Threonine requirement for reproduction in swine

An experiment was conducted to estimate the threonine requirement of pregnant swine. L-threonine was added to a fortified corn-gelatin diet and fed at a rate to provide five threonine levels of 3.59, 4.95, 6.31, 7.67 and 9.03 g/d. Twenty-five crossbred gilts were randomly assigned to these five dietary treatments. Increasing threonine resulted in a difference (P less than .01) in nitrogen (N) retention, with maximum retention at 4.95 g/d threonine intake. Blood samples were drawn before and after feeding. Although plasma urea N did not change significantly, the lowest level occurred at an intake of 4.95 g/d threonine. As threonine intake increased, plasma threonine increased quadratically (P less than .05). This increase was accompanied by a quadratic (P less than .005) decrease in plasma lysine. Sow weight gains increased quadratically (P less than .01) with increasing threonine levels. Litter weight, number of pigs born, baby pig gains, daily milk yield and milk protein were not influenced by threonine levels. The lysine-alpha-ketoglutarate reductase activity of the sow liver samples increased linearly (P less than .05) as dietary threonine levels increased. Based upon metabolic criteria 4.95 g/d L-threonine met the requirement for animals in this experiment. If 75% of threonine in a corn-soybean meal diet is available, the threonine requirement for reproduction would be no higher than 5.4 g/d or .30% dietary threonine when daily feed intake is 1.82 kg.     

Threonine requirement of pigs weighing 5 to 15 kg

Weanling crossbred pigs (avg initial wt 6.4 kg) were fed diets containing six levels of threonine to determine the threonine requirement of young pigs fed diets somewhat similar to those used in commercial swine production. The diets (16% crude protein) were composed primarily of grain sorghum, oat groats and soybean meal supplemented with minerals, vitamins, lysine, tryptophan, methionine and isoleucine, and were calculated to be adequate in all nutrients except threonine and crude protein. Threonine levels were .53, .57, .62, .68, .75 and .83% of the diet. There were two trials, each with 96 pigs. The pigs were fed the experimental diets for 28 d. The addition of threonine increased weight gain (P less than .02) and feed efficiency (P less than .001), with most of the response occurring between .53 and .68% threonine. There was little further response when threonine was increased above .68%. Plasma threonine concentrations increased as dietary threonine increased, with a sharp rise when dietary threonine exceeded .68%. Concentrations of most other essential amino acids in the plasma declined in response to increasing dietary threonine, and reached minimum values at either .68 or .75% threonine. Plasma urea concentrations decreased as threonine was increased in the diet, reaching a plateau at .68% dietary threonine. The data indicate the young pigs weaned at 3 to 4 wk of age require approximately .70% threonine.     

Maximal portion of the young pig's sulfur amino acid requirement that can be furnished by cystine.

Three pig experiments were conducted using a chemically defined, amino acid diet under conditions in which all nutrients were 100% bioavailable to assess the maximal portion of the sulfur amino acid (SAA) requirement that could be furnished by cystine (Cys). In Exp. 1, a methionine (Met)-deficient diet containing .12% L-Met and .40% L-Cys was supplemented with graded levels of L-Met. Pigs weighing 10 kg initially responded quadratically (P less than .05) to Met supplementation. A two-slope, broken-line regression model (weight gain regressed on percentage of dietary Met) estimated an infection point at .23% dietary Met. A constant level of .46% dietary SAA with differing Met:Cys weight (wt:wt) ratios was used in Exp. 2. Pigs fed Met:Cys ratios of 60:40 and 50:50 had similar (P greater than .05) weight gains, but pigs fed a 40:60 Met:Cys ratio gained less (P less than .05) than those fed the other diets. Maintaining dietary sulfur at .111% in Exp. 3, pigs fed Met:Cys ratios (wt:wt) of 100:0, 55:45, 50:50, and 45:55 gained weight at similar (P greater than .05) rates, but pigs fed the 45:55 Met:Cys ratio had a tendency to produce lower weight gains. Regardless of whether a constant dietary SAA or sulfur level was maintained, no more than 50% of the young pig's total SAA requirement (wt:wt) could be furnished by Cys.     

