Effects of age and sex on the structural, chemical and technological characteristics of mule duck meat

1. The aim of the study was to analyse the effect of age and sex on the chemical, structural and technological characteristics of mule duck meat. 2. Ten males and 10 females were weighed and slaughtered at 8, 10, 11, 12 and 13 weeks of age. Weight, pH value, colour, tenderness and juice loss of breast muscle were determined. 3. The activities of 3 enzymes (citrate synthase, beta-hydroxyacyl CoA dehydrogenase, lactate dehydrogenase) which indicate muscular metabolic activity were assayed. 4. Chemical composition (moisture, lipids, proteins, minerals, lipid and phospholipid classes, fatty acid composition) of breast muscle was analysed. 5. Fibre type, fibre type percentage and cross-sectional areas were determined using histochemistry and an image analysis system. 6. For growth performance and muscular structure, the ideal slaughter age of mule ducks is 10 weeks of age. Chemical and technological analysis indicated that muscular maturity in Pectoralis major was reached at 11 weeks of age, but, at this age, breast lipid content is high. Moreover, after 10 weeks of age, food costs rapidly increased. 7. Lastly, sexual dimorphism for body weight is minor. In this study, at any given age, no significant differences between males and females were shown. Thus, it is possible to rear both sexes together and to slaughter them at the same age.     

Nutrient supply enhances both IGF-I and MSTN mRNA levels in chicken skeletal muscle

Nutrient supply may control muscle growth directly and indirectly through its influence on regulatory factors. The present study focuses on its effects on muscle insulin-like growth factors (IGF-I and -II) and myostatin (MSTN). Their mRNA levels were quantified by real time RT-PCR in pectoralis major (PM) and sartorius (SART) muscles from broiler chickens submitted to different feeding regimens (fed or fasted for 48 h) between hatch and 2 days of age and at 4 weeks of age. In the PM of 4 weeks old broilers, mRNA levels were also evaluated after a 16 h-fast and a refeeding period (refed 24 or 48 h after a 48 h-fast). In the PM muscle, both IGF-I and MSTN mRNA levels increased between 0 and 2 days of age in the fed group, while they remained low in the unfed one. A comparable trend was observed in the SART, but with lesser amplitude. In both muscles of 4 weeks old chickens, a 48 h-fast induced a significant reduction in MSTN mRNA levels (20% of fed state). In the PM, this effect required more than 16 h of fasting to occur and was fully reversed by only 24h of refeeding. IGF-I mRNA levels also varied with nutritional state. They decreased significantly with fasting in the SART muscle. By contrast, IGF-II mRNA levels did not vary significantly. Our data shows for the first time that two major paracrine regulators of muscle growth, IGF-I and MSTN, are sensitive to nutrient supply in hatching chicks, and also that fasting reduced IGF-I and MSTN mRNA levels in muscles of older chickens.     

Growth and sensory characteristics of organically reared broilers differing in strain,sex and age at slaughter

Abstract

The effects of strain, sex and age on live weight, slaughter weight and sensory characteristics of organically reared broilers in orchards are presented. A total of 450 broilers of three different strains (I 657, Light Sussex, New Hampshire) were reared in an organic research orchard. Half of each strain was slaughtered at 91 days and the other half at 120 days. All broilers were weighed and a clinical welfare assessment was made at slaughter. A trained sensory panel evaluated the breast meat in relation to flavour, smell and texture characteristics defined by the panel. At both 91 and 120 days of age the commercial breed I 657 was significantly heavier than the slower growing strains. Males were significantly heavier than the females across strains. Weight ratios between males and females were nearly the same at both slaughter ages in I 657, whereas weight ratios increased significantly at 120 days in Light Sussex and New Hampshire. No overall effect of strain was found on the flavour and smell of the breast meat. However, the age-related changes in tenderness and toughness differed significantly between strains, since the commercial strain tended towards a tougher and less tender consistency with age, whereas the opposite was the case for the slower growing pure breeds. The positive flavour of salt was significantly improved at 120 days across strains with females having a saltier flavour than the males with age. The positive flavour of sweet corn was improved in the meat from the males, whereas the positive smell of sweet corn was significantly improved in both males and females. No negative effects of age were found.

