SPAWNING OF BLACK GHOST KNIFEFISH, Apteronotus albifrons WITH DIFFERENT SEX RATIOS

Black ghost knifefish, Apteronotus albifrons, is a South America-introduced ornamental fish species that has been widely cultivated in Indonesia. Some farmers breed this fish with different sex ratios, but the optimum sex ratio remains unclear. This study aimed to evaluate the spawning behavior and reproductive performance of black ghost knifefish with different sex ratios. The treatments in this study were arranged in a completely randomized design consisting of different sex ratios between males and females, namely: A (one male : three females), B (two males : three females), and C (three males : three females). Each treatment was done in triplicate. The broodstock were maintained in an aquarium (80 cm x 40 cm x 40 cm) and fed with bloodworm twice a day. The water was changed every day as much as 60% of the total volume. During the experiment, the parameters of spawning behavior, number of fish spawning, number of eggs, fertilization rate, hatching rate, and daily spawning frequencies were observed. The observation was done for seven days. The study results showed that black ghost knifefish spawned at night (11 pm - 2 am). The mating and spawning occurred between one male and one female. Competition between males was observed in the treatments indicated by aggressive movements of a male toward the others, such as sudden approaching, chasing, and driving away the others. Fish in treatment-B spawned consistently from day-1 to day-5. Fish in treatment-A spawned from day-2 to day-4, while fish in treatment-C spawned only on day-7. The reproductive performance parameters showed no significant difference in all treatments except the hatching rate parameter of treatment-B. The study concludes that better reproductive performance of black ghost knifefish, A. albifrons can be achieved with a spawning ratio of two males and three females. Further research on individual and mass spawning methods with the best spawning ratio of the fish is required.

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Reproductive performance of asian catfish (Hemibagrus wyckii Bagridae), a candidate species for aquaculture

F1000Research ◽

10.12688/f1000research.14746.1 ◽

2018 ◽

Vol 7 ◽

pp. 683 ◽

Cited By ~ 2

Author(s):

Netti Aryani ◽

Indra Suharman ◽

Hafrijal Syandri

Keyword(s):

Reproductive Performance ◽

Fertilization Rate ◽

Culture Conditions ◽

Hatching Rate ◽

Male Fish ◽

Egg Weight ◽

Study Results ◽

Candidate Species ◽

Asian Catfish ◽

Egg Diameter

Background: Hemibagrus wyckii Bagridae is one of the most important economic fish species that lives in the rivers and reservoir in Riau Province, Indonesia. The present study aimed to determine the reproductive performance of H.wyckii under culture conditions. Methods: A total of 10 female and 10 male fish were selected, and weight, length, characteristics of egg and sperm, and hatchery performance were measured. Eggs were fertilized using the dry method. Egg weight and egg diameters were measured for 50 eggs per female. Egg size (50 eggs for each fish) was measured using an Olympus microscope (CX40). Then, saline solution was added over the eggs, followed by the addition of pooled sperm from 10 males. Results: Average relative fecundity, egg weight and egg diameter were 2060±512 eggs/kg fish, 29.86±1.21 mg and 2.67±0.26 mm, respectively. The fertilization rate and hatching rate were 60.91±4.68% and 42.91±2.92% respectively. Sperm characteristics such as volume per fish (mL), pH, concentration (per mL), motility (%) and duration of motility (second) were 0.82±0.20, 7.15±0.12, 3.68±0.15, 72.77±1.46 and 47.5±4.84, respectively. Conclusion: The study results and scientific observations regarding reproductive performance suggest that H. wyckii can be considered a new candidate species for aquaculture.

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PERFORMA REPRODUKSI UDANG WINDU, Penaeus monodon TRANSGENIK PASCA INSEMINASI BUATAN MENGGUNAKAN SUMBER SPERMATOFOR YANG BERBEDA

Jurnal Riset Akuakultur ◽

10.15578/jra.13.1.2018.11-20 ◽

2018 ◽

Vol 13 (1) ◽

pp. 11 ◽

Cited By ~ 1

Author(s):

Samuel Lante ◽

Andi Tenriulo ◽

Andi Parenrengi

Keyword(s):

