Body and intestinal growth of broiler chicks on a commercial starter diet. 2. Development and characteristics of intestinal enzymes

1. Investigations were conducted into the development of intestinal enzyme function in broiler chickens on a commercial starter diet. The differences between intestinal regions and localisation of enzymes on the villus were assessed. 2. The specific activity of maltase, sucrase, aminopeptidase N (APN) and alkaline phosphatase (AP) at all intestinal sites decreased with age. There were also variations between intestinal sites although this variation depended on age. The specific activity of maltase was higher than that of the other enzymes examined, regardless of age and intestinal site. The total activities of the enzymes also increased with age at all intestinal sites. 3. Results of the localisation of enzymes on the crypt: villus axis showed that activity was expressed over a large proportion of the villus. There was an increase in the total villus activity of alpha-glucosidase (AG), APN and AP with age. Activity per unit villus surface area was similar between ages, except for jejunal AP. At hatch enzyme activity was expressed over 44.1, 55.8 and 63.3% of villus height in the duodenum, jejunum and ileum, respectively. At 21 d of age, corresponding values were 68.7, 65.6 and 77.2%. The point of peak activity from the crypt: villus junction increased with age. In the jejunum, most enterocytes were capable of secreting active enzymes within 1 h of formation. Cells maintained their secretory capabilities until they were more than 60 h old in the case of AG. 4. Although the specific activities of the enzymes were maximal at hatch, the digestive capacity of older birds may be sustained by an increase in total enzyme activity brought about by increased surface area. The pattern of enzyme activity along the gastrointestional tract (GIT) and crypt: villus axis is similar to that reported for some mammalian species.     

Influence of supplementary fibrolytic enzymes on the fermentation of corn and grass silages by mixed ruminal microorganisms in vitro

This study was done to determine the effectiveness of supplementary enzymes at increasing the fiber digestion by ruminal microorganisms and to assess whether enzyme activity limits the rate of fiber digestion in ruminal digesta. In vitro comparisons of enzyme activities in two feed enzyme preparations (A and B) with enzyme activities extracted from ruminal fluid indicated that the addition of fibrolytic enzymes at the application rates recommended by the manufacturers would not be expected to increase significantly glycanase and polysaccharidase activities in ruminal fluid. Preparations A and B both increased (P < 0.001) the rate of gas production from freeze-dried corn and grass silages in in vitro incubations with ruminal fluid, but only at concentrations much higher than recommended application rates. Autoclaved controls had little or no effect. Ultrafiltration of enzyme B indicated that most stimulation was due to components >100 kDa, which is consistent with the cause of the stimulation being enzyme activity. Fibrolytic enzymes from other sources were also able to stimulate gas production: increased rates of gas production were observed in seven out of eight combinations of "cellulase" and corn or grass silage (P < 0.05). The comparison of glycanase and polysaccharidase activities with gas-stimulatory activity in the different enzyme preparations indicated that the highest correlation was between increased gas production and enzyme activity against microgranular cellulose (P < 0.05). In a wider range of fibrolytic enzyme preparations, those with endo-(beta-1,4)- or exo-(beta-1,4)-xylanase activity equal to that of preparation A did not produce similar increased rates of fermentation of corn silage when glucanase activity was low (P > 0.05). In contrast, preparations with glucanase activity similar to enzyme A gave at least as great (P < 0.05) an improvement in gas production than enzyme A, irrespective of xylanase activity. It was concluded that enzyme activity, probably a type of endo-(beta-1,4)-glucanase activity, limits the rate of fermentation of corn and grass silage in the rumen. Enzyme supplements of the type used in these experiments are unlikely to possess sufficient activity to overcome this limitation by direct application to ruminal digesta, implying that treatment of the ration prefeeding will be key to harnessing the potential of exogenous fibrolytic enzymes in ruminant nutrition.     

Activity of supplemental enzymes and their effect on nutrient utilization and growth performance of growing chickens as affected by pelleting temperature.

