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Ninety-six crossbred young pigs (body weight 7.8 kg) were used in a 5-week trial to determine the effectiveness of microbial phytase (EC3.1.3.26) in improving the bioavailabilities of P and other nutrients in maize–soyabean-meal diets and, thus, replacing inorganic P with phytase. A 2 x 5 factorial arrangement of treatments was employed with two available P (aP) levels (0.7 and 1.6 g/kg) and five phytase levels (0, 350, 700, 1050, 1400 U (the quantity of enzyme that liberates 1µmol inorganic phosphate/min from 5.1 mm-sodium phytate at pH 5.5 and 37°)/kg diet). In addition, two extra diets were formulated to supply the National Research Council (1988) recommended level of aP (3.2 g/kg) with 0 or 1400 U phytase. The addition of graded levels of phytase resulted in linear increases in average daily weight gain, average daily feed intake and weight gain:feed intake for pigs fed on diets containing 0.7 or 1.6 g aP/kg (P < 0.04). Also, the addition of phytase linearly increased apparent digestibilities of P and Ca (P < 0.01), whereas faecal P excretion was linearly decreased (P < 0.01). Linear increases in shear force, shear energy and ash content of both the metacarpal and tenth rib, and shear stress of the metacarpal were found to respond to added phytase (P < 0.01). These improvements in performance, apparent P absorption and bone measurements by phytase were also observed by increasing dietary aP levels for most measurements. Adding 1400 U phytase to the 3.2 g aP/kg diet further increased average daily weight gain, average daily feed intake, apparent absorption of P, Ca and N and metatarsal shear force and ash content (P < 0.01 to 0.05). Generally, maximum responses occurred at a phytase level of 1050 U/kg diet for the 0.7 g aP/kg diets and 700 U for the 1.6 g aP/kg diets. Based on non-linear and linear response equations generated for the phytase and aP levels, the average function of the equivalency of P (Y, g/kg) v. microbial phytase (X, U/kg) was developed across aP levels of 0.7 and 1.6 g/kg for average daily weight gain and apparent digestibility of P: Y = 2.622–2.559e-0.00185x. The replacement of 1 g inorganic P as defluorinated phosphate would require about 246 U microbial phytase. This represents 41% of released P from phytate.

Tibial traits were investigated for turkey poults fed on soyabean-meal-based semi-purified diets high in phytate P (2·2 g/kg) with added phytase and inorganic P. Dietary treatments were: (1) 2·7 g non-phytate P (nP)/kg; (2) diet 1 + 1000 U phytase/kg diet; (3) 36 g nP/kg; (4) diet 3+800 U phytase; (5) 4·5 g nP/kg; (6) diet 5+600 U phytase; (7) 6·0 g nP/kg. Added phytase and nP increased (P< 0·006) tibial dry matter, ash weight and content, body-weight gain, feed intake and gain:feed. The Mg and Zn concentrations in the tibial ash were also increased (P< 0·001 andP< 0·09 respectively) by added phytase or nP; tibial P and Ca concentrations tended to be increased. Hypertrophy zone width of the tibial proximal end decreased (P< 0·001), while proliferating zone width, tibial length, and widths at the long and short axes increased (P< 0·003) as phytase and nP were added. The addition of phytase also tended to enlarge the cartilaginous zone width, which was linearly increased (P< 0·05) by added nP. Disorganization scores of the hypertrophy zone and trabecular bone were low, approaching normal (P< 0·05), for turkey poults fed on diets with phytase supplementation, and tibial abnormality scores were linearly decreased (P< 0·001) as nP levels increased (zero score is considered normal). Adding phytase and nP improved the orderliness of development, mineralization and arrangement of cartilage and bone cells, and alleviated the effects of P deficiency on the histological and gross structure of the tibias. Tibial shear stress increased (P< 0·04) as phytase and nP were added. In summary, similar improvements in bone characteristics were achieved for turkey poults fed on a P-deficient diet supplemented with either phytase or nP.

Male 1-d-old broilers (n 920) were given 0, 200, 400, 600, 800, 1000 and 1200 U microbial pbytase/kg diet in combination with 2·0, 2·7 or 3·4 g non-phytate P (nP)/kg or 4·0, 5·1 or 5·8 g total P (tP)/kg in a 21 d trial to assess the effectiveness of phytase in a maize–soyabean-meal diet. In addition to the above twenty-one diets, a positive control P diet supplied 4·5 g nP/kg, 6·9 g tP/kg and 10 g Ca/kg. The basal diet contained 230g crude protein/kg, 8·8 g Ca/kg, 4·4 g tP/Fg and 2/0 g nP/kg. Defluorinated phosphate and limestone were used to supply P and Ca. A Ca:tP ratio of 2:l was maintained except in the positive control diet which had a ratio of 1·45: 1. Phytase additions linearly increased (P < 0·01) body-weight (SW) gain, feed intake, toe ash percentage, and apparent retention (% of intake) or total amount (g/bird) of retained Ca and P, and linearly decreased (P < 0·01) P excretion (g/kg of DM intake) at each level of nP with the magnitude of the response inversely related to the level of nP. Above-normal mortality was only observed in the group receiving 2·0 g nP/kg diet without phytase. Adding nP linearly increased (P < 0·01) BW gain, feed intake, toe ash percentage, Ca retention, total amount (g/bird) of P retained, and P excretion, and iinearly decreased (P < 0·01) apparent retention (%) of P. Derived linear and non-linear equations for BW gain and toe ash percentage at the two lower nP levels, 2·0 and 2·7 g/kg, were used to calculate P equivalency value of microbial phytase. The results show that 939 U microbial phytase is equivalent to 1 g P from defluorinated phosphate in broilers fed on maize–soyabean-meal diets. The amount of P released per 100 U phytase decreased as the total amount of phytase increased.

Eighty-six crossbred (Duroc x Yorkshire) gilts were used in two trials to assess the effect of supplemental dietary fats during early gestation on fetal survival, fetal development, and fatty acid (FA) composition in gilt plasma and fetal head and body at d 37 to 45 after breeding. Three diets contained 4% (wt/wt) added fat either as coconut, soybean (SO), or menhaden oils (MO). A fourth diet containing corn starch approximately isoenergetic to the quantity of the oils was used as a control. Across both trials, fetal survival percentage did not differ (P.10) according to treatment, but in Trial 2 fetal survival was higher (P.06) for gilts fed the MO diet than for gilts fed the control diet. The FA composition of plasma of gilts at slaughter and the conceptus tissues were similar; both were influenced by the FA composition of the diets. The ratio of n-3:n-6 FA was higher in conceptus tissue than in maternal plasma and the ratio was higher (P.05) for the MO diet than for the other diets. Subsequently, a total of 46 multiparous females were used in three trials to further evaluate the effects of MO on percentage of fetal survival relative to the corn starch control diet; the results demonstrated no differences (P.10) in percentage of fetal survival due to the addition of MO. The high percentage of fetal survival observed in gilts on all the treatments and the unequal ovulation rate in sows on different oil diets precluded definitive conclusions regarding the effects of supplemental oil on fetal survival.(ABSTRACT TRUNCATED AT 250 WORDS)

A cooperative regional study involving 850 litters was conducted at five experiment stations (Arizona, Florida, Oklahoma, Texas, and Virginia) to assess the effects of feeding 220 mg/kg of chlortetracycline (CTC) from 1 wk before to the initiation of the breeding season to 15 d after the breeding season and(or) from 110 d of gestation through lactation on reproductive performance of sows (2 x 2 factorial). Sows were fed 1.82 kg/d (2.27 kg during December, January, and February) during the breeding period and before farrowing. Feed was consumed on an ad libitum basis during lactation. Feeding CTC during the breeding season increased litter size at birth (10.8 vs 10.3; P < .05) and decreased feed consumption (5.4 vs 5.5 kg/d; P < .05) in the subsequent lactation period. Feeding CTC during lactation reduced lactation weight loss in sows (4.3 vs 6.1 kg; P < .07). Feeding the antibiotic at breeding had no effect on conception rate; however, feeding the antibiotic during lactation improved subsequent conception rate at the first service (80 vs 73%; P < .10) and overall conception rate (89 vs 84%; P < .05). This indicates that some carryover effect of feeding CTC during lactation occurred during the subsequent breeding period. Station x treatment interactions were observed for survival rate to 21 d (P < .05) and to weaning (P < .06). Overall, survival rates were not greatly affected by antibiotic feeding. No treatment interaction was observed for any trait measured, indicating that the effects of CTC during the breeding and lactation periods were independent.(ABSTRACT TRUNCATED AT 250 WORDS)

