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A regional experiment was conducted at 8 experiment stations, with a total of 320 sows initially, to evaluate the efficacy of adding 13.35% ground wheat straw to a corn-soybean meal gestation diet for 3 successive gestation-lactation (reproductive) cycles compared with sows fed a control diet without straw. A total of 708 litters were farrowed over 3 reproductive cycles. The basal gestation diet intake averaged 1.95 kg daily for both treatments, plus 0.30 kg of straw daily for sows fed the diet containing ground wheat straw (total intake of 2.25 kg/d). During lactation, all sows on both gestation treatments were fed ad libitum the standard lactation diet used at each station. Response criteria were sow farrowing and rebreeding percentages, culling factors and culling rate, weaning-to-estrus interval, sow BW and backfat measurements at several time points, and litter size and total litter weight at birth and weaning. Averaged over 3 reproductive cycles, sows fed the diet containing wheat straw farrowed and weaned 0.51 more pigs per litter (P

Ten sets of 5 littermate pigs from each of 2 genetic strains were utilized to determine the impact of the dietary concentration of 5 B vitamins (riboflavin, niacin, pantothenic acid, cobalamin, and folacin) on growth from 9 to 28 kg of BW in pigs with high or moderate capacity for lean growth. All pigs (penned individually) were reared via a segregated, early weaning scheme, so that the lean growth potential of each strain could be expressed. The basal diet provided the 5 test vitamins at concentrations of total and estimated bioavailability equivalent to a minimum of 100 and 70%, respectively, of their estimated requirements (NRC, 1998) for 5- to 10-kg pigs. At a BW of 9 +/- 0.9 kg, pigs within each litter were allotted to the basal diet supplemented with sources of the 5 test vitamins equivalent to an additional 0, 100, 200, 300, or 400% (bioavailable) of the NRC requirements. Pigs from the high lean strain consumed less feed (P < 0.05) and gained BW faster (P < 0.02) and more efficiently (P < 0.01) than pigs of the moderate lean strain. In both lean strains, the rate and efficiency of growth were improved (P < 0.01) as dietary B vitamin concentrations were increased. However, the dietary B vitamin concentrations needed to optimize G:F were greater (P < 0.03) in the high (>470% of NRC, 1998) vs. moderate (270%) lean strain. Based on these data, the dietary needs for 1 or more of the 5 B vitamins are greater than current NRC (1998) estimates, particularly in pigs expressing a high rate of lean tissue growth. The greater need for these vitamins is not associated with greater dietary energy intake or body energy accretion rate but is potentially due to shifts in the predominant metabolic pathways.

An experiment involving 25 experiment stations in the North Central and Southern regions (NCR-42 and S-288, respectively) was conducted to assess the degree of uniformity of diet mixing among stations and to assess the variability among station laboratories in chemical analysis of mixed diets. A fortified corn-soybean meal diet was mixed at each station using a common diet formula (except for vitamin and trace-mineral additions). The diet was calculated to contain 14% crude protein (CP), 0.65% Ca, 0.50% P, and 125 ppm Zn (based on 100 ppm added Zn). After mixing, samples were collected from the initial 5% of feed discharged from the mixer, after 25, 50, and 75% was discharged, and from the final 5% of discharged feed. The five samples were sent to the University of Kentucky, finely ground, and divided into subsamples. Each set of five subsamples from each station was distributed to three randomly selected stations for analysis of CP, Ca, P, and Zn (i.e., each station analyzed five diet sub-samples from three other stations). In addition, two commercial and two station laboratories analyzed composites of the five subsamples from each of the 25 mixed diets. Based on the laboratories that analyzed all diets, means were 13.5, 0.65, and 0.52%, and 115 ppm for CP, Ca, P, and Zn, respectively. Ranges of 11.8 to 14.6% CP, 0.52 to 0.85% Ca, 0.47 to 0.58% P, and 71 to 182 ppm of Zn were found among the 25 diet mixes. The coefficients of variation among the 25 diet samples for CP, Ca, P, and Zn were 4.3, 9.3, 4.1, and 17.4%, and among the 25 laboratories were 3.6, 12.5, 10.7, and 11.1%, respectively. Overall analyses of the five sub samples were, respectively, CP: 13.4, 13.6, 13.4, 13.5, and 13.4% (P < 0.06); Ca: 0.66, 0.67, 0.67, 0.66, and 0.67%; P: 0.50,0.51,0.51,0.50, and 0.50%; and Zn: 115, 116, 112, 113, and 120 ppm (P < 0.001). Diets were not uniformly mixed at all stations (station x sample No. was P < 0.08 for Ca and P < 0.01 for CP, P, and Zn). Among stations, the range of the five samples, expressed as a percentage of the mean and averaged for CP, Ca, P, and Zn, varied from +/- 1.1% (i.e., 98.9 to 101.0%) to +/- 12.9% (84.6 to 110.4%), with an overall average of +/- 5.2%. Neither type nor volume of mixers was related to mixing uniformity. The results suggest that uniformity of diet mixes varies among experiment stations, that some stations miss their targeted levels of nutrients (especially Zn), and that the variability among experiment station laboratories in analysis of dietary Ca, P, and Zn in mixed diets is quite large.

