M. Lukic

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.

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.

Stocking density - factor of production performance, quality and broiler welfare.

Significance of stocking density in broiler production i.e. production performance, vitality and health condition of chickens, was established at the beginning of development of industrial poultry production. However, considering intensive development of selection work and creation of more productive genotypes which, at the same time, were more demanding in regard to rearing conditions, the current importance of this research is not diminished. In favour of this statement is also the complexity of the effect of stocking density which is direct, indirect, and interacted with other factors of rearing, which eventually reflects on all aspects of broiler production: economical efficiency, quality of products and broiler welfare aspects. In the paper a review of research results is presented with general objective to define optimal stocking density in broiler production based on comparison of effects on production performances, parameters of carcass quality and indicators of broiler welfare.

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.

The effect of genotype on production and slaughter properties of broiler chickens.

Objective of the research was to investigate the effect of genotype on production and slaughter properties of broiler chickens. The usual technology of broiler production was implemented, therefore fattening lasted 42 days. Trial included total of 2070 broiler chickens of following hybrids: Cobb 500, Ross 308 and Hubbard Classic. Chickens of genotypes Cobb 500 and Ross 308 realized significantly higher average body masses compared to Hubbard chickens. The highest mortality rate in the trial was recorded in Hubbard genotype. Chickens Cobb 500 and Ross 308 had the same feed conversion and statistically insignificant differences in production indices, whereas the values of these parameters in Hubbard chickens were significantly less favourable. The breast depth as carcass conformation measure showed no statistically significant differences between genotypes. Significantly higher values of breast angle were established in chickens of Cobb 500 compared to other two genotypes, whereas the highest values of thigh girth and the metatarsus length were established in Ross 308 chickens. Better slaughter results were obtained in carcasses of Cobb 500 genotype, chickens of both genders. Share of abdominal fat in percentage was similar in all genotypes, so the genotype had no significant effect on variation of this trait.

THE EFFECT OF STOCKING DENSITY ON INDIVIDUAL BROILER WELFARE PARAMETERS 2. DIFFERENT BROILER STOCKING DENSITIES

Stocking density is considered one of the most important factors for the welfare of broilers. This paper is continuation of the study in order to obtain full evaluation of the impact of different broiler stocking densities on production performance, condition of the broiler legs and body feathering, as welfare indicators but also indicators of the productivity and quality of produced chickens. The effect of three stocking densities (20, 15 and 10 birds/m2) was investigated in 4 repetitions on broilers of genotype Hubbard at the age of 3 and 6 weeks. At the age of 6 weeks stocking density of 20 birds/m2 resulted in significantly lower growth of broilers, higher mortality and higher incidence of leg lesions and problems with body feathering, compared to stocking densities of 15 and 10 birds/m2.

The effect of housing density on certain slaughter traits of broilers of Cobb genotype

Production of poultry meat organized on industrial principles, i.e. in intensive way, is characterized by housing of broilers in closed buildings, often in very high housing densities with completely controlled conditions of environment and nutrition. Objective of the research was to investigate the possibility for improvement of certain slaughter traits of broiler chickens using lower housing density of 12 birds/m2 of box floor area in comparison to control group which was housed in density of 16 birds/m2. Body masses of broilers of both sexes prior to slaughtering were higher in trial group (p 0,05) in trial group compared to control. On carcasses of investigated males in lower housing density the share of breasts was increased the most, and on female carcasses the share of drumsticks.

Incidence of footpad dermatitis and hock burns in broilers as affected by genotype, lighting program and litter type.

