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21.
通过研究中华鼢鼠生物学特性,其食性食量125g/d,每个洞内食物存放平均750g;解剖观察,怀孕胚胎2~4个,平均3.38个,雌雄比为53.164∶6.84。 相似文献
22.
Marianne Frantzen Arne M. Arnesen Brge Damsgrd Helge Tveiten Helge K. Johnsen 《Aquaculture (Amsterdam, Netherlands)》2004,240(1-4):561-574
Four groups of Arctic charr (age 3+), previously exposed to natural photoperiod, were subjected to different photoperiod regimes from February 20: Simulated natural photoperiod (SNP; Tromsø 70°N), continuous light (LD 24:0) followed by short day (LD 6:18) from either May 1 (LFeb–May) or June 25 (LFeb–June), or continuous light (LD 24:0) throughout the experiment (LContinuous). In females, peak levels of estradiol-17β and testosterone were 6 and 10, 6 and 7, and 3 and 5 weeks advanced, in LFeb–May, LFeb–June and LContinuous, respectively, whereas in males plasma levels of 11-ketotestosterone peaked 8 weeks earlier in LFeb–May and LFeb–June than in SNP and LContinuous. Median ovulation time in LFeb–May and LFeb–June was advanced by 10 weeks compared to SNP and LContinuous, and median spermiation time (first observation of running milt in each individual) in LFeb–May, LFeb–June and LContinuous was advanced by 10, 7 and 5 weeks, compared to SNP. A switch from long to short day early in the reproductive cycle (LFeb–May and LFeb–June) apparently resulted in stronger synchronization of both ovulation and spermiation. Ovulation in LFeb–May and LFeb–June occurred over 3 weeks (LFeb–May) and 8 weeks (LFeb–June), as compared to 10 weeks in the SNP group, whereas all males (except one individual) began spermiating over a period of 3 weeks (LFeb–June), or less (LFeb–May), as compared to 7 weeks in the SNP group. Lack of a short day stimulus (LContinuous), on the other hand, resulted in larger variation in the timing of final maturation, with ovulation and spermiation being spread over 15 weeks. Low egg survival in LFeb–May (17% versus 60% and 97% for LContinuous and SNP) indicate that a long day signal of 10 weeks early in the reproductive cycle may be too short to ensure good egg and sperm quality. Photoperiod manipulation did not affect the proportion of maturing fish. 相似文献
23.
A study of the reproductive cycle of the baby clam, Marcia opima (Gmelin) was conducted at two sites along the southeast (Tuticorin Bay) and southwest (Ashtamudi estuary) coast of India from December 1998 to January 2000. Histological evidence showed that baby clam from both the sites showed two spawning seasons. First spawning season was recorded from May to July in the southeast coast. In the southwest coast, the first spawning season was observed through March to May. A second spawning season from September to December was recorded in both the coasts. In the southeast coast, minimum and maximum condition indices were obtained in January 2000 and April 1999 respectively and decreased from May to June and November to January, signifying the two spawning periods. Most of the animals were either in spent or indeterminate gonadal stage from May to August and November to January indicating the active spawning during that months in the southeast coast. 相似文献
24.
Jonas Malmsten Lennart S?derquist Carl-Gustaf Thulin Dolores Gavier Widén Lisa Yon Michael R Hutchings Anne-Marie Dalin 《Acta veterinaria Scandinavica》2014,56(1):23
Background
The moose (Alces alces) is an intensively managed keystone species in Fennoscandia. Several aspects of reproduction in moose have not been fully elucidated, including puberty, timing of mating and oestrus, and the length of the oestrus period. These aspects are relevant for an adaptive management of moose with respect to harvest, population size, demography and environmental conditions. Therefore, an investigation of female moose reproduction was conducted during the moose-hunting period in southern Sweden from 2008 to 2011.Results
A total of 250 reproductive organs and information on carcass weight and age was collected from four different hunting areas (provinces of Öland, Småland, Södermanland, and Västergötland) in southern Sweden. The results showed that puberty in female moose varied with carcass weight, age, and time of season. The period for oestrous/mating lasted from about mid September to the beginning of November.Conclusions
The oestrus period (predominantly for heifers) is longer than previously reported and was not finished when the hunting period started. Sampling the uterine cervix to detect spermatozoa was a useful method to determine if mating had occurred. To avoid hunting of moose during oestrus, we suggest that the hunting period should be postponed by at least 14 days in southern Sweden. 相似文献25.
