Temporal changes in carbohydrate digestive capacity and growth rate of piglets in response to glucocorticoid administration and weaning age

Two experiments were conducted that demonstrated that a single injection of hydrocortisone 21-acetate (HYD, 25 mg/kg BW) administered to 6-d-old nursing piglets resulted in a twofold elevation (P less than .02) of pancreatic amylase within 2 d; activity was unaffected by an injection of 15 IU adrenocorticotropic hormone (ACTH)/kg BW (P greater than .20). Intestinal sucrase and maltase activity tended to be elevated (P less than .20) 2 and 4 d postinjection with HYD but returned to normal (uninjected) levels by 14 d of age. The normal decline of intestinal lactase activity was delayed by at least 4 d in response to both hormones (P less than .10). Organ weights were not affected by either hormone. In a separate experiment, postweaning mortality was reduced (12 vs 27%) and growth rate was substantially improved by administration of HYD to piglets 4 and 2 d prior to weaning at 14 d of age. Hydrocortisone resulted in a faster rate of gain the 1st wk postweaning for pigs weaned at 21 or 28 d. Subsequent gain by control and HYD piglets weaned on d 21 was similar, but HYD subsequently impaired growth rate of piglets weaned at 28 d of age. Growth rates of control and ACTH piglets were similar at each postweaning period regardless of weaning age (weaning age [lin.] x week postweaning [quad.] x treatment, P less than .07). This differential treatment response of daily gain may be due in part to effects on feed intake (weaning age [lin.] x week postweaning [lin.] x treatment, P less than .10). We conclude that a single injection of HYD to 6-d-old piglets precociously induces pancreatic amylase and that the sensitivity of piglets to HYD is age-dependent.     

Effects of dietary changes on the antibacterial activity of pancreatic juice in weaned piglets

At weaning, low feed intake level is a major factor responsible for gut disorders. However, less is known on adaptation of the antibacterial activity of pancreatic juice in response to variations in feed intake level. Moreover bovine colostrum has been demonstrated to decrease coliform counts in duodenal digesta and to improve health status of weaned piglets. Aims of the present study were to evaluate effects of feed intake level and of a bovine colostrum-supplemented diet on the pancreatic secretion of antibacterial activity in piglets at weaning. At 33 days of age, twenty-eight piglets fitted with two permanent catheters (for pancreatic juice collection and reintroduction) were weaned and allocated to one of the following three dietary treatments for 5 days: low feed allocation with a starter diet (L), gradually increased feed allocation with a starter diet (Ctrl), or gradually increased feed allocation with a starter diet supplemented with bovine colostrum (Col). In Ctrl piglets, the post-weaning secretion of antibacterial activity did not significantly differed from pre-weaning values. The pancreatic secretion of antibacterial activity in L piglets was higher than that in Ctrl piglets at day 5 (+ 300%; P < 0.05). Moreover in Col piglets the secretion of the antibacterial activity tended to increase by 55% (P = 0.08) compared to Ctrl piglets. Variations in the pancreatic secretion of antibacterial activity could constitute an adaptive phenomenon to maintain bacterial homeostasis in the upper small intestine during the early post-weaning period.     

超早期断奶应激对仔猪消化酶活性的影响初报

试验选用两窝１４ 日龄杜×（ 大×长） 三元杂交商品猪,每窝１０ 头,每窝仔猪按体重平均分为断奶处理组和哺乳对照组,每组两个重复（ 栏） ,每栏５ 头猪。分别于断奶后第０（１４ 日龄） 、２ 、４ 、６ 、９ 天从每栏内随机抽取一头猪,屠宰后取胰腺和空肠内容物样品,测定胰蛋白酶、淀粉酶及脂肪酶活性。试验结果表明,断奶应激不同程度地降低了仔猪胰腺和空肠内容物中胰蛋白酶、淀粉酶和脂肪酶活性。随着断奶后时间的推移和采食量的增加,断奶仔猪空肠内容物中胰蛋白酶、脂肪酶以及胰腺中淀粉酶活性得以恢复并呈上升趋势。     

