Effects of a monocomponent protease on performance and protein utilization in 7- to 22-day-old broiler chickens.

A study was conducted with an exogenous monocomponent protease added to corn-soybean meal diets fed to straight-run Ross 708 broilers from 7 to 22 d of age. Broilers were randomly placed into 42 battery pens (5 birds/pen) and allocated to 6 treatments with 7 replicates. A positive control diet (PC; 22.5% CP) and a low protein basal diet (20.5% CP) were formulated. Low protein diets (LP) comprised 98.67% of low protein basal diet and 1.33% Celite (indigestible marker and filler; Celite Corp., Lompoc, CA). Protease [75,000 PROT units/g; 1 PROT unit is defined as the amount of enzyme that releases 1 µmol of p-nitroaniline from 1 µM of substrate (Suc-Ala-Ala-Pro-Phe-p-nitroaniline per minute at pH 9.0 and 37°C] was added at the expense of Celite (0 mg/kg, LP0; 100 mg/kg, LP100; 200 mg/kg, LP200; 400 mg/kg, LP400; and 800 mg/kg, LP800) to create the LP diets (20.25% CP). At 22 d of age, ileal contents were collected from all birds for apparent CP and amino acid (AA) digestibility determinations. Broilers fed the PC diet were 7.5% heavier (P < 0.05) compared with those fed the LP0 diet. Birds fed the LP diets containing protease regardless of concentration grew as well as the birds fed the PC diet. Feed conversion was impaired (P < 0.05) in birds fed the LP0 and the LP100 diets compared with those fed the PC diet, but no difference was found between birds fed the PC diet and those fed diets containing more protease (LP200, LP400, and LP800). Digestibility of CP was increased (P < 0.05) in broilers fed the LP-supplemented diets compared with those fed either the PC or LP0 diets, but it was similar between those fed LP diets with any protease concentration. Digestibility of AA was not different between the PC and LP0 diets. The protease used in this study restored live performance and digestibility of CP (6.1%). When benefits in AA digestibility occurred, they were similar at all protease inclusions and averaged as follows: Arg, 3.5%; Ile, 3.2%; Lys, 5.4%; Thr, 7.8%; Asp, 6.5%; His, 3.3%; Cys, 4.6%; and Ser, 5.5%. Methionine was increased only at 400 and 800 mg/kg (6.5%) and Val was increased only at 200 and 800 mg/kg (5%).

Comparison of a modern broiler line and a heritage line unselected since the 1950s.

Selecting chicken for improved meat production has altered the relative growth of organs in modern broiler lines compared with heritage lines. In this study, we compared the growth and feed efficiency of a heritage line, UIUC, with a modern production line, Ross 708, for 5 wk posthatch. During this period, the BW and feed efficiency of the modern strain was higher than that of the heritage line, indicating that the Ross 708 birds were more efficient than the UIUC birds at converting feed to body mass. The relative growth of the breast, heart, liver, and intestine were also compared during these 5 wk. The breast muscle of the heritage line constituted 9% of the total body mass at 5 wk, whereas in the modern line, the breast muscle was 18% of the total mass of the bird. In contrast, the relative size of the heart decreased after d 14 in the modern line, suggesting that selection for increased breast muscle has translated into relatively less weight of the heart muscle. The liver matured earlier in modern lines, possibly improving nutrient utilization as the birds shift from lipid- to carbohydrate-rich feed. Finally, jejunal and ileal sections of the intestine were 20% longer in the modern line, perhaps allowing for increased nutrient absorption.

Effect of dietary phosphorus, phytase, and 25-hydroxycholecalciferol on broiler chicken bone mineralization, litter phosphorus, and processing yields.

Three floor pen experiments (Exp) were conducted to evaluate low nonphytin P (NPP) concentrations and the NPP sparing effect of phytase (PHY) and 25-hydroxycholecalciferol (25D) on bone mineralization, bone breaking during commercial processing, litter P, and water-soluble P (WSP) concentrations. Tested treatments (TRT) were control, National Research Council NPP; University of Maryland (UMD) NPP; UMD + PHY, UMD NPP reduced by 0.064% NPP + 600 U of PHY/kg; UMD + PHY + 25D, UMD NPP reduced by 0.090% NPP + 600 U of PHY and 70 microg of 25D/kg; control + PHY mimicked the industry practice of diets by 0.1% when PHY is added; and negative control with 90% UMD NPP concentrations. UMD + PHY and control + PHY diets contained 600 U of PHY/kg, and UMD + PHY + 25D contained 600 U of PHY + 70 microg of 25D/kg. Performance results were presented separately. After each Exp, litter P and WSP were determined, and bone measurements were obtained on 8 or 10 broilers per pen. Tested TRT did not affect broiler BW. Femur ash weight of broilers fed the UMD and UMD + PHY + 25D was lower in all Exp compared with that of broilers fed the control diet. Femur ash was similar for control and UMD + PHY broilers, yet averaged over all Exp, UMD + PHY broilers consumed 39% less NPP and required less NPP per gram of femur ash than those on the control (4.87 and 7.77 g of NPP/g of ash, Exp 3). At the end of Exp 3, broilers were processed in a commercial facility. Despite reductions in NPP intake and bone mineralization, no differences were observed in measurements of economic importance (parts lost, carcass yield, and incidence of broken bones). The P excretion per bird was lowest for birds fed the UMD + PHY + 25D diet followed by those fed the UMD + PHY and negative control diets (10.44, 12.00, and 13.78 g of P/bird, respectively) and were highest for those fed the control diet (19.55 g of P/bird). These results suggest that feeding diets low in P together with PHY and 25D will not affect performance or increase losses at processing while resulting in improved P retention and reductions in P and WSP excreted.

