The effects of citric acid on phytate-phosphorus utilization in young chicks and pigs

Several bioassays were conducted with young chicks and pigs fed phosphorus (P)-deficient corn-soybean meal diets. With diets for chicks containing .62% Ca and .42% P (.10% available P), graded doses of a citric acid + sodium citrate (1:1, wt:wt) mixture (0, 1, 2, 4, or 6% of diet) resulted in linear (P < .01) increases in both weight gain and tibia ash. Relative to chicks fed no citric acid, tibia ash (%) and weight gain (g/d) were increased by 43 and 22%, respectively, in chicks fed 6% citric acid. Additional chick trials showed that 6% citric acid alone or sodium citrate alone was as efficacious as the citric acid + sodium citrate mixture and that 1,450 U/kg of phytase produced a positive response in bone ash and weight gain in chicks fed a diet containing 6% citrate. Varying the Ca:available P ratio with and without citrate supplementation indicated that citric acid primarily affected phytate-P utilization, not Ca, in chicks. Moreover, chicks did not respond to citrate supplementation when fed a P-deficient (.13% available P), phytate-free casein-dextrose diet. Young pigs averaging 10 to 11 kg also were used to evaluate citric acid efficacy in two experiments. A P-deficient corn-soybean meal basal diet was used to construct five treatment diets that contained 1) no additive, 2) 3% citric acid, 3) 6% citric acid, 4) 1,450 U/kg phytase, and 5) 6% citric acid + 1,450 U/kg phytase. Phytase supplementation increased (P < .01) weight gain, gain:feed, and metatarsal ash, whereas citric acid addition increased only gain:feed (P < .05) and metatarsal ash (P < .08). A subsequent 22-d pig experiment was conducted to evaluate the effect of lower levels of citric acid (0, 1, 2, or 3%) or 1,450 U/kg phytase addition to a P-deficient corn-soybean meal diet. Phytase supplementation improved (P < .01) all criteria measured. Weight gain and gain:feed data suggested a response to citric acid addition, but this was not supported by fibula ash results (P > .10). The positive responses to phytase were much greater than those to citric acid in both pig experiments. Thus, dietary citric acid effectively improved phytate P utilization in chicks but had a much smaller effect in pigs.     

Effects of calcium soaps of long-chain fatty acids on feedlot performance, carcass characteristics and ruminal metabolism of steers

Two trials were conducted to determine the effects of calcium soaps of long-chain fatty acids (calcium soap) on feedlot performance, diet digestibility, carcass characteristics and ruminal metabolism of steers fed diets (85% concentrate:15% corn silage) containing 0, 2, 4 or 6% calcium soap. In Trial 1, increasing calcium soap decreased (P less than .05) DM, CP and gross energy intake but increased total fatty acid intake. Feed to gain ratio tended to improve with increased calcium soap; gross energy conversion was not affected (P greater than .05) by diet. Average daily gain and hot carcass weight decreased (P less than .05) with addition of calcium soap; other carcass characteristics were not affected (P greater than .05). Apparent digestibilities of DM, N, energy and ash were not affected (P greater than .05) by calcium soap. Neutral detergent fiber digestibility increased linearly (P less than .08) with increasing calcium soap, whereas digestibility of total fatty acids was affected quadratically (P less than .05); fatty acid digestibility was similar among 0, 2 and 4% calcium soap diets but decreased for the 6% calcium soap diet. In Trial 2, increased calcium soap did not affect (P greater than .05) ruminal VFA concentrations, pH or in sacco NDF disappearance of orchardgrass following 12, 24 and 48 h of incubation. Calcium soap increased (P less than .07) ruminal concentrations of calcium soap fatty acids at 1, 2, 4 and 8 h postfeeding. Calcium soap did not improve performance of feedlot cattle fed high-concentrate diets. Further, calcium soap did not affect ruminal fermentation and did not dissociate significantly even when ruminal pH was below 6 for extended periods of time.     

