Infection control and management of MRSA: assessing the knowledge of staff in an acute hospital setting.

Much of the recent work in tackling meticillin-resistant Staphylococcus aureus (MRSA) has focused on hygiene in hospitals, but it is unclear how much hospital staff know about the treatment and management of patients who are colonized or infected with MRSA. The aim of this study was to assess the knowledge and perceived practice of staff regarding MRSA and its management in an acute hospital setting. A further aim was to determine what staff felt was needed in terms of information or education on the risks, management and treatment of MRSA. A questionnaire survey was carried out through group administration during a study day and by face-to-face interviews. Subjects included in the questionnaire were infection and colonization, treatment, and the availability of local support and advice. There were 174 responses, divided equally between doctors and nurses. Knowledge on many aspects of MRSA and its management was deficient, although the majority of participants who felt that they required additional information about MRSA acknowledged this. The survey confirmed that assumptions should not be made about adequate knowledge and expertise of staff in relation to MRSA. Gaps in awareness of aspects of care and management were highlighted and information and educational needs identified.

Effects of long-term therapy with naltrexone on body weight in obesity.

The endogenous opiate system is thought to be associated with the regulation of food intake and body weight. Opiate antagonists decrease food intake in animals, but there are no controlled studies in obese man to evaluate body weight response to naltrexone. Sixty obese people were randomized into three groups and given 0, 50, or 100 mg of the opiate antagonist naltrexone for 8 weeks in an outpatient, double-blind study. Weight loss was not significant in either the 50 or 100 mg groups as compared with placebo. However, when broken down by sex, women had a significant (P less than 0.05) weight loss of 1.7 kg, while men did not lose weight. Side effects were modest, but six subjects had one or more abnormal liver function test results; in one subject these abnormalities appeared to be clinically significant. The effects of naltrexone on weight loss were less than expected in light of prior animal studies, but further studies with a wider dose range of naltrexone may be indicated.

Design, synthesis, and testing of potential antisickling agents. 4. Structure-activity relationships of benzyloxy and phenoxy acids.

In this paper we further establish the activity of two classes of small molecules, benzyloxy and phenoxy acids, as potent inhibitors of hemoglobin S (HbS) gelation. Structural modifications with a large number of each class confirm our earlier work that the highest activity is observed with compounds that contain dihalogenated aromatic rings with attached polar side chains. We have also found a halogenated aromatic malonic acid derivative to be quite active. Compounds reported in this paper are compared with other antigelling agents studied in our laboratory. Comments are made concerning the antigelling activity and binding sites of four derivatives and their effect on the allosteric mechanism of hemoglobin (Hb) function.

Low sex ratios of births in areas at risk from air pollution from incinerators, as shown by geographical analysis and 3-dimensional mapping.

Previous research in environmental and occupational health has suggested that fluctuations in the sex ratios of births might provide a useful early warning to the possible health effects of toxins or other stresses in the environment. To examine further this hypothesis, we investigated the sex ratios of births in an area in central Scotland which contained two incineration plants. Analyses of the sex ratios, at various levels of geographical detail and using 3-dimensional mapping techniques, in the residential areas at risk from airborne pollution from these incinerators showed locations with statistically significant excesses of female births.

PIP: Researchers calculated sex ratios of births for the 3 control areas and 4 comparison areas of Falkirk District in central Scotland based on 1975-1983 birth records to determine if abnormal sex ratios of births occurred in areas at risk from airborne pollution from 2 incinerators in the Larbert area. These incinerators had stopped operating before the study began in the early 1990s. A significant excess of female births occurred in 1 of the most at risk areas in both 1975-1979 and 1980-1983 (p.05). Further another at risk area also had excess female births, but the excess was not significant. The other at risk area had an excess of male births, again not a significant excess. Yet there were no significant differences between the total at risk areas and the comparison areas. Computer mapping analysis revealed a definite northeast-southwest axial pattern of excess female births. A possible explanation for the lack of complete uniformity in excess female births may be that the incinerators' plumes contained several pollutants and different toxins change the sex ratios in different ways. Besides wind direction, particulate size, and weather conditions influenced fall out of particulates differently. Other researchers have shown that some pollutants affect metabolism of rapidly dividing cells of gonadal and fetal tissues. For example, a study of workers' exposure to the nematocide DBCP suggested damage to the spermatozoa bearing the Y chromosome. This study's researchers have found similar associations between airborne pollution and abnormal sex ratios. If indeed airborne pollution exposure influences sex ratios, the presence of abnormal sex ratios can be used as a screening procedure to forewarn medical and environmental health authorities of health hazards.

