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In 1995, an antibiotic (ANT) was used in starter, grower, and withdrawal (WD) feeds by 94.3, 98.2, and 75.1% of broiler production units, but by 2000, ANT use had declined to 64.8, 66.9, and 48.1% respectively. Roxarsone (ROX) was used in the starter and grower feeds by 69.8 and 73.9% of production units. Bacitracin (BAC) was used more frequently than other antibiotics in the starter and grower feed. Virginiamycin (VIR) was used most frequently in the WD feed. Most units (69.4%) reported use of two different antibiotics. The use of programs comprising two ANT decreased, whereas programs with a single ANT increased during the period of study. A combination of ionophore (ION) + ROX + ANT was employed most frequently in the starter and grower feeds, whereas an ANT alone was used most frequently in the WD ration. The use of ION + ROX + ANT declined from 1995 to 2000, but use of ION + ROX increased. There were no significant differences in calorie conversion whether plants used ION + ROX + ANT, ION + ROX, or ION + ANT. The number of days to rear birds to 2.27 kg was significantly greater for production units using ION + ROX. Mortality was lower for units that used ION + ROX + ANT and ION + ROX than for those that used ION + ANT. Production units that used ION + ANT were more likely to rear birds to a weight greater than 2.5 kg than to 2.0 to 2.5 kg. Units in the South and Central states were more likely to use an ION + ROX than those in the Northeast and Atlantic states, whereas for ION + ROX + ANT the reverse was the case. The cost of medicating with ION + ROX + ANT decreased from 1995 to 1998.

We determined the effects of forage type on isoenzymes of lactate dehydrogenase (LDH) and glucose 6-phosphate dehydrogenase (G6PDH). Forty-eight crossbred steers were randomly allotted to replicated pastures consisting of fungus-infected (Neotyphodium coenophialum) fescue or fungus-free fescue each with or without ladino clover overseeding. At the end of the 180-d grazing period, serum was harvested from the steers. Steers were finished in a feedlot and slaughtered after approximately 150 d in the feedlot. Isoenzymes for LDH and G6PDH were separated using PAGE. Five LDH isoenzymes (L1-15) were typically detected. Isoenzyme L1 (most anodic) had the greatest area percent as detected by laser densitometry (72, 12, 10, 5, and 7%, respectively, for L1, L2, L3, L4, and L5). Four proteins had G6PDH activity (G1-G4) with G2 having the greatest area percent (15, 52, 27, and 14, respectively, for G1, G2, G3, and G4). Isoenzymes within a dehydrogenase were correlated (P < .05). In addition, area percentage of L1 was correlated (P < .05; r = .34) with area percentage of G2, and area percentage of L4 was correlated (P < .07; r = .73) with area percentage of G1. Area percentages of L1, L2, and L3 were affected by an interaction (P < .09) of forage types. Body weight gains for steers grazing endophyte-infected fescue were depressed (P < .05); however, steers compensated with increased (P < .05) weight gains during the finishing phase. Fungal toxins produced by Neotyphodium coenophialum may alter an animal's metabolism, growth, and development via shifts in reducing equivalents (NADH).

Wheat (Triticum aestivum L.), oat (Avena sativa L.), and rye (Secale cereale L.) were overseeded into a dormant bermudagrass (Cynodon dactylon (L.) Pers.) sod and harvested at 3-wk intervals throughout March, April, May, and early June. Plant growth stage was documented for each forage on each harvest date, and harvested forages were evaluated for forage quality characteristics. Degradation kinetics of DM and NDF for these forages were evaluated by the in situ method. Fractional degradation rates for DM and NDF in all three species were relatively rapid for vegetative forage (> or =0.086 h(-1)) but declined rapidly by the heading stage of development and stabilized thereafter. Forage quality declined and forages were more resistant to ruminal degradation as plants entered the reproductive stages of growth. Based on these findings, growth stage is an effective predictor of most characteristics of in situ DM and NDF disappearance. The relationships between these degradation parameters and growth stage were typically explained with quadratic or cubic models. Clearly, forage quality characteristics of overseeded rye deteriorated more rapidly with phenological development and growth stage than quality characteristics of overseeded wheat and oat grown in the same environment. For rye, this problem is further complicated by its accelerated phenological development. These factors combine to permit a very narrow harvest window in early spring, relative to the other cereal grains evaluated. Acceptable forage quality may persist for an extended period in wheat and oat; this suggests that producers wishing to utilize these forages may lengthen the harvest window by planting more than one species, either as a mixture or preferably in independent stands.