Two experiments were conducted to study the role of feed intake and feed efficiency in Cu-stimulated growth of weanling pigs. In Exp. 1, 42 pigs were randomly assigned into three treatments: 1) control: ad libitum access to a corn-soybean meal-dried whey basal diet; 2) ad libitum/Cu: ad libitum access to the basal diet supplemented with 215 ppm of Cu; or 3) pair-fed/Cu: pair-fed the Cu-supplemented diet to the level of the control. Over the 14-d experiment, the ad libitum/Cu pigs had greater (P < .05) ADG and ADFI than the control pigs. The pair-fed/Cu group had an intermediate ADG. Gain:feed (GF) was not significantly affected by treatments but tended to be improved in the pair-fed/Cu pigs. Feeding copper increased (P < .05) the concentration of Cu in the serum, liver, and brain. Also, feeding Cu increased (P < .05) serum mitogenic activity and growth hormone mRNA concentrations for both feeding methods. In Exp. 2, a 2 x 2 x 2 factorial arrangement of treatments with two levels of Cu (15 vs 200 ppm), two levels of feeding (ad libitum vs restricted [85% of the ad libitum]), and two sources of Cu (Cu sulfate vs Cu lysine) was used in a 24-d experiment involving 96 pigs. Feeding copper increased (P < .05) ADG and GF. The magnitude of the Cu-stimulated growth was reduced by restricted feeding (Cu level x feeding level interaction; P < .05). The ADFI was greater (P < .05) for the pigs fed high dietary Cu only during d 1 to 6. Pigs fed Cu lysine had greater ADG and ADFI than those fed Cu sulfate (P < .05); the benefit in ADG from Cu lysine was reduced by restricted feeding (Cu source x feeding level interaction, P < .05). High dietary Cu stimulated (P < .05) serum mitogenic activity; the stimulation was greater for Cu lysine than for Cu sulfate. Feeding Cu numerically increased GH mRNA concentration. Restricted feeding reduced overall serum mitogenic activity (P < .05), but the response to high dietary Cu and Cu lysine was still evident. In summary, Cu-stimulated growth was largely dependent on a simultaneous increase in feed intake, but there were some improvements in GF. The influence of Cu on serum mitogenic activity was independent of feed intake or growth in both experiments, which indicates a direct action of Cu on the growth regulatory system.

Crossbred female swine (n = 393) were used in a multiparity study at five experiment stations to evaluate the effects of dietary supplementation of folic acid (FA) on serum folates status and reproductive performance. The dietary treatments were a corn-soybean meal basal diet (calculated FA, .34 ppm) supplemented with 0, 1, 2, or 4 ppm FA. Experimental diets were fed continuously from a minimum of 21 d before first mating throughout the entire study. At one station, blood samples for radioimmunoassay determination of serum folates concentration were collected by vena cava puncture at mating, d 55 of gestation, d 110 of gestation, and at weaning. Stage of reproduction and dietary FA supplementation affected (P .10) by inclusion of FA in the diet. The number of days postweaning to estrus also was not affected by FA treatment. Under the conditions of this experiment, increasing level of FA in the diet had a pronounced effect in attenuating decreased serum folates concentration during gestation but was without benefit to reproductive performance.

This study was conducted to examine whether Cu could exert its growth-promoting effect when injected, rather than being fed, and thus bypass the gastrointestinal tract. In two 18-d experiments, pigs were injected every 2 d with a Cu histidinate or histidine solution. Amounts of Cu injected were calculated to simulate varying absorption rates in pigs fed 250 ppm of dietary Cu. In Exp. 1, 44 pigs were randomly assigned to four groups of 11 pigs each. Pigs were injected with four levels of Cu histidinate (0, 5, 10, and 15% estimated apparent absorption coefficients based on calculated feed intake). Average daily gain responded quadratically (P < .05) to levels of Cu histidinate; maximum growth was seen in the 5% group. At d 6, serum mitogenic activity also exhibited a similar quadratic response (P < .05). In Exp. 2, estimated Cu absorptions of 0, 2, 4, 6, and 8% were tested. Forty-five pigs were randomly assigned to five groups of nine pigs each and injected as in Exp. 1. Both ADG and serum mitogenic activity displayed a quadratic response (P < .05); the maximum response was seen in the 4% group. Liver Cu content, superoxide dismutase activity, and serum Cu concentrations were linearly increased (P < .05) with increasing dosage of Cu in both Exp. 1 and 2. Also, brain Cu content linearly increased (P < .05) with increasing dosage of Cu in both Exp. 1 and 2. Also, brain Cu hormone mRNA concentrations in Exp. 2 were not significantly influenced by treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Crossbred weanling pigs (n = 96, average initial weight, 8.4 kg) were used in a 6-wk trial using a 2 x 2 x 3 factorial arrangement of treatments to determine the effects of floor space allowance (.28 and .14 m2/pig), dietary Se (40 and 200 ppb), and dietary Zn (30, 80, and 250 ppm) on growth performance, clinical pathology measurements, serum minerals, and enzymes, liver enzymes, and adrenal weights. Pigs (four/pen) were given ad libitum access to feed and water. Body weight and feed consumed were recorded weekly, and heparinized blood samples were taken for the various assays. Three pigs per pen were killed at the end of the trial for gross examination of organs and tissues and for liver enzymes assays. Pigs housed with restricted floor space ate 21% less (P < .001) and grew 18% more slowly (P < .001) than pigs housed with adequate floor space, but their gain:feed ratio was 4% higher (P < .08). Growth performance was not influenced by dietary Se and Zn treatments. There was no mortality in any of the treatments, and no visible gross abnormalities in organs and tissues at necropsy examination, except that more musculoskeletal bruising was observed for pigs housed with adequate floor space. This finding is supported by higher serum K concentration and creatine phosphokinase activity for pigs housed with adequate floor space. Corticosteroid activity and adrenal weights were similar for all treatments. Concentrations of blood Se and glutathione peroxidase were positively related to dietary Se levels, and serum Zn concentration was related to dietary Zn levels. Other effects of dietary Se and Zn on clinical pathology measurements were minimal and usually unexplained. Most two-way interactions of Se and Zn with floor space allowance were nonsignificant, which suggests that the main effects of Se, Zn and floor space were independent. Some hematologic values, serum metabolites, serum minerals, and serum and liver enzymes were decreased or increased, which is suggestive of stress of pigs housed with restricted floor space. However, most values were unchanged, and a few changed in the direction to suggest benefits of restricting space; all values were within an expected normal range.

