Printer Friendly

Development of gastric and pancreatic enzyme activities and their relationship with some gut regulatory peptides in grazing sheep.

INTRODUCTION

During the first post-natal months, the young ruminant is faced with three types of situations requiring physiological and digestive adaptation: adaptation to the extra uterine environment, maintenance in an extended preruminant stage and weaning (Thivend et al., 1980). The effects of age on pancreatic secretions have been more thoroughly investigated in monogastric animals (Corring et al., 1978; Kretchmer, 1985) than in ruminant species (Huber et al., 1961; Guilloteau et al., 1983, 1984, 1985). However, few studies report effects of age on gastric enzyme secretions in young mammals (Walker, 1959; Hartman et al., 1961; Henschel, 1973; Garnot et al., 1977; Foltmann et al., 1981). There are some reports on digestive physiology for non-grazing lambs; for example, it is generally acknowledged that the pre-ruminant abomasum characteristically secretes large amounts of chymosin, which, with pepsin and hydrochloric acid, coagulates milk casein. At 2 days of age there is a threshold of development of enzyme secretion potentiality in lambs. Quantities of gastric enzymes in relation to empty live weight increase between birth and 2 days, but that of chymosin then decreases, whereas pepsin does not change significantly. The evolution of pancreatic enzyme activity was usually the reverse of that of chymosin; however, trypsin activity was low at birth (Guilloteau et al., 1983). But very few studies report on digestive physiology for grazing lambs, and especially in grazing lambs distributed over a plateau at 2,600 m above sea level.

In China, lambs usually stay with their mothers until weaning of non-grazing lambs at the age of two months and of grazing lambs usually at the age of four months. In our experiment, the animals were Gansu Alpine Fine-wool sheep, which are distributed over the northern slope of the east Qilian mountains at the border of Gansu and Qinghai (101[degrees]45'E, 37[degrees]53'N). The area is a cold alpine pastoral range, and belongs to sub-alpine meadow and mountain rangeland. The altitude ranges from 2,600 m to 3,500 m, even to 4,000 m, and the cold season is longer and there is shortage of pasture forage. Gansu Alpine Fine-wool sheep are a special breed grazing on the plateau at 2,600 m above sea level. The study indicated that grazing lambs had a lot of grass in the rumen at 7 days post-partum, which means that at 7 days of age the lambs can eat solid food but are still maintained in the pre-ruminant state until day 28. Solid food enters the rumen, and an increasing amount of microbial digestion is observed together with increased development of the forestomachs. At the end of weaning (4 months old), lambs are no longer pre-ruminant but ruminant. Depending on the feeding conditions, i.e., milk or solid food, substantial differences in the enzyme activities along the digestive tract occur between these two quite different physiological situations. The lamb, therefore, is an interesting model for investigating the effects of development on digestive functions, and studies can result in useful parameters on digestive physiology for grazing lambs on the plateau, regardless of the nutritional substrates involved.

The present work aimed to study the patterns of abomasal and pancreatic enzyme secretions in grazing lambs. The development of gastric and pancreatic digestive functions was tentatively correlated with changes in the plasma concentrations of five gut regulatory peptides.

MATERIALS AND METHODS

Study site description

The animals were from Huangcheng sheep breeding testing farm of Gansu, China. The farm was the first breeding farm for Gansu Alpine Fine-wool sheep which is located at Huangcheng District in the Sunan Yugu autonomous county of Gansu Province of China, which is on the northern slope of the east Qilian mountains at the border of Gansu and Qinghai (101[degrees]45'E, 37[degrees]53'N). The area is cold alpine pastoral range and belongs to sub-alpine meadow and mountain rangeland. The altitude is from 2,600 m to 3,500 m, even up to 4,000 m. The climate is variable over the year and 4 seasons are not clear. Plateau mainland climate, winds and dryness. The climatic characteristics during the year are drought and cold in winter, warm and humid in summer. Mean annual temperature is 0.6 to 3.8[degrees]C, the highest is 31[degrees]C in July, and lowest is -29[degrees]C in January. Annual sunshine hours are 2,272 h. The absolute frost-free period is 45 to 60 days. Mean annual rainfall is 361.6 mm, annual evaporation is 1,111.9 mm, mean annual relative humidity is 38% to 58%. The natural grass sprouts in April and dies in September, the wilt period of pasture is above 7 months. The soil type is kastanozem, mountain phaeozem and cinnamon soil. The soil is fertile, and water is abundant. The types of natural grassland are grass family, sedge family, weeds of grass family and sedge family and scrub weeds. The vegetation mainly consists of grass family and sedge family as well as a few pea family.

Animals and feeding

There were about 10,000 Gansu Alpine Fine-wool lambs in a breeding flock single born between April 22 and May 22 in 2007. Lambs suckled their dams and grazed on native grassland pasture, with no additional feed. Animals were penned at pasture at night without access to feed and water. There were no feed supplements, but a salt mineral mix was provided to the lambs throughout the year; animals had access to water only once a day. Lambs were not weaned until 4 months old, and therefore they remained with their dams throughout the lactation period. Forty-four single-born male lambs obtained at birth from the herd were randomly distributed into eight groups (Table 1). The experimental period was from May to June, and grass samples were collected according to pasture type, one pasture type from five sampling spots and each sampling area was 1 [m.sup.2]. Grass kinds included bush cinquefoil (Potentilla fruticosa Linn.), linearleaf kobresia (Kobresia capillifolia (Decne.) Clarke), larch needlegrass (Stipa grandis P.Smirn), bellard kobresia (Kobresia bellardii(All.) Degl.) , and mountain willow (Salix oritrepha Schneid). The original samples were clipped. Then, the samples were divided into four equal parts and a randomly chosen part was used to analyze the composition. Nutrient composition of grazed pasture is presented in Table 2.

