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Early postnatal amylolysis in the gastrointestinal tract of turkey poults Meleagris gallopavo
Camp. Biochem. Physfol. Vol. 107A, No. Printed in Great Britain
1, PP. 221-226,
1994
03OC-9629/94 $6.00 + 0.00
0 1993Pergamon Press Ltd
Early postnatal amylolysis in the gastrointestinal tract of turkey poults Meleagris gaZZopavo Y. Pinchasov and Y. Noy Department of Animal Science, Faculty of Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76-100, Israel The developmental pattern of the gastrointestinal tract (GIT) and its amylolytic capability were examined during the 10 days post-batch in turkey poults. Tbe digestive capacity of the GIT increased to a peak value at 4 days of age and declined thereafter. Substantial amylolysis was evident in tbe crop, whereas an insiguificant amount of starch was hydrolyzed in tbe ventriculus and only residual amounts could be detected in the small intestine or cecum. Tbe results indicate that despite a slight limitation in the secretory rate of pancreatic amylase, newly batched poults are capable of high amylolylic activity. Key words: Turkey (Meleugris gallopavo); Amylolysis; Early growth; Gastrointestinal
development;
Pancreatic amylase; Poults; Starch. Comp. Biochem. Physiol. 107A, 221-226,
1994.
Introduction The rapid transition from yolk-based embryonic nutrition to exogenous dietary-based neonatal nutrition stimulates drastic changes in the digestive system of newly hatched birds. The shift from yolk-originated lipid to dietary carbohydrate as an energy source has been reported to alter the birds’ glucogenic metabolism (Moran, 1990; Donaldson et al., 1992; Warriss et al., 1992) the GIT and its digestive enzymes (Krogdahl and Sell, 1989; Nitsan et al., 1991; Sell et al., 1991; Tarvid, 1992), and the metabolizability of dietary energy and lipid absorption (Murakami et al., 1992). Although the fowl’s ability to release amylase has been stated to be sufficient (Moran, 1982), a decrease in amylase activity has been reported in post-hatch birds (Nitsan et al., 1991; Sell et al., 1991). The low capability to utilize dietary nutrients immediately after hatch is presumed to be, in part, a consequence of incomplete development of the digestive system. A determination
Correspondence ro: Y. Pinchasov, Department of Animal Science, Faculty of Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76-100, Israel. Fax: 972-8-465763. Received 8 March 1993; accepted 7 April 1993.
of amylolysis capability, with regards to amylase activity in various sites of the GIT, is essential to assessing starch hydrolysis during the critical post-hatch period. The purpose of the present study was to examine the developmental pattern of the GIT, focusing on its amylolytic capability, during the early posthatch period in turkey poults (Meleugris gallopavo).
Materials and Methods Experimental animals
One hundred and twenty post-hatched male turkey poults (Meleugris gdopuvo) of the Nicholas strain were weighed, wing-banded and moved to an individual battery brooder, located in a temperature- and ventilation-controlled room. They were brooded in groups of three birds/cage for the first three days, then in individual cages to day 10 of the experimental period. Poults were provided with a commercial starter turkey diet, containing 2800 kcal of ME and 280 g CP/kg diet, and free access to food and water. Feed intake was measured per group to 3 days of age, and individually thereafter. Body weight was monitored individually throughout the experiment. Necropsy was
221
222
Y. Pinchasov and Y. Noy
carried out five times during the experiment, on 20 to 24 birds each. The birds were killed by cervical dislocation, the abdominal cavity was opened and residual yolk, liver and pancreas were removed, weighed and frozen (-20°C). The GIT segments were cut and the crop, ventriculus, upper (duodenum) and lower (iejunum + ileum) small intestine (SI), and cecum were weighed with and without contents. The removed ingesta was kept for analysis ( - 20°C). The pH of the ingesta was measured for each segment. Pancreatic alpha-amylase assay The activity of pancreatic alpha-amylase (EC 3.2.1.1) was determined using a modification of Bernfeld’s (1955) procedure. The pancreas was homogenized in 50 volumes of ice-cold deionized water with an Ultra-Turrax homogenizer (setting 5, 30 set). The homogenate was centrifuged at 12,000 g for 15 min (0-4C) and an aliquot of the supernatant was used for enzyme assay. Starch solution (1 g/l00 ml, Merck) gelatinized in 20 mM buffered phosphate solution (BPS) (pH 6.9) containing 10mM NaCl, was used as a substrate. One ml of this solution was added to duplicate supernatant samples and incubated for 3 min at 37°C. For each assay, a soluble starch solution (0 to 8 mg/ml, Merck) was hydrolyzed with alpha-amylase from Aspergillus oryzae (16 U/ml, Sigma) as a standard.
