Forming egg shape index as influenced by ambient temperatures and age of hens

Abstract

The effects of ambient temperatures and hen?s age were investigated on poultry farm on the south of R. Macedonia, where annually average temperature was higher then other regions. In nine-month period of testing were included summer, autumn and winter season. Two groups of hens (ISA-BROWN) were used; the first one was younger (to 45-week age) and second was older (above 45-weeks). Once a month, about 100 eggs were examined, so the final number of tested eggs was 877. Average shape index was 75.19% for all eggs. High significance (p<0.01) showed both factors: age and season. Eggs from younger hens had index value of 76.16%, which is pointed on eggs with rounded shape, while older hen's eggs had index 74.20% with elongated shape. In summer and autumn season, most of eggs were with elongated shape while rounded shape had eggs in winter season.Uticaj faktora sezone i uzrasti kokosi ispitivan je u periodu od devet meseci, a bile su obuhvacene letnja, zimska i prolecna sezona. Kao materijal koriscena su jaja hibridne linije Isa-braon, a jaja su skupljana kod dve uzrasne grupe: jedna do 45 nedelja, a druga iznad 45 nedelja starosti. Jedanput mesecno ispitivano je oko 100 jaja od dve uzrasne grupe, tako sto je ukupan broj ispitanog materijala bio 877 jaja. Zivinarska farma od koje je uziman materijal smestena je na jugu R. Makedonije gde su prosecne godisnje temperature uvek vece od onih u ostalim regionima drzave. Analiza uticaja faktora sezone i uzrasti obavljena je metodom najmanjih kvadrata (Harvey,1990). Dobijeni prosek merenja indeksa svih jaja iznosio je 75,19%. Visoku signifikantnost (p<0.01) pokazao je faktor uzrast, tako su jaja mladih kokosaka imala vrednost indeksa od 76,17% sto je ukazivalo na jaja sa ovalnijim oblikom, dok su jaja starijih kokosaka imala indeks 74,20% i bila su izduzenijeg oblika. I uticaj sezone bio je visoko znacajan (p<0.01) na indeks kokosijeg jajeta. U letnjoj i jesenjoj sezoni vrednost indeksa bile su 74,88% i 74,83% i jaja su bila izduzenijeg oblika, dok se u zimskom periodu dobijala jaja sa prosekom od 75.85% i vecinom su imala okrugliji (ovalniji) oblik.