Sreten Mitrovic

The effect of mineral adsorbents in poultry production

The quality of poultry feed is an important precondition to achieve optimal production results, and the preservation of the health status of animals, especially in intensive livestock production, hence it is necessary to control both raw materials and finished feed mixtures. The presence of fungi (moulds) in food for animals is a natural phenomenon, not an exception. Sources of contamination of poultry feed with fungi and resulting mycotoxins vary, starting with raw materials (e.g. corn as the most common component) during harvest and transport, during storage of raw materials and finished products, as well as in the production process and manipulation of poultry feed. Mineral adsorbents are increasingly used in poultry production, especially in the nutrition of various types and categories of poultry, to control fungal contamination. Using different mineral adsorbents in poultry nutrition can prevent the losses due to mycotoxicosis. It can also prevent appearance of toxic residues in poultry products, improve production and reproductive ability of birds, and contribute to improving the quality of poultry products. In addition, the use of mineral adsorbents in poultry feeds has application in neutralising the harmful effects of mycotoxins in buildings where poultry is reared.

CARCASS COMPOSITION AND CHEMICAL CHARACTERISTICS OF MEAT FROM BROILER CHICKENS REARED UNDER INTENSIVE AND SEMI- INTENSIVE SYSTEMS

Poultry rearing systems have captured the attention of scientists for many years. A number of attempts have been made to introduce new technologies in rearing poultry for meat and egg production aiming at improving rearing conditions, protecting the environment and enhancing the quality of poultry products. Given the above, the objective of this study was to present the results of an evaluation of the effect of rearing system on major meat quality traits (percent yield of primal cuts in cold carcasses, tissue percentage in major primal cuts and chemical composition of muscle tissue). The experiment involved a total of 400 Hybro broilers reared under two different systems (intensive and semi-intensive systems). The fattening period and slaughter and dressing procedures were followed by measurement and meat sampling for chemical analysis. The results obtained show that broilers reared under the semi-intensive system had a somewhat higher percentage of drumsticks and breasts i.e. first class meat, as well as a higher percentage of breast and thigh muscles. Moreover, the protein content of breast, thigh and drumstick muscles was higher in broilers reared under semi-intensive conditions. As for the fat content of primal cuts, it was found to exhibit higher values in broilers reared under the intensive system. Overall, the results suggest better performance for most traits in free range broilers reared under semi-intensive conditions as compared to those reared intensively.

Carcass characteristics of two strains of native broilers (White Naked Neck and Black Svrljig) fattened under a semi-intensive system

This study involves the analysis of two breeds [Naked Neck (NN) and Svrljig chickens (Sv)], that is, strains [White Naked Neck (WNN) and Black Svrljig strain (BSv)] of chickens (birds) of both sexes reared under a semi-intensive system until day 84 of age. At 28 days of age, the test birds were kept in a litter housing system (about 8 birds/m 2 ), following which they were provided a free-range paddock at 4 m 2 /bird. The following parameters were evaluated in the two strains and sexes of broilers (totalling 56 chickens) aged 84 days: body weight at slaughter, carcass weight, yields of breasts, thighs, drumsticks, wings, pelvis, back, head, neck, feet, abdominal fat and giblets. At the end of the fattening period, the test broilers of both sexes of the WNN strain had higher values (P 0.05); however, a similar yield was obtained for ready to grill carcass (61.73 to 61.99%) when compared with the black Svrljig strain. The differences obtained were not statistically significant (P>0.05). In addition to the genotype (breed, strain), broiler sex had a statistically significant effect (P<0.001; P<0.01; P<0.05) on body weight, carcass yield, yields of drumsticks and thighs, wings, head, feet, giblets and abdominal fat. Specifically, male broilers were found to have higher live body weight (1669.29 to 1480.07 g), carcass weight (1342.86 to 1198.28 g), yields of head (5.13 to 4.39%), drumsticks and thighs (34.26 to 33.96%), feet (5.39 to 5.06%) and giblets (6.46 to 6.31%), whereas the relative yields of carcass (conventional processing (CP): 80.96 to 80.44%; ready to roast (RR): 73.02 to 72.19%; ready to grill (RG): 62.30 to 61.45%), wings (14.06 to 13.76%) and abdominal fat (1.13 to 1.07%) were higher in female broilers.