The objective of this study was to determine the effect of short-term feeding of vitamin D3 (D3) on blood plasma calcium concentrations and meat quality of pork-loin chops. Three experiments were carried out to meet this objective. Experiment 1 used 250,000 IU and 500,000 IU/d to determine the effective dose of dietary D3 to raise blood plasma calcium concentration. Experiment 2 used 500,000 IU D3/d to determine the appropriate length of feeding time to elevate blood plasma calcium prior to harvest. Experiment 3 used 500,000 IU D3/d to determine the effectiveness of increased blood plasma calcium in improving postmortem quality and tenderness of pork-loin chops. Pigs fed 500,000 IU D3/d in Exp. 1 exhibited higher (P < 0.05) and more stable plasma calcium concentration over a 14-d feeding trial compared with pigs fed 250,000 IU D3/d and control pigs. Therefore, 500,000 IU D3/d was the dose chosen for Exp. 2, in which pigs fed 500,000 IU D3/d for 3 d prior to harvest exhibited elevated and stable plasma calcium concentrations; this length of time was deemed sufficient in which to observe differences in postmortem meat tenderness in Exp. 3. Vitamin D3 supplementation resulted in lower (P < 0.02) L* values and higher (P < 0.03) a* values of loin chops at 7 and 14 d of shelf storage. Vitamin D3 supplementation did not affect quality characteristics (measured by use of subjective scores) or tenderness (quantified via Warner-Bratzler shear force or Star probe values). On the basis of these findings, feeding 500,000 IU D3/d to finishing pigs improved most Hunter color values at 14 d of storage but did not improve pork-loin chop tenderness at 1 to 21 d of retail shelf storage.

Conjugated linoleic acid (CLA) is a collective term for positional and geometric isomers of linoleic acid. Dietary CLA has been shown to improve feed efficiency, decrease body fat, and increase lean tissue in laboratory animals. We hypothesized that CLA would improve performance and carcass composition and would be deposited in pork tissues. Diets of 40 crossbred pigs were supplemented with CLA to determine its effects on performance and carcass composition. Eight replications of five littermate barrows with an initial average weight of 26.3 kg were allotted at random to individual pens. Within replication dietary treatments containing 0, 0.12, 0.25, 0.5, or 1.0% CLA were assigned at random. Pigs were weighed and feed disappearance was determined at 14-d intervals. Average daily gain increased linearly as the level of CLA increased in the diet (P < 0.05). Average daily feed intake was not affected by the concentration of CLA in the diet. Therefore, a linear increase in gain:feed ratio (P < 0.05) was observed. Carcasses from animals fed control diets had greater 10th rib backfat than carcasses from animals fed CLA (P < 0.05). Ultrasound measurement and carcass measurements showed less fat depth over the loin eye at the 10th rib of pigs fed doses of CLA (P < 0.05) than that observed for control pigs. Belly hardness (firmness) increased linearly as the concentration of CLA in the diet increased when bellies were measured for firmness either lean side up (P < 0.001) or lean side down (P < 0.05). Loin dissection data demonstrated that CLA produced a quadratic treatment effect both for less intermuscular fat (P < 0.001) and less subcutaneous fat (P < 0.05) and a linear increase for bone (P < 0.05), although finished loin weight only tended to increase (P = 0.08). The CLA concentration increased in a linear relationship in both subcutaneous fat (P < 0.001) and lean tissue (P < 0.001). Dietary CLA was incorporated into pig tissues and had positive effects on performance and body composition.

A study involving nine research stations from the NCR-42 Swine Nutrition Committee used a total of 1,978 crossbred pigs to evaluate the effects of dietary ZnO concentrations with or without an antibacterial agent on postweaning pig performance. In Exp. 1, seven stations (IA, MI, MN, MO, NE, ND, and OH) evaluated the efficacy of ZnO when fed to nursery pigs at 0, 500, 1,000, 2,000, or 3,000 mg Zn/kg for a 28-d postweaning period. A randomized complete block experiment was conducted in 24 replicates using a total of 1,060 pigs. Pigs were bled at the 28-d period and plasma was analyzed for Zn and Cu. Because two stations weaned pigs at < 15 d (six replicates) and five stations at > 20 d (18 replicates) of age, the two sets of data were analyzed separately. The early-weaned pig group had greater (P < 0.05) gains, feed intakes, and gain:feed ratios for the 28-d postweaning period as dietary ZnO concentration increased. Later-weaned pigs also had increased (P < 0.01) gains and feed intakes as the dietary ZnO concentration increased. Responses for both weanling pig groups seemed to reach a plateau at 2,000 mg Zn/kg. Plasma Zn concentrations quadratically increased (P < 0.01) and plasma Cu concentrations quadratically decreased (P < 0.01) when ZnO concentrations were > 1,000 mg Zn/kg. Experiment 2 was conducted at seven stations (KY, MI, MO, NE, ND, OH, and OK) and evaluated the efficacy of an antibacterial agent (carbadox) in combination with added ZnO. The experiment was a 2 x 3 factorial arrangement in a randomized complete block design conducted in a total of 20 replicates. Carbadox was added at 0 or 55 mg/kg diet, and ZnO was added at 0, 1,500, or 3,000 mg Zn/ kg. A total of 918 pigs were weaned at an average 19.7 d of age. For the 28-d postweaning period, gains (P < 0.01), feed intakes (P < 0.05), and gain:feed ratios (P < 0.05) increased when dietary ZnO concentrations increased and when carbadox was added. These responses occurred in an additive manner. The results of these studies suggest that supplemental ZnO at 1,500 to 2,000 mg Zn/kg Zn improved postweaning pig performance, and its combination with an antibacterial agent resulted in additional performance improvements.

