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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.

Soil P buildup can be stopped by limiting swine manure application to the crop's P requirement Limiting application rates will increase manure disposal costs on many farms. Microbial phytase can improve the availability of P in corn (Zea mays L) and soybean [Glycine max (L.) Merr.] meal to swine and lower P concentration in manure. Potential net returns from microbial phytase were estimated for two representative swine farms when manure applications are limited to the crop's P requirement. Net returns were estimated as savings in swine lagoon liquid application costs plus savings in supplemental feed P costs minus costs of microbial phytase. The first farm, a low land-hog ratio farm, applied lagoon liquid at higher rates per acre to bermudagrass [Cynodon dactylon (L.) Pem var. dactylon] hay, while the second, high land-hog ratio farm, applied lagoon liquid at lower rates to corn. Microbial phytase was assumed to lower P in lagoon liquid by 27.75%. With manure applications limited to crop P requirement, microbial phytase reduces the land area required for lagoon liquid disposal from 98 acres to 71 acres on the low land-hog ratio farm and from 191 to 138 acres on the high land-hog ratio farm. Net return to phytase is $7334 ($0.49/hog) on the low land-hog ratio farm, and -$336 (-$0.02/hog) on the high land-hog ratio farm. The net return to phytase is sensitive to the price of hay or corn and the amount of P reduction in swine manure obtained with phytase. Phytase has the potential to reduce farm economic losses resulting from limiting manure applications to crop P requirements.

The present study was performed to evaluate the potential of microbial phytase and cholecalciferol (D3) for improving the utilization of phytate P and Ca and the influence of the Car:total (t) P ratio in a corn-soybean meal diet fed to broilers from hatch to 21 d of age. A 4 x 4 x 2 factorial arrangement of treatments was used: 1.1, 1.4, 1.7, and 2.0:1 Ca:tP ratio; 0, 300, 600, and 900 U of phytase/kg of diet; and 66 and 660 micrograms of D3/kg of diet. Another four treatments were included: the four Ca:tP ratios with 6,600 micrograms of D3 addition, but without phytase. Added phytase linearly increased (P0.001) BW gain, feed intake, toe ash content, and P and Ca retention; these measurements were negatively influenced by widening the dietary Ca:tP ratio, and synergetically improved by addition of D3. Increasing the Ca:tP ratio decreased (P0.001) all measurements in the presence or absence of supplemental phytase and D3. Dietary Ca:tP ratios between 1.1:1 to 1.4:1 appears critical to the efficient use of supplemental phytase and D3 for improving the utilization of phytate P and Ca. The addition of D3 in corn-soybean meal diets indicated a potential for improving the utilization of phytate P and Ca by increasing Ca and P retention by about 5 to 12% in birds, which led to an increase in toe ash content (P0.03). The enhanced phytate P utilization (P0.001) was also observed during assay of the phytase activity in the mixed diets with an addition of D3 and without added phytase. In summary, the findings of this study suggested that phytase, D3, and Ca:tP are important factors in degrading phytate and improving phytate P and Ca utilization in broilers.

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.

The sites of supplemental phytase activity in the gastrointestinal tracts (GIT) of young pigs fed added microbial phytase were determined in two tests. In Test 1, samples of diets and GIT (stomach, upper and lower small intestine) contents were taken from pigs (BW = 20.3 kg) that had been fed a soybean meal-based semi-purified diet containing two levels of available P (0.5 and 1.6 g kg−1 aP), without or with added microbial phytase (1050 U kg−1 diet) for 5 weeks. There was no detectable phytase activity in the diets and GIT contents of pigs fed the basal diets without added phytase, and phytase activity did not differ for diets or GIT contents between the two dietary P levels. For pigs fed diets with added phytase, phytase activity in the digesta from stomach was higher (P < 0.001) than that from upper small intestine (51 or 31% of diet activity). No phytase activity was detectable in the digesta of the lower small intestine. In Test 2, samples of diets and GIT contents were taken from young pigs (BW = 16.7 kg) that had been fed a corn and soybean meal diet with added microbial phytase (750 U kg−1 of diet) containing one of three levels of citric acid (0, 15, and 30 g kg−1) for 4 weeks. Adding 30 g kg−1 citric acid decreased (P < 0.06) phytase activity in the stomach digesta; but there was no difference between the 15 and 30 g kg−1 added citric acid. About 40% of the added phytase activity remained in the digesta of the stomach from pigs fed the diet without added citric acid; whereas, only 27% of the phytase activity remained in the stomach digesta from pigs fed the diet with added citric acid. Again, phytase activity in the digesta from stomach was higher (P < 0.05) than that in digesta from upper small intestine (16 and 10% of added activity, respectively for diets without and with citric acid). As in Test 1, no phytase activity was detectable in lower small intestine digesta. In summary, the stomach is the site of highest added microbial phytase activity most likely because of a more favorable pH and lower protease activity.

