this study was carried out to investigate the possibility of prediction the occurrence of heat stress in dairy cows and determination of climate critical periods. the most common indexes for estimation the degree of thermal stress istemperature humidity index (thi). in this study yousef’s thi index (1985)was used to analyze the yearly and monthly effects of temperature and humidity. meteorologi...

Exploited ecosystems are characterised by exports of secondary production from each fished trophic level that reduce the energy available for upper levels at ecosystem scale thus impinging on overall secondary productions. Depletion in secondary production with respect to the unfished state is here proposed as a proxy for quantifying ecosystem effects of fishing. Theoretical analysis of trophic...

Procedures for selecting sires are compared in terms of making maximum genetic progress in economic lnerit. A quadratic index, a simplified form of the quadratic index and a linear index to evaluate economic merit, and a restricted index to improve milk as much as possible while holding milk fat percentage constant, all result in nearly equal expected genetic progress in economic merit. Selecti...

First rotation Pinus radiata D. Don trees were grown on a nitrogen-deficient sand dune in an experimental design that included lupin (Lupinus arboreus Sims) as an understory species, and biennial application of balanced fertilizer in a replicated split-plot factorial design with thinning treatments as subplots. From an initial 2222 stems ha(-1), stands were thinned to 1483 and 741 trees ha(-1) ...

We analyze in detail photon production induced by a superluminal refractive-index perturbation in realistic experimental operating conditions. The interaction between the refractive-index perturbation and the quantum vacuum fluctuations of the electromagnetic field leads to the production of photon pairs.

The need to accelerate the selection of crop genotypes that are both resistant to and productive under abiotic stress is enhanced by global warming and the increase in demand for food by a growing world population. In this paper, we propose a new method for evaluation of wheat genotypes in terms of their resilience to stress and their production capacity. The method quantifies the components of...

A multitrait selection index (I T ) for Zimbabwean Jersey cattle was constructed. The breeding objective was defined in terms of production and functionality traits. The production component of the index included milk yield (M), butterfat yield (F), protein yield (P), butterfat percent (F%), and protein percent (P%), while the functional component included the somatic cell count (SCC). The inde...

This study sets out to verify the key predictors of the dynamics of the arable production per capita index, the arable production and permanent crop land and forest area at a national scale in Cameroon. To achieve this objective, data for twelve time series data variables spanning the period 1961-2000 were collected from Oxford University, the United Nations Development program, the World Bank,...

Multiple-trait selection indexes should include all of the economically-relevant traits that influence the profitability of beef cattle production. They provide an economic evaluation of the genetic differences among sires, and an objective way to determine likely differences in the profitability of progeny from different sires. In contrast to the swine, poultry, sheep, and dairy cattle industr...