Predicting the Weight of Holstein-Friesian Males at Different Ages by some Body Measurements

Abstract

This study was conducted in one of the private fields for breeding Holstein-Friesian calves in the village of Al-Hamad in Al-Diwaniyah Governorate, where 107 males were used, including 21 at the age of 1 year, 51 at the age of 2 years, and 35 at the age of 3 years. The animals were weighed with an electronic scale, and body measurements (height body, chest girth and hip girth in centimeters) and the study aims to find the best single or double size to estimate the body weight of Holstein Friesian males, and the results of the current study can be summarized as follows: It was found that age had a highly significant effect (p<0.01) on body weight and its measurements, as it increased with age, as the weights of Holstein Friesian males, aged 1, 2, and 3 years, for all ages reached 271.714, 359.627, 522.914, and 395.785 kg, respectively. Age also had a significant (p<0.01) effect on measurements of body length, chest and hip girths, and the correlation coefficients ranged between body measurements for males and for the sum of ages between 0.887 to 0.988. In this study, it was found that the best measure for estimating body weight is chest and hip girth, as the correlation coefficients between body weight and chest girth ranged between 0.845 to 0.965, and between weight and chest girth from 0.831 to 0.970. And that the best equation for estimating the body weight of bulls at the age of one year is the chest girth as a single measurement if the regression equation Y=-76.791+1.280GC. The coefficient of determination, R2 = 0.930, with a standard error of the estimate 5.59. As for the best equation for estimating the weight of bulls at the age of 2 years, it is based on the girth of the chest, as the determination reached R2 = 0.715, and the regression equation Y=-348.104+4.206CG. With a standard error of the estimate 25.625. And the girth of the hip, as the coefficient of determination was 0.753 = R2 and the regression equation y = - 431.986 + 4.647 CG. And with a standard error of the estimate 23.838. The best equation for estimating the weight of bulls at the age of 3 years is to rely on chest girth as a single measure and the regression equation. Y=-451.388+5.05 CG, And the determination equation is R2 = 0.877, with a standard error of the estimate 20.518. As for the regression equation to estimate the body weight of bulls and for all ages, the equation of dependence on the girth of the chest can be used Y=-610.582+5.813 CG. Where it was R2= 0.931 with a standard error of estimation was 27.936 or depending on the girth of the hip Y = -632.404 + 5.884 CG, where R2 = 0.941 HG and with a standard error of estimation was 25.725.