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1.
We examined the distribution of the orexin‐like peptides in the pituitary and median eminence of the flat‐tailed house gecko (Hemidactylus platyurus) using immunohistochemistry. Orexin‐B‐like, but not orexin‐A‐like, immunoreactivity was detected in the pituitary, specifically in the pars intermedia, and these cells corresponded to alpha‐melanocyte‐stimulating hormone (αMSH)‐producing cells. Orexin‐B and αMSH secreted from pars intermedia may modulate secretion of adenohypophyseal cells in the pars distalis. In the median eminence, orexin‐B‐immunoreactive puncta and fibres were observed, and these structures corresponded to gonadotropin‐releasing hormone (GnRH)‐immunoreactive puncta and fibres. Orexin‐B secreted from GnRH‐containing neurons in the hypothalamus may affect thyrotropin‐releasing hormone‐containing neurons resulting in modulation of αMSH secretion of melanotrophs in the pars intermedia. 相似文献
2.
Molecular characteristics and site specific distribution of the pigment of the silky fowl 总被引：19，自引：0，他引：19
Muroya S Tanabe R Nakajima I Chikuni K 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(4):391-395
Silky fowl, a breed of chicken, is hyperpigmented in its various internal tissues. The pigment was extracted from various tissues of two strains of Silky fowl to determine its molecular structure and internal distribution. Analysis by infrared spectroscopy showed two spectrum patterns of the pigment in Silky fowl; one is from ovary and testis, the other is from periosteum and feather. The difference between the two spectra is possibly due to the sulfur contents of melanin. Especially, the spectra of the pigments from feather and periosteum shared the characteristics of synthesized melanin spectrum in common, which indicates that the melanocytes dispersed in these tissues were functionally the same. According to our quantitative analysis, the tissues examined were classified significantly in the order of the pigment content (p<0.05): periosteum > gonads (ovary or testis) = trachea > or = heart, liver, gizzard, cecum, muscles (Pectoralis and Supracoracoideus) and skin. In addition, the specific regions of embryonic neural crest derived cells, such as cardiac artery and various parts of cephalic tissues, were found to be locally hyperpigmented. These data suggest that hyperpigmentation (fibromelanosis) in Silky fowl chicken occurs in a tissue- and organ-specific manner, which is strongly related to neural crest cell development. It is hypothesized that neural crest cells of the bird, containing melanocyte progenitors, acquire unusual ability to differentiate into melanocytes excessively, and to extend the distribution of their descendant along the destinations of neural crest derivatives. 相似文献
3.
McFarlane D Paradis MR Zimmel D Sykes B Brorsen BW Sanchez A Vainio K 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2011,25(4):872-881
Background: Plasma α‐melanocyte‐stimulating hormone (α‐MSH) and adrenocorticotropin (ACTH) concentrations in horses vary with season, confounding diagnostic testing for pituitary pars intermedia dysfunction (PPID). Hypothesis: The goals of this study were to determine whether seasonal variation in plasma α‐MSH and ACTH concentrations in horses is influenced by geographic location, breed, or PPID. Animals: Healthy light breed horses residing in Florida, Massachusetts, and Finland (n = 12 per group); healthy Morgan horses (n = 13); healthy ponies (n = 9) and horses with PPID (n = 8). Methods: Monthly plasma α‐MSH and ACTH concentrations were measured by radioimmunoassay. Nonlinear regression analysis was used to estimate the time of peak hormone concentrations. Mean hormone concentrations in fall and nonfall months were compared. Results: The fall peak plasma α‐MSH concentration occurred earlier in horses residing at more northern locations. Mean seasonal α‐MSH concentrations were similar in all healthy groups at all locations, but in the fall, plasma ACTH concentrations were higher in horses living in more southern locations. Plasma ACTH but not α‐MSH concentrations were higher in Morgan horses compared with light breed horses from the same location. Hormone concentrations of ponies did not differ from those of horses during either season. Concentrations of both hormones were high in the fall compared with the spring in horses with PPID. Conclusions and Clinical Importance: These findings suggest geographic location of residence and breed may affect the onset, amplitude, or both of the seasonal peak of pars intermedia (PI) hormones and should be considered when performing diagnostic testing for PPID. Horses with PPID maintain seasonal regulation of PI hormone output. 相似文献
4.