Methionine requirement of pigs between 5 and 20 kilograms body weight.

Four nursery experiments were conducted using a methionine (Met)-deficient feather meal-corn-soybean meal-dried whey basal diet (20% CP; 3,250 kcal of ME/kg, .11% choline, .19% Met, 1.00% cystine) supplemented with lysine, tryptophan, and histidine to determine the Met requirement of 5- to 10- and 10- to 20-kg pigs. Based on a true Met digestibility value of 81.6% estimated by a pig ileal digestibility assay, the Met-deficient basal diet contained .155% of digestible Met. A preliminary experiment (Exp. 1) indicated that pigs fed the Met-deficient basal diet when fortified adequately with Met could produce weight gains similar to those of pigs fed a 20% CP practical corn-soybean meal-dried whey diet. In Exp. 2 and 3, crossbred pigs weighing 5.8 kg initially were fed diets containing graded levels of digestible Met between .195 and .355%. Average daily gain increased quadratically (P less than .05) as the level of Met increased. When the data of Exp. 2 and 3 were examined together, the digestible Met requirement of 5- to 10-kg pigs was estimated to be .255% of the diet. In Exp. 4 and 5, crossbred pigs averaging 10 kg were fed digestible Met concentrations ranging from .155 to .315%. Average daily gain increased quadratically (P less than .05). The digestible Met requirement of 10- to 20-kg pigs was estimated at .255% for maximal weight gain, which was similar to that of 5- to 10-kg pigs. Assuming an 89% digestibility of Met in practical corn-soybean meal diets, the total Met level needed in practice would be .29%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Utilization by growing and finishing pigs of raw soybeans of low Kunitz trypsin inhibitor content

Three trials were conducted to compare acceptance and utilization by growing and finishing pigs of diets containing supplemental protein from either heated, solvent-extracted soybean meal (SBM), raw low-Kunitz trypsin inhibitor soybean (LT) or raw commercially grown Williams cultivar soybean with high Kunitz trypsin inhibitor content (HT). In Trial 1, 36 crossbred pigs, averaging 7 kg in weight, were fed 1) corn-SBM, 2)corn-LT or 3) corn-HT diets for 28 d. Diets were formulated to be isolysinic and to have similar calorie:lysine ratios. Average daily gain and gain/feed were higher (P less than .01) for pigs fed the corn-SBM diet than for pigs fed the corn-LT diet; average daily gain and gain/feed were higher (P less than .01) for the corn-LT diet than for the corn-HT. Average daily feed intake did not differ (P greater than .05) among diets. In Trial 2, 48 crossbred pigs averaging 67 kg were fed diets similar to those in Trial 1 but with lower lysine values. The daily gain (.95 kg) of pigs fed the corn-SBM diet was greater (P less than .05) than for pigs fed the corn-LT diet (.87 kg), which in turn was greater (P less than .05) than for the pigs fed the corn-HT diet (.83 kg). Daily feed intake (kg) and gain/feed were 3.27 and .291, 2.97 and .293, and 3.07 and .270, respectively, for pigs fed the corn-SBM, corn-LT and corn-HT diets. In Trial 3, 18 castrate male pigs averaging 12.4 kg were fed cornstarch-based diets with either SBM, LT or HT as the source of protein.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transient hypersensitivity to soybean meal in the early-weaned pig