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.

The effect of microbial phytase on N and amino acid (AA) digestibility and N retention was investigated in a 29-d trial using 480 Nicholas Large White Turkey female poults fed corn-soybean meal diets. A 2 x 2 x 2 factorial arrangement of treatments was used with 0.45 and 0.60% nonphytate P (nP), 22.5 and 28.0% CP, and 0 and 750 U of microbial phytase/kg of diet. At 0.45% nP, adding phytase to either 22.5 or 28.0% CP diets increased BW gain (P0.01), and percentage (P0.01) and weight (P0.10) of toe ash; at 0.60% nP, the magnitude of the effect of phytase was less (P0.10) than observed for 0.45% nP and inconsistent. Apparent and true ileal digestibility of N and AA was estimated by using chromic oxide as an indicator at Day 24. At 0.45% nP, adding phytase to 22.5% CP diets tended to improve the apparent and true ileal digestibility of N and AA, except cysteine or methionine; adding phytase to 28.0% CP diets increased the digestibility of N and most of the AA (P0.001 to 0.10). At 0.60% nP, adding phytase to 22.5% CP diets increased the apparent and true ileal digestibility of N and all the AA (P0.001 to 0.10), but did not change digestibilities at 28.0% CP diets. Adding phytase also increased (P0.001 to 0.10) apparent ileal digestibility of DM and P at 0.45% nP for both CP diets, but only for 22.5% CP diets at 0.60% nP. The total excreta were collected at Day 27 to 29. Adding phytase to 0.45% nP diets increased apparent utilization of DM (P0.01 to 0.10) and retention of N (P0.05 to 0.10) at both CP levels; retention of P was only increased (P0.10) at 22.5% CP. At 0.60% nP, adding phytase increased utilization of DM (P0.05) and retention of N (P0.10) only at 22.5% CP; P retention was not affected. In summary, microbial phytase enhanced growth performance, toe ash, ileal N and AA digestibility, and apparent N and P retention.

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.

Day-old male broilers (n = 384) were used in a 21-d trial to investigate the effect of microbial phytase on the retention and utilization of Zn. A corn-soybean isolate basal diet containing 20 ppm Zn was fed alone and supplemented with 5, 10, or 20 ppm Zn as ZnSO4.7H2O or with 150, 300, 450, or 600 U of phytase/kg of diet. Total excreta were collected during Days 18 to 20. Toe, tibia, and liver samples were taken at the end of the experiment. Adding Zn and phytase to the low Zn basal diet linearly increased BW gain and feed intake of broilers (P < 0.01). The gain to feed ratio was not changed by adding Zn but was decreased by adding phytase (P < 0.01). The amount of DM retained was linearly increased by adding Zn and phytase (P < 0.10), but DM retained as a percentage of intake was only increased by adding Zn (P < 0.05). The amount of Zn retained per bird was linearly improved by adding Zn and phytase (P < 0.01). Zinc retained as a percentage of intake was linearly decreased by adding Zn but was linearly increased by adding phytase (P < 0.10). Ash percentage of toe and tibia were not affected by adding Zn but were linearly improved by adding phytase (P < 0.10); however, the amount of ash in toe or tibia was increased by Zn (P < 0.05) and phytase (P < 0.01 for toe; not significant for tibia). The concentration and amount of Zn in toe and tibia were linearly increased by adding Zn and phytase (P < 0.001). The concentration of Zn in liver increased by adding Zn (P < 0.10) but was not significantly improved by adding phytase. The amount of Zn retained in liver was linearly improved by adding Zn and phytase (P < 0.05). Nonlinear or linear response equations of the effects of Zn and phytase levels were generated and used to calculate the Zn equivalency values. The average function of Zn equivalency values (Y, milligrams per kilogram) of microbial phytase (X, units per kilogram of diet) was developed: Y = 0.20 + 0.0082X. The results indicate that approximately 0.9 mg of Zn was released per 100 U of phytase over the range of 150 to 600 U of phytase.

