Endogenous nitrogen metabolism in 15N-labeled swine. 1. Course of 15N-labeling and 15N excretion in urine and feces under 4 different diets

Four male castrated pigs (55-65 kg) either received a wheat--fish meal diet (1 and 2) or a wheat--horse bean diet (3 and 4) without straw meal supplement (1 and 3) or with a supplement of 20% DM partly hydrolysed straw meal to the DM of the ration (2 and 4). In order to investigate whether a 15N-labelling of the pigs is also possible with a protein excess in the ration, the animals 1 and 2 received 24.8 g and the animals 3 and 4 = 11.6 g crude protein/kg0,75 live weight. During a 10-day 15N-labelling 385 mg 15N-excess (15N') per kg0,75 were applied in a mixture of ammonia acetate and ammonia chloride in the feed. During the period of 15N-labelling the following quotas of the applied 15N-amount were incorporated: 1 = 10.2%, 2 = 7.2%, 3 = 18.7%, 4 = 14.4%. 15N-excretion in both TCA fractions of faeces showed a highly significant positive correlation to the increasing content of crude fibre in the 4 diets. The immediate 15N-incorporation into the TCA-precipitable fraction of faeces (from the 2nd of the beginning of the 15N-application onwards) proves that 15N enters the large intestine endogenously (probably as 15N-urea) and serves bacterial protein synthesis. Three days after the last 15N-application the pigs were killed. The following values of atom-% 15N' could be determined in the TCA-precipitable blood plasma and in the TCA-precipitable fraction of the liver: 1 = 0.18 and 0.19 resp., 2 = 0.22 and 0.27 resp., 3 = 0.22 and 0.23 resp. and 4 = 0.24 and 0.26 resp. The other examined organs and tissues showed smaller differences between the test animals. The following atom-% 15N' were measured in the TCA-precipitable fractions on an average of the 4 test pigs: kidney = 0.20, pancreas = 0.18, intestinal wall tissue, duodenum = 0.18, jejunum (beginning) = 0.17, jejunum (end) = 0.15, ileum = 0.15, caecum = 0.16, colon (beginning) = 0.15, colon (middle) = 0.14, colon (end) = 0.13, stomach (cardia) = 0.11, stomach (fundus) = 0.12, spleen = 0.13, heart = 0.12, skin = 0.07 and skeleton muscles = 0.06. The results show that the 15N-labelling of tissues and organs of pigs is also possible at a high level of protein supply by means of an oral application of 15N ammonia salts.     

The determination of a gross utilization of 15N-lysine in laboratory rats. 1. Experiment with normal intestinal flora (without antibiotic supplement)]

Wistar rats of a live weight of about 100 g were divided into 14 groups (5 animals/group). The rations given supplied the animals with 75%, 100% and 125% lysine, which brought about a moderate growth of the animals of approximately 2 g/animal and day achieved by limited feeding. The 3 lysine levels mentioned could be achieved by lysine supplements (L-lysine-HCl) for the following rations: barley (B), wheat (W), and wheat gluten (WG). For isolated soybean protein (assay protein) (S) the lysine levels 100% and 125% and for soybean meal (SM) the levels 116% and 125% could only be achieved. A control group with whole egg ration (W) (with its natural lysine content of 125% of the requirement) were also tested as comparison. During the 10-day period of the main experiment all 14 rations were supplemented with 0.5 g 15N-lysine (alpha amino group, 95% labelled with 15N). The N balance could only be significantly improved by lysine supplements in the rations B, W and SM with the lysine level of 125%. The biologic value of the protein sources was in rations B and WG also significantly improved by the highest lysine supplement. 15N excess (15N') from the deaminated 15N lysine was excreted with diet B rich in crude fibre mainly in faeces (more than 15% of the intake) and only about 10% in urine. With the diets without native crude fibre the excretion quota changed in favour of urine. The following 15N' amounts in per cent of 15N' intake from lysine were excreted in urine and faeces: B 75 = 31.3, B 100 = 30.9, B 125 = 28.0, W 75 = 24.3, W 100 = 32.2, W 125 = 32.6, GW 75 = 18.3, WG 100 = 24.2, WG 125 = 28.1, S 100 = 39.4, S 125 = 50.4, SM 116 = 34.9, SM 125 = 32.9, W 125 = 19.1. 15N excretion in urine and faeces increased in comparable relations in 6 cases of lysine increase levels only. Gross utilization of lysine can only conditionally be quantified by 15N labelled lysine supplement.     