Activity of supplemental enzymes in a barley-soybean-maize based diet at 60, 75 and 90 degrees C pelleting temperatures was studied using feed viscosity, in-vitro enzyme activity and broiler performance data. High pelleting temperatures increased feed viscosity but supplemented enzymes reduced the viscosity at all three temperatures levels by 11, 14 and 17%, respectively. Water intake and losses in excreta of birds were found to be affected by feed viscosity. Activity of cellulase enzyme, measured using the radial diffusion method, was unaffected at 60 and 75 degrees C, but reduced by 73% in feed processed at 90 degrees C. Enzymes increased the weight gain of broilers by 11.1% at 90 degrees C, but no effect could be seen at low pelleting temperatures possibly due to high dietary protein and energy contents. Feed intake was unaffected by enzymes. Birds consumed 6% more feed and grew 9% faster when the pelleting temperature was increased from 60 to 75 degrees C. Reduced feed intake and daily weight gain observed at 90 degrees C could be fully compensated by the enzyme supplementation. High pelleting temperature reduced energy metabolizability (3.2%) and nitrogen utilization (4%) but enzyme almost compensated them (by 3.3% and 2.6%, respectively). No interaction could be detected between the pelleting temperatures and enzymes. It is concluded that pelleting temperatures as high as 90 degrees C drastically reduce cellulase activity, energy and nitrogen utilization thus lowering broiler performance. Either the remaining activity of cellulase or other thermostable enzymes can prevent the losses.     

Enzymatic antioxidant defense in isolated rat hepatocytes exposed to cadmium

The aim of the study was the evaluation of cadmium effects on the activity of antioxidant enzymes in rat hepatocytes. The studies were conducted with isolated rat hepatocytes incubated for 1 or 2 hours in a modified (deprived of carbonates with phosphates) Williams' E medium (MWE) in the presence of cadmium chloride (25, 50 and 200 microM). Hepatocytes incubated in the MWE medium without cadmium chloride were used as a control. The application of the modified Williams' E medium allowed for the appearance of cadmium compounds in a soluble form that is indispensable for suitable estimation of its toxic action. There were evaluated markers of the oxidative stress such as: concentration of thiobarbiturate reactive substances (TBARS)--proportional to the level of lipid peroxidation, concentration of reduced glutathione (GSH), and the activity of antioxidant enzymes, including superoxide dismutase (SOD1 and SOD2), catalase (CAT), total glutathione peroxidase (GSHPx), selenium--dependent glutathione peroxidase (SeGSHPx), glutathione transferase (GST) and glutathione reductase (GSHR). Alterations of antioxidant enzymes activity, the level of TBARS and GSH in isolated rat hepatocytes caused by cadmium in vitro, were shown to depend on the concentration and time of exposure of cells to this metal. The increased level of TBARS and GSH was observed as well as changes in the activity of antioxidant enzymes. The activity of SOD isoenzymes and CAT was increased, whereas GSHPx and GST were decreased. These results indicate that cadmium induces oxidative stress followed by alterations in the cellular antioxidant enzyme system in isolated rat hepatocytes.     

光周期与氮肥互作对华农1号青饲玉米碳氮代谢相关酶的影响

于2005年3-7月,采用盆栽试验,设置3个不同光照长度处理和氮素水平,研究了不同光照时数及氮素水平对远缘玉米杂交种华农1号青饲玉米碳氮代谢相关酶活性的影响.结果表明,在苗期,16 h光照处理下植株叶片磷酸烯醇式丙酮酸羧化酶、蔗糖磷酸合成酶、蔗糖合成酶、谷氨酰胺合成酶和硝酸还原酶等酶的活性显著低于13和10 h光照处理;至抽雄期和收获期,13和10 h处理下植株叶片各种酶的活性下降速率较快,而16 h处理下酶活性下降缓慢且显著高于13和10 h处理.在抽雄期或收获期,16 h处理下叶片各种酶的活性均随施氮量的增加而增加,但在13和10 h处理下均有几种酶的活性在高氮素水平下出现下降的趋势.总的看来,在16 h光照处理下,植株苗期碳氮代谢相对较弱,到中后期代谢能力明显提高,且耐高氮能力也较强,收获期植株叶片酶的活性显著高于13和10 h处理.     

不同饲料对中华倒刺鲤仔稚鱼消化酶活力的影响

采用生物化学的方法研究中华倒刺鲃仔稚鱼消化酶的个体发生和相互之间的异同.得到以下结果从胰蛋白酶活力来看.3个试验组之间具有显著性差异(P＜0.05),在试验后期,活饵组的胰蛋白酶活力大部分时间都大于饲料组.从淀粉酶活力来看,3个试验组都具有稳定上升的共同趋势,不过3个试验组之间仍旧具有显著性差异(P＜0.05).从脂肪酶活力来看,试验期间的变化规律都十分剧烈,其活力交替上升,3个试验组之间具有极显著性差异(P＜0.01).由此可见,不同饲料对于中华倒刺鳃仔鱼消化酶活力的影响十分巨大.     

