Reproductive efficiency

Whether the husbandry of the production system is being efficiently carried out, and how much scope there is to increase reproductive efficiency in the sheep flock, for instance, by reducing the number of barren ewes and by reducing the number of lambs lost before sale. 

The advisability of using certain antibiotics, particularly penicillin and tetracycline, in animal feeds has been questioned because of their use in human medicine. Any use of an antibiotic that is prescribed for humans presents some risks to human health, whether the use is for humans, animals or for other purposes but. the uses also have benefits. Otherwise, they would not persist. Antibiotics are used in animal feeds to increase animal weight, increase efficiency of feed utilization, increase reproductive efficiency and decrease morbidity and mortality. These benefits to animals and animal producers are reflected in decreases in food costs to humans. There are also benefits to human health from use of antibiotics in food animals. By reducing the incidence of animal health problems, use of antibiotics in food animals reduce the transference of animal infections to humans. The contention that the effectiveness of penicillin and tetracycline for use in human medicine is rapidly diminishing as a result of the proliferation of resistant bacteria caused by subtherapeutic use of antibiotics in animal production is not supported by experimental data. Rather, the evidence suggests that a fairly stable level of resistance of the intestinal bacteria in humans has long since been established to penicillin and tetracycline as it has been in animals. 

In earlier publications we have shown that the principle of selection can be deduced from the premises of a self-replicating system as an extremum principle. It states that inherent linear autocatalysis causes the relative population numbers to take on values that correspond to the highest reproductive efficiency of the system as a whole. The distribution of relative concentrations in the stationary population is, after a short induction period, independent of changes of the system as a whole. The population consists of a uniquely defined wild-type (or several equivalent,... 

In real life , humans and animals can be exposed to some toxicants both pre- and postnatally. Many organic xenobiotics have the potential to bioaccumulate within exposed individuals, possibly affecting future generations by way of genetic and epigenetic effects. However, reproductive endpoints, such as conception rates and sperm counts, are relatively insensitive, and subtle, toxicant-induced changes in reproductive efficiency can be overlooked or missed (Evans, 2007). 

In [Cu2] a is called the reproductive efficiency of the organism, since it is a ratio of the fraction of energy derived from uptake that is allocated to reproduction to the conversion factor relating food units to weight for reproduction (w/ is the amount of nutrient needed to produce one offspring). For similar reasons, 0 is called the growth efficiency of the organism. 

Despite its slightly different scaling, our /x agrees with the fx in [Cu2]. Cushing calls fx the physiological efficiency coefficient of the population, since it reflects both the reproductive efficiency and the growth efficiency of the organism. 

Bennetau-Pelissero, C., B.B. Breton, B. Bennetau, G. Corraze, F. Le Menn, B. Davail-Cuisset, C. Helou and S.J. Kaushik. Effect of genistein-enriched diets on the endocrine process of gametogenesis and on reproduction efficiency of the rainbow trout Oncorhynchus mykiss. Gen. Comp. Endocrinol. 121 173-187, 2001. 

Many chemicals pose serious risk to humans and to the ecosystem if not controlled. Many VOCs are within this group, and are regulated within the National Emissions Standards for Hazardous Air Pollutants (NESHAP). They often are carcinogens at low exposure levels, impact reproduction efficiency and fetal development, or yield serious injury or death upon even slight exposure. A current list of such pollutants is located under Section (b)(1) at the EPA site, http //epa.gov/ air/caa/caal 12.txt. 

TOXICITY growth inhibition algae (Scendesmus acutus) 500 pg/L in freshwater ECjo (Daphnia) 0.1 ppm, reproduction efficiency... 

The microfluidic systems can enhance assisted reproduction efficiencies. The flow rate affects the cellular behavior of myoblasts, as well as differences in cell density of undifferentiated myoblasts and differentiation patterns. Shear stress brings some effects on hepatocyte activity. The shear flows cause hepatocytes to change morphology and functions according to their exposed value of shear stress. The metabolic activities of hepatocytes under higher shear stress are lower. Morphologic observation reveals that hepatocytes change their shape like vascular endothelial cells do [7]. 

Dunn T G and Moss G E 1992 Effects of nutrient deficiencies and excesses on reproductive efficiency of livestock. Journal of Animal Science 70 1580. 

The switch from good-of-the-species arguments to the "selfish gene paradigm (6) has revolutionized research on animal behavior and reproduction. Now rather than expecting members of a species to cooperate so as to increase overall reproductive efficiency for the species, individuals are expected to do whatever... 

Roche, J.E, 2006. The effect of nutritional management of the dairy cow on reproductive efficiency. Anim. Reprod. Sci. 96, 282-296. 

Renema, R.A., F.E. Robinson, and M.J. Zuidhof, 2007. Reproductive efficiency and metabolism of female broiler breeders as affected by genotype, feed allocation, and age of photostimulation. 2. Sexual maturation. Poult. Sci. 86, 2267-2277. 

One of the crucial points in the area of production animals is to optimize the reproductive efficiency to improve the economic return of livestock [12]. For example, an ideal animal production system for cows requires one calf per cow per year. To achieve this aim, the reproduction time is limited to one or two months. This is due to the gestation period lasting 284 days. Therefore, subtracting the 284-day gestation period from 365 days, females should be pregnant again at 81 days... 

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