Dietary conjugated linoleic acids alleviate early inflammatory response caused by lipopolysaccharide injection in male broiler chicks

An experiment was undertaken to determine if dietary conjugated linoleic acid (CLA) influences the early stage of the inflammatory response caused by a single injection of Salmonella enteritidisi lipopolysaccharide (LPS) in male broiler chicks. Chicks (7 days old) were fed either 0 or 10 g CLA/kg in their diet for 21 days. At 28 days old, birds were injected intraperitoneally with 1.5 mg LPS/kg body weight after 12 h fasting. Changes in feed intake, rectal temperature and plasma α‐1 acid glycoprotein and ceruloplasmin concentrations were measured during 24 h after LPS injection. Chicks fed the CLA diet were fed more feed for 24 h, had a lower rectal temperature at 9 and 24 h and a lower plasma α‐1 acid glycoprotein concentration at 24 h after LPS injection than chicks fed the basal diet. Plasma ceruloplasmin concentration tended to be lower in chicks fed the CLA diet than in chicks fed the basal diet. The results suggest that dietary CLA alleviate undesirable early inflammatory response due to LPS injection in male broiler chicks.     

Effect of sex and reproductive status on sucrose preference, food intake, and body weight of dogs

In a study of preferences for diets containing 1% to 20% sucrose over a bland diet, both female and male dogs preferred the diets containing sucrose over a bland diet, but female dogs had a significantly (P less than 0.05) greater preference for 1% sucrose than did males. Differences between sexes were not observed at the higher concentrations. Mean daily caloric intake was calculated for 12 bitches fed ad libitum during metestrus, estrus, and anestrus, as determined from metachrome-stained vaginal smears. Mean daily caloric intake was lowest during estrus (149 +/- 17 kcal/kg of body weight), was higher during metestrus (159 +/- 8 kcal/kg of body weight), and was highest (175 +/- 9 kcal/kg of body weight) during anestrus. Ovariohysterectomized bitches gained significantly (P less than 0.01) more weight (1.3 +/- 0.3 kg) in the first 10 days after surgery than did sham operated controls (0.3 +/- 0.1 kg). Food intake also was significantly greater ( less than 0.01) in the ovariohysterectomized bitches (1,708 kcal/day) than in the sham operated controls (1,423 kcal/day). Depth of subcutaneous fat in shoulder, rib, and rump areas of ovariohysterectomized bitches was not significantly different from that of intact bitches.     

Effects of Source of Inorganic Phosphorus and Phytase Supplementation on Performance, Physiological Parameters and Bone Mineralization in Broilers

The objective of this study was to eval- uate the effects of inorganic phosphorus source and phytase addition on performance, nutrient digestibility and bone mineralization in broiler chickens. In Exp. 1,150 two-day old, male broiler chicks were fed a corn-soybean meal basal diet supplemented with phos- phorus provided by dicalcium phosphate, tricalcium phosphate or defluorinated rock phosphate. Five cages containing 10 birds were allotted to each of the three treatments. In Exp. 2,120 three-day old, male broiler chicks were fed the basal diet from Exp. 1 supplemen- ted with 0,250,500 ,or 1,000 P-＇rU phytase per kg of diet. Six cages containing five chicks were allotted to each of the four treatments. In Exp. 1, there was no difference in weight gain, feed intake or feed conver- sion as a result of feeding the different sources of in- organic phosphorus. The digestibility of phosphorus was significantly lower （P =0.01 ） for chicks fed di- ets supplemented with tricalcium phosphate than for chicks fed the other two diets. However, despite the lower digestibility, serum phosphorus levels did not differ among the three treatments. For Exp. 2, feedconversion showed a linear improvement （P = 0.03 ） with increasing levels of phytase inclusion （ days 0 to 33 ）. Phytase supplementation resulted in linear increa- ses in the digestibility of dry matter （P = 0.02 ）, crude protein （ P --- 0.04 ） and energy （ P 〈 0.01 ）. Chicks fed 1,000 FTU/kg phytase had significantly higher bone calcium （ P = 0.05 ） and bone breaking strength （P = 0.04 ） than chicks fed the basal diet on day 33. In conclusion, the results of the current study indicated that the performance of birds fed diets sup- plemented with dicalcium phosphate, tricalcium phos- phate or defluorinated phosphate was similar and therefore production costs could be lowered by choo- sing the cheapest inorganic phosphorus source when formulating diets for poultry. When diets were formu- lated to meet dietary phosphorus requirements, the growth of broilers was not enhanced with phytase sup- plementation. However, increases in feed conversion and bone breaking strength and its potential to impact culling and mortality in broiler operations may be suf- ficient justification for the routine inclusion of phytase in diets fed to broilers.     