The effects of feeding 2 ppm supplemental folic acid (FA) on fetal survival and development were assessed in sows (n = 32). Number of live fetuses and fetal survival at day 45 ± 3 of gestation was not influenced by FA. Fetal pig weight, length, protein and RNA content were increased (P

Male day-old turkey poults (n = 768) were fed 0, 300, 600, or 900 U of phytase/kg of a corn-soybean diet in combination with four Ca:total P (tP) ratios of 1.1, 1.4, 1.7, and 2.0:1, and two levels of nonphytate P (nP) of 0.27 and 0.36% in a 21-d trial. Dietary Ca:tP ratios were obtained by varying defluorinated phosphate and limestone at the expense of cornstarch. The calculated dietary percentage of phytate P was 0.266 for all diets. Phytase additions linearly increased (P0.05) BW gain, feed intake, gain:feed, toe ash content, and apparent retentions of Ca and P at each Ca:tP ratio and nP level, but the response was influenced by dietary Ca:tP ratios and P levels. The detrimental effect (P0.02) of widening the Ca:tP ratio was observed for all measurements at each phytase and P level, and was greatest at lower phytase and P levels. Widening the Ca:tP ratio from 1.4 to 2.0 decreased the phytase efficacy by 7.4 and 4.9%, respectively, for 0.27 and 0.36% nP diets, which was close to the decrease in the phytase activity in vitro by 7.5 and 6.7%, respectively. The largest responses to supplemental phytase were achieved when poults were fed diets with 600 and 900 U of phytase/kg diet, respectively, for 0.36 and 0.27% nP, and for Ca:tP ratios ranging from 1.1 to 1.4:1. Second-order translog equations were generated for the phytase, Ca:tP ratio, and P effect, and nonlinear and linear equations for the phytase and Ca:tP ratio effect. Based on an assessment for the R2 and P values of equations, BW gain, feed intake, toe ash content, and P retention were sensitive measurements of the response to phytase addition. Equivalent equations were developed to determine the P equivalency of supplemental phytase. About 652 and 963 U of phytase were equivalent to 1 g nP, respectively, for 0.27 and 0.36% nP diets in turkey poults from hatch to 21 d of age.

The relative bioavailability of P from seven sources was determined in relation to a standard dicalcium phosphate dihydrate (CaHPO4.2H2O) in a 21-d assay involving 1,320 broiler male chicks using several response criteria. The seven sources (Lucaphos-48, Lucaphos-40, Rukana, Cefkaphos-N, phosphoric acid, monocalcium phosphate monohydrate, or Biophos) were added to the basal diet (.40% total P and 1.10% Ca) at levels to supply .05, .08, .12, .17, .23, and .32% P. Two additional levels (.44 and .66%) of P from dicalcium phosphate dihydrate were included for the standards. The criteria selected to evaluate included tibia ash, tibia specific gravity, tibia shear force, toe shear force, and metatarsal shear force. Other criteria: weight, length, diameter, and volume of tibia; weight, volume, and specific gravity of metatarsus; and weight, volume, and specific gravity of toe were not selected because their response to increasing P levels were inconsistent and quite variable. Nonlinear (asymptotic and sigmoidal) regression equations were fitted to the data than linear equations. The ratios of regression coefficients were used to determine the bioavailability of various test phosphates relative to the reference standard. The results indicated that the response criteria used for the determination will considerably influence the relative bioavailability estimates of a P source. Body weight gain and toe ash percentage were found to be an equally or a more sensitive criteria for assessment of P availability than tibia ash. Tibia specific gravity, tibia shear force, toe shear force, and metatarsal shear force were of limited value as response criteria in P bioavailability assays based on standard error and difference required for significance.