Effects of dietary phosphorus, phytase, and 25-hydroxycholecalciferol on performance of broiler chickens grown in floor pens.

Three 49-d experiments (Exp 1, 2, and 3) with broilers in floor pens were conducted to test the applicability of nonphytin phosphorus (NPP) requirements and the NPP-sparing effect of phytase (PHY) and 25-hydroxycholecalciferol (25D) determined previously in battery Exp. Six dietary NPP treatments were tested using a 4-phase feeding program. Treatments 1 to 6 were NRC (1994) NPP (C); University of Maryland (UMD) NPP; UMD NPP - 0.064% (UMD+PHY); UMD NPP - 0.09% (UMD+PHY+25D); NRC - 0.10% (C+PHY), and 90% UMD NPP (NC), respectively. Treatments 3, 4, and 5 had 600 U of PHY/kg of diet. Treatment 4 also had 70 microg of 25D/kg of diet; NPP concentrations were reduced to account for the sparing effect of these additives. No differences in hatch to 49 d BW were observed between treatments in Exp 1 and 2, and only in Exp 3 were the BW of the NC broilers (2.86 kg) different (P < 0.05) from those fed the C, UMD, and UMD+PHY treatments (2.96, 2.94, and 2.98 kg, respectively). Cumulative NPP consumption per bird was lowest (P < 0.05) for broilers fed the UMD+PHY+25D treatment (8.65 g in Exp 3) compared with those fed the C, NC, UMD, and UMD+PHY treatments (18.19, 10.60, 13.63, and 11.01 g, respectively for Exp 3). Application of any of these treatments reduced total P and NPP consumption compared with C. The results of this series of floor pen Exp validate the UMD NPP recommendations for a 4-phase feed program and the PHY and 25D NPP-sparing effects observed in battery trials without negatively affecting broiler performance.

Influence of phytase addition to poultry diets on phosphorus forms and solubility in litters and amended soils.

Diet modification to decrease phosphorus (P) concentration in animal feeds and manures can reduce surpluses of manure P in areas of intensive animal production. We generated turkey and broiler litters from two and three flock trials, respectively, using diets that ranged from "high" to "low" in non-phytate phosphorus (NPP) and some of which contained feed additives such as phytase. Phosphorus forms in selected litters were analyzed by sequential chemical fractionation and solution (31)P nuclear magnetic resonance (NMR) spectroscopy. Selected litters were also incubated with four contrasting soils. Reducing dietary NPP and using phytase decreased total P in litters by up to 38%. Water-soluble phosphorus (WSP) in litters was decreased 21 to 44% by feeding NPP closer to animal requirement, but was not affected by phytase addition. Solution (31)P NMR spectroscopy showed that feeding NPP closer to requirement decreased orthophosphate in litters by an average of 38% and that adding phytase to feed did not increase the concentration of orthophosphate in litters. Phytase also decreased phytate P in litters by 25 to 38%, demonstrating that it increases phytate P hydrolysis. Incorporation of litters with soils at the same total P rate increased WSP in soils relative to the control; this increase was correlated to soluble P added with litters at 5 d, but not by 29 d. Changes in soil Mehlich-3 phosphorus (M3-P) were related to total P added in litter, rather than soluble P. We conclude that feeding NPP closer to requirement and using feed additives such as phytase decrease total P concentrations in litters, while having little effect on P solubility in litters and amended soils.

Alternative solutions to the problem of selection bias in an analysis of federal residential drug treatment programs.

In an evaluation of prison-based residential drug treatment programs, the authors use three different regression-based approaches to estimating treatment effects. Two of the approaches, the instrumental variable and the Heckman approach, attempt to minimize selection bias as an explanation for treatment outcomes. Estimates from these approaches are compared with estimates from a regression in which treatment is represented by a dummy variable. The article discusses the advantage of using more than one method to increase confidence in findings when possible selection bias is a concern. Three-year outcome data for 2,315 federal inmates are used in analyses where the authors separately examine criminal recidivism and relapse to drug use for men and women. Statistical tests lead the authors to conclude that treatment reduces criminal recidivism and relapse to drug use. The treatment effect was largest when the inference was based on the Heckman approach, somewhat smaller when based on the instrumental variable approach, and smallest when based on the traditional dummy variable approach. Treatment effects for females were not statistically significant.