A cooperative research study was conducted by members of a regional committee (North Central Regional Committee on Swine Nutrition [NCR-42]) to assess the variability in nutrient composition (DM, CP, Ca, P, Se, NDF, and amino acids) of 14 sources of wheat middlings from 13 states (mostly in the Midwest). A second objective was to assess the analytical variability in nutrient assays among 20 laboratories (labs; 14 experiment station labs and six commercial labs). Wheat middlings were obtained from each participating station's feed mill. The bulk density of the middlings ranged from 289 to 365 g/L. The number of labs that analyzed samples were as follows: DM and CP, 20; Ca, 16; P, 15; Se, 7; NDF, 10; and amino acids, 9. Each lab used its own analytical procedures. The middlings averaged 89.6% DM, 16.2% CP, .12% Ca, .97% P, 36.9% NDF, .53 mg/kg Se, .66% lysine, .19% tryptophan, .54% threonine, .25% methionine, .34% cystine, .50% isoleucine, and .73% valine. As expected, there was considerable variation in nutrient composition among the 14 sources (P < .01), especially for Ca (.08 to .30%) and Se (.05 to 1.07 mg/kg). "Heavy" middlings (high bulk density, >335 g/L), having a greater proportion of flour attached to the bran, were lower in CP, lysine, P, and NDF than "light" middlings (<310 g/L), having cleaner bran, resulting in negative correlations between bulk density and CP (r = -.61), lysine (r = -.59), P (r = -.54), and NDF (r = -.81). Each 1-percentage-point increase in CP in the wheat middlings was associated with .0235 (r2 = .61) and 2.1 (r2 = .39)-percentage-point increases in lysine and NDF, respectively. Lysine content was associated with NDF, CP, and bulk density of wheat middlings (r2 = .88). There was considerable variation among laboratories (P < .01) in analysis of all nutrients. The CV among sources (100 x sigmaS/mean) was greater than among labs (100 x sigmaL/mean) for CP, Ca, P, Se, and NDF, but the CV among labs was greater than that among sources for DM and all of the amino acids except lysine and phenylalanine.

An experiment was conducted to determine the effect of high dietary intakes of Zn and Cu and their combination on growth performance of weanling pigs with diverse health status and management strategies. Twelve experiment stations cooperated and used a total of 1,356 pigs that averaged 6.55 kg BW and 22.2 d age at weaning. The four dietary treatments, all of which met or exceeded NRC requirements, were 1) control, 2) 3,000 ppm Zn (from Zn oxide), 3) 250 Cu ppm (from Cu sulfate), or 4) 3,000 ppm Zn and 250 ppm Cu. The diets were fed as a complex Phase I diet (1.4% lysine) for 7 d followed by a Phase II diet (1.2% lysine) for 21 d. Chlortetracycline (220 ppm) was added to all diets. Fecal color (1 = yellow to 5 = black) and consistency (1 = very firm to 5 = very watery) were scored daily for 3 wk. At the end of the 28-d study, 412 pigs were bled at five stations, and plasma Cu, Zn, and Fe concentrations were determined at one station with atomic absorption spectrophotometry. Average daily gain (375, 422, 409, 415 g/d), feed intake (637, 690, 671, 681 g/d), and gain/feed (586, 611, 611, 612 g/kg) were improved (P < .01) by the addition of Zn and(or) Cu. Significant Cu x Zn interactions imply that the responses to Zn and Cu were independent and not additive. There were significant (P < .01) Zn and Cu effects and a Zn x Cu interaction on fecal color (3.17, 3.24, 4.32, 3.57) and consistency (2.39, 2.14, 2.14, 2.13). Dietary additions of Cu and Zn resulted in elevated plasma concentrations of Cu and Zn, respectively. These data indicate that pharmacological additions of 3,000 ppm Zn (oxide) or 250 ppm Cu (sulfate) stimulate growth beyond that derived from intakes of Zn and Cu that meet nutrient requirements. However, the combination of Zn and Cu did not result in an additive growth response.

A cooperative research study involving 635 gilts was conducted at eight research stations to further estimate the lysine requirement of finishing gilts. Dietary crude protein levels of the five dietary treatments ranged from 16.0 to 24.4% with calculated lysine levels of .80, .95, 1.10, 1.25, or 1.40%. Each station contributed a minimum of two replicate pens of pigs per treatment. Average initial and final weights were 53.6 and 116.4 kg, respectively. At the end of the experimental period, pigs were killed and hot carcass weight, 10th-rib fat depth, and longissimus muscle area were measured. Carcass fat-free lean percentage and fat-free lean gain were estimated from these data. Daily lysine intakes averaged 21.8, 25.9, 30.5, 34.3, and 37.8 g/d for the five treatment groups, respectively. Increasing the dietary lysine from .80 to .95% numerically increased weight gain and gain:feed, but these increases were not maintained at higher levels of dietary lysine. Overall, rate and efficiency of gain decreased (cubic, P < .01) with increasing dietary lysine. Carcasses were leaner at the two higher levels of dietary lysine as evidenced by reduced 10th rib backfat (linear, P < .01), increased longissimus area (quadratic, P < .04), and increased percentage of estimated fat-free lean (linear, P < .01). Carcass fat-free lean gain was not influenced by dietary lysine except for a small numerical improvement (P < .11) at the .95% level of dietary lysine that paralleled the improvement in body weight gain. The results indicate that the dietary lysine requirement of finishing gilts with a mean carcass fat-free lean growth rate of 306 g/d from 54 to 116 kg body weight is probably no higher than .80% of the diet to achieve maximum rate and efficiency of body weight gain and carcass lean growth rate. The results also indicate that higher dietary lysine levels may increase carcass leanness in finishing gilts, possibly due to reduced intake of NE. Whether this response is due to the effects of lysine alone, protein (i.e., other amino acids), or soybean meal is unknown.