Tissue sampling

On the day of slaughter at 3, 7, 14, 21, 28, 42 and 56 days of age the lambs were fed as usual; the lambs slaughtered at 0 d of age were fed nothing. Lambs were removed from their dams at approximately 09:00 h, transported to the research laboratory and final weights were obtained and recorded. Lambs were slaughtered by severing the jugular vein. The abdominal cavity was opened and the entire gastrointestinal tract was removed. The pancreas was carefully dissected free, cleaned of extraneous tissue, weighed, wrapped in pledget and immediately placed into liquid nitrogen. The abomasum was cut open, 100 to 200 g abomasal contents were collected and put into liquid nitrogen, then emptied of its contents, rinsed with ice-cold isotonic saline, gently blotted with filter paper, defatted, weighed and spread out onto a glass plate lying on ice. Finally, the abomasal mucosa of the cardiac, fundic and pyloric gland regions were scraped off with a glass slide, and put into liquid nitrogen. All the frozen samples were subsequently stored at -80[degrees]C until use.

Sample preparation

The abomasal mucosa and pancreas were all minced with scissors, and homogenized in 5 volumes of ice-cold 0.4 M KC1 (W/V = 1:5) for 45 s in an ice-cold vessel (4[degrees]C overnight). The homogenate was centrifuged at 15,000 g (4[degrees]C for 20 min), and aliquots of the supernatant were stored at -80[degrees]C.

Enzyme analyses

The homogenate of abomasal mucosa was analyzed for chymosin activity using the method described by Arima (1967). Pepsin activity and pregastric esterase activity were determined by spectrophotometry using bovine haemoglobin and olive oil, respectively, as substrates. The activities of pancreatic trypsin and chymotrypsin were determined by spectrophotometry using benzoyl-Larginine-p-nitroanilide and N-glutaryl-L-phenylalanine-p-nitroanilide, respectively, as substrates. Lipase activity was determined by spectrophotometry using olive oil as a substrate. The a-amylase and lactase activities were assayed using starch and ONPG (o-nitrophenyl-[beta]-D-galactoside), respectively, as substrates.

The results are expressed as enzyme quantities per milligram of tissue protein content for all the enzymes.

Plasma gut regulatory peptide analysis

Blood was collected on EDTA (4%) from an external jugular vein at 9:00 h on the morning before slaughter. Plasma samples were stored at -20[degrees]C and concentrations of five gut regulatory peptides were subsequently determined by ELISA methods.

Statistical analysis

Variance analysis was used to assess the effects of age, and Tukey's test was used to classify the means. Correlation coefficients were used to study the relationships between enzyme activities and plasma concentrations of the gut regulatory peptides. Values were considered to be significant at p<0.05.

RESULTS

Development of abomasum pH

pH either in abomasal contents or in gland region mucosa was highest at birth and then decreased with increasing age (except for a high value at 28 d in contents), but remained within the optimal range for enzyme activity. pH was generally similar in each gland region mucosa (Table 3).

Abomasal enzymes

In lambs, the specific activity of chymosin in abomasal contents was highest at birth, but tended to decrease between 0 and 56 d, possibly due to dilution by the intake of milk and grass. There were more differences in enzyme activity of abomasal contents among individuals, possibly affected by enzyme secretion, milk and grass intake. At d28, d35 and d42 the enzyme activity was high for unknown reasons. Between days 0 and 14 the specific activity of chymosin was high in both contents and mucosa, and thereafter it decreased. Between days 0 and 14 the specific activity was lower in the mucosa of the fundic gland region than in the cardiac and pyloric gland regions, and was similar in all regions thereafter except for d28 in the cardiac gland region (Table 4).

Compared to chymosin, the specific activity of abomasal pepsin was lower. Pepsin activity was high at birth and increased little with increasing age. There was a little difference in different gland region, in fundic gland region mucosa which was highest, and in pyloric gland region was lowest;and in contents which was lowest because of milk and grass diluted (0.003 to 0.009 U/mg protein)(Table 5).

Pregastric esterase activity in abomasal contents was high at birth, and decreased thereafter by milk and grass diluted. In d28 it tended to increase. The enzyme is secreted by the tongue root. It seemed that the secretion capacity had little change from day 0 to 56 (Table 6).

Pancreatic enzymes

The specific activity of trypsin was higher than that of a-amylase, chymotrypsin and lipase. Lactase activity was low. The specific activity of all the tested pancreatic enzymes fluctuated with increasing age except that of chymotrypsin which tended to increase after d14.

Plasma concentrations of gut regulatory peptides

In lambs, considerable changes in the plasma concentrations of gastrin, GIP, CCK, and sectin (Table 8) occurred with increasing age, especially between days 0 and 42, which tended to decrease. CCK concentration was sharply decreased by 1/15 between 3 and 42 d, but increased by 3-fold between d 42 and 56. The secretin and gastrin concentrations reached a peak at d 3, and thereafter which decreased and on d 42 were as 45% and 36% as of d 3. GIP concentration was high between 0 and 7 d and decreased at d 14 and d 28. At d 42 it decreased 9.2% of d 7. Increased plasma PP concentration was recorded between 0 and 42 d.