Determination of a prececal N-absorption from natural feed by 15N-labeled laboratory rats using the isotope dilution method

60 Wistar rats (5 animals/group) received 12 different feedstuffs over a period of 7 days and were simultaneously labelled with 15N (orally by means of 15NH4Cl in the feed). In the subsequent 5 days faeces were collected in order to determine the apparent and true digestibility of crude protein. On the 13th experimental day the animals were killed 3 hours after the intake of half the daily ration and the atom-% 15N excess (15N') was determined in the TCA-soluble and TCA-precipitable fractions of the blood plasma and the digesta of the 2nd and 3rd thirds of the small intestine. Precaecal N-absorption was calculated with the help of the quotient [formula: see text] the blood plasma and the digesta The following values (in %) were registered in comparison to true N-digestibility (in the following in brackets): casein = 95.8 (99.2), whole egg = 92.1 (97.5), fish meal = 85.8 (93.4), dried skimmed milk = 98.4 (96.1), soybean meal = 79.6 (90.6), assay protein = 94.2 (98.9), wheat = 92.9 (90.7), barley = 84.3 (84.8), yeast, grown on molasses = 85.6 (87.2), yeast, grown on whey = 86.1 (88.5), biomass of liquid manure = 43.6 (68.9), activated sludge = 54.4 (64.1). One can conclude that the isotope dilution technique demonstrated here as an evaluation method is very well suited for the characterization of the N-digestibility of a feedstuff in the small intestine.     

Resorption and incorporation of radioactive labeled amino acids during administration of various protein carriers in rats. 1. Resorption of 14C leucine and 3H glycine after intragastric administration]

Male Albino rats (90-100 g) were fed ad libitum (with limited periods of feeding) for 14 days. The diets were adjusted to a crude protein content of 10%. Powdered whole egg, fish meal, yeast and gelatine were used as protein sources. Additionally, one group of rats was fed a protein-free diet. On the 15th day of experiment the rats were fed a test diet at a level of 2 g per 100 g of body weight. 2 hrs after that the rats received 25 muCi of 3H glycine and 5 muCi of 14C-L-Leucine per 100 g of body weight administered by way of intragastric infusion. It was found that a large proportion of the radioactive amino acids were absorbed as early as after 0.5 hr. The highest rate of absorption was observed in animals fed dietary proteins of poor quality or a protein free diet, so that in animals receiving a gelatine diet or a protein-free diet only 68.4% or 56.4% of the administered amount of 14C activity were detected inside the gastro intestinal tract after 0.5 hr. Analogous data for the 3H activity were 52.4% and 25.3%. Maximum absorption occurred after 3-7 hrs. Following this the level of radioactivity in the intestinal contents again increased reaching a peak value after 14-24 hrs; in the case of 14C activity this peak value amounted to 25.4% of the administered dose in animals fed the gelatine diet and 32.8% in the group receiving the protein-free diet. It was established that the major proportion of the resecreted amount of 14C activity was present in leucine. Until 72 hrs after the intake of 14C activity the level of radioactivity was again found to decline, a processes which was induced by processes occurring in the large intestines. Moreover, evidence was obtained in confirmation of previous findings, indicating that the composition of faecal amino acids was constant and unaffected by dietary proteins.     

Effect of inclusion of defatted grape seed meal in the diet on digestion and performance of growing rabbits