De Kalyan Kumar Davendra Saxena Vijay Kumar Naqvi Syed Mohammed Khursheed 《Tropical animal health and production》2019,51(3):723-728
Nutritional scarcity during summer and winter is a major constraint for sheep rearing in the semi-arid tropical region. In this region, a new crossbred sheep has been developed by the crossing of a native sheep breed Malpura with a breed of hot-humid coastal region breed Garole. A study was conducted for 9 weeks to assess the physiological response of crossbred (Garole x Malpura x Malpura, GMM) rams under nutritional scarcity in the semi-arid tropical region. Eighteen adult crossbred rams were randomly allocated into three groups of six animals each. The groups are G1 (control, ad libitum feeding), G2 (20% less than ad libitum feeding), and G3 (30% less than ad libitum feeding). The animals were stall-fed with a diet consisting of 70% roughage (Cenchrus ciliaris hay) and 30% concentrate feed. Body weight gain, average daily gain, and feed intake were significantly (P?<?0.05) lower in G2 and G3 as compared to G1 rams. Water intake was significantly (P?<?0.05) higher in G2 and G3. Physiological responses, blood biochemical and endocrine profile did not differ between the groups. The results indicate that the crossbred rams evolved through the crossing of the hot semi-arid tropical region breed with hot humid coastal region breed are able to maintain their body homeostasis despite nutritional scarcity although their body weight decreased.
相似文献5.
Reasons for performing study: The sensitivity and specificity of basal plasma α‐melanocyte‐stimulating hormone (α‐MSH) and adrenocorticotrophic hormone (ACTH) for the diagnosis of pituitary pars intermedia dysfunction (PPID) has not been evaluated in a population‐based study. Objectives: To evaluate basal plasma α‐MSH and ACTH concentrations for the diagnosis of PPID in a population of horses aged ≥15 years. Methods: Owner‐reported data were obtained using a postal questionnaire distributed to an equestrian group. A subgroup of surveyed owners was visited and veterinary examination performed on horses aged ≥15 years. Blood samples were analysed for plasma α‐MSH and ACTH concentrations. Seasonally adjusted cut‐off values for α‐MSH and ACTH concentrations for the diagnosis of PPID were obtained using Youden index values against a clinical gold standard diagnosis (hirsutism plus 3 or more clinical signs of PPID). Results: α‐melanocyte‐stimulating hormone and ACTH were highly correlated with each other and with clinical and historical indicators of PPID. The increase in both α‐MSH and ACTH with increasing numbers of clinical signs in affected horses supports a spectrum of disease. Both variables were affected by season, with derived cut‐off values being higher in autumn compared with other seasons. Sensitivity and specificity were moderate and good in nonautumn seasons (59 and 93%, respectively) for α‐MSH using a cut‐off of 52.0 pmol/l. Sensitivity and specificity were good in nonautumn seasons (80 and 83%, respectively) for ACTH using a cut‐off of 29.7 pg/ml. For both α‐MSH and ACTH, sensitivity and specificity were close to 100% for samples obtained during the autumn period. Conclusions and potential relevance: Basal plasma α‐MSH and ACTH had moderate‐to‐good sensitivity and specificity for the diagnosis of PPID, which improved substantially during the autumn period, suggesting this may be the ideal time to test. Further studies to develop seasonally adjusted reference intervals for different geographical locations are warranted. 相似文献
6.
动物黑色素细胞及其相关性状形成机制的研究进展 总被引：1，自引：0，他引：1
黑色素细胞是合成黑色素的细胞，由其前体细胞黑色素母细胞分化而来，胚胎期黑色素母细胞的形成有两次，一次是具有黑色素细胞特性的神经嵴细胞沿背外侧迁移而形成，另一次是由沿腹侧迁移的神经嵴细胞亚细胞雪旺氏细胞前体（Schwann cell precursors，SCPs）受到某种信号诱导后形成，这是皮肤中黑色素细胞形成的主要方式。黑色素细胞的形成与动物毛发颜色及其他重要经济性状密切相关，其形成的增多或减少，异位形成或异位侵袭均可能导致相应的疾病，但脊椎动物中具有典型黑色素细胞异位形成特征的乌骨鸡却繁衍至今，而且是重要的食用和药用经济动物。探索黑色素细胞的形成及其对相关性状的影响不但能为动物经济性状育种提供相关理论基础，也可为相关疾病的治疗提供理论依据。作者从黑色素细胞的来源及其形成过程中参与的信号因子来探讨其形成机制，并对黑色素细胞相关性状的形成机制尤其是乌质性状进行综述。 相似文献
7.