Noritaka ADACHI Daisuke YAMAGUCHI Akiyuki WATANABE Narumi MIURA Seiji SUNAGA Hitoshi OISHI Michiko HASHIMOTO Takatsugu OISHI Masaki IWAMOTO Hirofumi HANADA Masanori KUBO Akira ONISHI 《The Journal of reproduction and development》2014,60(2):100-105
The objective of this study was to examine the health and meat production of cloned sows
and their progenies in order to demonstrate the application of somatic cell cloning to the
pig industry. This study compared the growth, reproductive performance, carcass
characteristics and meat quality of Landrace cloned sows, F1 progenies and F2 progenies.
We measured their body weight, growth rate and feed conversion and performed a
pathological analysis of their anatomy to detect abnormalities. Three of the five cloned
pigs were used for a growth test. Cloned pigs grew normally and had characteristics
similar to those of the control purebred Landrace pigs. Two cloned gilts were bred with a
Landrace boar and used for a progeny test. F1 progenies had characteristics similar to
those of the controls. Two of the F1 progeny gilts were bred with a Duroc or Large White
boar and used for the progeny test. F2 progenies grew normally. There were no biological
differences in growth, carcass characteristics and amino acid composition among cloned
sows, F1 progenies, F2 progenies and conventional pigs. The cloned sows and F1 progenies
showed normal reproductive performance. No specific abnormalities were observed by
pathological analysis, with the exception of periarteritis in the F1 progenies. All pigs
had a normal karyotype. These results demonstrate that cloned female pigs and their
progenies have similar growth, reproductive performance and carcass quality
characteristics and that somatic cell cloning could be a useful technique for conserving
superior pig breeds in conventional meat production. 相似文献
26.
27.
The life cycle of cuttlefish fed ad libitum exclusively on live grass shrimp (Palaemonetes varians) was studied during 5 consecutive generations. Different culture temperatures promoted different (P < 0.05) exponential growth for each life cycle, being summer generations shorter than those of winter. Higher temperatures promoted higher IGR’s and mortality, while lower temperatures promoted increased life span, reproduction stages, total fecundity and total egg biomass. Increased generations also seemed to increase fertility. A “hybrid” generation promoted the best results in terms of hatchling weight, individual fecundity and fertility. Mean egg weight was related to female size and embryonic development took longer at lower temperatures. Brood stock sex ratios seemed to be temperature related. All of these culture aspects were also compared between themselves in order to establish future brood stock methodologies. Grass shrimp proved to be a good diet for the culture of cuttlefish throughout the life cycle. The use of only one species reduces costs and labor associated to cuttlefish culture. 相似文献
28.