Correlation analyses

No significant correlation was found between plasma concentrations of CCK,secretin, PP, gastrin, GIP and chymosin activity in the contents (p>0.05). By contrast, significant positive correlations were observed between plasma concentrations of CCK, secretin, gastrin, GIP and the chymosin activity in the mucosa of the cardiac, fundic and pyloric gland regions (p<0.01 or p<0.05), while significant negative correlation was recorded between plasma concentration of PP and the chymosin activity in the mucosa of the fundic and pyloric gland regions (p<0.01 or p<0.05). Significant negative correlations were found between plasma concentrations of CCK, secretin, gastrin, GIP and pepsin activity in the contents (p<0.05). Only plasma concentration of GIP was positively correlated with the specific activity of pepsin in the mucosa of the pyloric gland region (p<0.05). The plasma concentration of PP was positively correlated with the specific activity of pepsin in the mucosa of the cardiac gland region while negatively correlated with the pyloric gland region (p<0.05). Significant negative correlations were recorded between the plasma concentrations of CCK, secretin, gastrin and pregastric esterase activity of the contents (p<0.05), and no significant correlation was observed between the plasma concentrations of PP, GIP and pregastric esterase activity (p>0.05).

The plasma concentrations of CCK, secretin, PP, gastrin and GIP were all positively or negatively correlated with the specific activity of chymotrypsin (p<0.01 or p<0.05). The plasma concentrations of CCK and GIP were negatively correlated with the activity of lactase (p<0.05). Moreover, negative correlation was observed between a-amylase activity and the plasma concentration of secretin (p<0.05). No significant correlation was found between the plasma concentrations of CCK, secretin, PP, gastrin, GIP and the lipase, trypsin activities (p>0.05).

DISCUSSION

Grazing condition and grazing pasture

Gansu Alpine Fine-wool sheep grazes on alpine cold pastoral range which belongs to sub-alpine meadow and mountain rangeland. The altitude is from 2,600 m to 3,500 m, even to 4,000 m. The climate is plateau mainland climate, winds and dryness. The climatic characteristics in a year are drought and cold in winter, warm and humidity in summer. Mean annual temperature is 0.6 to 3.8[degrees]C, the highest is 31[degrees]C in July, and lowest is -29[degrees]C in January. Annual sunshine hours are 2,272 h. The absolute frost-free period is 45 to 60 days. Mean annual rainfall is 361.6 mm, annual evaporation is 1,111.9 mm, mean annual relative humidity is 38% to 58%. The natural grass sprouts in April and dies in September, the wilt period of pasture is above 7 months. The soil type is kastanozem, mountain phaeozem and cinnamon soil. The types of natural grassland are grass family, sedge family, weeds of grass family and sedge family, scrub weeds. The vegetation mainly consists of grass family and sedge family as well as a few pea family.

Lambs suckle their mothers and graze on native grassland pasture, with no additional feed. Animals are penned at pasture at night without access to feed and water. There are no feed supplements, but a salt mineral mix is provided to lambs throughout the year, animals have access to water only once a day. Lambs are not weaned until 4 months old.

The abomasal pH

The pH changed from 2.96 to 4.7 in the abomasal contents and from 2.8 to 4.8 in the mucosa.The pH was relatively low in the mucosa of the fundic gland region. The pH of pancreas didn't change with increasing age. The results agree with previous findings in young ruminants (Gorrill et al., 1967). But these are the first for lambs on pasture in China.

Change of abomasal enzyme activities

All the enzyme activities recorded in the abomasum were high at birth, agree with the results reported by previous reports (Huber, 1969; Era Berinkovd, 1988). Pepsin activity was lower than that of chymosin.This finding confirmed the importance of chymosin in milk clotting, because its activity level was 100-200% higher than that reported for pepsin (Raymond et al., 1973). Pepsin activity tended to increase with increasing age, but chymosin activity reversed. After d14 chymosin activity in the mucosa decreased sharply. The results agree with the most reports about chymosin of calves abomasal mucosa (Andren, 1980; Valles, 1980), contents (Garnot et al., 1977), gastric juice (Alais, 1963; Hill et al., 1970; Kirton et al., 1971; Hagyard and Davey, 1972) and lambs abomasal mucosa (Guilloteau, 1983), but disagree with Garnot (Garnot et al., 1977). The decreasing chymosin activity may be the increasing grass intake and decreasing milk intake after d14, which weaken the stimulus of abomasum resulting in the decrease of chymosin secretion. According to the previous reporting, milk (most probably its casein fraction) is responsible for the activation of chymosin secretion (Garnot et al., 1977).

Pepsin activity in abomasal contents was relatively high and decreased to the lowest at d3, possibly because of dilution by milk intake, and thereafter it began to increase. The development of secretion potentiality of abomasum appeared to depend on age and intake. In the testing, pepsin activity in the mucosa of the cardiac and fundic gland regions was higher than that in the pyloric gland region. As a whole, the changes of pepsin activity agree with previous findings in young ruminants (Guilloteau et al., 1984; Huber et al., 1961; Isabelle et al., 1992). Pregastric esterase activity was high at birth, at d 3 which decreased by dilution of milk intake and increased a little after d 28. It appeared that the secretion potentialities of root of tongue changed little between d 0 and 56.

Change of pancreatic enzyme activities

Trypsin, chymotrypsin are all secreted by pancreas. It also secretes carboxypeptidases, nucleic acid enzyme and so on. All those enzymes flow into small intestine through bile duct along with pancreatic liquid. It reported that pancreatic proteolytic enzyme contributes approximately 72% of the protein in pancreas. Trypsin and chymotrypsin activities were 6-fold of the summation of a-amylase, lactase as well as lipase, and erepsin secreted by small intestine epithelia, so the digestibility of protein was very strong. The pancreas was relatively mature at birth, but the relative weight (% body weight) of it was still growing, and the function was increasing after d 21. Trypsin activity changed little with increasing age,but chymotrypsin activity tended to increase after d 14. Lipase activity existed at birth but change little with age. Under grazing conditions, the dietary contain more fat only in the period of suckling. The fat in the grass is about 1% to 4%, which is hydrolyzed by rumen microorganism into digestible fatty acid (salt) and flows into small intestine. Lipase activity in pancreas and small intestine mucosa increased little with increasing age, but still digested the fat in the diet. Pancreatic lactase activity was high at birth, but was lower than that in small intestine mucosa. Disaccharidases (lactase and maltase) are mainly secreted by small intestine mucosa and epithelium.