UK study of intrapartum care for low risk primigravidas: a survey of interventions.

STUDY OBJECTIVE: To determine the extent of intrapartum intervention received by primigravidas. DESIGN: Cross sectional survey of NHS hospitals in the UK. SETTING: One hundred and one randomly selected hospital maternity units. PARTICIPANTS: Forty consecutive primigravid women, judged to be at low risk at the start of labour, in each hospital. MAIN OUTCOME MEASURES: Seven groups of interventions or monitoring procedures were identified from the first, second, and third stages of labour: fetal monitoring, vaginal examinations, artificial rupture of membranes, augmentation of labour, pain relief, type of delivery, and episiotomy. Data were collected during 1993. MAIN RESULTS: Ninety eight hospitals took part in the study and data were collected on 3160 low risk primigravidas. Seventy four per cent of these women had continuous cardiotocography. The proportion of women having restrictive or invasive fetal monitoring showed appreciable geographical variation for both the first and second stages of labour. Using the criterion of a vaginal examination every four hours and allowing for the length of each woman's labour, 72% had more vaginal examinations than expected; there was a significant geographical variation in the number of women receiving more than five examinations. Fifty three per cent had artificial rupture of membranes; the procedure was performed over a wide range of cervical dilatations (0 cm-10 cm). Thirty eight per cent of labours were augmented, most commonly by intravenous syntocinon; the procedure showed significant geographical variation. Twenty eight per cent had a spinal block or epidural analgesia for the relief of pain; this intervention varied by geographical region only for the second stage of labour. Over one quarter of the women required instrumental delivery. Forty six per cent had an episiotomy; the frequency of this intervention varied substantially by region. There were no infant deaths. Twelve babies were recorded at birth as having a congenital anomaly. CONCLUSIONS: The rates of several interventions seem high for this low risk group and there was substantial geographical variation in the use of six interventions. Clinical trials are needed to evaluate the optimum criteria for using these interventions from which guidelines should be drawn up by local groups and the Royal College.

Feasibility of an outpatient and home parenteral antibiotic therapy (OHPAT) programme in Tayside, Scotland.

Outpatient and home parenteral antibiotic therapy (OHPAT) is under-utilized in the U.K. We performed a feasibility study over a 5-month period in a regional U.K. infection unit. After exclusions, 183 antibiotic treated patients were evaluated. Ninety-five received intravenous (i.v.) therapy, of whom 32 received at least 4 days. Prolonged i.v. therapy was most frequent in soft tissue infections. In these patients, length of stay and duration of i.v. treatment were correlated (r = 0.74, 0.51-0.87). Eighty-three (86%) of patients who received IV therapy judged OHPAT to be an acceptable alternative to hospitalization. Those who did not were older (mean age 64 vs. 46 years, P<0.001) and were less likely to have a carer willing to administer the antibiotic at home (8/28 vs. 117/151, P<0.001). Twenty-five of 32 (79%) patients treated with prolonged parenteral therapy and 27/95 (28%) treated with any length of parenteral therapy met criteria for OHPAT. Thirteen of these were safely and successfully managed as outpatients by ward staff, OHPAT is an acceptable alternative to inpatient therapy in Tayside and may reduce the duration of hospitalization or prevent admission in certain patients.

Iodine deficiency associated with parenteral nutrition in extreme preterm infants.