The effect of feeding time (day versus night) and feeding frequency on pancreatic exocrine secretion in pigs

The effect of night feeding and feeding frequency on exocrine pancreatic secretion was studied in five chronically catherized growing pigs (16 to 31 kg). Feeding during the night (2200 to 2400 h) as compared to the day (1000 to 1200 h) tended to stimulate cholesterol ester lipase activity and tended to lower the colipase : lipase ratio in the pancreatic juice, but no effect on volume output, protein output and the activities of trypsin, chymotrypsin, amylase, lipase and colipase could be demonstrated. Feeding 12 small meals between 0800 and 2000 h as compared to one large meal (1000 to 1200 h) daily, altered the pattern of exocrine pancreatic secretion, tended to stimulate protein output by 44 %, chymotrypsin activity by 29 % and lipase activity by 46 %. These observations strengthened the theory that exocrine pancreatic secretion is partly regulated by feed intake per se and does not only depend on the amount of feed consumed. Feeding 12 small meals versus one large meal, compared at the same total daily feed intake, lowered the colipase : lipase ratio by 32 %. It can be concluded that feed intake pattern affected exocrine pancreatic secretion.     

Effect of creep feed consumption on individual feed intake characteristics and performance of group-housed weanling pigs

To assess the effects of creep feed consumption on individual feed intake characteristics and performance of group-housed weaned pigs, 16 litters (149 piglets) were fed a commercial creep feed (3,040 kcal NE/kg, 15.2 g lysine/kg) supplemented with 1% chromic oxide. Another five litters (48 piglets) were not given access to creep feed (no-feed). Piglets were weaned at 28 d after birth. On d 18, 22, and 27 of age, fecal samples from all the piglets were taken using fecal loops. A green color of the feces indicated that the piglet had eaten creep feed. Piglets that had green-colored feces three times were considered as eaters. Piglets that never showed green-colored feces were considered as non-eaters. At weaning 22 piglets of each type (no-feed, non-eaters, and eaters) were selected based on BW, litter origin, and sex. These 66 pigs were assigned to six pens equipped with computerized feeding stations. Eaters, non-eaters, and no-feed pigs were equally divided over all six pens. After weaning a prestarter (d 0 to 13) and a starter diet (d 14 to 34) were offered for ad libitum consumption. The individual feed intake characteristics of latency time (interval between weaning and first feed intake) and initial feed intake (intake during the first 24 h following first feed intake) and performance traits were determined for all piglets. The pigs that were designated as eaters needed less time between weaning and first feed intake than the pigs that were designated as non-eaters and no-feed pigs (P = 0.04 and P = 0.06, respectively). Initial feed intake was not affected (P > 0.1) by feed intake prior to weaning. However, during d 0 to 8 the eaters had more visits per day during which feed was consumed than both the non-eaters and no-feed pigs. Averaged over the first 8 d after weaning, the ADFI and ADG of the eaters were higher than that of the non-eaters and no-feed pigs (P < 0.05). Averaged over the total 34-d period the effect of creep feed intake on postweaning ADFI was much less pronounced (P = 0.20), whereas ADG of the eaters was the highest (P < 0.05). Creep feed intake during the sucking period stimulates early postweaning feed intake as well as postweaning performance.     