[alpha]-Amylase is secreted by pancreas and small intestine. According to the reports, in young pigs and calves, a-amylase was low at birth and increased with age. The dietary of weaning animals doesn't add starch generally. In the present study, the animals were grazing lambs, starch in the dietary was very little, but a-amylase activity was observed in pancreas at birth. Pancreatic activity was greater than that in small intestine mucosa. Pancreatic [alpha]-amylase activity had insignificant change with increasing age.

Relationships with gut regulatory peptides

Significant change was observed in plasma concentrations of gut regulatory peptides. High concentrations of gastrin, CCK and secretin at d3, and GIP at 7 d in plasma were observed. Thereafter they decreased and at d 42 reached the lowest point. By contrast, the concentration of plasma PP was relatively low at birth and increased with age and by d42 it reached the highest. The changes of all plasma gut regulatory peptides tested were consistent with the change of the rumen function. Adaptation of chymosin activity to dietary changes under the grazing conditions may be influenced by the decrease of CCK, secretin, gastrin, GIP, or increase of PP concentrations. In the present study, all the tested plasma concentrations of gut regulatory peptides seemed to be involved in the regulation of abomasal mucosa chymosin activity, because it was highly correlated with abomasal mucosa chymosin activity. And the change of CCK, secretin, gastrin and GIP were consistent with the change of chymosin activity. All of them decreased with increasing age, while PP reversed. On the contrary, all the tested plasma concentrations of gut regulatory peptides did not seem to be involved in the regulation of pepsin and pregastric esterase activities, because they had little correlation with the specific activity of them. This disagreed with previous reporting (Daviccon et al., 1980; Pierzynowski et al., 1991), maybe influenced by the management system (grazing) or the time of blood collection. The plasma concentrations of all the tested plasma gut regulatory peptides may have decisive, but opposite, influences on pancreatic chymotrypsin is supported by the correlations observed with the pancreatic chymotrypsin. But they did not seem to be involved in the regulation of pancreatic trypsin and lipase, because they were little correlated with trypsin and lipase activities. Only secretin seemed to be involved in the regulation of pancreatic a-amylase because they negatively correlated with each other. CCK, GIP seemed to be involved in the regulation of pancreatic lactase because they were negatively correlated with each other (but we didn't find reports at present), because lactase always be deemed to be secreted by small intestine mucosa. But in the present study considerable lactase activity was observed.

CONCLUSION

pH was acidic in abomasum (relatively lower in fundic gland region) and alkaline and stable in pancreas. [alpha]-Amylase, lactase, lipase, trypsinase and chymotrypsin activities were observed in pancreas at birth, and changed little with increasing age. The concentrations of gastrin, GIP, CCK, and secretin in plasma tended to decreasing with increasing age, and PP tended to increase. The correlation between the concentration of pancreatic polypeptide and other regulatory peptide concentrations seemed to be negative. Gastrin, GIP, CCK, and secretin may play a positive regulatory function to chymotrypsin activity in abomasum, while pancreatic polypeptide had a negative regulatory function. The tested plasma regulatory peptides were insignificantly correlated with pepsin and pregastric esterase activities in abomasum. The plasma regulatory peptides correlated with chymotrypsin activity in pancreas positively or negatively; PP positively regulates a-amylase activity in pancreas; GIP and CCK negatively regulate the lactase activity in pancreas.

Received August 26, 2010; Accepted November 12, 2010

REFERENCES

Alais, C. 1963. Etude de la secretion d'enzymes coagulant dans la caillette de l'agneau. Ann. Biol. Anita. Biochim. Biophys. 3:65.

Andren, A., L. Bjorck and O. Claesson. 1980. Quantification of chymosin (rennin) and pepsin in bovine abomasum by rocket immuno-electrophoresis. Swed. J. Agric. Res. 10:123.

Arima, K. 1967. Milk-clotting enzyme from microorganism,part I,screening test and identification of the potent fungus. Agric. Biol. Chem. 31:540-545.

Corring, T., A. Aumaltre and G. Durand. 1978. Development of digestive enzymes in the piglet from birth to 8 weeks. I. Pancreas and pancreatic enzymes. Nutr. Metab. 22:231-243.

Davicco, M. J., J. Lefaivre, and J. P. Barlet. 1980. The endocrine regulation of exocrine pancreas in preruminant milk-fed calves. Ann. Rech. Vet. 11(2):123-132.

Era Berinkovd, Jiri Sajdok, Pavel Rauch and Jan Kag. 1988. Determination of chymosin and bovine pepsin content of bovine rennets by high performance liquid chromatography. Neth. Milk Dairy J. 42:337.

Foltmann, B., A. L. Jensen, P. Lonblad, E. Smidt and N. H. Axelsen. 1981. A developmental analysis of the production of chymosin and pepsin in pigs. Comp. Biochem. Physiol. 68:9.

Garnot, P., R. Toullec, J. L. Thapon, T. P. Martin and M. T. Hoang. 1977. Influence of age, dietary protein and weaning on calf abomasal enzymic secretion. J. Dairy Res. Feb;44(1):9-23.