Reproductive Performance ◽

Penaeus Monodon ◽

Fertilization Rate ◽

Hatching Rate ◽

Air Exposure ◽

Wild Male ◽

Tiger Shrimp ◽

Larval Quality ◽

Significant Difference ◽

Different Sources

Udang windu transgenik merupakan udang hasil rekayasa dengan mengintroduksikan gen antivirus yang diisolasi dari udang windu untuk menghasilkan fenotipe yang lebih baik. Domestikasi udang transgenik telah dilakukan dan berhasil memijah/bertelur, tetapi umumnya telurnya infertil yang disebabkan tidak terjadinya pembuahan di tambak pemeliharaan. Udang betina tidak kawin ditandai tidak membawa spermatofor di telikumnya. Upaya untuk mendapatkan telur fertil udang dengan inseminasi buatan (IB) perlu dilakukan. Tujuan penelitian untuk mengevaluasi performa reproduksi udang betina transgenik dan mutu larva yang dihasilkan pasca IB menggunakan sumber spermatofor yang berbeda. Penelitian ini dirancang dengan tiga perlakuan yaitu: IB menggunakan spermatofor udang windu jantan transgenik (SJT), spermatofor udang windu jantan alam Sulawesi Selatan (SulSel) (SJS) dan spermatofor udang windu jantan alam Aceh (SJA). IB dilakukan pada udang windu betina transgenik setelah dua hari moulting. Hasil penelitian menunjukkan bahwa udang windu betina transgenik pasca IB perlakuan SJT menghasilkan total telur fertil sebanyak 766.949 butir, perlakuan SJS 535.644 butir dan perlakuan SJA 678.016 butir dengan daya tetas telur fertil yaitu: pada SJT, SJS, dan SJA masing-masing adalah 53,5%; 53,7%; dan 55,0%. Uji vitalitas larva dengan perendaman dalam larutan formalin 150-200 mg/L, perendaman air tawar: 5-15 menit, dan pengeringan 3-9 menit menghasilkan sintasan larva udang yang relatif sama pada ketiga perlakuan. Nilai morfologi larva perlakuan SJT, SJA, dan SJS adalah masing-masing 85,0; 84,5; dan 75,0. Dari hasil penelitian ini mengindikasikan bahwa performa reproduksi udang windu betina transgenik dan mutu larva yang dihasilkan pasca IB tidak dipengaruhi oleh sumber spermatofor induk udang windu jantan Penaeus monodon.Transgenic tiger shrimp, Penaeus monodon has been developed in the last decade to equip shrimp with immunity against viral diseases. However, the effort to produce large quantities of specific pathogen resistance (SPR) tiger shrimp seed is hampered by several constraints in the domestication process. The successfulness of domesticated broodstock in producing larvae is very low due to low fertilization rate. An artificial insemination (AI) offers a solution to increase fertilization rate in crustacean. This study was aimed to evaluate the reproductive performance of female transgenic tiger shrimp broodstock and their larval quality after artificially inseminated with males from different sources. The spermatophores of male from different sources i.e. transgenic male spermatophore (SJT), wild male from South Sulawesi (SJS), and wild male from Aceh (SJA) were collected through electric shock and inseminated to female transgenic broodstock two days after moulting. The results showed that the total numbers of fertile eggs produced from SJT, SJS, and SJA treatment were 766,949 pcs; 535,644 pcs; and 678,016 pcs, respectively and not significantly different (P>0.05). Similar to the number of fertile eggs, the hatching rate of eggs of SJT (53.5%), SJS (53.7%), and SJA (55.0%) also did not indicate any significant differences (P>0.05). On the larval vitality test by soaking the larvae in formalin and freshwater as well as by air exposure at different duration showed no significant difference on the survival rate (P>0.05) as indicated by score value at each treatment of 85.0, 84.5, and 75.0 for SJT, SJS, and SJA, respectively. In conclusion, the reproductive performance of female transgenic tiger shrimp and their larval quality were not affected by the different sources of spermatophores inseminated artificially during the spawning cycle.

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REPRODUCTIVE PERFORMANCE OF DOMESTICATED BROODSTOCK OF SILVER PERCH, Bidyanus bidyanus (MITCHELL 1838) AND THE RELATIONSHIP BETWEEN OIL GLOBULE FRAGMENTATION AND EGG QUALITY

Indonesian Aquaculture Journal ◽

10.15578/iaj.12.2.2017.43-51 ◽

2017 ◽

Vol 12 (2) ◽

pp. 43 ◽

Cited By ~ 1

Author(s):

Sulaeman Sulaeman ◽

Ravi Fotedar

Keyword(s):