Four trials using 312 weanling pigs (average initial weight, 7.2 kg) were conducted to examine the effect of Bifidobacterium globosum A (BGA) on the growth performance, scour scores, humoral and cell-mediated immune response, and pH and chloride ion concentration (CIC) of feces and gastrointestinal tract contents of pigs. Dietary treatments were 0, 5.0 x 10(4), 6.7 x 10(6), and 7.5 x 10(8) colony forming units (cfu) of BGA/d in Trial 1 and 0, 6.0 x 10(4), 5.0 x 10(5), and 5.0 x 10(6) cfu/d in Trials 2 through 4. Pigs fed the low or medium levels of supplemental BGA had a greater ADG (P < .05) than control pigs throughout Trial 1, whereas ADG was quadratically increased (P < .05) for the low or medium levels only during wk 3 to 5 for the pooled data for Trials 2, 3, and 4. The primary effect of dietary BGA additions on ADFI was a quadratic increase during wk 3 to 5 for Trial 1 (P < .05) and for the pooled data of Trials 2 through 4 (P < .10). Gain:feed ratios were generally unaffected by addition of BGA. Both ADFI and ADG tended to be decreased (P < .10) at the highest level of BGA in all trials. Scouring was not severe in any of the trials and was not consistently affected by feeding BGA. The pH and CIC of gastrointestinal contents or feces were not influenced by the feeding of BGA.(ABSTRACT TRUNCATED AT 250 WORDS)

Ninety-six crossbred weanling pigs (36 d of age, initial weight of 8.8 kg) were used in a three-phase study to determine the effects of feeding an aflatoxin-contaminated corn (AC) diet (922 ppb of aflatoxin B1) with and without sodium bentonite (clay) on performance, liver function, and mineral metabolism. In the nursery phase, control corn (NC) or AC was fed in corn-soybean meal diets with and without 1% clay for 6 wk. Compared with NC, AC decreased ADFI and ADG (P < .01) and increased serum activities of gamma-glutamyltransferase (P < .01) and alkaline phosphatase (P < .05). In the growing phase, 48 pigs from the nursery phase were fed NC but continued on their respective clay treatments for 5 wk. Pigs previously fed AC had higher (P < .01) ADFI and lower (P < .05) gain/feed, serum Ca, K, and glucose; ADG, other serum values, and liver minerals were not affected by treatments. In the metabolism phase, 24 barrows from the nursery phase were continued on the same corn and clay treatments for two 4-d total collections of urine and feces. Feeding AC increased (P < .05) P and Na absorption. The addition of clay lowered Mg and Na absorption (P < .01) for both AC and NC. Significant interactions for many minerals indicated that the effects on mineral metabolism were more pronounced when AC was fed. Serum and liver mineral concentrations were generally unaffected by the treatments in all phases. Feeding clay with AC results in partial restoration of performance and liver function without greatly influencing mineral metabolism.

Three 35-d trials involving 288 crossbred weanling pigs (initial weight, 7.1 kg; age, 28 d) were used to determine the separate and interactive effects of two floor space allowances (.28 and .14 m2/pig) and three dietary lysine levels (NRC recommended, NRC+ .1% crystalline lysine-HCl, and NRC+ .2% crystalline lysine-HCl) on growth performance and several factors that measure variation within pens. Each trial was conducted as a 2 x 3 factorial arrangement of treatments in a randomized complete block design. There were four pens (four pigs per pen) for each of the six treatment combinations in each trial. The lysine x floor space allowance interaction was not significant (P = .25) for daily gain, daily feed intake, or gain/feed. Restriction of the floor space allowance decreased (P < .001) daily gain and daily feed intake, but gain/feed was not affected. The humoral immune response, as measured by the level of antibodies produced after two injections of ovalbumin, was not affected by floor space allowance. Addition of .1 and .2% crystalline lysine-HCl improved daily gain (P < .07), gain/feed (P < .10), and humoral immune response (P < .05) and was without effect (P = .28) on feed intake. Natural logarithms of variance, coefficients of variation, and range of daily gain and body weights were not changed by floor space allowance or dietary lysine level. Pigs on adequate and restricted floor space allowances responded similarly to dietary lysine levels.(ABSTRACT TRUNCATED AT 250 WORDS)

The potential of diet acidification to overcome the digestive insufficiency and postweaning lag in early weaned pigs is examined in the review. A survey of published data on various types of acidifiers reveal considerable variation in response to acidification of weaner diets. Several reasons may be proposed to explain the inconsistencies in response, these include differences in diet type, age of pigs, type and level of acidifier, and existing performance levels. Reducing the gastric pH does not appear to be the primary effect of acidifiers. Acidification, however, consistently suppressed pathogenic coliforms in the gastrointestinal tract. Future developments in the use of acidifiers would be intrinsically linked to the understanding of their mode(s) of action in the animal.

In two herds that used different breeding and housing schemes, altrenogest (15 mg/d) was fed for 14 d to gilts or 10 d to sows in .45 kg of a diet formulated to meet or exceed their nutrient requirements. In Herd 1 (five breeding seasons per year), 63 of 123 gilts and 40 of 70 sows in seven replications were fed in individual crates to ensure proper intake. In Herd 2 (continuous breeding), 244 of 484 gilts in 20 replications received the treated feed in individual feeding stalls to which animals had free access. Average and median days to estrus were reduced (P less than .01) for treated gilts and sows compared with controls in both herds. Of 29 treated gilts that did not mate or become pregnant, three had cystic follicles, compared to 1 of 14 controls. There were no statistically significant treatment differences in litter size born or number of stillborn pigs in either herd, but farrowing rates of cycling gilts were 8% lower (P less than .05) in Herd 2 for treated gilts than for controls. Overall, altrenogest could be a valuable tool for improving reproductive efficiency by allowing producers to better control the estrous cycle.

Weanling pigs (n = 176), 21 to 26 d of age (average initial weight, 7.1 kg), were used to evaluate the effects of weaning time (evening vs morning) and feeding time (immediate vs delayed) on postweaning performance. Pigs were randomly allotted within litters to four treatments in a 2 x 2 factorial arrangement as follows: 1) weaning at 2000 with immediate feeding, 2) weaning at 2000 with 12-h delayed feeding, 3) weaning at 0800 with immediate feeding, and 4) weaning at 0800 with 12-h delayed feeding. A 12:12 light:dark photoperiod was maintained. Four pigs were held per pen, and all pigs were given ad libitum access to a 20% CP corn-soybean meal diet with 15% dried whey throughout the 28-d study. The interactions between weaning and feeding times were not significant. During the 28-d period, pigs weaned at 2000 consumed 5% more feed (P less than .10) and grew 6% faster (P less than .05) than pigs weaned at 0800. Feed to gain ratios were similar for both time treatments. Variance of ADG within pens as measured by range, logarithm of variance, and CV were generally smaller for pigs weaned at 2000 than for pigs weaned at 0800 with no effect of feeding time. Pigs fed immediately after weaning and those delayed for 12 h had similar overall feed consumption, ADG, and feed to gain ratios. Weaning pigs in the evening enhanced performance, perhaps by better matching the normal diurnal eating and activity patterns and weaning time.

Pigs weaned at 21 d of age (n = 72) were fed a 20% CP corn-soybean meal-based diet (control) with 1.5% fumaric or 1.5% citric acid added to observe the effect of these acids on the pH, chloride ion concentration (Cl-), VFA profile, and microflora population in the stomach, jejunum, cecum, and lower colon contents at -2, 0, 3, 7, 14, and 21 d postweaning. Feeding organic acids had no appreciable effect (P greater than .10) on stomach jejunum, cecum, or lower colon pH, Cl-, VFA profile, or microflora populations, except for increasing the concentration of fumaric acid in the stomachs of pigs fed fumaric acid. The pH of the gastrointestinal tract generally decreased from -2 to 21 d postweaning with no corresponding change in Cl- over time. No age effects on total anaerobic culture counts were observed except in the stomach, where counts decreased from -2 to 3 d postweaning. Clostridia counts generally decreased after weaning in all intestinal sections. Lactobacillus counts were usually lower at d 0 and 3 and greatest at d 7 postweaning in the stomach, jejunum, and lower colon, but no age effect was observed for concentration of cecum lactobacilli. Escherichia coli counts generally increased after weaning to 3 and 7 d postweaning. Intestinal content measurements were affected by postweaning age but were not affected by feeding organic acids.

Three long‐term field experiments were established in the spring of 1978 and continued through 1988 to evaluate corn (Zea mays L.) response to high Cu levels from Cu rich swine manure and CuSO4 applications. The field research was conducted on soils with diverse properties, i.e., on a Bertie fine sandy loam (fine‐loamy, mixed, thermic, Aquic Hapludults), a Guernsey silt loam (fine, mixed, mesic, Aquic Hapludalfs), and a Starr‐Dyke clay loam (fine‐loamy, mixed, thermic Fluventic Dystrochrepts‐clayey, mixed, mesic, Typic Rhodudults). Three treatments in the long‐term field experiments on the three soils were i) a control, ii) annual applications of Cu as Cu rich swine manure, and iii) annual applications of Cu as CuSO4 equivalent to that in the manure. After the 11 years, 1109 mt ha‐1 of wet Cu rich swine manure were applied for the manure treatment. The Cu rich manure, which contained an average of 1316 mg Cu kg‐1, was produced by swine fed diets supplemented with an average of 251 mg Cu kg‐1 as C...