Garnot, P., R. Toullec, J. L. Thapon, P. Martin, M. T. Hoang, C. M. Mathieu and B. Ribadeau-Dumas. 1977. Influence of age, dietary protein and weaning on calf abomasal enzymatic secretion. J. Dairy Res. 44:9.

Guilloteau, P., T. Corring, R. Toullec and J. 1984. Enzyme potentialities of the abomasum and pancreas of the calf. I. Effect of age in the preruminant. Reprod. Nutr. Dev. 24(3):315-325.

Guilloteau, P., T. Corring, Pascaline Garont, P. Martin, R. Toullec and G. Durand. 1983. Effects of age and weaning on enzyme activities of abomasum and pancreas of the lamb. J. Dairy Sci. 66:2373-2385.

Guilloteau, P. 1983. Effects of age and weaning on enzyme activities of abomasum and pancreas of the lamb. J. Dairy Sci. 66:2373-2385.

Guilloteau, P., T. Corring, P. Garnot, P. Martin, R. Toullec and G. Durand. 1983. Effects of age and weaning on enzyme activities of abomasum and pancreas of the lamb. J. Dairy Sci. 66:2373-2385.

Guilloteau, P., T. Corring, R. Toullec and R. Guilhermet. 1985. Enzyme potentialities of the abomasum and pancreas of the calf. II. Effects of weaning and feeding a liquid supplement to ruminant animals. Reprod. Nutr. Dev. 25:481-493.

Guilloteau, P., T. Corring, R. Toullec and J. Robelin. 1984. Enzyme potentialities of the abomasum and pancreas of the calf. I.Effect of age in the preruminant. Reprod. Nutr. Dev. 24:315-325.

Hagyard, C. J. and Davey CL. Rennin yield. 1972. The effects of bobby calf age and degree of starvation. New Zealand J. Dairy Sci. Technol. 7:140.

Hartman, P. A., V. W. Hays, R. C. Baker, L. H. Neagle and D. V. Catron. 1961. Digestive enzyme development in the young pig. J. Anim. Sci. 20:114.

Henschel, M. J. 1973. Comparison of the development of proteolytic activity in the abomasums of the preruminant calf with that in the stomach of the young rabbit and guinea-pig. Br. J. Nutr. 30:285.

Hill, K. J., D. E. Noakes and R. A. Lowe. 1970. Gastric digestive physiology of the calf and piglet.pp.166-179 in Physiology of digestion and metabolism in the ruminant (Ed. A. T. Phillipson). IIIth Int. Symp. Ruminant Physiol., Oriel Press Ltd., Newcastle upon Tyne.

Huber, J. T., N. L. Jacobson, R. S. Allen and P. A. Hartman. 1961. Digestive enzyme activities in the young calf. J. Dairy Sci. 44:1494.

Huber, J. T. 1969. Calf Nutrition and rearing.Development of the digestive and metabolic apparatus of the calf. J. Dairy Sci. 52:1303.

Huber, J. T., N. L. Jacobson, R. S. Allen and P. A. Hartman. 1961. Digestive enzyme activities in the young calf. J. Dairy Sci. 44:1494-1501.

Isabelle Le Huerou-luron, Paul Guilloteau, Catherine Wicker-Planquart, Jean-Alain Chayvialle, John Burton, Aziz Mouats, Rene Toullec and Antoine Puigserver. 1992. Gastric and pancreatic enzyme activities and their relationship with some gut regulatory peptides during postnatal development and weaning in calves. J. Nutr. 122:1434-1445.

Kirton, A. H., D. J. Paterson and N. H. Clarke. 1971. Slaughter information and rennin production from bobby calves. New Zealand J. Agric. Res. 14:397.

Kretchmer, N. 1985. Weaning: enzymatic adaptation. Am. J. Clin. Nutr. 41:391-398.

Pierzynowski, S. G., R. Zabielsli, B. R. Westrom, M. Mikolajczyk and W. Barej. 1991. Development of the exocrine pancreatic function in chronically cannulated calves from the preweaning period up to early rumination. J. Anim. Physiol. Anim. Nutr. 65:165-172.

Raymond, M. N., E. Ericas, R. Salesse, F. Gamier, P. Garnot and B. Ribadeau-Dumas. 1973. Proteolytic unit for chymosin (rennin) activity based on a reference synthetic peptide. J. Dairy Sci. 56:419-425.

Thivend, P., R. Toullec and P. Guilloteau. 1980. Digestive adaptation in the preruminant. 561-586 in Digestive physiology and metabolism in ruminants (Ed. Y. Ruckebusch and P. Thivend). Vth Int. Symp. Rumin. Physiol. M.T.P. Press Ltd., Lancaster.

Valles E. 1980. Les pepsins gastriques bovines utilisees en fromagerie. These Doct. Ing, Paris.

Walker, D. M. 1959. The development of the digestive system of the young animal. IV. Proteolytic enzyme development in the young lamb. J. Agric. Sci. 53:381.

Lang Xia (1,2,*) and Wang Cailian (1)

(1) Faculty of Animal Science and Technology, Gansu Agricultural University, Lanzhou, 730070, China

(2) Lanzhou Institute of Animal Science and Veterinary Pharmaceutics Sciences, Chinese Academy of Agricultural Science (CAAS), Lanzhou, 730050, China.

