Effect of testosterone propionate on performance and carcass characteristics of heifers and cows

Two experiments were conducted to evaluate the effect of testosterone on growth and composition of cattle. In the first experiment, crossbred yearling heifers (n = 48) were assigned to four treatments: 1) control (no implant), 2) Synovex-H implants on d 1 and 84, 3) one testosterone propionate implant administered on d 1 and a second on d 84 and 4) two testosterone propionate implants administered on d 1. Heifers were fed a high-energy diet for the 157-d study. Implanting with the high-testosterone treatment improved (P less than .05) daily gain and feed efficiency compared with the other treatments. Marbling score was reduced (P less than .05) with the high-testosterone treatment. In Exp. 2, mature cows (n = 36) were assigned to one of three feeding periods (0, 42, or 84 d) with the cows fed 42 or 84 d subdivided into two groups (implanted with testosterone propionate or nonimplanted control). Cows were fed a high-energy diet and slaughtered at the end of each feeding period. Testosterone did not influence (P greater than .05) feedlot performance. Increased time on feed reduced (P less than .01) daily gain (live weight basis) and feed efficiency but did not influence feed intake. Testosterone treatment had little influence on the fat and moisture contents of the carcass soft tissue or on the palatability characteristics of loin steaks. Time on feed increased lean muscle mass and carcass fat (P less than .05). Sensory traits were improved at 42 d on feed (P less than .05), but no further sensory improvement was observed at 84 d.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of male accessory gland secretions on sensitivity of porcine sperm acrosomes to cold shock, initiation of motility and loss of cytoplasmic droplets

Hyaluronidase release was used as an index of acrosomal membrane damage during cold shock of epididymal boar sperm and ejaculated sperm from intact and vesiculectomized boars. Sperm were also incubated with seminal plasma from intact and vasectomized boars to examine the contributions of male accessory gland secretions. Acrosomal membranes of epididymal sperm were more resistant to cold shock than those of ejaculated sperm. Only 36% of the hyaluronidase released by ejaculated sperm was released by the epididymal sperm in spite of similar hyaluronidase content of the sperm. Preincubation of epididymal sperm in seminal plasma from both intact and vasectomized boars increased resistance to cold shock by 60 to 80%. Initial dilution of epididymal sperm with seminal plasma, rather than Ringer-fructose buffer, was associated with low progressive motility and with retention of cytoplasmic droplets. In contrast, acrosomal membranes of ejaculated sperm from intact and vesiculectomized boars exhibited similar sensitivity to cold shock, releasing hyaluronidase capable of forming .20 and .19 mumol N-acetylglucosamine from hyaluronic acid/10(8) sperm in 8 min. Moreover, seminal plasma from vasectomized boars had no effect on acrosomal sensitivity to cold shock of ejaculated sperm from vesiculectomized boars.     

Effects of data structure and selection on estimated inbreeding depression in experimental Tribolium castaneum lines