An experiment was conducted to determine whether baby pigs develop hypersensitivity to dietary soybean proteins. Thirty-two pigs were orally infused with either dried skim milk (5 g/d; control) or soybean meal (48% CP; 5 g/d) from d 7 to 14 after birth. Sows were fed a corn-corn gluten meal-based diet supplemented with lysine and tryptophan to avoid exposure of pigs to soybean proteins. Pigs were weaned at 21 d of age and fed diets containing either soybean meal or milk proteins until d 56. One half of the pigs were killed at 28 d of age and the rest at 56 d of age. Segments of small intestine were collected, and intraepithelial lymphocytes were isolated. At 28 d of age, pigs fed diets containing soybean meal had lower (P less than .05) villus height (221 vs 298 microns) and rate of gain (86 vs 204 g/d) than control pigs did. Pigs fed a diet containing soybean meal had higher (P less than .05) immunoglobulin G (IgG) titers to soybean protein than did pigs fed a milk protein-based diet. Blood and intestinal lymphocytes collected on d 28 and 56 did not exhibit any proliferative response when cultured with purified soy proteins (2.5 or 5 microns/ml). Phytohemagglutinin- and pokeweed mitogen-induced lymphocyte proliferations were higher (P less than .05) at d 56 than at d 28, but there were no differences attributable to protein source. There were no differences (P greater than .05) in skin-fold thickness measurements following intradermal injection with soy or milk proteins. Decreased villus height and increased serum IgG titers to soybean proteins coinciding with inferior performance of early weaned pigs fed diets containing soybean meal indicate that conventionally processed, commercial soybean meal may retain some antigens that can cause transient hypersensitivity in piglets.     

Methionine, choline and sulfate interrelationships in the diet of weanling swine

Experiments were conducted to examine the interrelationships between methionine, choline and inorganic sulfate in the diet of weanling pigs, and to evaluate the selenium (Se) status of pigs fed diets with or without supplemental sulfate. Two trials utilized 288 weanling (3-wk-old) pigs allotted to dietary treatment based on weight, sex and litter origin. There were six pigs/pen and three replicate pens/treatment in each trial. The basal corn-soybean meal diet was formulated to supply .55% sulfur amino acids and contained a choline and sulfur-free vitamin and mineral premix. Lysine was added to provide a total of 1.13% lysine. Seven additional treatments were formulated by substituting for corn .17% DL-methionine, .29% choline dihydrogen citrate or .25% Na2SO4 to create a 2(3) factorial arrangement of treatments. There were methionine X choline X sulfate interactions for average daily gain (P less than .001) and feed-to-gain ratio (F:G; P less than .05). Adding choline, methionine, Na2SO4 or choline plus methionine to the basal diet did not improve gains. However, when Na2SO4 plus methionine or Na2SO4 plus choline were added, daily gains were increased (P less than .05) and F:G was improved (P less than .1). Addition of all three supplements did not result in a further increase in gain. Pigs fed choline-supplemented diets had higher (P less than .01) hematocrit and tended (P = .07) to have increased hemoglobin concentration. There was no effect on serum triglycerides or alkaline phosphatase activity due to dietary treatment. The concentration of Se in muscle, liver, kidney and blood was not influenced by sulfate content of the diet.     

Influence of dietary crude protein on peanut skin digestibility and utilization by feedlot steers

Peanut skins were fed at 15% of steer diets in metabolism and feedlot trials. Elevation of dietary protein using soybean meal or soybean meal plus urea and ammoniation of skins were evaluated as methods of overcoming detrimental performance and digestibility effects of tannins in peanut skins. Digestibility of dry matter, crude protein and energy were not different (P greater than .05) for steers fed a control diet with 11.4% crude protein with no skins compared with high-protein 15% peanut skin diets with soybean meal (15.5% crude protein) or soybean meal plus urea (16% crude protein). Dry matter, crude protein and energy digestibilities of control and of high-protein peanut skin diets were higher (P less than .05) compared with an 11.4% crude protein peanut skin diet and a 12.2% crude protein diet with ammoniated peanut skins. Ether extract digestibility was higher (P less than .05) for all peanut skin diets compared with the control. Nitrogen retention (g/d) was not different (P greater than .05) for control and high-protein peanut skin diets, and nitrogen retention on these diets was higher (P less than .05) compared with the lower protein and ammoniated peanut skin diets. Diets fed in the metabolism trial, except for the ammoniated peanut skin diet, were fed to 96 steers (345 kg initial wt) in a 109-d feedlot trial. Performance was lower (P less than .05) for steers fed the lower-protein peanut skin diet compared with other treatments through d 56; this diet was discontinued as a treatment on d 62.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nutritional value of quality protein maize and food corn for starter and growth pigs