Federal prison residential drug treatment reduces substance use and arrests after release.

OBJECTIVE: The effectiveness of federal prison-based residential drug and alcohol treatment programs was evaluated using event history procedures that addressed the problem of selection bias and included a wide range of control variables. METHODS: The sample comprised 760 treatment subjects and 809 comparison subjects. Treatment subjects were from 20 different prisons of medium, low, and minimum security levels. Comparison subjects were drawn from over 30 prisons. RESULTS: The results indicated that individuals who entered and completed in-prison residential treatment were less likely to experience the critical postrelease outcomes of new arrests and substance use during the first 6 months following release. CONCLUSIONS: Without controlling for selection bias, the effects of treatment would most likely have been attenuated. The results have greater generalizability than other studies of prison-based treatment. This study occurred within a multisite context of 20 programs serving both male and female inmates and operating within different security levels and different geographic regions.

Folate metabolism and deposition in eggs by laying hens.

White Leghorn hens were fed purified folate-deficient diets or commercial corn- and soybean meal-based diets supplemented with different amounts of folic acid. The folate contents of egg yolk and blood plasma from these hens were estimated with an isotope-dilution, radioligand-binding assay. Folates in egg yolk were concentrated approximately 43-fold relative to the blood plasma from which they were derived. Yolk and plasma folate concentrations became saturated with increasing dietary folate. Hens fed a commercial, folate-sufficient diet (0.72 mg folate/kg) produced eggs with slightly less than half of the maximal folate content. Based on tritium deposition in egg yolk and egg white, the biological half-life of [3H]folic acid injected intraperitoneally into two folate-sufficient hens was approximately 15 days, while it was > or = 40 days in two hens fed a purified folate-deficient diet (0.07 mg folate/kg) that also reduced egg production. Radioactivity in egg yolk was concentrated more than 100-fold relative to egg white in both cases. The [3H]folates remaining in the hens at the end of the experiment were substantially more concentrated in liver than in kidney, heart, or skeletal muscle. The specific radioactivity of folates in the liver of folate-deficient hens after 78 days was almost 10 times greater than in folate-sufficient hens after 39 days. Laying hens have highly efficient conservation and delivery systems for folates.

Effect of riboflavin-binding protein deficiency on riboflavin metabolism in the laying hen.

Normal chicken eggs contain substantial amounts of riboflavin, all of which is bound to a specific, high-affinity, riboflavin-binding protein (RfBP). Two hens, genetically unable to produce RfBP and thus unable to deposit sufficient riboflavin in their eggs, were compared to two normal hens with respect to the biological half-life of [14C]riboflavin, the tissue distribution of 14C-labeled flavins, and the relative contributions of tissue and dietary riboflavin to flavins deposited in the egg. The biological half-life of [14C]riboflavin was slightly but insignificantly less in the RfBP-deficient hens (11.5 +/- 1.7 days vs 15.1 +/- 3.3 days). The 14C-labeled flavin content of a variety of tissues 3 weeks after the intraperitoneal injection of 5 microCi of riboflavin was also very similar among the four hens. In contrast, the 14C-labeled flavin content of egg yolk, egg albumen, and blood plasma from RfBP-deficient birds was less than 10% of normal. For all hens, the specific radioactivity of flavins in yolk and albumen was similar to that in liver but less than that in heart. We conclude that riboflavin deposited in egg had equilibrated with the large hepatic flavin pool and was not derived preferentially from unlabeled dietary riboflavin. Other than the inability to deposit riboflavin in their eggs, hens of the mutant strain have normal riboflavin metabolism.

The Pediatric Early Elementary Examination: sensitivity and specificity.

Evaluated the sensitivity and specificity of the Pediatric Early Elementary Examination (PEEX), a test designed to identify children at risk for learning problems. Using a sample of 299 seven- to nine-year-old "disadvantaged" children, the number of "areas of concern" identified by the PEEX and a school record indicating whether a child was receiving special educational services were used to compute test sensitivity and specificity. For two areas of concern, the sensitivity was 76.9% and specificity was 59.9%. The findings indicate that the PEEX correctly identified only 64.3% of children receiving special educational services. The test has a high rate of false positives while still failing to identify 6-7.5% of the children receiving special education services. Other issues relating to the utility of the PEEX are discussed.

Intracellular distribution of copper and zinc in sheep: effect of age and dietary levels of the metals.