A cooperative research study involving members of a regional committee (North Central Regional Committee on Swine Nutrition [NCR-42]) was conducted to assess the variability in nutrient composition (DM, CP, Ca, P, Se, and amino acids) of corn and soybean meal from 16 sources (15 states, mostly in the Midwest) and to assess the analytical variability in nutrient assays among 22 laboratories (labs; 16 experiment station labs and six commercial labs). Corn samples were obtained from each participating station's feed mill during a 3-yr period (1989, 1990, and 1992), as were soybean meal samples during a 2-yr period (1989 and 1990). Both regular soybean meal (with hulls) and dehulled soybean meal were represented in the study. Samples were analyzed for DM and CP by all 22 labs, for Ca and P by 15 labs, for amino acids by 10 labs, and for Se by 6 labs. Each lab used its own analytical procedures. Samples of corn and soybean meal varied in their nutrient composition depending on the area of origin. The greatest variation among sources was in Se concentration, ranging from .02 to .29 mg/kg in corn and .08 to .95 mg/kg in soybean meal. Crude protein and lysine in corn were positively correlated, but the regression coefficient was low (r2 = .49). The relationship between CP and lysine for the two soybean meals combined was considerably stronger (r2 = .81). Lysine in corn increased by .018 percentage point and lysine in soybean meal (regular and dehulled combined) increased by .063 percentage point for each 1 percentage point increase in CP. Except for CP and Se, the analytical variability among labs was as great as, and in some cases greater than, the variability in nutrient composition among sources of corn and soybean meal. Within-lab analytical variability tended to be less than among-lab variability. Some labs performed certain analyses with considerably less variability and more accuracy than others.

The effect of dietary amino acid regimen and genetic capacity for lean tissue growth on the lactational performance of sows was determined in primiparous sows with a high (350 to 390 g/d) or low (240 to 280 g/d) genetic capacity for lean tissue growth from 18 to 110 kg of body weight. During lactation, sows were offered daily 6.5 kg of one of four fortified corn-soybean meal diets containing .58, .77, .96, and 1.15% lysine (L). Litters were standardized to 14 pigs within 8 h after birth. On d 2 of lactation, the high lean growth (LG) sows possessed more proteinaceous tissues and protein and less fat tissue and lipid. During lactation (d 2 to 28 postpartum), high LG sows consumed more feed, mobilized more body protein, and lost less body lipid. Milk, milk energy, and milk lysine yields (pooled across dietary regimens) were similar between genotypes. As daily dietary lysine intakes increased from 27 to 62 g and total digestible lysine supplies (from diet and mobilized tissues) increased from 39 to 68 g, daily yields of milk, milk energy, and milk lysine increased, but the magnitude of the response differed (P < .05) between genotypes, evidently because of differences in the ability of the high and low LG sows to mobilize energy from body tissue. Based on these data, the lactational capacities of high and low LG sows nursing 12 to 14 pigs are similar when similar supplies of lysine and energy are available from dietary intake and mobilized body tissue stores. When supplies of ME do not limit milk synthesis, daily digestible lysine intakes of at least 54 g (> or = 66 g from a corn-soy diet) are needed by these sows nursing litters of 12 to 14 pigs to support milk synthesis and minimize maternal protein losses. This is equivalent to a total digestible lysine need of 4.3 to 4.6 g/kg of milk produced. When ME provided by the diet is less than that needed to fuel maximum milk synthesis, however, the dietary amino acid needs of genetically lean sows may be reduced because of their inability to mobilize sufficient body fat stores.

A regional study involving a total of 618 nursery pigs with 468 continuing through the grower-finisher period evaluated the feeding duration of a Phase 1 starter diet (1, 2, or 3 wk) to 23-d old weanling pigs of two weaning weights (5.5 or 7.5 kg). The study was a 3 x 2 factorial arrangement of treatments in a randomized complete block design conducted in 19 replicates during the nursery period, with 14 replicates continuing through the grower-finisher period. Upon completion of feeding the Phase 1 diet for the experimental period, pigs were fed a Phase 2 diet (total of 5 wk for both Phases), whereupon a corn-soybean meal mixture formulated to .80% lysine was fed during the grower (to 56 kg BW) and a .65% lysine diet to a final body weight of 105 kg. Station effects were significant (P < .05) but station x treatment responses were not (P > .15). Pigs with heavier weaning weights gained faster (P < .01) and consumed more feed (P < .01) during each week of the nursery period. Nursery pig gains (P < .06) and gain: feed ratios improved (P < .01) when the Phase 1 diet had been fed for either 2 or 3 wk for both pig weight groups. There was no interaction response during the nursery period between weaning weight or duration of feeding the Phase 1 diet on daily gains or feed intake measurements; however, pigs in the heavier weight group were more efficient (P < .05) in feed utilization when fed the Phase 1 diet for 2 or 3 wk. During the grower-finisher period, gains were higher (P < .01) with the heavier pig group. When the Phase 1 diet had been fed for either 2 or 3 wk to the pigs of either weight group, gains (P < .01) and feed efficiency (P < .05) were improved. There was no evidence of compensatory growth for the lower weight pig group during the subsequent grower or finisher periods. Pigs with heavier weaning weights reached 105 kg BW approximately 8 d sooner (P < .01) and consumed less total feed (P < .05) from weaning to 105 kg than those in the lower weight group. Feeding the Phase 1 diet for 2 wk to pigs of either weight group reduced the time from weaning to 105 kg BW, but weaning heavier pigs seemed to have a greater effect on postweaning performance than the feeding duration of a Phase 1 diet.

