蛋重、蛋形指数对孵化率的影响

温度、湿度、二氧化碳浓度是影响孵化率的环境条件,研究较多。衡量种蛋品质的重要指标蛋重和蛋形指数,也可直接影响孵化率,但有关蛋重、蛋形指数影响孵化率的试验研究,目前尚未见报道。1992年,我们就蛋重、蛋形指数和喷水对孵化率的影响作了研究试验,旨在探讨种蛋品质对孵化率的影响规律,以便为进一步提高孵化率提供参考。     

鹧鸪的蛋重和蛋形指数对其孵化率的影响

随着人民生活水平的不断提高,对野味肉食品的需求量也有所上升。人工饲养鹧鸪有生长快,饲养周期短;适应性较强,繁殖率高;成本低,效益高等优点。适合于城市和广大农民养殖,是一条发家致富途径。但是近年来,一些养殖场和珍禽公司鹧鸪的孵化率较低,影响了养殖业的发...     

品种,蛋重及蛋形指数对鹅种蛋受精率和孵化率的影响

以太湖母鹅、川太二元杂交母鹅及莱川太三元杂交母鹅所产种蛋为素材,测定蛋重和蛋形指数,研究其与受精率及孵化率的关系结果表明:品种对受精率及孵化率的影响较大,太湖母鹅所产种蛋的受精率及孵化率最高,其次是川太二元杂交母鹅。在蛋重及蛋形指数对受精蛋的卵化率影响上,三品种均以中间型(平均数加减一个标准差)较高;而蛋重、蛋形脂数对种蛋受精率的影响,三品种的结果不一致。种蛋的受精率和孵化率间存在着强正相关。     

三黄种鸡蛋重和蛋形指数对孵化率的影响

本试验选取３８周龄三黄种鸡蛋９９０枚，分别测定其蛋重和蛋形指数（短径／长径），采用４×４两因子交叉分组设计，将蛋重分成Ａ１（５０　ｇ以下）、Ａ２（５０．１～５５　ｇ）、Ａ３（５５．１～６０　ｇ）和Ａ４（６０．１　ｇ以上）四个水平，将蛋形指数分成Ｂ１（０．７２以下）、Ｂ２（０．７２１～０．７６）、Ｂ３（０．７６１～０．８０）和Ｂ４（０．８０１以上）四个水平，然后进行交叉分组，以研究不同蛋重和蛋形指数对种蛋孵化率的影响。结果表明，蛋重Ａ２（５０．１～５５　ｇ）和Ａ３（５５．１～６０　ｇ）受精蛋孵化率显著高于Ａ１和Ａ４（Ｐ　＜　０．０５），且Ａ２、Ａ３间差异不显著（Ｐ　＞　０．０５）　；蛋形指数在Ｂ２（０．７２１～０．７６）范围内，受精蛋孵化率极显著高于Ｂ１、Ｂ３和Ｂ４（Ｐ　＜　０．０１）。故蛋重在５０．１～６０　ｇ、蛋形指数在０．７２１～０．７６范围内，受精蛋孵化率最高。     

肉鸽种蛋蛋重和蛋形指数对孵化率的影响

本文旨在研究蛋重和蛋形指数对内鸽种蛋孵化率的影响.试验以白羽王鸽为研究对象,共测定了1 122枚种鸽蛋的蛋重和蛋形指数,分析了其与孵化率的相关性.结果表明,蛋重在25～28 g之间,孵化率最高,为88％;蛋重与雏鸽重高度正相关,相关系数为0.827;蛋重越大,雏鸽重越大;但蛋重与失重率则是中度负相关,相关系数为-0.51.蛋形指数在0.65～0.70之间,孵化率最高,为92.95％,高于或低于此范围的孵化率下降.     

蛋形指数,蛋重及比重与孵化率关系的探讨

利用正交试验方法研究了蛋形指数、蛋重及比重三因素与罗曼蛋鸡孵化率的关系。结果表明，蛋形指数是影响孵化率的主要因素，其主次关系是蛋形指数〉蛋重〉比重。蛋形指数７５．１－７８．０％，蛋重５８．０－６０．５ｇ，比重１．０８０－１．０９２是提高孵化率的最优组合。     

贵妃鸡蛋重和繁殖率关系探讨

选２８￣２９周龄贵妃鸡新产种蛋，按蛋重分４组作蛋重和繁殖率关系试验。结果表明，蛋重４１￣４５克组受精率，孵化率和健雏率分别达９８．１１％，９４．２３％和９７．９６％，极显著高于蛋重３０克和３１￣３５克组，４５克内蛋重与三率呈强正相关，小于３０克重组三率极显著低于其它组（Ｐ〈０．０１），试验说明贵刀鸡种蛋最佳蛋重为４１￣４５克，小于３０克的蛋不宜作种用。     

Study of the live body weight and body characteristics of the African Muscovy duck (<Emphasis Type="Italic">Caraina moschata</Emphasis>)