Effects of Source of Inorganic Phosphorus and Phytase Supplementation on Performance, Physiological Parameters and Bone Mineralization in Broilers

The objective of this study was to evaluate the effects of inorganic phosphorus source and phytase addition on performance, nutrient digestibility and bone mineralization in broiler chickens. In Exp. 1, 150 two-day old, male broiler chicks were fed a corn-soybean meal basal diet supplemented with phosphorus provided by dicalcium phosphate, tricalcium phosphate or defluorinated rock phosphate. Five cages containing 10 birds were allotted to each of the three treatments. In Exp. 2, 120 three-day old, male broiler chicks were fed the basal diet from Exp. 1 supplemented with 0, 250, 500, or 1,000 FTU phytase per kg of diet. Six cages containing five chicks were allotted to each of the four treatments. In Exp. 1, there was no difference in weight gain, feed intake or feed conversion as a result of feeding the different sources of inorganic phosphorus. The digestibility of phosphorus was significantly lower (P = 0.01) for chicks fed diets supplemented with tricalcium phosphate than for chicks fed the other two diets.  However, despite the lower digestibility, serum phosphorus levels did not differ among the three treatments. For Exp. 2, feed conversion showed a linear improvement (P = 0.03) with increasing levels of phytase inclusion (days 0 to 33).  Phytase supplementation resulted in linear increases in the digestibility of dry matter (P = 0.02), crude protein (P = 0.04) and energy (P < 0.01).  Chicks fed 1,000 FTU/kg phytase had significantly higher bone calcium (P = 0.05) and bone breaking strength (P = 0.04) than chicks fed the basal diet on day 33. In conclusion, the results of the current study indicated that the performance of birds fed diets supplemented with dicalcium phosphate, tricalcium phosphate or defluorinated phosphate was similar and therefore production costs could be lowered by choosing the cheapest inorganic phosphorus source when formulating diets for poultry. When diets were formulated to meet dietary phosphorus requirements, the growth of broilers was not enhanced with phytase supplementation.  However, increases in feed conversion and bone breaking strength and its potential to impact culling and mortality in broiler operations may be sufficient justification for the routine inclusion of phytase in diets fed to broilers.     

Effect of ochratoxin A on Escherichia coli-challenged broiler chicks

A study was conducted to evaluate the effects of ochratoxin A (OA) on Escherichia coli-challenged broiler chickens. Day-old broiler chicks were separated into two groups of 92 chicks each, with one group fed a control mash diet, and the other fed a mash diet containing 2 ppm OA. On day 14, each group was further separated into two groups, with one group inoculated with E. coli O78 (1 x 10(7) colony-forming units/0.5 ml), whereas the other group was not inoculated with E. coli. After E. coli inoculation on day 14, four birds from each group were euthanatized at 1, 2, 3, 5, 7, 10, 14, and 21 days postinoculation. Escherichia coli infection caused dullness, depression, huddling, and diarrhea. Mortality was 14.3% in chicks infected with E. coli but fed no OA. Mortality increased to 35.7% in chicks fed OA and infected with E. coli. Decreased body weight and reduced feed intake were observed in chicks fed OA, and the effects were more pronounced in chicks fed OA and infected with E. coli. Increased serum levels of aspartate aminotransferase, alanine aminotransferase, uric acid, and creatinine and decreased levels of total proteins, albumin, globulins, calcium, and phosphorus were observed in OA-fed birds. Escherichia coli infection did not cause significant alteration in any of the serum biochemical parameters. The presence of OA in poultry rations increased mortality and the severity of an E. coli infection.     