Infants are in negative iodine balance on current standard regimens of total parenteral nutrition, with a mean iodine intake of 3 micro g/kg/day (150 ml/kg/day). The recommended enteral intake of iodine for preterm infants is 30 micro g/kg/day. Gastrointestinal absorption of iodine is high, suggesting that parenteral intakes should approach enteral recommendations.

Coupling fields and underlying space curvature: an augmented Lagrangian approach.

We demonstrate a systematic implementation of coupling between a scalar field and the geometry of the space which carries the field. This naturally gives rise to a feedback mechanism between the field and the geometry. We develop a systematic model for the feedback in a general form, inspired by a specific implementation in the context of molecular dynamics (the so-called Rahman-Parrinello molecular dynamics, or RP-MD). We use a generalized Lagrangian that allows for the coupling of the space's metric tensor to the scalar field, and add terms motivated by RP-MD. We present two implementations of the scheme: one in which the metric is only time-dependent (which gives rise to an ordinary differential equation for its temporal evolution), and the other with spatiotemporal dependence (wherein the metric's evolution is governed by a partial differential equation). Numerical results are reported for the (1+1)-dimensional model with a nonlinearity of the sine-Gordon type.

Toxicity from ragwort and fat cow syndrome, or from industrial chemicals: the value of epidemiological analysis for interpreting clinico-pathological findings.

When livestock in close proximity to industries develop signs of ill-defined disease, toxic effects from industrial pollution should be considered in the differential diagnosis. In establishing the final diagnosis, epidemiological methods should be applied to supplement the clinical and pathological techniques. This viewpoint is illustrated by two case-histories describing episodes of cattle disease in central Scotland. A long-established and successful dairy herd in central Scotland sustained severe morbidity and mortality amongst animals which had grazed on a field beside a recently established dump which contained wastes from a chemical waste incinerator. An official investigation concluded that the episode of disease was the result of ragwort poisoning; this diagnosis was reached on clinical and pathological grounds only. A similarly unexpected and severe epidemic occurred a few years later in another dairy herd, about 1 km further away from that incinerator (which was also within 100 m of a municipal incinerator). The official investigation, which again focused on clinical and pathological criteria, led to the diagnosis of fat cow syndrome. In the first episode, contaminated water drained from the chemical waste dump on to the cows' field; in the second episode, the relevant field was affected by airborne pollution from the two waste incinerators mentioned earlier. In both episodes, the epidemiological features, which were not examined systematically by the original investigators, were consistent with the hypothesis that these episodes resulted from exposures to toxic contaminants.

Deposition and distribution of carcass fat for steers differing in frame size and muscle thickness.

Yearling feeder steers (n = 324) representing nine frame size (Large, Medium, Small) x muscle thickness (No. 1, No. 2, No. 3) subclasses were serially slaughtered at 28-d intervals during a 140-d finishing period. Weights for total dissectible (TDF) and subcutaneous fat (SQ) from each of nine wholesale cuts were recorded. Resulting data were analyzed using allometry (Y = aXb and Y = aXb10cx) to characterize deposition patterns for fat and to determine effects of feeder cattle frame size (F) and muscle thickness (M) on relative fat deposition and distribution. Patterns of TDF and SQ deposition were similar among cuts. As the steers became fatter, relative proportions of TDF and SQ in the abdominal and dorsal regions of the carcass increased and relative proportions of fat in the distal regions decreased. There was a tendency for the growth impetus of TDF and SQ to shift from the ventral portions of the carcass toward the dorsal region of the carcass as fattening progressed. Despite significant among-class differences in allometric coefficients, relative proportions of TDF and SQ in the nine wholesale cuts were remarkably similar for all nine F x M subclasses when compared at a constant percentage of total carcass fat. At endpoints of either a constant fat thickness measurement or a constant USDA marbling score, subclass differences in fat distribution were negligible.

Effects of feeder cattle frame size, muscle thickness, and age class on days fed, weight, and carcass composition.