Mathematical descriptions of early stages of lactation were investigated using daily milk yields of 117 first, 78 second, 57 third, and 36 fourth lactations of 120 Holstein cows fitted by 10 models. The measure of fit was the error mean squares, which were replaced by ranks to perform an analysis of variance with lactation number, model, and period as factors and with cows as replicates. The interaction of model and lactation number was significant for the fit of the entire lactation. A significant interaction of model and period was obtained for the fit of three 30-d intervals. For the entire lactation, the best fit for all four lactations occurred from the diphasic logistic function, y = d1(1-tanh2(b1(nk-c1))) + d2(1-tanh2(b2(n-c2))). For the first 30 d, a modified gamma function gave the best fit for the first lactation, the inverse polynomial function for the second lactation, and the quadratic log function for the third lactation. The diphasic logistic function gave the best fit for the remaining two periods and was not significantly different from the best fitting models for the first 30-d period. Hence, this function may be useful to describe the lactation curve of Holstein cows for dairy herds in which the daily milk yield of individual cows is constantly monitored with a computer.

Forty-six broiler houses were examined for the presence of oocysts of Eimeria in the litter before and after withdrawal of lasalocid or salinomycin from the feed. A decrease in number of small oocysts (Eimeria acervulina or Eimeria mitis) was observed following withdrawal of medication. Numbers of medium-sized oocysts (probably Eimeria tenella) remained the same, but an increase in large oocysts (Eimeria maxima) was recorded. No lesions attributable to Eimeria tenella were found in the ceca of birds after withdrawal of the drug. More small- and medium-sized oocysts were found at sites with new litter than at sites where the litter had been employed for previous flocks. No difference in the number of oocysts was found, whether birds were reared on oak shavings or a mixture of pine shavings and rice hulls. The number of oocysts was positively correlated with the moisture content of the litter, but there was no correlation between oocysts present and the final BW or feed conversion of the birds. Moisture levels were highest (after withdrawal of drug) for new litter or oak shavings. There was no correlation between moisture content of the litter and BW or feed conversion.

Variances and covariances for birth weight, gain from birth to weaning (ADG), and 205-d weight were obtained from a sire-dam model and a sire-maternal grandsire model for a herd of Angus and a herd of Hereford cattle. Estimates of direct additive genetic variance (sigma 2A), maternal additive genetic variance (sigma 2M), covariance between direct and maternal additive genetic effects (sigma AM), permanent environmental variance (sigma 2PE), and residual variance (sigma 2e) were obtained both with and without the inverse of the numerator relationship matrix (A-1) included. Estimates of heritability for direct genetic effects (h2A), maternal genetic effects (h2M), and the correlation between direct and maternal effects (rAM) for birth weight were .37, .18, and -.01 in Angus and .53, .23, and -.19 in Herefords, respectively, for the analyses without A-1. For the analyses with A-1, estimates of h2A, h2M, and rAM were .42, .22, and -.12 for Angus and .58, .22, and -.13 for Herefords, respectively. Estimates of h2A, h2M, and rAM for ADG were .43, .15, and -.44 in Angus and .52, .38, and -.03 in Herefords, respectively, without A-1. With A-1, estimates of h2A, h2M, and rAM were .57, .15, and -.32 for Angus and .58, .39, and -.05 for Herefords, respectively. Estimates of h2A, h2M, and rAM for 205-d weight were .49, .15, and -.46 for Angus and .58, .43, and -.06 for Herefords, respectively, without A-1. With A-1, estimates of h2A, h2M, and rAM were .63, .16, and -.36 for Angus and .66, .43, and -.08 for Herefords, respectively. Estimates of h2A were higher with A-1 than without A-1, but estimates of h2M were similar. Using variances and covariances obtained from analyses including A-1 generally gave higher estimates of direct breeding values than using variances and covariances obtained from analyses not including A-1. Both Pearson product-moment and Spearman rank correlations were high (.99) between estimates of breeding values from the two analyses, although some changes in rank did occur.

