Some features of experimental researches in sheep breeding: to help of young scientists

Organizing and conducting scientific and farm experiment is one of the most important components of any scientific and research work. The features of the modern period of animal husbandry development, the state of the feed base in all categories of farms, the availability of qualified specialists, the level and culture of conducting selection and technological techniques, create the main conditions for reliable performance of experimental researches. In sheep breeding the success of research work on the selection plan depends to a large extent on careful individual accounting of the results of insemination and lambing of ewes. Currently, in different categories of sheep farms crossbreeding is used as one of the methods for faster improvement and increasing the productivity of animals. At the same time, it is not always clear from the materials of many researches how the experimental groups of breeding stock were formed, what rules of selection were observed during artificial insemination, how accounting was carried out during insemination and lambing of ewes, what justifies the calculation of some indicators of economic effectiveness of the research without taking into account important economically useful features. The recommendations on how to eliminate possible errors when conducting research and production experiments by young scientists have been provided in the article. In particular, the main principles of forming experimental groups of sheep by age, productivity and origin have been shown. The necessity of housing all sex and age groups of experimental animals with complete feeding has been noted. The most important condition is the same number of ewes inseminated every day with the semen of each mating stud ram. It has been recommended to use vasectomy teaser rams for the authenticity of the origin of the obtained off spring. Special attention has been paid to the need to take into account all valuable economic useful features studied in the course of scientific and production experiments to calculate some indicators of economic effectiveness when rearing off spring of different origin.

Comparative study between the excision-ligation and autoligation of vas deferens technique for teaser rams preparation

Aim: The present study was designed to demonstrate the autoligation (AL) of vas deferens and the excision-ligation (EL) technique to generate vasectomized rams to reduce the complications, operative time, and price of the vasectomy techniques. Materials and Methods: A total of 12 healthy and mature Iraqi Awassi rams were used, which divided into two groups, six rams for each one. The former group was performed the EL technique while the latter group, the AL of vas deferens technique was used. Results: The results of the present study found that both techniques were same with the reproductive efficient examinations that mean the two techniques had same ability to close the male genital passage for teaser rams preparation. However, the methods were different with the histopathological changes, operation time, prices, and complications, which were minor in the AL of vas deferens compared with the EL technique. Conclusion: The AL technique of vas deferens to prepare teaser animal is recommended over the EL technique due to different aspects such as cost, fewer complications, and active teaser for a long period are the main aspects of AL technique.

Fertility Rates of Ewes Treated with Medroxyprogesterone and Injected with Equine Chorionic Gonadotropin plus Human Chorionic Gonadotropin in Anoestrous Season

The aim of the present paper was to investigate the efficiency of the equine chorionic gonadotropin (eCG) plus human chorionic gonadotropin (hCG) associated with medroxyprogesterone acetate (MAP) to estrous ewes synchronization. Ninety Texel ewes were investigated during seasonal anoestrous. The ewes received intravaginal sponges containing MAP (60 mg) for nine days. At the time of sponges' withdrawal, the ewes were divided into three groups (G): (1) receiving 2 mL of saline i.m. (n=30), (2) receiving eCG 400 IU i.m. (n=30), and (3) receiving eCG 400 IU plus hCG 200 IU i.m. (n=30). Twelve h after sponges' removal, teaser rams were used to estrus check and remained with the ewes for 96 h. The artificial insemination was made with fresh semen 10 h after estrus detection. The effect of the treatment was not significant for the estrous rates among the groups: 73%, 90%, and 86%, respectively. The main effect was observed in the pregnancy and lambing rates among the groups: 70%, 86%, 56%, and 80%, 120%, 56%, respectively. Based on these results from our study, the use of the MAP—eCG is the best choice to improve the fertility rate on ewes.