Feeder steers (n = 189) representing nine frame size x muscle thickness subclasses were started on a high-concentrate diet as calves, yearlings, or long yearlings and slaughtered at a constant s.c. fat thickness (13.5 mm) to determine the effects of feeder cattle frame size (large, medium, small), muscle thickness (No. 1, No. 2, No. 3), and age class on carcass traits and composition. After slaughter, one side of each carcass was physically separated into muscle, fat, and bone. Subcutaneous, intermuscular, and internal fat depot percentages were calculated as proportions of total fat weight. Effects of age class, frame size, and muscle thickness were significant for time-on-feed, slaughter weight, and carcass weight. Among age classes, long yearling steers required the fewest (P < .05) days on feed and heaviest (P < .05) live weights to reach the fat thickness end point. Increased frame size and decreased muscle thickness were associated with greater time-on-feed and heavier weights at slaughter. However, the effects of muscle thickness on slaughter traits were not consistent among frame and age subclasses; effects were greatest among large-framed steers and smallest among long yearling steers. Compositional differences (P < .05) were noted among age and muscle subclasses. Long yearling steers had the lowest (P < .05) percentage of bone among all age classes and a higher (P < .05) percentage of fat than steers fed as calves. No. 2 steers had the highest (P < .05) percentage of bone and the lowest (P < .05) muscle:bone ratio among muscle thickness groups; no (P > .05) compositional differences were observed between No. 1 and No. 3 steers. Differences in muscle:bone ratio, though statistically significant, were relatively small in magnitude and were not directionally consistent with differences in muscle thickness. Differences in fat partitioning were noted among frame and muscle subclasses. Large-framed steers had the lowest (P < .05) percentage of s.c. fat and the highest (P < .05) percentage of internal fat among frame sizes. No. 3 steers deposited the lowest (P < .05) percentage of intermuscular fat and the highest (P < .05) percentage of internal fat.

Influence of diet on growth rate and carcass composition of steers differing in frame size and muscle thickness.

One hundred seventy-three steer calves, selected at weaning to represent USDA classifications for frame size (Large, L; Medium, M; Small, S) and muscle thickness (No. 1, No. 2, No. 3), were assigned to three finishing diets (grain, 3.03 Mcal ME/kg DM; silage, 2.46 Mcal ME/kg DM; forage, 2.06 Mcal ME/kg DM), forming a 3 x 3 x 3 factorial with unequal subclass numbers. The steers were slaughtered at constant weights corresponding to their respective frame size classifications (L = 590 kg, M = 499 kg; S = 408 kg). Individual live weights were recorded every 28 d during finishing and, following slaughter, one side of each carcass was dissected into muscle, bone and fat. Diet interacted with frame size to affect growth rate. Frame-related differences in growth rate were very pronounced among grain-fed steers (L greater than M greater than S) but became smaller in magnitude as feeding intensity was reduced. Diet also had a significant effect on percentage separable carcass fat, despite the fact that the steers were slaughtered at a similar percentage (approximately 60%) of their estimated potential mature weights. Carcasses produced by grain-finished steers were fattest, and those produced by forage-finished cattle were leanest. The comparative fatness of steers finished on silage was dependent on frame size. Within the L class, carcasses produced by silage-finished steers were comparatively lean and were similar in fatness to carcasses produced by forage-finished cattle. Conversely, S steers finished on silage produced carcasses that were comparable in fatness to carcasses from grain-finished cattle. Frame-related differences in percentage carcass fat were significant only within the silage treatment group (S greater than L). Differences in carcass muscle-to-bone ratio were directionally consistent with visually discernible differences in feeder cattle muscling (No. 1 greater than No. 2 greater than No. 3). The effects of muscle thickness on muscle-to-bone ratio were most pronounced within the L class.(ABSTRACT TRUNCATED AT 400 WORDS)

Relationship of visual assessments of feeder lamb muscularity to differences in carcass yield traits.

