Daria Murawska

Age-related changes in the distribution of lean, fat with skin and bones in duck carcases.

1. The experimental birds were Pekin ducks (352 and 352) reared to the age of 13 weeks. They were fed standard diets ad libitum. Starting from the second week, 21 males and 21 females were slaughtered every 7 d. Their carcases were divided into the following elements: neck, wings, legs, breast and back, which were then dissected into lean, skin with fat and bones. 2. The body weights of one-day-old ducklings were similar (circa 62 g), but at 5 weeks of age the males were heavier than the females, and at 13 weeks of age their body weights were 3537 g and 2994 g, respectively. 3. In 2-week-old ducks 55·77% of lean was located in the legs, 15·91% in the back part, 2·78% in the wings, 12·47% in the neck and only 13·12% in the breast. 4. Considerable changes in the distribution of lean were noted in the ducks aged 7 weeks. Its percentage decreased in the legs (to 29·34%) and increased in the breast and wings (to 36·86% and 10·96%, respectively). 5. Age-related changes in the distribution of skin with fat were smaller. Its percentage increased in the wings, legs and back, and decreased in the neck and breast. 6. Until the age of 7 weeks the percentage of bones was decreasing quickly in the legs and increasing in the neck and breast, compared with their total weight in the carcase.

The effect of age on the growth rate of tissues and organs and the percentage content of edible and nonedible carcass components in Pekin ducks

Age has a significant effect on carcass tissue composition, which is an important consideration in slaughter animals because age-related changes are observed in both edible and nonedible carcass components. In this study, the above changes were analyzed in Pekin ducks. The weight of individual edible and nonedible components in ducks increased for different periods of time, and the growth rate of tissue components varied considerably. The percentage content of edible components in the total BW of Pekin ducks increased from 42.8% in wk 1 to 59.9% in wk 8, mostly due to a significant (13.3%) increase in the share of muscle tissue. The percentage content of skin and subcutaneous fat remained at a stable level from wk 4, whereas the share of giblets decreased from 6 wk of age. The percentage content of nonedible components in the total BW of Pekin ducks decreased from 48.6% in wk 1 to 34.6% in wk 8, mainly due to a decrease in slaughter offal content (from 39.7% in wk 1 to 27.2% in wk 8). Minor changes were noted in the proportion of bones (11.7% in wk 1 and 10.9% in wk 8).

Age-related changes in the percentage content of edible and nonedible components in turkeys

The total percentage content of edible and nonedible components in the carcasses of different poultry species is an important economic consideration. Age has a significant effect on the growth rate of birds and carcass tissue composition. The objective of this study was to determine age-related changes in the percentage content of edible and nonedible components in turkeys. The experimental materials comprised 2-wk-old Big 6 turkeys, raised to 20 wk of age (males) and 16 wk of age (females). The percentage content of edible components increased, and the percentage content of nonedible components decreased with age. The percentage content of edible components increased by approximately 20% in males (from 2 to 20 wk) and 25% in females (from 2 to 16 wk). At slaughter, 20-wk-old males were characterized by a higher content of edible components, compared with 16-wk-old females, because at 2 wk of age the proportion of nonedible components was 13.2% higher in females than in males. Among edible components, the content of muscle tissue and skin with subcutaneous fat increased, and the content of giblets decreased. The share of muscle tissue in the total BW of males and females increased by 20.5 and 21.9%, respectively. The share of skin with subcutaneous fat increased by 3.5% in males and 5.8% in females. The proportion of giblets decreased by around 4% in both males and females. The decrease in the percentage content of nonedible components was mostly due to a decrease in the share of slaughter offal (by 14.5% in males and 18.9% in females), accompanied by minor changes in the proportion of bones (by 4.1% in males and 2.1% in females).

The effect of age on the growth rate of tissues and organs and the percentage content of edible and inedible components in Koluda White geese

The parts of carcasses of slaughtered animals that are not intended for human consumption are referred to as inedible components. The total percentage of edible to inedible components in the carcasses of different poultry species is an important economic consideration. The objective of this study was to determine the effect of age on the growth rate of tissues and organs and the percentage change in edible to inedible components in geese. A flock of 240 Polish Koluda White geese was raised to 12 wk of age. The percentage content of edible components increased (P < 0.001) and the percentage content of inedible parts decreased (P < 0.001) as the birds grew older. Among edible components, the most considerable changes were noted in the growth rates of muscle tissue (10.5% increase; P < 0.001) and giblets (5.1% decrease; P < 0.001). The percentage share of muscle tissue increased to 10 wk of age. Lean meat weight increased from 175 g in wk 2 to 1,482 g in wk 12. The increase in lean meat weight varied considerably between body parts. The proportion of breast muscles in total meat weight increased substantially (by 26%), whereas the proportion of leg muscles decreased (by 34%). An increase in the weight of skin with subcutaneous fat was observed until the end of the rearing period, but the percentage content of this component remained at a similar level throughout the experiment (19.1 to 19.6%). The decrease in the percentage content of inedible components was mostly due to a decrease in the share of slaughter offal (by approximately 6.5%) because the proportion of bones remained at a stable level (approximately 11.9 to 11.5%). The weight of abdominal fat, which can be classified as edible or inedible, increased significantly with age, from 15.1 g in wk 2 to 205.1 g in wk 12, accounting for 1.6% and 4.0% total BW, respectively.