E E Gardiner 《British poultry science》1971,12(1):31-39
Three trials were conducted to determine the response of two breeds of chickens (Single Comb White Leghorn—SCWL—and commercial crossbred broiler type) to various dietary energy and phosphorus levels. Dietary energy level, dietary phosphorus level and breed each had a consistent highly significant (P<0.01) effect on body weight at 4 weeks of age. A number of significant (P<0.05) and highly significant (P < 0.01) interactions occurred with body weight. The energy x phosphorus interaction was significant (P < 0.05) in the three trials which supports the conclusion that, in the heavy breed at least, the higher the energy level of the diet, the greater the phosphorus requirements. The phosphorus x breed interaction was highly significant (P <0.01) in the three trials supporting the conclusion that the two breeds differed in their phosphorus requirements. The energy x breed interaction was less consistent being highly significant (P < 0.01) in one trial, significant (P < 0.05) in another, and non‐significant in a third. Dietary energy level, breed, and energy x breed were the most consistent factors influencing food‐to‐gain ratio. Mortality was high (20 per cent) when the broiler‐type chickens were fed low phosphorus, low energy diets and increased with each increase in the energy level of the diet. No treatment effect on mortality was observed with the SGWL. 相似文献
8.
H. IWAMOTO F. KATOH T. GOTOH S. NISHIMURA Y. ONO Y. NISHIO 《British poultry science》1998,39(5):589-595
1. Four Shamo (a Japanese game bird) cocks showing different characteristics in the histochemical properties of M. iliotibialis lateralis (ITL) were crossed with White Rock hens to produce male and female crossbred broilers of the 4 lines (90 d of age). Normal broilers (56 d) were used, for comparison. 2. Histochemical properties of ITL and M. supracoracoideus (SC) were compared among the crossbred lines and normal broilers. Myofibres were divided into Types II R, II I and II W showing high, moderate and low reduced nicotinamide adenine dinucleotide dehydrogenase (NADH-DH) activities, respectively. 3. In the ITL of the crossbred cockerels, the percentage of Type II R and II I fibres decreased and conversely Type II W increased in comparison to those in the Shamo. 4. Sex differences of the histochemical properties were recognised only in the ITL of the crossbred, in which the percentage of Type II R fibres was greater in the male. 5. The different characteristics of the parent Shamo cocks were reproduced only in the different fibre type composition of the ITL muscle in the crossbred cockerels. 6. The histochemical features of fibre type seemed to develop with bird age, particularly subsarcolemmal accumulation of formazan granules (indicating high NADH-DH activity) in Type IIR fibres. 7. Breed, line, sex and age differences in the histochemical properties were demonstrated clearly in ITL but not in SC. 相似文献
9.
Pituitaries from intact luteal phase (INT) and ovariectomized (OVX) cows were collected at slaughter to determine whether differences exist among regions of the bovine adenohypophysis in the concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH) and receptors for luteinizing hormone releasing hormone (LHRH). Each adenohypophysis was divided into three paired regions (anterior, AT; medial, M; posterior, PT) by first making a midsagittal cut followed by two transverse cuts of approximately equal size. Values for all variables were similar between paired regions. Mean LHRH receptor, LH and FSH concentrations were greater in OVX than INT adenohypophyseal regions. Receptor and gonadotropin concentrations differed among all three regions and were greatest in the AT, intermediate in the M and lowest in the PT regions of the adenohypophysis. There were significant correlations between LHRH receptor concentrations and concentrations of LH and FSH among the three adenohypophyseal regions for both INT and OVX cows. Therefore, to accurately characterize LHRH receptors from the bovine adenohypophysis, a midsagittal-half of the gland should be used for analysis. 相似文献
10.
