Effect of creep feeding on the incidence, duration and severity of post-weaning diarrhoea in pigs

Research in Veterinary Science 1990, 49, 223-228

Effect of creep feeding on the incidence, duration and severity of post-weaning diarrhoea in pigs D. KEL~Y*, Department of Food and Agricultural Chemistry, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5TX, J. J. O'BRIEN, Veterinary Research Laboratory, Stoney Road, Stormont, Belfast BT4 3SD, K. J. McCRACKEN, Department of Food and Agricultural Chemistry, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX and Food and Agricultural Chemistry Research Division, Department of Agriculture for Northern Ireland, Newforge Lane, Belfast BT95PX

The effect of creep feeding on the response of pigs weaned at two or three weeks old to infection with an enteropathogenic strain of Escherichia coli (0149; K91[B], K88 a, c [LD was studied in two separate experiments. Gastric intubation was adopted to regulate the intake of creep feed during the sucking period. Animals were given the enteropathogenic strain either before weaning or at weaning and the course and outcome of the infection followed bacteriologically and clinically. The response of the animals to the infection varied considerably in accord with recent reports of multiple phenotypes (to K88 + ve organisms) among pigs but consumption of creep feed before weaning did not significantly affect the prevalence, duration or severity of the diarrhoea ind uced experimentally by the organism. Hence reputed immunological responses mounted against dietary antigens did not predispose to or protect against this infection.

structure and function caused by the introduction of weaner diets. This suggestion was supported further by the observation that feeding creep before weaning (presumably 'tolerising' doses) avoided the xylose malabsorption observed in abruptly weaned pigs five days after weaning (Miller et aI1985). However, Kelly (1985), who investigated the effects of different levels of creep intake on gut morphology and function, could not demonstrate any effect of creep feeding on normal gut ontogeny. Hampson et al (1988) compared animals which had been fed small quantities of creep feed with abruptly weaned pigs and their results corroborate those of Kelly (1985) and of Kelly et al (1986, 1989). In view of this conflicting evidence on the effect of pre-weaning treatment on gut development in the

OUTBREAKS of Escherichia coli enteritis frequently occur in pigs immediately after weaning. Host predisposition is considered to be of major importance in initiating a sudden proliferation of enteropathogenic strains of E coli and hence in precipitating diarrhoea. The underlying factors which have been implicated include inflammatory metabolites of bacterial origin (Kenworthy 1976), immune-mediated damage to the small intestine (Miller et al 1983) and damage mediated by rotavirus (Leece et al 1983). Considerable interest has been focused on the role of dietary antigens since Miller .et al (1984a, 1985) reported that 'adequate intake of creep feed' before weaning protected pigs against post-weaning diarrhoea and postulated that the 'adequate' intake served to render, animals tolerant to dietary antigens, thereby reducing the damaging effect ~o the intestinal

Fat-filled skim-milk powder Flaked maize Maize meal Ground wheat Fish meal (680"g CP kg - 1) Soya 50 (480 9 CP kg -1) Sucrose Dicalcium phosphate Sodium chloride Trace minerals/vitamins *

340 255 64 100 100 65 50 20 3 3

Crude protein (N x 6· 25) (g kg -1) Fat (g kg- 1 ) Ash (g kg- 1 ) Crude fibre (g kg - 1 ) Calcium (g kg - 1) Phosphorus (g kg - 1) Sodium chloride (g kg - 1) Gross energy (MJ kg - 1)

237 109

·Present address: Rowett Research Institute, Bucksburn, Aberdeen AB29SB

TABLE 1: Composition Ig kg- 1 1and analysis (kg- 1 OMI of diet fed

67

11·3 13'1 8·8 14·0

19-5

* The trace minerals/vitamins mixture supplied (mg kg -1): iron , 20, zinc 65, copper 35, manganese 25, iodine 2, cobalt 1-, selenium O· 1, ascorbic acid 50, choline chloride 100, nicotinic acid 10, calcium pantothenate 8, riboflavin 4, menadione 4, pyridoxine hydrochloride 3, thiamine hydrochloride 1, retinol 12, o-tocophervl acetate 4, cholecalciferol 0 -035, cyanocobalamin 0 - 001