A 3-wk feeding trial using 920 day-old turkey poults was conducted to evaluate the addition of seven levels of phytase (Natuphos; 0, 200, 400, 600, 800, 1,000, and 1,200 U/kg of diet) to diets containing three levels of nonphytate P (nP) (.27, .36, and .45%). A positive control diet contained .60% nP. Semi-purified basal diets contained soybean meal as the only protein source. The increase in BW gain from added phytase was greatest for the lowest nP diet (nP by phytase interaction, P < .001). At .27% nP, gains improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. At .36 and .45% nP, increases in gains were observed only for 200 U of phytase/kg of diet. The highest phytase addition to.36 and .45% nP diets produced gains equal to those of the positive control diet. Feed intake increases paralleled those of BW gains. Gain:feed was lowest for the .27% nP diets without phytase, but improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. The high incidence of leg disorders and high mortality (40%) observed for the poults fed the .27% nP diet without added phytase declined with the addition of 200 to 400 U of phytase/kg of diet. Ash percentage of toes and tibias increased as the levels of nP (P < .001) and phytase (P < .01) increased; the magnitude of the response to phytase decreased as nP in the diet increased, resulting in an nP by phytase interaction (P < .001). Tibial shear force and stress responded in a similar manner to increasing levels of nP and added phytase. Results show that 652 U of microbial phytase is equivalent to 1 g of P from defluorinated phosphate in turkey starter diets using soybean meal as the only source of phytate P. The response per 100 U of phytase decreased as the total amount of phytase added was 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)

Growth trials were conducted to determine the effects of Cr as chromium picolinate at various protein levels on performance of growing pigs. The effects of continued supplementation on sow fecundity and body weight changes through two parities also were examined. In Trial 1, 48 crossbred pigs (40.9 kg initial weight) were assigned to one of three diets (0, 250, or 500 ppb of added Cr). The only observed difference was an overall trend for an improvement in gain:feed when Cr was added to the diet (P < .10). In Trial 2, 105 crossbred pigs (14.5 kg initial weight) were assigned to one of seven treatments involving a combination of two factors: 1) lysine level at 100 or 120% of NRC (1988) requirement estimate and 2) added Cr level (0, 100, 200, 500, or 1,000 ppb). A Cr x lysine interaction (P < .02) for gain:feed existed that demonstrated that the addition of 200 ppb of Cr resulted in improved gain:feed at the 100% of requirement lysine level but not at the 120% of requirement lysine level. The addition of 200 ppb Cr also reduced backfat (P < .04) and increased longissimus muscle area (P < .04) regardless of lysine level in the diet.(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.

In Study 1, pigs (n = 54) weaned at 21 ± 2 d were fed a 20% CP corn-soybean meal based diet only (control) or with 1.5% fumaric or 1.5% citric acid. One half of the pigs on each treatment were orally challenged on days 3, 7 or 14 postweaning with 1010E. coli (0157:K88+) to observe the effects on scouring and on intestinal digesta pH, Cl− concentration, VFA and non-volatile acid profiles, and microflora concentrations in the stomach, jejunum, cecum and lower colon when pigs were necropsied 5, 9 or 16 d postweaning. The E. coli challenge increased (P − concentration, and lactobacillus or E. coli concentrations, but did increase (P − concentration increased (P

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.