Growth traits with starter and grower pigs and a digestion trial were conducted to compare the nutritional value of Quality Protein Maize (QPM), food corn and conventional feed corn. The QPM, food and feed corn contained .45, .31 and .29% lysine, respectively. The growth trials evaluated a QPM-soybean meal diet formulated on a lysine basis (.96% in starter and .7% in grower diets) and four diets arranged in a 2 (food corn vs feed corn) X 2 (low vs high soybean meal) factorial. Soybean meal was either added in the same amount as in the QPM diet or was added to provide the lysine content of the QPM diet. Performance was similar for pigs fed food corn and feed corn in both trials. The QPM diets resulted in greater performance than food and feed corn diets containing the same level of soybean meal supplementation; starter pigs were more (P less than .10) efficient and grower pigs had a higher (P less than .01) rate and efficiency of gain. However, performance of pigs fed the QPM diets was not equal to that of pigs fed isolysinic food and feed corn diets; growth rate was lower (P less than .05) in starter pigs and gain:feed was lower (P less than .05) in grower pigs. Diets in the digestion trial consisted of the corns plus 3.25% casein. Energy digestibility was similar for all diets. Ileal N and amino acid digestibilities were highest for QPM, intermediate for food corn and lowest for feed corn. In most instances, these differences were significant (P less than .05). Apparent biological value was highest (P less than .05) for QPM. These trials indicate that food corn and feed corn have similar nutritional value, and that starter and grower pigs can benefit from the higher protein quality of QPM.     

Methionine requirement of the finishing pig

Two pig experiments were conducted using a methionine (Met)-deficient feather meal-corn-soybean meal basal diet (13% CP; 3,400 kcal ME/kg diet, .126% Met, 456% cystine) supplemented with an amino acid mixture (lysine, tryptophan, histidine, threonine and phenylalanine) to determine the Met requirement of finishing pigs between 50 and 80 kg live weight. Using young chicks in a Met bioavailability growth assay and cecectomized adult cockerels in a Met digestibility assay, the Met-deficient basal diet was found to contain .115% bioavailable and .110% digestible Met. These results gave a bioavailability estimate (relative to DL-Met set at 100%) of 91.3 +/- 2.5% and a true digestibility estimate of 87.0 +/- 2.2% for Met in the basal pig diet. In Exp. 1, 21 crossbred pigs averaging 61 kg initially were individually fed diets containing .115, .165 or .215% bioavailable Met for 21 d. Average daily gain and gain:feed ratio increased quadratically (P less than .05) as level of Met increased. In Exp. 2, 30 crossbred pigs averaging 53 kg were individually fed diets containing .115, .135, .155, .175 or .195% bioavailable Met for 27 d. Daily gain and gain;feed ratio responded linearly (P less than .01) as Met level increased. Based on the results of Exp. 2, the bioavailable Met requirement of finishing pigs in the weight range 50 to 80 kg was estimated to be .182% of the diet. Assuming an 88% bioavailability of Met in commercial diets based on corn and soybean meal, the total Met level needed in practice would be .207%. If 55% of the finishing pig's sulfur amino acid need can be furnished by cystine, the total sulfur amino acid requirement would be .45% of the diet.     

Dietary protein level and ruminal degradability for mohair production in Angora goats.

Twenty-eight Angora goat doelings (average BW 22.1 kg) were used in a 150-d study to examine the effects of dietary CP level and degradability on mohair fiber production. A 2 x 2 factorial arrangement was instituted using conventional, solvent-extracted soybean meal (high degradability) or expelled, heat-treated soybean meal (low degradability) incorporated into low- (12%) or high- (19%) CP diets. Grease and clean mohair weights were greater (P less than .05) in goats fed the diets containing 19% CP. Mohair fiber diameter was not affected (P greater than .10) by dietary CP level. Clean mohair weight tended (P less than .08) to be higher in the goats fed diets containing expelled, heat-treated soybean meal. Body weight gains were not affected (P greater than .10) by CP level or degradability, whereas DMI increased (P less than .01) with increasing CP level. Ruminal fluid pH and total VFA concentrations were not affected (P greater than .10) by diet. Ruminal ammonia N concentration increased (P less than .05) as CP level in the diet increased, and postprandial changes in concentrations were less noticeable in the group fed expelled, heat-treated soybean meal. Plasma urea N (P less than .001) and total protein (P less than .01) concentration increased as dietary CP level increased. Plasma glucose was elevated (P less than .001) 2 h after feeding in the goats fed conventional, solvent-extracted soybean meal, whereas glucagon concentrations were greater at 0 and 4 h in the group fed expelled, heat-treated soybean meal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Digestible tryptophan requirements of starting, growing, and finishing pigs.

