal, cleared the alimentary canal within 24 hr of administration. In Experiment 5 the time of clearance of fish meal and alfalfa residues required a longer period of time. The fibrous nature of the alfalfa may have been important but ground oats (Experiment 2) and wheat bran (Experiment 3) did not appear to be delayed. Fish meal is rich in protein but it is unlikely that this delayed passage as soybean meal residues cleared the canal in 24 hr (Experiment 4). This is not conclusive as meat meal was also cleared slowly (Experiment 4). It is notable that fish meal, meat meal, and alfalfa contain relatively large amounts of mineral matter which may

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losses during the subsequent 52 hr period, did not differ between treatment groups (P>.05). There were large differences between treatment groups in the amount of excreta dry matter voided during the 52 hr after feeding. The fibrous alfalfa yielded more excreta than the high ash fish meal, which in turn produced more excreta than the wheat (P<.01). Somewhat more interesting is the finding that pelleted feed resulted in the production of more excreta than did the same feedingstuff fed as meal. This difference, though small, proved to be significant. A possible explanation was that the pellets contained more dry matter than the meal, but when this was checked the reverse was found to be true. The percentage of dry matter in pellets and meal were found to be 94.1 vs. 95.8, 93.5 vs. 95.4, and 89.8 vs. 92.2 for the alfalfa, fish meal, and wheat, respectively. Pelleting may have reduced the digestibility of the feedingstuffs but this is highly unlikely. It is more probable that the pelleted material passed through the intestinal tract faster than the meal, thus causing a greater output of metabolic and endogenous waste. When the data describing excreta matter production to 24 hr were analyzed the differences between the two forms of the feedingstuffs were not significant (P>.05).

RATE OF PASSAGE

ACKNOWLEDGMENTS T h e a u t h o r wishes t o t h a n k S. Tobin and R . Church for t h e i r capable technical assistance. K. Price of t h e Engineering and Statistical R e search Institute, Agriculture Canada, provided valuable advice regarding d a t a i n t e r p r e t a t i o n .

REFERENCES Balch, C. C , 1950. Factors affecting the utilization of of food by dairy cows. 1. The rate of passage of food through the digestive tract. Brit. J. Nutrition 4:361-388. Browne, T. G., 1922. Some observations on the digestive system of the fowl. J. Comp. Path. Therapeut. 35:12-32. Castle, E. J., 1956. The rate of passage of foodstuffs through the alimentary tract of the goat. 1. Studies on adult animals fed hay and concentrates. Brit. J. Nutr. 1 0 : 1 5 - 2 3 . Cherry, J. A., and P. B. Siegel, 1978. Selection for body weight at eight weeks of age. 15. Feed passage and intestinal size of normal and dwarf chicks. Poultry Sci. 57:336-340. Hainan, E. T., 1949. The architecture of the avian gut and tolerance of crude fiber. Brit. J. Nutrition 3: 245-253. Henry, K. M., A. J. Macdonald, and H. E. Magee,

1933. Observations on the functions of the alimentary canal in fowls. J. Exp. Biol. 1 0 : 1 5 3 - 1 7 1 . Heuser, G. F., 1945. The rate of passage of feed from the crop of the hen. Poultry Sci. 2 4 : 2 0 - 2 4 . Hillerman, J. P., F. H. Kratzer, and W. O. Wilson, 1953. Food passage through chickens and turkeys and some regulating factors. Poultry Sci. 32:332— 335. Jensen, L. S., L. H. Merrill, C. V. Reddy, and J. McGinnis, 1962. Observations on eating patterns and rate of food passage of birds fed pelleted and unpelleted diets. Poultry Sci. 41:1414-1419. Jones, J. D., and I. R. Sibbald, 1978. The true metabolizable energy values for poultry of fractions of rapeseed (B. napus cult. Tower). Poultry Sci. 57: (In press). Kaupp, B. F., and J. E. Ivey, 1923. Time required for food to pass through the intestinal tract of fowls. J. Agri. Res. 23:721-725. Keith, H. M., L. E. Card, and H. H. Mitchell, 1927. The rate of passage of food through the digestive tract of the hen. J. Agri. Res. 34:759-770. Kessler, J., and O. P. Thomas, 1978. An evaluation of the true metabolizable energy system. Page 18—21 in Proc. Maryland Nutr. Conf. Sibbald, I. R., 1976a. A bioassay for true metabolizable energy in feedingstuffs. Poultry Sci. 55:303— 308. Sibbald, I. R., 1976b. The true metabolizable energy values of several feedingstuffs measured with roosters, laying hens, turkeys and broiler hens. Poultry Sci. 55:1459-1463. Sibbald, I. R., 1976c. The effect of the duration of starvation of the assay bird on true metabolizable energy values. Poultry Sci. 55:1578-1579. Sibbald, I. R., 1977. The true metabolizable energy system of feed evaluation. Page 32—35 in Proc. Maryland Nutr. Conf. Sibbald, I. R., 1978. The effect of the duration of the time interval between assays on true metabolizable energy values measured with adult roosters. Poultry Sci. 57:455-460. Thornton, P. A., P. J. Schaible, and L. F. Wolterink, 1956. Intestinal transit and skeletal retention of radioactive strontium 9 ° -yttrium 9 ° in the chick. Poultry Sci. 35:1055-1060. Tuckey, R., B. E. March, and J. Biely, 1958. Diet and rate of food passage in the growing chick. Poultry Sci. 37:787-792.

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have been responsible for reducing t h e a p p a r e n t rate of passage. T h e form and c o m p o s i t i o n of t h e mineral m a y b e i m p o r t a n t because in Exp e r i m e n t 1 t h e r e was n o evidence of delayed clearance of t h e laying hen diet. There is need for greater understanding of those properties of feedingstuffs which affect their rate of passage t h r o u g h t h e alimentary canal. Until t h e required information b e c o m e s available it will b e necessary t o use caution in applying bioassays based o n a 2 4 h r excreta collection period. Evidence of a high level of variation a m o n g assay results m a y indicate a need t o extend t h e collection period.

459