Distribution of 5'-nucleotidase in the tissues of sheep and the effect of kidney and liver lesions on the activity of the enzyme in plasma and urine

The distribution of 5'-nucleotidase (5'-NT) activity in the tissues of the sheep differs from that of gamma glutamyl transferase (GGT). Nevertheless, both enzymes are released into the plasma of sheep which have been infected with Fasciola hepatica or in which the bile duct has been ligated. In a sheep dosed with sporidesmin, a fungal toxin which damages the biliary tract, there was an increase in GGT activity in the plasma and urine but no change in 5'-NT activity. Neither enzyme was released into the plasma or urine of sheep dosed with carbon tetrachloride. In sheep with renal tubular necrosis and hepatocellular necrosis caused by dosage with hexachlorobutadiene, both enzymes were released into the plasma, and GGT, but not 5'-NT activity was found in urine. In sheep with tubular necrosis of the kidney caused by the administration of mercuric chloride, GGT activity, but not 5'-NT, increased in the plasma and urine.     

Activity of superoxide dysmutase, catalase and glutathione peroxidase in rats exposed to chlorpyrifos and erofloxacin

The aim of the study was to investigate the influence of administration of chlorpyrifos and/or enrofloxacin on the activity of chosen antioxidative enzymes i.e.: superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in erythrocytes of rats. Chlorpyrifos was administered by stomach tube during 28 days at a dose of 3 mg/kg bw (0.02 LD50), and enrofloxacin was administered by stomach tube at a dose of 5 mg/kg bw during 3 subsequent days. It was stated that administration of enrofloxacin at applied dose did not cause any major changes in the activity of investigated antioxidative enzymes. The four-week exposure of rats to chlorpyrifos caused noticeable decrease in SOD and CAT activity in erythrocytes of rats at the beginning of the experiment (up to 24th hour) in comparison with the control group. The activity of GPx during all periods of the experiment was increased. In the group of animals in which both chlorpyrifos and enrofloxacin were applied, the profile of changes in activity of examined enzymes was similar to that one, which was observed after administration of chlorpyrifos exclusively, what may indicate lack of co-action between compounds used in the experiment.     

Influence of dietary zinc and copper on digestive enzyme activity and intestinal morphology in weaned pigs

The current study was conducted to investigate the effects of high dietary concentrations of Zn as zinc oxide and Cu as copper sulfate on the activity of digestive enzymes in the pancreas and the intestinal mucosa, intestinal morphology, and mucin histochemistry in pigs after weaning. Thirty-two pigs were weaned at 4 wk of age. The pigs were fed standard weaning diets supplemented with Zn (100 or 2,500 ppm) and Cu (0 or 175 ppm) in a 2 x 2 factorial arrangement of treatments for a 14-d period. In pancreatic tissue, the activity of amylase, carboxypeptidase A, chymotrypsin, trypsin, and lipase increased (P < 0.01) in pigs fed 2,500 ppm of Zn, whereas the activity of carboxypeptidase B and carboxylester hydrolase was unaffected. Copper had no effect on the activity of pancreatic enzymes. In small intestinal contents, the total activity of amylase and carboxypeptidase A was greater in pigs fed 100 ppm of Zn (P < 0.05), whereas feeding 2,500 ppm of Zn increased the chymotrypsin activity (P < 0.001). The remaining enzymes were unaffected by dietary Zn concentration. The villi were longer in the cranial small intestine (P < 0.001) in pigs fed 100 ppm of Zn than in pigs fed 2,500 ppm of Zn, but otherwise there were no clear effects of Zn and Cu supplementation on intestinal morphology. In the cranial small intestine, the activity of maltase (P < 0.001), sucrase (P < 0.001), and lactase was greater in pigs fed 100 ppm of Zn, even though there was a Zn x Cu interaction (P < 0.05) in lactase activity. In the middle and caudal small intestine, no clear differences between dietary treatments were observed. The activity of gamma-glutamyl transpeptidase in the intestinal mucosa was not affected by dietary Zn or Cu. In pigs fed 100 ppm of Zn, the activity of aminopeptidase N was greater in the caudal small intestine, but dietary Zn or Cu had no effect on aminopeptidase N in the cranial and middle small intestine. No effect of dietary Zn or Cu supplementation was found on carbohydrate histochemistry in the caudal small intestine, whereas high dietary Zn increased the area of neutral, acidic, and sulfomucins in the cecum (P < 0.01) and in the colon (P < 0.001). In summary, high dietary Zn increased the activity of several enzymes in the pancreatic tissue and increased the mucin staining area in the large intestine, whereas Cu had no clear effect on these variables. However, no definite answers were found as to how the growth promoting and diarrhea reducing effects of excess dietary Zn are exerted.     