This study determined the effects of adding a small amount of dried molasses to supplemental corn and of supplementing with corn, wheat middlings, or corn-wheat middlings mixture on intake and digestion by Holstein steers fed warn or cool season grass hays. Eight steers (175 kg BW), in two simultaneous Latin squares, were fed, once daily, bermuda-grass (72% NDF) or ryegrass-wheat (58% NDF) hay ad libitum, alone or with approximately .05% BW of dried molasses (with 31% roughage), 5% BW of ground corn, or both. Adding dried molasses to corn decreased feed intake but did not affect digestible OM intake. Total tract digestion of fiber from bermudagrass tended to be enhanced by adding dried molasses to corn. Eight steers (193 kg BW) were used in an experiment with the same design in which similar forages were fed alone or with corn (.5% BW), wheat middlings (.63% BW), or .25% BW of corn plus .31% BW of middlings. Feed intake for both grasses was similar among supplements. Wheat middlings depressed total tract fiber digestion more than corn with both forages. Supplementation with corn depressed fiber digestion slightly more with ryegrass-wheat than with bermudagrass, but wheat middlings had a slightly greater depressing effect on fiber digestion with bermudagrass. Associative effects of mixing corn and wheat middlings in OM digestion and digestible OM intake were negative for bermudagrass and positive for ryegrass-wheat. Interaction among characteristics of basal forage and concentrate modulated feed intake and digestion by ruminants.

Experiments were conducted to determine the effect of various dietary levels of Ca and P on growth and leg abnormalities in broiler cockerels fed corn and soybean meal diets varying in Ca and P content. Experiment 1 was a 2 x 4 factorial arrangement utilizing .77 and .97% Ca and .33, .38, .43, and .48% available (non-phytate) P (AP). The higher level of Ca reduced the growth rate of chicks fed low levels of AP. Neither Ca nor AP affected the incidence of crooked legs or dyschondroplasia. Increasing AP to .43% increased (P less than .05) the percentage of bone ash and bone weight. In Experiment 2, chicks were reared for 3 wk on diets containing either .40 or .50% AP. From 3 to 6 wk of age, the chicks were fed diets containing from .25 to .50% AP. The Ca:AP ratios were 2:1 in all diets. The level of AP in diets fed to 3 wk of age had no influence on chick growth, the incidence of crooked legs, or dyschondroplasia in either the starting or growing period. In Experiment 3, the chicks were reared in environmental chambers and from 3 to 6 wk of age and exposed to either constant temperature (27 C) and relative humidity (RH) (50%) or cyclic temperature (27 to 38 C) and RH (80 to 50%). The chicks were fed diets containing either .30% AP and .60% CA or .45% AP and .90% Ca from 3 to 6 wk of age. Cyclic temperature and higher RH depressed growth (P less than .05) but had no effect on the incidence of weak legs or dyschondroplasia.

Two experiments were conducted to determine the relative biological values (BV) of phosphorus in feed phosphates. Experiment 2 was a replicate of Experiment 1, except that an additional phosphate source was tested. Within experiments, each treatment was replicated twice. Each pen contained eight broiler cockerels. The experimental diets were composed primarily of corn and soybean meal. The reference phosphate [anhydrous, reagent-grade, dibasic calcium phosphate (AR-DCP)] was added to supply five levels of phosphorus. Each phosphate supplement was added to supply two levels of phosphorus. A regression equation was calculated based on logarithm g, nonphytate phosphorus per kilogram of diet versus the percentage of bone ash from chicks fed diets containing AR-DCP. Nonphytate phosphorus equivalents were calculated using the percentage of bone ash from chicks fed the test phosphates. The biological values of the test phosphates were determined as nonphytate phosphorus equivalents, minus the nonphytate phosphorus in the basal diet, divided by the amount of supplemental phosphorus. The BV obtained for the commercial phosphates in Experiments 1 and 2 were: dibasic calcium phosphate, 106 and 104; monobasic calcium phosphate. 102 and 104; defluorinated phosphate (DFP)-1, 88 and 90; and DFP-2, 100.

