THE EFFECT OF NET WEIGHT-GAIN ON THE CARC ASS VALUE OF CZECH PIED CATTLE

Development of variations in the indicators of meat performance of bul ls of Czech Pied cattle was studied in relation to the level of net we ight gain that is determined by potential growth ability of body tissu es and by the effects of external production conditions, mainly by the quality of slaughter animal nutrition. To evaluate the relations of n et weight gain and selected parameters of meat performance the animals were included in three groups according to meat production on bone pe r day of life - net weight gain. The bulls with net weight gain maxima lly 500 g ((x) over bar = 444 g) were included in the first group, tho se with net weight gain from 501 to 589 g ((x) over bar = 545 g) were gut to the second group and those with net weight gain higher than 590 g ((x) over bar = 635 g) to the third group. Net weight gain within t he whole experimental set of slaughter bulls exhibited the variation o f 376 g, with limit values 365 and 741 g. Slaughter weight in the whol e set amounted to 577 kg, with statistically insignificant differences between the groups. An increase in net weight gain was positive with respect to meatiness classification (P < 0.05) and insignificant with respect to the classification of carcass fat distribution. Only an ins ignificant trend of increase in dressing percentage was observed in th e groups with the limit values of net weight gain. The level of net we ight gain did not affect the ratio of hind and fore carcass quarters ( 1.04-1.06), and the ratio of the hind quarters showed the values highe r than 51%. A significant increase in the proportion of internal fat f rom 1.41 to 2.50% (P < 0.01) is considered as a negative feature of th e growth of net weight gain values. More intensive production of inter nal depot fat is however compensated by an increase in meat proportion in the carcass (P < 0.01) to a large extent, which equals +3.90% betw een the first and third group. An increase in the relative proportion of meat is related to a decrease in the percentage of bones in bull ca rcass (P < 0.01). The proportion of separable fat from the surface of sides of beef had very low values (0.61-0.69%), without any important relation to the level of net weight gain. An increase in the proportio n of round and rib meat (P < 0.01) is a positive trend. Changes in the meat and bone proportion in the carcass are related to positive chang es in the meat and bone proportion in the particular quarters and in t he whole carcass. A significant increase in the meat to bone ratio (3. 04-5.07) was observed in the hind quarters (P < 0.01) while the change s in the fore quarters were less significant. The group with the highe st value of net weight gain had the meat to bone ratio 4.93 in the who le dressed carcass; this is a value comparable with the results obtain ed under the same conditions of nutrition not only in Pied breed but a lso in some foreign meat-type breeds.