Impaired pancreatic endocrine and exocrine responses in growth-retarded piglets

The alteration of pancreatic endocrine and exocrine secretory responses induced by secretagogues and neural input was investigated in post-weaning growth-retarded (GR) piglets. Blood and pancreatic juice were collected from these animals (6-8-weeks old). Plasma insulin and pancreatic digestive enzymes induced by nutrients, drugs and vagal stimulation were measured biochemically. The pancreas was inspected by immunohistochemical analysis. In GR piglets, the plasma glucose and insulin concentrations at the resting state were very low, and the secretory response was also markedly reduced, with maximum inhibition of 90% by glucose administration and 83% by arginine administration. The insulin secretion was not increased by 2-deoxy-D-glucose administration in GR piglets. The pancreatic juice secretions induced by vagal stimulation and secretagogues in GR piglets were not different from those induced in the control piglets. However, amylase activity in the pancreatic juice and in the pancreas was significantly decreased in GR piglets, although trypsin and chymotrypsin activities were not different. In the immunohistochemical analysis, the numbers of islets and the staining degree for insulin antibody also declined in the pancreases of GR piglets. These results indicated the reduction of insulin and amylase secretions from the pancreas in GR piglets, suggesting that a dysfunction of pancreatic endocrine and exocrine secretion during growth after weaning may be an important factor in the induction of growth retardation in piglets.     

Effects of sweeteners on individual feed intake characteristics and performance in group-housed weanling pigs

To assess the effects of 2 high intensity sodium saccharine-based sweeteners on individual feed intake characteristics and performance of group-housed weaned pigs, one hundred ninety-eight 26-d-old weanling pigs were given ad libitum access to 3 dietary treatments containing: no additional sweetener (control), 150 mg of sweetener (Sucram C-150)/kg, or 150 mg of sweetener (Sucram 3D)/kg. At weaning, piglets were allocated to 18 pens (11 pigs/pen) based on BW, sex, and ancestry, and pens were randomly assigned to 3 treatments with 6 pens per treatment. The pens were equipped with computerized feeding stations. During the first 12 d, pigs were offered pelleted prestarter diets that were replaced at once by pelleted starter diets for the last 7 d of the 19-d experimental period. The individual feed intake characteristics consisting of latency time (interval between weaning and first feed intake), initial feed intake (intake during the first 24 h following the first feed intake), the number of total visits per day, and the number of visits in which feed was consumed, together with the time and the feed intake per visit, were determined for all piglets. Performance traits and fecal consistency were determined per pen for d 0 to 5, d 5 to 12, and d 12 to 19, as well as for the total period (d 0 to 19). The initiation of feed intake was not affected by the addition of high intensity sweeteners to the diet. From 12 d postweaning, dietary sweeteners caused the piglets to focus more on feed intake and less on exploratory behavior, as shown by the increased percentage of visits with feed intake in pigs fed the Sucram 3D diet compared with those fed the control diet (P = 0.002). The overall daily feed intake increased with time but was not affected by the addition of sweeteners. Nevertheless, dietary sweeteners prevented the depression of feed intake on d 8 and 10 postweaning (d 8, P = 0.013; d 10, P = 0.014), which seemed to coincide with an improved fecal consistency score (d 5 to 12, P = 0.11; d 12 to 19, P < 0.001). However, the changes in feed intake characteristics and fecal consistency only resulted in numerical effects on postweaning pig performance (ADFI, P = 0.126; ADG, P = 0.140). The results of the present study indicate that weanling pigs need a certain period of time before clear effects of dietary sweeteners on individual feed intake characteristics and pig performance can be observed.     

3周龄断奶仔猪胰酶发育规律的研究

以 3周龄断奶仔猪为试验材料 ,研究了断奶对仔猪胰酶活性的影响。试验表明 ,3周龄断奶可以显著降低仔猪胰脏中胰淀粉酶、胰蛋白酶、胰糜蛋白酶和胰脂肪酶的活性 ,且在断奶后 2周继续维持断奶时水平。断奶降低了小肠内容物中胰淀粉酶和胰脂肪酶的活性 ,但空肠和回肠胰蛋白酶、胰糜蛋白酶的活性在断奶后并未下降。     

Attempt to establish a chronic model to study the influence of bile and pancreatic juice diversion on pancreas feedback regulation in conscious pigs

