the objective of this study was to evaluate effect of different concentrations of catalase in two extenders on motility, viability and lipid peroxidation bull spermatozoa during semen freezing process. thirty ejaculates collected from ten holstein bulls were pooled and evaluated at 37 °c. pool ejaculated was split into two main experimental groups, 1 and 2. in experiment 1, specimen was diluted...

—The management and recovery of populations of bull trout Salvelinus confluentus requires a comprehensive understanding of habitat use across different systems, life stages, and life history forms. To address these needs, we collected microhabitat use and availability data in three fluvial populations of bull trout in eastern Oregon. We evaluated diel differences in microhabitat use, the consis...

As apex predators, sharks play an important role shaping their respective marine communities through predation and associated risk effects. Understanding the predatory dynamics of sharks within communities is, therefore, necessary to establish effective ecologically based conservation strategies. We employed non-lethal sampling methods to investigate the feeding ecology of bull sharks (Carcharh...

ity of a beef operation is the percentage of the calf crop weaned, which, in turn, is determined mainly by the number of cows bred during the breeding season. The herd bull influences overall herd fertility more than any other single animal. Because the bull also supplies half of the genetics to all of the calves he sires, bull selection can be the most powerful method of genetic improvement in...

BACKGROUND Predators can impact ecosystems through trophic cascades such that differential patterns in habitat use can lead to spatiotemporal variation in top down forcing on community dynamics. Thus, improved understanding of predator movements is important for evaluating the potential ecosystem effects of their declines. METHODOLOGY/PRINCIPAL FINDINGS We satellite-tagged an apex predator (b...

In this paperwe testwhethermean reversion in stockmarket prices presents a different behavior in bull and bear markets. We date the US bull and bear periods using Bry and Boschan (1971) algorithm. We examine the order of integration in the S&P 500 stock market index covering a daily period from August 1929 to December 2006 in bull and bear phases. Our results indicate the existence of different...

Fertility in a bull is generally defined as the ability to impregnate females. Certainly that is a minimum requirement, but a bull with high fertility is able to impregnate more than the expected number of cows in a short breeding season. Such a bull has greater economic value than one of lesser fertility (1,17). If the bull also has a desirable genetic background, it could contribute more than...

A post-pubertal bull on an artificial insemination station was found to be persistently shedding bovine viral diarrhoea virus (BVDV) in semen over a period of eleven months, while demonstrating no viraemia. Circulating antibodies to BVDV were consistently high, suggesting that the immune system was challenged repeatedly. Post-mortem findings confirmed that the virus was sequestered in the teste...

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This paper considers a variety of econometric models for the joint distribution of stock and bond returns in the presence of regime switching dynamics. While simple twoor three-state models capture the univariate dynamics in bond and stock returns, a more complicated four state model with regimes characterized as crash, slow growth, bull and bull burst states is required to capture the joint di...