Serum enzyme changes in newborn calves fed colostrum

In 10 newborn Holstein calves, which were initially bottle-fed on pooled colostrum, there were transient increases in several serum enzymes. Within a few hours, the mean serum gamma-glutamyl transferase (gammaGT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), acid phosphatase (ACP), and lactate dehydrogenase (LDH) activities increased 62.5, 2.4, 2.0, 1.8 and 1.3 fold, respectively. In two other calves given initial feeds of enzyme-free pasteurized milk, there were similar increases in serum enzymes, except serum gammaGT. Correct interpretation of serum enzyme activities in newborn calves must take into account the normal increases which occur after feeding colostrum. Serum gammaGT was the only enzyme to increase markedly as a result of its absorption from colostrum. The other serum enzymes are presumably released from the tissues of the calf. The increased activities of serum CK observed in some newborn calves probably resulted from trauma during birth or increased muscular activity after birth.     

The postnatal development of drug-metabolizing enzymes in hepatic, pulmonary and renal tissues of the goat

It is important to study the development of drug biotransformation enzymes, because from a pharmacological and therapeutic point of view these enzymes are responsible for eliminating most drugs. Their concentration at each age is critical when deciding the dose regimen, particularly in the neonates who are deficient or have very low levels of these enzymes. From a toxicological perspective, the role of these enzymes varies, with some of them being directly responsible for activation of certain chemicals to reactive intermediates with deleterious consequences to the animal. The time course of appearance of these enzymes throughout the life of the animal could be depicted from the study of their ontogeny and therefore the prediction of when the animal would be at risk should be possible. Experiments were designed to measure in vitro , the activity of drug-metabolizing enzymes in liver, lung and kidney of newborn, 1-week-, 4-week and 6-week-old and adult goats. The microsomal mono-oxygenase activities were measured utilizing substrates designed to characterize the development of the cytochrome P450 (P450). For phase II enzymes, the activity of UDP-glucuronyltransferase towards 1-naphthol and p-nitrophenol was measured in addition to the cytosolic glutathione S-transferase activity towards, 1,2-dichloro 3-nitrobenzene. The results indicated that the newborn goat tissues exhibited very low activity of drug-metabolizing capacity in all pathways studied. These activities increased to the adult values by 6 weeks of age. In general, the development of the mono-oxygenase activities followed the same pattern as the overall P450. The UDP-glucuronyltransferase activity towards both substrates was deficient at birth and surged to above adult values by the first week of age. The toxicologic and pharmacologic implications of the development of these enzyme activities are discussed.     

Effect of age, weaning and diet on digestive enzyme levels in the piglet

Thirty-seven pigs were used to evaluate the effects of age and weaning on the level of protease in the gastric mucosa and trypsin, chymotrypsin, amylase and lipase in the pancreas. There was a positive allometry of the pancreas and gastric mucosa associated with age and with weaning to a solid diet. Increases with age in total activity of chymotrypsin, trypsin, amylase and gastric proteases were due to increases in both tissue weight and enzyme activity per gram of tissue. A general depression in pancreatic enzymatic activities, but not in gastric proteolytic activity, was found during the first week following weaning. Forty pigs were used in a second trial to evaluate the effects of age and weaning diet on the same digestive enzymes. Total activity of all enzymes assayed increased with time postweaning. Increases in total activity of lipase and chymotrypsin were due primarily to increased pancreatic weight postweaning. Amylase, trypsin and gastric protease increases were due both to increased tissue weight and increased activity per gram of tissue. There were no effects of diet on the weight of gastric mucosa or the level of activity of the gastric proteases. Pigs fed a diet containing 20% whey had larger pancreases (P less than .10) at slaughter and a greater, but nonsignificant, mean activity per gram of pancreas for all pancreatic enzymes. It appears that the pig has sufficient pancreatic and gastric enzyme activity so that performance should not be limited, with the possible exception of the period shortly after weaning. However diet digestibility and subsequent pig performance may be more directly related to the extent of release of these enzymes into the intestine and the conditions that exist therein.     