223

D. Kelly, J. J. O'Brien, K. J. McCracken

224

in individual metabolism cages in a controlled environment room (29°C, relative humidity 50 per cent) and were fed pelleted diet (Table 1) to appetite. Score Daily feed consumption and weight gain were 30-40 o Normal Nil 1 25-30 Soft Slight recorded during the post..weaning period and the 2 20-25 Grey fluid Moderate prevalence and duration of diarrhoea were noted. The 3 Yellow fluid <20 Severe severity of the diarrhoea was assessed visually and recorded daily on a scale of 0 to 3. Samples of fresh faeces were oven..dried at 100°C to constant weight each day and the faecal dry matter calculated. The post-weaning period, it was decided to test further the estimates for faecal dry matter were considered in 'hypersensitivity' hypothesis by infecting with E coli. conjunction with the visual appearance of the faeces Intake of creep feed was controlled by gastric to assist in evaluating severity (Table 2). Rectal swabs intubation (Kelly et al 1984) and a low-dose E coli were taken daily for assessment of the presence of the challenge, similar to that used successfully by Miller et pathogenic strain up to 12 days after weaning, at al (1984a), was imposed. Post..weaning E coli pro .. which stage the experiment was terminated. liferation, incidence of diarrhoea and pig per.. formance was monitored for up to two weeks afterwards .' Experiment 2

TABLI: 2: Scoring system for severity of diarrhoea Appearance of faeces

Severity of diarrhoea

Faecal solids (%w!v)

Forty-five piglets were selected from five litters at seven days old and randomised on a litter and weight basis to one of three treatment groups. Two groups were given no creep feed before weaning. The third group (T) was tube-fed increasing amounts of diet (Table I) from seven to 20 days old starting with 20 g per day and rising to 60 g per day so that each pig received a total of 600 g creep feed (high creep level). All animals were weaned on day 21. On the same day one group of the abruptly weaned pigs (positive control, cr) and the group which had received creep feed were exposed to an oral dose of 106 enteropathogenic E coli. The remaining 15 animals were not infected (negative control, ex) and were maintained under similar conditions to those of the two challenged groups, but in isolation. Subsequent animal handling was as described for experiment 1. In addition, the abundance of haemolytic, K88 positive E coli (see below) was categorised as pure/almost pure, about 50 per cent, few or absent. These categories were assigned scores of 3, 2, 1, 0, respec.. tively, and total scores were calculated for each pig. The results were analysed statistically by the variance method.

Materials and methods

Experiment 1 Four farrowings were supervised and the piglets . withheld from the sow until the last pig was born to equalise sucking opportunities. At seven days old eight pigs per litter were dosed orally with 103 organisms of an enteropathogenic strain of E coli (0149; K91 [B], K88 a, c [L)), very large or very small pigs being excluded. At eight days old 24 piglets (six per litter) were randomised on a litter and weight basis to one of three treatments; zero (abruptly weaned), low creep (10 g diet [Table 1] per day for six days) given in one single feed each morning or high creep (60, 80, 90, 100, 110, 110 g diet [Table I] on days 8 to 13, respectively) given in three equal daily feeds by gastric intubation. The two spare pigs were also allocated to the zero treatment. Two of the high.. creep pigs died j ust before weaning and two 0 f the zero creep spares were abruptly weaned to use the cages in the weaner accommodation thus giving 10, eight and six pigs, respectively, in the zero, low and high creep groups. The pigs were weaned at 14 days old, placed

TABLE 3: Weight gain during the pre- and post-weaning period of piglets fed zero, low or high creep Zero Pre-weaning weight gain g d- 1

85·7 (10)

Post-weaning weight gain 9 d- 1

116

P<0·05

NS

Not significant

(10)

Creep (number of pigs) Low High

78·6

114·3

(8)

(6)

108

75

(6)

(3)

SEM

Statistical significance

7·1 10·3

NS

Creep feeding and post-weaning diarrhoea in pigs TABLE 4: Prevalence and severity of diarrhoea in pigs fed zero, low or high creep before weaning at 14 days and infected with 10 3 enteropathogenic E coli (ranges)

Prevalence Mean duration (days) Score* Mortality

Zero creep

Low creep

High creep

S/10 2-8 (0-6) 3-5 (0-11)

7/8 4-0 (0-7) 6-75 (0-15) 2

6/6 3-5 (1-7) 6·83 (2-16) 3

0

* Total period score of severity of diarrhoea based on scale of 0.1,2 or 3 (Table 1)

E coli enumeration and serotyping The enteropathogenic strain of E coli used in the experiments was supplied by the Northern Ireland Veterinary Research Laboratory and had been isolated from a field case of piglet enteritis. The haemolytic capacity of bacteria isolated from rectal swabs was assessed on 7 per cent bovine blood agar incubated at 37°C for 24 hours. A zone of haemolysis of I mm surrounding separate colonies was regarded as positive. Five haemolytic colonies were selected randomly and grown on blood agar plates which were incubated at 37°C overnight. The K antigens of E coli isolates were tested by slide agglutination with antisera prepared in rabbits (SoderIind 1971). Du ring outbreaks of diarrhoea the total population of haemolytic E coli in fresh faeces was ascertained on 7 per cent bovine blood agar by viable counts (Miles et al 1938).