250
1
I
I
I
Statistical analysis Analysis of variance was carried out using the General Linear Model (GLM) procedure of base SAS@ software (SAS Institute, 1985). Duncan’s multiple range test was used to compare differences among segment or and/or age means.
150
/
100
0
Starch and sugar content in diet and GIT Starch levels in the diet and in GIT thyme were determined using a modified method based on that described by Annison (1990). Portions of GIT thyme sampled from each segment were lyophilized and mashed. Triplicate samples (10-20 mg DM) were weighed into screw-cap tubes, mixed with 10 ml of the BPS, and incubated with frequent agitation for 120 min at 100°C. After cooling, alpha-amylase (16 U, Aspergillus oryzae) was added to each tube and incubated for 120 min at 37°C. Each segment was tested in duplicate samples, and in one blank replicate assayed without the added amylase. A soluble starch solution was used as a standard for each assay. The increase in reducing power was measured with DNS reagent at 550 nm in a microplate reader as described above. The amount of reducing sugars was estimated as equal to amount of glucose liberated during starch digestion with alpha-amylase.
T
200
50
One unit (U) of amylase activity was defined as the hydrolysis of 1 mg starch per 3 min at 37°C. An increase in reducing power following hydrolysis measured by dinitrosalicylic acid (DNS) reagent was used to determine the amylolytic activity. After the addition of DNS, reaction tubes were heated for 5 min in boiling water, cooled to room temperature and absorbance was measured at 500 nm. Calorimetric determination was carried out using a computerized microplate reader (Bio-Tek Instruments, EL309).
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I
1
I
0
2
4
6
8
10
12
Result!3
40
30
20
10
0 0
2
4
AGE
6
6
lc
12
(days)
Fig. 1. Body weights (0) and daily feed intake (0) during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of 20-30 birds.
Body weight and daily feed intake increased in a parallel manner during the 10 days posthatch (Fig. 1). The relative weights of the GIT segments increased with age after hatching, reaching peak values at 4 days of age and declining thereafter (Fig. 2). GIT content, however, displayed a different pattern with age, in that a basal value was observed in all segments until 1 day of age, followed by a marked increase (Fig. 2). Peak values of the GIT’s relative contents tended to decrease to 10 days of age, except for duodenal content. Acidic pHs were observed in the GIT segments, especially in the ventriculus, with the
Post-hatch amylolysis development in turkey poults
223
Fig. 2. Gastrointestinal tract (GIT) weights (left) and GIT contents weights (right) during the early post-hatch period in male turkey poults. Lower SI = jejunum + ileum; each symbol represents mean and SE of 20-24 birds.
exception of the lower small intestine which was slightly basic (Fig. 3). pH values increased with age after hatching in the ventriculus and small intestine to 2 days of age and declined thereafter. Only a slight change in pH was observed in the crop with age. A neutral pH was measured in the cecum immediately after hatching, but decreased significantly (P < 0.05) to pH 6 after 1 day, then increased slightly with age for the rest of the IO-day experiment. Starch level in the crop ingesta was significantly (P < 0.05) lower, by about one-third that found in the ventriculus (Fig. 4) or diet (30 to 32 g/100 g DM), while only a residual amount of starch could be detected in the small intestine and cecum throughout the experimental period (Fig. 4). The level of starch in the crop was maximal at 2 days of age (21 g/100 g DM ingesta) and declined significantly (P < 0.05) to 10 days. In ventriculus, starch levels increased 4 days post-hatch, ranging between 31 and 32 g/100 g DM ingesta, thereafter. The amount
of reducing sugars appearing in the crop following the hydrolysis of starch increased after hatching from 10 to approximately 13 g/100 g DM (Fig. 4). In the ventriculus, a peak was reached on day 2 with a marked decrease thereafter. Approximately 20 g of sugar was found in the lower SI declining slightly to 10 days of age, while a much higher level was found in the cecum. Unlike the GIT segments, the relative weight of the pancreas increased during the experimental period (Fig. 5). However, the specific activity of the pancreatic alpha-amylase declined rapidly, reaching a minimum at days 1 and 2, then increasing to reach basal activity levels at 10 days of age.