Survival Rate ◽

Reproductive Performance ◽

Egg Quality ◽

Fertilization Rate ◽

Hatching Rate ◽

High Fecundity ◽

Fertilisation Rate ◽

Significant Difference ◽

The Relationship

The experiments investigated the reproductive performance of the domesticated broodstock of the silver perch and the relationship between various degrees of oil globule fragmentation and egg quality. Six years old of second generation broodstock (n=3) were evaluated based on the fecundity, fertilisation rate, hatching rate, the degree of oil fragmentation of egg, and the quality of embryos and larvae produced. The fragmentation were grouped into three categories: un-fragmented (cat-1), moderately fragmented (cat-2), and highly fragmented (cat-3). The results showed that the broodstock had a relatively high fecundity (132,400 ± 7,22), fertilization rate (94.27 ± 1.28%), and hatching rates (87.94 ± 1.23%). The survival rate of larvae at 12 days post hatching (dph) in cat-1 (71.3 ± 0.9%) was higher than cat-2 (66.7 ± 0.9%) whereas cat-2 was higher than cat-3 (61.3 ± 0.3%). The eggs was dominated by cat-1 (78.11 ± 2.44%) which was significantly higher than cat-2 (21.26 ± 2.45%) and cat-3 ones (0.40 ± 0.21%). The survival rate of embryo at 20 hours post spawning (hps) and hatching rate of cat-1 (95.33 ± 0.00% and 93.33 ± 0.00%) and cat-2 (90.00 ± 0.00% and 85.00 ± 0.00%) were significantly higher than cat-3 (72.33 ± 1.76% and 60.33 ± 0.00%). The total length (TL) of the larvae of cat-1 and cat-2 (8.44 ± 0.21 mm and 8.35 ± 0.23 mm respectively) were significantly higher than larvae of cat-3 (7.09 ± 0.14 mm). No significant difference was found in the larval deformities among any categories. In conclusion, the reproductive performance of six year-old broodstock silver perch showing acceptable performance and egg categorisation based on oil globule fragmentation can be used as a useful tool to indicate eggs quality of silver perch.

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Comparative Test Of Ovaprim, Spawnprim, And Hcg In The Process Of Spawning Of Pangasianodon Hypopthalmus, Sauvage 1987.

Jurnal Perikanan dan Kelautan ◽

10.31258/jpk.26.1.17-25 ◽

2021 ◽

Vol 26 (1) ◽

pp. 17

Author(s):

Vinka Leonita ◽

Deny Sapto Chondro Utomo ◽

Hilma Putri Fidyandini

Keyword(s):

Reproductive Performance ◽

Design Method ◽

Economic Value ◽

Fertilization Rate ◽

Comparative Test ◽

Hatching Rate ◽

Hormonal Stimulation ◽

Pangasianodon Hypophthalmus ◽

Significant Difference ◽

Production Target

Pangasianodon hypophthalmus is a type of freshwater fish that has potential and has economic value. Its production target which increases every year causes farmers to spawn with the help of hormonal stimulation. The aimed of this research was to test and find out the results of the use of three different hormones namely Ovaprim, Spawnprim, and HCG in P. hypopthalmus spawning. This research was conducted in January 2020 at the Trimurjo Fish Seed Center, Central Lampung. This research used a randomized complete design method with the 3 treatments, P1 (Ovaprim 0,5 ml / kg), P2 (Spawnprim 0,5 ml / kg), P3 (HCG 500 IU / kg) and 3 replications. The results of this research indicate a significant difference (p <0,05) in the relative fecundity parameters, fertilization rate, and hatching rate, but not significantly different in the parameters of latensi periode and diameter of eggs. In P1, Ovaprim hormone injections provide better reproductive performance compared to Spawnprim and HCG injections.

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Reproductive performance of asian catfish ( Hemibagrus wyckii Bleeker, 1858), a candidate species for aquaculture

F1000Research ◽

10.12688/f1000research.14746.2 ◽

2018 ◽

Vol 7 ◽

pp. 683 ◽

Cited By ~ 2

Author(s):

Netti Aryani ◽

Indra Suharman ◽

Hafrijal Syandri

Keyword(s):