We examined the relationship between visual differences in muscle thickness among feeder lambs and subsequent differences in carcass composition. Medium-framed, crossbred feeder lambs (n = 120) were selected at two commercial feedlots to exhibit distinct phenotypic differences in muscularity. The lambs were assigned scores (ranging from 1 to 9; 1 = extremely thin, 5 = average, 9 = extremely thick) for muscle thickness and were sampled serially on d 0, 14, 28, and 42 of the trial. After recording yield grades, one side of each carcass was deboned, and the soft tissues from the entire side were ground, sampled, and analyzed for lipid and moisture content. The opposite side was fabricated into boneless, closely trimmed (.25 cm maximum fat depth) subprimal cuts. When lambs of the same frame size were compared at the same live weight, greater muscle thickness was associated with greater (P < .05) fat-free muscle mass. Correspondingly, thickly muscled lambs produced carcasses of a given weight that had a higher (P < .05) composite yield of lean meat and a lower (P < .05) proportion of trimmable fat compared with carcasses of thinly muscled lambs. When comparisons were made at the same percentage of extractable fat in the carcass, greater muscle thickness was associated with heavier (P < .05) live and carcass weights, increased (P < .05) fat-free muscle mass, and increased (P < .05) weights of trimmed, boneless subprimal cuts. Results suggest that visual assessments of muscle thickness in feeder lambs, as applied in this study, are indicative of commercially important differences in carcass yields of lean meat.

Development of a multivariate yield grade equation to predict compositional traits in mature cow carcasses.

Data from 68 cow carcasses were used to develop a new yield grading system. First principal component (FPC) values for compositional attributes (LNFT = separable lean weight/[lean+fat weight] x 100, LNBN = separable lean weight/[lean+bone+connective tissue weights] x 100, and BTPR = [defatted lean from the round, loin, rib, and chuck]/side weight x 100) were determined. The first component explained 83.5% of the standardized variance and load values were .63, -.52, and .58, respectively. The resulting FPC values ranged from -1.93 to 1.89. The linear regression of LNFT, LNBN, and BTPR (dependent variables) on FPC (independent variable) explained a significant amount of variation (P less than .001) in each case and resulted in R2-values of .98, .67, and .85, respectively. A best-fit yield grade equation, developed to predict FPC, included adjusted fat thickness (ADF), percentage of kidney, pelvic, and heart fat (KPH), and overall muscling grade (OM). The equation, FPC = 2.04 - (.67 x ADF) - (.21 x KPH) - (.0016 x OM), explained a significant amount (P less than .001) of variation in FPC with R2 = .94 and residual standard deviation = .25. Simple correlations for ADF, KPH, and OM with FPC were -.87, -.71, and -.80, respectively. Cow carcasses were assigned to one of three grades based on FPC values that corresponded with predetermined levels of LNFT, LNBN, and BTPR. These grades generally had smaller CV than existing grades. When used in conjunction with quality grades, proposed grades could be more useful to the cow meat industry.

Development of a quantitative quality grading system for mature cow carcasses.

Data from 400 cow carcasses were used to develop a new quality grading system. First principal component (FPC) values were determined for shear force (SHR) and palatability attributes of tenderness, connective tissue amount, flavor, and juiciness (JUC). Associated eigenvector load values for those traits were -.48, .54, .51, .46, and .05, respectively, and FPC values ranged from -3.20 to 2.18. Linear regression, using FPC as the independent variate, and SHR and palatability attributes (8-point scale, where 8 was highest) as dependent variates explained a significant amount of variation (P less than .001) in all traits, except JUC, and resulted in R2 values of .71, .89, .80, .66, and .01, respectively. A predictive quality-grade equation was developed using FPC as the dependent variate, and overall maturity (OM), lean color, marbling score (MS), lean firmness, lean texture, fat color (FC), and marbling fineness ([marbling texture + marbling distribution]/2; 8-point scale, where 8 was highest) as independent variates. The resulting best-fit prediction equation (FPC = -.052-[.0031 x OM] + [.0013 x MS] + [.31 x FC]) explained a significant amount (P less than .001) of variation in FPC with R2 = .53, Cp = 15.0, and residual standard deviation = .69. A short-cut equation was developed from this prediction equation. Simple correlations for OM, MS, and FC with FPC were -.56, .39, and .64, respectively. Cow carcasses were assigned to one of three quality grades based on FPC values that corresponded with predetermined acceptability levels for each palatability trait. Newly developed grades were quantitative and less variable than existing grades. Future grades for cow carcasses should include fat color to predict palatability.