The digestion and nutritive value of defatted grape seed meal (DGSM) was investigated. A basal diet was formulated to meet requirements of growing rabbits. Another diet was formulated by substituting 15.2% of the basal diet with DGSM. Two hundred eight weaned 30-d-old rabbits were fed these diets, and fattening performance was recorded. Eighty animals were used to study the effect of DGSM inclusion on cecal fermentation traits and intestinal disaccharidase activity at two ages (5 and 35 d after weaning). Fecal apparent digestibility of nutrients was measured in 18 rabbits. A third diet was formulated to contain DGSM (61.3%) as the sole source of fiber and a supplement consisting of wheat flour, casein, lard, and a mixture of vitamins and minerals to avoid nutrient imbalances. This semipurified diet was used to determine cecal digestion traits, disaccharidase activity in the small intestine, fecal apparent digestibility of nutrients, and rate of passage in 70-d-old rabbits. Digestible energy and NDF and CP digestibilities of DGSM calculated by difference were 5.51 +/- 0.89 MJ/kg DM, 24.5 +/- 5.76%, and 46.8 +/- 14.9%, respectively. Inclusion of 15% of DGSM in the basal diet increased ADFI in finishing rabbits (from 9 to 15%; P < 0.05), so that DE intake increased although dietary DE concentration decreased. As a consequence, ADG increased by 3.3% in the whole fattening period (P = 0.046). The increase in ADFI was parallel to an 8% decrease in the weight of cecal contents (P = 0.059), and it was in agreement with the relatively short cecal mean retention time of DGSM (7.61 h) in the semipurified diet. Inclusion of 15% of DGSM in the basal diet did not affect (P > or = 0.20) mortality (10.1%) or cecal concentrations of VFA, NH3 N, or cecal pH either at 5 d (71.9 mM, 17.7 mM, and 5.75, respectively) or at 35 d after weaning (74.6 mM, 10.1 mM, and 5.66, respectively) but improved the sucrase activity in the ileum by 36% (P = 0.031). Digestibility of NDF of DGSM in the semipurified diet was 8.57%, which agrees with the low acidity and weight of cecal contents of animals fed this diet (6.26 and 3.63% BW, respectively). From these results, we conclude that DGSM has a relatively high DE concentration and its inclusion at moderate levels (15%) in the diet exerts a positive effect on ADFI, DE intake, and ADG with no impairment of cecal fermentation and mortality.     

Nitrogen metabolism in the large intestine of ruminants. 1. Metabolism of i.v. infused 15N-urea without additional carbohydrate supply to the large intestine

The experiments were carried out on 3 bulls (body weight: 172, 229 and 193 kg), equipped with ileo-caecal cannulas and with catheters in the jugular veins on both sides. The offered pelleted ration consisted of straw 73%, molasses 12%, cereals 10%, ammonium hydrogen carbonate 3% and urea 2%. Feed intake amounted to about 3 kg per animal and day. During a preliminary period of 5 days 50% of ileal digesta were collected for 12 hours daily, deep-freezed and stored. In the main experiment 15N-urea was infused intravenously for 24 hours. During this period and during the following 6 hours ileal digesta were collected and replaced by precollected, unlabelled digesta. The urea metabolism was estimated by the 15N-labelling of blood urea, by the 15N-excretion via faeces and urea, by the appearance of 15N in ileal digesta and by the 15N-labelling of faecal NAN, NH3 and bacterial fraction. The time course of the 15N-labelling of plasma urea during infusion can be described by an exponential function. The urea flux rate was estimated from the calculated plateau value. The flux rate for the 3 animals was 28.8, 30.7 and 34.8 mumol per minute per kg0.75, respectively. During the infusion of 15N-urea 1.0-2.4% of the infused amount of 15N' appeared in ileal digesta, half of it in the TCA precipitable fraction. At the same time the 15N-labelling of faecal NH3 increased sharply, however, the 15N-labelling of the faecal bacterial fraction was smaller by one order of magnitude. Deficiency of fermentable substrates and problems of inhomogenity of the NH3 pool are supposed as reasons for this result. 30 to 50% of the urea flux entered the digestive tract, the direct entry of urea into the large intestine seems to be only very low.     

小麦全株青贮饲料饲喂育肥猪效果研究

为探讨小麦全株青贮饲料的饲喂方法,以汶鑫黑猪和三元(杜×长×大)杂交猪为研究对象,通过饲养对比试验,证明小麦全株青贮饲料在中国地方猪和进口三元猪上应用的可行性.选择体重相近的汶鑫黑猪120头,分别饲喂基础日粮和用14％的小麦全株青贮饲料替代基础日粮,测定平均日采食量和平均日增重;同时,选取体重相近(60±0.16 kg...     

