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One of the fundamental questions in evolutionary biology is how natural selection and sexual selection mold phenotypes, and the resulting functional capacities of those phenotypes. Strong selection within animal populations is well-documented (Endler 1986; Brodie et al. 1995; Kingsolver et al. 2001) and recent reviews point toward ‘wholeanimal performance’ as being central to understanding thes...

Enzymes have been used for decades to improve the utilization of swine and poultry diets. For instance phytase, amylase, ß-glucanase and xylanase are added to the cereal-based diets of such monogastrics to increase the utilization of dietary phosphorous, starch, ß-glucans and arabinoxylans respectively. For many years, researchers were discouraged from using enzymes to enhance the utilization o...

Abstract We consider the problem of estimating the distribution of carcass weights in a flock of animals from estimates made on a truncated sample. This arises when a farmer chooses the heaviest lambs for slaughter and then measurements are made by the meat processor. This enables a farmer to answer two questions: what proportion of the animals remaining exceed a nominated carcass weight, and/o...

the study investigates factors that affect members' satisfaction of mashhad cattle husbandry cooperatives. the required data and information were collected via interviews and questionnaires from cattlemen. cattlemen of mashhad constitute the statistical population of the study. using cochran formula, 60 cattlemen were selected randomly as the sample in 2013. spss software package was used to an...

rumen is a persistent and specific ecosystem consists of bacteria, protozoa and fungus where feed fermentation takes place in it. produced hydrogen in rumen can be used in the synthesis of the volatile fatty acids and the microbial protein and its excess would be eliminated through the production of methane by methanogenesis. nutritionists have tried to find ways to decrease loss and energy and...

economic data and performance records from 10 iranian holstein dairy cattle herds, as well as milk production and fertility records from iranian center of animal breeding and animal production improvment were used to estimate the effect of calving difficulty on milk production, fertility and as well on the economic aspects of maternal and direct calving difficulty. calving difficulty could be d...

Thiamine deficiency causes a decrease in transketolase activity and an increase in thiamine pyrophosphate (TPP) effect on the erythrocytes. The objective of this experiment was to determine if ruminal acidosis alters erythrocytic transketolase enzyme activity as an indicator of thiamine level in feedlot cattle. A total of 65 feedlot cattle (1–2 years old) were fed either high concentrate diet (...

Feed efficiency has a major influence on the unit cost of beef cattle production. Gibb and McAllister (1999) have reported that a 5% improvement in feed efficiency has an economic impact four times greater than a 5% improvement in average daily gain. In addition, the cost of feed is second only to fixed costs in importance to the profitability of commercial beef operations (Basarab, 1999). The ...

Dairy producers have a difficult task when attempting to assess the possible exposure of their animals to mycotoxins. Information gleaned from the scientific literature suggests signs and symptoms for toxins which may actually not be likely to appear in a herd. Also, that same literature suggests concentrations at which the toxin exerts its effects. Those concentrations may have little meaning ...