* Corresponding Author : Lang Xia. E-mail: langxiax@163.com
Table 1. Base status of the test lambs

Age   Slaughter       Birth weight         Slaughter weight
(d)   number (n)          (kg)                   (kg)

 0       6         4.02 [+ or -] 0.175    4.02 [+ or -] 0.175
 3       8         3.97 [+ or -] 0.283    4.57 [+ or -] 0.488
 7       5         3.86 [+ or -] 0.498    5.11 [+ or -] 0.244
14       5         3.59 [+ or -] 0.397    6.84 [+ or -] 0.996
21       5         4.19 [+ or -] 0.394    7.01 [+ or -] 0.415
28       5         4.14 [+ or -] 0.397    8.86 [+ or -] 1.841
42       5         3.83 [+ or -] 0.303   10.20 [+ or -] 0.837
56       5         4.11 [+ or -] 0.292   16.44 [+ or -] 2.674

Age        Daily gain              Withers height
(d)            (g)                      (cm)

 0              --              36.00 [+ or -] 2.828
 3    229.58 [+ or -] 118.127   36.38 [+ or -] 2.973
 7    178.86 [+ or -] 49.54     38.20 [+ or -] 1.095
14    232.14 [+ or -] 66.047    39.80 [+ or -] 1.924
21    134.19 [+ or -] 27.376    41.80 [+ or -] 1.924
28    168.57 [+ or -] 72.464    39.00 [+ or -] 3.674
42    151.67 [+ or -] 21.716    47.20 [+ or -] 1.924
56    220.18 [+ or -] 46.73     52.60 [+ or -] 2.793

Age       Body length            Heart girth
(d)          (cm)                    (cm)

 0    29.83 [+ or -] 1.472   34.50 [+ or -] 2.739
 3    32.88 [+ or -] 1.553   36.50 [+ or -] 1.690
 7    35.20 [+ or -] 1.643   38.60 [+ or -] 2.302
14    36.60 [+ or -] 1.673   43.40 [+ or -] 2.191
21    38.80 [+ or -] 0.837   42.40 [+ or -] 1.517
28    40.20 [+ or -] 1.789   47.40 [+ or -] 3.362
42    44.20 [+ or -] 2.588   49.40 [+ or -] 2.074
56    51.40 [+ or -] 2.302   61.60 [+ or -] 3.715

* Values are means [+ or -] SEM.
** Statistics is Tukey'test under One-Way
ANOVA in SPSS12.0.

Table 2. Nutrient component of pasture *

Month    DM       CP     EE     NDF     ADF     Ash    Ca      P

5       62.22   10.33   2.19   71.67   37.98   11.31   0.61   0.10
6       37.36   10.04   2.14   71.57   39.35   11.16   0.59   0.10

* They were expressed on dry matter bases but dry matter.

** DM = Dry matter; CP = Crude protein; EE = Ether extract;
NDF = Neutral detergent fiber; ADF = Acid detergent fiber.

Table 3. Changes of pH of abomasal contents and mucosa

Age   Slaughter                               Cardiac gland region
(d)   number(n)        Contents                      mucosa

 0       6        4.67 [+ or -] 0.681 (a)    4.74 [+ or -] 0.896 (a)
 3       8        3.39 [+ or -] 0.461 (ab)   3.53 [+ or -] 0.349 (a)
 7       5        3.36 [+ or -] 0.474 (ab)   3.75 [+ or -] 0.621 (a)
14       5        3.37 [+ or -] 0.538 (ab)   3.48 [+ or -] 0.674 (a)
21       5        3.29 [+ or -] 0.896 (ab)   3.75 [+ or -] 1.041 (a)
28       5        4.09 [+ or -] 1.331 (ab)   3.26 [+ or -] 0.644 (a)
42       5        3.59 [+ or -] 0.736 (ab)   3.62 [+ or -] 0.390 (a)
56       5        2.96 [+ or -] 0.184 (b)    3.41 [+ or -] 0.175 (a)

Age   Fundic gland region        Pyloric gland region
(d)         mucosa                      mucosa

 0    4.43 [+ or -] 0.794 (a)    4.36 [+ or -] 0.745 (a)
 3    3.54 [+ or -] 0.362 (ab)   3.49 [+ or -] 0.326 (a)
 7    3.39 [+ or -] 0.602 (ab)   3.27 [+ or -] 0.815 (a)
14    3.62 [+ or -] 0.536 (ab)   3.52 [+ or -] 0.488 (a)
21    3.30 [+ or -] 1.070 (ab)   3.35 [+ or -] 0.905 (a)
28    3.16 [+ or -] 0.717 (ab)   3.32 [+ or -] 0.750 (a)
42    2.86 [+ or -] 0.789 (b)    3.55 [+ or -] 0.579 (a)
56    2.94 [+ or -] 0.485 (b)    3.41 [+ or -] 0.357 (a)

* Values are means [+ or -] SEM.

** Statistics is Tukey'test under One-Way ANOVA in SPSS12.0.

Table 4. Developmental changes of abomasal chymosin (U/mg protein)

Age   Slaughter            Contents
(d)   number (n)

 0        6        43.00 [+ or -] 34.430 (a)
 3        8         6.92 [+ or -] 2.867 (a)
 7        5         4.21 [+ or -] 1.985 (a)
14        5         6.64 [+ or -] 2.991 (a)
21        5        16.24 [+ or -] 9.409 (a)
28        5        14.60 [+ or -] 15.237 (a)
42        5        12.57 [+ or -] 14.391 (a)
56        5         5.35 [+ or -] 3.601 (a)

Age      Cardiac gland region          Fundic gland region
(d)             mucosa                       mucosa