In conclusion, broilers were tastier when slaughtered at 120 days compared with 91 days. The development in meat tenderness was related to strain, and weights at slaughter were related to both strain and sex.     

Relative responses of protein turnover in three different skeletal muscles to dietary lysine deficiency in chicks 1

1. The effect of lysine deficiency was analysed on muscle protein turnover in 2‐, 3‐ and 4‐week‐old growing broilers. Protein fractional synthesis rates (FSR, in %/d) were measured by a reliable in vivo technique (flooding dose of L‐[4‐³H] phenylalanine) in the Pectoralis major (PM), the Anterior latissimus dorsi (ALD) and the Sartorius (SART) muscles. Protein fractional breakdown rates (FBR, in %/d) were estimated as the difference between the synthesis rates and the growth rates of tissue protein.

2. Lysine deficiency resulted in significant increases in muscle FSR and FBR. When expressed in absolute rates (g/d), tissue protein deposition was reduced whatever the tissue. This phenomenon was accompanied by decreased protein synthesis (ASR).

3. The protein turnover responsiveness to the lysine deficiency appeared to depend on the studied muscle, since the PM muscle was the most sensitive whereas the SART and ALD muscles presented a lower sensitivity.     

Analysis of growth curves of fowl. II. Ducks.

1. Growth curves of nine selected lines and one random-bred control population (in total, n = 1070) were evaluated by the Richards function. The ducks were weighed at 7-d intervals and, after the tenth week, every second week (up to 18 weeks). Food and water were supplied ad libitum. 2. The predicted curves closely fitted the weight data points (R2 = 0.9991-0.9997). 3. The ducks are characterized by early maturity rate. The peak of the absolute growth rate (the inflection point of the curve) occurred at 24.1-27.6 d of age (t+). A higher ratio of the inflection to the asymptotic weights (y+/A = 0.380-0.424) was found in comparison to those from the Gompertz-type function of growth (y+/A = 0.368). 4. In the selected lines the degree of maturity at a slaughter age of 7 weeks (u7 = y7/A) ranged from 0.784 to 0.835 for males and from 0.819 to 0.889 for females. 5. Ducks within the non-selected control line had a significantly lower maturing rate than the selected lines. 6. Sexual dimorphism was recorded for all growth parameters analysed. Females have faster maturation rate than males (higher values of y+/A, u7, k and a shorter auto-acceleration phase of growth). 7. High interline differences were found for body weight (A, y+, y7) and for absolute growth rate (v, v+) and smaller ones for parameters of the maturation rate (y+/A, u7, k and t+). 8. The intragroup phenotype correlation between growth parameters and the use of weight data only up to 7 weeks of age for the estimation of parameters of the Richards function are discussed.     

Macromolecular composition of fast, slow and cardiac muscles of chick during incubation.

Total muscle mass increases about five-fold in fast (anterior latissimus dorsi: ALD) and slow (posterior latissimus dorsi: PLD) muscles and 30-fold in cardiac muscle between the 12th and 20th d of incubation. 2. Increase in muscle protein does not parallel the rise in muscle RNA. 3. The DNA concentration of the ALD muscle decreases while that of the heart and PLD muscle show an increase between 8 and 12 d and a steady decrease thereafter. 4. The increase in glycogen concentration is greater in heart than in ALD and PLD up to the 20th d; 1 d after hatching, ALD has more glycogen than PLD.     