Seven hundred eight crossbred pigs were used in growth and digestion trials to determine the digestible tryptophan (Trp) requirement of starting (6 to 16 kg), growing (22 to 50 kg), and finishing (55 to 97 kg) pigs. Each growth trial evaluated a corn-fish meal-corn gluten meal basal diet, the basal diet with five incremental additions of L-Trp, and a control corn-soybean meal diet. The tryptophan content of the six incremental diets ranged from .13 to .255% for starting pigs, .08 to .18% for growing pigs, and .063 to .163% for finishing pigs. Lysine contents of basal diets were 1.38, .90, and .72% for starting, growing, and finishing diets, respectively. In all trials, ADG, ADFI, and gain/feed increased (P less than .001) linearly and quadratically as dietary Trp increased. Broken-line regression analyses determined the total dietary Trp requirements needed to optimize performance to be .19, .13, and .09% (as-fed basis) for starting, growing, and finishing pigs, respectively. These concentrations equated to Trp intakes of .96, 2.18, and 2.88 g/d. A digestion trial using growing pigs (29 kg initially) determined the apparent ileal digestibility of Trp in the basal starting and growing diets to be 72 and 70%, respectively; a similar trial with finishing pigs (55 kg initially) found 59% Trp digestibility for the basal finishing diet. Mean digestibility of L-Trp was 97%. Based on these values and the total Trp requirements given above, the digestible Trp requirements are .15, .10, and .06% for starting, growing, and finishing pigs, respectively.     

Nutritional value of quality protein maize for starter and finisher swine.

Growth trials with starter (n = 120, 6.8 kg initially, 28 d of age, Exp. 1) and finisher (n = 70, 59 kg initially, Exp. 2) pigs were conducted to compare quality protein maize (QPM, .40% lysine) and normal corn (.31% lysine) in simple corn-based diets containing the same levels of soybean meal. In Exp. 1, pig performance was similar (P greater than .10) on all diets, regardless of the level of soybean meal, suggesting that QPM and normal corn have similar feeding value in lysine-adequate (.99 to 1.11%) diets. In Exp. 2, less soybean meal was needed in QPM than in normal corn diets to maximize performance; increasing soybean meal from 10.8 to 13.8% improved rate (P less than .05) and efficiency (P less than .01) of gain of pigs fed normal corn diets but had no effect on performance of pigs fed QPM diets. A QPM-based diet containing 6% soybean meal and supplemental lysine and tryptophan failed to maximize feed efficiency, but growth rate was equal to that obtained on the normal corn diet with 13.8% soybean meal. The apparent fecal digestibility of GE and ileal digestibility of N were similar for QPM and normal corn, but apparent ileal digestibility of most essential amino acids was slightly higher for QPM (Exp. 3). Experiment 4 compared apparent digestibilities of QPM, conventional opaque-2 corn and two high-protein corns. Digestibilities differed (P less than .05) among the corns, but the absolute differences were small and were likely due to differences in amino acid content of the corns.(ABSTRACT TRUNCATED AT 250 WORDS)     