Isobutylidene diurea, a new NPN source for ruminants. 3. Excretion of isobutylidene diurea following feeding of N-15 isobutylidene diurea to lactating cows

2 experimental cows received isobutylidenedi urea added to a natural diet in amounts of 175 g (I) and 730 g (II) per day for a period of several weeks before the trial was started. On the 1st day of experiment the morning dose was labelled with 5.05 g of excess 15N. 8 hrs after the beginning of the trial of 15N level in the TCE soluble portion of blood plasma (TCE=trichloroacetic acid) increased and remained at an elevated level until the 36th hour of experiment. Similarly, the values for maximum urinary 15N concentrations were maintained for a prolonged period of time. Isobutylidenedi urea was excreted with the urine in rates related to its solubility. Only small percentages of the 15N intake were excreted in the TCE soluble portion of the milk (cow I: 0.03%; cow II: 0.05%). The 15N-labelling of milk protein provides evidence for the fact that nitrogen from IBDU is utilized for the synthesis of milk in the cows. The amount of urea in milk averaged 400 mg per litre. None of the milk samples tested contained IBDU.     

Duodenal bacterial and nonbacterial protein supply in steers fed forage and grain diets

Four beef steers (avg wt 300 kg) fitted with duodenal re-entrant cannulae were used to study the effect of dietary concentrate to forage ratio on bacterial and nonbacterial N flow in the duodenum. According to a change-over design, the steers were designated to receive an all forage (83% alfalfa hay and 17% wheat straw) and an 80% sorghum grain diet. Lignin (ADL) and chromium oxide (Cr2O3) ratio techniques were compared with automated total collection (ATC) of digesta for quantitating duodenal protein flow and efficiency of bacterial N yield in the rumen. Estimates of bacterial protein synthesis and ruminal escape of feed protein based on Cr2O3 and lignin tended to be higher by 8 to 16% than those obtained by ATC. Efficiency of ruminal bacterial protein yield estimated by these two markers tended to be greater than that based on ATC (16 vs 12 g of bacterial protein/100 g ruminal true digestion of dry matter corrected for bacterial cell synthesis). Efficiency values did not differ between diets. Crude protein flow into the duodenum was about 33% greater (P less than .01) for the grain than the forage diet, although protein intake was about 10% less on the grain diet. Duodenal bacterial protein, rather than feed protein escaping ruminal degradation, accounted for most of this difference. Average duodenal flow of N, expressed as g/Mcal metabolizable energy (ME) intake, was 11.9 for the forage diet and 10.3 for the grain diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of dietary defatted diatom biomass on egg production and quality of laying hens

Background

This study was to determine if feeding laying hens with defatted diatom microalgal biomass (DFA) from biofuel production affected their egg production and health status.

Methods

Five replicates of 5 individually caged ISA Babcock White leghorn hens were fed 4 diets, including a corn-soybean meal control diet, a diet containing 7.5% DFA substituting for soybean meal, and diets containing 7.5% or 15% DFA substituting for corn and soybean meal. Body weights, feed intake, feed conversion ratio (FCR), rate of egg production, egg size, egg mass, and several characteristics of eggs were determined at 4 and 8 wk. Venous blood was sampled at 4 and 8 wk for measurement of 5 biomarkers of health.

Results

The 15% DFA diet decreased (P <?0.05) feed intake, egg production, and plasma uric acid concentrations as compared with the control diet, but increased (P <?0.05) egg albumen weight and height compared with the 7.5% DFA diets. The two levels of DFA produced dose-dependent (P <?0.05) changes in three color measures of egg yolk, without affecting four hen plasma biochemical indicators of health.

Conclusions

Feeding laying hens with 7.5% DFA in the corn-soybean meal diet for 8 wk had no adverse effect on their health, egg production, or egg quality, but 15% inclusion reduced feed intake, egg production, and efficiency of feed utilization.     

Effects of main cereal type and feed form on production performance,egg quality and egg sanitary indices of laying hens

ABSTRACT

1. The experiment was conducted to evaluate the effects of cereal types (maize or wheat) and feed forms (pelleted or mash feed) on production performance, egg quality and egg sanitary indices in laying hens.

2. Three hundred and sixty hens (Jinghong No. 1) at 18 weeks of age were randomly assigned to four treatments with six replicates of 15 hens per replicate according to a 2 × 2 factorial design with two cereal types (maize or wheat) and two feed forms (pelleted or mash feed).

3. Compared with the wheat-based diet, the maize-based diet improved (P < 0.05) average egg weight of laying hens. Yolk colour of hens fed with the maize-based diet was higher (P < 0.05) in comparison to those fed the wheat-based diet, while Haugh units were lower (P < 0.05) for the maize-based treatment. Egg mass and average daily feed intake of hens fed the pelleted diet were higher (P < 0.05) than of those fed the mash diet. However, the mash diet improved (P < 0.05) yolk colour compared with the pelleted diet. The percentage of dirty eggs for the wheat-based diet was higher (P < 0.05) than for the maize-based diet. The percentage of dirty eggs was higher (P < 0.05) in birds fed the pelleted diet compared with those fed the mash diet. There were interactions (P < 0.05) between cereal type and feed form, with regard to average egg weight and shell thickness.