Discussion The results of the present study describe the progressive changes in GIT development during the immediate post-hatch period in turkey
224
Y. Pinchasov and Y. Noy
poults. The developmental pattern of the GIT differed slightly from that of its contents. Unlike the contents, the relative weights of GIT segments increased with age after hatching, reaching peak values at 4 days of age, followed by gradual decreases. Initial basal content levels were observed in the GIT segments during the first two days post-hatch, presumably due to low feed consumption. In contrast, a substantial increase in content was observed on days 3 to 4 after hatching, corresponding with a marked increase in body weight gain. Dietary starch level ranged between 30 and 32 g/100 g DM diet. Whereas negligible amylolysis occurred in the ventriculus, less than 21 g of starch was found in the crop ingesta (Fig. 4). This indicates the presence of alpha-amylase in the upper GIT, which could be derived from either bacterial or pancreatic sources. Pancreatic digestive enzymes could reach the upper GIT via powerful antiperistaltic contractions, 7,
I
I CROP
1
6 t
DUODENUM P X a
+~----_ 4 LOWER SI 6.5 ' '
I
I
6
0
2
4
I 6
I 6
I 10
I 12
AGE (days)
Fig. 3. pH of ingesta from the various segments of GIT during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of 20-24 birds per age.
known to occur in growing turkeys two to three times per hour (Duke, 1992). Unlike in the ventriculus, starch level in the crop ingesta decreased significantly with age after hatching, concomitant with slight increases in sugar level. Differences in the degree of amylolysis between crop and ventriculus could be explained on the basis of pH. Since the optimal pH for pancreatic amylase activity is 7 (Gapusan et al., 1990), the acidic pH measured in the ventriculus is unfavorable to starch digestion, unlike that measured in the crop (Fig. 3). The results of the present study indicate the newly hatched poults are capable of high amylolytic activity, since a negligible amount of starch was found in the lower SI during the 10 days of the experiment (Fig. 4). The slight decrease in the lower SI sugar content shortly after hatching indicates increased transport ability with age, in contrast with the finding of Esteban et al. (1991), who reported reduced transport of methyl-D-glucose in the duodenum of chicks during the first week after hatching. It can be speculated that the substantial amount of reduced sugars found in the small intestine and cecum (Fig. 4) are of different origins. Whereas sugars found in the small intestine, produced by the activity of pancreatic amylase, are the main byproducts of dietary starch, i.e. glucose, maltose and maltotriose (Sreenath, 1992), the absence of starch in the cecum indicates that its sugars are derived from non-starch polysaccharides, i.e. arabinose, xylose and glucose (Mathers, 1991), the byproducts of extensive bacterial fermentation. Despite the significant increase in pancreas weight after hatching, and the intensive amylolysis observed in the duodenal ingesta, amylase specific activity in the pancreas fell steeply on day 2 and increased gradually thereafter (Fig. 5). A similar pattern has been reported at the beginning of the post-hatch period for pancreatic dipeptidases in chicks (Gallus domesticus, Tarvid, 1992) and for intestinal disaccharides in poults (Sell et al., 1991). These results clearly indicate that the secretory rate of digestive enzymes during the immediate post-hatch period of birds is slightly limited. Although there is evidence for a pretranslational mechanism governing the adaptation of the pancreatic digestive enzymes and resulting in changes in synthesis within hours after a dietary change (Brannon, 1990), this is probably not the case at the beginning of the post-hatch period. At least 2 days of recovery were needed to reach the approximate specific activity observed immediately after hatching (Fig. 5). The described changes in the metabolic and anatomical developmental patterns of the GIT
225
Post-hatch amylolysis development in turkey poults
-I
0
2
4
6
81012
r
1
0
AGE
2
4
6
8
10
25
12
(days)
Fig. 4. Starch (left) and reduced sugar (right) contents in the ingesta of GIT segments during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of lo-20 birds.