Results

Experiment 1 Feeding the high level of creep significantly increased weight gain (P<0·05) compared with the zero or low groups during the pre-weaning period (Table 3). There was no pre-weaning treatment effect on feed consumption or weight gain during the postweaning period. No haemolytic E coli were detected in faecal swabs obtained before weaning butt during the postweaning period t the experimental strain was isolated in pure culture from all but one animal. The mean numbers of days before the onset of diarrhoea were 5 · 3t 6· 0 and 6· 0 for the zero t low and high creep groups, respectively. Haemolytic E coli were usually isolated from pigs at the stage at which clinical signs were apparent. The aerobic flora of faecal samples collected at the onset of diarrhoea and during the diarrhoea were invariably dominated by the experimental strain, at levels of 108 to 1010 organisms g-t of

225

fresh faeces. The prevalence of diarrhoea was 80 t 87 and 100 pet cent, respectively, for the zero, low and high creep groups (Table 4). In pigs suffering from a slight to moderate infection (Table 2)t feed consumption decreased by 25 to 30 per cent on the day before, or on the first day oft scouring. Appetite usually recovered two to three days later. In severely affected pigs, feed consumption also fell initially by about a third. Faecal appearance changed from a grey to yellowish fluid, and the moisture content rose to approximately 90 per cent (Table 2). At this stage, feed consumption was approximately 10 to 30 per cent of that before the onset of diarrhoea and these pigs became dehydrated and eventually moribund. The severity of disease was different in the three groups. Using scour score and mortality as indices, the piglets which had received the high or low level of creep feed suffered more severely than those given no creep (Table 4). Mortality was 50 per cent in the high-creep group and 25 per cent in the low-creep group, whereas all the abruptly weaned pigs survived and recovered from the infection.

Experiment 2 As in experiment I t there was no significant effect of creep feeding on either the weight gain or the feed intake of animals during the post-weaning period (Table 5). The strain used to infect the CP and T pigs was not recovered from the animals which were not exposed to infection and kept in isolation (eN) (Table 6). Weight gain tended to be greater than for the infected pigs (Table 5) but not significantly so. There was no significant effect of creep feeding on the number of days during which the pathogenic E coli was recovered from the faeces or on the number of days during which it was excreted in pure culture (Table 6). The response to the infection was extremely variable within both treatments and even between individual littermates. The bacterial scores ranged from 0 to 15 for cp and 0 to 20 for T pigs, the mean values not differing significantly. Fig 1 illustrates the

TABLE 5: Feed intake and weight gain (g d - ,) during the period after weaning in piglets abruptly weaned (eN, 15). abruptly weaned and infected experimentally with enteropathogenic E coIl (CP. 15) or fed a high level of creep and infected with E coli (T. 15) After weaning

eN

CP

T

SEM

Weight gain Feed intake

20S 215

195 208

186 214

14·6

NS Not significant

18·6

Statistical significance NS NS

226

D. Kelly, J. J. O'Brien, K. J. McCracken TABLE 6: Comparison of enteropathogenic E coli excretion in three week weaned pigs: abruptly weaned (CN, 15), abruptly weaned and infected experimentally with enteropathogenic E coli (cp, , 5) or fed a high level of creep and infected with f coli (T, , 5) CN* Average E coli scoret

0

Average number of days E coli excreted in faeces

0

Average number of days pure

0

E coli excreted in the faeces

CP

T

SEM

Statistical significance

7·0

7·9 (0-20)

1·87

NS

3'8

0·78

NS

i-a

0·51

NS

fO-15)

3·8

(0-8)

1·3 (0-4)

(0-8)

(0-5)

CN group not included in statistical analysis

E coli score for period based on daily score of 0, 1, 2 or 3 for zero, few, about 50 per cent or

t

pure/almost pure culture of experimental strain NS Not significant

pattern of excretion of haemolytic E coli in groups cr and T. The first evidence of infection for both groups was on day 2 after weaning and excretion of the pathogen was minimal by day 9. The prevalence of infection peaked during days 5 and 6 after weaning. The duration and severity of diarrhoea in the animals was not significantly affected by the pre-weaning ,treatment (Table 7), but the mean values were significantly higher (P < O·05) than for the control group.