Forty-eight barrows (61 kg), 24 Yorkshire x Landrace (YL) and 24 YL x Duroc x Hampshire (YLDH), were used to evaluate the effect of six dietary ME levels on concentrations of plasma urea nitrogen (PUN) and free amino acids. All pigs consumed equal amounts of each nutrient, except for energy. As energy intakes increased from 12.42 to 35.01 MJ/d of ME (34 to 97% of NRC recommendations), ADG increased linearly (P < .001) and concentrations of PUN decreased linearly (P < .01) and quadratically (P < .05). There was a tendency (P = .09) for an interaction of breed combinations and energy intakes on ADG. In general, increasing energy intake decreased plasma concentrations of essential amino acids and increased plasma concentrations of nonessential amino acids. Exceptions were a lack of change in plasma lysine and glutamic acid, an increase in histidine, and decreases in tyrosine and aspartic acid. Concentrations of most plasma amino acids were similar between the two breed combinations, but 9 of 27 amino acids that were measured were different (P < .05) between the breed combinations. The linear response of ADG was probably attained through a relatively constant lean-to-fat deposition ratio in the body over the levels of ME intakes. The curvilinear decline of PUN to increasing energy intakes was probably because at low energy intakes, amino acids were oxidized to furnish energy for maintenance and at increasing energy intakes there was increasing accretion of body proteins.

Two experiments with weanling pigs were conducted to study the effects on growth and immune responses of excess dietary L-leucine (LEU) and dietary supplementation with the LEU catabolites, alpha-ketoisocaproic acid (KIC) and beta-hydroxymethyl butyrate (HMB). In Exp. 1, 80 pigs were randomly allocated according to initial BW and ancestry to five replications of four dietary treatments (four pigs/pen). The control diet contained wheat, oat groats, menhaden fish meal, and dried whey and provided 1.12% LEU. Treatment diets were the control plus 1.12% LEU, 1.12% KIC, or .4% HMB. The experiment lasted 6 wk. In Exp. 2, 36 pigs were randomly allocated to nine replications of four dietary treatments in a 2 x 2 factorial arrangement. Treatments consisted of two concentrations of dietary LEU and a daily i.m. injection of dexamethasone (DEX) or saline. Pigs were fed a control corn-soybean meal and dried whey diet (1.56% LEU) or the control diet plus 1.56% of crystalline LEU. Pigs were individually penned and the experiment lasted 4 wk. Growth performance, plasma free amino acids, plasma urea nitrogen, and humoral and cellular immune responses were measured. Results indicated that LEU concentrations in practical diets and supplementation with KIC and HMB (Exp. 1) did not detrimentally affect growth and immune response. The high LEU concentration and DEX injection used in Exp. 2, however, were detrimental to both growth and immune response.

A repeated-measures experiment was conducted to test the effect of sampling times after feeding on concentrations of plasma urea nitrogen (PUN) and plasma free amino acids (PFAA) in pigs fed by two feeding methods. Seven castrated male pigs (mean weight of 65 kg) were randomly assigned to switchback treatments that were 3-d periods of either free access to feed or twice daily feeding. Blood was sampled at 2-h intervals (sampling points) during the day (0800 to 1800 h) and again during the night (2000 to 0600 h) on the last day of each of three 3-d feeding treatment periods. Concentrations of PUN and most PFAA were not affected by the feeding method and time of day (day and night), but they were affected by sampling points. The pigs fed twice daily had postprandial peak PUN at 4 h (32% increase over prepandial) and peak PFAA at 2 h after feeding during 12-h day and night periods. However, the pigs with free access to feed exhibited only a slight fluctuation of PUN during the day and night and almost constant concentrations of most PFAA during a 24-h period. The PFAA results suggest that concentrations of most plasma essential and nonessential amino acids varied relatively more than those of other amino acids in response to sampling times.

