Regression analyses in turkey growth description

Abstract

Istraživanje je provedeno na 30 muških i 30 ženskih pura podrijetlom Nicholas 700. Pure su tovljene tijekom 19 tjedana. U cilju opisivanja rasta pura koristile su se stope rasta, asimetrična S-funkcija, eksponencijalna, razlomljena i jednostavna linearana regresijska analiza. Procjena točke infleksije i odvajanje faze rasta dobivena je pomoću asimetrične S-funkcije (Kralik i Scitovski, 1993). Purani su na kraju tova bili teži od pura za 34,63%. Razlike na kraju, ali i tijekom cijelog trajanja tova bile su statistički značajne (P<0,001). Prema asimetričnoj S-funkciji faza progresivnog rasta kod pura započinje nakon 5. tjedna života, dok kod ženki započinje par dana kasnije. Biološki maksimum kod mužjaka bio je 17,966 kg, dok je kod ženki 12,889 kg. Intenzivni rast kod ženki završava početkom 15. tjedna života, a kod mužjaka nekoliko dana kasnije (na kraju 15.tjedna starosti). Točka infleksije kod purana je sredinom, a kod pura na početku 10. tjedna života. Asimetrična S-funkcija najbolje je prilagođena opisivanju rasta pura od istraženih regresijskih modela.Study was conducted on 30 male and 30 female turkeys, Nicholas 700 provenience. Turkeys were fattened during 19 weeks. Growth rate, asymmetric S – function, exponential function, rational function and simple linear regression analysis were used to describe turkey growth. Inflection point and growth phase separation estimate were obtained by asymmetric S-function (Kralik and Scitovski, 1993). At the end of fattening, male turkeys had more weight than females by 34,63%. Differences in weight between male and female turkeys at the end, as well as during fattening were statistically significant (P<0,001). According to asymmetric S-function, the phase of progressive growth in male turkeys begins after the 5th week of life, and in females it begins a few days later. Biological maximum in male turkeys was 17,966 kg, while in females it was 12,889 kg. Intensive growth in female turkeys ends by the beginning of 15th week of life, while in male turkeys it it ends a few days later (by the end of 15th week of life). Point of inflection in male turkeys occurs at the middle of 10th week of life, while in females it occurs at the beginning of the 10th week of life. Asymmetric S – function is best suited for describing turkey growth within the studied regression models