Estimation of factors associated with the occurrence of white striping in broiler breast fillets.

Broiler breast fillets are sometimes characterized grossly by white parallel striations in the direction of the muscle fibers, and the condition is referred to as white striping. Depending on the severity of white striping, fillets can be classified as normal (NORM), moderate (MOD), or severe (SEV). The present study was intended to determine the factors associated with the occurrence of white striping in broiler breast fillets. Broiler birds (59 to 63 d) of 4 different commercial high-yielding strains (both males and females) fed with industrial type or phase-feeding regimens, were processed and ready-to-cook carcass weight was recorded. The carcasses were deboned at either 4 or 6 h postmortem. Fillets were scored for the degree of white striping at 24 h postmortem, and dimensions of fillets (length, width, cranial thickness, and caudal thickness), pH, color (L*, a* and b* values), cook loss, and Meullenet-Owens razor shear energy (MORSE) values were determined. About 55.8% of the birds used in the study showed some degree of white striping with MOD and SEV categories as 47.5 and 8.3%, respectively. Higher degrees of white striping were significantly (P < 0.05) related to higher cranial fillet thickness and ready-to-cook weights. The occurrence of SEV degrees of white striping was accompanied with increased b* values or yellowness of the meat. The growth differences in strains could influence the incidence of this condition, but feeding regimens and chill hour during processing did not. In addition, the degree of white striping did not show any significant (P > 0.05) relationship between various meat quality parameters such as pH, L*, a*, cook loss, and MORSE. In conclusion, the results of this study suggest that there is a greater chance of higher degrees of white striping associated with heavier birds, but the condition is not related to any major changes in cooked meat quality.

Phase feeding in a big-bird production scenario: effect on growth performance, yield, and fillet dimension.

Phase feeding (PF) has been effective at maintaining broiler growth while reducing production cost, but the effect on different broiler strains and sex has not been assessed. An experiment was conducted using 4 commercial broiler strains grown up to 63 d of age (n = 1,440), comparing a PF approach to an industry-type diet. At d 17, birds began either the industry or PF regimen. The industry regimen consisted of average industry nutrient levels with periods from 17 to 32 d, 32 to 40 d, 40 to 49 d, and 49 d to the end of trial. For PF, diets were prepared that contained Lys, sulfur amino acids, and Thr levels matching the predicted requirements for birds at the beginning (high nutrient density) and end (low nutrient density) of PF. Pelleted high and low nutrient density diets were blended to produce rations containing amino acid levels that matched the predicted PF requirements over 2-d intervals. Weight gain, feed intake, and feed efficiency were calculated through d 58. Birds were commercially processed at 59, 61, or 63 d; yield and fillet dimensions were measured. Phase feeding did not effect weight gain or feed intake of broilers during the overall growth period (17-58 d). For most strains, PF did not effect final BW, yield, or fillet dimensions. However, strain and sex had greater effects on growth performance, yields, and fillet dimensions. Strains B and D had greater breast yield than strains A and C. Reduced feed costs ($0.01 to $0.04 per kilogram of gain, depending on strain) were observed for all strains with PF for the overall growth period (17-58 d). Therefore, potential savings on feed costs are possible for all strains used in this study with the incorporation of the PF regimen.

Phase feeding in a small-bird production scenario: effect on growth performance, yield, and fillet dimension.

Phase feeding (PF) has been effective at maintaining broiler growth while reducing production cost, but the effect on different broiler strains grown in a small-bird production scenario has not been assessed. Three strains of commercial broilers were fed a diet containing average industry nutrient levels from 0 to 18 d. From 18 to 32 d, birds were fed either diets with average industry nutrient levels or diets with phased levels of amino acids. For PF, diets were prepared that contained Lys, sulfur amino acids, and Thr levels matching the predicted requirements for birds at the beginning (high nutrient density) and end (low nutrient density) of PF. Pelleted high and low nutrient-density diets were blended to produce rations containing amino acid levels that matched the predicted PF requirements over 2-d intervals, and diets were switched every other day during PF. Treatments were replicated in 6 pens; each pen contained 15 males and 15 females. Weight gain, feed intake, and feed efficiency were calculated. All birds were commercially processed; yield and fillet dimensions were calculated. Differences among strain BW were noted on d 0, 18, 32, and at processing. Males weighed more than females on d 18 (excluding strain C), 32, and the day of processing. Weight gain was affected by strain (P < 0.05) but not by feeding regimen in the overall growth period (18-39 d). Feed efficiency was improved by PF in strains B and C during the overall growth period. Fillet yield was improved with PF for strain B, and there were no significant differences between PF and industry fillet yields for the other 2 strains. Phase feeding had no effect on fillet dimensions, and there was little effect of strain. These results suggest that different strains may vary in their response to PF, although performance was similar or better in PF birds compared with birds fed the industry diet, regardless of strain.