4. In conclusion, dietary cereal type affected average egg weight, yolk colour and Haugh units in eggs, while feed form influenced egg mass, average daily feed intake and yolk colour.     

Dynamics of amino acid and protein metabolism of laying hens after administration of 15N-labeled wheat protein. 6. 15N incorporation into the contents and tissue of segments of the gastrointestinal tract and into the pancreas

12 colostomized laying hens received, together with a conventional feed ration, 15N labelled wheat with a 15N excess (15N') of 14.37 atom-% over 4 days. 3 animals each were butchered after 12 h, 36 h, 60 h and 108 h after the last 15N' application and, apart from various organs, the contents and the tissue of the gastro-intestinal tract of each hen was divided into 3 fractions. TCA precipitation was carried out with the contents and the tissue of the 3 fractions. Nitrogen and its atom-% 15N' were determined in the supernatant and the precipitate. The 15N' amount in the contents of the crop and the stomachs, the small and large intestines is still considerable 12 h after the last 15N wheat feeding and still clearly detectable 108 h after it. The TCA precipitable amounts of 14N and 15N' of the contents of crop and stomach and that of the small intestine agree well; they are 75% and 50% resp. of the total N. The amount of atom-% 15N' of the contents of the small and large intestines remains the same up to 36 h after the last 15N' application and is higher at the following measuring points in the contents of the large intestine. A close correlation could be ascertained between the atom-% 15N' in the contents and tissue of the small and large intestines. The TCA soluble N quotas of both 14N and 15N' in the pancreas are higher than 50%.     

Enteric methane production and greenhouse gases balance of diets differing in concentrate in the fattening phase of a beef production system

The purposes of this study were 1) to assess the effects of 3 high-concentrate diets on enteric CH(4) production, total tract digestibility, and rumen fermentation of beef cattle, and 2) to evaluate, by life cycle assessment, the potential effects of these feeding systems on the environment. Six bulls (age of 12.4 mo and BW of 417 kg at midexperiment) of the Blond d'Aquitaine breed were assigned to 3 dietary treatments in a replicated 3 × 3 Latin square design. Diets consisted of 1) 49% natural grassland hay, 41% ground corn grain, and 10% soybean meal (hay); 2) 63% corn silage, 21% ground corn grain, and 16% soybean meal (CS); and 3) 70% ground corn grain, 16% soybean meal, and 14% wheat straw (CG). Daily CH(4) emission (g/d), measured using the sulfur hexafluoride tracer technique, was similar for the hay and CS diets and was 56% greater than for the CG diet (P < 0.001). This difference between diets was maintained when CH(4) output was expressed by unit of feed intake (P < 0.001) or digested feed (P < 0.001). Gross energy intake loss as CH(4) averaged 6.9% for the hay and CS diets and 3.2% for the CG diet (P < 0.001). Organic matter intake and GE intake did not differ between diets. Organic matter digestibility was less for the hay diet than for the CS and CG diets (P=0.008). Digestibility of NDF was greatest for the hay diet, intermediate for the CS diet, and least for the CG diet (P=0.02), with ADF digestibility being similar between the hay and CS diets and greater than for the CG diet (P < 0.001). The rumen pH at 5 h postfeeding was less for animals fed the CG diet compared with those fed the other 2 diets (on average, 5.1 vs. 5.9, respectively; P < 0.001). Total CH(4) emission (enteric + manure) was least for the CG diet, whereas N(2)O and CO(2) emissions were greatest for the CG diet. Total greenhouse gas emissions were least for the CG diet when C sequestration by grasslands was not taken into account.     