In Study 1, 25-day-old crossbred weanling pigs (n = 144) were fed a 20% crude protein maize-soyabean meal basal diet. Supplementation with 1.5% citric acid tended to improve gain and the efficiency of feed utilization (F:G) during the first 4 weeks with no effect during week 5; 1.5% fumaric acid caused smaller and non-significant improvements in gain and F:G. Feed intake was unaffected by organic acids. The pH, chloride ion and volatile fatty acid concentration of intestinal contents from the stomach, jejunum, cecum and lower colon of 27 pigs killed at the end of Study 1 were not significantly affected by dietary organic acids. With the exception of fumarate, the concentration of non-volatile acids was not affected by diet. The stomach and jejunum of pigs given fumaric acid had a greater concentration (P < 0.05) of fumarate than those of pigs given the control and citric acid diets. In Study 2 (n = 192), no interactive effect of dietary fumaric or citric acid with a live microbial culture (Lactobacillus acidophilus) was observed. Fumaric acid supplementation increased (P < 0.03) gain and the microbial culture improved gain (P < 0.08) and F:G (P < 0.02) during the 5 week test; 1.5% citric acid had no effect. In conclusion, the addition of citric or fumaric acid and/or a microbial culture produced inconsistent improvements in gain and F:G, with little effect on intestinal digesta measurements.

Two experiments were conducted to evaluate systems of providing supplemental heat to newborn pigs during and after farrowing. In Exp. 1, 35 sows were randomly allotted to farrowing crates with two supplemental heat treatments: 1) two lateral 250-watt heat lamps; and 2) two lateral heat lamps, plus a 250-watt heat lamp behind the sow during farrowing. In Exp. 2, 72 sows were randomly assigned to farrowing crates with four supplemental heat treatments: 1) one lateral 250-watt heater; 2) one lateral heater plus a 250-watt heater behind the sow during farrowing; 3) a hover with 100-watt light bulb; and 4) a hover with light bulb plus heater behind the sow during farrowing. The average farrowing house temperature was 18.9 degrees C in Exp. 1 and 21.6 degrees C in Exp. 2. Results showed no significant treatment effects on preweaning pig survival or growth rates in either experiment. Thus, providing a heat lamp at the rear of the sow during parturition was not beneficial and would increase operating costs. Hovers have a higher initial cost than conventional heat lamps or heaters, but they would have a much lower operating cost. Hovers may offer swine producers a way of reducing energy costs without affecting preweaning pig survival and performance.

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...

Crossbred pigs (n = 144) were used at two geographical locations (mountain and coastal) to evaluate the effects of varied Na intake on growth performance, serum minerals and bone characteristics of growing-finishing swine (average initial body weight 24.5 kg) fed either defluorinated phosphate (DFP) which contained 5% Na or dicalcium phosphate (DCP) which contained −1 Na and 194 mg L−1 Na at the coastal location. Growth performance did not differ among treatments, with the exception of pigs fed the DCP diet without added Na (total Na, 0.01%) at the mountain location which had depressed daily gain, daily feed intake and feed per gain compared with all other diets. When metacarpals (MC) and metatarsals (MT) taken from barrows at slaughter were examined on a body weight-corrected basis, Na intake and P source did not consistently influence bone dimensional and strength characteristics. Pigs fed the DCP diet without added Na at the mountain location had a lower Na and higher Mg content of MC and MT, and serum Na and Ca concentrations were reduced while serum P, Mg and K concentrations were unchanged. Varying Na intake did not influence bone strength and mineralization, and the Na in defluorinated phosphate and drinking water is readily available for growing pigs. Key words: Sodium, phosphates, bone mineralization, pigs

1. 1. The mucus from 2-day-old and 3-week-old pigs was separated into polymeric mucus glycoprotein, degraded mucus glycoprotein subunit, and low-molecular-weight glycoprotein. 2. 2. The low-molecular-weight glycoprotein fraction contained significant amount of mannose. 3. 3. The degraded mucus glycoprotein subunit and the low-molecular-weight glycoprotein decreased in the mucus from older pigs.

