Effect of age of maternal flock and strain on the incidence of tibial dyschondroplasia in growing chicks.

Two experiments were conducted to study the effects of age of the maternal flock (27 vs. 57 weeks of age at time the eggs were set) and strain of broiler chicks (Cobb 500, Ross, Arbor Acres, and Avian) on the incidence of tibial dyschondroplasia (TD) in broiler cockerels grown to 3 weeks of age. The chicks were fed a corn/soybean meal-based diet containing 3145 kcal metabolizable energy corrected for nitrogen retention (MEn)/kg, 24% protein, and 0.50% available phosphorus. Each treatment was replicated four times with eight chicks per pen. In Expt. 1, chicks from the old parent flock had significantly higher body weights (P < or = 0.05) than those from the young parent flock. There were no significant differences in feed efficiency or incidence of TD. In Expt. 2, body weights, feed efficiency, and TD were unaffected by strain.

Effect of calcium and phosphorus on the incidence of leg abnormalities in growing broilers.

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.

The relative biological value of feed phosphates for chicks.

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.

Effect of altering dietary mineral balance on growth, leg abnormalities, and blood base excess in broiler chicks.

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.

Citrinin toxicity in young chicks.

Two experiments were conducted to demonstrate the capacity of citrinin to cause dose-related increases in water consumption and urine excretion. In Experiment 1, chicks 24 days old were fed mixtures of untreated and inoculated corn containing citrinin to provide 0, 50, 100, 150, 200, and 250 micrograms of the toxin per gram of blended corn. The corn was fed for 4 hr, and water intake and urine excretion were measured. Chicks consumed 0, 1.23, 2.37, 3.68, 4.26 and 5.44 mg citrinin from the respective treatments. Compared with chicks consuming no citrinin, water intake and urine excretion of treated chicks increased (P less than .05) when chicks consumed 3.68 mg or more citrinin. Measures of the difference between water intake and urine excretion were similar for all treatments except for chicks consuming 3.68 mg citrinin; for those chicks the difference was significantly greater (P less than .05) than for chicks consuming 1.23 mg citrinin. In Experiment 2, inoculated corn was heated in a microwave oven for 1, 2, 8, and 16 min. Temperatures of the heated corn samples, when removed from the oven, were 76 C, 100 C and 105 C, respectively. Chicks that were 28 days old were fed these various samples of corn for 4 hr. Heating corn for 2 min to a temperature of 76 C caused no apparent loss of citrinin activity based on water intake and urine excretion measures. Heating the corn for 8 min to a temperature of 100 C destroyed some of the citrinin activity. Heating citrinin-contaminated corn to 105 C for 16 min destroyed the diuretic effect of the mycotoxin.

Relationship between dry matter digestion and metabolizable energy.

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.

Effect of heat drying of corn on the extraction of citrinin.

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.

The effect of drying method and storage time on citrinin activity in corn.

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.

Effect of fiber and phytate source and of calcium and phosphorus level on phytate hydrolysis in the chick.

Broiler chicks were fed a corn-soybean meal diet or a corn-soybean meal diet containing either 15% rice bran, 15% wheat bran, 15% alfalfa meal, 10% cellulose, or 10% cottonseed hulls. All diets contained 3190 kcal/kg of metabolizable energy, 22.8% protein, and either 1.0% calcium and .5% nonphytate phosphorus (Pnp) or .85% calcium and .42% Pnp. The diets were fed for 3 weeks at which time a digestion trial was conducted to determine the amount of phytate hydrolyzed. Chicks consuming diets containing the lower levels of calcium and Pnp hydrolyzed more phytate than those fed the higher levels of calcium and Pnp except when the diet contained rice bran. Less phytate was hydrolyzed in the rice bran diet at the lower calcium and Pnp levels. Phytate hydrolysis was not affected by wheat bran but was reduced by cottonseed hulls. At the lower levels of calcium and Pnp, alfalfa meal and cellulose significantly increased phytate hydrolysis by chicks. The hydrolysis of phytate was influenced more by calcium and by source than by fiber or by level of phytate fed.

Influence of temperature, moisture, and propionic acid on mold growth and toxin production on corn.

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.

Digestion of feed by chicks with pale bird syndrome.

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.

Digestion of dry matter and amino acids and energy utilization by chicks fed molded corn containing mycotoxins.

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.

Citrinin toxicity in growing chicks.

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 effect of altering the cation-anion content with calcium and phosphorus on the digestion of dry matter and amino acids and on energy utilization.

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.

Isolation and identification of citrinin produced by Penicillium lanosum.

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.