Hydrolysis of phytic acid by intrinsic plant or supplemented microbial phytase (Aspergillus niger) in the stomach and small intestine of minipigs fitted with re-entrant cannulas

Hydrolysis of phytate in the stomach and the small intestine as influenced by intrinsic plant (wheat) and supplemented microbial phytase (A. niger) were investigated with six minipigs (40-50 kg initial BW) fitted with re-entrant-cannulas in the duodenum, 30 cm posterior to the pylorus (animals 1, 4, 5, and 6) and ileocecal re-entrant cannulas, 5 cm prior the ileocecal junction (animals 1, 2, and 3), respectively. Dietary treatments were as follows: (1) diet 1, a corn-based diet (43 U Phytase/kg DM); (2) diet 2, diet 1 supplemented with microbial phytase (818 U/kg DM) and (3) diet 3, a wheat-based diet (1192 U/kg DM). At 0730 and 1930 per animal 350 g diet mixed with 1050 ml de-ionized water were fed. Digesta were collected continuously and completely during 12 h after feeding. Duodenal recovery of dry matter and total phosphorus were 100% in the period between two feedings, irrespective of dietary treatment. In animals fed the wheat-based diet, dry matter left the stomach faster (p < 0.05) during the first hour after feeding than in animals fed the corn-based diets (41.3 vs. 31.0 and 25.8% of intake, respectively). Supplemented microbial phytase did not affect ileal dry matter digestibility of the corn-based diet. In the first hour after feeding, phosphorus concentration of the duodenal digesta of animals fed corn-based diets with or without supplemented microbial phytase (5.86, 6.19 mg total P/g DM) exceeded the dietary level considerably (4.30 and 4.21 mg total P/g DM) indicating a higher solubility of corn than wheat phosphorus in the stomach. Apparent ileal P absorption was higher (p < 0.05) in the wheat-based diet (37.6%) and corn-based diet supplemented with microbial phytase (34.3%) than in the unsupplemented corn-based diet (17.6%).     

Influence of chromium tripicolinate on growth and glucose metabolism in yearling horses

Thoroughbred and Quarter Horse yearlings (n = 24; 335+/-7 d of age) were used in a 112-d feeding trial to determine whether chromium (Cr) supplementation would alter growth, development, and energy metabolism of growing horses on high-concentrate diets. The horses were assigned at random within breed and gender subgroups to one of four treatment groups: A) basal concentrate; B) basal plus 175 microg of Cr/kg concentrate; C) basal plus 350 microg of Cr/kg concentrate; and D) basal plus 700 microg of Cr/kg concentrate. Chromium was provided via Cr tripicolinate (Prince Agri Products, Quincy, IL). The horses were weighed, measured for withers and hip height, heart girth, and body length and underwent ultrasound evaluation for croup fat thickness. The concentrate was fed for ad libitum consumption for two, 1.5-hr feeding periods daily. Coastal bermudagrass (Cynodon dactylon) hay was group-fed (six animals/group) at 1% of BW daily. Feed intake was 60% concentrate and 40% hay, resulting in a supplemental Cr intake of 0, 105, 210, and 420 microg/kg diet for groups A, B, C, and D, respectively. Colts consumed more concentrate and total feed than did fillies (P < .05), but no dietary effect on feed intake was detected. Colts weighed more than fillies at the completion of the experiment (P = .0754), but no dietary effects on weight, body measurements, or croup fat were detected. An i.v. glucose tolerance test (.2 g of glucose/kg BW) and an i.v. insulin sensitivity test (.1 IU of insulin/kg BW) were conducted on each animal during the third 28-d period of the experiment. Plasma glucose peaked immediately following injection and decreased more rapidly in animals consuming the high-Cr diet than in those consuming the control diet (P < .01). Mean glucose fractional turnover rate values increased (P = .0369) and mean half-life of glucose decreased (P = .0634) in response to the high Cr supplementation. Plasma glucose depletions in animals fed the other two diets were between and not different from (P > .10) the depletions in control animals or in those fed high-Cr diets. No difference in insulin sensitivity was detected (P > .10). Results indicate that Cr tripicolinate supplementation of yearling horses increases the rate at which glucose is metabolized and may lower the plasma glucose concentration. No effect of Cr supplementation on development of the animals was detected.     