Digestible lysine requirement of starter and grower pigs

Three experiments were conducted to determine the digestible lysine requirement of starter (6 kg BW initially) and of grower (21 kg BW initially) pigs. Experiment 1 used 294 starter pigs and lasted 28 d; Exp. 2 used 182 grower pigs and lasted 35 d. Protein and total lysine contents of the basal corn-peanut meal diets were 20 and .8% for Exp. 1 and 16 and .54% for Exp. 2. Basal diets were fortified with five incremental additions of lysine.HCl to provide lysine contents ranging from .8 to 1.3% in Exp. 1, and .54 to .94% in Exp. 2. Diets contained crystalline tryptophan, threonine and isoleucine (Exp. 1 only) to provide dietary concentrations equal to 18, 70 and 60% of the highest lysine level fed. Average daily gain and gain/feed of both starter and grower pigs increased (P less than .05) linearly and quadratically as dietary lysine level increased. For starter pigs, ADG and gain/feed were optimized at 1.1 to 1.2% total lysine. For grower pigs, ADG and gain/feed were optimized at .86% total lysine. In Exp. 3, barrows fitted with an ileal T-cannula were used in a 4 X 4 Latin square design. Basal diets and diets with added lysine were evaluated. Apparent lysine digestibility of the basal starter and grower diets and lysine.HCl were 79.9, 74.1 and 96.7%, respectively. Based on these values and the total lysine contents found to optimize performance, the digestible lysine requirements of starter and grower pigs are 1.03 and .71%, respectively.     

Effects of graded levels of lysine and excess arginine and threonine on young pigs fed practical diets

Three experiments were conducted to estimate the lysine requirement of the weanling pig and the effects of excess arginine and threonine on that estimate. Feeding 1.15% dietary lysine in Exp. 1 and 1.20% in Exp. 2 maximized feed efficiency and resulted in the lowest plasma urea N values. Adding .15% threonine to the diets in Exp. 2 did not affect (P greater than .10) performance of the pigs, but increased (P less than .01) plasma urea N and decreased (P less than .01) plasma lysine concentrations. Supplemental arginine (.22%) did not affect performance of the growing pigs in Exp. 3, but it increased (P less than .01) plasma urea N. Pigs fed a corn-soybean meal diet utilized feed more efficiently (P less than .05) than those fed a corn-fish meal-dried whey diet. The most likely cause for this response was that the corn-soybean diet contained more lysine (.82%) than expected, whereas the corn-fish meal-dried whey diet had close to the expected content of lysine (.72%). From these results, it was concluded that the lysine requirement of the weanling pig fed practical diets is at least 1.15 or 1.20% of the diet. Also, added arginine or threonine did not adversely affect the performance of pigs.     

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 extrusion on the ileal and fecal digestibilities of lysine in yellow corn in diets for young pigs

Forty crossbred barrows (initial avg BW of 20 kg) were fitted with T-cannulas to determine the effects of extrusion of yellow corn on lysine digestibility. A basal corn-cornstarch-soybean meal diet was formulated to contain .55% lysine. Extruded corn (EC), non-extruded corn (C) and L-Lysine-HCl (LLH) replaced cornstarch in the basal diet to provide total dietary lysine levels of .60, .65 and .70% lysine for each lysine source. Diet intake was 5.5% of BW. Treatments were arranged as a 3 x 3 factorial with the basal diet as an extra dietary treatment. Apparent ileal digestibilities of lysine, threonine, methionine and isoleucine were greater (P less than .05) for diets with added LLH than for diets containing EC or C, which were similar (P greater than .05). Apparent ileal and fecal digestibilities and retention of nitrogen (N) as a percentage of N absorbed or consumed were greater (P less than .05) for diets containing LLH than for those containing EC or C, which were not different (P greater than .05). Plasma urea N levels were also lower (P less than .05) for pigs fed diets containing LLH than for pigs fed EC or C. Fecal DE and ME as a percentage of GE were greater (P less than .05) in diets containing EC than in those containing C. In summary, extrusion improved (P less than .05) energy utilization but did not affect the utilization of lysine or N in corn by pigs. However, lysine and N utilization were greater (P less than .05) in diets supplemented with LLH compared with EC or C.     