Effects of Pediococcus- and Saccharomyces-based probiotic (MitoMax) on coccidiosis in broiler chickens

Coccidiosis is the major parasitic disease of poultry. In this study, the role of the commercial probiotic MitoMax which contains Pediococcus acidilactici and Saccharomyces boulardii was evaluated by measuring body weight gain, fecal oocyst shedding, and serum antibody responses as an alternative control method of prophylactic drug against coccidiosis. Day-old broiler chicks were fed regular or probiotic diets supplemented with MitoMax at 0.01%, 0.1%, or 1.0% of diet, and challenged 2 weeks later with 5000 oocysts of either Eimeria acervulina (EA) or Eimeria tenella (ET). Birds fed 1.0% or 0.1% MitoMax-supplemented diets in EA- or ET-infected groups shed less (P<0.05) oocysts than control-infected chickens. Also, chickens fed 0.1% MitoMax-supplemented diet and infected with EA exhibited higher (P<0.001) serum Eimeria-specific antibodies than other groups. These results demonstrate that MitoMax may enhance the resistance of birds against coccidiosis by enhancing humoral immunity when included at > or = 0.1% of the broiler diet.     

Effects of Dietary Zinc and Calcium on Select Immune Functions of Channel Catfish

Abstract

The effects of dietary zinc and calcium on immunocompetence of channel catfish Ictalurus punctatus (mean initial weight = 3.1 g/fish) were determined after a 10-week feeding trial. Fish were fed daily amounts equal to 3% of their body weight of one of six purified diets that were deficient in zinc (2 mg/kg of diet), calcium (0.02% of diet), or both; replete with zinc (20 mg/kg of diet) and calcium (0.5% of diet); or excessive in zinc (200 mg/kg of diet) or calcium (2.5% of diet). Immunocompetence of immunized and nonimmunized fish fed the various diets was assessed by measuring serum immunoglobulin M levels and mortality after an intraperitoneal injection of live Aeromonas hydrophila. Channel catfish fed diets deficient in zinc, calcium, or both had significantly (P ≤ 0.05) less weight gain and survival as compared with those fed diets replete with or excessive in zinc or calcium. Tissue mineral concentrations of fish indicated that various levels of zinc and calcium nutriture existed when immune functions were tested. Diet affected mortality of only nonimmunized fish in the bacterial-challenge test; zinc deficiency and calcium excess decreased mortality. Whereas growth and survival of fish were reduced by dietary zinc or calcium deficiency, the measured immunological characteristics were not equally impaired by these mineral deficiencies.     

Immune Competence,Resistance to Escherichia coli and Growth in Male Broiler Parent Chicks Fed Different Levels of Crude Protein

Immune competence, resistance to Escherichia coli and growth were measured in female chicks of broiler male parent lines from four different commercial sources. These chicks were fed with three levels of dietary crude protein (CP) from day-old. The protein contents in the diets were 18%, 20.5% and 23%; these diets are referred to as the low-, medium- and high-protein diets, respectively. There was a significant genotype by dietary protein interaction for body weight at 35 days of age but not at 14 or 28 days of age. At 14 days of age, the chicks fed on the high-protein diet weighed significantly more than those fed on the low-protein diet, but there were no differences between the chicks fed on the medium- and low-protein diets. The influence of CP content on body weight had disappeared by 28 days of age. There were significant differences between the genotypes in antibody production in response to sheep red blood cell (SRBC) inoculation, but no such differences were observed between the chicks fed the different levels of dietary protein. Chicks fed on the high-protein diet had lower lesion scores following E. coli inoculation than those fed on the low-protein diet. There were also significant differences in lesion scores among the genotypes. Genotypes with heavier body weights had significantly higher lesion scores and lower antibody titres than those with less body weight. Also, genotypes of lower body weight had a greater cutaneous basophilic hypersensitivity response to phytohaemaglutinin-P inoculation, and a better humoral response against SRBC and a lower heterophil to lymphocyte ratio.     

Bioavailability of threonine in soybean meal for rats and chicks.