Otomar Linhart Steve D. Mims Boris Gomelsky Ana E. Hiott William L. Shelton Jacky Cosson Marek Rodina David Gela Jan Bastl 《Aquaculture International》2003,11(4):357-368
Changes in ionic composition as Na+,K+, Ca2+ and Mg2+, osmolality inseminal fluid, percentage of motile spermatozoaand velocity were investigated in response toCPP and different dosage of LHRHa. The lowestvelocity of sperm was observed after use CPPtreatment. The velocity of spermatozoa,significant main effect of the treatment(P < 0.0001) and the time of sperm collection(P < 0.0104) were evaluated. The osmolality ofseminal fluid was different betweenexperimental groups of LHRHa (48.0–62.7mOsmol.kg–1) and CPP (33.0–46.3mOsmol.kg–1) treatments. The osmolalitywas significantly higher on the first day andone-half, then declined on day three, rangingfrom 33.0 to 62.7 mOsmol.kg–1. Analysisof variance showed significant main effects ofthe treatment (P < 0.0001) and the time ofsperm collection (P < 0.0002) on the osmolalityof seminal fluid. The level of Na+ andK+ ion was different between experimentalgroups of LHRHa and CPP treatment. The highestconcentration of 11.11 mmol.l–1 wasobserved at Na+ ion. Then theconcentrations declined on the level 1.56, 0.52and 0.36 mmol.l–1 for K+, Ca2+and Mg2+ ions, respectively. There werehighly positive correlations between osmolalityof seminal fluid and dosage of LHRHa treatment(r = 0.84), velocity of spermatozoa andosmolality of seminal fluid (r = 0.57) andosmolality of seminal fluid and Na+concentration at seminal fluid (r = 0.70).Injection with LHRHa increased quality of spermas velocity of sperm, level of Na+,K+ and osmolality at seminal fluidcompared to CPP treatments. 相似文献
29.
暗纹东方鱼屯俗称河豚,属江海洄游性鱼类。生殖季节,雌、雄个体副性征差异不明显,不能采用常规鉴别方法进行性别鉴定。作者根据体征、体态特征,采用综合指标判别法对1995年3月15日至5月30日在江苏仪征—泰州60km江段渔获的1038尾暗纹东方鱼屯进行了雌、雄性别判定,正确率达95.4%。该方法操作简单,不伤鱼体,仅凭眼观即可判定自由游动状河鱼屯的雌、雄。文中有关利用行为差异来判定鱼类雌、雄的方法,国内外尚未见诸报道。该项工作为鉴别鱼类性别提供了一种新方法,在鱼类人工繁殖和规模化生产中具有一定应用价值 相似文献
30.
Jianjun Zang Jingshu Chen Ji Tian Aina Wang Hong Liu Shengdi Hu Xiangrong Che Yongxi Ma Junjun Wang Chunlin Wang Guanghua Du Xi Ma 《畜牧与生物技术杂志(英文版)》2014,5(1):39
The objective of this study was to evaluate the effects of supplemental magnesium (Mg) on the performance of gilts and parity 3 sows and their piglets. Fifty-six gilts (Trial 1) and 56 sows (Trial 2) were assigned to one of 4 treatments according to their mating weight, respectively. The treatments comprised corn-soybean meal based gestation and lactation diets (0.21% magnesium) supplemented with 0, 0.015, 0.03, or 0.045% Mg from mating until weaning. The results showed that magnesium supplementation significantly (P < 0.05) reduced the weaning to estrus interval in both gilts and sows. There were significant effects (P < 0.05) of supplemental magnesium on the total number of piglets born, born alive and weaned in sows. In late gestation and lactation, the digestibility of crude fiber (quadratic effects, P < 0.05), and crude protein (P < 0.05), were significantly influenced by magnesium in gilts and sows, respectively. There were differences among the 4 groups in terms of the apparent digestibility of dry matter and crude fiber in sows (P < 0.05) during both early and late gestation. The apparent digestibility of gross energy was increased for sows in late gestation (P < 0.05), and lactation (quadratic effects, P < 0.05). At farrowing and weaning, serum prolactin levels and alkaline phosphate activities linearly increased in sows as the Mg supplementation increased (P < 0.05). Serum Mg of sows at farrowing and serum urea nitrogen of sows at weaning was significantly influenced by Mg supplementation (P < 0.05). The Mg concentration in sow colostrum and the serum of their piglets were increased by supplemental magnesium (P < 0.05). In addition, growth hormone levels were linearly elevated (P < 0.05) in the serum of piglets suckling sows. Our data demonstrated that supplemental magnesium has the potential to improve the reproduction performance of sows, and the suitable supplemental dose ranged from 0.015% to 0.03%. 相似文献