Effects of protein and carbohydrate sources on digestibility and digesta flow rate in weaned pigs fed a high-fat, dry diet

Two trials were conducted to evaluate the effects of protein source (48% CP soybean meal or casein) and carbohydrate source (25% dextrose or 25% lactose) on digestibility and digesta flow rate in early-weaned pigs. Diets contained 10% crude soybean oil and were formulated to contain 3.5 g lysine, 2.3 g Ca and 2.0 g P per 1,000 kcal DE of diet. In Trial 1, nutrient digestibility was greater for older than for younger pigs. Apparent digestibilities for energy, DM, CP and fat were lower (P less than .08) for younger and older pigs fed soybean meal rather than casein. Digestibility of soluble carbohydrates was less (P less than .02) for younger pigs fed soybean meal rather than casein as a protein source. Fat digestibility was lower (P less than .05) in younger pigs fed dextrose than in pigs fed lactose. A protein X carbohydrate source interaction (P less than .01) existed for fat digestibility by older pigs. In Trial 2, pigs were euthanatized, and digestibilities anterior to the ileum and the colon (pre-ileal and pre-cecal) were determined. At the ileum, fat digestibility was lower (P less than .05) for pigs fed soybean meal, whereas CP digestibility was lower (P less than .05) for pigs fed either soybean meal or dextrose. A protein X carbohydrate interaction was observed for ileal digestibilities of DM (P less than .06) and total carbohydrates (P less than .03) with lowest values obtained for the soybean meal plus dextrose diet. For casein diets, digestibility values were similar between the two carbohydrate sources.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of feeding Sarsaponin in cattle and swine diets

In four trials, steer calves were received in the feedlot, processed and fed diets supplemented with soybean meal (SBM), 1% urea (UR) or 1% urea plus sarsaponin (S) over a 28-d period. In trials 1 and 2, the feeding period was extended to approximately 62 d, in which steers were fed a common (SBM) diet the last 34 d. In trials 3 and 4, a SBM plus S diet treatment was included. During the first 28 d (four trial summary) daily gains of steers fed urea plus S (.74 kg) were intermediate to and significantly different from gains of steers fed SBM (.84 kg) or UR (.66 kg) diets. However, at the end of the 62-d feeding period (two trial summary) daily gains, feed intakes and feed efficiency did not differ (P greater than .05) among treatments. No significant improvements in performance were found in steers fed SBM diets supplemented with S. In swine trials, pigs were fed diets containing no additive, 63 mg S X kg-1, 55 mg chlortetracycline (C) X kg-1 or S plus C in a grower-finisher (GF) and grower (G) trial. In the GF trial, overall efficiency of feed conversion was improved (P less than .05) by feeding S or S plus C. In the G trial, daily gains and intakes were greatest for pigs fed S plus C and differed (P less than .1) from those of pigs fed S or C in the diet. Compared with feeding S or C alone, gain and intake of growing pigs were stimulated to a greater extent when S was fed in combination with C. Feeding S with or without C improved efficiency of feed conversion in finishing pigs.     

Effects of excess arginine on swine growth and plasma amino acid levels

One hundred seventy-six crossbred weaned pigs (4 to 5 wk old) were used in two growth trials to determine the effect of excess arginine on pig growth and plasma amino acid levels. In the first 28-d growth trial, two lysine levels (1.03 and 1.26%) and three arginine levels (.94, 1.29 and 1.63%) were used in a nested treatment arrangement. Lysine supplementation improved daily gains (P less than .05), tended to improve feed efficiency (P less than .12) and caused a general reduction in plasma essential amino acid levels. Arginine had no effect on daily gain or feed intake, but pigs fed 1.03% lysine and 1.63% arginine had reduced gain/feed (P less than .05). Arginine did not affect gain/feed of pigs fed 1.26% lysine. Plasma lysine levels were reduced (P less than .06) by excess arginine in pigs fed 1.26% lysine, but not in pigs fed 1.03% lysine. The four treatments for the second 26-d growth trial consisted of three diets containing .92% lysine and either .72, 1.10 or 1.61% arginine and a positive lysine control (1.10% lysine, .72% arginine). Lysine was the limiting amino acid in the basal diet, but arginine had no effect on daily gain, daily feed intake, gain/feed or plasma lysine levels. Plasma threonine and methionine levels were reduced by excess arginine in both experiments, while the other plasma essential amino acid levels were not affected by dietary arginine. Conclusions are that large excesses of added arginine may affect lysine utilization, but pig performance was affected only when excess arginine was combined with a lysine deficiency. The arginine levels similar to those found in grain-soybean meal swine diets had no effect on pig performance in these experiments.