Beef longissimus slice shear force measurement among steak locations and institutions

The objectives of this study were 1) to determine which longissimus thoracis et lumborum steaks were appropriate for slice shear force measurement and 2) to determine the among and within institution variation in LM slice shear force values of 6 institutions after they received expert training on the procedure and a standard kit of equipment. In experiment 1, longissimus thoracis et lumborum muscles were obtained from the left sides of 50 US Select carcasses. Thirteen longissimus thoracis and 12 longissimus lumborum steaks were cut 2.54 cm thick from each muscle. Slice shear force was measured on each steak. Mean slice shear force among steak locations (1 to 25) ranged from 19.7 to 27.3 kg. Repeatability of slice shear force (based on variance) among steak locations ranged from 0.71 to 0.96. In experiment 2, the longissimus thoracis et lumborum were obtained from the left sides of 154 US Select beef carcasses. Eight 2.54-cm-thick steaks were obtained from the caudal end of each frozen longissimus thoracis, and six 2.54-cm-thick steaks were obtained from the cranial end of each frozen longissimus lumborum. Seven pairs of consecutive steaks were assigned for measurement of slice shear force. Seven institutions were assigned to steak pairs within each carcass using a randomized complete block design, such that each institution was assigned to each steak pair 22 times. Repeatability estimates for slice shear force for the 7 institutions were 0.89, 0.83, 0.91, 0.90, 0.89, 0.76, and 0.89, respectively, for institutions 1 to 7. Mean slice shear force values were least (P <0.05) for institutions 3 (22.7 kg) and 7 (22.3 kg) and were greatest (P <0.05) for institutions 5 (27.3 kg) and 6 (27.6 kg). Institutions with greater mean slice shear force (institutions 5 and 6) used cooking methods that required more (P <0.05) time (32.0 and 36.9 min vs. 5.5 to 11.8 min) to reach the end point temperature (71 degrees C) and resulted in greater (P <0.05) cooking loss (both 26.6% vs. 14.4 to 24.1%). Differences among institutions in the repeatability of slice shear force were partially attributable to differences among institutions in the consistency of steak thawing and cooking procedures. These results emphasize the importance of sample location within the muscle and cooking method in the measurement of tenderness and indicate that with proper training and application of the protocol, slice shear force is a highly repeatable (R approximately 0.90) measure of beef LM tenderness.     

Across-breed adjustment factors for expected progeny differences for carcass traits

Adjustment factors to allow comparison of EPD from several breed associations for birth, weaning, and yearling weights have been available for more than 10 yr. This paper describes steps to calculate adjustment factors for EPD for 4 carcass traits: marbling score, fat thickness, ribeye area, and retail product percentage. The required information is the same as for the weight traits: 1) breed of sire solutions based on measurements on progeny at the US Meat Animal Research Center (USMARC) that have sires with breed association EPD, 2) mean EPD of sires weighted by number of progeny at USMARC (USMARC progeny not included in breed association EPD), and 3) mean EPD of nonparents from breed associations (defined as animals born 2 yr prior to calculation of EPD). Records at USM-ARC are adjusted to 100% heterozygosity because the purpose of the adjustment factors is to allow prediction of performance of progeny of sires mated to other breeds of dam. A critical step is to adjust breed of sire solutions, which are based on an earlier sample of sires, to the equivalent of a sample from a more recent nonparent group using the difference between mean EPD from information sources 2) and 3). The difference is multiplied by the coefficient of regression of USMARC progeny on EPD of their sires. With weight traits, these coefficients are not greatly different from unity. With the carcass traits, 2 sets of coefficients can be used depending on whether the EPD are based on carcass or ultrasound measurements. The regression coefficients also reflect differences in conditions for USMARC progeny (all steers) and factors associated with breed association EPD. Only for marbling score and ribeye area were any estimates of the regression coefficients near unity. For other traits, the coefficients ranged from 1.65 to 2.82. The solutions for breed of sire, differences in mean EPD, and regression coefficients are then used to calculate adjustment factors for EPD of 11 breeds including the arbitrary base breed, Angus.     

Evaluation in beef cattle of six deoxyribonucleic acid markers developed for dairy traits reveals an osteopontin polymorphism associated with postweaning growth