The distal halves of third metacarpals from 93 crossbred pigs were used to determine the effect of hydration time (0, 30, 60 or 120 min) for frozen or thawed (2 h) bones on volume and specific gravity. Based on the findings of this study, a procedure for the determination of volume and specific gravity is suggested. Key words: Specific gravity, hydration, bone, pigs

Crossbred barrows and gilts (n = 434) were fed 70, 85, 100, 115 or 130% of NRC Ca-P recommendations from 10 to 105 kg to evaluate the influence of Ca-P levels, sex, and age on the subjective condition score of the articular cartilage of the distal humerus and distal femur. The frequency and severity of lesions increased over time and was similar among sexes. After 140 d on test (105 kg BW), fewer articular cartilage lesions were observed on the distal femur compared with the distal humerus (15 vs. 71%, respectively). Dietary Ca-P levels did not influence the development of these lesions. Key words: Articular cartilage, femur, humerus, swine, calcium, phosphorus

A deterministic simulation model was developed to help assess emergency environmental needs of swine nurseries by modeling short term power interruptions. The model accounts for heat exchange by conduction, convection, radiation and air infiltration. A sub-model, developed by the North Central Region Committee 179, was used to predict swine heat and moisture loss. The model was validated using a nursery constructed of concrete block. The model performed well for cases with a constant solar load but tended to overpredict temperature changes during periods of no solar load. Validation indicated that wind velocity had the most effect upon model error. Sensitivity analysis indicated that animal body weight, long wave emissivity, net energy content of the feed, and digestible energy content were the most sensitive inputs.

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.

Phytase may well be the miracle enzyme of the 1990s, as soybeans were described as the miracle crop for producing high quality plant protein in the 1940s. Dietary addition of microbial phytase or the inclusion of high phytase ingredients in pig, poultry and fish diets is now well documented to release a large portion of the naturally occurring phytate P, and thus greatly reduce the amount of inorganic P that must be added to meet the animal’s P requirement. The net result is a reduction in P excretion that can range from 20 to 50%. Microbial phytase was initially used as a tool to reduce P excretion because modern commercial production of pigs and poultry had led to large amounts of manure which, when applied to the land in excess, resulted in a build-up of nutrients in and on the soil. This had a potential for environmental pollution that continues to lead to legislation in many countries that require nutrient management plans for manure from these farms. It is becoming increasingly clear that the use of adequate amounts of phytase in most pig and poultry diets results in improved availability of Ca, Zn, protein/amino acids (AA) and energy. This is because seeds or products from seeds, which are the major ingredients in pig and poultry diets, contain 60–80% of the P in the form of phytic acid or phytate. Phytate is known to complex with other nutrients. Thus, the unavailable phytate P and nutrients complexed with it cannot be utilized and are excreted. This chapter will provide a brief review of phytate, phytase, and the effectiveness of microbial phytase in pig, poultry and fish diets for enhancing the utilization of P

Ninety-six crossbred pigs with an average weight of 9.0 kg were used in a 5-wk trial to compare the efficacy of genetically engineered Aspergillus ficuum phytase, expressed in Aspergillus niger (Natuphos) or in canola seed (Phytaseed), for enhancing the utilization of phytate P in corn-soybean meal-based diets fed to young pigs and to evaluate the safety of Phytaseed phytase. Three levels of the two sources of phytase (250, 500, or 2,500 U/kg of diet) were added to a corn-soybean meal basal diet containing .35% total P, .09% available P, and .50% Ca. There were six pens per treatment (one barrow and one gilt/pen), except that the diet without added phytase was fed to 12 pens of pigs. Pen feed consumption and BW were recorded weekly. During wk 5, pen fecal samples were collected for determination of apparent digestibilities of DM, Ca, and P. At the end of wk 5, all barrows were killed, and the 10th rib on both sides was removed for determination of shear force and energy. Thirty pigs (six from the diet without added phytase and the diets with 500 and 2,500 U/kg phytase from both sources) were randomly selected for gross necropsy and histologic evaluation of liver, kidney, and bone tissues. Both sources of phytase were equally effective in increasing (P < .05) daily gain, gain:feed, apparent digestibilities of DM, P, and Ca, and 10th rib measurements. Fecal P excretion was reduced with phytase addition. Feed intake was increased by phytase levels during wk 4 to 5. No significant abnormalities were seen in any of the 30 pigs necropsied. The fit of a nonlinear function revealed that most measurements were reaching a plateau at 2,500 U/kg phytase. In summary, based on performance, bone measurements, and digestibilities of P, Ca, and DM of young pigs, the efficiency of Phytaseed was similar to that of Natuphos for enhancing the utilization of phytate P in corn-soybean meal-based diets. General necropsy and histologic examination of tissues indicated no toxic effect of phytase.