Ten crossbred barrows (48.3 +/- 2.3 kg of initial BW) fitted with steered ileo-cecal valve cannulas were used to investigate the effects of supplemental microbial phytase on the apparent ileal digestibilities (AID) of AA, Ca, P, N, and DM, and the apparent total tract digestibilities of Ca, P, N, and DM. All diets were corn-soybean meal-based, and contained 0.44% Ca and 0.40% total P. Diets 1, 2, and 3 contained 12.0, 11.1, and 10.2% CP, respectively. Diets 4 and 5 had the same ingredient composition as diet 3, plus 250 and 500 U/kg phytase (Natuphos), respectively. Pigs were randomly allotted to 1 of 5 dietary treatments in a paired 5 x 5 Latin square with an extra period to test for carryover effects. Each 14-d period consisted of a 7-d adjustment followed by a 3-d total collection, a 12-h ileal digesta collection, a 3-d readjustment, and a second 12-h ileal digesta collection. Pigs were housed individually in metabolism pens (1.2 x 1.2 m). Water was supplied ad libitum, and feed was supplied at a level of 9% of the metabolic BW (BW(0.75)) per day in 2 equal daily feedings. As the dietary CP concentration increased, the AID of CP and all AA measured increased linearly (P < 0.05) with the exception of proline. In addition, the apparent total tract digestibilities (grams per day) and retention of N (grams per day) increased linearly (P < 0.01) with increasing CP levels. Supplementing diets with phytase increased the AID of Ca (P < 0.01), P (P < 0.001), CP (P = 0.07), and the AA (P < 0.10) Gly, Ala, Val, Ile, Thr, TSAA, Asp, Glu, Phe, Lys, and Arg. Protein and phytase response equations were generated for those AA affected (P < 0.10) by both CP level and phytase supplementation. Based on these equations, 500 U/kg of phytase can replace 0.52 percentage units of the dietary CP, which includes a 0.03 percentage unit improvement in Lys AID. The results of this study show that supplementing pig diets with microbial phytase improves CP and AA digestibilities in addition to Ca and P digestibilities.

Twelve crossbred barrows (initial BW of 59.7 kg) were used in nutrient balance trials to investigate the influence of adding two Bacillus products (Biomate 2B and Pelletmate Livestock, Chr. Hansen's Biosytems) to a 14% CP corn-soybean meal diet (.64% lysine, .6% Ca and .5% P). A 3 x 3 Latin-square design with an extra period was used. Treatments were as follows: 1) basal diet; 2) basal + Biomate 2B (BAC1); and 3) basal + Pelletmate Livestock (BAC2). After a 7-d adaptation to metabolism crates, each 10-d period consisted of 5 d of diet adjustment followed by 4 d of total collection and 1 d for change-over. Both BAC1 and BAC2 were added at a level of .05% to supply approximately 3 million colony forming units per gram of diet. Pigs were fed twice daily at a daily rate of 3.2 to 3.5% of BW. Feeding BAC1 or BAC2 elevated (P.001) fecal Bacillus spore counts at the end of each collection period, but the effect on number of coliforms and lactic acid bacteria was not as consistent; coliform counts tended to be decreased (P.10) when BAC2 was fed, but not (P.10) when BAC1 was fed. The number of lactic acid bacteria was increased (P.05) when BAC1 was fed, but not (P.10) when BAC2 was fed. Body weights were similar among all treatments for all periods. There was no carry-over or pretreatment effect (P = .50). Digestibility coefficients of DM, neutral detergent fiber, acid detergent fiber, ash, and N and retention of N were not affected (P = .40) by feeding Bacillus products.

Two 5-wk trials using 176 weanling pigs (average initial weight of 8.3 kg and age of 31 d) were conducted to examine the effect of feeding varying levels of dietary Cu from copper sulfate (CuSO4) or a copper lysine complex (CuLys) on performance, mineral stores, serum copper, and serum mitogenic activity. Dietary treatments were 0 (15 mg/kg of Cu in basal diet), 100, 150, or 200 mg/kg of supplemental Cu from CuSO4 or CuLys. Average daily gain and ADFI increased linearly (P.01) with increasing dietary levels of Cu during wk 1 to 2, 3 to 5, and 1 to 5, with no difference (P.10) between the Cu sources. Overall gain:feed ratios were not consistently affected by Cu source. Dietary Cu linearly increased liver, kidney (P.001), and brain (P.05) concentrations of Cu. In the liver, the linear response to supplemental Cu differed between Cu sources (P.001); pigs fed 200 mg/kg of Cu from CuLys had the highest concentration of Cu. Serum Cu concentrations increased linearly during wk 1 to 2 (P.01), 3 to 5, and 1 to 5 (P.001), with no difference (P.10) between sources. Serum mitogenic activity increased linearly during wk 1 to 2 and 1 to 5 (P.05). Growth performance was linearly improved as the dietary level of Cu increased from 15 to 200 mg/kg, with similar responses for both Cu sources. Serum and tissue concentrations of Cu were generally equally affected by the two Cu sources, except liver Cu concentration, which was onefold higher for pigs fed 200 mg/kg of Cu as CuLys.

Three experiments were conducted using crossbred weanling pigs (7.2 to 8.6 kg; 25 to 29 d of age) to determine the effect on performance and nutrient digestibility of.75% yeast culture (YC) additions to starter diets containing whey or one of two fiber sources. An 18% CP corn-soybean meal basal diet was used in all experiments. In Exp. 1 (n=192), the addition of YC did not affect ADG, ADFI, or gain: feed ratios (G:F) of pigs fed diets without or with 15% dried whey in two 5-wk trials. In Exp. 2 (n=174), ADG and ADFI were not affected by YC addition to diets containing no added fiber, 8% soybean hulls (SH), or 8% peanut hulls (PH) in two 5-wk trials. The addition of SH or PH did not affect ADG or ADFI; however, a YC×SH interaction (P

A cooperative regional study involving 850 litters was conducted at five experiment stations (Arizona, Florida, Oklahoma, Texas, and Virginia) to assess the effects of feeding 220 mg/kg of chlortetracycline (CTC) from 1 wk before to the initiation of the breeding season to 15 d after the breeding season and(or) from 110 d of gestation through lactation on reproductive performance of sows (2 x 2 factorial). Sows were fed 1.82 kg/d (2.27 kg during December, January, and February) during the breeding period and before farrowing. Feed was consumed on an ad libitum basis during lactation. Feeding CTC during the breeding season increased litter size at birth (10.8 vs 10.3; P.05) and decreased feed consumption (5.4 vs 5.5 kg/d; P.05) in the subsequent lactation period. Feeding CTC during lactation reduced lactation weight loss in sows (4.3 vs 6.1 kg; P.07). Feeding the antibiotic at breeding had no effect on conception rate; however, feeding the antibiotic during lactation improved subsequent conception rate at the first service (80 vs 73%; P.10) and overall conception rate (89 vs 84%; P.05). This indicates that some carryover effect of feeding CTC during lactation occurred during the subsequent breeding period. Station x treatment interactions were observed for survival rate to 21 d (P.05) and to weaning (P.06). Overall, survival rates were not greatly affected by antibiotic feeding. No treatment interaction was observed for any trait measured, indicating that the effects of CTC during the breeding and lactation periods were independent.(ABSTRACT TRUNCATED AT 250 WORDS)