An experiment was conducted to determine the effects of level and chemical form of dietary vitamin E on alpha-tocopherol status of poults. The effects of a dietary bile salt and an antioxidant on concentrations of alpha-tocopherol in serum and liver were also tested. Six dietary treatments were obtained by supplementing a corn-soybean meal diet with 12 IU of DL-alpha-tocopheryl acetate (TA)/kg (LE), 12 IU of TA plus 800 mg of sodium taurocholate/kg (LB), 12 IU of TA plus 500 mg of ethoxyquin/kg (LS), 12 IU of D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS)/kg (LT), 100 IU of TA/kg (HE), and 100 IU of TPGS/kg (HT). Growth rate and feed efficiency of poults were unaffected (P > .05) by dietary treatments. The HE diet increased alpha-tocopherol in liver (P < .01) at 14 and 21 days of age. Liver and serum alpha-tocopherol concentrations were unaffected by dietary TPGS (LT and HT diets) at any age. Serum alpha-tocopherol concentration was unaffected by dietary treatments at 5 days of age. The HE diet, however, increased (P < .01) serum alpha-tocopherol at 9, 14, and 21 days of age. Age-related changes in alpha-tocopherol concentration were observed. Both liver and serum alpha-tocopherol decreased markedly from 1 to 14 days of age. The HE diet only partly alleviated the reduction of alpha-tocopherol in liver and serum. The water-soluble form of vitamin E, TPGS, dietary sodium taurocholate, or dietary ethoxyquin, did not prevent the marked decline in alpha-tocopherol concentration of liver and serum during the 21-day experiment.

A cooperative research study involving three experiments and 2,318 pigs was conducted at 12 research stations to evaluate the protein (lysine) requirements of barrows and gilts. The two sexes were penned separately and fed fortified corn-soybean meal diets containing protein levels ranging from 12.0 to 17.2%. Lysine levels in these diets ranged from .52 to .90%. Protein levels in Exp. 1 were 12, 14, and 16%; in Exp. 2, protein levels were 13, 14, 15, and 16%; and in Exp. 3, they were 13.2 15.2, and 17.2%. Fat (5%) was added to one-half of the diets in Exp. 3. Each station that participated contributed a minimum of two replicate pens of pigs per diet-sex combination in a given experiment. Average initial and final weights were 35 and 99 kg in Exp. 1 and 51 and 105 kg in Exp. 2 and 3, respectively. At the end of the test period, pigs were slaughtered and hot carcass weight, 10th rib fat depth, and longissimus muscle area were measured. Percentage of carcass muscle was estimated from these data. Overall, barrows gained weight faster than gilts (P < .01), but gilts required less feed per unit of gain (P < .05) and had less backfat, larger longissimus muscle areas, and a greater percentage of carcass muscle (P < .01) than did barrows. Lean growth rate was similar for barrows and gilts (332 vs 329 g/d). Increasing the dietary protein or lysine level resulted in improved rate and efficiency of gain and increased carcass leanness and lean growth rate in gilts, but the increase was less pronounced or did not occur in barrows, resulting in protein level x sex interactions. Feeding low-protein (12 or 13%) diets decreased performance and carcass leanness to a greater extent in gilts than in barrows. The pooled data from the three experiments indicated that most traits tended to reach a plateau at 13% CP (.60% lysine) in barrows, whereas in gilts, weight gains, feed/gain, carcass muscle, and lean growth rate continued to improve, but at a decreasing rate, with up to 17.2% CP (.90% lysine). The results indicate that gilts require higher concentrations of dietary amino acids to maximize lean growth rate than do barrows.

A 13-wk trial was conducted with 32 pigs to determine the effects of dietary Cu (250 ppm) and alpha-tocopheryl acetate (ATA, 22 IU/kg) on the performance, serum enzymes, serum and tissue tocopherols, and antibody production in growing pigs. Pigs were fed corn-soybean meal diets containing 21% CP the first 4 wk and 18% CP during the rest of the trial. All feed was stored a minimum of 14 d before it was fed. The addition of Cu decreased (P less than .01) the concentration of alpha-tocopherol in the feed. alpha-Tocopherol concentrations were less than .01 mg/kg in the starter diet and less than 2 mg/kg in the grower diet after 14 d of storage. Supplemental Cu or ATA had no effect on ADG, feed intake, or gain:feed during the first 4 wk. During wk 5 to 13, the addition of Cu to diets containing no ATA increased daily feed intake and decreased gain:feed, but with ATA addition, feed intake decreased and gain:feed increased, resulting in a Cu x ATA interaction (P less than .05). The addition of Cu or ATA had no effect (P greater than .1) on serum glutathione peroxidase or lactic dehydrogenase activity. Serum tocopherols were reduced (P less than .05) by the addition of Cu during wk 1 to 4, 6 (P less than .01), and 7 (P less than .05) and increased (P less than .01) by ATA addition during the entire experiment. The addition of ATA increased the tocopherol concentrations in bile, ham, heart, pancreas, kidney, spleen, liver, psoas and longissimus muscle (P less than .01), kidney fat, backfat, and adrenal gland (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