Effect of genotype, sex and rearing temperature on carcase and meat quality of guinea fowl

1. The aim of our study was to analyse the effect of genotype (label and standard), sex and rearing temperature (simulating daily outdoor in the summer or winter) on the carcase and meat quality of guinea fowl. Using 20 animals per treatment, slaughtered at 96 d of age we measured the breast angle and the thickness of the skin on the wing membrane. Carcases were weighed and cut into parts according to a standardised procedure to determine the percentages of abdominal fat, breasts, wings and thighs with shanks. 2. At slaughter, standard guinea fowl were heavier than label guinea fowl and for both genotypes, the females were heavier than the males (+5.6%). The mean value of breast angle was 85 degrees. This value was significantly higher for the standard guinea fowls and for the females of both genotypes compared with males. Thus, female carcases, particularly standard females, were more compact. The skin was thicker for the standard guinea fowls (0.84 mm vs 0.77 mm) which could be due to more subcutaneous fat. 3. Carcase yield was higher for the males (68.7% vs 68.2%). The percentage of abdominal fat was higher for the standard guinea fowls (2.8% vs 2.4%) and for the females of both genotypes compared with males. The label guinea fowls had higher yields of breasts and thighs with shanks. For both lines, the breast and thigh meat of females was judged more tender and less stringy. 4. Low rearing temperature decreased growth performance but had no significant effect on carcase quality.     

Age-related changes in the intramuscular distribution of melanocytes in the Silky fowl

1. The characteristics of melanocyte distribution in skeletal muscles in the Silky fowl were investigated in association with growth. 2. Pectoralis (PT) and iliotibialis lateralis (ITL) muscles from 1-, 3-, 5-, 10-, 20- and 30-week-old Silky males were weighed and collagen type I was detected in frozen sections immunohistochemically. 3. Melanocytes were observed in the collagen type I-immunopositive endomysium and perimysium in both muscles. 4. Image analysis indicated that the total area occupied by melanocytes in histological sections sharply decreased from 0.61% to 0.16% in PT muscle and from 1.67% to 0.33% in ITL muscle at 1 to 3 weeks, and then gradually decreased. The melanocyte area was larger in ITL muscle than in PT muscle until 10 weeks of age. 5. We concluded that the proportion of intramuscular melanocytes in the Silky fowl differs between types of muscles in the early stages of development, and it decreases with growth.     

Breeder hen dietary L-carnitine affects progeny carcase traits

(1) Ross 308 broiler breeder hens were given diets containing 0 or 25 mg L-carnitine/kg from 21 weeks of age. (2) Hens were inseminated with semen from Ross broiler breeder males and subsequent growth performance and carcase traits, of progeny obtained from hatches at 30, 35 and 37 weeks of age, were evaluated. (3) Progeny were hatched in a common facility and separated by gender. Experimental treatments employed for the 30-, 35- and 37-week hatches, respectively, were: hen diet and progeny gender (16 replications with two subplots); hen diet, progeny diet (0 and 50 mg L-carnitine/kg of diet) and progeny gender (16 replications with 4 subplots); and hen diet and progeny diet (high and low density; 16 replications with two subplots). (4) Females had lower growth rate and less breast meat, but greater proportions of carcase fat and breast meat than males. Growth performance measurements of progeny were not affected by hen L-carnitine, but hen L-carnitine decreased abdominal fat in progeny. Increasing diet density in the chick diets increased growth and carcase weights. Hen and progeny dietary L-carnitine interacted to increase male mortality. However, dietary hen L-carnitine decreased carcase fat and increased breast meat in progeny fed on high nutrient density diets. (5) In conclusion, L-carnitine in the diet of hens affected carcase traits of their progeny.     

北京鸭部分组织早期生长规律的研究

通过对６个日龄的北京鸭的屠宰和组织分离，发现北京鸭在２８日龄为其主要组织的生长转折点。骨骼、腿肌等主要组织相对屠体重由快速增长在此时变慢，而胸肌则由慢变快。因此建议以２８日龄为界限划分北京鸭的前后生长期，营养和管理的变化也应在此时进行。４２日龄以后主要是胸肌和皮脂的增长，其它组织相对增长缓慢。内脏和脚相对屠体重的比率随日龄迅速下降，到４２日龄以后基本稳定；头颈的相对比率基本上是逐渐缓慢下降的趋势，而皮脂重始终和屠体重基本保持正比的增长速度。     

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

The experimental birds were Pekin ducks (352 males and 352 females) 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. 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. 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. 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). 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. 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.     