during the post-hatch period indicate that the digestive system is slightly limited (days 2 to 4). Due to an adaptation thereafter, the poults are capable of better feed consumption and utilization, leading to a gradual decrease in GIT
References
I
/
I
I
04
capacity at a later age. These results reflect the importance of the “supply organs” (i.e. the GIT and pancreas) in the newly hatched poults, as has been observed in other studies (Nitsan et al., 1991; Sell et al., 1991; Murakami et al., 1992; Pinchasov and Noy, 1993).
iyp /
0.2
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-
400
-
200
-
P’
0 p
oy
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Ok? 0
I 2
I
4
6
AGE
(days)
I
I
6
10
12
Annison G. (1990) Polysaccharides composition of Australian wheats and the digestibility of their starches in broiler chicken diets. Ausrr. J. exp. Agric. 30, 183-186. Bemfeld P. (1955) Amylases a and b. In Merhods in Enzymology Vol. 1, pp. 149-153. Academic Press, New York. Brannon P. M. (1990) Adaptation of the exocrine pancreas to diet. Anna Rev. Nutr. 10, 85-105. Donaldson W. E., Brewer C. E., Ferket P. R. and Christensen V. L. (1992) Posthatch carbohydrate feeding and subsequent performance of turkey poults. Poultry Sci. 71, 128-132. Duke G. E. (1992) Recent studies on regulation of gastric motility in turkeys. Poultry Sci. 71, l-8. Esteban S., Moreno M., Mestre I., Planas J. M. and Tur J. A. (1991) Regional development of alpha-methyl-n-ghtcoside transport in the small intestine of chick embryos and newly-hatched chicks. Arch. Int. Physiol. Biochim. 99, 425-428.
Fig. 5. Pancreas relative weight (V) and the specific activity of pancreatic alpha-amylase (0) during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of 20-24 birds.
Gapusan R. A., Yardley D. G. and Hughes B. L. (1990) The amylase gene enzyme system of chickens. 2. Biochemical characterization of allozymes. Biochem. Genet. 28, 553-560.
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Y. Pinchasov and Y. Noy
Krogdahl A. and Sell J. L. (1989) Influence of age on lipase, amylase, and protease activities in pancreatic tissue and intestinal contents of young turkeys. Poultry Sci. 68, 1561-1568. Mathers J. C. (1991) Digestion of non-starch polysaccharides by non-ruminant omnivores. Proc. Nurr. Sot. 50, 161-172. Moran E. T., Jr. (1982) Starch digestion in fowl. Poultry Sci. 61, 1257-1267. Moran E. T., Jr. (1990) Effects of egg weight, glucose administration at hatch, and delayed access to feed and water on poult at 2 weeks of age. Poulrry Sci. 69, 1718-1723. Murakami H., Akiba Y. and Horiguchi M. (1992) Growth and utilization of nutrients in newly-hatched chick with or without removal of residual yolk. Growth Develop. Aging 56, 75-84. Nitsan Z., Benavraham G., Zoref Z. and Nir I. (1991) Growth and development of the digestive organs and
some enzymes in broiler chicks after hatching. Br. Poult. Sci. 32, 515-523. Pinchasov Y. and Noy Y. (1993) Comparison of post-hatch holding time and subsequent early performance of broiler chicks and turkey poults. Er. Pouk Sci. 34, 111-120. SAS Institute (1985) User’s Guide: Starisrics. 5th Edn. SAS Institute, Cary, NC. Sell J. L., Angel C. R., Piquer F. J., Mallarino E. G. and Al-Batshan H. A. (1991) Developmental patterns of selected characteristics of the gastrointestinal tract of young turkeys. Poultry Sci. 70, 1200-1205. Sreenath H. K. (1992) Studies on starch granules digestion by alpha-amylase. Starch 44, 61-63. Tarvid I. (1992) Effect of early postnatal long-term fasting on development of peptide hydrolysis in chicks. Camp. Biochem. Physiol. lOlA, 161-166. Warriss P. D., Kestin S. C. and Edwards J. E. (1992) Responses of newly hatched chicks to inanition. Vet. Rec. 130,49-53.