 0    21.13 [+ or -] 16.498 (ab)   18.32 [+ or -] 10.377 (ac)
 3    52.41 [+ or -] 16.556 (a)    39.02 [+ or -] 16.270 (a)
 7    49.27 [+ or -] 22.490 (ab)   55.60 [+ or -] 27.100 (abc)
14    29.80 [+ or -] 11.575 (ab)   21.80 [+ or -] 1.323 (ab)
21    12.61 [+ or -] 7.702 (b)      9.15 [+ or -] 3.867 (c)
28    23.28 [+ or -] 11.671 (ab)    8.57 [+ or -] 3.117 (c)
42     7.04 [+ or -] 3.041 (b)     10.79 [+ or -] 5.108 (bc)
56     5.22 [+ or -] 3.229 (b)      3.43 [+ or -] 3.327 (c)

Age      Pyloric gland region
(d)             mucosa

 0    37.94 [+ or -] 15.660 (ab)
 3    58.60 [+ or -] 28.920 (a)
 7    14.55 [+ or -] 1.328 (ab)
14    29.74 [+ or -] 18.168 (ab)
21     6.92 [+ or -] 5.440 (b)
28    11.89 [+ or -] 8.037 (ab)
42    10.23 [+ or -] 10.745 (b)
56     4.07 [+ or -] 4.910 (b)

* Statistics is Tukey'test under One-Way ANOVA in SPSS12.0.

Table 5. Developmental changes of abomasal pepsin (U/mg protein)

Age   Slaughter                                Cardiac gland region
(d)   number(n)           Contents                    mucosa

 0        6       0.008 [+ or -] 0.005 (a)   0.025 [+ or -] 0.005 (a)
 3        8       0.003 [+ or -] 0.001 (a)   0.025 [+ or -] 0.002 (a)
 7        5       0.003 [+ or -] 0.001 (a)   0.027 [+ or -] 0.003 (a)
14        5       0.004 [+ or -] 0.002 (a)   0.028 [+ or -] 0.003 (a)
21        5       0.005 [+ or -] 0.003 (a)   0.032 [+ or -] 0.006 (a)
28        5       0.005 [+ or -] 0.001 (a)   0.030 [+ or -] 0.004 (a)
42        5       0.009 [+ or -] 0.010 (a)   0.027 [+ or -] 0.002 (a)
56        5       0.006 [+ or -] 0.002 (a)   0.026 [+ or -] 0.004 (a)

Age     Fundic gland region        Pyloric gland region
(d)            mucosa                   mucosa

 0    0.027 [+ or -] 0.004 (a)   0.016 [+ or -] 0.002 (ab)
 3    0.031 [+ or -] 0.003 (a)   0.017 [+ or -] 0.003 (a)
 7    0.033 [+ or -] 0.004 (a)   0.013 [+ or -] 0.002 (ab)
14    0.034 [+ or -] 0.001 (a)   0.013 [+ or -] 0.004 (ab)
21    0.032 [+ or -] 0.006 (a)   0.011 [+ or -] 0.003 (ab)
28    0.030 [+ or -] 0.013 (a)   0.009 [+ or -] 0.001 (b)
42    0.029 [+ or -] 0.004 (a)   0.014 [+ or -] 0.008 (ab)
56    0.031 [+ or -] 0.003 (a)   0.013 [+ or -] 0.004 (ab)

* Statistics is Tukey'test under One-Way ANOVA in SPSS12.0.

Table 6. Developmental changes of abomasal pregastric esterase
(U/mg protein)

Age   Slaughter number(n)   Pregastric esterase activity
(d)

 0             6              0.083 [+ or -] 0.041 (a)
 3             8              0.034 [+ or -] 0.008 (a)
 7             5              0.037 [+ or -] 0.004 (a)
14             5              0.040 [+ or -] 0.010 (a)
21             5              0.036 [+ or -] 0.009 (a)
28             5              0.052 [+ or -] 0.013 (a)
42             5              0.057 [+ or -] 0.012 (a)
56             5              0.077 [+ or -] 0.019 (a)

* Statistics is Tukey'test under One-Way ANOVA in SPSS12.0.

Table 7. Developmental changes of pancreatic enzymes (U/mg protein)

Age   Slaughter        [alpha]-amylase
(d)   number(n)

 0        6       0.267 [+ or -] 0.016 (a)
 3        8       0.244 [+ or -] 0.018 (ab)
 7        5       0.249 [+ or -] 0.017 (ab)
14        5       0.259 [+ or -] 0.021 (a)
21        5       0.209 [+ or -] 0.037 (b)
28        5       0.261 [+ or -] 0.031 (a)
42        5       0.259 [+ or -] 0.015 (a)
56        5       0.248 [+ or -] 0.013 (ab)

Age           Lactase                     Lipase
(d)

 0    0.006 [+ or -] 0.002 (b)   0.041 [+ or -] 0.007 (a)
 3    0.010 [+ or -] 0.002 (a)   0.030 [+ or -] 0.004 (a)
 7    0.007 [+ or -] 0.001 (ab)  0.038 [+ or -] 0.010 (a)
14    0.010 [+ or -] 0.002 (ab)  0.039 [+ or -] 0.004 (a)
21    0.008 [+ or -] 0.002 (ab)  0.037 [+ or -] 0.010 (a)
28    0.010 [+ or -] 0.003 (ab)  0.038 [+ or -] 0.006 (a)
42    0.009 [+ or -] 0.002 (ab)  0.035 [+ or -] 0.009 (a)
56    0.010 [+ or -] 0.006 (ab)  0.037 [+ or -] 0.004 (a)

Age          Trypsinase                Chymotrypsin
(d)

 0    1.607 [+ or -] 0.317 (a)   0.105 [+ or -] 0.032 (b)
 3    1.475 [+ or -] 0.407 (a)   0.124 [+ or -] 0.031 (ab)
 7    1.325 [+ or -] 0.322 (a)   0.105 [+ or -] 0.012 (b)
14    1.644 [+ or -] 0.080 (a)   0.158 [+ or -] 0.032 (ab)
21    1.617 [+ or -] 0.129 (a)   0.157 [+ or -] 0.031 (ab)
28    1.534 [+ or -] 0.201 (a)   0.166 [+ or -] 0.028 (a)
42    1.556 [+ or -] 0.195 (a)   0.156 [+ or -] 0.024 (ab)
56    1.579 [+ or -] 0.121 (a)   0.156 [+ or -] 0.040 (ab)

* Statistics is Tukey'test under One-Way ANOVA in SPSS12.0.