湘白鹅生长发育规律及产肉性能的研究

试验旨在研究湘白鹅的生长发育规律及产肉性能。选用雌、雄湘白鹅各50只,分别在0~12周龄称重,利用Logistic曲线方程对雌、雄湘白鹅各周龄的体重变化进行拟合;12周龄时随机挑选雌、雄湘白鹅各8只屠宰,测定体尺指标及产肉性能。结果表明：①湘白鹅1~6周出现体重增长高峰,7~12周相对稳定;4周龄后,雄鹅体重显著（P<0.05）或极显著（P<0.01）高于雌鹅;雌、雄鹅Logistic生长曲线模型的拟合度均高达0.988以上,雌鹅生长曲线拐点为5周龄,雄鹅为5.2周龄;雌、雄鹅4周龄体重与12周龄体重的相关系数分别为0.512、0.561（P<0.01）。②12周龄雄鹅的体斜长、龙骨长、胫长和半潜水长均高于雌鹅,差异显著（P<0.05）。③12周龄雄鹅活重显著大于雌鹅（P<0.05）。④湘白鹅屠宰率、全净膛率、胸肌率和腿肌率分别为88.25%、67.93%、13.03%和13.76%。综合以上结果,湘白鹅生长较快,产肉性能良好,雌、雄鹅生长发育、体尺指标及产肉性能之间存在一定差异,雄鹅优于雌鹅。     

Study on Growth and Development Law and Meat Performance in Xiang White Goose

The study was aimed to reveal the rule of growth and development and meat performance in Xiang White goose. 100 healthy Xiang White geese (50 male and 50 female) were selected and weighed during 0 to 12 weeks of age for study the growth and development by using Logistic model. 8 geese in each gender were slaughtered at age of 12-week and the body size index and meat yield performance were measured. The results showed as follows:① Xiang White goose grew rapidly in 1 to 6 weeks, and the increase of body weight was relatively stable during 7 to 12 weeks. After 4 weeks of age, the body weight of male goose were significantly (P<0.05) or extremely significantly (P<0.01) higher than the female. The fitting rates of Logistic model were over 0.988 in both male and female goose. The inflection of growth curves of female goose was at age of 5 weeks, and the male was 5.2 weeks. The correlation coefficient between the body weights at age of 4 weeks and 12 weeks were 0.512,0.561 in male and female goose, respectively (P<0.01).②The body length, keel length, tibia length and half-length diving of male goose at age of 12 weeks were significantly higher than the female (P<0.05).③The live body weight of male goose at age of 12 weeks was significantly greater than the female (P<0.05). ④The slaughter rate, eviscerated percentage, breast muscle rate, leg muscle rate of Xiang White goose were 88.25%, 67.93%, 13.03% and 13.76%, respectively. In conclusion, Xiang White goose grew fast, and had a good performance of meat production. The growth and development, body size and slaughter performance of male goose were better than the female.     

Downgrading of heavy broiler chicken carcasses due to myodegeneration of the anterior latissimus dorsi: pathologic and epidemiologic studies

Recently, in some Brazilian poultry companies, a dorsal cranial muscular lesion has been increasingly detected in broilers, causing heavy economic losses due to carcass downgrading. The observed gross lesions located in the anterior latissimus dorsi (ALD) muscle are characterized by yellowish discoloration of the skin and swelling on the dorsal cranial region of that muscle. When the ALD muscle is cut, subcutaneous edema, muscular superficial hemorrhage, pallor, adherence, and increased thickness and density are observed. Microscopically, findings indicate degenerative and polyphasic features, variation in fiber size and splitting, presence of hyaline, necrotic and regenerative myofibers, extensive fibrosis, and adipose tissue with lymphohistiocytic infiltration in all ALD muscles affected. The etiology of the lesion is unknown, and no detailed report was found in literature. The highest frequency of carcass downgrading due to this lesion was found in the heaviest and the oldest males of high-yield broiler strains (P < 0.01). This study is the first to describe the pathologic and some epidemiologic aspects of this new myopathy.     