1, PP. 221-226,
1994
03OC-9629/94 $6.00 + 0.00
0 1993Pergamon Press Ltd
Early postnatal amylolysis in the gastrointestinal tract of turkey poults Meleagris gaZZopavo Y. Pinchasov and Y. Noy Department of Animal Science, Faculty of Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76-100, Israel The developmental pattern of the gastrointestinal tract (GIT) and its amylolytic capability were examined during the 10 days post-batch in turkey poults. Tbe digestive capacity of the GIT increased to a peak value at 4 days of age and declined thereafter. Substantial amylolysis was evident in tbe crop, whereas an insiguificant amount of starch was hydrolyzed in tbe ventriculus and only residual amounts could be detected in the small intestine or cecum. Tbe results indicate that despite a slight limitation in the secretory rate of pancreatic amylase, newly batched poults are capable of high amylolylic activity. Key words: Turkey (Meleugris gallopavo); Amylolysis; Early growth; Gastrointestinal
development;
Pancreatic amylase; Poults; Starch. Comp. Biochem. Physiol. 107A, 221-226,
1994.
Introduction The rapid transition from yolk-based embryonic nutrition to exogenous dietary-based neonatal nutrition stimulates drastic changes in the digestive system of newly hatched birds. The shift from yolk-originated lipid to dietary carbohydrate as an energy source has been reported to alter the birds’ glucogenic metabolism (Moran, 1990; Donaldson et al., 1992; Warriss et al., 1992) the GIT and its digestive enzymes (Krogdahl and Sell, 1989; Nitsan et al., 1991; Sell et al., 1991; Tarvid, 1992), and the metabolizability of dietary energy and lipid absorption (Murakami et al., 1992). Although the fowl’s ability to release amylase has been stated to be sufficient (Moran, 1982), a decrease in amylase activity has been reported in post-hatch birds (Nitsan et al., 1991; Sell et al., 1991). The low capability to utilize dietary nutrients immediately after hatch is presumed to be, in part, a consequence of incomplete development of the digestive system. A determination
Correspondence ro: Y. Pinchasov, Department of Animal Science, Faculty of Agriculture, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76-100, Israel. Fax: 972-8-465763. Received 8 March 1993; accepted 7 April 1993.
of amylolysis capability, with regards to amylase activity in various sites of the GIT, is essential to assessing starch hydrolysis during the critical post-hatch period. The purpose of the present study was to examine the developmental pattern of the GIT, focusing on its amylolytic capability, during the early posthatch period in turkey poults (Meleugris gallopavo).
Materials and Methods Experimental animals
One hundred and twenty post-hatched male turkey poults (Meleugris gdopuvo) of the Nicholas strain were weighed, wing-banded and moved to an individual battery brooder, located in a temperature- and ventilation-controlled room. They were brooded in groups of three birds/cage for the first three days, then in individual cages to day 10 of the experimental period. Poults were provided with a commercial starter turkey diet, containing 2800 kcal of ME and 280 g CP/kg diet, and free access to food and water. Feed intake was measured per group to 3 days of age, and individually thereafter. Body weight was monitored individually throughout the experiment. Necropsy was
221
222
Y. Pinchasov and Y. Noy
carried out five times during the experiment, on 20 to 24 birds each. The birds were killed by cervical dislocation, the abdominal cavity was opened and residual yolk, liver and pancreas were removed, weighed and frozen (-20°C). The GIT segments were cut and the crop, ventriculus, upper (duodenum) and lower (iejunum + ileum) small intestine (SI), and cecum were weighed with and without contents. The removed ingesta was kept for analysis ( - 20°C). The pH of the ingesta was measured for each segment. Pancreatic alpha-amylase assay The activity of pancreatic alpha-amylase (EC 3.2.1.1) was determined using a modification of Bernfeld’s (1955) procedure. The pancreas was homogenized in 50 volumes of ice-cold deionized water with an Ultra-Turrax homogenizer (setting 5, 30 set). The homogenate was centrifuged at 12,000 g for 15 min (0-4C) and an aliquot of the supernatant was used for enzyme assay. Starch solution (1 g/l00 ml, Merck) gelatinized in 20 mM buffered phosphate solution (BPS) (pH 6.9) containing 10mM NaCl, was used as a substrate. One ml of this solution was added to duplicate supernatant samples and incubated for 3 min at 37°C. For each assay, a soluble starch solution (0 to 8 mg/ml, Merck) was hydrolyzed with alpha-amylase from Aspergillus oryzae (16 U/ml, Sigma) as a standard.