应用微卫星标记对12个中国地方乌骨鸡品种遗传多样性的研究 总被引：9，自引：11，他引：9
利用27个微卫星DNA标记对12个地方乌骨鸡品种进行遗传多样性分析，通过计算等位基因频率、多态信息含量、杂合度、有效等位基因数和遗传距离，评估各品种内遗传变异和各品种间遗传相关，并根据遗传距离对12个鸡品种进行了聚类分析。结果表明，各乌骨鸡群体的遗传多样性较为丰富，并具有较高的选择潜力。平均杂合度最高的是竹乡鸡，为0．670；最低的是江山乌骨鸡，为0．581。27个微卫星标记中4个为中度多态座位，1个低度多态座位，22个为高度多态座位；LEI0234与LEI0192分别检测到了10．3与12．2个等位基因。以标准遗传距离为准，遗传距离最近的为沐川乌骨鸡与略阳鸡，为0．1002，而乌蒙乌骨鸡与略阳鸡最远，为0．2546。通过UPG—MA法聚类后，略阳鸡、沐川乌骨鸡、兴文乌骨鸡、盐津乌骨鸡、竹乡鸡首先聚为1类，江山乌骨鸡、郧阳白羽乌鸡、余干乌骨鸡聚为1类；金湖乌凤鸡、丝绒乌骨鸡和丝毛乌骨鸡聚为第3类；乌蒙乌骨鸡独为一类。 相似文献
11.
Nishimura S Oshima I Ono Y Tabata S Ishibashi A Iwamoto H 《British poultry science》2006,47(4):426-432
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. 相似文献
12.
豫北黄牛及其杂交改良牛的生长发育研究 总被引：2，自引：2，他引：0
通过测定分析了西利本杂交牛、利本F1杂交牛和豫北黄牛的初生－24月龄体尺、体重指标，结果表明，西利本三元杂交牛生产发育快，各月龄体尺、体重显著大于豫北黄,比利本F1也有显著提高。 相似文献
13.
Funk RA Stewart AJ Wooldridge AA Kwessi E Kemppainen RJ Behrend EN Zhong Q Johnson AK 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2011,25(3):579-585
Background: Results of diagnostic tests for equine pituitary pars intermedia dysfunction (PPID), including endogenous ACTH concentration and the overnight dexamethasone suppression test (DST), are affected by season. New and potentially more sensitive diagnostic tests for equine PPID, such as thyrotropin‐releasing hormone (TRH)‐stimulated ACTH response, have been developed, but have had limited evaluation of seasonality. Objective: Our purpose was to evaluate seasonal changes in plasma ACTH and alpha‐melanocyte‐stimulating hormone (α‐MSH) responses to TRH administration. Animals: Nine, healthy, aged horses with normal DST results. Methods: Synthetic TRH (1 mg) was administered IV. Plasma ACTH and α‐MSH concentrations were measured at 0, 5, 10, 15, 20, 25, 30, 45, 60, and 180 minutes. Testing was performed in February, July, August, September, October, and November. Mean TRH‐stimulated ACTH and α‐MSH concentrations were compared across months and time by repeated measures analysis of variance. Significance was set at the P < .05 level. Results: Concentrations of ACTH and α‐MSH significantly increased after TRH administration. Endogenous and TRH‐stimulated ACTH and α‐MSH concentrations were significantly different across months with higher concentrations in the summer and fall compared with February. Conclusions and Clinical Importance: Plasma ACTH and α‐MSH responses to TRH administration experience seasonal variation, with TRH‐stimulated ACTH and α‐MSH concentrations increasing from summer through fall. These results support previous evidence of a seasonal influence on the equine pituitary‐adrenal axis. More research is warranted with a larger number of horses to determine if seasonal reference ranges for TRH stimulation testing need to be defined. 相似文献
14.