This study was conducted to compare the efficacy of genetically engineered microbial (Natuphos) and plant (Phytaseed) phytase for enhancing the utilization of phytate P in corn-soybean meal-based diets fed to young broilers and to evaluate the safety of Phytaseed phytase. Three levels of each of the two sources of phytase (250, 500, and 2,500 U/kg of diet) were added to a corn-soybean meal basal diet containing 0.46% total P, 0.21% nonphytate P, and 0.92% Ca. There were eight cages per treatment (eight birds per cage for Weeks 2 to 3 and seven birds for Weeks 4 to 5), except for the basal diet without added phytase that had 16 cages. Cage BW and feed consumption were recorded weekly. During Week 5, cage excreta samples were collected for determination of apparent retention coefficients of DM, Ca, and P. At the end of Week 5, all birds were killed, and the left and right toes were removed for determination of toe ash weight and percentage. Forty birds (one per cage from the diet without added phytase and diets with 500 or 2,500 U phytase/kg from both sources) were randomly selected for gross necropsy and histologic evaluation of liver, kidney, and bone tissues. Addition of both sources of phytase resulted in similar increases (P0.05) of BW gain; feed intake; gain:feed; apparent retention of DM, P and Ca; and toe measurements. Phosphorus excretion decreased as phytase addition increased. No significant abnormalities were seen in any of the 40 broilers necropsied. Further, the fit of a nonlinear function revealed that most measurements reached a plateau at 2,500 U/kg. Based on performance, bone characteristics, and retention of P, Ca, and DM of young broilers, the efficacy of Phytaseed phytase was similar to that of Natuphos phytase for enhancing the utilization of phytate P in corn-soybean meal-based diets. General necropsy and histologic examination of liver, kidney, and tibial tissues revealed no adverse effects of phytase source or level.

An evaluation of three waterer treatments: (1) pig-trainer nipple waterers adjusted to drip water for 3 d postweaning; (2) pig-trainer nipple waterers adjusted to not drip; and (3) conventional non-drip nipple waterers did not indicate significant (P > 0.05) differences in weekly and cumulative average daily feed intake, average daily gain and feed per gain ratios of weanling pigs, suggesting no advantage for the use of drip waterers. Key words: Pigs, nipple drinkers, growth, feed intake, feed conversion

Male broilers (n = 416) were used to compare the efficacy of providing dietary phytase either as a commercial supplement or as a recombinant protein in transformed soybean. From 7 to 21 d of age, broilers were fed a basal diet containing 0.20% nonphytate P (nP) with additional supplementation by fungal phytase as Natuphos or as raw transformed soybeans expressing recombinant phytase at 400, 800, or 1,200 U/kg. For comparison, broilers were also fed the basal diet containing 0.08, 0.16, or 0.24 added nP. The basal diet was fed as the negative control. Diets were consumed ad libitum as a mash. All excreta were collected from each pen from 18 through 20 d of age, and the birds were killed at 21 d of age. Supplementing the basal diet with nP linearly increased body weight gain, feed efficiency, feed intake, toe ash weight and percentage, and tibia shear force and energy. Phosphorus digestibility decreased linearly as nP level increased, but P excretion increased. Dietary phytase linearly increased growth rate, feed intake, toe ash weight and percentage, tibia shear force and energy, and P digestibility, whereas excretion was decreased. Except for P digestibility, there was no difference in efficacy of responses for performance, bone mineralization, and P excretion between the two sources of phytase. It appears from this study that phytase can improve growth performance of broilers fed low nP diets when provided either as a commercial supplement or in the form of transformed seeds.