250
1
I
I
I
Statistical analysis Analysis of variance was carried out using the General Linear Model (GLM) procedure of base SAS@ software (SAS Institute, 1985). Duncan’s multiple range test was used to compare differences among segment or and/or age means.
150
/
100
0
Starch and sugar content in diet and GIT Starch levels in the diet and in GIT thyme were determined using a modified method based on that described by Annison (1990). Portions of GIT thyme sampled from each segment were lyophilized and mashed. Triplicate samples (10-20 mg DM) were weighed into screw-cap tubes, mixed with 10 ml of the BPS, and incubated with frequent agitation for 120 min at 100°C. After cooling, alpha-amylase (16 U, Aspergillus oryzae) was added to each tube and incubated for 120 min at 37°C. Each segment was tested in duplicate samples, and in one blank replicate assayed without the added amylase. A soluble starch solution was used as a standard for each assay. The increase in reducing power was measured with DNS reagent at 550 nm in a microplate reader as described above. The amount of reducing sugars was estimated as equal to amount of glucose liberated during starch digestion with alpha-amylase.
T
200
50
One unit (U) of amylase activity was defined as the hydrolysis of 1 mg starch per 3 min at 37°C. An increase in reducing power following hydrolysis measured by dinitrosalicylic acid (DNS) reagent was used to determine the amylolytic activity. After the addition of DNS, reaction tubes were heated for 5 min in boiling water, cooled to room temperature and absorbance was measured at 500 nm. Calorimetric determination was carried out using a computerized microplate reader (Bio-Tek Instruments, EL309).
e-e-. /. I
I
,
I
1
I
0
2
4
6
8
10
12
Result!3
40
30
20
10
0 0
2
4
AGE
6
6
lc
12
(days)
Fig. 1. Body weights (0) and daily feed intake (0) during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of 20-30 birds.
Body weight and daily feed intake increased in a parallel manner during the 10 days posthatch (Fig. 1). The relative weights of the GIT segments increased with age after hatching, reaching peak values at 4 days of age and declining thereafter (Fig. 2). GIT content, however, displayed a different pattern with age, in that a basal value was observed in all segments until 1 day of age, followed by a marked increase (Fig. 2). Peak values of the GIT’s relative contents tended to decrease to 10 days of age, except for duodenal content. Acidic pHs were observed in the GIT segments, especially in the ventriculus, with the
Post-hatch amylolysis development in turkey poults
223
Fig. 2. Gastrointestinal tract (GIT) weights (left) and GIT contents weights (right) during the early post-hatch period in male turkey poults. Lower SI = jejunum + ileum; each symbol represents mean and SE of 20-24 birds.
exception of the lower small intestine which was slightly basic (Fig. 3). pH values increased with age after hatching in the ventriculus and small intestine to 2 days of age and declined thereafter. Only a slight change in pH was observed in the crop with age. A neutral pH was measured in the cecum immediately after hatching, but decreased significantly (P < 0.05) to pH 6 after 1 day, then increased slightly with age for the rest of the IO-day experiment. Starch level in the crop ingesta was significantly (P < 0.05) lower, by about one-third that found in the ventriculus (Fig. 4) or diet (30 to 32 g/100 g DM), while only a residual amount of starch could be detected in the small intestine and cecum throughout the experimental period (Fig. 4). The level of starch in the crop was maximal at 2 days of age (21 g/100 g DM ingesta) and declined significantly (P < 0.05) to 10 days. In ventriculus, starch levels increased 4 days post-hatch, ranging between 31 and 32 g/100 g DM ingesta, thereafter. The amount
of reducing sugars appearing in the crop following the hydrolysis of starch increased after hatching from 10 to approximately 13 g/100 g DM (Fig. 4). In the ventriculus, a peak was reached on day 2 with a marked decrease thereafter. Approximately 20 g of sugar was found in the lower SI declining slightly to 10 days of age, while a much higher level was found in the cecum. Unlike the GIT segments, the relative weight of the pancreas increased during the experimental period (Fig. 5). However, the specific activity of the pancreatic alpha-amylase declined rapidly, reaching a minimum at days 1 and 2, then increasing to reach basal activity levels at 10 days of age.