Unaffected chicks (normal) and chicks with pale bird syndrome (pale) were fed a control diet or a test diet obtained from the broiler house containing the pale chicks. Pale birds digested less (P less than 0.05) dry matter and ether extract than normal chicks, and the nitrogen content in their feces was greater. The chicks from both sources digested more (P less than 0.05) dry matter from the test feed but also excreted more (P less than 0.05) nitrogen than those fed the control diet. Neither diet resulted in differences in the digestion of ether extract. The cause of pale bird syndrome was related more to source of chicks rather than source of feed. Depigmentation may have resulted from decreased pigment absorption because of reduced absorption of dietary components, including ether extract.

A study was conducted to determine if the dietary need of the broiler chick for available phosphorus remained in constant ratio to the energy content of the diet. Corn-soybean meal diets were prepared with dietary energy levels of 2970, 3190 and 3410 M.E. kcal./kg. with inorganic P levels from 0.13 to 0.63% in increments of 0.10%. Least squares analyses were used to determine points of maximum response for body weight tibia ash, and efficiency of feed utilization through 28 days of age. Small but consistent reductions were observed in available phosphorus energy ratios as the dietary energy level increased. For maximum response chicks needed the following levels of inorganic phosphorus per 1000 M.E. kcal./kg. at 2970, 3190 and 3410 M.E. kcal./kg., respectively: (a) for body weight, 0.159, 0.153, 0.144%; (b) for tibia ash, 0.170, 0.168, 0.151%; (c) for feed utilization, 0.153, 0.145, 0.138%.

Male broiler chicks, from day-old to 3 weeks of age, were fed diets containing 0, 100, 220, 330, and 440 ppm citrinin produced by Penicillium lanosum grown on whole corn. Body weight decreased (P less than .05) when chicks were fed the diets containing 330 and 440 ppm citrinin. Average body weight of chicks fed the diet containing 220 ppm citrinin was 8% less than that of chicks fed no toxin. Feed utilization decreased (P less than .05) with chicks fed the diet containing 440 ppm citrinin. Analysis of thigh muscle, kidney, liver, and blood for citrinin revealed detectable amounts in the liver and blood of chicks fed 440 ppm.

The influence of temperature and propionic acid on mold growth and toxin production on whole corn with 10, 15, or 20% added water was studied. Levels of propionic acid tested at each moisture level were 0, .025, .05, and .1%. Each flask of corn was inoculated with spores of a citrinin-producing Penicillium spp. and was then incubated for 8 weeks at a constant temperature of 5 C, at 5 C at night and room temperature during the day, or at room temperature both at night and during the day. The corn was then dried, ground, and fed to chicks to determine the presence of citrinin. Regardless of acid level or moisture content, neither mold growth nor toxin production occurred on the corn incubated at 5 C. Both mold growth and toxin production occurred on corn either partially or totally incubated at room temperature but were more prevalent in the latter. Increasing the moisture content resulted in greater mold growth and toxin production, especially on the corn incubated at room temperature. Higher levels of propionic acid were needed to prevent mold growth and toxin production as the moisture content of the corn increased.

Five trials were conducted at various locations to determine the response of broiler chickens to the addition of zinc bacitracin to diets containing both salinomycin and roxarsone. Results indicate that when a combination of salinomycin and roxarsone is used as an anticoccidial, the addition of zinc bacitracin at 33 or 55 mg/kg diet will improve growth rate and feed utilization by broiler chickens. Regression of body weight and feed utilization on dietary levels of zinc bacitracin indicated that each milligram of zinc bacitracin in the diet increased the 49-day weight of broiler chickens by .92 g and reduced the feed required per gram of gain by .0012 g.

Three experiments were conducted to compare different methods of short-term potentiation of tetracycline antibiotics for broiler chicks. Reduction of dietary calcium and addition to sodium sulfate were compared in different combinations with various levels of chlortetracycline (CTC) and oxytetracycline (OTC). Reducing dietary calcium from 0.8 to 0.4% significantly increased serum levels of CTC and OTC. Adding sodium sulfate (1.25%) also increased serum levels; the majority of the response occurred at the higher calcium level. There was no benefit from adding sodium sulfate to the low-calcium diet. Neither body weight gain nor feed utilization were adversely affected during the 5-day test period.