The stability of alpha-tocopheryl acetate and inherent tocopherols in swine grower diets containing high levels of trace minerals was studied in a 12-wk experiment. Corn-soybean meal diets with either 0 or 1% crude soybean oil and without trace minerals added (NOTM) were supplemented with a standard trace mineral mix (TM), TM + 250 ppm of Cu, TM + 1,000 ppm of Fe, TM + 1,000 ppm of Zn, or TM + 100 ppm of Mn. Alpha-tocopheryl acetate decreased linearly (P less than .0001) during 12 wk of storage in diets containing NOTM, TM, Zn, or Mn at a rate of .015 mg/d. Addition of Fe (P less than .005) or Cu (P less than .05) increased the rate of alpha-tocopheryl acetate loss. The addition of soybean oil had no effect (P greater than .1) on the rate of alpha-tocopheryl acetate loss. The alpha-tocopherol levels of the NOTM diet decreased (P less than .01) by approximately 50% during the 12-wk storage period. Addition of TM alone in diets that did not contain soybean oil had no effect P greater than .1) on the rate of alpha-tocopherol loss. The addition of Cu, Fe, Zn, or Mn (P less than .05) to diets that did not contain soybean oil increased the rate of alpha-tocopherol loss in comparison with NOTM and TM diets. Addition of Cu decreased alpha-tocopherol below 10% of initial levels in approximately 10 d. The addition of soybean oil to the diets containing TM, Fe, Zn (P less than .005), or Mn (P less than .05) further increased the rate of alpha-tocopherol loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Two trials were conducted to evaluate the effect of dietary replacement of .30% sodium chloride (NaCl) with a sodium-equivalent amount of sodium bicarbonate (NaHCO3) on leg weakness in swine. Three lines of Duroc swine established by six generations of divergent selection for front leg structure were used. In the first trial, a total of 80 low-line (increased leg weakness), 75 high-line (decreased leg weakness), 80 control-line (intermediate leg weakness) and 80 high x low pigs were used. Pigs were assigned within litter to an experimental or control diet and tested from approximately 37 to 104 kg live weight. The experimental diet contained .43% NaHCO3, replacing .30% NaCl in the control diet. Pigs had ad libitum access to feed. In the second trial, 48 high- and 48 low-line pigs were fed the same diets from 29 to 104 kg. At the completion of each trial, pigs were scored for various leg traits. The model used for statistical analyses included the effects of replicate, genetic line, dietary treatment and the dietary treatment x genetic line interaction. Trials were analyzed separately. Results indicated that there was no significant improvement in clinical signs of leg weakness due to dietary supplementation with NaHCO3 for front leg structure and movement, rear leg movement or rear toe size. Rear hock angle was improved in Trial 1 (P less than .05) but was reduced in Trial 2 (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)

Two experiments were conducted to evaluate the effect of the addition of high levels of Cu (as CuSO4), Fe (as FeSO4) or Zn (as ZnO) to swine starter and grower diets on performance and vitamin E and Se status. The stability of natural tocopherols in mixed feeds was evaluated during storage. Addition of 1,000 ppm Fe or 1,000 ppm Zn had no effect on rate or efficiency of weight gain in either experiment. In Exp. 1, the addition of 250 ppm Cu improved daily gain and efficiency of feed utilization (P less than .05) during the first 3 wk of the experiment. Copper had no effect on pig performance during the rest of Exp. 1 or in Exp. 2. Serum lactate dehydrogenase or glutathione peroxidase activity was not affected (P greater than .1) by any of the mineral additions. Serum tocopherols were not affected by the mineral treatments in Exp. 1. In Exp. 2, addition of 250 ppm Cu decreased (P less than .01) serum tocopherol levels throughout the 8-wk experiment. The alpha-tocopherol levels of the starter diet decreased (P less than .05) during storage. Addition of 250 ppm Cu (P less than .01) or 1,000 ppm Fe (P less than .05) or 1,000 ppm Zn (P less than .05) increased the destruction of alpha-tocopherol in the starter diet. Alpha- and gamma-tocopherol levels of the starter diet decreased to near zero in 22 d in the presence of 250 ppm Cu. In the grower diet, the addition of 250 ppm Cu (P less than .01) or 1,000 ppm Fe (P less than .05) increased the destruction of tocopherols.(ABSTRACT TRUNCATED AT 250 WORDS)

Pigs from sows fed a diet deficient in Se and low in vitamin E were fed a Torula yeast diet supplemented with 100 IU dl-alpha-tocopheryl acetate/kg of diet. Dietary treatments were levels of supplemental Se of 0, .025, .050, .075 or .100 ppm. Some death loss occurred in pigs receiving no supplemental Se at approximately 5 wk of age. Autopsy revealed liver and heart lesions typical of vitamin E-Se deficiency. Selenium supplement had no significant effect on average daily gain, feed intake or gain to feed ratio for the 4-wk experiment. Selenium status of pigs was determined by serum Se concentration and serum glutathione peroxidase (GSH-Px) activity. Serum Se increased linearly (P less than .01) with increasing supplemental Se. Serum GSH-Px activity increased linearly (P less than .01) and quadratically (P less than .05) with increasing supplemental Se. With time, the level of serum Se and GSH-Px activity decreased in unsupplemental pigs, but increased in pigs fed diets supplemented with Se and resulted in significant interactions (P less than .01) between dietary Se level and time on experiment. The correlation between serum Se concentration and GSH-Px activity was .81 (P less than .01).

