Increase in growth rate through genetic selection and improved nutrition in broiler chickens has been associated with high body fat deposition. This is particularly evident under ad libitum feeding that is normally practiced. Excessive fat deposition in the body of broilers is a common problem for poultry producers and consumers. Studies have shown that feed restriction could decrease fat content and increase protein deposition in carcasses, thus resulting in their improved composition. In addition to determining the optimal time to start and the duration of the restrictive nutrition, the success of the given programs largely depends on the intensity of the restriction, as well as the type of applied technique. Considering that in a large number of studies, the application of restrictive programs resulted in a reduction of body fat in broilers, but at the same time the desired body weight was not achieved at the slaughter (market) age, these programs should not be a priori rejected as ineffective. It is necessary to determine whether the market price of the obtained product (poultry meat) with its reduced fat content justifies the lower body weight of broilers achieved at the end of the fattening period.

The aim of this study was to establish incubation values of eggs (egg fertilization, absolute and relative embryo mortality, and hatchability of male and female chicks), morphometric indicators (preincubation egg mass; length, width, and egg shape index; hatched female and male chicken mass and their relative share in the egg mass before incubation), and the phenotype correlation between some traits in the younger parent flock (YF33—33 weeks) and the older flock (OF49—49 weeks) of the light Institut de Sélection Animale (ISA) Brown hybrid. With regard to incubation values, the younger flock (YF33) demonstrated better incubation results than the older flock (OF49). The egg fertilization rate was 95.24 and 94.22%, respectively, chick hatchability as the percentage of the total of incubated eggs was 86.51 and 84.89%, respectively, and chick hatchability as the percentage of the total of fertilized eggs was 90.83 and 90.09%, respectively. Embryo mortality rate was 8.73 and 9.17% (YF33), and 9.33 and 9.91% (OF49). Regardless of the parent flock age, eggs that hatched female chicks had lower values of observed morphometric traits than those that hatched male chicks, except for the egg shape index (77.49–77.47%, respectively) which was higher by 0.02% in eggs which hatched female chicks, but this difference was not statistically significant (P > 0.05). Contrary to effects of the chick sex, the parent flock age had considerably larger effect on observed morphometric traits, as all morphometric indicators of eggs and hatched chicks of both sexes in the older flock (OF59) had statistically significantly higher values (P < 0.001) than in the younger flock (YF33). The only exception is the relative share of the chicken in the egg mass where the measured difference (−0.03%) was not statistically significant (P > 0.05). The phenotype correlation coefficients determined (rp) between the egg mass before the incubation period and the egg shape index were statistically significant (P < 0.01; P < 0001), except between the egg mass of eggs which hatched female chicks and the egg shape index in the young flock (YF33), whereby the calculated coefficient (rxy = 0.107) was not statistically confirmed (P > 0.05). Furthermore, the egg mass and hatched chicken mass of both sexes increased with the age of the parent flock, and statistically significant absolute phenotype correlation (P < 0.001) was determined between these two indicators.

The purpose of this review is to review the current state and achievements in poultry production in Serbia and worldwide, primarily the EU. Particular emphasis is placed on impacts of different rearing system, i.e. housing and fattening, on the production and the quality of the poultry meat and eggs and, simultaneously, on the welfare of poultry and environmental protection according to EU standards. According to the latest available data, total number of poultry produced in Serbia in 2015 was 17,450,000 units and production of meat amounted to around 86,000 t, while consumption was 12.12 kg per person. Egg production in 2015 was approximately 1.7 billion eggs, which is around 202 eggs per hen. A total of 13.1 million tons of poultry meat was produced in EU in 2015. It is evident from the literature that the poultry production in EU and worldwide has undergone significant changes, and clear criteria have been established to improve the quality of the products (meat and eggs), to guarantee the safety of the food, to protect the environment, and to ensure animal welfare in line with the relevant ethic norms. For these reasons, many countries within EU and worldwide, including Serbia, attach importance to housing systems for laying hens, with particular concern for animal welfare. Alternative housing systems (floor, aviary, free range and organic production) are increasingly used in the production of poultry meat and eggs instead of conventional systems. This is because it is considered that alternative housing systems may have positive effect on the productive traits of the poultry and, consequently, on the production of the quality organic meat. Furthermore, it is evident from research that pure (indigenous) breeds and strains are given growing importance in the production of organic meat and eggs in semi-intensive, semi-extensive and even in extensive rearing systems.

Examinations were conducted in two flocks of broiler parents' hybrids Ross 308 and Cobb 500. At the beginning of the production cycle (24th weeks of age) was determined that the average hens body weight of hybrid Ross 308 was 2680.40 g, and to hybrid Cobb 500 was 2697.80 g. At 42nd weeks of age (middle of the production cycle) hens body weight was 3565.10 g (Ross 308) and 3599.05 g (Cobb 500), while at the end of the production cycle (61st weeks of age) hens body weight of hybrid Ross 308 was 3841.50 g, and to the Cobb 500 was 3850.00 g. Determined differences of hens body weight (17.40 g, 33.95 g and 8.50 g) in specific periods of the production cycle, and the difference in hens body weight for the entire cycle (23.26 g) weren't statistically significant (P>0.05). Specific consideration of the impact of hens' body weight on reproductive performances of broiler parents was determined by calculating the coefficients of phenotypic correlation among the tested indicators. Thus, between hens body weight and most reproductive indicators of broiler parents were determined statistically very significant (P<0.001) coefficients of phenotypic correlation, while between hens body weight and the percentages of chickens feasibility from fertilized eggs were determined significant (P<0.001; P<0.01; P<0.05) correlation coefficients for a slightly shorter period than anticipated production cycle.

A 42-day experiment was conducted to compare the effects of various levels of sodium selenite (SS) and Se-enriched yeast (SY) on chicken productivity, carcass traits, and breast Se concentration. Six hundred 1-day-old Cobb 500 broiler chicks were placed on 1 of 6 experimental treatments. The treatments consisted of feeding a diet without Se supplementation (basal diet) or basal diet with 0.6 mg/kg supplemented Se supplied by SS, SY, or a mix of the two (0.45 SS + 0.15 SY; 0.3 SS + 0.3 SY; 0.15 SS + 0.45 SY). Chicks in all Se-supplemented treatments had significantly higher final body weight and eviscerated weight than those on the basal diet (P < 0,05) and no significant differences were observed among selenium source (P < 0.05). Also, chicks in all Se-supplemented treatments had significantly higher Se contents in breast tissue than the control group (P < 0.05). Replacing SS by SY in the broiler diets resulted in increased concentrations of Se in the breast (P < 0.01). Strong correlations were found between breast Se concentrations and the level of SY supplementation of the broiler diet (r = 0.992). The results from this experiment indicate that SY is a superior source of selenium for the production of selenized meat, and can be used, without any detrimental effect on chicken performance, for adding nutritional value to broiler meat and thus safely improving human selenium intake.

A 16-week-long experiment was performed to compare the effect of sodium selenite (SS) and selenium-enriched yeast (SY) supplementation on eggshell quality and also to evaluate breaking force correlation with other parameters of shell quality originating from hens fed with selenium supplementation. One hundred Shaver 579 hens (27 weeks old) with similar body size were randomly divided for five dietary treatments: basal diet without selenium supplementation and basal diets with two levels of selenium supplementation (0.4 or 0.8 mg/kg) via SS or SY. No adverse effect of Se inclusion in hen's feed, regardless of its source, on shell breaking force, shell deformation, shape index, shell thickness and shell percentage, were observed throughout the current study (P > 0.05). Moderate correlations were found between breaking force and nondestructive shell deformation for all diets (P < 0.05). There was no significant overall correlation between egg breaking force and shell thickness or/and percentage shell in the presence of selenium supplemention (P > 0.05). Shape index in all four selenium-supplemented groups was not related to the breaking force (P > 0.05). Selenium supplementation of up to 0.8 mg/kg, regardless of its source, in the diet of laying hens in their first phase of laying does not adversely affect eggshell quality.

The effect of short term calcium deficit in nutrition of young laying hens on production and quality of product was investigated, as well as the effect of the use of large size particles of calcium source on alleviation of the consequences of calcium deficit. Six week investigation was carried out on total of 135 individually monitored layers from age of 23 to 28 weeks, as two-factorial trial with 3 levels of calcium (Ca) in feed (2.5; 3.0 and 3.8%) and 3 different ratios of powder and granulated source of Ca (100:0; 60:40 and 40:60%). Trial was also divided into two three-week periods (period of deficit and period of normalization of nutrition of hens in regard to calcium). During the research production results, incidence of defect eggs and eggshell quality were monitored. Research results showed that use of diets with 2.5 – 3.0% Ca in nutrition of young layers, regardless of the form of Ca source in feed, powder or particles, can have negative impact on productivity of layers and eggshell quality, practically demonstrated in increased incidence of defect eggs, primarily higher incidence of big defect off eggshell, but also decreased laying ability at the end of three week deficit period. Trial groups of layers which in the first part of trial period were exposed to Ca deficit, in the second part demonstrated fast response to normalization of nutrition related to Ca, and in the first week of balanced feeding their egg production and eggshell quality is normalized. Research showed the justification for use of large size marble particles in nutrition of young layer hens, especially in conditions of their nutrition with suboptimal calcium levels, for the purpose of maintaining of the egg shell quality.

The effect of different levels of organic selenium (selenized yeast) on slaughter meat traits of fattening chickens (broilers) was investigated. Trial was carried out on 120 Hybro-PN chickens divided into four groups, in duration of six weeks. All groups of chickens were fed complete mixtures, and selenium was added to the food in the form of selenized yeast in the amount of 0 (I ); 0,3 (II); 0,6 (III) or 0,9mg/kg (IV-group). The highest average values of carcass yield 'conventional processing', 'ready to roast' and 'ready to grill' were recorded in chickens of group III (2059,6, 1851,97 and 1756,45g), with addition of 0,6mg Se/kg, followed by chickens of group II (2048,17, 1841,36 and 1748,57g) and group IV (1957,46, 1764,22 and 1676,05g) with 0,3 and 0,9mg/kg of added selenium, respectively, whereas the lowest values (1835,21, 1660,87 and 1572,61g) were established in chickens of group I without addition of this micro element. Average values of slaughter yields 'conventional processing', 'ready to roast' and 'ready to grill' were approximately the same in chickens of all investigated groups, and established differences showed no statistical significance (P > 0,05). The lowest breast mass was in I group (573,55g), and the highest in group III (657g). Chickens of groups II and IV (with 0,3 and 0,9mg Se/kg of feed) realized breast mass of 627,90 and 633,12g. Compared to group I, average breast mass of chickens in groups III and IV was considerably higher (P < 0,05 and P < 0,01). Share of breast in the mass of processed carcass was the highest in groups III and IV (37,40 and 37,86%), and the lowest in group II (36,0%). In chickens of group I the stated value was 36,47%. Average share of thighs in the mass of processed carcass was approximately the same in all investigated groups. The highest value (14,4%) was established in chickens of group II, and the lowest (13,98%), in chickens of III investigation group. Chickens fed organic selenium in diet (0,3, 0,6 and 0,9mg/kg) had by 3,80, 3,74 and 3,18% higher share of drumsticks in the mass of processed carcass compared to group I. .

A 16-week experiment was conducted to compare effects of various levels of sodium selenite (SS) and Se-enriched yeast (SY), on the whole-egg Se content and hen's productivity. One hundred Shaver 579 hens, 27 weeks old, were placed on one of five experimental treatments. Each treatment was replicated four times with five hens per cage. Treatments consisted of feeding a low Se diet without supplementation (basal diet) or basal diet with one of two levels of supplemented Se (0.4 or 0.8 mg/kg) supplied by SS or SY. All supplemented treatments had significantly higher whole-egg Se concentration from basal diet (P < 0.05). On the same supplemented level, hens fed on SY had higher egg Se content from hens feed on SS (P < 0.001). No effects of dietary treatments on egg weight, percentages of dirty and cracked egg, and feed intake and conversion of feed were observed throughout the trial (P < 0.05). In the first 8 weeks, there was no significant difference (P < 0.05) in hen-day egg production among treatments. From the ninth week on to the end of the trial, supplementation of SY to hen's diet resulted in a higher egg production than SS (P < 0.01).

The objective of these investigations was to examine the influence of prebiotics based on mannan-oligosaccharides and polysaccharide complexes of micro elements (Fe, Cu, Zn, Mn) on production results and abattoir parameters for broilers of the hybrid Arbor Acres. The experiment was performed on 186 chicken divided into three equal groups, it lasted 42 days and was divided into 3 phases. The first phase lasted 21 days, the second 14, and the third seven days. The complete mix for initial fattening of broilers was used from days 1-21, and complete fodder mixes for closing fattening from days 21-35, and on days 35-42 of the experiment. Feeding was ad libitum and the broilers were maintained in a floor system. Broilers fed mixes of standard raw material composition and the usual nutritive values achieved an average daily growth of 49.10 g at an average daily feed consumption of 115.55 g and with food conversion of 2.35, while the yield was 71.90%. The addition of prebiotics based on mannan-oligosaccharides resulted in an increased average daily growth by 14.95% with a lower feed consumption by 2.67% and better conversion by 15.32%, while the yield was approximately the same as in the control group. The use of mixes to which polysaccharide complexes of micro elements have been added (Fe, Cu, Zn, Mn) resulted in a higher daily growth by 11.43%, with a lower feed consumption by 4.28% and better conversion by 14%. The yield was approximately the same in this group as in the controls. The results realized in these investigations, throughout the experimental period, indicate that the use of the examined additives significantly affected the growth and body mass of chicks and that it is nutritionally and economically justified.

The aim of this study was to investigate the influence of organic and inorganic Fe supplementation on productivity of broiler chickens. The trial was conducted on 200 Arbor Acres chickens divided into four equal groups. Birds from all groups were fed standard broiler feed, supplemented with 40 mg/kg of Fe originating from different sources: Group I (FeSO4), Group II (Fe bound to yeast), Group III (ferrous ascorbate) and Group IV (iron chelate). From each group, 10 birds were sacrificed on the 21st, 35th and 42nd day and the following parameters were measured: body mass, daily body mass gain, food consumption and conversion rate. At the end of the trial, the highest average body mass was measured in the group supplemented with ferrous ascorbate (15,51% higher when compared with the group supplemented with FeSO4). The conversion rate was lower in birds supplemented with organic iron forms and had the lowest value in the group supplemented with ferrous ascorbate.

The effect of high levels of inorganic selenium (NaiSeOs) was investigated on activity GSH-Px in blood plasma of chickens. For experiment, 140 chickens were used which were divided in 7 groups. The experiment lasted 42 days. The chickens of I group were not fed supplemental selenium. The chickens of II III, IV, V, VI and VII group were fed 2, 5, 10, 15, 20 and 30mg Se/kg of diet in form of Na2SO3. For determination of activity of GSH-Px spectrografic method was used. The highest activity of GSH-Px was found at the beginning of the experiment in all examined chickens (the eleventh day). The chickens of II, III, IV and V group had significantly higher activity and chickens of VI and VII group had lower activity then I group.

The goal of this research was to investigate the effect of various levels of organic selenium (selenized yeast) on the weight gain and feed utilization of chicken in fattening. The experiment was carried out on 120 chicken of line hybrid Hybro-PN, divided into four groups (treatments), lasting six weeks. All groups of chicken were fed complete mixtures, while selenium was added to feed in the form of selenized yeast, in quantities of 0 (Group I); 0.3 (II) 0.6 (III), or 0.9mg/kg (IV). Chicken were measured, and care was taken to keep groups uniform (Groups: I - 36.17g; II - 37.01g; III - 37.16g, and IV 36.59g). During the experiment, every seven days, body weight of all animals was measured, as well as feed consumption for each experimental group. At the end of fattening, the highest body weight was established for chicken in Group III (2647.50g), followed by chicken in Groups II and IV (2595.89 and 2526.55g). Mentioned values were statistically significant (PO.01) by chicken and groups (2309.lg). Average daily feed consumption during the whole fattening period was highest in Group III, and lowest in Group I. For the last week of fattening it amounted to 196.38g (Group III), i.e. 179.41g (Group I). However, for chicken in Groups II and IV, these values were somewhat lower, as compared to chicken in Group III (190.50 and 185.15g). Food consumption per 1 kg gain was lowest in groups fed rations with added organic selenium (Group II - 1.65; III and IV - 1.67). Chicken in group I had the worst feed conversion (1.73).

An experiment lasting 45 days was performed on 125 Hybro broilers divided into five groups. All compounds for broiler feed mixes used in the experiment contained 0.15 mg Se/kg, in the form of sodium selenite. The control group (K-group) of broilers was fed mixes without added organic selenium, and the experimental groups with mixes to which selenium, in the form of selenized-yeast, was added in quantities of 2, 5, 10, or 15 mg/kg. Selenized yeast (ICN - Gaienika) was obtained from beer yeast and contained 1.51, or 1.45 mg/g total, or organically bound selenium. At the beginning of the fattening period, GSH-Px plasma activity in broilers of the K-group ranged around 16.55 μkat/L, while GSH-Px plasma activity in broilers of experimental groups was statistically significantly higher, but without any major differences among the individual groups (on the average 25.53fjkat/L). In the blood plasma of K-group, GSH-Px activity dropped already in the second week of life and was maintained at a relatively constant level (about 10 μkat/L) until the end of the experiment. The same phenomenon was observed in the experimental groups, but the trend of declining GSH-Px activity in blood plasma was more expressed, and, contrary to the control group, was expressed also in the later phases of the experiment. In the 3rd week of the fattening period, GSH-Px plasma activity in broilers of the control and experimental groups was relatively equal, and then the plasma activity of GSH-Px in broilers of the experimental groups decreased, but there were no major differences among the individual groups.

The main objective of this study was to investigate the importance of the sires effect on fenotypic variability of production traits of performance tested boars of Large White, Landrace. and Hampshire breeds of pig. The data used in this study were collected from 738 performance tested young boars at the PKB Pig Testing Station in Padinska Skela, from 1995 to 2001. Analysed traits were initial age (IA), final age (FA), test duration (TD), average daily gain on test (ADG), lifetime ADG (LADG), amount of total consumed feed (TF), feed conversion ratio (FCR), daily feed intake (DPI) and body composition traits taken by ultrasonic equipment PIGLOG 105 (backfat thickness - BF1 and BF2, muscle depth - MD and lean meat content - LM) Data was analysed by fixed models of least squares method. Analysis of variance showed that sires nested within Hampshire breed highly significant influenced all investigated traits. Growth, feed efficiency and body composition traits except muscle depth, were highly significant influenced by sires of Large White breed. All feed efficiency traits and muscle depth were not influenced by sires within Swedish Landrace breed.

All mineral matter, essential or non-essential, can have a significant influence on production results and the health of animals, if large quantities of them are present in a feed ration. A maximally tolerant content depends on the animal specie and category. Many factors, such as physiological status (growth, lactation, etc.), nutritive status, content and ratio of nutritive matter in the ration, duration of exposure, and the biological level of utilization of elements, also affect the maximally tolerant content of mineral matter in feed. The content of certain mineral matter in plant feed significantly depends on the soil factor, as well as the content and level of utilization of mineral matter from the soil. Mn, Se and Mo can be present in plant feed in such quantities as to induce toxicosis. Industrial contaminants, Cd, Pb or F, can contaminate plants, in particular their leaves, in quantities which lead to the appearance of clinical signs of conventional toxicosis. Moreover, natural water can contain large quantities of S, F, Na, Mg, or Fe, and certain mineral matter can get into water through industrial waste. In addition to the above, it is possible to cause unwanted effects through the frequent, but primarily unprofessional use of mineral additives, since it is extremely important, besides meeting the mineral requirements of each individual element, to secure a ratio among the mineral matter themselves as well as with other nutritive matter. Mineral matter present in food are in mutual interference, and these relations can be synergistic or antagonistic. The sufficiency of a large number of mineral matter has a negative effect on the utilization of other matter (conditional and/or border deficiency), while certain elements cause the clinical appearance of toxic effects. The accidental intake of large quantities of certain mineral matter is revealed as clinical signs of acute toxicosis, which is very different from chronic effects caused by the intake of increased quantities of mineral matter over a longer time period.

The object of this research-developmental project is the production of quality pig halves. By the application of various methods of selection and breeding along with optimal conditions of nutrition, care and keeping carcass quality of breeding animals and fatteners shall be improved. Another aim of the project is the improvement of health state and performance of pigs by securing optimal microclimate factors, keeping conditions and housing system. The economical valorization of quality pig halves shall also be established. The research has been carried out in three breeding stocks (Breeding stock 1 - PKB "IMES" AD, Padinska Skela; Breeding stock 2 - DP "Stari Tamis", Pancevo; Breeding stock 3 - Institute for Animal Husbandry also one of parties who realize the project) who are all the users of the research results. In the second year of research we worked on the improvement of reproductive traits of breeding pigs as well as fattening and slaughter traits of three-race and four-race crossing breeds, optimal nutrition, possible use of probiotics in the nutrition of piglets and fatteners, preventing of digestive disorders by use of various probiotic populations, establishing microclimate factors and economical indicators in pig production. In the first two research years the results were published in leading scientific journals of national importance, and reported at the international and national scientific meetings. The study displays the published results of the project in question.

The objective of these investigations was to examine the influence of raw and thermally processed soybean kernels (ZP Lana and ZP Nena) on growth and feed utilization of broiler chicks. The experiment was conducted on 200 chickens (Arbor Acres) divided into four groups (treatments). The first group was fed a mix containing raw soybean kernels (ZP Lana) with a smaller quantity of trypsin inhibitors, and the third with raw kernels of a standard varietry (ZP Nena). The second and fourth groups were administered mixes containing raw kernels that were previously thermally processed. In the first period of the fattening process (days 1 -21), the amount of raw or thermally processed kernel was 20%, in the second period (days 22-35) 24%, and in the third period (days 36-42) 22 %. The experiment lasted 42 days. The chickens were maintained on the floor, feed was ad libitum, comprising complete mixes composed on the grounds of the recommendations for the given hybrid. The results obtained in the course of these investigations over the entire experimental period indicate that the use of thermally processed soybean kernels (groups two and four), in comparison with the use of raw kernels (groups one and three), significantly (P<0.01) affected growth and body mass of chickens. Furthermore, significantly bigger values (P<0.01) for the given parameters were determined also in chickens of group one in comparison with group three. Using thermally processed kernels (groups two and four) affected an increase in the daily consumption of feed not only in a certain period, but during the duration of the entire experiment(days 1-42). The listed treatments (groups two and four) in this period (days 1-42) also considerably increased feed conversion (1.83 and 1.85) in comparison with experimental groups one and three.