Big-bird programs: Effect of strain, sex, and debone time on meat quality of broilers.

The industry trend toward early deboning of chickens has led to the need to explore the effect on meat quality, including the effects of strain and sex. An experiment was conducted using broilers of 4 different high-yielding commercial strains chosen because of their common use in big-bird production. Of each strain, 360 birds were commercially processed at 59, 61, and 63 d of age in 2 replicates per day. Breast fillets were harvested at 2, 4, and 6 h postmortem (PM). Muscle pH and instrumental color (L*, a*, and b*) were measured at the time of deboning and at 24 h PM. Fillets were cooked to 76°C and cook loss was calculated, followed by Meullenet-Owens razor shear (MORS) analysis. Muscle pH significantly decreased over time as aging before deboning increased. Furthermore, L* values significantly increased as aging time increased, with the fillets deboned at 6 h PM having the highest L* value, followed by 4 h, and then 2 h PM. After 24 h, the fillets deboned at 6 h still had the highest L* compared with those deboned at 2 or 4 h PM. Fillets from strain B had the highest L* values. Fillets deboned at 2 h PM had significantly higher cook losses and MORS energy (indicating tougher fillets) than fillets deboned at 4 or 6 h PM, but there was no difference in cook loss due to strain at any deboning time. Fillets deboned at 4 h PM also had higher MORS energy than fillets deboned at 6 h PM, and differences in MORS energy among the strains were observed at 4 h PM. There was no difference in instrumental color values or cook loss due to sex. However, fillets of males had significantly greater MORS energy (tougher fillets) when deboned at 2, 4, and 6 h PM than those of females. Results of this study suggest that deboning time, sex, and strain can affect meat quality in big-bird market programs.

Small bird programs: effect of phase-feeding, strain, sex, and debone time on meat quality of broilers.

Phase-feeding (PF) has been effective in maintaining broiler growth while reducing production cost, but the effect on different broiler strains grown in a small-bird production scenario has not been assessed. The objective of this study was to evaluate 3 commercial broiler strains typically used in a small-bird production scenario to assess the effect of various debone times and PF on yield and meat quality. Birds (n = 1,080) were fed either diets with average industry nutrient levels or diets with phased levels of amino acids. In total, 540 birds were commercially processed at 40 and 42 d of age. Breast fillets were harvested at 2, 4, and 6 h postmortem (PM). Muscle pH was measured at the time of debone and fillet dimensions, instrumental color (L*, a*, and b*), and pH were measured at 24 h PM. Fillets were cooked to 76°C and cook loss was calculated, followed by Meullenet-Owens Razor shear (MORS) analysis. Phase-feeding, strain, and sex had little effect on fillet yield, but deboning at 2 h PM resulted in a higher fillet yield compared with that of later debone times. Strain, sex, and debone hour had significant effects on fillet dimensions, with strain A producing longer and wider fillets than strains B and C. Males had larger fillets than females (longer and wider), whereas deboning early resulted in significantly thicker fillets compared with those of later deboning. There were no differences in fillet dimensions due to PF, however, uniformity was improved. The PF treatment did not affect pH, color, cook loss, or MORS energy. Deboning at 2 h PM resulted in higher MORS energy, indicating decreased tenderness in 2 of the strains, whereas in one strain, tenderness was not affect by debone time. Results of this study suggest PF does not adversely affect yield or meat quality of broilers in small-bird programs but strain, sex, and debone time can affect quality. Results also suggest that strain can effect tenderness of breast fillets when deboned prerigor.