Marek's disease vaccination, with turkey herpesvirus, and enrofloxacin modulate the activities of hepatic microsomal enzymes in broiler chickens

Chickens were vaccinated against Marek's disease intramuscularly at one day of age. Enrofloxacin was given ad libitum in the drinking water at concentrations of 50, 100 and 250 mg/L from 8 days to 13 days of age when the animals were killed and the activities of cytochrome P-450 enzymes in the liver were measured. Vaccinated non-treated chickens served as a positive control. A negative control group was neither vaccinated nor treated. Vaccination decreased the activity of aniline hydroxylase and ethylmorphine N-demethylase in the positive control group. Subsequent application of enrofloxacin in the lowest concentration (50 mg/L) decreased, while that given at the highest level (250 mg/L) significantly increased the activity of the same microsomal enzymes. Relative liver weights and concentrations of proteins in 9000 x g supernatant were not affected by vaccination or treatment.     

滞育发动前家蚕滞育性与非滞育性卵的谷胱甘肽氧化还原循环状态分析

为了调查滞育和非滞育性家蚕卵的谷胱甘肽氧化还原循环在滞育发动前是否存在差异,利用分光光度法检测滞育发动前(25℃中蚕卵产下后0～24 h)滞育与非滞育蚕卵的谷胱甘肽含量和相关代谢酶活性。滞育发动前,滞育性家蚕卵中的还原型谷胱甘肽(GSH)含量、氧化型谷胱甘肽(GSSG)含量、总谷胱甘肽(GSH+2GSSG)含量和GSH/GSSG比值变化不显著,谷胱甘肽S-转移酶(GST)活性变化不显著,但硫氧还蛋白过氧化物酶(TPX)活性下降23%,谷胱甘肽还原酶(GR)活性升高57%;非滞育性家蚕卵中的GSH含量及TPX和GST活性变化不显著,但GSSG含量升高61%,GSH+2GSSG含量升高41%,GSH/GSSG比值下降33%,GR活性下降16%。与非滞育性家蚕卵相比,滞育发动前滞育性家蚕卵中的GSH含量、GSSG含量和GSH+2GSSG含量较低,GSH/GSSG比值较高,TPX活性较低,GST活性无显著差异,GR活性较高。两种蚕卵中都未能检测到谷胱甘肽过氧化物酶(GPX)和硫氧还蛋白还原酶(TrxR)活性。结果表明,滞育发动前滞育性家蚕卵中较低的TPX活性和较高的GR活性共同导致较高的GSH/GSSG比值,使其谷胱甘肽氧化还原循环处于相对还原态。     

马立克氏病乌黑鸡群血清学研究

对４月龄感染了马立克氏病的２月龄－６月龄乌黑鸡群血清蛋白及血清酶的研究结果表明;２月龄～３月龄健康乌黑鸡如血清蛋白升高极显著（Ｐ〈０．０１）,血清ＡＬＰ活性下降显著（Ｐ〈０．０５）,ＡＭＳ活性下降不明显（Ｐ〉０．０５）,ＣＨＥ活性升高不明显（Ｐ〉０．０５）,４月龄感染ＭＤ后,血清蛋白显著降低（Ｐ〈０．０５）,而后,白脓月回升,变化均不明显（Ｐ〉０．０５）,白蛋白在５月龄再次极显著降低（Ｐ〈０．０５     

Enzyme arrangement of various tissues in swine. 3. Studies of pre- and postnatal activities of various enzymes (ATPase, GOT, GPT, leucine aminopeptidase, acid and alkaline phosphatases, aldose reductase, glucuronate reductase, sorbitol dehydrogenase) in various tissues]

The crude protein levels as well as the activities of various enzymes were studied in certain tissues of fetuses (80th through 114th days of development), piglets of different age groups, and pigs for slaughter. In most of the tissues tested the postnatal activities of Na-K-ATPase were beyond those recorded from fetuses. The highest GOT activities were recorded from the liver, myocardium, and kidneys. Activities were found to rise sizeably in some tissues after birth. The activity of GPT, too, exhibited age-dependent variations. The activity of leucine-aminopeptidase increased strongly after birth in liver and kidneys. Acid phosphatase activity was less markedly influenced by development phases. Those enzymes which are involved in the formation of fructose and glucose (aldolreductase, glucuronate-reductase, and sorbite-dehydrogenase) had their highest activities, all age-dependent, in liver and kidneys.     