Abstract The aim of this study was to define the conditions for improving broiler leg health, thus ultimately promoting broiler welfare and greater economic efficiency of production, by investigating the effects of litter type, lighting program, or genetic predisposition on the incidence and severity of footpad dermatitis and hock burns. The study was conducted on broiler genotypes (G) Hubbard Classic and Ross 308. Litter (L) was either chopped straw or wood shavings. Lighting programs (LP) were applied when broilers were eight days old. One lighting program (LP1) was designed so that chicks between 8 to 39 days of age were exposed to 16L:4D:2L:2D, and received 23L:1D between 40 to 42 days of age. The other lighting program (LP2) was a gradual extension of photoperiod after restrictions in the second week: 16L:8D (8-14 days), 16L:3D:2L:3D (15-21 days), 16L:2D:4L:2D (22-28 days), 16L:1D:6L:1D (29-35 days) and 23L:1D (36-42 days). Evaluations of footpad lesions and hock burn, according to the method described by Thomas et al. (2004), were carried out individually for each bird, on days 21 and 42. Based on the average score and the frequency of the worst forms of footpad dermatitis, better growing conditions for broilers were found when wood shavings were used as litter material rather than the chopped straw (P<0.01), and when a lighting program with gradual lengthening of photoperiod and with intermittent light/ dark periods (LP2) was applied, compared to a moderate-constant photoperiod lighting program (LP1) (P<0.01). The Ross 308 broiler genotype, despite its lower body weight, showed a greater tendency to develop footpad dermatitis and hock burns. Hock burns developed more slowly than footpad dermatitis, and thereby, would be likely to exhibit a smaller adverse effect on broiler welfare and quality of chicken feet.

Fungal contamination and natural occurrence of ochratoxin A (OTA) in poultry feed.

Total fungal count, the presence of potentially toxigenic fungi and natural occurrence of ochratoxin A (OTA) were studied in 30 poultry feed samples (14 samples of feed for chickens and 16 samples of feed for laying hens), which were collected from different farms in Serbia at the beginning of year 2014. The total number of fungi was determined by the method of dilution and OTA was detected using the imunoadsorption enzymatic assay (ELISA). In most of the samples of chickens feed (50%) the total number of fungi was 1 - 3 x 102 CFU g-1, and in feed for laying hens the highest number of samples (37.50%) had the total fungal count from 1.4 to 4.8 x 104 CFU g -1. The species of genera Aspergillus and Penicillium were identified as producers of OTA in 21.43% and 42.86% of chickens feed samples and in 68.75% and 25% of samples of feed for laying hens. The presence of OTA was detected in 100% of samples of feed for chickens and laying hens, with average concentrations of 34.40 μg kg-1 (feed for chickens) and 43.89 μg kg-1 (feed for laying hens). The total fungal count and content of OTA were not above the maximum allowed quantities, even though the presence of Aspergillus and Penicillium species was found in a large number of samples (up to 68.75%). These results indicate that the tested samples of poultry feed were mycologically and mycotoxicologically correct. [Projekat Ministarstva nauke Republike Srbije, br. TR-31023 i br. TR-31033]

Effects of intensity of light and stocking density on broiler body weight and yield of valuable carcass parts

In order to determine the effect of intensity of light and stocking density, as well as the interaction of light intensity x stocking density on body weight and individual carcass traits, an experiment was performed on 1200 broilers of the Ross 308 genotype. The investigated factors were the intensity of light (LI): 20 lx (K) ; 150 lx (O) and stocking density (SD): 10 broilers/m (A); 13 broilers/m (B); 15 broilers/m (C), in 4 repetitions. The light source was incandescent bulbs of adequate intensity and a light program 16L: 4D: 2L: 2D was applied. Broiler body weight was controlled on 11th, 21st, 35th and 42nd day, by individual measurement of all chickens in the trial. The average sample containing 12 chickens per treatment with equal gender representation (total of 72 broilers) was used to study the slaughter quality of carcasses based on the parameters of absolute and relative yield of more valuable carcass parts (breast, thighs and drumsticks) and meat in the more valuable parts of the carcass. The effect of light with different intensity on the body weight differed depending on the broiler rearing phase. The interaction effect of the intensity of light and stocking density on the body weight of broilers was confirmed in all stages of growing up to the age of 42 days. A higher intensity of light (150 lx) showed the potential to alleviate the negative effects of higher stocking density (15 broilers/m) on the final body weight of the broiler. The carcass traits were not significantly affected by the intensity of the light, while the stocking density, as well as the intensity of the light x stocking density did influence the yield of whole breast and the yield of breast meat.