The diversion of pancreatic juice and bile stimulates pancreatic exocrine secretion but the mechanism behind this process is still not clear. The present study investigates the influence of long lasting (10 h) bile diversion or pancreatic juice and bile diversion on the pancreatic secretion in conscious pigs. The experiments were performed on 4 weaned piglets, which had a catheter inserted to the accessory pancreatic duct and bile duct and two cannulas to the duodenum. The depletion of bile alone or both bile and pancreatic juice (PJ) resulted in an increased preprandial pancreatic juice outflow, as compared to controls. Bile diversion increased the pancreatic response to feeding. PJ volume, protein outflow, and trypsin activity values were significantly higher in bile diverted pigs than in control pigs during the prandial and postprandial periods. While in pancreatic juice and bile diverted piglets the PJ protein outflow and trypsin activity slightly increased in response to feeding, their values were lower than those of the control piglets. In conclusion, both pancreatic juice and bile present in the small intestine play an important role in the regulation of the pancreatic juice secretion.     

发酵豆粕对断奶仔猪生长性能、消化酶及肠道菌群结构的影响

【目的】本试验旨在探讨发酵豆粕(FSBM)对断奶仔猪生长性能、消化酶活性及肠道菌群结构的影响。【方法】试验选取48头21日龄断奶仔猪(杜×长×大,6.88 kg±0.13 kg),随机分为对照组和试验组,每组4个重复,每个重复6头猪。对照组饲粮为基础饲粮,试验饲粮用6%FSBM等量替代基础饲粮中的豆粕。试验期为20 d。试验期间记录采食量和体重。试验第21天,每个重复选取2头猪屠宰,收集回肠食糜测定消化酶活性和肠道菌群结构,并对两者进行相关性分析。【结果】(1)饲喂FSBM可显著提高断奶仔猪的终末体重和平均日增重(average daily gain, ADG),并显著降低了料重比(feed/gain, F/G)(P<0.05);(2)FSBM组断奶仔猪回肠中的胰蛋白酶和淀粉酶活性显著提高(P<0.05);(3)饲喂FSBM显著提高了断奶仔猪回肠食糜中拟杆菌门、普雷沃氏菌科NK3B31类群、厌氧弧菌属、瘤胃菌科UCG-005、普氏菌属2、巨型球菌属、副杆菌属、Solobacterium及毛螺菌科UCG-004的相对丰度,显著降低了链球菌属的相对丰度(P<0.05);(...     

Effects of restricted feeding of beef heifers during the postweaning period on growth, efficiency, and ultrasound carcass characteristics

Traits used for identification of replacement beef heifers and feeding levels provided during postweaning development may have major financial implications due to effects on maintenance requirements and level of lifetime production. The current study evaluated the effects of 2 levels of feeding during the postweaning period on growth, G:F, and ultrasound carcass measurements of heifers, and the associations among these traits. Heifers (1/2 Red Angus, 1/4 Charolais, and 1/4 Tarentaise) born in 3 yr were randomly assigned to a control (fed to appetite; n = 205) or restricted (fed at 80% of that consumed by controls adjusted to a common BW basis; n = 192) feeding during a 140-d postweaning period. Heifers were individually fed a diet of 68% corn silage, 18% alfalfa, and protein-mineral supplement (DM basis) in pens equipped with Calan gates. Ultrasound measurements of LM area, intramuscular fat, and subcutaneous fat thickness over the LM were made on d 140 (382 +/- 0.8 d of age). Average daily DMI was 4.1 and 5.6 kg/d for restricted and control heifers, respectively (P < 0.001). Feed restriction decreased (P < 0.001) BW (292 vs. 314 kg), ADG (0.52 vs. 0.65 kg/d), LM area (55 vs. 59 cm2), intramuscular fat (3.2 vs. 3.5%), and subcutaneous fat thickness over the LM (3.2 vs. 3.9 mm), but increased G:F (0.12 vs. 0.11) when compared with control at the end of the 140-d study. The magnitude of the associations of DMI with ADG (r = 0.32 vs. 0.21), 140-d BW (r = 0.78 vs. 0.36), hip height (r = 0.57 vs. 0.17), LMA (r = 0.30 vs. 0.18), and BCS (r = 0.17 vs. 0.11) was greater in restricted- than control-fed heifers. Variance of residual feed intake, calculated within each treatment, was greater (P < 0.01) in control (0.088) than restricted (0.004) heifers, and magnitude of association between residual feed intake and average DMI was greater in control (r = 0.88) than restricted (r = 0.41) heifers. Pregnancy rate tended (P = 0.11) to be reduced in heifers that had been developed on restricted feeding (86.3 +/- 2.3 vs. 91.5 +/- 2.3%). However, ADG was greater (P < 0.001) in restricted than control heifers (0.51 vs. 0.46 kg/d) while grazing native range in the 7 mo after restriction. In summary, restricted heifers consumed 22% less feed on a per-pregnant-heifer basis during the development period and had a greater magnitude of association between DMI and several growth-related traits at the end of the 140-d postweaning feeding period, which is indicative of improved efficiency.     

