Effects of Housing Systems on Biochemical Indicators of Blood Plasma in Laying Hens

Pavlik A. , M. Pokludova, D. Zapletal, P. Jelinek: Effects of Housing Systems on Biochemical Indicators of Blood Plasma in Laying Hens. Acta Vet. Brno 2007, 76: 339-347. The aim of this study was to compare biochemical indicators of blood plasma of laying hens housed in three different housing systems (conventional cage system, enriched cage system and deep litter system). In each housing system, 12 ISA Brown laying hens were observed during the laying period from week 22 to 75 of age. Blood samples for determination of biochemical indicators in plasma were collected during this period in week 22, 47 and 75. Indicators of blood plasma metabolic profi le of laying hens of all monitored groups during the laying period ranged in intervals stated for healthy animals. In some cases, signifi cant differences between housing systems were found, however, these differences do not give clear evidence of the infl uence of the housing system on the health of animals. The differences were apparently due to different effi ciency of each group during the laying period. Housing system, blood, total protein, glucose, cholesterol, uric acid, alkaline phosphatase Public concerns about the welfare of laying hens resulted in minimum welfare directives in the European Union, with the imposing of a ban on conventional cages in 2012 (European Commission, 74/1999). Since then, cages are allowed only if enriched with nests, perches, and dust baths, i.e. facilities that improve the behavioural repertoire of the birds (Wall and Tauson 2002). Group size has been shown to have a signifi cant effect on production traits. The general trend in layer strains is higher mortality, more feather and skin damage, and lower egg production as group size increases (Tauson 1998; Bilcik and Keeling 1999). The conventional cage was the most common housing system in Europe because of the advantages of more disease-free birds, allowing e.g. the prevention of coccidiosis (Appleby and Hughes 1991), and less bird aggression and cannibalism (Abrahamsson and Tauson 1995). Smaller group sizes consisting of 6 hens or less are associated with easier bird inspection and cleaner eggs (Bell and Adams 1998), and are economical (van Horne et al. 1998; Appleby et al. 2002) compared with alternative housing systems such as deep litter technology. Enriched and modifi ed cages for small groups of hens seem more realistic as alternative systems in large-scale production than deep litter systems, in which birds are kept in larger groups (Tauson 1998). De Boer and Cornelissen (2002) consider the battery cage system, particularly from the perspective of production and several health indicators, to be more benefi cial than the aviary systems. Determination of the indicators of internal environment is one of the methods of evaluating the effect of the factors of housing environment on health and production of farm animals. It provides valuable information about relations between the internal environment of the organism, nutrition, age and performance. It contributes to an objective ACTA VET. BRNO 2007, 76: 339-347; doi:10.2754/avb200776030339 Address for correspondence: Ing. Ales Pavlik, Ph.D. Department of Animal Morphology, Physiology and Genetics Mendel University of Agriculture and Forestry Zemědělska 1, 613 00 Brno, Czech Republic Phone: +420 545 133 148 E-mail: pavlik@mendelu.cz http://www.vfu. cz/acta-vet/actavet.htm evaluation of functional and health condition and helps to discover and to diagnose animal diseases (Kredatus and Valent 1993). The changes in the content of total protein correlate closely with the metabolic changes in the animal organism, and refl ect various disorders of nutritional character, the cause of which is either insuffi cient or excessive intake of proteins in feed mixtures. The level of blood plasma glucose is maintained at a relatively stable level with highly sensitively controlled homeostatic mechanisms. The level of glycaemia changes in the course of growth and maturation, depending on the intake of feed, production performance as well as in relation to the change of the environment (Nasreldin et al. 1988). Cholesterol has a proven relationship with the metabolism of bile acids, sexual hormones and other steroid substances (Griffin 1992). The effect of the age of laying hens also contributes during changes of cholesterol concentration (Suchý et al. 1995, 1999). Uric acid level fl uctuates depending on the intake of purines and its increased amount in blood often accompanies the symptoms of gout. Its concentration increases with elevated temperature in the environment (Koelkebeck and Odom 1995). Determination of the alkaline phosphatase (ALP) activity is one of the most important clinical and biochemical examinations during the monitoring of the metabolic profi le of the hens’ blood. Materials and Methods Animals and breeding conditions The experiments were performed on ISA BROWN pullets, kept in a hall with deep litter. The available area, complete feeding mixture, light-dark (L : D) cycle, housing temperature, relative air humidity changed according to technological instructions for ISA BROWN pullets. During the rearing period standard vaccinations were provided. At the age of 15 weeks, they were randomly divided into 3 of the following housing systems: conventional cage housing system four-fl oor, total (available) area 550 cm2/bird (2 birds kept on 1120 cm2 – 32 × 35 × 45 cm), 2 nipple drinkers, belt feeder 15 cm/bird, device for claw shortening, enriched cage housing system according to Council Directive 99/74/EC three-fl oor, total area 945 cm2/bird (8 birds kept on an area of 7 560 cm2 180 × 42 × 45 cm), available area 643 cm2/bird, 6 nipple drinkers, belt feeder 20 cm/bird, nest (30 × 35 × 45 cm), perching area 15 cm/bird, devices for dust bathing and scratching, device for claw shortening, deep litter housing system available area 2 000 cm2/bird (20 birds kept on an area of 40 000 cm2 200 × 200 × 180 cm), tube feeder 5 cm/bird, round drinker 2 cm/bird, deep litter made from wood shavings. All of the housing systems were situated in the same building with central system of ventilation and temperature regulation. For each system, experimental group consisting of 12 birds was established with the mean body weight of 1 300 50 g. Throughout the study, the hens were fed using a complete feeding mixture for laying hens containing 875 g·kg-1 of dry matter, energy content MEN 11.1 MJ·kg -1, content of crude protein 170.7 g·kg-1, Ca 35.9 g·kg-1 and P 6.3 g·kg-1. A constant light-dark (L : D) cycle (15 : 9, switching on at 4.00 h, switching off at 19.00 h) was maintained in all three systems as recommended in technological instructions for ISA BROWN hens. The temperature of housing was in the range of 18 to 22 °C; relative air humidity ranged from 65 to 70%. No red mite or other parasite or viral infection was presented during experimental period. Collection of blood samples Blood samples (3 ml) of all hens in experimental groups were collected from a brachial vein of hens at the age of 22, 47 and 75 weeks, always between 7.00 and 8.30 h. EDTA was used as anticoagulant. Blood samples were centrifuged and the separated plasma was stored at -20 °C until analyzed. Blood sampling was performed randomly in hens kept in conventional, enriched and deep litter system. Egg production and body weight Next to the determination of plasma metabolite levels, the body mass of the animals and the egg production were evaluated. The egg production was recorded weekly during the laying period and it was expressed in percentage as laying intensity. The individual body weight of laying hens was determined at the beginning of the laying period and in weeks 22, 47 and 75. Measurement of biochemical indicators Blood plasma was also subjected to the following biochemical tests: total protein, glucose, cholesterol, uric acid and alkaline phosphatase. Analyses were provided photometrically with commercially available kits Bio-LaTests made by Pliva-Lachema, a.s. , Czech Republic, on COBAS MIRA S analyzer (Roche). Statistical evaluation The data are expressed as means ± SEM. Changes in egg production were analyzed by One-way ANOVA for factor housing system. Changes in biochemical indicators and body weight were analyzed by repeated measures 340