Effect of body weight of goats and lactation order on the growth rate of kids in the suckling period

Abstract

The paper presents results of investigation of milk yield by lactation, by order, and mother's body weight on growth rate of kids of the domestic Balkan goat. Daily weight gains of 376 single kids (168 male and 208 female), in three monthly intervals, and their final body weight at 90 days of age were established. Variability of analyzed traits was presented using descriptive statistics parameters, and differences of growth traits for weight gain of kids resulting from the effect of milk yield of female goats by order of lactation were investigated by single analysis of variance. The effect of independent variables, mothers' milk yield and body weight, on body weight of kids was tested using multiple regression analysis. During the entire suckling period, established average values for kids body weight differed significantly (P (lt) 0.001), increasing from the 1st toward later lactations. At 90 days of age the lowest values were established in kids from the youngest mothers (11.86 kg), while for kids of mothers in the fourth or later lactations these values were higher (13.93 kg). Coefficients of determination indicate that the variability percentage for individual growth traits of kids was in the 0.08 - 0.17 interval, indicating its significance. Both 'b' coefficients (b1 and b2) are positive and statistically highly significant, except for coefficient b2 in the analysis of body weight of kids at birth. The positive sign and high statistical significance indicate a pronounced effect of mother's milk yield and body weight on the body weight of kids up to 90 days of age.

U ovom radu prikazani su rezultati ispitivanja uticaja količine mleka u laktaciji po redu, i telesne mase majke na porast jaradi domaće balkanske koze do 90 dana. U cilju ispitivanja razvoja telesne mase jaradi u zavisnosti od količine mleka u laktaciji po redu u toku dojnog perioda ukupno je izmereno 376 jaradi jedinaca (168 muških i 208 ženskih). Varijabilnost analiziranih osobina je prikazana parametrima deskriptivne statistike, dok su razlike u osobinama porasta jaradi koje su nastale pod uticajem mlečosti koza u laktaciji po redu, ispitivane jednostrukom analizom varijanse. Višestruko regresionom analizom ispitivan je uticaj nezavisno promenljivih veličina, mlečnost majke i telesna masa majke, na porast jaradi. Utvrđene vrednosti telesnih masa u toku čitavog dojnog perioda značajno su se razlikovale (P (lt) 0,001) i povećavale od prve ka kasnijim laktacijama, pri čemu su u uzrastu od 90 dana najmanje vrednosti utvrđene kod jaradi od najmlađih koza (11,86 kg), dok su kod jaradi čije su majke bile u četvrtoj i kasnijim laktacijama te vrednosti iznosile 13,93 kg. Koeficijenti determinacije ukazuju na to da se procenat varijabilnosti pojedinih osobina porasta jaradi nalazio u intervalu od 0,08 do 0,17, što ukazuje na njihovu značajnost. Oba 'b' koeficijenta (b1 i b2) su pozitivna i statistički visoko značajna, osim koeficijenta b2 u analizi telesne mase jaradi pri rođenju. Pozitivni predznak i visoka statistička značajnost ukazuju na izražen uticaj mlečnosti i telesne mase majki na porast jaradi do 90 dana.