The bioavailability of threonine in soybean meal and the effects of the excess amino acids in soybean meal on the estimate were measured using rats and chicks in slope-ratio assays. In Exp. 1, a corn-based diet containing .23% threonine was supplemented with 0 to 45% L-threonine in .05% increments. The growth rate of weanling rats fed these diets increased quadratically (P less than .001) with L-threonine addition, the increase being essentially linear up to the .10% addition. In Exp. 2, the basal diet was supplemented with 0, .025, .050, .075, or 100% threonine from L-threonine, simulated soybean meal (a mixture of crystalline amino acids with a pattern designed to simulate soybean meal), or soybean meal. Regressions of partitioned weight gain and body N gain of rats vs supplemental threonine intake were calculated for each source using multiple regression. Slope ratios (soybean meal:L-threonine) were .91 for weight gain and .92 for body N gain. The additional amino acids in simulated soybean meal did not affect the estimate. For Exp. 3, a corn-soybean meal-based diet containing .48% threonine was supplemented with 0 to 60% L-threonine in .10% increments. The growth rate of broiler chicks fed the diets increased quadratically (P less than .001) with L-threonine addition. The increase was essentially linear up to the .10% addition. In Exp. 4, the basal diet was supplemented as in Exp. 2. Regressions of partitioned weight gain of chicks vs supplemental threonine intake were calculated for each source. The slope ratio for soybean meal:L-threonine was 1.03; however, the model exhibited fundamental invalidity and therefore the estimate should be interpreted with caution. The additional amino acids in the simulated soybean meal did not affect the value.     

Effect of early stages of fungal development on the nutritional value of diets for broiler chicks

During 65 d of storage a gradual increase in fungal activity (evaluated by CO2 production) was observed in a diet with its moisture content elevated to 136 g/kg. This activity was inhibited by supplementation of the wetted diets with either calcium propionate (3 g/kg) or Agrosil (2 g/kg). The fat content of the wetted untreated diet decreased between the 18th and the 45th d of storage from 38 to 29 g/kg. This change was prevented by the addition of either of the two fungistats. The weight gains of 7-d-old female broiler chicks fed on the wetted diets with or without the fungistats from the 18th d after their preparation for 27 d, did not differ significantly (P greater than 0.05) from those of birds fed on the unwetted diet. However, the food:gain ratio of chicks fed on the unwetted diet was significantly (P less than 0.05) better than that of chicks fed on the fungistat-free wetted diet. The results from birds fed on the fungistat-supplemented wetted diets were intermediate. It is concluded that the early stages of fungal activity (characterised by increased CO2 production, without changes or with only a slight decrease in fat content) have only a minor effect on the nutritional value of diets.     

Effects of supplemental ascorbic acid on performance, organ weight and plasma cholesterol concentration in broilers treated with propylthiouracil

1. Four experiments were conducted to determine if dietary ascorbic acid (AA) affects body weight gain, food intake, organ weights, plasma cholesterol concentration, and ascorbic acid concentration in the plasma and liver of growing male broilers treated with an antithyroidal agent, propylthiouracil (PTU). 2. In the first experiment, 15 mg AA was administered daily into the crop of chicks fed on a diet supplemented with or without PTU (500 mg/kg). Administration of AA reduced plasma cholesterol concentrations in the PTU-treated chicks. 3. In the other three experiments, chicks were given the basal diet or an AA-containing (3 g/kg) diet supplemented with or without PTU (250 mg or 500 mg/kg). Feeding AA partly prevented the decreases in body weight gain, gain:food ratio and weights of the bursa of Fabricius and thymus in chicks fed on the 250 mg/kg PTU diet, and also prevented the increase in plasma cholesterol concentrations in chicks fed on the PTU diet. 4. These results suggest that AA improves the performance of chicks with experimentally induced hypothyroidism.     

Effect of ochratoxin A on broiler chicks challenged with Salmonella gallinarum

1. A study was conducted to evaluate the effects of ochratoxin A (OA) on broiler chicks challenged with Salmonella gallinarum. 2. One hundred and seventy-six 1-d-old broiler chicks were divided into two groups of 88 chicks each, with one group fed on a control mash diet and the other given a mash diet containing 2 ppm OA. On d 14, each group was further subdivided into two groups with one group infected with S. gallinarum and the other uninfected. 3. Following S. gallinarum inoculation on d 14, 4 birds from each group were killed at 1, 2, 3, 5, 7, 10, 14 and 21 d post inoculation. 4. S. gallinarum infection caused dullness, depression, weakness, increased thirst, droopy wings, ruffled feathers and greenish-yellow diarrhoea. S. gallinarum infection in the absence of OA caused 11.5% mortality which increased to 28.8% in the presence of OA. 5. Decreased body weight and reduced feed intake were observed in chicks fed on the diet containing OA. S. gallinarum infection also reduced the body weights of chicks, with the effects being more marked in chicks receiving OA. The OA diet led to increased serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, uric acid and creatinine, and decreased levels of total proteins, albumin, globulins, calcium and phosphorus. S. gallinarum infection did not cause significant alteration in any of the serum biochemical parameters. 6. Mortality and the severity of S. gallinarum infection in broiler chicks were increased by the presence of OA in the diet.     