Efficacy of initial postweaning diet and supplemental coconut oil or soybean oil for weanling swine

Two experiments involving a total of 581 crossbred pigs weaned at 23 +/- 2 d of age evaluated 1) the efficacy of two diets that contained milk products during the initial 14 d postweaning and 2) the effect of coconut oil or soybean oil additions to swine starter diets. In Exp. 1, postweaning performance responses of pigs fed a control corn-soybean meal-dried whey (C-SBM-DW) diet without added fat were compared with those of pigs consuming diets that contained 3, 6, or 9% levels of coconut oil or degummed soybean oil. The results demonstrated no beneficial weight gain, feed intake, or gain-to-feed ratio response during the initial 14 d postweaning to either dietary oil source. From 15 to 35 d, gains increased to the 6% added fat level, but there was no effect on feed intake when the gain-to-feed ratio was improved to the 9% fat level. In Exp. 2, two diets containing milk products were fed during the initial 14-d postweaning period. The first diet contained corn, soybean meal, dried whey, dried skim milk, and fishmeal (high nutrient dense diet, HNDD), and the second was a C-SBM diet with 25% dried whey. During the period from 15 to 35 d, diets contained no added fat or a 6% level of coconut oil, soybean oil, or the 1:1 combination of each at 3%. The results demonstrated that for the postweaning period from 0 to 14 d pigs fed the HNDD had higher gains (P less than .01), feed intakes (P less than .01), and gain-to-feed ratios (P less than .01) than pigs fed the C-SBM-DW diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impact of energy intake and pregnancy status on rate and efficiency of gain and backfat changes of sows postweaning

A collaborative study was conducted to evaluate factors related to determining optimal feeding and management programs for increasing net returns from marketing cull sows. A total of 269 multiparous sows averaging 192 kg of body weight were weaned, moved to individual gestation crates, and assigned to one of eight treatment combinations in a 2 x 2 x 2 factorial arrangement for a 42-d postweaning feeding experiment. Factors included limited (L) (1.8 kg/sow/d) or ad libitum (AL) access to feed during wk 1 postweaning, a corn-soybean meal (corn) or barley-sunflower meal (barley) diet, and pregnant or nonpregnant status. All sows were provided ad libitum access to feed from wk 2 to 6 postweaning. Gain and feed intake (FI) data were collected weekly for each sow and used to calculate gain:feed (G/F). Ultrasonic backfat (BF) data were collected on d 0, 21, and 42 postweaning. Sows on the AL treatment had greater FI (P < 0.05) but similar gain (P = 0.80) for the 42-d postweaning period compared to sows on the L treatment. Most of this response was due to lower sow body weight loss during wk 1 postweaning (P < 0.01) when sows were provided AL (-7.2 kg) vs L (-13.2 kg) access to feed. Sows fed the corn diet had higher gain (P < 0.01), improved G/F (P < 0.01), and increased BF (P < 0.01) over the 42-d feeding period than sows fed barley. The corn diet resulted in less sow BW loss (P < 0.01) during wk 1 (-8.8 kg) than the barley diet (-11.6 kg). Pregnant sows had higher gain, FI, G/ F, and BF (P < 0.01) than nonpregnant sows over the 42-d feeding period. Most of this advantage occurred during wk 4 postweaning when FI and gain of nonpregnant sows was lower (P < 0.01) than for pregnant sows. An economic analysis indicated that, when cull sow prices are relatively high and feed prices are moderate to low, maintaining and managing cull sows for an additional 6 wk postweaning may be economically advantageous compared to 0 or 3 wk. Pregnant sows fed the corn diet produced the greatest economic return. These results suggest that mating sows as they return to estrus postweaning and providing ad libitum access to a corn-soybean meal diet improves growth performance and feed efficiency, and may thereby provide increased returns when marketing cull sows.     