An evaluation of the USDA standards for feeder cattle frame size and muscle thickness.

This study was conducted to determine the live weights at which large-, medium-, and small-framed feeder steers and heifers attain a degree of finish associated with a carcass quality grade of low Choice and to examine the relationship of feeder cattle muscle thickness to carcass yield grade traits. Feeder steers (n = 401) and heifers (n = 463) representing three age classes (calf, yearling, long yearling) were selected randomly at a commercial feedlot to exhibit wide ranges in frame size and muscularity. Individual weights were recorded and a panel of five experienced evaluators scored each animal for frame size, muscle thickness, and flesh condition. The cattle were finished on a high-concentrate finishing diet and harvested at an estimated carcass fat thickness of 10 mm. Final weights and USDA carcass grade data were collected for all cattle. Frame size scores effectively predicted finished weight at a marbling end point of Small(00) for both heifers (r2 = 0.89, SE = 16 kg) and steers (r2 = 0.94, SE = 13 kg). For heifers, the Small/Medium and Medium/ Large frame score intersects corresponded to live weights of 460 kg and 520 kg, respectively. For steers, the Small/Medium and Medium/Large frame score lines corresponded to live weights of 504 kg and 577 kg, respectively. These weights were greater than weights specified in the 1979 USDA grade standards. Evaluations of feeder cattle muscling, based on 1979 USDA Standards, were associated (P < 0.05) with differences in longissimus muscle area but were not related (P = 0.08) to differences in numerical carcass yield grades. An alternative muscle thickness classification scheme, involving the use of four thickness classes, was effective for stratifying feeder cattle according to eventual differences (P = 0.004) in carcass yield grade. Our findings suggest that USDA feeder cattle grade standards developed in 1979 are no longer adequate for describing today's population of feeder cattle.

Relationship of feeder lamb frame size to feedlot gain and carcass yield and quality grades.

Small-(S), medium-(M), and large-(L) framed feeder lambs (n = 243 S, 247 M, and 245 L) were finished on five diets differing in amount of concentrate (C) and crude protein (CP): 1) 30% C, 12.5% CP; 2) 55% C, 12.5% CP; 3) 55% C, 14.5% CP; 4) 80% C, 12.5% CP; and 5) 80% C, 14.5% CP. Lambs were sampled over a wide weight range to establish relationships of frame size to daily gain and live weight at specific carcass grade end points. Increased frame size (F) was associated with more rapid gains during finishing, although differences in daily gain among L, M, and S lambs were not expressed consistently across all dietary treatments (D), as reflected by a significant F x D interaction for ADG. The rate at which external fat thickness increased as the lambs became heavier was not affected by frame size, sex, or diet. However, increased frame size was associated with lower (P < .05) values for fat thickness (FT), body wall thickness (BWT), yield grade (YG), and quality grade (QG) when comparisons were made at a constant slaughter weight. Similarly, later-maturing wether lambs were leaner and had lower YG and QG than ewes of the same weight. Dietary treatment had no effect on FT, BWT, and YG when treatment groups were compared at a constant live weight. Subclass regressions of YG on live weight were used to project the weights at which lambs of various frame sizes would be expected to produce YG-2 carcasses. Projected final weights for wethers were less than 50 kg for S, 50 to 55 kg for M, and greater than 55 kg for L. Projected final weights for ewe lambs were approximately 2.5 kg lower. Dietary treatment did not affect relationships among frame size, live weight, and YG. A grading/classification system for feeder lambs based on frame size could be developed to predict carcass grade end point.

Influence of gender, breed and age on maturity characteristics of sheep.