Influence of pre-fast dietary roughage content on recovery from feed and water deprivation in beef steers

Sixty steer calves of mixed British breeding averaging 268 kg were randomly assigned to four treatment groups of 15 calves each to determine the influence of pre-fast dietary roughage content on recovery from feed and water deprivation. Three groups were fed diets containing either 84 (HR), 60 (MR) or 35% (LR) roughage at 1.75% of body weight for 3 d. Calves in these three groups were deprived of feed and water for 24 h, limit-refed and watered for 24 h, and deprived of feed and water for 48 h (deprivation). Calves were then fed the MR diet ad libitum for 2 wk. The fourth group of control steers was continuously fed the MR diet throughout the experiment. Realimentation weight gains and feed intakes were not affected by pre-fast diet roughage content. Blood packed cell volume increased (P less than .05) during deprivation. Blood potassium was not affected by deprivation but declined (P less than .05) upon refeeding. Plasma urea-N increased (P less than .05) during deprivation but returned to pre-fast concentrations by d 3 of realimentation. Ruminal volume was not significantly affected by deprivation but increased (P less than .05) by 50 to 100% upon refeeding. Ruminal fluid total volatile fatty acid (VFA) concentrations declined (P less than .05) during deprivation. On d 3 of realimentation, a linear contrast (P less than .05) was observed between total VFA concentrations and the pre-fast diet roughage content.(ABSTRACT TRUNCATED AT 250 WORDS)     

蛋鸡磷缺乏症治疗措施的研究

试验一,选择75羽1日龄健康的罗曼商品蛋鸡,随机分成2个组,第一组20羽,第二组55羽,每个组设2个重复,分别饲喂含有0.4%和0.11%有效磷的日粮.试验至30d,低磷组受试鸡胸骨弯曲发生率达52%,增重显著降低(P＜0.05),确认为雏鸡患有磷缺乏症.试验二,选48羽患磷缺乏症的商品蛋鸡,随机分成4个组,分别饲喂含0.11%有效磷、0.4%有效磷、0.4%有效磷+500IU/kg维生素D3、0.6%有效磷的日粮.试验20d,结果显示:第一组增重、耗料量显著低于第二、三、四组(P＜0.05);第一组胸骨弯曲、胸部囊肿发生率显著高于第二、三、四组(P＜0.05);第一组血浆、全血、胫骨钙、磷显著低于第二、三、四组(P＜0.05).3个治疗组之间没有明显的差别,表明当雏鸡患有磷缺乏症时,日粮中添加有效磷至0.4%,即可获得良好的疗效.     

Relationship between food consumption and energy and nitrogen utilisation by chicks given varying amounts of standard and leucine-, isoleucine- and valine-deficient diets

The effect of different amounts of food, varying from below to above the rate of voluntary intake, was studied in chicks using a standard diet and diets containing only half the recommendation concentrations of leucine, isoleucine or valine. Irrespective of diet the body weight gain of the chicks increased with increasing food consumption. The body weight gain of chicks given the leucine-deficient diet was similar to that of chicks given the same amount of the standard diet. In contrast, the body weight gains of chicks given either the valine- or isoleucine-deficient diet were significantly less than that of chicks given the same amount of the standard diet. When the food intakes of the birds were similar the differences in body protein and water contents of the birds fed the different diets reflected differences in body weight gains, whereas body fat content was affected in the reverse manner. Retention and retention rate of dietary energy increased as food consumption increased. This was particularly evident in chicks given the isoleucine-deficient diet, followed by those given the valine-, leucine-deficient and standard diets. For all diets, the amounts of nitrogen retained and nitrogen retention rate (N retained/N consumed) increased in line with body weight gain. The metabolisable energy values of the diets were similar, except for the isoleucine-deficient diet which had a significantly higher metabolisable energy value than the standard valine-deficient diets.     