The effect of meal intervals and weaning on feed intake of early weaned pigs

Feed intake was investigated in early weaned pigs housed in two environments. In the first experiment, pigs in an unfamiliar environment (removed from the sow and placed in nursery pens) were offered a dry diet either ad libitum or at different meal intervals (2, 4 and 6 h). Regardless of meal interval (ad libitum or hourly intervals), early weaned (21 d) pigs failed to consume sufficient feed for maintenance during the first 3 d postweaning. Pigs provided feed ad libitum consumed more (P less than .001) feed (142 vs 84 g/d) and gained more (P less than .05) weight (57 vs 3 g/d) than meal-fed pigs over the 7-d period. Pigs fed at 2-h intervals consumed more (P less than .001) feed than pigs fed at 4-h or 6-h intervals. Compared with preweaning levels (307 mu eq/liter), plasma free fatty acid (FFA) levels increased approximately fourfold by d 1 postweaning (1,372 mu eq/liter), then decreased through d 7 to levels below preweaning (142 mu eq/liter). The FFA levels were not affected (P greater than .1) by meal interval. In a second experiment, feed intake was investigated in weaned pigs that were allowed to consume food by a familiar method and in a familiar environment (suckling the sow). When allowed to nurse following a 24-h weaning period, weaned pigs consumed (24.3 +/- 2.8 g/suckling) the same amount (P greater than .1) as non-weaned littermates (28.7 +/- 1.8 g/suckling).(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Relations between body weight, feed intake, daily weight gain, and exocrine pancreatic secretion in chronically catheterized growing pigs

The aim of this investigation was to develop models that would make it possible to correct exocrine pancreatic secretion data for the effect of BW and feed intake in growing pigs. In addition, the significance of exocrine pancreatic secretion for daily weight gain (DWG) was studied. Data were used from 10 pigs (16 to 32 kg BW) surgically fitted with chronic pancreatic catheters. The samples were collected under controlled conditions for two to five experimental days per animal (a total of 39 observations), during 2 h preprandially and during 2 h when feeding (postprandially). The exocrine pancreatic secretion traits included the hourly output of volume, the amount of protein, and trypsin and amylase activities. Multiple linear regressions were used to develop models to describe exocrine pancreatic secretion. The individual pig was the most important source of variation in the model. With increasing BW, 7 out of 10 pigs showed an increase in exocrine pancreatic secretion. However, the slopes of the regression lines differed between animals, which made it impossible to develop general models for the correction of secretion data for the effect of BW. Postprandial exocrine pancreatic secretion was always higher than preprandial secretion, but the amount of feed intake per se did not seem to affect secretion. Exocrine pancreatic secretion and DWG were positively correlated. We concluded that, under the present circumstances, expressing secretion per kilogram BW or kilogram feed intake was not feasible. Expressing secretion per hour was the best way to present the data.     