SUMMARY: Inbreeding depression was estimated for four experimental Tribolium castaneum lines. Each line, containing approximately 7000 animals, was selected for 16 generations either randomly (control), on pupae weight (PWT), on family size (FST) or on an index containing both PWT and FST. The inbreeding trend was 0.9, 0.5, 0.5 and 0.4 % inbreeding per generation in PWT-selected, FST-selected, index-selected, and control line, respectively. The model used to estimate the inbreeding depression included a linear regression on individual inbreeding coefficients, and random additive genetic effects. Using all the performance and pedigree data, estimated inbreeding depressions in the control line were -0.13 (SE = 0.16; #) and -8.50 (SE = 2.66; μg) per 1 % inbreeding for FST and PWT, respectively. Using only performance data of the latest generation in the control line, the estimated inbreeding depressions changed considerably: -0.17 (SE = 0.82) and -37.4 (SE= 11.9) for FST and PWT, respectively. Estimated inbreeding depression for FST in the FST-selected line was - 0.40 (SE = 0.31). Inbreeding depression for PWT in the PWT-selected line was 21.6 (SE = 25.8). This study indicates that estimating inbreeding depression might best be based on the performance data of animals with an equal and sufficiently-large number of ancestral generations known. ZUSAMMENFASSUNG: Wirkung von Datenstruktur und Selektion auf gesch?tzte Inzuchtdepression in experimentellen Triboleum castaneum Linien Jede der vier experimentellen Linien, aus je etwa 7000 Individuen, wurde durch 16 Generationen selektiert, zuf?llig die Kontrolle, auf Puppengewicht (PWT), Familiengr??e (FST), oder auf einen beide Merkmale kombinierenden Index. Inzucntzuw?chse in diesen vier Linien waren 0.4, 0.9, 0.5 und 0.5% je Generation. Das Modell zur Sch?tzung der Inzuchtdepression beinhaltete eine lineare Regression auf individuelle Inzuchtkoeffizienten und zuf?llige additive-genetische Wirkungen. Aus allen Daten, Leistung und Pedigree, ergaben sich -0.13 (SE = 0.16; #) und - 8.5 (SE = 2.66; mg) je 1% Inzucht für FST und PWT, Daten der letzten Generation ergaben deutlich andere Werte: -0.17 (SE = 0.82) und -37.4 (SE = 11.9) für FST und PWT. Inzuchtdepressionen für FST bzw. PWT in den jeweils hierfür selektierten Linien waren -0.40 (SE = 0.31) und 21.6 (SE = 25.8). Es wird gefolgert, da? Sch?tzungen auf Leistungen von hinreichend gro?er Zahl von Vorfahrengenerationen beruhen sollten.     

Detection of Xylophilus ampelinus in grapevine cuttings using a nested polymerase chain reaction

A sensitive and specific assay was developed to detect bacterial blight of grapevine caused by Xylophilus ampelinus (Panagopoulos, 1969) comb. nov. in grapevine cuttings. The 16S−23S rDNA intergenic spacer region of X. ampelinus was sequenced and pathogen-specific primers were designed from a region in the spacer between the tRNA (Ala) and the 23S genes. A nested PCR (n-PCR) reaction was applied with a first-stage PCR using universal primers within the ends of the 16S and 23S genes, followed by a second-stage PCR with nested primers specific to the X. ampelinus spacer region. A 277-bp fragment was amplified from 38 Xylophilus strains tested, but not from saprophytes associated with grapevine or phylogenetically related phytobacteria. The 277-bp product was shown to be derived from the X. ampelinus spacer region by restriction with Dra I, Sau 3AI, Taq I and Msp I, Southern hybridization and genomic DNA dot blots. When the (n-PCR) procedure was applied in the absence of nontarget DNA, the limit of detection was less than 10 colony-forming units (CFU) per µ L. The same number of  X. ampelinus CFU could be detected in the presence of 1·5 × 10⁵ CFU  µ L⁻¹ of Erwinia herbicola cells using the n-PCR procedure.     

<Emphasis Type="Italic">Cercospora zeina</Emphasis> is the causal agent of grey leaf spot disease of maize in southern Africa

The aim of our study was to identify the causal agent of grey leaf spot disease of maize in southern Africa. Single-conidial cultures were recovered from maize leaves with typical disease symptoms sampled from several fields in South Africa, Zambia and Zimbabwe. Morphology, cultural characteristics, and a PCR-based test using Cercospora zeae-maydis and C. zeina-specific primer sets identified all single-conidial cultures as C. zeina. In addition, sequence alignment of DNA fragments of the internal transcribed spacer region (ITS1, ITS2, and the 5.8S gene) and elongation factor 1-α grouped all cultures in the same clade as the C. zeina ex-type culture CBS 118820. To by-pass cultivation of the slow-growing fungus, a rapid method to isolate DNA directly from lesions was successfully applied for PCR identification of C. zeina with species-specific ITS and histone primers. Koch’s postulates were fulfilled for C. zeina by artificially inoculating maize plants in a greenhouse, re-isolating conidia emerging from lesions and verifying pathogen identity with molecular techniques. These results provide evidence that confirms the presence of C. zeina and absence of C. zeae-maydis in commercial maize plantations in southern Africa.