Relationship between oxidative stress and clinical-pathological aspects in dogs experimentally infected with Rangelia vitalii

The aim of this study was to evaluate lipid peroxidation, protein oxidation and activity of enzymes that are indicators of oxidative stress in Rangelia vitalii infection in dogs. Animals were divided into two groups: negative control (n=5) and infected with R. vitalii (n=7). After inoculation, the parasitemia was estimated daily by microscopic examination of smears. Lipid peroxidation (TBARS) and advanced oxidation protein products (AOPP); and delta-aminolevulinate dehydratase (δ-ALA-D), superoxide dismutase (SOD) and catalase (CAT) activities in blood were evaluated. The samples were collected at days 10 and 20 post-inoculation (PI). TBARS and AOPP levels were higher in the infected group in both analyzed periods (P<0.01). The δ-ALA-D activity was reduced in blood of dogs infected with R. vitalii on days 10 and 20 PI. SOD activity was significantly increased (P<0.01) in the blood of dogs infected with R. vitalii at days 10 and 20 PI, while CAT activity was significantly increased (P<0.01) only at day 20 PI when compared to non-infected animals. A positive correlation was observed between the degree of parasitemia and TBARS and AOPP levels and activity of antioxidant enzymes. The δ-ALA-D activity was negatively correlated with the degree of parasitemia. Based on the increased levels of TBARS, AOPP, SOD and CAT activities, and inhibition δ-ALA-D activity, we concluded that dogs experimentally infected with R. vitalii develop a state of redox unbalance and that these changes might be involved in the pathophysiology of disease.     

The thermostability of proteases from virulent and benign strains of Bacteroides nodosus

Protease enzymes, produced by Bacteroides nodosus strains isolated from animals with virulent and benign forms of ovine footrot, were partially purified by ultra-filtration, ion exchange chromatography and gel permeation chromatography. Each enzyme had a similar pH optimum, was inhibited by phenylmethylsulfonyl fluoride (PMSF), ethylene diamine tetraacetic acid (EDTA) and ethyleneglycot-bis-aminoethylether-N,N-tetraacetic acid (EGTA), but was not inhibited by 1,10-phenanthroline. The results suggest that these enzymes are serine proteases that require divalent cations for activity. The enzymes could be distinguished by their differential temperature stability and differing susceptibility to irreversible inactivation by EDTA. Both enzymes were stabilised by incubation in the presence of Ca2+, but the enzyme purified from the virulent isolate required less Ca2+ for maximum stability. These results suggest that the differential thermostability of the protease activity detected in virulence tests is an intrinsic property of the protease enzymes.     

添加外源性酶对猪、鸡内源消化酶活性的影响

观察了猪、鸡不同类型饲粮中添加外源性酶制剂后对其内源性消化酶活性的影响。结果,玉米－豆粕型饲粮中添加外源酶后,３７及６７日龄丝毛乌骨鸡的小肠胰蛋白酶活性分别提高１３．１５％（Ｐ＜０．０５）和９．４５％（Ｐ＜０．０５）,总蛋白水解酶活性提高７．３０％（Ｐ＞０．０５）和１３．７％（Ｐ＜０．０５）,但α－淀粉酶活性无显著变化;高麸皮饲粮中添加外源酶可使４９日龄ＡＡ肉鸡的胰蛋白酶,总蛋白水解酶和α－淀粉酶活性分别提高４６．５０％（Ｐ＜０．０５）,１５．２０％（Ｐ＞０．０５）和７９．８０％（Ｐ＜０．０５）,而对胰脏中α－淀粉酶、脂肪酶活性无显著影响;高次粉饲粮中添加外源酶可使杜长大仔猪的小肠总蛋白水解酶活性提高２１．００％（Ｐ＜０．０５）,而对肠α－淀粉酶活性无显著影响;大麦－豆粕型饲粮中添加外源酶可使杜长大肥育猪的肠胰蛋白酶活性下降３６．９０％（Ｐ＜０．０５）,肠脂肪酶活性提高７２．７％（Ｐ＜０．０５）,而对小肠α－淀粉酶和胰脏α－淀粉酶、脂肪酶活性无显著影响。据此认为,外源性酶与畜禽内源性消化酶活性的关系较为复杂,受到动物品种和饲粮类型的影响,尤其是后者。