Two experiments using 413 crossbred growing-finishing pigs were conducted to assess the use of a commercial microbial phytase (Natuphos) in corn-soybean meal diets to improve phytate P bioavailability and thus reduce inorganic P supplementation and fecal P excretion. In Exp. 1 (n = 189), the following diets were used: 1) .50/.40% total P, respectively, for grower and finisher phases, and no phytase; 2) .40/.35% P and no phytase; 3) diet 2 plus 250 U phytase/kg; and 4) diet 2 plus 500 U phytase/ kg. The total Ca level was .58/.48% for diet 1 and .53/.43% Ca for diets 2, 3, and 4 in the grower and finisher phases, respectively. Feeding the low-P diet without supplemental phytase resulted in an overall 18% reduction in ADG (P < .05), 15% reduction in ADFI (P < .05), and 3% poorer feed efficiency (P < .08). Adding 250 to 500 U phytase/kg to the low-P diet restored ADG, ADFI, and feed conversion to levels not significantly different from and within 96% of that observed for pigs fed the adequate-P diet. The overall apparent digestibility of P was linearly (P < .01) improved with addition of 250 and 500 U phytase/kg to the low-P diet, but Ca and DM digestibilities were not affected by phytase or P level. In Exp. 2 (n = 224) the following diets were used: 1) .38/.33% total P, respectively, for grower and finisher phases, and no phytase; 2) .42/.37% P and no phytase; 3) .46/.41% P and no phytase; 4) diet 1 plus 167 U/kg phytase; 5) diet 1 plus 333 U/kg phytase; and 6) diet 1 plus 500 U/kg phytase. All diets contained .41/.36% Ca for grower and finisher phases, respectively. Pigs fed the low-P control diet grew slower (P < .01) and less efficiently (P < .10) than pigs fed diets with added P or phytase. With increasing levels of supplemental phytase or P there was a linear increase (P < .01) in ADG, digestibility of P, and digested P and a quadratic improvement (P < .05) in feed efficiency. Tenth rib mineralization based on shear force and ash were linearly increased (P < .08 to .001) as phytase or P was added to the low-P diet. There were generally no effects of P or phytase level on carcass quality. Using prediction equations derived from the response traits of ADG and P digestibility in Exp. 1 and ADG, P digestibility, and bone shear force in Exp. 2 to added phytase or P, we estimated that 500 U phytase released an amount of phytate P that was approximately equivalent to .87 to .96 g of P from dicalcium-monocalcium phosphate supplements. Fecal P excretion was estimated to be reduced 21.5%.

Four trials were conducted to determine the influence of feeding 200 ppb Cr as chromium picolinate (CrPic) on DM digestibility, N balance, and carcass traits of growing-finishing pigs. A 15% CP corn-soybean meal diet was fed during the grower phase, and a 13% CP corn-soybean meal diet was fed during the finisher phase. In each of three trials, crossbred barrows (six littermate pairs) were used for two N balance periods (end of grower, 61.3 kg; end of finisher, 98.9 kg). After the second balance period, all the barrows were killed and carcass data were collected. Initial and final BW were 23.5 and 104.9 kg, respectively. Growth rate was similar for control and CrPic-fed pigs in all trials. The rate of N absorption was increased by feeding CrPic (P < .05), but N retention was increased only numerically (P = .14). Dry matter digestibility was also increased by feeding CrPic (P < .02). Dressing percentage and backfat thickness at the 10th and last rib did not differ between treatment groups. Longissimus muscle area was larger (P < .05) for pigs fed CrPic. In Trial 4, crossbred barrows (six littermate pairs; initial BW, 82.0 kg) were used in a switch-back design with an extra period. Digestibility of DM (P < .02) and absorption of N (P < .06) were improved with only a numerical increase (P = .22) in N retention. No carryover effect was observed. These findings show that pigs fed 200 ppb Cr from CrPic can have larger longissimus muscle areas and that Cr supplementation improved N absorption and DM digestibility.