Two experiments were conducted to determine the effects of glycerol on the quality and survival of spermatozoa in an in vitro system at 41 C in the presence of oviducal and other tissue cultures. The motility and percentages of abnormal and dead spermatozoa of glycerolized semen were significantly affected in a positive way by the presence of living cells. The most negative effect of glycerol on semen quality was observed with semen incubated in the tissue culture medium alone. Aspartate aminotransferase activity in the culture fluid revealed a harmful effect of glycerol on spermatozoa and culture cells.

Four experiments were conducted to examine the response of broiler chickens to different levels of niacin. Practical-type diets, calculated to contain from 20.7 to 23.7 mg niacin per kg from intact ingredients, were fortified with a complete vitamin mixture which provided 33 mg supplemental niacin per kg of diet, in excess of the National Research Council (1977) suggested requirement of 27 mg per kg through 6 weeks of age. A niacinamide supplement was used to provide additional levels of 0, 33, or 66 mg per kg. Diets differed in content of added fat and energy levels in two of the experiments and in the presence or absence of animal protein sources in two others. The addition of niacinamide at 33 and 66 mg per kg to a diet already supplemented with 33 mg per kg from a complete vitamin premix, calculated to exceed the present NRC suggested requirement, resulted in improved body weight gains with sex differences noted in some experiments. Feed utilization was improved in some studies. There was no effect on the amount of abdominal fat or carcass dressing percentage. The results of these studies indicate that the modern rapidly growing broiler chick may require niacin levels greater than those generally recommended by the National Research Council (1977), which are based largely on studies where performance was considerably lower than obtained with the modern strains of broilers.

Broiler cockerels were used in four trials of 3-wk duration to investigate the effects of altering dietary cation:anion ratios on chick growth, leg abnormalities, bone, and blood parameters. Dietary cation content was changed using Ca and Mg, whereas the anions P, Cl, and S were included at various levels, giving several total cation:anion ratios with several levels of ions. Narrowing the cation:anion ratios increased 3-wk body weights and the incidence of both dyschondroplasia and varus deformation. Further increases in dietary anion concentration generally caused a slight depression of body weights. Supplementation of Ca or Mg to diets containing high levels of anion relative to cation decreased the incidence of leg problems and lowered 3-wk body weights. Blood pH was not significantly affected by dietary mineral alterations, although pH tended to decrease as anion content was increased. Addition of P significantly reduced blood HCO3 and base excess (meq/L). Base excess was negatively correlated (P less than .05) with the incidence of TD and 3-wk body weights. Two strain-crosses of broiler cockerels, fed diets which had previously increased the incidence of leg abnormalities, exhibited no significant differences in the incidence of varus deformation or dyschondroplasia. The strain-cross of chicks having the lowest base excess had higher incidences of both leg disorders, although body weights were identical.

A liquid methionine supplement known as methionine hydroxy analogue-free acid (MHA-FA) was evaluated as a source of methionine in the diet of young broiler chicks. Diets calculated to be deficient in methionine were supplemented with MHA-FA and performance compared to that obtained when comparable diets were supplemented with molar equivalents of methionine from L-methionine, DL-methionine, or the calcium salt of methionine hydroxy analogue. Performance of chicks fed the test product was equal to that obtained on the other methionine products. The use of MHA-FA might allow for a more even distribution in the diet, easier handling, and a lower manufacturing cost with resultant savings in the cost of producing poultry and eggs.

A study was conducted to determine the ability of chicks to digest dry matter and amino acids and to utilize the energy from uncontaminated corn and contaminated corn containing mycotoxins. The contaminated corn contained either aflatoxin from natural molding, citrinin by artificially molding with a Penicillum spp., or ochratoxin by inoculation with Aspergillus ochraceus. Compared to uncontaminated corn, none of the criteria measured was affected in corn contaminated with aflatoxin. Dry matter digestibility, amino acid digestibility, and energy utilization were reduced (P less than .05) when corn was artificially molded with the Pencillium spp. and with A. ochraceus.