Influence of different levels of concentrate and ruminally undegraded protein on digestive variables in beef heifers

This experiment evaluated the effect of 2 levels of diet concentrate (20 and 40% of DM) and 2 levels of ruminally undegraded protein (RUP: 25 and 40% of CP) on nutrient intake, total and partial apparent nutrient digestibility, microbial protein synthesis, and ruminal and physiological variables. Eight Nellore heifers (233 +/- 14 kg of BW) fitted with ruminal, abomasal, and ileal cannulas were used. The animals were held in individual sheltered pens of approximately 15 m(2) and fed twice daily at 0800 and 1600 h for ad libitum intake. Heifers were allocated in two 4 x 4 Latin square designs, containing 8 heifers, 4 experimental periods, and 4 treatments in a 2 x 2 factorial arrangement. All statistical analyses were performed using PROC MIXED of SAS. Titanium dioxide (TiO(2)) and chromic oxide (Cr(2)O(3)) were used to estimate digesta fluxes and fecal excretion. Purine derivative (PD) excretion and abomasal purine bases were used to estimate the microbial N (MN) synthesis. No significant interaction (P > 0.10) between dietary levels of RUP and concentrate was observed. There was no effect of treatment (P = 0.24) on DMI. Both markers led to the same estimates of fecal, abomasal, and ileal DM fluxes, and digestibilities of DM and individual nutrients. Ruminal pH was affected by sampling time (P < 0.001), but no interaction between treatment and sampling time was observed (P = 0.71). There was an interaction between treatment and sampling time (P < 0.001) for ruminal NH(3)-N concentration. A linear decrease (P = 0.04) over sampling time was observed for the higher level of RUP, whereas a quadratic effect (P < 0.001) of sampling time was observed for the lower level of RUP. The higher level of dietary concentrate led to greater MN yield regardless of the level of RUP. The MN yield and the efficiency of microbial yield estimated from urinary PD excretion produced greater (P < 0.01) values than those estimated by either TiO(2) or Cr(2)O(3), which did not differ (P = 0.63) from each other. However, all methods yielded values that were within the range reported in the literature. In conclusion, no interactions between dietary levels of RUP and concentrate were observed for ruminal and digestive parameters. Neither RUP nor concentrate level affected DMI. Titanium dioxide showed to be similar to Cr(2)O(3) as an external marker to measure digestibility and nutrient fluxes in cattle.     

鲜饲金荞麦对热应激蛋鸡生产性能、蛋品质和血清指标的影响

本试验旨在研究鲜饲金荞麦对热应激条件下的长顺绿壳蛋鸡生产性能、蛋品质和血清指标的影响。采用完全随机试验设计,将300只鸡分为5个处理组:C组(基础饲粮)、T₁组(基础饲粮+5%金荞麦)、T₂组(基础饲粮+10%金荞麦)、T₃组(基础饲粮+15%金荞麦)和T₄组(基础饲粮+20%金荞麦),每个处理5个重复,每个重复12只鸡。将所有用于试验的鸡只暴露于(31.4±1.5) ℃的高温环境下发生自然热应激。记录和统计每月平均采食量、蛋重和产蛋数,并测定试验末各处理鸡蛋的表观品质、全蛋氨基酸和蛋黄脂肪酸含量,以及蛋鸡的血清激素水平、炎症因子和内毒素浓度。结果表明,T₁组在试验第2个月的产蛋率显著高于其余处理组(P<0.05),C、T₁和T₂的产蛋率在第3个月和全期差异不显著(P>0.05);C和T₁的蛋黄颜色等级显著低于其余处理组(P<0.05);T₃组全蛋中的异亮氨酸含量最高,T₃和T₄组的蛋氨酸含量较高(P<0.05),而C组的多不饱和脂肪酸显著高于其他处理组(P<0.05);C组蛋鸡的肾上腺皮质激素和皮质酮浓度显著高于试验组(P<0.05),相反,C组的皮质酮和黄体生成素显著低于试验组(P<0.05),试验组白细胞介素-6、肿瘤坏死因子α和血清内毒素均显著低于对照组(P<0.05)。因此,饲粮中添加10%的鲜饲金荞麦对热应激条件下长顺绿壳蛋鸡的平均产蛋率无负面影响,加深了蛋黄颜色;改善了全蛋氨基酸组成和含量,但对蛋黄脂肪酸组成有负面影响;提高了血清促卵泡素和黄体生成素含量;降低了血清炎症因子和内毒素水平。     

The effect of texturized vegetable protein containing soy carbohydrate on oroileal transit of chromic oxide in cannulated dogs