Fifty-one ewes, 50 wethers and 51 rams of Finn x whiteface or Suffolk x whiteface breeding were slaughtered at an average age of 271, 361, 459, 557 or 652 d to study changes in maturity characteristics with changes in age. When metacarpal epiphyseal cartilage (growth plates) ossifies with age, break joints on the distal end of the metacarpals fuse and the end of the bone then appears as a spool joint rather than as a break joint. This fusion occurs earlier chronologically in ewes than in rams or wethers. Most Finn x whiteface-cross ewes, which normally reach reproductive maturity earlier than Suffolk x whiteface-cross ewes, exhibited ossified metacarpal growth plates by 459 d of age; break joints of Suffolk x whiteface crosses were not fused until 557 d of age. Both breed groups of rams exhibited fused joints by 557 d of age, but only 3 of 10 wethers exhibited spool joints at 652 d of age. Microscopic examination showed that even in these three wethers the epiphyseal growth plate could still be detected. Yearling 2-yr-old classifications of sheep from teeth were not gender-dependent within the discrete age classes of this study. About half the sheep in each gender group were classified as yearlings at 459 d of age and about half in each group were classified as 2-yr-olds by 652 d of age. Stepwise multiple regression equations to estimate age of sheep in days were developed. Overall maturity, lean color and texture and rib bone maturity were the best carcass measures of maturity. Maturity scores for characteristics of the break joint did not enter any of the equations studied. When eye lens weight was included in equations with the best measures of carcass maturity, accuracy of estimates for age of sheep was improved.

Influence of age and testosterone levels on masculine development in rams.

Fifty wethers and 51 spring-born rams were divided into five groups and slaughtered at different seasons of the year at average ages of 271, 361, 459, 557 or 652 d to determine the age and season at which differences in secondary sex characteristics could be detected. Serum testosterone concentrations and testes weights were low in January when the rams were 271 d of age and again in April at 361 d of age. By July, at 459 d of age, testosterone concentrations and testes weights had peaked and then decreased the following November at 557 d and February at 652 d. In contrast with plasma testosterone concentrations and testes weights, buckiness scores, splenius to semimembranosus or semitendinosus muscle ratios, splenius muscle weights and neck and shoulder percentages were not seasonal. All of these measures increased significantly up to July and continued to increase slowly, but not significantly, thereafter. Muscle color and texture scores and rib eye color scores tended to increase in a linear manner for both rams and wethers as age increased. Subcutaneous fat from rams was yellower and softer than that from wethers over all age groups. Ram fat firmness did not change (P greater than .05) with age, and the only significant change in ram fat color was between the groups at 271 and 361 d of age. Overall, season of year coupled with higher levels of serum testosterone was related to initial development of secondary sex characteristics in ram lambs.

Beef carcass composition of slaughter cattle differing in frame size, muscle score, and external fatness.

Commercial slaughter steers (n = 329) and heifers (n = 335) were selected to vary in slaughter frame size and muscle thickness score, as well as carcass adjusted 12th-rib fat thickness. After collection of USDA carcass grade data, one side of each carcass was fabricated into boneless primals, subprimals, and minor tissue components. Cuts were trimmed to 2.54, 1.27, and .64 cm of external fat, except for the knuckle, tri-tip, and tenderloin, which were trimmed of all fat. Forced four-variable regression equations were used to predict the percentage (chilled carcass weight basis) yield of boneless subprimals at the three fat trim levels as influenced by sex class, frame size, muscle score, and adjusted 12th-rib fat thickness. Independent variables that had the most influence on percentage yield of primals and boneless subprimals were adjusted 12th-rib fat thickness and sex class. Within the same phenotypic group, percentage of trimmable fat increased by 2.32% as 12th-rib fat thickness increased by .75 cm. Estimated percentage yield of the major subprimals from the loin and round tended to be higher or relatively equal for heifer carcasses at all trim levels compared with those subprimals from steer carcasses. Holding frame size, sex class, and fat thickness constant, there was a higher percentage yield of chuck roll, rib eye roll, and strip loin for carcasses from thick-muscled cattle than for those from average- and thin-muscled cattle. Frame size had little effect on percentage yield of boneless subprimals.