The effect of phase nutrition during starter period on production performances and nitrogen content in feces of broilers of different genotypes

Abstract

Objective of the research was to investigate the effect of phase nutrition, i.e. different mixtures used in broiler nutrition with phase reduction of protein cotnent during starter period on production peformances of fattening chickens of different genotypes and on nitrogen content in faeces. Differences between groups (treatments) were in the type of mixtures use din starter period, and according to the following program: T1 (control group) - nutrition consisted of mixtures with 23% of proteins in duration from day 1 to 21; T2 - from day 1 to 14, mixture containing 23% of protein was used, and from day 14 to 21, mixture with 20% of proteins; T3 - from day 1 to 7, mixture was used containing 23% of protein and from day 7 to 21, mixture with 20% of proteins; T4 - nutrition with mixture containing 20% of proteins in duration from day 1 to 21. During the trial period (from day 1 to 21) production parameters were followed. Nitrogen content was determined in a collective faeces sample. Results showed that chickens of different genotypes expressed different sensitivity to protein restriction. Comparing the trial groups with the control in the third week, in chickens of Ross 308 provenience significantly lower body weight was registered only in chickens of T4 group with the highest protein reduction. In Cobb 500 chickens, significantly lower body weight was determined in T3 and T4 trial groups. In case of both hybrids, in T2 group, slightly lower body weight was established, but without statistically significant difference compared to the control. Feed conversion in both genotypes was the highest in T3 and T4 treatments. The program of phase nutrition resulted in decrease of the nitrogen content in faeces. Based on obtained data it can be concluded that applied nutrition treatments with drastic protein reduction during starter period in both genotypes had negative effect on production performances. Therefore, the composition and dynamics of mixture changes must be taken into consideration when formulating the program of phase nutrition, in order to achieve both goals - decrease of protein content in feed with simultaneous diminished nitrogen excretion and achieving good results.

Cilj istraživanja je da se ispita uticaj fazne ishrane, odnosno različitih smeša za ishranu brojlera u kojima je sadržaj proteina smanjen fazno u starter periodu na proizvodne osobine tovnih pilića različitog genotipa i sadržaj azota u fecesu. Razlika između grupa (tretmana) bila je u tipu smeša u starter periodu, a prema sledećem programu: T1 (kontrolna grupa) - ishrana smešom sa 23% proteina u trajanju od 1. do 21. dana; T2 - ishrana od 1. do 14. dana smešom sa 23% proteina i od 14. do 21. dana sa 20% proteina; T3 - ishrana od 1. do 7. dana smešom sa 23% proteina i od 7. do 21. dana sa 20% proteina; T4 - ishrana smešom sa 20% proteina u trajanju od 1. do 21. dana. U oglednom periodu (od 1. do 21. dana) praćeni su proizvodni parametri. Sadržaj azota u fecesu određen je na zbirnom uzorku. Rezultati su pokazali da su pilići različitih genotipova ispoljili različitu osetljivost na restrikciju proteina. Poređenjem oglednih grupa sa kontrolnom u trećoj nedelji, kod pilića provenijence Ross 308 konstatovano je da je signifikantno manju telesnu masu ostvarila samo T4 grupa sa najstrožijom redukcijom proteina. Kod provenijence Cobb 500 signifikantno manja telesna masa utvrđena je za T3 i T4 oglednu grupu. Kod oba hibrida za T2 oglednu grupu utvrđena je nešto manja telesna masa, ali bez statistički značajne razlike u poređenju sa kontrolnom. Konverziju hrane kod oba genotipa imala je najveće vrednosti za T4 i T3 tretman. Programi fazne ishrane rezultirali su smanjenjem sadržaja azota u fecesu. Na osnovu dobijenih rezultata može se zaključiti da su primenjeni tretmani ishrane sa drastičnom restrikcijom proteina u starter periodu kod oba genotipa imali negativan uticaj na proizvodne performanse. Zbog toga se prilikom formulisanja programa fazne ishrane strogo mora voditi računa o sastavu i dinamici promene smeša, a kako bi se postigla oba cilja - smanjenje sadržaja proteina u hrani uz smanjenu ekskreciju azota i postizanje dobrih proizvodnih rezultata.