Discussion The results from experiment 1 indicated that the mean duration and severity of infection (as indicated from the group mortality and severity score) were

15

en 15

E

CP T

CP T

CP T

CP T

CP T

CP T

CP T

CP T E coli score

13

Do

11

lIJ2

.~

9

.8E

7

....o

CP T

greatest in those pigs fed creep before weaning, suggesting that some benefit might have been gained by abrupt weaning. Similar observations were reported from' a field investigation of creep feeding versus abrupt weaning (Miller et a11984b) and in fact provided the rationale for the selection of the treatment groups for experiment 2. The average period before the onset of diarrhoea was 5· 5 days in experiment 1. This is similar to the results of Miller et al (1983, 1984a) and of Hampson et al (1988) who relied on"the 'natural' infection or infection with a low dose of E coli in weaned pigs at three weeks. The experimental strain was consistently isolated from the faeces during bouts of diarrhoea, the total counts being in the range of 108 to 1010 organisms g-I of fresh faeces. Similar numbers have

~1

113

::::J

Z

5 3

2

3

4 5 6 Days after weaning

7

8

9

FIG 1: Extent of faecal excretion of pathogenic E coli after experimental infection. Pigs sampled from day 1 to 9 after weaning. 0 Zero; 1 Few; 2 50 per cent pure; 3 Almost virtually pure CP Positive control pigs; abruptly weaned and infected with enteropathogenic E coli T Pigs tube-fed increasing amounts of creep feed up to 600 9 in total

227

Creep feeding and post-weaning diarrhoea in pigs TABLE 7: Comparison of the prevalence and severity of diarrhoea in three week weaned pigs: abruptly weaned (eN, 15) abruptly weaned and infected with enteropathogenicE coli (CPr 15) or fed a high level of creep and infected with E coli (T, 15) (ranges given in brackets) CN

CP

T

Incidence

6/15

13/15

12/15

Mean duration (d)

1·41

3'27

Mean score Mortality

3'93

0·614

7'4

1·31

(0-5)

(0-7)

(0-6)

~'33

6·8 (0-15)

(0-21)

0

0

(0-9) 0

SEM

Statistical significance

Total period score of severity of diarrhoea based on daily scale of 0, 1, 2 or 3 (Table 1) * P<0·05

been reported by Smith and Linggood (1971). Shedding did not correlate with severity of diarrhoea. This finding supports the observations of Sarmiento et al (1988), who concluded that faecal shedding was not a reliable indicator of colonisation of the small intestine because of the uncertainty regarding the proliferative or pathogenic activity of these bacteria during transit in the small intestine and in the hind gut. The fact that no haemolytic E coli were detected in the faeces before weaning, but that consistent proliferation and associated scour occurred after weaning, is of considerable practical importance. This indicates that a low-level, subclinical infection with a bacterial pathogen before weaning can manifest itself as a clinical problem at a later date and underlines the need for good hygiene in the farrowing house. The onset and severity of the diarrhoea was not alleviated by prior exposure to a high level 0 f creep feed. This contrasts with the report of Miller et al (1985) that pigs encouraged to consume a tolerising dose of creep feed did not show the xylose malabsorption associated with other weaning regimes or succumb to post-weaning diarrhoea (Miller et al 1984a). The failure to demonstrate prophylaxis against E coli infection by high pre-weaning intakes at either two or three weeks old (Kelly 1985, Kelly et al 1986) and the absence of a pre-weaning treatment effect on the morphology and function of the gut (Kelly et al 1986, 1989) are inconsistent with the hypothesis of delayed hypersensitivity. The present results support those of Hampson et al (1988), who compared abruptly weaned pigs with animals fed low levels of creep feed (primed) and observed no differences in the susceptibility or severity of diarrhoea between the two groups. An important feature of the current. results was the variation observed in the response of pigs to the E coli. It is unlikely that the variability in response was due to inadequacy of the dosing procedure, since infected animals were housed in the same room and

