ESTIMATES OF MEATINESS ON LIVE ANIMALS IN SHEEP

A total of 50 lambs of four different genotypes were included in obser vation (Tab. 1); they had just finished 60-day test fattening. The ave rage age of lambs at the moment of filling the progeny testing station was 96.7 days and average live weight was 19.90 kg. Differences betwe en the genotypes were large, particularly in the age of the animals (T ab. 1). In the course of testing the lambs were divided into groups of ten animals each according to the breed and they received concentrate diet and hay. The average live weight of lambs at the end of test fat tening made 33.66 kg (s.d. = 4.53 kg). Meatiness of leg, loin and chuc k and fattiness were classified subjectively in the lambs at that time (five-point scale), and these body measures were determined: withers height, body length, chest girth, rump width. Ultrasound was used to m ap the distribution of adipose and muscular tissue on the back by mean s of an echocamera Aloka SSD 210 DX II with the probe UST 58131-5 (5 M Hz), between the 10th thoracic and 1st and 3rd lumbar vertebrae, both on the right and left side of the back. The photographs of the ultraso und were analyzed twice and the section areas of dorsal muscles (MLD), MLD width, largest thickness of MLD and thickness of subcutaneous fat on the back of the lambs were estimated from these photos. Tab. III s hows partial correlation coefficients between the estimations of the u ltrasound pictures and correlation coefficients between the average of ultrasound readings on the right and left side of the back. The repea tability of the reardings of the particular measures in the ultrasound photos was not very high, which documents the necessity of multiple a ssessment of the ultrasound picture to minimize the risk of incorrect interpretation. The low values of correlations between the measurings of fat thickness are conspicuous. It is likely due to the very small a ctual thickness of fat layer. The papers published by other authors ho wever present high values of repeatability coefficients in many cases, especially as for the readings of the thickness of fat layer (Purchas , Beach, 1981; Krauth, 1987). Some indicators of carcass quality were determined in the investigated lambs after slaughter and they were com pared with die estimates of meatiness in vivo. This observation involv ed 47 animals in total (3 lambs which had the weight gain during test by more than 2 standard deviations lower than the average of their bre ed group were eliminated from the set). Tab. II shows average values o f the indicators of fattening performance and carcass quality in the b reed groups of lambs. Besides the indicators of nutrient intake, die d ata were corrected of the effect of systematic factors according to th e following statistical models. 1) For traits determined on live anima ls - equations no. 1: Y(ijl) = mu + PL(i) + VV(j) + h(HM(ijl) - HM) e(ijl). 2) For traits determined after slaughter - equation no 2: Y(ij k) = mu + PL(i) + VV(j) + JAT(k) - h(HN(ijki) - HM) + e(ijkl) where: m u - common constant (general mean) PL(i) - genotype, fixed effect VV(i ) - size of litter the animal comes from, fixed effect JAT(k) - slaugh terhouser in which the animal was slaughtered h - regression factor fo r live weight HM(ijkl)-live weight of 1-th animal at the time of trait determination HM - average five weight of lambs at the time of trait determination Tabs. IV and V show the values of correlations between s ome indicators of the quality of dressed carcass and traits measured o n live animals. Ultrasound measuring of the MLD are at the 1st lumbar vertebra were in the tightest correlation to the value of the MLD area in section behind the last rib where the coefficients of partial corr elation had the values r = 0.592 - 0.612. Partial correlation coeffici ents between the thickness of fat layer in the carcasses and the data determined on live animals were very low. Correlation coefficients bet ween the ultrasound readings of the thickness of fat layer on the back and the percentage of kidney fat showed the large range of values (r = 0.11 - 0.55). It can be stated in general that the values correspond ed to the results of other authors as for the estimates of meatiness o n the basis of MLD area measurings (Krauth, 1987; Nitter et al., 1988) . On the other hand, the estimates of the traits of carcass fattiness were less exact in our case. In order to investigate the suitability o f the traits determined on live animals for meatiness estimates, incre ases in coefficients of determination were calculated in prediction eq uations for estimates of some indicators of carcass quality resulting from inclusion of the traits determined on live animals in the predict ion equations of the general shape: Y(ijkl) = mu + PL(i) + VV(j) + JAT (k) + h(HM(ijkl) - HM) + x(ijkl) + e(ijkl) where: x(ijkl) - value of t he trait determined on live animal. Tab. VI shows the values of these increases. The data demonstrate better usability of the ultrasound mea suring for estimates of some indicators of dressed carcass quality in comparison with other methods of estimations of in vivo meatiness. Mul tiplicative correlations were calculated between the MLD area or thick ness of subcutaneous fat in section behind the last rib and the group of indicators determined on live animals (details see Tabs. VII and VI II). The data demonstrate a suitability of combining the different met hods of meatiness estimates on live animals.