Four trials were conducted using crossbred pigs (n = 308) to determine the effects of Zn acetate injection near weaning on serum Zn concentrations and performance. In Trial 1, 78 pigs (BW of 5.1 kg and age of 18 d) were injected i.m. 3 d before weaning with either 3 mg of Zn from Zn acetate (in saline) per kilogram of BW or saline. Serum Zn concentrations were higher (P < .05) for Zn-injected pigs at 1 wk postweaning than for controls. In Trial 2, 96 pigs (BW of 7.2 kg and age of 26 d) were used to compare time of i.p. injection of Zn (weaning or 12 h postweaning) and amount of Zn injected (0, 3, or 4 mg of Zn/kg of BW). Serum Zn concentrations were higher (P < .01) in Zn-injected pigs 1 d after injections and remained higher than those in controls until after wk 2. In Trial 3 (n = 30, BW of 6.9 kg and 24 d of age), pigs that were injected with 3 mg of Zn/kg BW i.p. 3 d postweaning had lower (P < .05) ADG and ADFI and lower (P < .01) gain/feed from d 4 to d 7 postweaning than controls. Zinc-injected pigs had higher (P < .05) serum Zn concentrations at d 7. In Trial 4, 104 pigs (BW of 6.4 kg) were used in a 2 x 2 x 2 factorial arrangement of treatments: 1) regrouped 3 d before weaning or not regrouped, 2) Zn injections (3 mg i.p.) or placebo, and 3) time of injection, 2 d before or 1 d after weaning. All pigs were weaned at 23 d of age.(ABSTRACT TRUNCATED AT 250 WORDS)

A total of 228 crossbred weanling pigs (average age of 25 d and BW of 6.44 kg) were used in two trials to evaluate the responses to sex, diet acidity, protein level, and source of calcium on the performance, gastrointestinal digesta measurements, bone measurements, and carcass composition. Diet acidity was manipulated by varying the sources of supplemental phosphorus in the diets. Trial 1 (5 wk) was conducted as a 2 x 3 x 2 factorial to evaluate sex (gilts and barrows), diet acidity (pH 5.9 and .90% P, pH 6.1 and .63% P, and pH 6.9 and .63% P), and level of protein (16 and 22% CP). In Trial 2 (6 wk), diet acidity (pH 5.5, 5.9, and 6.8, all with .7% P) and Ca sources (CaC03 and CaS04) were used with gilts and barrows. The sex x diet acidity interactions were significant for ADG in both trials. Barrows seemed to respond to both the more acidic diets and the buffered phosphate diets even though the pH was less acidic than that of the unbuffered diets. Gilts responded only to the more acidic diets. In Trial 1, gilts ate more and grew faster (P < .05) than barrows, but no sex effects on performance were observed in Trial 2. Pigs fed 22% CP diets grew faster (P < .OOl) and more efficiently (P < .001) than did pigs fed 16% CP diets, but protein level x diet acidity and protein level x sex interactions were not significant. Stomach digesta DM, pH, and titration value were not consistently influenced by sex and diet acidity in Trials 1 and 2, by protein level in Trial 1, and by calcium source in Trial 2. Only the sex x diet acidity interaction for stomach DM tended to be significant in both trials; gilts fed the less acidic diets had the lowest DM, whereas barrows fed the more acidic diets had the lowest DM values. Although not significant in every case in both trials, bone (average of metacarpal and metatarsal) volume was lower and specific gravity and shear stress values were higher for gilts than for barrows. Pigs fed 16% CP diets had higher specific gravity (P < .05) and stress (P < .06) values than pigs fed 22% CP diets. A protein level x diet acidity interaction (P < .03) for stress suggested that pigs fed 22% CP diets were unaffected by diet acidity, whereas pigs fed 16% CP had the highest stress values when fed the more acidic diet and the lower P level. Pigs fed CaC03 diets had higher (P < .08) stress than those fed Cas04 diets. Longissimus muscle area and backfat thickness were slightly influenced by sex, diet acidity, protein level, or calcium sources. In summary, manipulation of diet acidity had minimal effects on gastrointestinal digesta and bone measurements and carcass leadfat composi- tion, but body weight gain favored the more acidic diets; gilts had a greater response to diet acidity than did barrows

A bioassay system was developed to measure porcine serum mitogenic activity, which is an indicator of growth factor activity. A MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazoliumbromide++ +] cell proliferation assay was used to monitor cell growth. In comparison with electronic cell counting, this bioassay system is sensitive, economical, and semi-automatic. A non-fusing myoblast cell line, BC3H1, was used, making it possible to increase seeding density and thus improve precision. The assay was carried out in 96-well microplates with automatic reading and data processing by a computer-controlled ELISA reader. Results were highly correlated with Kotts' method. This assay system is of potential value in studying growth regulation in pigs.

Crossbred female swine (n = 393) were used in a multiparity study at five experiment stations to evaluate the effects of dietary supplementation of folic acid (FA) on serum folates status and reproductive performance. The dietary treatments were a corn-soybean meal basal diet (calculated FA, .34 ppm) supplemented with 0, 1, 2, or 4 ppm FA. Experimental diets were fed continuously from a minimum of 21 d before first mating throughout the entire study. At one station, blood samples for radioimmunoassay determination of serum folates concentration were collected by vena cava puncture at mating, d 55 of gestation, d 110 of gestation, and at weaning. Stage of reproduction and dietary FA supplementation affected (P.005) serum folates concentrations. Serum folates declined from mating to d 55, remained low at d 110, and returned to higher levels at weaning. Linear increases (P.001) in serum folates with increasing level of dietary FA were observed at each reproductive stage. Over the course of the study, reproductive performance criteria including total pigs born, live pigs at birth and d 21, and individual pig and litter weight at birth and d 21 were not affected (P.10) by inclusion of FA in the diet. The number of days postweaning to estrus also was not affected by FA treatment. Under the conditions of this experiment, increasing level of FA in the diet had a pronounced effect in attenuating decreased serum folates concentration during gestation but was without benefit to reproductive performance.

Crossbred weanling pigs (n = 96, average initial weight, 8.4 kg) were used in a 6-wk trial using a 2 x 2 x 3 factorial arrangement of treatments to determine the effects of floor space allowance (.28 and .14 m2/pig), dietary Se (40 and 200 ppb), and dietary Zn (30, 80, and 250 ppm) on growth performance, clinical pathology measurements, serum minerals, and enzymes, liver enzymes, and adrenal weights. Pigs (four/pen) were given ad libitum access to feed and water. Body weight and feed consumed were recorded weekly, and heparinized blood samples were taken for the various assays. Three pigs per pen were killed at the end of the trial for gross examination of organs and tissues and for liver enzymes assays. Pigs housed with restricted floor space ate 21% less (P.001) and grew 18% more slowly (P.001) than pigs housed with adequate floor space, but their gain:feed ratio was 4% higher (P.08). Growth performance was not influenced by dietary Se and Zn treatments. There was no mortality in any of the treatments, and no visible gross abnormalities in organs and tissues at necropsy examination, except that more musculoskeletal bruising was observed for pigs housed with adequate floor space. This finding is supported by higher serum K concentration and creatine phosphokinase activity for pigs housed with adequate floor space. Corticosteroid activity and adrenal weights were similar for all treatments. Concentrations of blood Se and glutathione peroxidase were positively related to dietary Se levels, and serum Zn concentration was related to dietary Zn levels. Other effects of dietary Se and Zn on clinical pathology measurements were minimal and usually unexplained. Most two-way interactions of Se and Zn with floor space allowance were nonsignificant, which suggests that the main effects of Se, Zn and floor space were independent. Some hematologic values, serum metabolites, serum minerals, and serum and liver enzymes were decreased or increased, which is suggestive of stress of pigs housed with restricted floor space. However, most values were unchanged, and a few changed in the direction to suggest benefits of restricting space; all values were within an expected normal range.

