Slaughter value and meat quality of Muscovy ducks, Pekin ducks and their crossbreeds, and evaluation of the heterosis effect AbstractThe studies were conducted on 200 Muscovy ducks, 100 Pekin ducks of the A-44 strain and 200 their crossbreeds (sex ratio: 1:1). The ducks were fed complete commercial diets, appropriate for respective species. Slaughter and slaughter value estimation were performed at the age of: 7 weeks -for males and females of the A-44 strain, 10 weeks -for Muscovy females, and 12 weeks -for Muscovy males and crossbreeds (♂ and ♀). Analysis of the chemical composition, physicochemical properties and sensory properties of meat was made on breast muscles. The heterosis effect on the slaughter value and meat quality was additionally estimated in hybrids. The highest live body weights were reported for Mucovy drakes (4450 g), and the lowest -for ducks from this genetic group (ca. 2400 g). The crossbreeds were characterized by average body weights (2980 g), but the highest relative meatiness (ca. 54%) and the lowest fatness (ca. 20%) of carcasses. The best sensory properties were reported for muscles of ducks of the A-44 strain. A favorable heterosis effect was observed in crossbreeds: positive in relation to meatiness and negative in relation to fatness, undesirable in the customers' opinion. No favorable heterosis effect was noted in most meat quality traits.

The aim of the present study was to derive multiple regression equations for in vivo estimation of the carcass lean and fat content in Muscovy ducks. The experimental materials consisted of 240 White Muscovy ducklings (120 male and 120 female). One hundred sixteen females aged 10 wk and 112 males aged 12 wk were slaughtered. Before slaughter the ducks were weighed, and the following body measurements were taken: humerus length, drumstick length, chest girth, breast-bone crest length, width between the humeral bones, chest depth, and breast muscle thickness. The coefficients of simple correlation between carcass tissue components and body measurements were calculated. It was found that live body weight was highly correlated with the weights of all tissue components (r = 0.701 to 0.857). In males a significant interrelation was found between breast muscle weight and all body measurements, whereas in females breast muscle weight was correlated with breast-bone crest length, chest girth, width between the humeral bones, chest depth, and breast muscle thickness only. In both males and females the carcass lean content was closely correlated with drumstick length, breast-bone crest length, chest girth, and width between the humeral bones. In drakes the carcass fat content was closely correlated with all body measurements, whereas in hens significant correlations were observed between the carcass fat content and chest girth, width between the humeral bones, and chest depth only. The coefficients of simple correlation between the percentages of carcass tissue components and body measurements were generally low and statistically nonsignificant. Twelve multiple regression equations formulated based on the body measurements of live ducks were verified with respect to the accuracy of estimation of the content of breast muscles, meat, and fat with skin in the carcass. These equations give small SE of the estimate (Sy = 23.3 to 83.8 g), high values of coefficients of multiple correlation between the dependent variable and the set of independent variables, and high values of determination coefficients.

The experiment was performed on 60 French lop rabbits raised under extensive conditions and sacrificed at body weight of about 3 kg. It was found that the best indicators of meat weight (g) in rabbit carcasses were body weight, head width and lower thigh length among the traits measured in vivo, and carcass weight, chest girth and thigh circumference among the traits measured post mortem. In vivo prediction of saddle meatiness may be based on body weight, trunk length and thigh length, whereas post-slaughter estimation – on carcass weight, hip circumference and thigh circumference. Total meat weight in the hind half of the carcass may be predicted in vivo on the basis of body weight, head width and lower thigh length, and post mortem – on the basis of carcass weight, chest girth, hip circumference, thigh circumference and pelvic width. Multiple regression equations for meat weight estimation in the whole carcass and its middle and hind part were derived in the study. These equations may be applied in selection work directed towards an improvement in carcass meatiness. They may also be used to evaluate the results of experiments conducted on French lops.  

Abstract. The purpose of this work was to determine the effect of the body weights of day-old Muscovy ducklings on some slaughter value traits of females aged ten weeks and males aged twelve weeks. The relationships between the body weights of day-old ducklings, daily gains and slaughter value of grown-up ducks were also analyzed. The experimental materials comprised 96 White Muscovy ducklings (46 ♂ and 50 ♀). Males and females were reared separately, to twelve and ten weeks of age respectively. At the completion of the rearing period the birds were fasted for 12 hours and sacrificed. The carcasses were chilled, weighed and subjected to a detailed dissection. Before statistical calculations were carried out, males and females were divided into five weight groups, depending on their body weights on the first day following hatching. At the end of the experiment it was found that the grown-up ducks once classified as light, medium-heavy and heavy ducklings did not differ significantly in terms of body weight, mean daily gains, carcass weight, as well as the weight and percentage of particular tissue components in a carcass. Low and statistically non-significant values of the coefficients of simple correlation and regression suggest a lack of interdependences between the body weights of day-old ducklings and the slaughter value parameters of adult Muscovy ducks. The only exception was the carcass dressing percentage of males, which was found to be significantly negatively correlated with their body weights on the first day of life.

Abstract. The objective of this study was to determine relationships between breast muscle thickness measured by ultrasonography and meatiness and fatness characteristics in broiler chickens. The experiment was conducted on 80 Ross 308 chickens aged 42 days. Breast muscle thickness was determined before and after slaughter, using an ultrasonic diagnostic apparatus (Dramiński Animal Scanner with an abdominal, sector mechanical probe). The chickens were weighed and carcasses were subjected to detailed dissection. In males breast muscle thickness measured before slaughter was found to be statistically correlated with the weight of a carcass, meat and breast muscles as well as with the percentage content of breast muscles in the carcass. The same measurement taken after slaughter showed a high correlation with all analyzed traits except for the percentage content of fat with skin in the carcass. The coefficients of correlation between the analyzed traits, characterizing meatiness in females, were in most cases slightly higher than in males.