Effects of caponization and age on the histology, lipid localization, and fiber diameter in muscles from Greenleg Partridge cockerels

&NA; The preference of modern consumers for high‐quality meat has forced breeders to use native breeds to produce capons. Caponization, both chemical and surgical, leads to androgen deficiency and changes in lipid metabolism and results in the accumulation of abdominal, subcutaneous, and intramuscular lipids, which change the sensory values of the meat. The aim of this study was to histologically evaluate selected skeletal muscles from Greenleg Partridge capons and cockerels. We examined lipid localization in the muscular tissue and also assessed both fiber type and fiber diameter in the pectoral muscles. The experiment was performed on 200 Greenleg Partridge cockerels and testes were removed at 8 wk of age. At 12, 16, 20, 24, and 28 wk of age, 6 cockerels and 6 capons were slaughtered, and samples from the pectoral and thigh muscles were evaluated. Our histopathological evaluation revealed only minimal changes, and no significant differences between capons and cockerels were observed. The pectoral and thigh muscles of the capons had higher concentrations of lipids around the blood vessels, in the perimysium, in the endomysium, and in the sarcoplasm. The analysis of fiber type in the Pectoralis major muscles revealed that the fibers were all the IIB type. The diameters of the fibers of the pectoral muscles were significantly different (P < 0.05) at 20, 24, and 28 wk of age, and diameters of the giant fibers were significantly different (P < 0.05) at 24 and 28 wk of age. High concentrations of lipids in the meat of the capons is undesirable due to health‐related reasons. However, the ability of adipose tissue to improve the sensory values of meat will always be a major quality of native/traditional products.

Alternative growth functions for predicting body, carcass, and breast weight in ducks: Lomolino equation and extreme value function

In this study, 2 alternative growth functions, the Lomolino and the extreme value function (EVF), are introduced and their ability to predict body, carcass, and breast weight in ducks evaluated. A comparative study was carried out of these equations with standard growth functions: Gompertz, exponential, Richards, and generalized Michaelis-Menten. Goodness of fit of the functions was evaluated using R(2), mean square error, Akaike information criterion, and Bayesian information criterion, whereas bias factor, accuracy factor, Durbin-Watson statistic, and number of runs of sign were the criteria used for analysis of residuals. Results showed that predictive performance of all functions was acceptable, though the Richards and exponential equations failed to converge in a few cases for both male and female ducks. Based on goodness-of-fit statistics, the Richards, Gompertz, and EVF were the best equations whereas the worst fits to the data were obtained with the exponential. Analysis of residuals indicated that, for the different traits investigated, the least biased and the most accurate equations were the Gompertz, EVF, Richards, and generalized Michaelis-Menten, whereas the exponential was the most biased and least accurate. Based on the Durbin-Watson statistic, all models generally behaved well and only the exponential showed evidence of autocorrelation for all 3 traits investigated. Results showed that with all functions, estimated final weights of males were higher than females for the body, carcass, and breast weight profiles. The alternative functions introduced here have desirable advantages including flexibility and a low number of parameters. However, because this is probably the first study to apply these functions to predict growth patterns in poultry or other animals, further analysis of these new models is suggested.

Use of a modified skin slice with subcutaneous fat and carcase weight without this slice for prediction of meatiness and fatness in young slaughter geese

1. White Italian geese (40 males and 40 females) were reared until 12 weeks of age and fed standard diets ad libitum. After rearing ended, the geese were weighed (males–5216 g, females–4945 g) and killed. Carcases were chilled and skin slices with subcutaneous fat removed. The remaining part of the carcase was dissected into meat, intermuscular fat and bones. 2. The weight of a skin slice with subcutaneous fat, taken from the carcase surface excluding the forewings and wing tips (X 2), and the weight of a carcase excluding this slice, the forewings and wing tips (X 1) were very good indicators of the content of skin with fat (r > 0·99) and meat (r > 0·98) in a whole carcase. 3. The above traits provided a basis for deriving regression equations to estimate the content of meat (Ŷ) or skin with subcutaneous and intermuscular fat (Û) in whole carcases of White Italian geese. The following equations are recommended for practical application: Ŷ = 0·755X 1 – 27·8 (Sy  = 26·3 g); Û = 1·070X 2 + 19·5 (Su  = 11·4 g)

Carcass characteristics, meat quality, and fatty acid composition of wild-living mallards (Anas platyrhynchos L.)