The objectives of this study were to 1) estimate the allelic frequencies in US beef cattle of 6 DNA markers reported to be associated with variation in dairy production traits; and 2) evaluate the association of these markers with beef production traits. Several genetic markers have been associated with milk yield or composition, including polymorphisms in secreted phosphoprotein 1 (SPP1; also called osteopontin), growth hormone receptor (GHR), casein S1 (CSN1S1), diacylglycerol O-acyltransferase 1 (DGAT1), peroxisome proliferator-activated receptor gamma co-activator-1alpha (PPARGC1A), and ATP-binding cassette subfamily G (white) member 2 (ABCG2). Allelic frequencies for these 6 markers, and their association with 21 phenotypes, were evaluated in 2 crossbred beef cattle populations that sample influential industry sires. Five of 6 markers were segregating in beef cattle populations; the exception was ABCG2. The SPP1 marker was associated with yearling weight (P = 0.025), live weight at slaughter (P = 0.016), postweaning ADG (P = 0.007), and HCW (P = 0.007) in a large, multisire population representing the 7 most populous beef breeds in the United States. Postweaning growth trait associations were confirmed in an independent population of similar construction, including sires from tropically adapted breeds. The SPP1 marker was associated with yearling weight (P = 0.034), live weight at slaughter (P = 0.011), and postweaning ADG (P = 0.015) and showed a trend toward association with HCW (P = 0.083) in this population. Whereas DGAT1, GHR, and CSN1S1 polymorphisms showed association with some traits in individual populations, the lack of consistent predictive merit between populations indicates they may not be suited for beef cattle selection. No significant associations were observed for the PPARGC1A marker and any of 21 recorded traits, indicating this marker had no apparent value in selection for the beef cattle traits tested in these populations. The SPP1 marker had consistent associations and effect sizes (10.5 to 11.5 kg of live weight at slaughter) in both populations, providing strong evidence for utility of the SPP1 marker for postweaning growth in beef cattle.     

The Location and Suburbanization of Business and Professional Services in the Atlanta Area

Despite an increase of 200,000 jobs in business and professional services in the Atlanta metropolitan area between 1982 and 1997, the central city saw employment as a percentage of these services drop by approximately 20 percent. Most growth occurred in the northern suburbs, resulting in a dispersed distribution of business and professional services in Atlanta. To understand the spatial distribution and suburbanization of business and professional services in Atlanta, regression analysis was carried out for 1982 and 1992. Flexible female workers, corporate headquarters, well –educated professionals, and highway access turned out to be important location determinants, with the latter two being increasingly responsible for the suburbanization of business and professional services.     

Electron capture gas chromatographic determination of thiabendazole in yams

A method for the determination of thiabendazole in yams is reported. The method consists of extracting the chopped crops with ethyl acetate followed by distilled water wash and liquid liquid extraction of the chemicals into dilute hydrochloric acid. The sample is further cleaned up by making the aqueous acidic fraction alkaline and repartitioning into ethyl acetate. The determination step includes evaporation of the cleaned up extract to dryness, derivatization with pentafluorobenzoyl chloride, and determination of the derivatized thiabendazole in acetone by gas chromatography with electron capture detection.     

The reproductive biology and genetic diversity of Potamophila parviflora R. Br.

Potamophila parviflora, a wild relative ofdomestic rice, is endemic to the north-eastern river systemsof New South Wales, Australia. It is the only member of the genus,and is habitat specific. Several new sites were found, mostly in theUpper Clarence catchment. Florets of P.parviflora were found to be 86%female-only, while 14% contained mature malereproductive parts, which occurred more often in the middle sectionof the panicle. Pollen was found to be necessary for the developmentof mature fruits. RAPD data showed that there is very little geneticvariation between individual plants, or between differentpopulations. An embryological study showed several irregularities inmegasporogenesis and megagametogenesis. No tetrads were observed inmegasporogenesis and the ovule is vacuolate at the megaspore mothercell stage. Megagametogenesis proceeded rapidly, nuclei within theovule were sometimes not spherical and varied in size, and sometimesthe antipodal cells doubled in number with a corresponding halving insize of the nuclei. Chromosome number varied between 2n = 24and 2n = 25, between and within populations. These resultsindicate that P. parvifloracould be a diplosporous apomict of the Antennaria type, althoughfurther works are required to provide conclusive proof.     

Identification of 1,8-dihydroxynaphthalene melanin in Monosporascus cannonballus and the analysis of hexaketide and pentaketide compounds produced by wild-type and pigmented isolates of the fungus

Monosporascus cannonballus causes root rot and vine decline in muskmelons and watermelons. Wild types of this fungus often undergo degenerative changes that have been associated with yellow to brown pigmentation, hypovirulence, dsRNA infection, and decreased production of perithecia. In this study, degenerate isolates that produced yellow to brown pigments and no perithecia were obtained from wild-type cultures that had been stored for extended periods of time. Cultures of the degenerate isolates were found to accumulate five related hexaketides when grown on potato-dextrose agar (PDA). In contrast, these hexaketides were present only in minute amounts in wild-type cultures unless grown on NaCl-amended PDA. 1,8-Dihydroxynaphthalene melanin was established to be present in wild-type M. cannonballus and absent in the degenerate isolates. Various melanin-related metabolites, however, were produced by the variants. Tricyclazole in PDA cultures blocked melanin biosynthesis by the wild types but had little effect on hexaketide production by the degenerate isolates.     

Soldier determination in ants: new role for juvenile hormone

Topical application of juvenile hormone analog induces soldier development in the ant Pheidole bicarinata. Soldier induction takes place if the juvenile hormone analog is present during a period of sensitivity that occurs during the last larval instar. Control of worker dimorphism seems to be accomplished through control of timing of metamorphosis. The smallest size at which metamorphosis can be initiated is shifted upwardfrom 1.2 to 1.7 millimeters by exposure to the juvenile hormone analog during the sensitive period.