Schistosoma mattheei in the ox: Observations on the parasite

Nineteen Friesian steers infested with between 5 000 and 45 000 cercariae of Schistosoma mattheei were slaughtered at intervals between 7 and 107 weeks post-infestation and the parasites were recovered by perfusion of the blood vessels. Adult parasites were eliminated as infestation progressed, the greatest loss occurring between 18 and 40 weeks. Females in the mesentery became shorter as infestation progressed but males remained unchanged. Males from the gastric veins were sometimes longer than those from the mesentery while males and females from liver and lungs were often shorter. Females from the mesentery contained 0–107 eggs, with a mean of 36, and those from liver and lung contained fewer eggs. The prepatent period was 6–7 weeks. A sharp reduction in faecal egg count between 15 and 25 weeks post-infestation was caused by a reduction in oviposition. The marked changes in the number of parasites present, their length and their egg-laying capacity appeared to be mediated by the immune response of the host and were manifestations of the establishment of a biological equilibrium which limited the pathogenic effects of the parasite.     

Sexual dimorphism in jaw muscles of the Japanese sparrowhawk (Accipiter gularis)

Materials suitable for anatomical research of raptorial birds are rare. Bird‐eating raptors show distinct inter‐sexual differences in body size and parental roles. The large females catch larger prey and prepare small morsels to feed their young using their hooked beaks. Here, we investigated the architectural properties of different jaw muscles of the Japanese sparrowhawk (Accipiter gularis) and examined whether there is sexual dimorphism in their architectural design. The results showed that musculus depressor mandibulae, the opener of the lower jaw, was characterized by relatively long fascicle length, whereas musculus pterygoideus was characterized by its larger mass and physiological cross‐sectional area (PCSA) in both sexes. Females have the potential capacity to produce rapid and strong bites by their significantly longer fascicle length of M. depressor mandibulae and larger mass and PCSA of M. pterygoideus. For body size‐matched gender, jaw muscles of males had fibres of relatively longer length than females, enabling greater velocity and excursion. Architectural characteristics of jaw muscles, together with the absolute dimorphism (the fascicle length of M. depressor mandibulae, the muscle mass and PCSA of M. pterygoideus) and relative dimorphism in the muscle mass of M. pterygoideus, reflect dietary difference and asymmetric parental roles between the sexes.     