Four trials using 312 weanling pigs (average initial weight, 7.2 kg) were conducted to examine the effect of Bifidobacterium globosum A (BGA) on the growth performance, scour scores, humoral and cell-mediated immune response, and pH and chloride ion concentration (CIC) of feces and gastrointestinal tract contents of pigs. Dietary treatments were 0, 5.0 x 10(4), 6.7 x 10(6), and 7.5 x 10(8) colony forming units (cfu) of BGA/d in Trial 1 and 0, 6.0 x 10(4), 5.0 x 10(5), and 5.0 x 10(6) cfu/d in Trials 2 through 4. Pigs fed the low or medium levels of supplemental BGA had a greater ADG (P.05) than control pigs throughout Trial 1, whereas ADG was quadratically increased (P.05) for the low or medium levels only during wk 3 to 5 for the pooled data for Trials 2, 3, and 4. The primary effect of dietary BGA additions on ADFI was a quadratic increase during wk 3 to 5 for Trial 1 (P.05) and for the pooled data of Trials 2 through 4 (P.10). Gain:feed ratios were generally unaffected by addition of BGA. Both ADFI and ADG tended to be decreased (P.10) at the highest level of BGA in all trials. Scouring was not severe in any of the trials and was not consistently affected by feeding BGA. The pH and CIC of gastrointestinal contents or feces were not influenced by the feeding of BGA.(ABSTRACT TRUNCATED AT 250 WORDS)

Three trials were conducted with recently weaned pigs (n = 198) to determine the effects of feeding different types of clay in conjunction with aflatoxin-contaminated diets. In Trial 1, pigs (n = 54; trial length 4 wk) were assigned to either an uncontaminated treatment (N C 1, 800 ppb of aflatoxin from contaminated corn (AC), or AC with one of four clays. In Trial 2 (n = 81; trial length 5 wk), pigs were assigned to NC, AC (500 ppb of aflatoxin from rice starch), or AC with one of seven types of clay. In both trials, pigs fed AC had decreased ADG and gain:feed ratios (P < .05) compared with controls. The clays differed in their ability to produce gains similar to those of controls. The clays did reduce changes in the serum measurements normally affected by aflatoxin, including albumin, total protein, gamma glutamyltransferase (GGT), and alkaline phospha- tase (ALP) levels, in a manner similar to their effect on ADG. In Trial 3, pigs (n = 63) were assigned to one of seven diets for 4 wk: NC, AC (800 ppb of aflatoxin) with no clay, AC with one of four levels of a treated Ca bentonite (.25, .5, 1, and 2%), or AC and .5% hydrated sodium calcium aluminosilicate. The addition of treated Ca bentonite to AC improved ADG (P < .05) and ADFI (P < .01) linearly. Gain:feed ratios were not affected by treatments. The inclusion of treated Ca bentonite to the AC diet linearly decreased aspartate aminotransferase (AST) levels and quadratically decreased ALP and GGT levels (P < .05). Feeding certain clays can effectively prevent some of the negative effects associated with feeding AC to wean- ling pigs, and some clays are more effective than others.

Three trials using 207 crossbred pigs were conducted to evaluate the effects of aflatoxin- contaminated corn on young pigs and to determine whether several nutritional and nonnutritional die- tary amendments would benefit performance or health in situations of aflatoxin B1 contamination. In Trial 1 using 90 pigs in a 49-d trial, linear (P < .01) and quadratic (P < .05) decreases in ADG were observed with increasing (0, 420, 840 ppb) dietary aflatoxin level. This growth decrease was associated with linear reductions ( P < .O 1) in ADFI and decreases in gain/ feed. Serum indicators of protein synthetic capabilities and of liver damage were also adversely affected. Improvements in growth rate for the total trial period in the presence of 840 ppb of aflatoxin were obtained with the addition of the 2 ppm of folic acid (P < .05) or 3% hydrated sodium calcium aluminosilicate (H S CAI ( P < .Ol); the magnitude of improvement was greater for the HSCA. The addition of HSCA to the contami- nated diet also restored the serum clinical chemistry profile to that exhibited by pigs fed the diet without contaminated corn. The addition of .6 ppm of Se to a basal diet containing .3 ppm of Se was generally without effect. In Trial 2, 63 pigs were used in a 42-d trial to further assess the effectiveness of both folic acid and HSCA, as well as of two sodium bentonites, in reducing the effects of aflatoxin from naturally contaminated diets (800 ppb of aflatoxin). Folic acid had no positive effect in this trial, but HSCA improved ADG ( P < .01) and all clinical chemistry indicators that had been negatively affected by the contaminated diet (P < .05). Both sodium bentonites provided as much improvement in ADG (P < .01) as the HSCA and also improved all clinical chemistry indicators that had been adversely affected by the aflatoxin (P < .05). In Trial 3 using 54 pigs in a 42-d trial, linear (P < .05) and quadratic (P < .025) improvements in ADG and ADFI and linear ( P < .05) improvements in those serum clinical chemistry indi- cators adversely affected by the contaminated diet were observed with additions of .25, 50, and .75% sodium bentonite to a diet naturally contaminated with 800 ppb of aflatoxin. There was no benefit to including more than 30% sodium bentonite to the contaminated diet. In situations of aflatoxin contami- nation, dietary alterations or additions can be made to diminish the adverse effects of aflatoxin.

Pigs weaned at 21 d of age (n = 72) were fed a 20% CP corn-soybean meal-based diet (control) with 1.5% fumaric or 1.5% citric acid added to observe the effect of these acids on the pH, chloride ion concentration (Cl-), VFA profile, and microflora population in the stomach, jejunum, cecum, and lower colon contents at -2, 0, 3, 7, 14, and 21 d postweaning. Feeding organic acids had no appreciable effect (P greater than .10) on stomach jejunum, cecum, or lower colon pH, Cl-, VFA profile, or microflora populations, except for increasing the concentration of fumaric acid in the stomachs of pigs fed fumaric acid. The pH of the gastrointestinal tract generally decreased from -2 to 21 d postweaning with no corresponding change in Cl- over time. No age effects on total anaerobic culture counts were observed except in the stomach, where counts decreased from -2 to 3 d postweaning. Clostridia counts generally decreased after weaning in all intestinal sections. Lactobacillus counts were usually lower at d 0 and 3 and greatest at d 7 postweaning in the stomach, jejunum, and lower colon, but no age effect was observed for concentration of cecum lactobacilli. Escherichia coli counts generally increased after weaning to 3 and 7 d postweaning. Intestinal content measurements were affected by postweaning age but were not affected by feeding organic acids.

Crossbred pigs (n = 144, average age and weight = 28 +/- 3 d, 7.5 kg) were used in two 6-wk trials to assess the effects of dietary pH and P source on growth performance, gastrointestinal digesta pH and chloride ion concentration (Cl-), and bone characteristics. Treatments were randomly allotted within blocks (based on weight within gender) to a 3 x 2 factorial arrangement with three dietary pH levels (5.4, 6.0, and 6.7) and two P sources: dicalcium phosphate (DCP) and defluorinated phosphate (DFP). Pigs fed the pH 6.7 diet had reduced ADG (P less than .01) and average daily feed intakes (ADFI; P less than .001) during wk 1 to 3 and overall compared with pigs fed the pH 6.0 diet, but ADG and ADFI were not affected when the pH 5.4 diet was fed. There was a dietary pH x P source interaction (P less than .05) for ADFI. Pigs had decreased ADFI as dietary pH was increased from 6.0 to 6.7 for both DCP and DFP, but ADFI was similar for the pH 6.0 and 5.4 diets with DFP, whereas ADFI was greater for the pH 5.4 diet with DCP. Dietary pH did not influence ADFI:ADG ratio (F:G; P greater than .05), and P source had no effect (P greater than .05) on either ADG, ADFI, or F:G.(ABSTRACT TRUNCATED AT 250 WORDS)