Influence of growth rate on the occurrence of white striping in broiler breast fillets.

White striping refers to the occurrence of different degrees of white striations on broiler breast fillets and thighs of larger broilers, yet little is known about its causes. Thus, the objective of the study was to estimate the occurrence of normal (NORM), moderate (MOD), and severe (SEV) degrees of white striping with respect to the growth rate of broilers and to compare their proximate composition without the confounding effect of diet. Straight-run 1-d-old chicks (n = 280) were randomly assigned to either a low- (LED) or high-energy (HED) diet (5 replicates of 28 birds/dietary treatment). Birds were processed at 54 d of age, and live weight, deboned fillet weight, and occurrence of white striping were recorded. As expected, birds fed the HED had lower (P < 0.05) feed conversion ratios than birds fed LED (2.08 vs. 2.28). Also, HED-fed birds had heavier P < 0.05) live and fillet weights when compared with the LED-fed birds. A greater (P < 0.05) percentage of breast fillets from LED-fed birds were scored NORM, whereas HED-fed birds produced a greater (P < 0.05) percentage of SEV fillets. Fillet weight and yield (percent of live weight) increased (P < 0.05) as the degree of white striping increased from NORM to SEV. Additionally, NORM fillets had greater (P < 0.05) lipid and lower (P < 0.05) protein content when compared with SEV fillets. Also, NORM fillets had greater (P < 0.05) percentages of SFA than SEV fillets; however, proportions of all monounsaturated fatty acids, as well as linoleic and linolenic acids, were greater (P < 0.05) in SEV than NORM fillets. These results suggest that an increased growth rate results in increased occurrence of higher degrees of white striping in broiler breast fillets, and the various degrees of white striping are associated with differences in chemical composition of breast fillets.

Effect of helium and oxygen on airflow in a narrowed airway.

A mixture of 80% helium and 20% oxygen has physical properties that increase airflow and decrease resistance in the airway when used as a portion of inspired gas. This study was designed to demonstrate and quantify the effects of a helium-oxygen mixture in a normal airway and when airway resistance is increased. Thirty healthy volunteers were studied breathing room air and the helium-oxygen mixture through a normal airway and an airway that included a resistor. Pulmonary function tests, directed by a registered respiratory therapist, were performed on all subjects using a computerized spirometer. The functional vital capacity, one-second forced expiratory volume, half-second forced expiratory volume, and peak inspiratory flow rate were analyzed. There was a statistically significant increase in 1-second forced expiratory volume using a helium-oxygen mixture in a normal airway. All pulmonary function test scores statistically improved when volunteers inspired helium and oxygen through the restricted airway, demonstrating that helium and oxygen can increase airflow in the presence of an increased airway resistance. This substantiates a role for helium and oxygen in treating conditions associated with decreased airway size and increased airway resistance.

Attention processes in children with shunted hydrocephalus versus attention deficit-hyperactivity disorder.

Children with congenital hydrocephalus, children with attention deficit-hyperactivity disorder, and normal controls were evaluated with measures of focused attention (Visual Orienting and Detection Task), sustained attention (continuous performance test), and attention shifting (Wisconsin Card Sorting Test). Components from these tasks have been linked to attention systems mediated by anterior or posterior brain networks. Children with congenital hydrocephalus showed an inability to focus and shift attention, which specifically implicated impairment of the disengage and move components of the posterior brain attention system. Children with attention deficit-hyperactivity disorder displayed the expected performance patterns on measures of focused attention once their difficulties with sustained attention were taken into account. However, they showed problems with shifting and sustaining attention, which are commonly associated with the anterior brain attention system.

Prospective evaluation of the brain in asymptomatic children with neurofibromatosis type 1: relationship of macrocephaly to T1 relaxation changes and structural brain abnormalities.