Three hundred and twenty 1-week old ducklings (160 males and 160 females) were used to evaluate the body weight, body parts and carcass characteristics of the African Muscovy duck. Sexual dimorphism was in favour of the male for all the parameters throughout the experimental period, however the difference was significant (P < 0.05) only after week 2. The 12-week old male weighed 1832.0 ± 180.4 g while the female reached only 68.2% of the male weight. Metatarsus diameter, thoracic perimeter, body length, length of bill, foot and wing in cm were respectively 1.3, 29.5, 57.5, 7.0, 27.1 and 27.8 for the male as compared with 1.2, 25.8, 51.0, 6.3, 23.3 and 26.9 for the female. Body measurements were highly (P < 0.01) correlated with body weight for both sexes, however the highest correlation coefficients were obtained with wing length (0.990 and 0.995) and thoracic perimeter (0.993 and 0.973) for female and male respectively. Live body weight had a linear relationship with both wing length (R² = 0.991 and 0.81) and thoracic perimeter (R² = 0.948 and 0.986) for male and female respectively. The female duck yielded higher percent ready-to-cook carcass (66.3%), breast (13.6%), liver (2.8%), heart (1.5%) and gizzard (3.8%) as compared to the male (65.0%, 12.0%, 2.5%, 1.1% and 3.4% respectively) although the difference was not significant (P > 0.05). The male small intestine (185.1 ± 3.4 cm), colon (14.8 ± 1.0 cm) and caecum (17.9 ± 0.4 cm) were significantly (P < 0.05) longer than that of the female (152.2 ± 1.8, 10.8 ± 0.7 and 14.85 ± 0.6 cm respectively).     

Relationship of body condition score, live weight, stocking rate and grazing system to the mortality of Angora goats from hypothermia and their use in the assessment of welfare risks

Body condition scoring is widely used for sheep and cattle but the practice is included in only one Code of Practice for the welfare of goats in Australia. There is no published scientific evidence to support or defend its use in the assessment of welfare risks to farmed goats. PROCEDURE: The significance of stocking rate, grazing system, body condition score (CS) and live weight were investigated in explaining the risk of mortality of individual and flocks of grazing Angora goats from hypothermia following a severe weather event in April. This event occurred 5 weeks after shearing the goats. Angora goats and Saxon Merino sheep were grazed alone, or mixed together in equal numbers at each of three stocking rates. RESULTS: There was no mortality amongst Angora goats provided they grazed at the lowest stocking rate even when their CS was < or = 2.0. Mortality in flocks of Angora goats was most related to the CS reached during the preceding 2 months. For flocks of Angora goats there was no mortality at CS > or = 2.5 and mortality increased sharply at mean CS < 2.0. For individual Angora goats, mortality increased as CS declined and stocking rate and grazing combinations were additive in effect on mortality. Grazing with sheep increased mortality of Angora goats at higher stocking rates. The individual goat mortality rate was not dependent on individual plot effects suggesting that these results are applicable widely. Live weight loss was not related to mortality rates of goats once CS had been accounted for. CONCLUSION: It was concluded that CS and stocking rate were highly significant determinants of welfare risk in Angora goats.     

Relationship of blood corticosterone, immunoglobulin and haematological values in young crocodiles (Crocodylus porosus) to water temperature, clutch of origin and body weight

Objective To examine whether sub-optimal temperature induced stress and immunosuppression in farmed saltwater crocodile (Crocodylus porosus) hatchlings. Design A clinico-pathological study. Animals A total of 140 hatchlings were used. Procedure Body weight and length, plasma corticosterone and immunoglobulin concentrations and total and differential white blood cell counts were measured in 140 hatchlings from five clutches divided between five water temperature treatment groups. Initially all groups were housed at 32°C for 10 weeks, then two groups (L, LC) were changed to low temperature (28°C) and two groups (H, HC) to high temperature (36°C), while one group (C) remained at 32°C. The LC and HC groups were maintained at these temperatures for 10 days, after which the water temperature of both groups was returned to 32°C. Blood samples were collected twice (at 6 and 9 weeks of age) before the initial temperature change, and at 10 days and 4 weeks after the initial temperature change (at 11.5 and 14 weeks of age). Results Except for an increase in plasma corticosterone in the HC group and a decrease in the L group when the temperature change was first introduced, changes in plasma corticosterone were not significant. There were no significant changes in immunoglobulin concentrations. There were, however, significant decreases in the total white cell and lymphocyte counts in the LC group after the temperature was decreased to 28°C, and an increase in these counts after water temperature was returned to 32°C. Clutch of origin had significant effects on body weight and length gains, and there were negative relationships between body weight and corticosterone concentrations and between body weight and immunoglobulin concentrations. Conclusions As haematological changes indicative of stress were not associated with significant changes in serum corticosterone, immunosuppression in young crocodiles may be independent of the hypothalamic-pituitary-adrenal cortical axis.