Abstract The aim of this study was to determine the carcass characteristics, meat quality, and fatty acid composition of wild‐living mallards. The experimental materials comprised 30 mallards (1:1 sex ratio) harvested during the hunting season in northeastern Poland. The carcasses were transported to the laboratory where they were weighed individually, plucked, dressed, and dissected. The proximate chemical composition and physicochemical properties of meat and the fatty acid profile of breast muscle lipids were determined, and a histological analysis was performed. Body weight (BW) and carcass weight were higher in males than in females (P ≤ 0.05), whereas the percentage share of carcass tissue components was similar in both sexes. Edible components accounted for approximately 60% (♂) to 60.7% (♀) of the total BW of mallards, including lean meat; 40.9% (♂) to 41.5% (♀), skin with subcutaneous fat; 10.7% (♂) to 10.8% (♀), and giblets; 8.3% (♂) to 8.4% (♀). Breast muscles had high protein content (23.51%♀ to 23.6% ♂) and low fat content (0.82% ♂ to 0.84% ♀). In the fatty acid profile of breast muscle lipids, saturated fatty acids (SFA) accounted for 39.1% (♂) to 39.04% (♀), monounsaturated fatty acids (MUFA)—for 17.31% (♂) to 17.33% (♀) and polyunsaturated fatty acids (PUFA)—for 43.61% (♀) to 43.64% (♂). The diameters of type IIA and type IIB muscle fibers were lower in males than in females (P ≤ 0.05), whereas lipid storage sites in muscles were similar in both sexes. The values of cooking loss (CL), water‐holding capacity (WHC), pH24, and color parameters of breast meat were comparable in males and females. The results of this study indicate that wild‐living mallards, both males and females, are characterized by high meat quality, and that seasonal mallard harvests can provide meat with desirable eating attributes, attractive to consumers.

Effects of caponization and age on the histology, lipid localization, and fiber diameter in muscles from Leghorn cockerels

ABSTRACT Poultry researchers seek general and native lines of birds for capon production. The primary aim is to find high‐quality meat with valuable sensory attributes. Castration decreases androgen levels and changes lipid metabolism, resulting in the accumulation of abdominal, subcutaneous, and intramuscular fat, which changes the flavor, texture, and tenderness of the meat. Histological analysis of selected skeletal muscles from Leghorn capons and cockerels was the main aim of the present study, along with examination of lipid localization in muscle tissue. We also assessed fiber type and diameter in the pectoral muscles (pectoralis major). The experiment was performed on 200 Leghorn cockerels; testes were removed at 8 wk of age. At 12, 16, 20, 24, and 28 wk of age, 6 cockerels and 6 capons were slaughtered, and samples from the pectoral and thigh muscles were evaluated. Differences in the focal necrosis of the fibers with infiltration of lymphoid cells (P < 0.05) were observed in thigh muscles, with higher numbers in cockerels than in capons. All examined locations in the pectoral and thigh muscles of capons (around the blood vessels, in the perimysium, in the endomysium, and in the sarcoplasm) showed higher concentrations of lipids compared to levels in cockerels. The analysis of fiber type in pectoralis major muscles revealed that all fibers were type IIB. The diameters of the fibers of the pectoral muscles were different (P < 0.05) at 28 wk of age, and the diameters of the giant fibers were different (P < 0.05) at 16 wk of age. The high concentration of lipids in the skeletal muscles of Leghorn capons is remarkable. Thus, ethical reasons as well as economic reasons should be considered when one‐day‐old cockerels are eliminated.

The Effect of Different Dietary Levels and Sources of Methionine on the Growth Performance of Turkeys, Carcass and Meat Quality

Abstract The aim of this study was to determine the effect of different dietary levels and sources of methionine (Met) on the growth performance of turkeys, carcass and meat quality. A total of 816 Hybrid Converter turkeys in 6 groups and 8 replications were fed wheat-soybean meal-based diets supplemented with three sources of Met: DL-isomer, L-isomer and DL-hydroxy analog (DLM, LM and MHA, respectively). In four 4-week periods (from 1 to 16 weeks of age), the Met content of turkey diets corresponded to the level recommended by NRC (1994) or was increased by approximately 50% to match the intake recommended by some breeding companies. Increased dietary Met content resulted in a higher final body weight (BW) of turkeys (P=0.002) and a lower feed conversion ratio (FCR) (P=0.049), but had no effect on carcass dressing percentage and most parameters of carcass quality. The higher dietary Met level contributed to a decrease in meat pH, a lower contribution of redness and a smaller muscle fiber diameter (P=0.028, P=0.040 and P=0.004, respectively). The higher dietary Met level had no influence on the redox status of meat, but it reduced the incidence of lymphoid cell infiltration between muscle fibers threefold (P=0.003). Throughout the experiment, no significant differences were noted in the growth performance parameters of turkeys, irrespective of Met source. MHA contributed to higher abdominal fat content, lower dry matter (DM) content and lower catalase (CAT) activity in breast meat, compared with DLM and LM. Increased dietary Met content, approximately 50% higher than that recommended by NRC (1994), regardless of Met source, led to higher final BW of turkeys, but had no effect on carcass dressing percentage and most parameters of carcass quality.