Discussion The results of the present study describe the progressive changes in GIT development during the immediate post-hatch period in turkey
224
Y. Pinchasov and Y. Noy
poults. The developmental pattern of the GIT differed slightly from that of its contents. Unlike the contents, the relative weights of GIT segments increased with age after hatching, reaching peak values at 4 days of age, followed by gradual decreases. Initial basal content levels were observed in the GIT segments during the first two days post-hatch, presumably due to low feed consumption. In contrast, a substantial increase in content was observed on days 3 to 4 after hatching, corresponding with a marked increase in body weight gain. Dietary starch level ranged between 30 and 32 g/100 g DM diet. Whereas negligible amylolysis occurred in the ventriculus, less than 21 g of starch was found in the crop ingesta (Fig. 4). This indicates the presence of alpha-amylase in the upper GIT, which could be derived from either bacterial or pancreatic sources. Pancreatic digestive enzymes could reach the upper GIT via powerful antiperistaltic contractions, 7,
I
I CROP
1
6 t
DUODENUM P X a
+~----_ 4 LOWER SI 6.5 ' '
I
I
6
0
2
4
I 6
I 6
I 10
I 12
AGE (days)
Fig. 3. pH of ingesta from the various segments of GIT during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of 20-24 birds per age.
known to occur in growing turkeys two to three times per hour (Duke, 1992). Unlike in the ventriculus, starch level in the crop ingesta decreased significantly with age after hatching, concomitant with slight increases in sugar level. Differences in the degree of amylolysis between crop and ventriculus could be explained on the basis of pH. Since the optimal pH for pancreatic amylase activity is 7 (Gapusan et al., 1990), the acidic pH measured in the ventriculus is unfavorable to starch digestion, unlike that measured in the crop (Fig. 3). The results of the present study indicate the newly hatched poults are capable of high amylolytic activity, since a negligible amount of starch was found in the lower SI during the 10 days of the experiment (Fig. 4). The slight decrease in the lower SI sugar content shortly after hatching indicates increased transport ability with age, in contrast with the finding of Esteban et al. (1991), who reported reduced transport of methyl-D-glucose in the duodenum of chicks during the first week after hatching. It can be speculated that the substantial amount of reduced sugars found in the small intestine and cecum (Fig. 4) are of different origins. Whereas sugars found in the small intestine, produced by the activity of pancreatic amylase, are the main byproducts of dietary starch, i.e. glucose, maltose and maltotriose (Sreenath, 1992), the absence of starch in the cecum indicates that its sugars are derived from non-starch polysaccharides, i.e. arabinose, xylose and glucose (Mathers, 1991), the byproducts of extensive bacterial fermentation. Despite the significant increase in pancreas weight after hatching, and the intensive amylolysis observed in the duodenal ingesta, amylase specific activity in the pancreas fell steeply on day 2 and increased gradually thereafter (Fig. 5). A similar pattern has been reported at the beginning of the post-hatch period for pancreatic dipeptidases in chicks (Gallus domesticus, Tarvid, 1992) and for intestinal disaccharides in poults (Sell et al., 1991). These results clearly indicate that the secretory rate of digestive enzymes during the immediate post-hatch period of birds is slightly limited. Although there is evidence for a pretranslational mechanism governing the adaptation of the pancreatic digestive enzymes and resulting in changes in synthesis within hours after a dietary change (Brannon, 1990), this is probably not the case at the beginning of the post-hatch period. At least 2 days of recovery were needed to reach the approximate specific activity observed immediately after hatching (Fig. 5). The described changes in the metabolic and anatomical developmental patterns of the GIT
225
Post-hatch amylolysis development in turkey poults
-I
0
2
4
6
81012
r
1
0
AGE
2
4
6
8
10
25
12
(days)
Fig. 4. Starch (left) and reduced sugar (right) contents in the ingesta of GIT segments during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of lo-20 birds.