This study was conducted to assess the effects of age and dietary levels of copper and zinc on the intracellular distribution of these metals in sheep, the domestic species most susceptible to copper toxicity. Hepatic copper concentration was lower in newborn lambs than in 30- and 60-day old lambs and its distribution in neonates differed significantly from that in the older animals and from that observed in newborn and adult rats. Sheep previously maintained on a low-copper diet for 50 days were then fed diets containing 2.2, 11.3 or 47.0 microgram Cu/g diet with and without zinc supplementation (543 or 46 microgram Zn/g diet, respectively) for 60 days. Ceruloplasmin activity, total plasma copper and hematocrit were lower in zinc-supplemented sheep. Hepatic copper concentration was not reduced by zinc supplementation but was increased with each increase in dietary copper; the distribution pattern was significantly altered as hepatic copper increased. Hepatic zinc concentration and distribution were not affected by diet. Sheep fed the highest level of copper had higher copper concentrations in the mucosa of the small intestine and in kidney cortex. The concentrations of zinc in the kidney and of copper and zinc in diaphragm muscle and bile were not affected by diet.

Copper- and zinc-binding proteins in sheep liver and intestine: effects of dietary levels of the metals.

Liver cytosol from sheep fed diets containing 2.2, 11.3 or 47 microgram Cu/g diet with or without supplemental zinc (543 or 46 microgram Zn/g diet), fractionated on Sephadex G-100, yielded three main copper- and zinc-containing proteins with approximate molecular weights of greater than 150,000, 27,000 and 10,000. Amino acid analysis of the 10,000-molecular-weight proteins were of the metallothionein type. Copper-chelatin was not present in sheep liver cytosol. Copper concentration of the metallothionein fraction increased (P less than 0.01) as dietary copper increased from 2.2 to 11.3 microgram Cu/g, but did not increase further when dietary copper increased to 47 microgram Cu/g in unsupplemented sheep. A low-molecular-weight (approximately 3,500) copper-, but not zinc-containing fraction appeared at this highest level of copper. Zinc supplementation of the diet increased not only the zinc content of the metallothionein fraction but also its copper content, most dramatically in sheep fed the highest copper level. In intestinal mucosal cytosol, no copper and little zinc was associated with the metallothionetin fraction which was not affected by dietary treatment. Evidence from this study suggests that sheep have limited capacity to synthesize metallothionein in response to increased dietary copper.

A simple device for efficient transfer and unit dose packaging of Xe-127: concise communication.

An inexpensive system has been devised for the efficient transfer of Xe-127 gas from the manufacturer's ampule into individual dose vials for patient use. By displacing the gas with an aqueous solution, the initial transfer is made from an ampule of known activity into an evacuated serum vial of predetermined volume with transfer efficiency greater than 99%. A similar principle is used to transfer Xe-127 from the stock serum vial into individual dose vials, with total xenon recovery exceeding 98%. Ability to deliver the desired activity to each vial is within 90-110% of that predicted by calculation. Reproducibility in delivering a given activity was excellent, with all vials falling between 95 and 105% of the mean activity. Stability studies showed that 94% of the Xe-127 activity can be removed from the vials with only 6% absorbed in the rubber stopper after 5 wk of storage. The device costs less than $25.00 and can be constructed easily from common laboratory materials.

Dosimetry of 137Cs sources with the Fletcher-Suit gynecological applicator.

Measurements were made in water about the tandem and ovoid structures of the Fletcher-Suit applicator loaded with a 137Cs source. The dose rate was found to vary as much as 25% as a result of differential absorption in the ovoid. Empirically based trigonometric expressions are suggested which provide the absorption correction as a function of the two angles of a spherical coordinate system. Computer calculated dose rates, with and without the absorption corrections, are compared.

Factors affecting survival in stage I and state II carcinoma of the cervix.

Eighty-eight cases of Stage I and Stage II carcinoma of the cervix treated with radiotherapy at the University of North Carolina Memorial Hospital between April 1969 and July 1971 are reviewed. The question of whether the radiation time-dose-fraction relationship can be applied to the combination of external beam and intracavitary therapy used in the treatment of cervical carcinoma is studied. Formulas are outlined which enable one to calculate a total Rad Equivalent Therapy (RET) value, including the contribution from both the fractionated external beam and intracavitary therapy. Both the calculated RET value and the rad dose to Point A show good correlation with control of local disease in this retrospective analysis; however, the RET value may be more applicable when deviations from the standard time-dose-fraction relationship have occurred.

A new calculator for radiotherapy treatment planning.

Comparison of speed and costs of the programmable desk calculator and the minocomputer reveals that although the desk calculator is slower, most operations are simple dose and treatment time calculations in which the turn-around time is essentially immediate. Assuming a five-year equipment capitalization of the initial $24,000 cost and $1,700 per annum maintenance charge with a workload of 800 plans per year, the cost per plan is about $8.00. This does not include programmer salaries.