Broiler meat quality: The effect of rearing system and length of fattening period

Broiler meat production in recent years has been oriented towards the implementation of non-commercial rearing systems aimed at improving broiler rearing conditions, enhancing meat quality and improving the environment. This study presents productive and slaughter results of broilers reared under two non-commercial systems, including extensive indoor and free-range systems. Length of fattening period was 63 days. On days 49 and 63 of the experiment, male and female broilers were randomly selected from both rearing systems and slaughtered thereafter to be evaluated and compared for the following traits: dressing percentage and percentage yield of primal carcass cuts, as dependent upon rearing system, length of fattening period and broiler sex. The results showed a higher dressing percentage in broilers slaughtered on day 49, regardless of the higher carcass weight of broilers slaughtered on day 63. Broiler sex had a highly significant effect on the percentage yield of breast, thigh and drumstick in the dressed carcass (P<0.01), whereas the percentage yield of thighs was also statistically highly significantly affected by rearing system (P<0.01). Rearing system, length of fattening period and the interaction of these factors had no significant effect (P>0.05) on the percentage yield of primal cuts (breast, thigh, drumstick, wing, back and pelvis), excepting that of pelvis which was significantly affected by rearing system (P<0.05).

The influence of age on the exploitation period in broiler reproduction of parents in Ross hybrid 308

These investigations were intended to identify the influence of parental flock age at heavy hybrid Ross 308 (usage period) on more important reproductive capabilities (carrying eggs intensity of brood eggs, egg mass, one day old chick mass, relative chick mass share in complete egg mass) and consumption of food per processed – hatched chicken (final product of production cycle). Flock usage period lasted for 40 weeks (all eggs), respectively, 38 (brood eggs) weeks and there was possibility, based on achieved results, with evaluation of phenotype correlation, to get some concrete conclusions about the age influence on analyzed parameters during mentioned flock rising period. Phenotype correlation among investigated characteristics has been identified since second half of parental flock using period, since 41st week age (20th carrying eggs week) up to the end of production process when parental flock was 61 week old (41st egg production week). Flock age has statistically important positive (P < 0.05) influence on carrying eggs intensity of brood eggs until 49st week (rp = 0.391) and on percentage of chicken feasibility regard the complete number of inputted eggs until 50th week (rp = 0.434). There was statistically significantly increasing of egg mass and one-day old incubated chicken mass (P < 0.001) as parental flock was older. Complete correlation connectivity has been identified between egg mass and absolute chick mass (P < 0.001), while very strong (P < 0.001) or strong (P < 0.01) correlative connectivity between egg mass and relative chick share [(chicken mass/egg mass) x 100]. Further more, we determined negative correlation between eggs age and food consumption per hatched chicken for all time of breeding broiler parents, except 61st week when we determined positive coefficient of phenotype correlation (rp = 0.062), but statistically inconsequent.

Rooster body weight influence on the reproductive performance of the broiler parents.

In this research influence of the rooster body weight on reproductive performance of broiler parents was examined for Ross 308 and Cobb 500 hybrids. At the beginning of the productive cycle (24 weeks of age) for roosters Ross 308 hybrids average body weight of 3,030.00 g has been determined, while for Cobb 500 rooster average body weight was 3,045.00 g. In the 42 nd week of age (middle of productive cycle), body weight of Ross 308 roosters was 4,306.00 g and 4,323.00 g for Cobb 500 roosters, while at the end of productive cycle in the 61 st week of age Ross 308 hybrids had average 4.908,00 g and Cobb 500 had 4,918.50 g. Determined differences in body weight of roosters (15.00 g, 17.00 g and 10.50 g) in specific periods of productive cycle, as well as difference in body weight for the entire productive cycle (19.97 g) were not statistically significant (P>0.05). Between rooster body weight and fertilized eggs laying intensity positive statistically significant (P<0.001; P<0.01; P<0.05) correlation coefficients were determined. Between rooster body weight and hatchability percentage of the chicks positive statistically significant (P<0.001; P<0.01; P<0.05) correlation coefficients were determined for both hybrids. However, based on correlation coefficient it has been determined that rooster body weight had positive influence on laying intensity of fertilized eggs till 58 th week of age (Ross 308) and 60 th week of age (Cobb 500), while on hatchability of chicks it had positive influence till 58 th week of age for both hybrids.

Uticaj starosti nosilja lakog linijskog hibrida kokoši na osobine kvaliteta jaja

U cilju utvrđivanja osobina kvaliteta konzumnih jaja lakog linijskog hibrida Lohmann Brown sprovedena su istraživanja na živinarskoj farmi privatnog gazdinstva «Rakic komerc» doo, Batkovic, Bijeljina, Republika Srpska (BiH). U toku produkcije jaja posebna pažnja je obracena na cetiri glavne proizvodne faze, i to: 20. nedelja – SN20 (pocetak nosivosti), 28. nedelja - SN28 („pik“ maksimum), 48. nedelja – SN48 (sredina) i 72. nedelja starosti nosilja – SN72 (kraj proizvodnog ciklusa). U navedenim periodima, metodom slucajnog uzorka uzet je odgovarajuci broj nosilja, odnosno jaja za istraživanja, analizu i statisticku obradu utvrđenih podataka za ispitivane parametre. Pored mase, utvrđene su pojedine osobine kvaliteta jaja: masa jaja (g), dužina jajeta (mm), sirina jajeta (mm), indeks oblika jajeta (%), boja ljuske (poen), cistoca ljuske (poen) i boja žumanca (1-15 Roshe, pri starosnom dobu nosilja (SN20-72). Rezultati istraživanja pokazuju da razlike u prosjecnoj masi jaja porijeklom od razlicite starosti nosilja su bile statisticki signifikantne (P < 0,001). Analizirano komercijalno jato nosilja u proizvodnji konzumnih jaja, posmatrano u cjelini, ostvarilo je zadovoljavajuce rezultate kada su u pitanju parametri kvaliteta.