We conducted two trials (n = 144 and 96) to evaluate the response of feeding either ZnSO4 x H2O or a zinc-lysine complex (ZnLys) in combination with various lysine levels on growth performance, liver, kidney, and 10th rib Zn concentration, serum Zn humoral immune response and absorption of Zn (chromic oxide method) of young pigs. The following treatments were started after a 7-d postweaning adjustment during which all pigs were fed a common diet adequate in zinc. Diets were as follows: 1) basal 1 (B1), .8% dietary lysine without added Zn (basal contained 32 ppm Zn); 2) B1 plus 100 ppm Zn from ZnSO4; 3) B1 plus 100 ppm Zn from ZnLys, 4) basal 2 (B2), 1.1% lysine without added Zn; 5) B2 plus 100 ppm Zn from ZnSO4; 6) B2 plus 100 ppm Zn from ZnLys. In Trial 1 only, 100 ppm Zn from ZnSO4 (diet 7) or ZnLys (diet 8) was added to a .95% lysine basal diet. The basal 20% CP diet contained 9.0% corn gluten meal to lower the total lysine level. Within lysine level, all diets were made isolysinic by using crystalline lysine. Zinc sulfate, ZnLys, or lysine replaced dextrose in the basal diet. After 4 wk on test, one barrow in each pen was killed; liver, kidney, left 10th rib, and contents of the stomach, small intestine, and lower colon were removed for Zn analyses. Performance (ADG and ADFI) was only improved (P.05) in one of the two trials when either zinc source was added to the basal diets, but performance was higher (P.01) for pigs fed 1.1% lysine diets compared with .8% lysine diets in both trials. Serum Zn concentrations were lower (P.001) for pigs fed both dietary lysine basal diets without added Zn. The humoral response to sheep red blood cells and ovalbumin was not influenced (P.20) by lysine level, or Zn level and source. Pigs fed diets without added Zn had lower (P.001) liver, kidney, and rib Zn concentrations than pigs fed diets with added Zn regardless of Zn source. Dietary lysine did not influence liver Zn, but kidney (P.01) and rib (P.001) Zn concentrations were lower for pigs fed the higher lysine level. Digestibility coefficients of Zn were lower in the stomach for pigs fed diets without added Zn, similar among Zn levels and sources in the small intestine, and higher in the lower colon for pigs fed the basal diets without added Zn. Lysine level and Zn source did not influence Zn absorption. The ZnSO4 and a zinc lysine complex seemed to be equally effective in promoting growth performance, zinc absorption, and tissue stores of young pigs when diets contained deficient, adequate, or slightly more than adequate levels of lysine.

Ninety-six weanling pigs (initial BW = 9.3 kg, initial age = 37 d) were used in a 4-wk experiment to evaluate the response to three Ca: total (t) P ratios (1.2:1, 1.6:1, or 2.0:1) fed in combination with two P levels (.07 or .16% available that correspond to .36 or .45% tP) and two phytase levels (PY; 700 or 1,050 units/kg of diet). A 3 x 2 x 2 factorial arrangement of treatments was employed using a corn-soybean meal diet. Performance, serum mineral concentrations and alkaline phosphatase (ALP) activity, Ca and P digestibility and excretion, and bone mechanical measurements were examined. Average daily gain (P < .001), average daily feed intake (P < .01), and gain:feed (P < .05) were decreased linearly as the Ca:tP ratio became wider. The digestibility of P and Ca were decreased (P < .001) linearly as the Ca:tP ratio became wider. The digestibility of P (P < .001) and fecal P excretion (P < .01) were increased at the higher level of P. Increasing PY from 700 to 1,050 units (U)/kg of diet increased (P < .05) P digestibility and decreased (P < .01) P excretion but did not improve bone measurements. Shear force, stress and energy, and percentage of ash of both metacarpal and 10th rib linearly decreased (P < .001 to .05) as the Ca:tP ratio became wider, and bone measurements were generally greater for pigs fed the higher P level. Serum Ca concentration increased (P < .01) and the P concentration decreased (P < .001) as the Ca:tP ratio increased, but Mg, Zn, and ALP activity were not influenced by the Ca:tP ratio. Serum Ca and P concentrations were affected by PY supplementation over the 4-wk trial, but serum Mg and Zn concentrations were not affected by dietary treatments. Adverse effects of a wide Ca:tP ratio were greater at the low P diet for all responses. In addition, the activity of supplemental PY in diets seemed to be decreased as the Ca:tP ratio became wider and this negative effect of Ca:tP ratio seemed greater at the low P level, and seemed to parallel the effects of Ca:tP ratio on performance, P digestibility, bone, and serum measurements. Narrowing the dietary Ca:total P ratio from 2.0:1 to 1.2:1 led to an approximate 16% increase in phytase efficacy for improving performance, digestibility, bone measurements, and serum Ca levels.

Three trials using 300 pigs were conducted to establish response surfaces for effects of calcium and phosphorus (Ca/P) levels and of time on postweaning pig performance. Five dietary Ca/P levels (70, 85, 100, 115 and 130% of the NRC [1979] estimated dietary Ca and P requirements) were fed from weaning to market weight. Twelve replicates, each consisting of five pigs, were used across the three trials, and one pig per replicate was slaughtered every 4 wk following the start of the trials. Efficiency of feed utilization (G:F) was insensitive to diet within the range of Ca/P levels used, whereas ADG and average daily feed intake (ADFI) were linearly (P less than .01) and quadratically (p less than .01) related to both diet and weigh period. Asymptotic models relating continuous effects of total Ca + P intake (average grams per day of Ca + P) relative to the NRC estimated Ca + P intake and days on test at the midpoint of each weigh period were fitted to the data and used to derive response surfaces for ADG and ADFI. Ninety, ninety-five and ninety-eight percent of maximum ADG, ADFI and G:F also were determined; 98% of maximum ADG was reached with a Ca and P intake of 99.8% of NRC Ca/P estimates, whereas Ca and P intakes of 95.3 and 83.5% of NRC estimates were required to produce 98% of maximum ADFI and G:F, respectively.

Tibia biopsies were taken from 75 live pigs at 4-wk intervals and from 251 slaughtered pigs to evaluate bone biopsy as a procedure for determining Ca/P status in pigs fed 70, 85, 100, 115 and 130% of the NRC (1979) estimated dietary Ca and P percentage requirements from weaning to market. Least squares means and SE of live and slaughter biopsy wet weight, ash weight and dry, fat-free ash percentage (DFF%) were compared at each time in each trial and found not to differ. Diet and time effects on ash weight, ash percentage of wet weight and DFF% of the biopsy core also did not differ greatly between slaughter and live biopsies and generally responded linearly and quadratically (P less than .01) to increasing Ca/P level and time. Biopsy measures were correlated (P less than .05) with third and fourth metacarpal and metatarsal length, bending and shear stress and DFF%. Means for slaughter biopsy DFF% did not differ greatly from the average of third and fourth metacarpal and metatarsal DFF% from slaughter pigs. Means for live and slaughter biopsy DFF% were lower than those for whole bones for the 70 and 85% NRC estimated Ca/P levels, but not for the 100, 115 and 130% NRC levels. Bone biopsy offers potential as a reliable noninvasive procedure for monitoring Ca/P status of swine from weaning to market, but it needs further study for use in Ca/P research in swine.

Three trials involving 251 crossbred pigs were conducted to establish response surfaces for effects of Ca/P levels (70, 85, 100, 115 and 130% of NRC [1979] estimated requirements) and time (weaning to market) on bone criteria and to compare bending and shear bone testing. Nine replicates, each consisting of five pigs, were used over the three trials. One pig per replicate was slaughtered every 4 wk following the start of the trials. Third metacarpals and metatarsals (3M) and fourth metacarpals and metatarsals (4M) were collected at slaughter; the bone length, bending or shear stress, and dry, fat-free ash percentage (DFF%) were determined. Most bone criteria increased (P less than .01) at a decreasing rate (P less than .05) in response to increasing dietary Ca/P intake and increased linearly (P less than .01) with time on test, although bone length and stress increased at a decreasing rate with time on test. Asymptotic models relating continuous effects of total Ca + P intake ratio (CAP; expressed as a percentage of NRC) and number of days on test before slaughter to bone measurements were fit to least squares slaughter time by diet means. Bone length and DFF% reached 98% maximum at or near 100% the NRC estimated CAP level; however, to reach 98% of maximum bone shear and breaking stress higher CAP levels were required. Shear testing of bones was more desirable than bend testing as a method of determining bone strength due to reduced variability, better discrimination of Ca/P and time effects and ease of calculation.