Pooled semen was diluted with Lake's solution containing 10.8% (v/v) glycerol. Aliquots of 1.2 mL and .5 mL were transferred to 1.8-mL capacity plastic vials and .5-mL capacity plastic straws, respectively. Semen was processed at 5 C, frozen by cooling at a rate of 3 C/min to -35 C, then plunged in liquid nitrogen. Samples were thawed at 5 C, diluted stepwise, centrifuged, and resuspended with nonglycerolized diluent at 5 C. Fertility and its duration were measured after single or double (insemination on 2 consecutive days) insemination. No significant differences were found in fertility percentages between semen samples frozen and stored in the two types of containers. However, fertility percentages were significantly higher for eggs laid on Days 2 to 5 after double insemination than for eggs laid after single insemination. No such differences were noted in the fertility of eggs laid on Days 2 to 7. Duration of fertility was significantly longer for semen frozen in plastic vials than for semen frozen in straws.

Feeding trials were conducted with broiler breeder hens to determine optimum daily intake of protein for maximum performance. Pullets were grown to 24 weeks of age on limited feed intake to maintain the body weight within the limits suggested by the breeder. A controlled-feeding system was used during the laying period with step-wise increase in calorie intakes. In the first study corn-soybean type diets were used to supply 14 to 22 grams of protein/day in 2 gram increments. In the second study daily protein intakes of 14.5 to 24 grams were compared. In addition, diets supplying 14.5 and 16 grams of protein daily were also fed with an additional 200 mg/day of lysine and methionine. The results of these studies suggest that the protein requirement of broiler breeder hens fed corn-soybean meal diets without supplemental amino acids is 20-22 grams per day.

The relationship between dry matter digestion (DMD) and metabolizable energy (ME) adjusted for nitrogen balance (n) and endogenous energy losses (e) was investigated in two experiments using immature broiler chicks (i). Ingredients tested were corn, wheat, oats, and soybean meal (SBM). A bioassay utilizing 21-day-old broiler chicks was carried out for determination of MEn,e,i. These values were compared with those obtained by multiplying gross energy of the feed by dry matter digestion adjusted for excreta losses from fasted birds (DMD) using regression analysis. There was a significant (P less than .0001) correlation (4 = .96) between estimated and determined MEn,e,i values for all grains and SBM. This was improved by removal of SBM from regression analysis with a decrease in the residual standard deviation from +/- .093 to +/- .036 kcal/g.

Penicillium lanosum, when grown on corn, produces a metabolite which increases water intake and excretion by chicks. During a 5-hr test period, chicks fed inoculated corn as the only feed began excreting water within 2 hr and excreted as much as 36 ml, whereas chicks fed untreated corn did not excrete measurable amounts. Chicks fed the inoculated corn drank more water than those fed untreated corn. The metabolite could not be extracted from oven-dried corn but was removed from air-dried corn which had been moistened with acid and extracted with chloroform and then with methanol. It was soluble in 1% sodium bicarbonate and precipitated as yellow cystals when the solution was acidified to pH 1.5. The precipitate was identified as citrinin based on the results of thin layer chromatography, ultraviolet, infrared, mass spectrometer, fluorescence excitation and emission, and nuclear magnetic resonance spectra.

Chicks, 30 days old, were fed a corn-soybean meal diet containing different concentrations of cation and anion to determine the effect of acid-base balance on the digestion of dry matter and amino acids and on energy utilization. The concentrations of cation and anion were altered by varying the levels of calcium and phosphorus in the diet. Excess cation (cation minus anion) was negatively correlated (P less than .01) to dry matter digestion, amino acid digestion, and nitrogen-corrected metabolizable energy (MEn) content of the diet. The digestion of the individual amino acids was also affected by excess cation in the diet.

Six trials were conducted at different locations to examine the response of broiler chickens to roxarsone and bacitracin in the form of bacitracin methylene disalicylate (BMD) in the presence of the anticoccidal narasin. All diets contained narasin (80 mg/kg) and were fortified with a factorial arrangement of roxarsone (0 to 50 mg/kg) and BMD (0 or 55 mg/kg). Broilers were grown to market weights with narasin and roxarsone removed from the diets for the final 5 days. Addition of both roxarsone and BMD resulted in significant (P less than .05) improvements in body weight and feed utilization. Response to roxarsone for feed utilization was influenced to some extent by the presence or absence of BMD. Although the response to roxarsone was always positive, the degree of response was lessened by the presence of BMD. This resulted in a significant (P less than .10) interaction between roxarsone and BMD for feed utilization but not for body weight.