Effect of body weight of laying hens on production traits of broiler parents

Certain investigations have been conducted in two broiler breeder flocks of Ross 308 and Cobb 500 hybrids. At the beginning of the production cycle (24 weeks of age), an average laying hens’ body weight of 2680.40 g was found in the case of Ross 308 hybrid, and 2697.80 g in the case of Cobb 500 hybrid. During 42nd week of age (the middle of the production cycle), the body weight of laying hens was 3565.10 g (Ross 308) and 3599.05 g (Cobb 500), while at the end of the production cycle (61 weeks of age) the body weight of laying hens of Ross 308 hybrid was 3841.50 g, and 3850.00 g of Cobb 500. Identified differences in body weight of laying hens (17.40 g, 33.95 g, 8.50 g) in certain periods of the production cycle, as well as the difference in body weight of laying hens for the entire production cycle (23.26 g) were not statistically significant (P>0.05). More specific observation of the effect of body weight of laying hens on productive capacity of broiler breeders was determined by calculating the coefficients of phenotype correlation between the indicators studied. Thus, statistically significant (P<0.001, P<0.01, P<0.05) coefficients of phenotype correlation between the body weight of laying hens and the majority of production indicators have been determined, while statistically significant (P<0.001, P<0.01, P<0.05) correlation coefficients between the body weight of laying hens and the intensity of laying capacity for hatching and fertilized eggs have been determined, but for a shorter period of the production cycle.

Phenotype variability and relations between basic parameters of morphological development in young Balkan donkeys.

Balkan donkey is native breed of donkeys evolutively adapted to modest breeding conditions and different climatic systems including harsh and severe climate of Serbian mountains. Unfortunately, the purposes for breeding small donkeys have been lost during the 20th century so the population is regressing. There has been no selective breeding of the autochthonous donkeys in Serbia therefore the data on breed characteristics are recent and few. The monitoring of morphological characteristics of autochthonous Balkan donkey population in Serbia have been performed in aim to characterize the population and to define the importance of autochthonous donkeys as national genetic resource . The morphometric parameters evaluated i.e. height at withers (HWi) body length (BLe), thorax girth (TGi), cannon perimeter (CPe) and body weight (BW) in young Balkan donkeys bred in traditional conditions were used for establishment of the following body indexes: Index of Body Frame (IBF), Index of Body Compactness (BCI), Index of Conformation (CoI) and Dactyl-costal Index (DCI) reflecting body development and conformational relations in Balkan donkey population in Serbia.

The effect of triticales on the yield and meat quality of broilers.

The influence of triticale as feed on the production and carcass traits of chickens is investigated in this paper. The study was conducted on 200 chickens for fattening, hybrid Ross 308. In the experiment, two groups, or treatments, were formed, with 100 chickens in each group. One group was the control group K, with the classical mixture fed to broilers, and the other one was the experimental O-group of chickens fed diets containing triticale genotypes Kg 20. The first diet was the standard starter, grower I, grower II and finisher and served as control. The other rations contained 7.5%, 12%, 15% and 18% triticale as graded replacement for wheat. During the fattening period, health conditions of broilers were periodically monitored, and the following fattening traits as well: weight gain (individual measurements of all the chickens once a week), feed intake and mortality. The feeding trial lasted for 42 days. Feed and water supply for chickens was ad libitum applying floor housing system. Since the yield of carcass as well as the yield and share of some meat categories of cold carcass dressing are very important factors of quality, the influence of feeding treatments on some mentioned traits was monitored. The results showed that the chickens in the control group (K), which were fed a mixture of standard feed, had slightly better productive results compared to chickens in the experimental groups (O), which were fed diets containing triticale. The average body weight of broiler chickens at 42 days of fattening was higher in chickens of K-group - 1896.875 g, and slightly lower in broiler chickens fed triticale - 1846.684 g. By the end of the experimental period (42 days) the highest feed consumption per chicken was recorded in the control group of chickens (4.332 kg). The experimental group of chickens which were fed classical diets had lower mortality throughout the experimental period.