Abstract:
The aim of this study was to determine the relationship between daily
milk yield and
udder traits using multiple regression analyses in order to predict daily milk yield in
Norduz goats. 10 udder traits including upper udder height, bottom udder height, udder
depth, udder width, udder circumference, left teat length, right
teat length, left teat
circumference, right teat circumference and teat angle. The data was collected from 27
Norduz goats raised in pastoral conditions in the Norduz region of Van province South
Eastern Turkey. Factor analysis was employed to simplify the
complex relationships
between udder traits. After the udder traits were exposed to factor analysis, four factors
with Eigen values greater than 1 were selected as explanatory (independent) variables and
used for multiple linear regression analysis. First
factor was named teat factor, second
and third factors were named udder factors while the fourth was udder bottom height.
The 2
nd
and 3
rd
factors, which were significant, were then used to fit the regression model.
The study found that two udder factors ha
d significant statistical effect on daily milk yield
and these factors together had accounted for 78.6 % of the variation in daily milk yield.
The findings of this study showed that both multivariate and univariate approaches can
be used to determine the r
elationship between milk yield and udder traits. In addition,
these statistical approaches may also be useful to eliminate multicollinearity problems
among large number of variables. In conclusion, the study proved that both univariate
and multivariate met
hods can be applied successfully to predict daily milk yield using
udder traits in goats.
Keywords:
Determination coefficient, Eigen value,
Goats, Milk yield, Udder traits
.