The influence of dietary glucose (G) and sucrose (S) on leucine metabolism was evaluated in 10 immature pigs. The diets were isoenergetic and isonitrogenous with 40% of energy being derived from G or S. Animals were fed their diets at least 1 wk prior to the study. Each animal was studied by using a continuous infusion of L-[4,5-3H]leucine and [U-14C] alpha-ketoisocaproate (KIC) to permit measurement of the metabolism of leucine. After a meal, the pigs fed the glucose meal had higher mean plasma glucose and insulin concentrations than pigs fed a sucrose-containing meal. Arterial KIC concentration decreased after feeding either meal, but the arterial leucine concentration remained unchanged. In pigs fed sucrose, plasma fructose increased after the meal and was cleared by the hind limb in the same proportion as plasma glucose (11%). The hind limb glucose clearance was 16% in the glucose-fed pigs. Animals fed the glucose meal had three times greater hind limb uptake of leucine than animals fed the sucrose meal. No dietary influence on hind limb metabolism of KIC could be detected from arterial-venous differences. The whole-body leucine-KIC kinetic data suggested that preprandial tissue proteolysis was greater in pigs fed glucose than in those fed sucrose. Postprandial protein synthesis increased (24%) over fasting values only in pigs fed glucose. This was accompanied by a decrease in the percentage of the leucine pool converted to KIC. These observations indicate that both pre- and postprandial aspects of protein metabolism can be influenced by the dietary carbohydrate source.

The effect of dietary selenium on the subcellular distribution of selenium-dependent glutathione peroxidase (SeGSH-Px) activity in rat liver, epididymal fat pad, and seminal vesicle was determined. Tissues were fractionated by differential centrifugation, and the subcellular distribution of SeGSH-Px activity was determined by comparison with the distribution of biochemical marker enzymes. Liver SeGSH-Px activity was located in both the cytosol and mitochondria. In epididymal fat pad and seminal vesicle, SeGSH-Px activity was located primarily in the cytosol; association with another subcellular organelle, however, was indicated. In liver and epididymal fat pad, SeGSH-Px activity increased linearly, and, in the seminal vesicle, increased linearly and quadratically, with increasing dietary selenium concentration. Distribution of SeGSH-Px activity among the cellular fractions from the tissues, however, was not affected by dietary selenium supplementation.

The effect of Se deficiency on pancreatic digestive enzyme activity and nutrient digestibility was studied by using pigs weaned at 3 wk of age from sows fed a diet deficient in Se and low in vitamin E. Pigs were fed a Torula yeast diet supplemented with 100 IU dl-alpha-tocopheryl acetate/kg of diet. Treatments were levels of supplemental Se of 0, .025, .050, .075 or .100 ppm. Apparent digestibility was determined at the end of the second and fourth week. Digestive enzyme activity, glutathione peroxidase (GSH-Px) activity and Se concentration were determined in pancreatic tissue at the end of the 4-wk experiment. Selenium concentration in the pancreas increased linearly (P less than .01) and quadratically (P less than .05) in response to increasing level of Se supplementation. The correlation between pancreas Se level and GSH-Px activity was .36 (P less than .05). Supplementation of Se had no effect on pancreas weight, protein content or the activity of pancreatic trypsin, chymotrypsin, alpha-amylase or lipase. Apparent digestibility increased linearly for dry matter (P less than .01) and N (P less than .05) as Se supplementation increased. There was however, no significant effect on ether extract digestibility. Apparent digestibilities were higher (P less than .01) at 4 wk than those measured at 2 wk.

Female rats were fed a selenium-deficient diet composed of Torula yeast, sucrose, vitamins (including tocopheryl acetate) and minerals from weaning and during breeding, gestation and lactation. The offspring were used to study the effects of selenium on growth, diet utilization and growth hormon status. The Torula yeast diet containing 200 IU dl-alpha-tocopheryl acetate was fed alone or supplemented with 0.025 or 0.1 ppm of selenium as selenite. Rats fed the selenium-supplemented diets grew significently faster and consumed significantly more diet than rats fed the unsupplemented diet. Anterior pituitary weights were lower in selenium-deficient rats, but if expressed per unit of body weight, were similar to pituitary weight of selenium-supplemented animals. Total growth hormone in the anterior pituitary was reduced in selenium-deficient rats. A metabolism study indicated that rats allowed ad libitum access to supplemented diets consumed more diet and obtained more metabolizable energy from the diet than rats fed the deficient diet. It the intake of rats fed the supplemented diets was limited to that of rats allowed ad libitum access to deficient diet, growth of rats was similar. However, metabolizable energy content of the diet increased quadratically and nitrogen digestibility increased linearly as thelevel of selenium increased. Selenium deficiency reduced growth primarily by decreased diet consumption, but also reduced the utilization of energy and nitrogen.

Effects of intramuscular injections of selenium and vitamin E on lesions in pigs with selenium-vitamin E deficiency syndrome were determined in 2 factorial experiments, using a total 69 pigs. The pigs were fed a selenium-vitamin E deficient, 22.3% protein ration, supplemented with methionine, minerals, and vitamins. Weekly intramuscular injections of isotonic saline solution, vitamin E, selenium, or vitamin E and selenium were given to the respective treatment groups. Selenium-vitamin E deficiency lesions occurred only in pigs that were given saline injections. Weekly intramuscular injections of either selenium (as selenous acid buffered to pH (7.3) at the rate of 0.05 mg/kg of body weight or vitamin E at the rate of 20 IU/kg of body weight or the combination of selenium and vitamin E prevented cardiac and skeletal myodegeneration, hepatic necrosis, and death. Significant increases of serum aspartate aminotransferase activity values were noted in pigs with liver, heart, or skeletal muscle lesions, but these increases were not correlated with the extent of the lesions. Vascular lesions, epicardial and endocardial hemorrhages, and yellow discoloration of body fat were not features of this experimentally induced disease. These lesions may be related to factors other than the deficiency of selenium, vitamin E, or selenium and vitamin E in rations previously used in reported studies.