Reproductive Performance ◽

Fertilization Rate ◽

Culture Conditions ◽

Hatching Rate ◽

Male Fish ◽

Egg Weight ◽

Study Results ◽

Candidate Species ◽

Asian Catfish ◽

Egg Diameter

Background: Hemibagrus wyckii Bagridae is one of the important economic fish species that lives in the rivers and reservoir in Riau Province, Indonesia. The present study aimed to determine the reproductive performance of H.wyckii under culture conditions. Method s: A total of 10 female and 10 male fish were selected, and weight, length, characteristics of egg and sperm, and hatchery performance were measured. Eggs were fertilized using the dry method. Egg weight and egg diameters were measured for 50 eggs per female. Egg size (50 eggs for each fish) was measured using Labo microscope model L-711 using software camera 3. Then, saline solution was added over the eggs, followed by the addition of pooled sperm from 10 males. Results: Average relative fecundity, egg weight and egg diameter were 2060±512 eggs/kg fish, 29.86±1.21 mg and 2.67±0.26 mm, respectively. The fertilization rate and hatching rate were 60.91±4.68% and 42.91±2.92% respectively. Sperm characteristics such as volume per fish (mL), pH, concentration (per mL), motility (%) and duration of motility (second) were 0.82±0.20, 7.15±0.12, 3.68±0.15, 72.77±1.46 and 47.5±4.84, respectively. Conclusion: The study results and scientific observations regarding reproductive performance suggest that H. wyckii can be considered a new candidate species for aquaculture.

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BIOLOGI REPRODUKSI DAN TINGKAT KEBERHASILAN PEMIJAHAN IKAN BAUNG Hemibagrus nemurus (Valenciennes, 1840) POPULASI CIRATA DENGAN INKUBASI SUHU BERBEDA

Jurnal Riset Akuakultur ◽

10.15578/jra.13.2.2018.131-136 ◽

2018 ◽

Vol 13 (2) ◽

pp. 131 ◽

Cited By ~ 1

Author(s):

Deni Radona ◽

Jojo Subagja ◽

Vitas Atmadi Prakoso ◽

Irin Iriana Kusmini ◽

Anang Hari Kristanto

Keyword(s):

Reproductive Biology ◽

Incubation Temperature ◽

Gonadosomatic Index ◽

Fertilization Rate ◽

Maturity Stage ◽

Hatching Rate ◽

Water Heater ◽

Randomized Design ◽

Significant Difference ◽

C 30

Ikan baung merupakan salah satu komoditas populer di Indonesia. Dalam pengembangan budidayanya masih diperlukan input teknologi terutama pada proses pembenihan. Penelitian ini bertujuan untuk mengevaluasi karakter biologi reproduksi dan keberhasilannya dalam proses pemijahan pada ikan baung populasi Cirata yang diinkubasi pada suhu 23°C-24°C, 25°C-26°C, 27°C-28°C, dan 29°C-30°C. Inkubasi induk dilakukan pada styrofoam berukuran 45 cm x 35 cm x 25 cm dengan ketebalan 3 cm. Setiap styrofoam diisi satu ekor induk yang matang gonad. Seleksi tingkat kematangan gonad dilakukan secara kanulasi dan induksi hormon menggunakan LHRH analog (0,6 mL/kg). Penyuntikan dilakukan dua kali dengan selang waktu enam jam. Styrofoam diisi air dengan ketinggian 20 cm, dilengkapi tutup pada bagian atas, water heater, dan sistem aerasi. Inkubasi suhu dilakukan secara eksperimental menggunakan rancangan acak lengkap dengan empat perlakuan suhu dan masing-masing perlakuan diulang sebanyak tiga kali. Hasil penelitian menunjukkan suhu optimal inkubasi pada induk yaitu 27°C-28°C dengan waktu laten 8 jam 35 menit, dan derajat ovulasi 100%. Secara statistik inkubasi induk pada suhu 27°C-28°C menunjukkan nilai karakter biologi reproduksi yang berbeda nyata (P<0,05) dibandingkan dengan inkubasi suhu 23°C-24°C dan 25°C-26°C. Nilai biologi reproduksi yang dihasilkan pada perlakuan terbaik tersebut adalah indeks kematangan gonad 8,6 ± 0,5%; fekunditas 23.909 ± 1.473 butir per ekor; derajat pembuahan 85,5 ± 5,5%; derajat penetasan 69,9 ± 5,0%; dan sintasan 72,3 ± 5,8%. Pada inkubasi suhu 27C°-28°C, telur terdistribusi dengan diameter telur rata-rata sebesar 1,5 mm.Asian redtail catfish is one of the most popular fish commodities in Indonesia. However, improvements in its aquaculture technology are still needed, especially in the breeding process. This study was aimed to evaluate the characters of reproductive biology and level of spawning on Asian redtail catfish from Cirata population incubated at different temperature settings of 23°C-24°C, 25°C-26°C, 27°C-28°C, and 29°C-30°C. Broodstock incubation was conducted in styrofoam boxes (sized 45 cm x 35 cm x 25 cm) with a wall thickness of 3 cm. One mature broodstock was placed inside each Styrofoam. Each styrofoam box was previously filled with freshwater of 20 cm deep, equipped with a lid on top, a water heater, and an aeration system. The gonad maturity stage of each broodstock was determined using cannulation, whilst the hormone induction used LHRH hormone analog (0.6 mL/kg). The injection was performed twice within six hours interval. The incubation was arranged in a completely randomized design (CRD) with four temperature treatments with three replicates. The results showed that the optimal incubation temperature for the broodstock was 27°C-28°C with the latent time ovulation of 8 hours 35 minutes and an ovulation rate of 100%. Statistically, the incubation of broodstock at 27°C-28°C showed a significant difference on the reproductive biological character value (P<0.05) compared to temperature ranges at 23°C-24°C and 25°C-26°C. The reproductive biology parameters generated were gonadosomatic index of 8.6 ± 0.5%; fecundity of 23,909 ± 1,473 egg per individual; fertilization rate of 85.5 ± 5.5%; hatching rate of 69.9 ± 5.0%; and survival rate of 72.3 ± 5.8%. At the incubation temperature of 27°C-28°C, the egg was distributed with an average egg diameter of 1.5 mm.