during the post-hatch period indicate that the digestive system is slightly limited (days 2 to 4). Due to an adaptation thereafter, the poults are capable of better feed consumption and utilization, leading to a gradual decrease in GIT
References
I
/
I
I
04
capacity at a later age. These results reflect the importance of the “supply organs” (i.e. the GIT and pancreas) in the newly hatched poults, as has been observed in other studies (Nitsan et al., 1991; Sell et al., 1991; Murakami et al., 1992; Pinchasov and Noy, 1993).
iyp /
0.2
P
V’
0.0
-
400
-
200
-
P’
0 p
oy
_\/ 0
Ok? 0
I 2
I
4
6
AGE
(days)
I
I
6
10
12
Annison G. (1990) Polysaccharides composition of Australian wheats and the digestibility of their starches in broiler chicken diets. Ausrr. J. exp. Agric. 30, 183-186. Bemfeld P. (1955) Amylases a and b. In Merhods in Enzymology Vol. 1, pp. 149-153. Academic Press, New York. Brannon P. M. (1990) Adaptation of the exocrine pancreas to diet. Anna Rev. Nutr. 10, 85-105. Donaldson W. E., Brewer C. E., Ferket P. R. and Christensen V. L. (1992) Posthatch carbohydrate feeding and subsequent performance of turkey poults. Poultry Sci. 71, 128-132. Duke G. E. (1992) Recent studies on regulation of gastric motility in turkeys. Poultry Sci. 71, l-8. Esteban S., Moreno M., Mestre I., Planas J. M. and Tur J. A. (1991) Regional development of alpha-methyl-n-ghtcoside transport in the small intestine of chick embryos and newly-hatched chicks. Arch. Int. Physiol. Biochim. 99, 425-428.
Fig. 5. Pancreas relative weight (V) and the specific activity of pancreatic alpha-amylase (0) during the early post-hatch period in male turkey poults. Each symbol represents mean and SE of 20-24 birds.
Gapusan R. A., Yardley D. G. and Hughes B. L. (1990) The amylase gene enzyme system of chickens. 2. Biochemical characterization of allozymes. Biochem. Genet. 28, 553-560.
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Y. Pinchasov and Y. Noy
Krogdahl A. and Sell J. L. (1989) Influence of age on lipase, amylase, and protease activities in pancreatic tissue and intestinal contents of young turkeys. Poultry Sci. 68, 1561-1568. Mathers J. C. (1991) Digestion of non-starch polysaccharides by non-ruminant omnivores. Proc. Nurr. Sot. 50, 161-172. Moran E. T., Jr. (1982) Starch digestion in fowl. Poultry Sci. 61, 1257-1267. Moran E. T., Jr. (1990) Effects of egg weight, glucose administration at hatch, and delayed access to feed and water on poult at 2 weeks of age. Poulrry Sci. 69, 1718-1723. Murakami H., Akiba Y. and Horiguchi M. (1992) Growth and utilization of nutrients in newly-hatched chick with or without removal of residual yolk. Growth Develop. Aging 56, 75-84. Nitsan Z., Benavraham G., Zoref Z. and Nir I. (1991) Growth and development of the digestive organs and
some enzymes in broiler chicks after hatching. Br. Poult. Sci. 32, 515-523. Pinchasov Y. and Noy Y. (1993) Comparison of post-hatch holding time and subsequent early performance of broiler chicks and turkey poults. Er. Pouk Sci. 34, 111-120. SAS Institute (1985) User’s Guide: Starisrics. 5th Edn. SAS Institute, Cary, NC. Sell J. L., Angel C. R., Piquer F. J., Mallarino E. G. and Al-Batshan H. A. (1991) Developmental patterns of selected characteristics of the gastrointestinal tract of young turkeys. Poultry Sci. 70, 1200-1205. Sreenath H. K. (1992) Studies on starch granules digestion by alpha-amylase. Starch 44, 61-63. Tarvid I. (1992) Effect of early postnatal long-term fasting on development of peptide hydrolysis in chicks. Camp. Biochem. Physiol. lOlA, 161-166. Warriss P. D., Kestin S. C. and Edwards J. E. (1992) Responses of newly hatched chicks to inanition. Vet. Rec. 130,49-53.