不同日龄略阳乌鸡肉品质对比与最佳上市日龄分析

【目的】 探究不同日龄略阳乌鸡肌肉营养成分的差异,为确定最佳上市日龄以及科学养殖提供理论支持。【方法】 试验以同日出雏的1 200只略阳乌鸡为研究对象,随机分为4个重复,每个重复300只。所有鸡42日龄脱温后进行网上笼养,90日龄后为离地网上平养,各阶段的基础饲粮均使用家禽专用饲料,全程自由采食、饮水。记录每周体重,采用Gompertz模型拟合生长曲线;90、120、150日龄时,随机选取体况相近的公、母各8只,采用颈部放血法进行屠宰,采集胸肌,检测不同生长时期胸肌pH、剪切力、水分、干物质、氨基酸、脂肪、蛋白质、肌苷酸和脂肪酸含量。【结果】 略阳乌鸡在1~4周体重增长缓慢,4周后进入急速生长期,到17周后体重增长趋势逐渐减缓;Gompertz模型能够很好地拟合略阳乌鸡体重生长曲线,母鸡、公鸡的拟合度均>0.99,拐点体重分别为760.75和940.52 g,拐点周龄分别为8.19和8.49周。母鸡、公鸡的剪切力均随着日龄的增长而逐渐增大,150日龄均极显著高于90和120日龄（P<0.01）;母鸡胸肌干物质在150日龄极显著高于90和120日龄（P<0.01）。母鸡胸肌的呈味氨基酸中,谷氨酸（Glu）、丙氨酸（Ala）、天门冬氨酸（Asp）含量在150日龄极显著高于90和120日龄（P<0.01）,而酪氨酸（Tyr）的含量在150日龄极显著低于90和120日龄（P<0.05）;苏氨酸（Thr）、丝氨酸（Ser）、蛋氨酸（Met）、亮氨酸（Leu）、赖氨酸（Lys）和总氨基酸的含量在150日龄均显著高于90日龄（P<0.05）。公鸡胸肌的呈味氨基酸中,谷氨酸（Glu）、丙氨酸（Ala）、苯丙氨酸（Phe）、胱氨酸（Cys）、脯氨酸（Pro）含量120日龄极显著高于90日龄（P<0.01）,酪氨酸（Tyr）、胱氨酸（Cys）、脯氨酸（Pro）和苯丙氨酸（Phe）含量120日龄极显著高于150日龄（P<0.01）;组氨酸（His）含量在120日龄最低。120日龄母鸡胸肌的脂肪含量极显著低于150日龄（P<0.01）,120日龄母鸡胸肌的蛋白质含量显著低于150日龄（P<0.05）。母鸡胸肌中亚油酸和肉豆蔻酸含量在150日龄极显著高于120日龄（P<0.01）,棕榈油酸含量在150日龄极显著低于120日龄（P<0.01）。公鸡胸肌的肌苷酸、棕榈酸（C16：0）含量120日龄显著高于150日龄（P<0.05）,而亚油酸含量150日龄显著高于120日龄（P<0.05）。【结论】 随着日龄的增加,略阳乌鸡母鸡营养物质含量逐渐增加;120日龄公鸡胸肌营养物质含量最高,120日龄后随着日龄增加营养物质含量逐渐降低。因此,建议母鸡在120~150日龄之间上市,公鸡在120日龄上市。     

Differential Growth in the Supracoracoideus Muscles of Male and Female Turkeys

The growth of supracoracoideus muscles in male and female turkeys was measured at two week intervals for 20 weeks after hatching. Growth in weight of the supracoracoideus was closely related to growth of the adjacent pectoralis and coracobrachialis muscle. Growth curves for muscle length and fascicular length exhibited marked deceleration so that more than 75% of the length at 20 weeks had been reached by 10 weeks. Growth curves for weight, cross sectional area at the muscle midlength and myofibre diameter were approximately linear with 50% or less of the 20 week growth attainment being reached by 10 weeks. Supracoracoideus muscles in most males had a greater cross sectional area and were longer and heavier than those in females. At 20 weeks, the greater mass of supracoracoideus muscles in males was due to radial and not longitudinal myofibre growth.     

Histopathology of hereditary muscular dystrophy of the domestic turkey (Meleagris gallopavo).

The histopathology of hereditary muscular dystrophy was studied in homozygous dystrophic turkeys of various ages. Myopathy was severe at ten weeks of age but absent at seven weeks or less. Lesions at ten weeks consisted of variation in fiber size and contour with acute necrosis of individual muscle fibers. Myopathic characteristics were similar at 16 and 24 weeks but with fewer dystrophic fibers and slower fiber destruction. Fat deposition was mild at 24 weeks and there were disseminated foci or endomysial proliferation in dystrophic muscle at 16 and 24 weeks. Pectoral and alar muscles were dystrophic but no lesions were detected in gastrocnemius muscle, myocardium, central and peripheral nervous system tissue or visceral organs. Mean diameters and nuclear numbers of muscle fibers were significantly less in pectoral muscles of dystrophic turkeys than in controls and did not have increase significantly from ten to 24 weeks of age as did controls.