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Reproductive Performance Following Hysteroscopic Surgery for Uterine Septum: Results from a Single Surgeon Data

Journal of Clinical Medicine ◽

10.3390/jcm10010130 ◽

2021 ◽

Vol 10 (1) ◽

pp. 130

Author(s):

Ertan Saridogan ◽

Mona Salman ◽

Lerzan Sinem Direk ◽

Ali Alchami

Keyword(s):

Reproductive Performance ◽

Observational Studies ◽

Patient Characteristics ◽

Reproductive Outcomes ◽

Hysteroscopic Surgery ◽

High Quality Evidence ◽

Study Results ◽

Significant Difference ◽

Uterine Septum

Uterine septum can negatively affect reproductive outcomes in women. Based on evidence from retrospective observational studies, hysteroscopic incision has been considered a solution to improve reproductive performance, however there has been recent controversy on the need for surgery for uterine septum. High quality evidence from prospective studies is still lacking, and until it is available, experts are encouraged to publish their data. We are therefore presenting our data that involves analysis of the patient characteristics, surgical approach and long-term reproductive outcomes of women who received treatment for uterine septum under the care of a single surgeon. This includes all women (99) who underwent hysteroscopic surgery for uterine septum between January 2001 and December 2019. Of those 99 women treated for intrauterine septum who were trying to conceive, 91.4% (64/70) achieved pregnancy, 78.6% (55/70) had live births and 8.6% (6/70) had miscarriages. No statistically significant difference was found in the live birth rates when data was analyzed in subgroups based on age, reason for referral/aetiology and severity of pathology. Our study results support the view that surgical treatment of uterine septa is beneficial in improving reproductive outcomes.

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Effects of cooling on the reproductive performance of gilts

Journal of Applied Sciences and Environmental Management ◽

10.4314/jasem.v20i2.17 ◽

2016 ◽

Vol 20 (2) ◽

pp. 357-361

Author(s):

J.O. Oyedeji ◽

G.O. Imagbenikaro

Keyword(s):

Birth Weight ◽

Litter Size ◽

Reproductive Performance ◽

Feed Intake ◽

Cooling System ◽

Large White ◽

Feed Cost ◽

Randomized Design ◽

Significant Difference ◽

Level Of Significance

The study examined the effect of cooling on the reproductive performance of gilts using 27 Large White Experimental Gilts on a Completely Randomized Design (CRD) with 3 systems of cooling, namely Wallow Cooling (WC), Sprinkler Cooling (SC) and Zero Cooling (ZC). Gilts were weighed at the commencement of the experiment and thereafter fed ad libitum from service to farrowing. Feed intake till farrow, feed cost, gilt weight at farrow, date of farrow, litter size and weight were recorded. The feed/piglet weight, feed intake/litter, feed cost/litter and birth weight/piglet were derived. The results showed that feed intake per litter and feed per piglet weight were highest for gilts placed on WC(P< 0.05), followed by SC and least for sow placed on ZC; gilt weight before farrow was highest for sow placed on SC (69.78±0.92), followed by ZC (69.33±0.94) and least for gilts placed on WC (67.33±0.87); litter sizes of gilts placed under the WC and SC systems were similar (5.6±0.41) while that under the ZC system was comparatively smaller (5.4±0.40);while the date of farrow was lowest in the ZC system (113.8±0.32) followed by SC (114.0±0.33) and highest under the WC (114.1±0.33). However, the feed intake per litter, feed per piglet weight, litter sizes of gilts, birth weight per piglet of gilts and the average date of farrow among gilts placed on WC, SC and ZC were not statistically different at 5% level of significance. Though, there is no significant difference in the performance among gilts placed on WC, SC and ZC, temperature regulation through provision of efficient cooling system in piggery would help to increase litter size, improve feed intake per litter and reduce the average cost of feeding gilt per day in maximizing reproductive performances in pigs.Keywords: Cooling, gilts, service, farrow, piggery, litter size, piglet and birth weight