Texturized vegetable protein (TVP) from soy is widely used in dog foods but contains indigestible carbohydrate, which may affect intestinal transit. This study was conducted to determine whether TVP affects oroileal transit of the marker chromic oxide (Cr2O3). Four canned diets with Cr2O3 added were fed to eight cannulated mixed-breed dogs in a Latin-square design. The four diets contained reciprocal proportions of protein from TVP (0 to 57%) and from beef (100 to 43%). Ileal effluent was collected during wk 3 of each diet period, prececal apparent digestibility was measured on d 1 to 3 (eight dogs), and rate of appearance of Cr2O3 and chyme was measured on d 4 (six dogs). There was a postprandial delay before any chyme or Cr2O3 was collected, but from 2 to 8 h postprandially the rate of excretion was almost constant (approximately 11%/h). As TVP increased, mean prececal digestibility of protein and carbohydrate decreased from 77 to 71% and from 80 to 62%, respectively. Chyme excretion from 2 to 8 h postprandially increased from 5.8 to 8.3 g DM/h (P < .0001) as TVP increased but times for transit of Cr2O3 and appearance of chyme (as percentage total collected/hour) did not change. Mean times to first appearance and 15, 50, and 95% excretion were 76, 160, 347, and 707 min for Cr2O3 and 60, 147, 338, and 712 min for chyme, respectively. Mean Cr2O3 recovery was 93%. In conclusion, small intestinal transit of Cr2O3 was unaffected by increasing dietary TVP despite marked changes in carbohydrate digestibility.     

Effect of diet composition and feed intake level on diet digestibility and ruminal metabolism in growing lambs.

Lambs (29 +/- 2.5 kg) were fed three diets at various intakes to determine whether diet composition or level of intake was reflected in changes in diet digestibility or ruminal fluid characteristics. In Exp. 1, a 90% concentrated, pelleted diet or a whole shelled corn diet with a pelleted protein supplement was fed at three levels of intake: ad libitum and 92.5 and 85% of ad libitum (n = 15). Exp. 2 compared the 90% concentrate diet with diets in which the energy density was diluted to 55 or 72.5% concentrate by including alfalfa hay as a possible method of restricting energy intake (n = 6). Lambs were adapted to diets for 13 d; feces were collected for 6 d and ruminal fluid was collected 0, 3, and 6 h after feeding on the day following fecal collection. Restricting intake in Exp. 1 did not affect DM digestibility or digestibility of CP or starch. Digestibility of ADF was increased (P less than .10) by restricting intake. Ruminal fluid pH, ammonia concentration and VFA concentrations were affected little by either restricted intake level. Digestibility of DM was 4% higher (P less than .001) and starch 5% higher (P less than .001) for the whole shelled corn diet than for the pelleted, high-concentrate diet. Ruminal pH of lambs fed the whole shelled corn diet was higher and fluctuated less than the ruminal pH of lambs fed the high-concentrate, pelleted diet. In Exp. 2, diet digestibility was reduced (P less than .01) and ruminal pH was increased (P less than .002) by addition of hay. Restricted feeding of lambs did not seem to increase diet digestibility or alter ruminal conditions.     

Zinc bioavailability in soybean meal

A phytate-containing soy protein concentrate (SPC) diet (13.5 mg Zn/kg) and a phytate-free egg white diet (.3 mg Zn/kg) were used to determine the relative bioavailability (RBV) of Zn in dehulled soybean meal (SBM) based on Zn depletion-repletion growth bioassays in young chicks. After a 4-d Zn depletion period, chick weight gain responded linearly (P < .01) to graded increments of supplemental Zn (0 to 10 mg/kg) from ZnSO4 x 7H2O, whether added to the Zn-deficient SPC or egg white diet. Slope, however, was over twice as great for the standard curve relating weight gain to supplemental Zn intake for the egg white diet as for the SPC diet. Addition of 7 to 10 mg Zn/kg from SBM to either Zn-deficient diet increased (P < .01) weight gain, but a similar SBM addition to either diet made adequate in Zn did not increase weight gain. Using standard-curve methodology, RBV of Zn in SBM was 78% when the the SPC diet was used, but it was only 40% when the egg white diet was used. The phytate contained in the SPC basal diet therefore markedly reduced the efficiency of utilizing the supplemental inorganic Zn from ZnSO4 x 7H2O. This lowered the slope of the standard curve so that, on a relative basis, the Zn in SBM had a higher RBV value than was the case for Zn utilization in SBM with the phytate-free egg white diet. The 78% Zn RBV value in SBM would seem to have the greatest relevance for practical-type corn-SBM diets.