A. Ponizil et K. Beber, RELATIONSHIP BETWEEN CARCASS COMPONENTS A ND SLAUGHTER WEIGHT OF HEIFERS FROM COMMERCIAL CROSSING, Zivocisna vyroba, 38(9), 1993, pp. 817-826
A dissection was done of carcasses of 111 heifers from commercial cros
sing after fathers of the breeds Aberdeen-Angus (Aa - 7 heads), Herefo
rd (He - 10 heads), Limousine (Li - 34 heads), Charolais (Ch - 29 head
s), Chianina (Ci - 10 heads), Maine-Anjou (Ma - 10 heads), and Blond A
quitaine (Pa - 11 heads); the percentage of meat, bones, and fat has b
een determined and net weight (weight of dressed carcass x coefficient
1,92) calculated. A more detailed description of the initial material
is given in our previous works (P o n i z i l et al., 1993a, b). The
dependence of the variables observed on net live-weight is represented
by Figs. 1 to 5. The values measured were put on the regression strai
ght line with parameters a, b, parameter a being the theoretical value
of the investigated variable in net live-weigh of 500 kg, parameter b
being the increase of the observed variable per each kg above this we
ight. With respect to the number of observations, Tab. I gives values
only for crossbreds with the Charolais and Limousine breeds. Straight
lines in graphs serve only for orientation. Asterisks in the table den
ote values which are statistically significantly different from zero (
P < 0,0 1), index of determination - R2 evaluates the correspondence o
f the values measured with a theoretical model. The quality of estimat
ion is mainly affected by the fact that values of net live-weight are
distributed unevenly (occurrence of distant observations). It can be s
tated that in heifers after Charolais fathers the percentage of meat i
ncreases and the percentage of bones decreases and, at the same time,
meat/bone ratio slightly increases with an increasing net live-weight
(or weight of the dressed carcass). With regard to these facts and in
correspondence with the statement of S a r d i et al. (1986), these cr
ossbreds can be fattened up to the live-weight of 500 to 530 kg. Heife
rs of the Limousine breed show a higher percentage of fat in the half
and a higher meat/fat ratio with increasing live-weight, i.e. the perc
entage of fat increases at the expense of the percentage of meat with
increasing live-weight. We recommend, in correspondence with S a r d i
et al. (1986), to fatten these crossbreds up to a live-weight of 400
to 420 kg. In crossbreds after Hereford fathers, similar tendencies as
in crossbreds with the Limousine breed were found, that means that it
is not appropriate to fatten them to a live-weight exceeding 400 kg.
Daughters after Maine-Anjou and Blond Aquitaine breeds show the same t
endencies as crossbreds after Charolais fathers, including fattening a
bility to a higher slaughter weight. A group of heifers after Chianina
fathers did not show any significant dependences in carcass indexes o
bserved.