were routinely handled by the same personnel, thus offering ample opportunity for continued cross infection. The susceptibility of pigs to infection with pathogenic E coli is genetically determined. Sellwood et al (1975) described two phenotypes, one possessing a receptor for the K88 antigen and another which lacks the receptor and is consequently resistant to infection. However, recent information indicates the existence of at least five phenotypes, comprising one 'non-adhesive' phenotype and four 'adhesive' types (Bijisma et al 1982), two of which will bind K88 a, c antigen. Intermediate phenotypes may also occur as a result of epistatic gene modification (Bijisma and Bouw 1987). The existence of multiple phenotypes within litters to K88 a, c is compatible with the variable response to infection observed in this study and by other workers (Sojka et al 1960, Miniats and Roe 1968, Sarmiento et a11988). A consistent observation which cannot be overlooked is the increased susceptibility of pigs to bacterial and toxin-mediated infections at weaning (Miller et al 1984a). The removal of lactogenic immunity is possibly a contributing factor (Blood et al 1979) to this susceptibility. It is increasingly clear that the developmental process in the gut is accompanied by subtle changes in the microvillar membranes which may influence disease susceptibility. The maturity of the enterocyte influences its binding characteristics for lectins and this glycosylation shift might increase binding of bacteria to the mucosal surface (Etzler and Branstrator 1979). Pang et al (1987) and King and Kelly (1990) have provided conclusive evidence indicating that modification of carbohydrate moieties of the microvillar membrane occurs during development in the rat and pig. This may be reflected in the heightened susceptibility to infection (precocious shedding of E coli in the faeces) observed with some of the animals weaned at three weeks old in the current study, perhaps involving changes in the expression and maturation of bacterial receptor sites on the mucosal surfaces. The susceptibility of rabbit intestine to colonisation by E coli is temporally related

228

D. Kelly, J. J. O'Brien, K. J. McCracken

to the appearance of receptors (Boedeker and Cheney 1984). It is, therefore, suggested that the process of weaning encourages the expression of receptors including those which are recognised by enteric pathogens. This possibility, considered in conjunction with physiological immaturity of the immune system of the young pig at two to three weeks old, may explain the high incidence of enteric infection associated with the practice of early weaning.

Acknowledgements D.K. was supported by a CAST Award from the Department of Education, Northern Ireland and John Thompson and Sons Ltd. The authors are indebted to Mr A. McAllister, Mr J. Lilley and Mr P. Cush for their expert technical assistance and to Dr D. J. Kilpatrick for statistical advice.

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KELLY, D. (1985) PhD thesis, The Queen's University of Belfast KELLY, D., GREENE, I., O'BRIEN, I. J. & McCRACKEN, K. I. (1984) 8th International Pig Veterinary Society Proceedings, Ghent. p 317 KELLY, D., GREENE, J. & McCRACKEN, K. I. (1986) Pro~ ceedings of the 6th International Conference on Production Diseases in Farm Animals. p 194 KELLY, D., GREENE, J. & McCRACKEN, K. J. (1990) Research in Veterinary Science 48, 350-356 KING, T. P. & KELLY, D. (1990) Proceedings of the Nutrition Society 49, 142A LECCE, I. G., CLARE, D. A., BALSBAUGH, R. K. & COLLIER, D. N. (1983) Journal oj Clinical Microbiology 17, 689-695 MILES, A. A., MISRA, S. S. & IRWIN, J. D. (1938) Journal of Hygiene 38, 732-749 MILLER, B. G., NEWBY, T. J., STOKES, C. R. & BOURNE, F. J. (1984a) Research in Veterinary Science 36, 187-193 MILLER, B. G., NEWBY, T. J., STOKES, C. R. & BOURNE, F. I. (l984b) Veterinary Record 114,296-297 MILLER, B. G., NEWBY, T. I., STOKES, C. R. & BOURNE, F. I. (1983) Annales de Recherches Veterinaires 14, 487-492 MILLER, B. G., PHILLIPS, A., NEWBY, T. J., STOKES, C. R. & BOURNE, F. J. (1985) Proceedings of the Third International Seminar on Digestive Physiology in the Pig. pp 65-68 MINIATS, D. P. & ROE, C. K. (1968) Canadian Veterinary JournaI9,210-217 PANG, K. Y., BREESON, I. L. & WALKER, W. A. (1987) American Journal of Physiology 252, G685-G691 SARMIENTO, J. I., CASEY, T. A. & MOON, H,. W. (1988) American Journal of Veterinary Research 49, 1154-1159 SELLWOOD, R., GIBBONS, R. A., lONES, G. W. & RUTTER, J. M. (1975) Journal of Medical Microbiology 8,405-411 SMITH, H. W. & LINGGOOD,. M. A. (1971) Journal of Medical Microbiology 4,467-485 SODERLIND, O. (1971) Zentralblatt fur Veterinarmedizin Reihe 18,569-590 SOJKA, W. I., LLOYD, M. K. & SWEENEY, E. J. (1960) Research in Veterinary Science 1, 17-27

Received June 26, /989 Accepted March /5, /990