Pituitary dwarfism has been described in more than 20 German shepherd dogs. Some cases probably were caused by persistent cysts of Rathke's pouch. This is the first histopathological, immunohistochemical and endocrinological study. A 13-month-old, 7-kg, dwarf purebred German shepherd bitch with alopecia and hyperpigmentation was admitted to the clinic for euthanasia. Retardation of growth was noticed when the dog was about two months old. No littermates had this condition. Two subsequent breedings from the same parents produced normal offspring. The clinical parameters in our dog (hematology, function of liver and kidney) were normal. Grossly, the pituitary gland had small and large multiple cysts, which light microscopy showed to be exclusively within the adenohypophysis. The latter had pressure atrophy, and immunohistochemically showed only remnants of the hormone-producing cells (growth hormone-GH; prolactin-PRL; thyrotropin-TSH; luteinizing hormone-LH; adrenocorticotrophin-ACTH/MSH). The thyroid was relatively small, and histologically showed focally resting follicles without lumen. Endocrinological studies showed a surprisingly high value for serum growth hormone (cGH 4.1 ng/ml; normal range 1.8-3.8 ng/ml as determined by a specific homologous radioimmunoassay) and a pathologically low serum somatomedin (SM 0.132; normal value more than 0.50 unit/ml, determined by 35S incorporation in piglet rib cartilage). Hypothyroidism was verified by a low T4 binding value (T4 0.9 micrograms/100 ml; normal 4.1 +/- 0.9 micrograms/100 ml) and a low thyroid binding index (TBI 0.54; normal 0.61 +/- 0.05). While ACTH was lowered (ACTH less than 10 pg/ml; normal 74-210 pg/ml), cortisol was normal (0.81 micrograms/100 ml; normal 0.5-2.5 micrograms/100 ml). Pituitary dwarfism in the 13-month-old bitch can be ascribed to the persistence of one end of the ductus craniopharyngeus, Rathke's pouch. Pressure atrophy of the adenohypophysis led to the loss of most of the hormone-producing tissue. An increase in growth hormone with lowered somatomedin raises questions. We have no conclusive explanation for this, due to the present lack of knowledge of how growth is regulated. High growth hormone and low somatomedin values are found in Laron's syndrome in infants. The literature indicates that pituitary dwarfism in German shepherd dogs may be a hereditary autosomal recessive trait. 相似文献
15.
16.
选择1日龄健康北方3号公鸡450羽,随机分成6组,每组设3个重复,试验Ⅰ组为对照组,试验II、III、IV、V、Ⅵ组分别添加20、40、60、80、100 mg/kg的优力安肽,在同一鸡舍中用围栏将各组鸡隔开（温度、湿度、光照均满足正常生产需要）,自动饮水,自由采食。分别于14、28、42、56、63日龄称重、采血,并于63日龄每重复取3只鸡进行屠宰。结果表明,日粮中添加60 mg/kg优力安肽的处理组与对照组相比,日增重提高了13.98%,料重比降低了3.43%（P<0.05）;试验鸡血液神经肽Y含量随日粮中优力安肽添加水平的增加而升高;试验鸡的日增重与血液生长激素含量呈强正相关（r=0.712）,与胰岛素样生长因子-Ⅰ呈正相关（r=0.812）;料重比与胰岛素样生长因子-Ⅰ呈强负相关（r=-0.796）。北方3号公鸡日粮中添加60 mg/kg的优力安肽,生产性能和经济效益最佳。 相似文献
17.
甘肃省泾川县三元杂交肉牛生长发育的研究报告 总被引：1，自引：1，他引：0
本研究测定并对比研究了德秦黄、德利黄、德西黄、利西黄、利秦黄等三元杂交牛及二元杂交牛初生 ,3月龄、6月龄、1 2月龄、1 8月龄的生长发育指标 ,结果表明 :三元杂交牛比二次杂交牛体尺、体重均有较大幅度的增长、初步筛选出适宜泾川养殖习惯的较佳杂交组合。在农户饲养条件下 ,三元杂交初生重 38kg,比二元杂交牛提高 1 2 .8%～ 5 6.6% ;1 8月龄母牛体重 377.8kg,提高 1 5 .2 %～94.1 % ;1日龄～ 1 8月龄日增重 5 2 8.2 g,增长 9.2 %～ 68.7% ;管围提高幅度为 2 4 .1 %～ 32 .3% ;臀围为 1 .7%～ 32 .3% ;体高为 2 .9%～ 1 5 3% ,体斜长为 5 .5 %～ 1 3.9% ,胸围为 1 1 .4%～ 2 0 .5 %。尻长为 5 .1 %～ 1 1 .8% ,腰角宽为 0～ 2 1 .4% ,髋宽为 0～ 3%。适宜的杂交组合为德秦黄、德利黄、德西黄。三元杂交牛 6～ 1 2月龄生长发育受阻 ,主要是饲料营养水平低所致 ,建议从 2月龄开始用优质饲草和配和配合饲料 ,1 8月龄体重达到 40 0 kg以上 ,再经 3个月育肥 ,2 1月龄达到体重 5 0 0 kg的出栏标准。 相似文献
18.
