Laying hen rearing systems have been the focus of scientific research for many years. Over the last few decades, new laying hen rearing systems have been rapidly introduced in an effort to harmonise poultry health and welfare with consumer, producer, industry and environmental demands. Given the above situation, the subject matter of this paper was a comparative review of the results obtained by different authors on the effect of rearing system on productive traits (egg production and mortality) and egg quality characteristics (egg weight, proportions of main egg parts, Haugh units, yolk colour and carotenoids) in laying hens. Although productive performance in alternative systems is often lower compared to conventional, intensive layers, eggs from alternative systems have been proven in numerous studies to have better nutritional properties. Moreover, research results indicate differences within rearing systems. In view of this, this overview of the literature on the use of different rearing systems in table egg production can serve as a tool in determining the future direction of research as well as an indicator of its practical application.
Enzyme supplementation of poultry diets is nutritionally, economically and environmentally justified. Enzymes are used to increase the energy value of feed ingredients and enhance the utilisation of protein, fats, carbohydrates and phytin phosphorus from plant materials, leading to a lower excretion rate of undigested nutrients into the environment and, hence, reduced environmental pollution. This is especially important regarding proteases, as the correct digestion of nitrogenous compounds in feed materials is essential for reducing N excretion -a major pollutant worldwide. Numerous studies have shown no adverse effects of enzyme supplementation in broiler diets on body weight, mortality, health, feed intake, FCR, nutrient digestibility, meat quality and production costs. However, there is still a large amount of uncertainty regarding the use of enzymes.
As generally known, broiler meat quality is a very complex issue that can be looked at from several aspects. In terms of the meat processing industry and consumers' interests, fattened chicks should be characterised by good dressing percentage, desired conformation, as much meat on the carcass as possible, optimal distribution of fat tissues, appropriate skin colour and least damage possible occurring during fattening, loading and unloading. With respect to that, the proportions of major basic carcass parts (breast, drumstick and thigh) as well as the presence of certain tissues in them are regarded as vital parameters determining broiler meat quality (Lewis et al., 1997;Sütö et al., 1998;Holcman et al., 2003;Ristic, 2003). The above-mentioned quality traits depend on a number of factors. Of the biological ones, the greatest impact is produced by genotype, sex and age (Lewis et al., 1997;Bokkers and Koene, 2003;Hellmeister et al., 2003).Among numerous non-genetic factors that may have a considerable effect on meat quality, a broiler rearing system has been recognised over the past years by a large number of authors as being particularly important (Lewis et al., 1997;Bokkers and Koene, 2003;Hellmeister et al., 2003;Ristic, 2003). ABSTRACT:The objective of this study is an analysis of meat quality in broilers of standard fast-growing hybrid Hybro G, reared in two different non-industrial systems (extensive rearing in a poultry house or "extensive indoor" system and rearing in a poultry house using a free range or "free-range" system). Quality parameters, i.e. proportions of basic carcass parts (breasts, drumsticks and thighs), abdominal fat, and proportions of basic tissues (muscles, bones and skin) in more valuable carcass parts, were investigated. The aim of the investigation was to analyse the effect of the two non-industrial rearing systems and broiler sex on the above-mentioned traits of broiler meat quality. The used rearing systems (free-range and extensive indoor ones) did not have a statistically significant effect on the proportions of major basic carcass parts and of abdominal fat in broiler chickens (P > 0.05). Heavier carcasses at slaughter (on the 56 th day of fattening) were recorded in the male broilers compared to the female ones, the differences being statistically significant (P < 0.01). The drumstick proportion in the male broiler carcasses was statistically significantly higher (P < 0.05) than the proportion in the female broilers. The interaction between the investigated effects (of sex and rearing system) did not exert a statistically significant effect on the proportions of major basic carcass parts and abdominal fat in broiler chickens (P > 0.05). The rearing system (free-range and extensive indoor) and the interaction between the investigated effects (of sex and rearing system) did not affect statistically significantly the differences expressed in the meat, skin and bone proportions in breasts, drumsticks and thighs of the broilers (P > 0.05). The sex effect on the skin proportions in b...
The aim of this study was to evaluate the effect of rearing system and hen's age on quality and chemical composition of eggs. The tested rearing systems were: cage, floor and organic (30 birds Isa Brown hybrid per group). Fifteen eggs per group were collected for analyses in each of three phases of the productive cycle (32, 48 and 72 weeks hen's age). In these samples were investigated external (egg weight and egg shape index), internal (albumen height, Haugh unit and yolk colour) and chemical composition of eggs (dry matter, minerals, protein and lipids content). The general conclusion is that the egg weight and Roche values were increased, while egg shape index, albumen height and Haugh unit were decreased with hen's age. Organic eggs had higher albumen height and more Haugh units in the 48 and 64 weeks compared to the floor and cage eggs. Yolk colour of the floor and cage hens most dependent on the hen's age, on the other hand-yolk colour of organic hens most dependent on the grass availability at the outlet. Eggs from the organic rearing system had a lower dry matter, proteins and lipid content as compared to the cage system.
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