Effect of decreased feed intake on serum and pancreatic alpha-amylase of broiler chickens

Removal of feed from 20-day-old broiler chicks for 24 hours caused serum and pancreatic alpha-amylase activities to increase almost twofold. A 24-hour feeding period following feed removal caused a reduction in serum alpha-amylase to basal levels and a sixfold reduction in pancreatic alpha-amylase activity. Serum alpha-amylase levels remained elevated after long-term feed restriction in adult broilers compared with levels in full-fed controls. Reduction in feed intake in chicks caused by coccidial infections also resulted in increased serum alpha-amylase. In all cases, the degree of change in serum alpha-amylase corresponded inversely to feed intake. It is proposed that the pancreas synthesizes a specific quantity of alpha-amylase, which does not change even under conditions of extended underconsumption of feed. The rate of alpha-amylase secretion is determined, at least indirectly, by the rate of carbohydrate metabolism, and the remainder of the enzyme is stored in the pancreatic cells. A small percentage of the stored enzyme diffuses into the blood and thus directly reflects increased secretion or accumulation of alpha-amylase in the pancreas in response to conditions of carbohydrate utilization.     

外源核苷酸对断奶仔猪生产性能和小肠发育的影响

选用21日龄断奶仔猪160头,随机分为5组,每组4个重复。对照组饲喂基础日粮,试验组饲喂含0.2%核苷酸的日粮。经21d试验,结果表明:日粮中添加0.2%核苷酸能显著提高断奶仔猪的饲料利用率,饲料转化率比对照组提高16.90%(P<0.05),并能显著提高仔猪断奶后第7天十二指肠绒毛高度和第14天回肠黏膜DNA含量,分别比对照组提高44.79%(P<0.05)和111.65%(P<0.05)。     

Effects of diet complexity and dietary lactose levels during three starter phases on postweaning pig performance

Four experiments involving 1,005 crossbred pigs weaned at 19 +/- 2 d of age evaluated the effect of diet complexity and lactose level on starter pig performances. Experiment 1 was a randomized complete block (RCB) conducted in nine replicates with 135 pigs. A complex diet using several protein sources, a semicomplex diet with fewer protein sources, and a simple diet of corn and soybean meal comprised the three treatment groups. All diets contained 25% lactose (as-fed basis) with lysine (total) constant from d 0 to 14 (1.55%) and d 14 to 28 (1.45%), respectively. Gain, feed intake, and feed efficiency (P < 0.05) improved as diet complexity increased during both periods. In Exp. 2, 240 pigs in eight replicates in a RCB design were fed complex diets, but dietary lactose (total; as-fed basis) levels ranged from 10 to 35% in 5% increments from 0 to 14 d after weaning. From 14 to 30 d, a common 17% lactose diet was fed to evaluate the effects of early lactose level on subsequent responses. Gains (P < 0.05) increased for the 0- to 7- and 0- to 14-d periods as lactose increased to 30%. Similar gains resulted for all treatment groups from 14 to 30 d after weaning, with no evidence of compensatory responses to early lactose levels. In Exp. 3, 330 pigs were fed complex diets. From 0 to 7 d after weaning, the diets contained 25% lactose (as-fed basis), and from 7 to 21 d postweaning, the lactose levels ranged from 7 to 31% in 5% increments. Gain (P < 0.01) and feed efficiency (P < 0.05) increased from 7 to 21 d to the 17% lactose level. In Exp. 4, 300 pigs were fed 25 and 17% (as-fed basis) lactose diets from 0 to 7 and 7 to 21 d postweaning, respectively. From 21 to 35 d postweaning, lactose levels of 0 to 20% in 5% increments were added to a corn-soybean meal diet. The experiment was conducted as a RCB design in 12 replicates. Gain (P < 0.05) and feed intake (P < 0.05) increased to 10 to 15% lactose. When the data from Exp. 4 were partitioned into lighter (15.0 kg) and heavier (17.7 kg) pig weight replicates, only the lighter replicates had significant improvements in gain, feed intake, and feed efficiency (P < 0.05) in response to dietary lactose. These results demonstrated that starter pigs performed better when fed complex diets, that dietary lactose levels of 25 to 30% (to 7 kg BW) during the initial week postweaning, 15 to 20% lactose during d 7 to 21 (to 12.5 kg BW), and 10 to 15% lactose during d 21 to 35 postweaning (to 25 kg BW) resulted in maximum performance.