Data from a reciprocal recurrent selection (RRS) programme involving a White Leghorn and a New Hampshire flock were analysed to determine whether there were genetic differences in the purebred population that came to expression primarily in the crossbred progeny. The RRS programme had been in use for four years. The White Leghorn flock had previously been the subject of long‐continued and intensive family selection. The New Hampshire flock was less highly selected. Egg number, egg weight and body weight were the primary traits under selection. Each year the programme involved about 10 sires and 80 females of each breed, and about 400 offspring of each type of cross.
The overall economic value of the crossbreds consistently exceeded the mid‐parent mean, the difference increased steadily during the RRS programme. Heritabilities of the various traits were higher when calculated on the basis of crossbred offspring than when calculated on the basis of purebred offspring. For egg production in the White Leghorns there was a fairly low correlation between purebred and crossbred offspring of the same male. For other traits in both breeds the correlation between purebred and crossbred offspring was moderately high. There was a significant interaction between males and breed of females for all traits and breeds, except for egg number in the New Hampshire. These results are consistent with the notion that there were genetic differences between the purebred males (particularly the White Leghorn males) that affected the production characteristics of their crossbred progeny differently than their purebred progeny. 相似文献
19.
南德温肉牛与张掖西杂牛三元杂交效果调查 总被引：1，自引：0，他引：1
为了确定本地肉牛主导品种,在原有利木辛、夏洛莱、皮埃蒙特等肉牛品种的基础上,从2004年开始引进南德温牛(冻精)与当地西杂牛进行三元杂交改良,止2007年2月,已产南杂牛3 345头,育肥出栏1 750头.总结了甘肃张掖牛改区三元杂交牛外貌特征,适应能力和繁殖能力的观察和调查结果,同时对初生、3月龄、6月龄体尺,体重进行了测定并与同龄二元杂交牛进行了比较,结果发现南德温三元杂交牛表现出适应性强、生长发育快等特点.为本市选择肉牛主导品种和肉牛良种繁育体系建设提供了多元化的品种来源及理论依据. 相似文献
20.
J.G. Magaña & J.C. Segura-Correa 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2006,123(1):37-43
The objective of this study was to evaluate the body weights up to 18 months of age of 12 breed groups of Zebu (Z), Brown Swiss (BS) and Charolais heifers (CH), and their crosses under tropical conditions. A total of 1434 data on weaning weights adjusted to 240 days (WW8), average daily gain to 240 days (ADG8) and 1025 body weights adjusted to 550 days (BW18) and average postweaning daily gain (ADG18) of heifers born from 1981 to 1995 were used. Cows and calves remained together from birth to weaning and grazed on Guinea grass (Panicum maximum). Years of birth were grouped in three periods, because of the small numbers of observations per year (1981–85, 1986–90 and 1991–95). Similarly, months of birth were grouped in three seasons: dry (February to May), rainy (June to September) and windy and rainy (October to January). Ages of dams were classified in six groups (≤3, 4, 5, 6, 7 and ≥8 years). Breed groups were animals with 12.5%, 25.0%, 50.0%, 62.5%, 75.0% and 100% BS genes and 25.0%, 50.0%, 75.0% and 100% CH genes and also Z and undefined crossbred animals. Data were analysed using a fixed model that included effects of period, and season of birth, age of dam and breed group of heifer. Analyses of variance showed significant (p < 0.05) effects of period, season and breed group for all traits. However, parity was significant (p < 0.05) only for WW8 and ADG8. Interactions among main factors were not significant (p > 0.05). Z heifers gained the least weight to weaning but were similar to BS at 18 months of age. CH were heavier at 18 months of age than BS heifers, but not at weaning. Body weights at 18 months of age of 1/8 and 1/4 BS crossbred heifers were similar (p > 0.05) and lower than F1 (BS × Z) (p < 0.05); however, the later and higher grades of BS had the highest body weights at 18 months of age and were similar to CH and 1/4 CH × 3/4 Z heifers. Undefined crossbred heifers had better performance than the Z breed group. Environmental factors were important sources of variation for pre‐ and postweaning traits. Under the conditions of this study, crossbred heifers generally performed better than Z heifers up to 18 months of age. 相似文献