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Reproductive Performances and Egg Qualities in African Catfish (Clarias gariepinus) Broodstocks Supplemented with Curcumin and Thyroxine Hormone

Omni-Akuatika ◽

10.20884/1.oa.2020.16.1.696 ◽

2020 ◽

Vol 16 (1) ◽

pp. 32

Author(s):

Livana Dethris Rawung ◽

Damiana Rita Ekastuti ◽

Muhammad Zairin Junior ◽

Min Rahminiwati ◽

Ade Sunarma ◽

...

Keyword(s):

Reproductive Performance ◽

Egg Quality ◽

Gonadosomatic Index ◽

Clarias Gariepinus ◽

Density Lipoprotein ◽

Cholesterol Concentration ◽

Hepatosomatic Index ◽

African Catfish ◽

Hatching Rate ◽

Significant Difference

An experiment was designed to study the effects of curcumin and thyroxine hormone supplementation in the diet to improve the reproductive performance of catfish broodstock by improving egg quality that eventually increases the production of seedlings. Catfish used in this experiment were supplemented with curcumin and thyroxine hormone through their feeds for 12 weeks. The results showed that there was no significant difference (p > 0.05) in the hepatosomatic index (HSI), gonadosomatic index (GSI), percentage of gonad maturity, total cholesterol concentration in the spawned eggs, high density lipoprotein (HDL) concentration in the spawned eggs, fertilization rate of spawned eggs, and hatching rate of fertilized eggs. However, there were significant differences (p < 0.05) in the concentration of vitellogenin in the spawned eggs, egg diameter of the spawned eggs, and the triglycerides contents of spawned eggs. It was concluded that curcumin and thyroxine supplementations of African catfish increased vitellogenin concentrations and diameters of spawned eggs that have great potential to improve the reproductive performance.

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Effects on reproduction of prolonged grazing of oestrogenic pastures by ewes

Australian Journal of Agricultural Research ◽

10.1071/ar9681059 ◽

1968 ◽

Vol 19 (6) ◽

pp. 1059 ◽

Cited By ~ 12

Author(s):

HE Fels ◽

HG Neil

Keyword(s):

Reproductive Performance ◽

Reproductive Tract ◽

Subterranean Clover ◽

Fertilization Rate ◽

Reproductive Tract Infections ◽

Significant Difference ◽

The Difference ◽

Tract Infections

Six-year-old ewes, the survivors of two experimental groups that had grazed from May to October through the 5 preceding years on mixed pastures containing an oestrogenic variety (Dwalganup) of subterranean clover ("clover" group) and oat crops ("oats" group), were mated 6 months after their last exposure to oestrogenic pasture and allocated for slaughter to observe the fertilization rate of eggs or the numbers of surviving embryos. In late April the clover and oats groups did not differ significantly in the proportion of eggs fertilized (13/15 eggs v. 11/11) but in May there was a highly significant difference (4/12 v. 14/17). The difference between late April and May in the clover group was significant and was associated with changes in the ratio of oestrous ewes to rams. The ratio of live embryos to eggs shed was much higher in the oats than in the clover group (56173 v. 8/39). After estimating how many of these eggs had been fertilized it was concluded that more fertilized eggs developed successfully in the oats than in the clover group (c. 56/65 v. 8/17). The data suggested that more "clover" embryos died during days 13–19 of pregnancy. Significantly more clover group ewes had obvious reproductive tract infections. These ewes did not show oestrus regularly though they may have ovulated more or less regularly. Other clover group ewes showed oestrus as regularly as oats group ewes. Clover group ewes had many more macroscopic endometrial cysts in their uteri and cervices, but within groups, numbers of cysts were not significantly associated with previous or current reproductive performance.

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