Table 8. Development changes of plasma regulatory peptide
concentrations

Age   Slaughter                 CCK
(d)   number (n)             (pmol/L)

 0        6        28.128 [+ or -] 10.164 (ab)
 3        8        53.801 [+ or -] 17.396 (a)
 7        5        51.624 [+ or -] 26.714 (abc)
14        5        27.985 [+ or -] 25.671 (abc)
21        5        43.454 [+ or -] 32.693 (abc)
28        5        20.582 [+ or -] 20.512 (abc)
42        5         3.543 [+ or -] 2.799 (c)
56        5        10.032 [+ or -] 14.654 (b)

Age             Secretin                         PP
(d)              (ng/ml)                       (ng/ml)

 0    36.440 [+ or -] 14.221 (abc)    0.223 [+ or -] 0.057 (b)
 3    54.496 [+ or -] 7.731 (a)       0.308 [+ or -] 0.047 (ab)
 7    52.522 [+ or -] 9.701 (ab)      0.342 [+ or -] 0.024 (ab)
14    36.895 [+ or -] 14.235 (abc)    0.427 [+ or -] 0.068 (a)
21    43.970 [+ or -] 17.876 (abc)    0.403 [+ or -] 0.127 (ab)
28    31.282 [+ or -] 12.29 (bc)      0.440 [+ or -] 0.087 (ab)
42    24.820 [+ or -] 8.593 (c)       0.585 [+ or -] 0.347 (ab)
56    29.251 [+ or -] 8.349 (bc)      0.437 [+ or -] 0.098 (ab)

Age            Gastrin                        GIP
(d)            (ng/ml)                      (ng/ml)

 0     9.108 [+ or -] 1.921 (ab)   0.441 [+ or -] 0.125 (a)
 3    12.494 [+ or -] 1.873 (a)    0.425 [+ or -] 0.192 (a)
 7    11.872 [+ or -] 2.852 (ab)   0.467 [+ or -] 0.315 (ab)
14     7.051 [+ or -] 3.513 (ab)   0.167 [+ or -] 0.084 (ab)
21     9.724 [+ or -] 4.906 (ab)   0.161 [+ or -] 0.116 (ab)
28     6.300 [+ or -] 3.388 (ab)   0.068 [+ or -] 0.051 (b)
42     4.476 [+ or -] 2.093 (b)    0.043 [+ or -] 0.051 (b)
56     5.090 [+ or -] 2.320 (b)    0.062 [+ or -] 0.049 (b)

* Statistics is Tukey'test under One-Way ANOVA in SPSS12.0.

** CCK = Cholecystokinin; PP = Pancreatic polypeptide; GIP =
Gastric inhibitory peptide; same as following.

Table 9. Correlation between plasma regulatory peptide
concentrations and abomasal enzyme activities

                                       CCK      Secretin       PP

Chymosin     Cardiac gland region    0.633 **    0.530 **   -0.230
             Fundic gland region     0.616 **    0.570 **   -0.343 *
             Pyloric gland region    0.495 **    0.377 *    -0.438 **
Pepsin       Cardiac gland region   -0.061      -0.106       0.309 *
             Fundic gland region     0.064       0.201       0.234
             Pyloric gland region    0.217       0.199      -0.326 *
Pregastric   Contents               -0.346 *    -0.350 *     0.018
esterase

                                     Gastrin       GIP

Chymosin     Cardiac gland region    0.595 **    0.607 **
             Fundic gland region     0.598 **    0.691 **
             Pyloric gland region    0.500 **    0.676 **
Pepsin       Cardiac gland region   -0.153      -0.222
             Fundic gland region     0.089      -0.050
             Pyloric gland region    0.271       0.471 *
Pregastric   Contents               -0.345*     -0.200
esterase

* Statistics is Pearson in SPSS12.0.

Table 10. Correlation between plasma regulatory peptide
concentration and pancreatic enzyme activities

                    CCK      Secretin      PP      Gastrin       GIP

[alpha]-Amylase   -0.264     -0.298 *   0.048      -0.219     -0.065
Lactase           -0.305 *   -0.196     0.228      -0.294     -0.353 *
Lipase            -0.190     -0.238     0.221      -0.183     -0.194
Trypsinase         0.008      0.016     0.147      -0.008     -0.007
Chymotrypsin      -0.303 *   -0.307 *   0.514 **   -0.363 *   -0.532 **

* Statistics is Pearson in SPSS12.0.
COPYRIGHT 2011 Asian - Australasian Association of Animal Production Societies
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2011 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Xia, Lang; Cailian, Wang
Publication:Asian - Australasian Journal of Animal Sciences
Article Type:Report
Geographic Code:9CHIN
Date:Mar 12, 2011
Words:6789
Previous Article:Recycling of fermented sawdust-based oyster mushroom spent substrate as a feed supplement for postweaning calves.
Next Article:Evaluation of growth, carcass, immune response and stress parameters in naked neck chicken and their normal siblings under tropical winter and summer...
Topics:

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters