L. Peric

Application of alternative growth promoters in broiler production

Subsequent to banning of use of antibiotics as growth promoter sin poultry nutrition, numerous studies turned to finding of alternative solutions, i.e. other, natural substances, which would have positive effect on chicken growth and feed conversion. Today, several groups of these additives are in use, and most often probiotics, prebiotics, enzymes, acidifiers, antioxidants and phytogene additives. Considering that each of the stated groups has its own specificities, objective of this work was to present main mechanism of their action and to present their effect on production results in fattening of broiler chickens through review of research published in this field.

Beneficial effects of phytoadditives in broiler nutrition

During the past fifteen years, phytoadditives in animal nutrition have attracted attention for their potential role as alternatives to antibiotic growth promoters. The goal of this paper is to review the current scientific data on the use of phytoadditives in broiler nutrition. The efficacy of phytogenic applications in broiler nutrition depends on several factors, such as composition and feed inclusion level of phytogenic preparations, bird genetics, and overall diet composition. Difficulty arises when comparing different studies using phytoadditives due to the large variation in composition and sourcing, thus the potential biological effects of phytogenic compounds may differ. However, a great amount of research data supports a potential role of phytoadditives as natural, non-antibiotic growth promoters in broiler nutrition. The mechanisms behind growth promotion are far from being elucidated, as data on phytoadditive effects on nutrient digestibility, gut function and the immune system are still scarce. Phytogenic intake may certainly depress pathogen growth in the gut, however an understanding of their effects on the complex gut ecosystem is still far from clear. There is insufficient amount of studies describing the effects of phytoadditive dietary intake on carcass meat safety, whereas the beneficial effect of phytogenics on carcass meat quality is very well documented. As the last point of this review, further considerations on the efficient applications of phytoadditive compounds in broiler nutrition are given.

The effect of stocking density on certain broiler welfare parameters.

In broiler production, stocking density, i.e. floor surface per chicken, is very important welfare factor which directly and indirectly influences and determines the level of growth of chicken body weight, but it is also related to other welfare indicators. Objective of the paper was to define the broiler welfare in different stocking densities by evaluation of their walking ability (gait score), feathering, incidence and degree of hock burns, foot pad lesions, and by determination of the biochemical blood parameters (glucose concentration, total cholesterol concentration), as indicators of condition of stress. One day old chickens of Hubbard genotype were housed in boxes in floor rearing system, in 3 stocking densities and 5 repetitions of each treatment. Treatment A scored stocking density of 10 birds/m 2 ; treatment B, 13 birds/m 2 and treatment C, 16 birds/m 2 . Results of the trial indicate absence of significance of differences between trial groups of broilers in regard to their walking ability, condition of skin and legs, and stress indicators. In general, broiler welfare in all trial groups was satisfactory. However, determined tendencies of worsening of the condition of litter, increase of the frequency of lower scores for walking ability (gait score), hock burns and foot pad lesions which occur with increase of stocking density, indicate the importance of this rearing factor and need to define limiting stocking densities from the aspect of broiler welfare but also economical efficiency of production.

Improving the poultry sector in Serbia: major economic constraints and opportunities

Poultry production is an important livestock sector in Serbia. It accounts for about 12% of the total value of countrys livestock production. Providing relatively cheap food of high quality it is nowadays of particular importance due to economic transition problems and the consequent economic crisis that the country has faced since the beginning of the 1990s. However, despite the sectors importance, poultry production has actually had no institutional support for many years, and the poultry population, as well as broiler meat and table eggs production, has significantly declined over the last two decades. The sector is characterized by insufficient level of concentration, specialization, vertical integration and efficiency. It is estimated that small-scale farms and backyard poultry production in Serbia account for more than half of poultry meat production and two thirds of egg production, with a significant seasonal impact on local markets. The following paper gives an overview of both commercial and small-scale poultry production in Serbia and examine the major economic constrains to and opportunities for poultry sector improvement needed in view of Serbias prospective EU integration.

The effect of genotype of broiler chickens on carcass quality in extensive rearing system

Research was carried out on chickens of four genotypes: two slow-growing genotypes, Master Gris (MG) and Farm Q (FQ), one fastgrowing, Hubbard Classic (HC) and one medium-growing Red Bro (RB). To the age of 3 weeks, chickens were reared according to all technological norms for intensive production. After that period, chickens were moved and fattening in extensive conditions resumed, using unlimited free range. The significance of genotype on body mass was established. The greatest final body mass was established in chickens of the Master Gris genotype (1983 g) and the lowest in Farm Q (1371 g). Fast-growing chickens of genotype Hubbard Classic at the age of 84 days had body mass at the level of medium-growing Red Bro genotype at the age of 91 days (1730 g, and 1759 g, respectively). In accordance to the established body mass, slaughter yields of Farm Q broilers were significantly the lowest. Also, chickens of this genotype also had significantly (p<0.05) lower share of abdominal fat compared to other genotypes. Chickens of Master Gris and Red Bro genotypes had significantly greater shank length (22.57 and 21.01 g/mm, respectively), whereas in fast-growing genotype Hubbard Classic a significantly greater breast angle (90.15 degrees) was determined. Accordingly, share of breast (15.90 %), as well as share of breast meat (10.11 %) was significantly greater in carcasses of Hubbard Classic chickens.

Use extruded rapeseed meal in the feed of broiler chickens

The aim of the study was to investigate the effects of extruded rapeseed meal in the diet on broiler performance. Chickens of Ross 398 hybrid were used in the trial. The trial lasted 42 days. Rape seed meal was extruded prior to use and included in the diet at the level of 4% (group 2) and 8% (group 3), and control group of chickens (group 1) fed the standard mixture based on corn, soybean meal and soybean grits. Chickens of the control group scored the highest ranking and realized the final body mass of 2212 g, whereas the chickens of group 2 had the final body mass of 2191 g, and chickens of group 3 with final body mass of 2148 g were the worst. Falling behind of the trial groups in relation to the control group in regard to the body mass at the end of the trial was by 0,91% group 2 and by 2,89% for group 3. Feed conversion ratio was the best in group 2, followed by control group, and the worst was the group 3 (1,882; 1,866; 1,894, respectively). The lowest mortality rate was realized by chickens of the control group, followed by group 2 and group 3 (4,00%; 4,33%; 5,33%, respectively). The control group of chickens had the best production index value, followed by group 2 and the lowest value of the production index was established for chickens of group 3 (270,95; 265,18; 255,63, respectively). It can be observed that the depression in trial groups was within the limits of toleration, which indicates that extruded rapeseed meal can be included in the diets for fattening chickens in ratio up to 10%.

Effect of different litter treatments on production performance of broiler chickens.

In modern poultry production, foot pad dermatitis (FPD) represents one of the main problems on broiler chicken legs with significant affect on animal welfare and performance. This problem is not solved by the using of straw as litter. Different treatments of straw are needed to eliminate the adverse effects of this material as litter. The most widely used method to improve the quality of litter is chopping straw and application of microbial products on that. These procedures can decrease the moisture in the litter and reduce the population of microorganisms whose activity produces ammonia, and hence improving environmental conditions in facilities. The experiment involved four treatments with four replications with a total of 300 broilers per treatment. The treatment I was unchopped straw, treatment II was chopped straw, treatment III unchopped straw with the addition of microbial products, and treatment IV was chopped straw with the addition of microbial preparation. Duration of trial was 42 days. During the experiment, the following production parameters were measured: body weight per week of the experiment, feed conversion ratio, mortality and FPD. Results of the trial point out that the best production results were in treatment IV with an average final body weight of 2.456g and feed conversion ratio of 1.71. [Projekat Ministarstva nauke Republike Srbije, br. TR 31033]

Effects of supplementation with α-tocopherol, ascorbic acid, selenium, or their combination in linseed oil-enriched diets on the oxidative status in broilers

&NA; A trial was conducted to investigate whether, and if so to what extent, the combined supplementation of vitamin E, vitamin C, and selenium was superior to their sole supplementation concerning the oxidative stress induced by a high n‐3 dietary polyunsaturated fatty acids (PUFA) intake in broilers. Four hundred 21‐day‐old Ross 308 male broilers were allocated to 5 experimental groups fed the following linseed oil (5%)‐enriched finisher diets: Cont (no supplement), +E (200 IU vitamin E/kg feed), +C (250 mg vitamin C/kg feed), +Se (0.2 mg selenium/kg feed), or +ECSe (concentrations as in the sole supplementation, combined). Analyses of malondialdehyde (MDA), vitamin C, and &agr;‐ and &ggr;‐tocopherols in plasma, antioxidant capacity of water‐ (ACW) and lipid‐ (ACL) soluble compounds in serum, and glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities in whole blood were performed. In breast muscle, analyses of MDA, &agr;‐ and &ggr;‐tocopherols, ACW, selenium, and fatty acid (FA) composition were carried out. Birds fed the combination of antioxidants showed reduced average daily gain (ADG) and average daily feed intake (ADFI) and, as +E, lower MDA and &ggr;‐tocopherol, together with raised &agr;‐ tocopherol levels in plasma and lower MDA and raised &agr;‐ tocopherol levels in breast muscle compared to the control. The combination of antioxidants in the +ECSe group raised GPx activity in whole blood compared to the control. In conclusion, results indicated that vitamin E is the most effective antioxidant to alleviate oxidative stress caused by high dietary PUFA and that the supplementation with additional vitamin C and selenium did not have clear synergistic effect.

Effect of Production Systems on Quality and Chemical Composition of Table Eggs

Summary Production system is one of the most important factors which have an effect on egg quality. In recent years consumers have paid more attention to the housing system in which eggs are produced with a significant increase of their interest in organic and functional food. Some consumers perceive omega-3 enriched eggs and free range eggs as beneficial for their health. Therefore, the aim of this work was to determine the chemical composition and the internal and external quality of eggs produced in conventional cages, free range systems and of omega-3 enriched eggs. Samples of 30 eggs from three different production systems were taken from the market. For eggs from each system the internal and external egg quality traits were examined as well as the protein and fat content. The results showed lower fat content in eggs from cages (P<0.05). Free range and omega-3 eggs had higher content of protein in egg white compared to the conventional ones (P<0.05). Production system significantly influenced the shell breaking strength, Haugh units and yolk color. The shell breaking force was significantly higher in free range eggs (P<0.05). The highest value of Haugh units was found in free range eggs and the lowest in omega-3 enriched eggs. The results of this work confirmed that there are differences in quality and the chemical composition of eggs from different production systems.

Determining Some Exterior and Interior Quality Traits of Japanese Quail Eggs (Coturnix japonica)

The aim of this research was to determine some exterior and interior quality traits of Japanese quail eggs. A total of 60 Japanese quail eggs were collected from two different farms near Novi Sad, and the eggs quality traits were tested in the laboratory of poultry science at the Department of Animal Science of the Faculty of Agriculture in Novi Sad. The egg weight, albumen weight, yolk weight, shell weight, shell breaking force, shell thickness, albumen height and egg yolk colour were determined. The external and internal egg quality traits of quail eggs from two farms in Serbia do not differ from the results of quality traits from other countries.