Tryptophan and threonine requirements of young pigs and their effects on serum calcium, phosphorus and zinc concentrations

Four 28-d trials were conducted using a total of 432 pigs, with average initial weight across trials ranging from 6.3 to 9.7 kg, to estimate the tryptophan (trials 1 and 2) and threonine (trials 3 and 4) requirements of pigs fed low protein, corn-sunflower meal diets. The effect of tryptophan, threonine and protein level on serum calcium, phosphorus and zinc also was studied. The diets contained either 12 or 13% protein and were calculated to be adequate in all nutrients except crude protein and the amino acid being investigated. A lysine supplemented, 18% protein, corn-sunflower meal diet was included in all trials as a positive control. In trial 1, weight gains of pigs increased linearly (P less than .005) while feed conversion improved cubically (P less than .05) as dietary tryptophan increased from .14 to .22%. Pigs fed the 18% protein diet gained faster (P less than .05) and required less feed/gain than pigs fed low protein diets. In trial 2, weight gains improved quadratically (P less than .005) and feed conversion improved linearly (P less than .05) as dietary tryptophan increased from .104 to .204%. Serum phosphorus and zinc concentrations were lower (P less than .05) in pigs fed the 18% protein diet. In both trials, serum urea N responded quadratically (P less than .05) to increasing dietary tryptophan, and was lower (P less than .05) in pigs that were fed diets supplemented with L-tryptophan than in those fed the low protein basal or 18% protein diets.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of betaine and salinomycin on intestinal absorption of methionine and glucose and on the ultrastructure of intestinal cells and parasite developmental stages in chicks infected with Eimeria acervulina

The effect of betaine and salinomycin on absorption of methionine and glucose in tissue from the duodenal loops of Eimeria acervulina-infected chicks was determined. Differences in the ultrastructure of the intestinal cells and parasite developmental stages were also examined. With a drug-resistant isolate of E. acervulina, methionine absorption was significantly higher in chicks fed a basal diet supplemented with 0.15% betaine as compared with absorption in chicks fed the unsupplemented basal diet. Addition of 66 ppm salinomycin to the diet containing betaine did not further enhance absorption. Conversely, with a drug-sensitive isolate, methionine absorption was significantly higher in chicks fed a diet supplemented with both betaine and salinomycin than in chicks fed the unsupplemented basal diet. Tissue from chicks fed any of the supplemented diets was usually significantly heavier than that from chicks fed the unsupplemented diet, even when weight gains of the birds were similar. Glucose absorption was similar in all diet groups. Epithelial cells in coccidia-infected and uninfected chicks fed diets supplemented with betaine or betaine plus salinomycin were less electron dense than cells from chicks fed diets that were not supplemented with betaine. Merozoites of E. acervulina in chicks fed diets supplemented with salinomycin had extensive membrane disruption and vacuolization, but the damage was prevented when betaine was added to the diet. Numerous merozoites and intact schizonts were seen in the intestinal lumen of chicks fed the diet containing betaine plus salinomycin.     

共轭亚油酸对肉仔鸡体组成和肉品品质的影响

本试验旨在探讨日粮添加共轭亚油酸(CLA)对肉仔鸡体组成和肉品品质的影响。240只1日龄肉仔鸡随机分配到4个日粮处理组(0%、0.25%、0.5%和1%CLA),每个处理6个重复,每个重复10只鸡。试验结果表明:42d时,0.5%和1%CLA组肉仔鸡胸肌率显著高于对照组(P<0.05),1%CLA组肉仔鸡42d腿肌率显著高于对照组,肉仔鸡的腹脂率在各处理之间没有显著差异(P>0.05),1%CLA组肉仔鸡胸肌粗蛋白质粗脂肪比显著高于对照组(P<0.05)。0.5%、1%CLA组肉仔鸡胸肌滴水损失和丙二醛(MDA)含量显著降低(P<0.05)。试验结果表明,CLA可改善肉仔鸡屠体性状,增加鸡肉系水力和延长货架存放时间。