Sterilized whole corn was inoculated with a Penicillium spp.,3 a citrinin-producing fungus, and incubated at room temperature for 8 weeks. The corn was then blended and divided into two parts, which were dried either in air at room temperature (ADC) or in a forced draft oven at 60 C for 24 hr (ODC). Each batch of corn was ground and stored in plastic containers. The corn was fed to broiler chicks prior to and after 3, 6, 9, and 12 months of storage at 4 C. The inoculated corn was fed undiluted or blended with noninoculated corn to give mixtures containing one-third and two-thirds of inoculated corn. Noninoculated corn, inoculated corn, and blends of the two were fed to chicks for 5 hr as the only feed. Feed consumption, water intake, and excretion were measured at the end of the test. The citrinin contents of the ADC at 3, 6, 9, and 12 mo were 824, 599, 667, and 590 ppm and were 928, 541, 781, and 490 ppm for the ODC at the same periods. Water consumption and water excretion increased as the amount of citrinin intake increased. Neither drying method nor length of storage affected the citrinin activity in the corn. The citrinin in ODC was neither bound nor converted to a derivative that was unextractable.

Two experiments were conducted to evaluate the response of broiler chickens to addition of bacitracin methylene disalicylate (BMD) to diets containing salinomycin. In each experiment, five tests were conducted at different locations. In Experiment 1, all diets contained 66 mg salinomycin/kg of diet for the first 42 days and either 0 or 33 mg BMD/kg of diet for the entire 49-day feeding period. In Experiment 2, all diets contained 66 mg salinomycin and 50 mg roxarsone/kg of diet for the first 42 days and either 0, 11, 33, or 55 mg BMD/kg of diet for the entire 49-day feeding period. In Experiment 1, addition of 33 mg BMD/kg of diet significantly (P less than .05) improved body weights and feed utilization. Results were similar in all five tests. In Experiment 2, addition of 11, 33, or 55 mg BMD/kg of diet significantly (P less than .05) increased body weights. In one location the addition of 55 mg BMD/kg of diet resulted in no significant difference in body weight compared with those fed the unsupplemented diet, but in all other locations the response was similar. Addition of 33 or 55 mg BMD/kg of diet resulted in improved (P less than .05) feed utilization when all tests were combined. Feed utilization was not improved in all locations by the addition of BMD.

Studies were conducted at six locations over a 7-yr period to evaluate the response of broiler chickens to bacitracin methylene disalicylate (BMD) and roxarsone in the presence of diets containing 3 ppm halofuginone/kg feed. Treatments consisted of a 2 x 2 factorial arrangement with 0 or 55 mg BMD and 0 or 50 mg roxarsone/kg feed. These additives were fed beginning with day-old chicks and were removed 6 days before termination of the study, which varied in length from 48 to 56 days among locations. Body weights were significantly improved (P less than .05) by the addition of either BMD or roxarsone with a significant interaction (P less than .05) between BMD and roxarsone. Roxarsone improved body weights only in the presence of BMD. Feed utilization was significantly (P less than .05) improved by addition of either BMD or roxarsone, with no interaction between the two products.

Experiments were conducted to determine if drying citrinin-contaminated corn at varying temperatures and times either bound citrinin or converted it to a derivative that could not be extracted from the grain. Sterilized whole corn was inoculated with spores of a Penicillium spp. that produces citrinin and was incubated for 8 weeks. Following incubation, the corn was mixed and divided into three portions. In Experiment 1, one portion was dried at room temperature and the other portions were dried at 65 C for either 40 or 72 hr. In Experiment 2, one portion was air-dried and the other portions were dried at 60 C for 24 hr or 100 C for 3 hr. The corn was then ground to a texture suitable for feeding to chicks. Analysis of the corn indicated that temperature or length of drying time had no adverse effects on the extraction of citrinin from the corn. The citrinin was not rendered unextractable by either being bound because of heating or by being converted to a derivative. When fed to chicks for 5 hr, water consumption and urine excretion data indicated that there was no loss of citrinin activity because of method of drying.