Three trials were conducted with 216 Yorkshire x Duroc x Hampshire crossbred pigs (equal males and females) weaned at 3 to 4 wk of age (avg 7.4 kg initially) to determine the effectiveness of aspirin in an 18% CP corn-soybean meal starter diet (with and without soybean oil in Trial III) for improving postweaning performance and reducing scours. When aspirin levels common to all trials (0, 250 ppm) or common to Trials II and III (0, 125 and 250 ppm) were compared, improvements in ADG (P less than .10) and daily feed intake (P less than .05) were observed with no effect on efficiency of feed utilization. There was a quadratic effect of aspirin (P less than .10) in Trials II and III, the trend suggesting that the response to 125 ppm was as effective as the response to 250 ppm aspirin. The addition of soybean oil in Trial III did not enhance the response. In all trials, scouring was reduced (P less than .05) when pigs were fed 125 or 250 ppm aspirin; the improvement was greatest for 125 ppm aspirin after 5 d on test. Pooled data suggested no effect (P greater than .10) of aspirin on hemoglobin concentrations and blood clotting times; slightly higher (P less than .10) hematocrit values and DM content of colon digesta occurred in pigs fed 125 ppm aspirin vs controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Crossbred gilts (n = 288) were weaned at 4 to 5 wk of age and retained through three parities. They were used to determine the effects of feeding restricted energy (ad libitum vs 75% ad libitum) and elevated calcium-phosphorus levels (100 vs 150% of the dietary percentage suggested by NRC, 1979) from weaning to 100 kg of body weight on subsequent sow gait characteristics obtained from 16-mm motion pictures. After 100 kg, all females were fed and managed similarly throughout breeding, gestation and lactation. At 50 and 100 kg body weight and 21 d after weaning, females were filmed from the side and rear as they walked on a treadmill (traveling at the rate of .90 cm/s with zero slope) using two 16-mm Arriflex cameras. Objective measurements were taken from the film by projecting it on a reverse screen. Visual appraisal of structural soundness were scored subjectively for each female at each time period. The front foot pastern angle was correlated positively with structural soundness scores, suggesting that sows with smaller angles (more sloping) were given more desirable soundness scores. Early dietary energy and Ca-P levels did not influence number of sows completing three parities or culled for various reasons, front and hind pastern angles, the angles at the hock and carpal joint or rear view measurements, but sows fed ad libitum to 100 kg had a larger frame size even after three parities. Sows that survived three parities tended to have larger body capacity (girth diameter and width across hams) and smaller front and bind pastern angles and angles of the carpal joint and hock at maximum flex than did culled sows. Structural soundness scores did not differ between culled and surviving sows.

Three trials using 156 Yorkshire x Hampshire x Duroc crossbred pigs (avg initial wt, 7.9 kg) were conducted to evaluate the effects of two supplemental dietary vitamin E (11 vs 220 IU/kg of diet) and weaning age (21, 28 or 35 d) on performance and immunocompetence of pigs. Supplemental vitamin E (220 IU/kg of diet) increased (P less than .01) serum concentrations of vitamin E for all weaning ages compared with pigs fed 11 IU of vitamin E/kg of diet. However, supplemental vitamin E did not affect performance, serum cortisol concentration or the primary and secondary antibody response to sheep red blood cells. As weaning age increased, weekly ADG and avg daily feed intake increased linearly (P less than .01). Cortisol levels decreased during the 1st wk following weaning and then increased linearly (P less than .01) over time; pigs weaned at 35 d of age had higher (P less than .01) cortisol values initially and over time than pigs weaned at 21 and 28 d. Pigs weaned at 35 d had a higher (P less than .01) primary response to sheep red blood cells than pigs weaned at 21 and 28 d of age, but this effect was not observed for the secondary response. There were no interactive effects (P greater than .10) of dietary vitamin E level and weaning age. In summary, the highest level of supplemental vitamin E increased serum vitamin E concentration but did not affect performance, cortisol levels or one test of the immune response, antibody titers to red blood cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Data from 116 females previously fed a corn-soybean basal diet with 0 or 220 micrograms supplemental biotin/kg during growth and development were used to study the influence of 0 (NB) or 440 (SB) micrograms of supplemental biotin/kg to corn-(C) or wheat-(W) based diets for gilts and sows housed in total confinement. Reproductive performance through four parities (total of 245 litters) and various sow and pig biochemical criteria were evaluated. Females fed W diets were older (P less than .07) at first estrus, farrowed litters that were lighter weight (P less than .01) at birth and that contained fewer (P less than .05) total and live pigs compared with females fed C diets. Biotin supplementation did not significantly influence (P greater than .10) farrowing and lactation performance; however, after the first parity, total and live pigs/litter at farrowing tended to be larger for SB females. Conception rate at first estrus postpartum was increased (P less than .07) by 9% and the average weaning to estrus interval was reduced (P less than .05) from 14.5 to 10.2 d with SB. Biotin supplementation increased (P less than .001) the biotin content of sow plasma, milk and liver, while sow liver pyruvate carboxylase activity was not altered (P greater than .10). Pigs farrowed by SB females had three- and fivefold higher (P less than .001) levels of plasma biotin at birth and 14 d of age, respectively; however, liver biotin levels at birth were not different (P greater than .10) for pigs from NB and SB females.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of three anaerobic swine waste lagoons of ground water quality was investigaed in the Atlantic Coastal Plain region. The lagoons studied were located on high-water-table soils with different textures. Ground water was sampled from wells, with unperforated casings, located at depths to 6 m and distances to 30 m from the lagoons. These samples were taken monthly from September 1974 through January 1975, and bimonthly thereafter through November 1975. Ground water also was sampled in November 1975 from shallow wells with perforated casings located at distances to 36.6 m from two of the three lagoons. Constituents determined to investigate ground water contamination were density of fecal coliforms and concentrations of Cl, Cu, Mn, NH/sub 4/-N, NO/sub 3/-N, PO/sub 4/-P, and Zn. Chloride, NH/sub 4/-N, and NO/sub 3/-N concentrations in ground water samples indicated that seepage entered ground water from each of the three lagoons. Rupute of lagoon seals leading to seepage was attributed to drying of exposed subsoil or embankment soil during recession of lagoon liquid levels and to gas release from miarobial activity in soil beneath the seal. Overall, a low level of ground water contamination occurred around a lagoon that was in operation for over 8more » years in Myatt very fine sandy loam with a clay subsoil, and a lagoon that was in operation 1 mo prior to this investigation in Dragston fine sandy loam with a sandy clay loam subsoil. Ground water contamination in excess of recommended drinking water standards for Cl and NO/sub 3/-N occurred around the third lagoon.« less

Body weight and gain data from eight studies conducted with weaner pigs to determine the relationship between stocking density and performance were used to evaluate the effect of various stocking densities on several factors which measure variation within pens. The initial weight of the pigs ranged from 5·7 to 8·3 kg and final weight ranged from 17·7 to 32·1 kg. There were 244 pens of pigs with floor space ranging from 0·11 to 0·28 m2 per pig. Average daily gain and body weight were depressed as stocking density increased. Natural logarithms of variance, coefficients of variation and ranges of average daily gains and body weights were not increased by stocking density. Body weights and daily gains appeared equally effective in measuring variance of weaner pigs housed at various densities. These results indicate that increasing stocking density within the range of densities tested does not cause a greater variation in body-weight gains.

Six pairs of pigs were fed a basal diet, a high-fiber diet, and a diet high in corn oil in different sequences to minimize the carry-over effect of diet. After 2 months on each diet, a fecal specimen from each pig was cultured on nonselective medium in roll tubes. Fifty colonies were randomly selected from each fecal sample, and isolates were characterized to identify a representative cross section of the fecal flora. The bacterial composition of the fecal flora differed between basal and high-fiber diets (P = 0.002) and between high-fiber and high-oil diets (P = 0.015). However, the floras were not significantly different between the basal and the high-oil diets (P = 0.135), nor were the floras of the 12 individual pigs (each on all three diets) statistically different (P = 0.103). Only 14 of the 160 observed taxa have been detected in the human fecal flora, and only 159 of 1,871 total isolates (8.5%) were members of described species. The most common isolate was a Streptococcus species similar to that reported by Robinson et al. (I. M. Robinson, S. C. Whipp, J. A. Bucklin, and M. J. Allison, Appl. Environ. Microbiol. 48:964-969, 1984), which was found in 34 of 36 samples and which represented 27.5% of all isolates. Lactobacillus, Fusobacterium, Eubacterium, Bacteroides, and Peptostreptococcus species were the next most common bacteria. Escherichia coli represented 1.7% of all fecal isolates, which is somewhat higher than the 0.1 to 0.6% observed in human feces cultured similarly with prereduced anaerobically sterilized media.(ABSTRACT TRUNCATED AT 250 WORDS)