BACKGROUND AND PURPOSE: Mutation of the neurofibromatosis type 1 (NF-1) gene may be associated with abnormal growth control in the brain. Because macrocephaly could be a sign of abnormal brain development and because 30% to 50% of children with NF-1 display macrocephaly in the absence of hydrocephalus, we sought to determine the relationship between macrocephaly and other brain abnormalities in young subjects with NF-1. These subjects were free of brain tumor, epilepsy, or other obvious neurologic problems. METHODS: We prospectively screened 18 neurologically asymptomatic subjects with NF-1, ages 6 to 16 years, using clinical measures, psychometric testing, conventional MR imaging, and quantitative MR imaging to measure T1. RESULTS: Cranial circumference was 2 or more SDs above the age norm in seven (39%) of 18 subjects, a frequency of macrocephaly 17-fold higher than normal. Conventional MR imaging showed abnormalities in all 18 children, although there were more extensive abnormalities in subjects with macrocephaly. Macrocephaly in NF-1 was associated with enlargement of multiple brain structures, and brain T1 in macrocephalic subjects was reduced with respect to controls in the genu, frontal white matter, caudate, putamen, thalamus, and cortex. In normocephalic subjects, T1 was reduced only in the genu and splenium. Volumetric analysis showed that macrocephaly was associated specifically with enlargement of white matter volume. CONCLUSION: Neurologically asymptomatic children with NF-1 showed macrocephaly, cognitive deficit, enlarged brain structures, and abnormally low brain T1. Macrocephaly in children with NF-1 may be associated with characteristic alterations in brain development, marked by more widespread and significant changes in T1, greater enlargement of midline structures, and greater volume of white matter.

Role of exercise in prevention of involutional bone loss.

Physical inactivity has been cited as a possible cause of osteoporosis. Because involutional bone loss in the female can begin as early as age 40, the purpose of this investigation was to compare the skeletal status of two groups of premenopausal middle-aged (30-49 yr) women of diverse physical activity levels. Bone mineralization was determined by x-ray densitometry (middle phalanx of fifth finger and os calcis) and photon absorptiometry (distal and midshaft radius) in 42 marathon runners and 38 sedentary females. Mean values for bone mineral content (BMC) and bone density were greater in the marathon runners at the midshaft radius (P less than 0.05) and at the middle phalanx of the fifth digit (P less than 0.001). Mean density of the os calcis was higher in the physically inactive women (P less than 0.001). Following normalization of the data for differences in age and body size, regression analysis suggests that the runners maintain their bone mass longer at the distal radius, a site frequently fractured in women after midlife.

Possession and carrying of firearms among suburban youth.

Despite a growing body of anecdotal evidence suggesting the spread of firearms to suburban juvenile populations, most studies of firearm activity by juveniles focus either on urban youth or on nationally representative samples that blur urban and nonurban distinctions. This study represents the first systematic empirical investigation specifically of a suburban population of juveniles. The authors examine both ownership and carrying behaviors, distinguish types of handguns involved, and assess the influence of drug activity, violent criminality, and the perception of one's social environment as dangerous upon the possession and carrying of firearms. Among the variables linked at the bivariate level to possession and carrying of guns were sex, involvement in criminal activity, involvement in drug activity, and most indicators of a dangerous social environment. At the multivariate level, however, only sex was associated with possession of a revolver, and only sex, criminal activity (for boys only), and one indicator of dangerous environment (having been threatened with a gun, for girls only) were associated with possession of an automatic or semiautomatic handgun. Aside from sex, criminal and drug activities were associated with gun carrying. Despite its importance among urban samples, in this study the dangerous environment was not linked to firearm activity. Possible reasons for this difference are explored in the conclusion.

Assessing the relationship between child sexual abuse and marginal living conditions on HIV/AIDS-related risk behavior among women prisoners.

OBJECTIVE: There were two aims in this research. First, to examine the relationships between childhood sexual abuse and HIV drug and sexual risk taking behaviors among female prisoners, and second, to examine the relationship between a marginal adult living context and HIV drug and sexual risk taking behavior among female prisoners. METHOD: The data were collected through face-to-face interviews with a random sample of 500 women at admission to prison in 1994. Differences between women who were sexually abused while growing up (n = 130) were compared to women who reported no sexual abuse (n = 370) along various demographic, and HIV drug and sexual risk taking dimensions. RESULTS: A history of sexual abuse while growing up was associated with increased sexual risk taking behaviors in adulthood. A marginal adult living situation also emerged as an important factor increasing the risk for HIV infection. Examining the co-occurrence of both childhood sexual abuse and adult marginal living context revealed a strong relationship between these two factors and HIV risk taking activities. CONCLUSIONS: The findings indicate that childhood sexual abuse may be a predictor for HIV sexual risk taking behaviors among incarcerated women. The marginal and chaotic adult living style of these women was also associated the extent of their HIV drug and sexual risk taking behaviors. Our research suggests that the co-occurrence of sexual victimization and marginality is a stronger predictor of HIV risk than each variable alone.

Learning disability subtypes in children with neurofibromatosis.

A high incidence of learning disabilities (LD) has been reported in children with neurofibromatosis Type 1 (NF-1), and many children affected with this disease are thought to have a form of LD that is characterized by selective visuospatial and motor deficits. However, the evidence is subject to sampling biases and is limited by the clinical-inferential methods used to classify children into LD subtypes. In the present study, objective statistical methods were used to categorize LD in 105 children with NF-1 between the ages of 6 and 18 years. A cluster analysis of achievement test scores yielded 10 groups; 6 of which met our criterion for academic deficiency. An analysis of neuropsychological data for 72 children with academic deficiencies with complete neuropsychological data yielded three groups: a neuropsychologically normal group (n = 28), a group with general academic deficiencies (n = 34), and a group with visuospatial-construction deficiencies (n = 10). The low incidence of visuospatial-constructional deficits and the absence of cases involving pure linguistic deficits is notable.

A sex-specific analysis of correlates of homicide victimization in United States cities.

A considerable amount of research has been devoted to determining structural correlates of homicide across places in the United States. However, recent research has found that general correlates may not hold when homicide rates are disaggregated into analysis of specific groups. Adopting a public health approach, we explore the possibility that male and female rates of homicide victimization may show differential patterns of association with selected social-structural risk factors across a sample of U.S. central cities. The results show that both male and female homicide victimization is related to a general set of factors derived from the theoretical framework of social disorganization. At the same time, it is found that these factors are better predictors of male than female homicides. Suggestions are made for research to discern additional factors, perhaps distinct from those of men, related to the rather considerable variation in the prevalence of female homicide across communities in the United States.

Resistance to extinction following habituation to behaviourally disruptive novel stimuli.

Three experiments tested the prediction, derived from generalized frustration theory (Amsel, 1972), that habituation to behaviourally disruptive stimuli increases resistance to extinction in the runway. In each experiment, rats received initial consistent reinforcement (CRF) training and then either continued CRF (Groups C), partial reinforcement (PRF) training (Groups P), or CRF accompanied by presentations of a novel tactile, tone, or obstacle stimulus (Groups D) in Experiments 1-3, respectively. PRF increased resistance to extinction whether non-reinforcement disrupted behaviour (Experiment 1) or not (Experiments 2 and 3). The tactile and obstacle stimuli very substantially disrupted behaviour, and the tone produced a modest disruption of behaviour. All subjects habituated to the disruptive effects of these stimuli, but Group D was not more resistant to extinction than Group C in any experiment. The results suggest that non-reinforcement has unique stimulus properties, a consequence of which is that habituation to other sources of disruptive stimulation does not promote responding to non-reinforcement in extinction.

Risk factor analysis for breast cellulitis complicating breast conservation therapy.

Women who undergo breast conservation therapy for early-stage breast cancer can develop breast cellulitis, a complication for which risk factors are undefined. A matched case-control investigation was conducted to identify risk factors for the development of breast cellulitis among patients who have undergone breast conservation therapy. Patients comprised 17 patients with cases of breast cellulitis diagnosed after partial mastectomies that had been performed from 1992 through 1997 and 34 control patients who were matched to case-patients by date of breast lumpectomy and by primary surgeon. Statistical analyses indicated the following factors were associated with breast cellulitis: drainage of a hematoma (P=.010); postoperative ecchymosis (P=.021); lymphedema (odds ratio [OR], 10. 154; 95% confidence interval [CI], 1.348-208.860); resected breast tissue volume (OR, 1.456; 95% CI, 1.035-2.168); and previous number of breast seroma aspirations (OR, 3.445; 95% CI, 1.036-19.771). This is the first matched case-control study to identify risk factors for the development of breast cellulitis after breast conservation therapy.