Comparative study between vasectomy and epididymectomy for preparation of teaser Ram

Teaser rams were used for discovering estrus in ewes because this techniqueis very important for super ovulation,embryo transfer and transgenic animalsprograms.sever techniques were used for preparation of teaser animalsespecially in sheeps so this study was designed to compare between twosurgical methods (vasectomy and epididymectomy).Six Assaf of breed rams,Clinical reproduction system,libido and laboratoryexamination (volume ejaculate,mass and individual motility and spermconcentration). were performed 2 week before experiment for qualificationof the general health of the animals the animals were divided into two equalgroups, Vasectomy in the first group and epididymectomy in theanother.Cases were followed up clinically, laboratory examination andhistological.Results showed that surgery of epididymectomy takes longer time thanvasectomy.Vasectomiesed animals showed sever pain during first tow dayswith simple adhesion in the site of operation, while epididymectomy causedsever adhesion between the testis and skin with odema in the site ofoperation also the pain was sever in addition to, it takes longer time than invasectomy. The seminal fluid examination showed disappear of life spermsimmediately after operation vasectomy or epididymectomy also histologicalchanges were obtained in both types of surgical methods ,which includereduce in the rate of spermatogenisis, thickness of basement membren,whilethese changes were more sever after vasectomy.Results of this study was showed that epididymectomy technique shouldsuperior results than vasectomy for longer time.

Effects of Long and Short-Term Progestagen Treatments Combined with PMSG on Oestrus Synchronization and Fertility in Awassi Ewes during the Breeding Season

Synchronization of oestrus has been used to increase reproductive efficiency in most animals, including ewes. The aim of the present study was to compare the effect of the length of a progestagen treatment (12 d vs. 6 d) on synchronization efficiency (oestrus response, time to onset of oestrus and duration of oestrus) and fertility rate using fluorogestone acetate (FGA) progestagen sponge treatment with pregnant mare serum gonadotropin (PMSG) administration applied at different times of sponge removal. Ewes (n = 68) were divided into two groups; long term (LT, n = 33) and short term (ST, n = 35) groups treated with FGA progestagen sponges. At the end of intravaginal sponge treatment period the animals of each group were divided into the 3 subgroups in relation to time of PMSG (300 IU) treatment. PMSG treatment was applied 24 h before sponge removal, at sponge removal and 24 h after sponge removal for LT1 and ST1, LT2 and ST2, and LT3 and ST3, respectively. Each ewe was inseminated intra-cervically twice with skim cow milk-diluted semen (1000 × 106 motile cells/ml) 40 h and 60 h after sponge removal. Non-return rates (NRR-30) were monitored from 12 day after sponge removal to 30 day with the aid of teaser rams. Onsets of oestrus response and oestrus cessation were significantly different (P < 0.05) between the ST and LT treatment groups. Synchronization of oestrus was tighter in LT than ST group. Except for oestrus cessation, other indicators studied were not different in the ST subgroups. In the ST subgroups the oestrus cessation of the ST1 (88.7 ± 15.4 h) was the shortest and differed from ST3 (120.0 ± 14.2 h) (P < 0.05). No statistical difference was observed among all studied indicators for LT groups according to application time of PMSG (P >). The NRR-30 and lambing rate of the ST and LT after timed AI were 35.7% and 31.0% and 32.1% and 28.6%, respectively (P > 0.05).

Ram-induced reproduction in seasonally anovular Corriedale ewes: MAP doses for oestrous induction, ram percentages and post-mating progestagen supplementation

Exploiting the ‘ram effect’ is an inexpensive alternative for out-of-season breeding in moderately seasonal breeds. For maximum efficacy in Corriedale sheep, oestrous ewes have to be introduced together with the teaser rams. Successful applications depend upon timely manipulation of the animals to induce oestrus in most ewes and to minimize the likelihood of successfully induced non-pregnant ewes returning to anoestrus during the mating period.In the first of two experiments, the effects of two alternative ram: ewe ratios (1:6 or 1:12) and five different doses (0, 15, 30, 45 or 60 mg) of medroxy-progesterone acetate (MAP) applied in intravaginal sponges for 9 days were assessed on seasonally anovular adult Corriedale ewes. Control ewes (0 MAP) did not receive sponges, but were injected with 20 mg progesterone at ram introduction. A second experiment tested the efficacy of post-oestrus intravaginally applied MAP (30 mg; 7-day treatment starting on days 3 to 6 after oestrus) for improving reproductive variables of successfully induced ewes exposed to entire rams.Proportions of ewes ovulating and ovulation rates (assessed through laparoscopy) did not differ significantly (P > 0·05) in ewes treated with various MAP doses (213/220 = 96·8% and 1·26 (s.e. 0·031) respectively) or injected with progesterone (56/58 = 96·6% and 1·21 (s.e. 0·058) respectively). The MAP content of the sponges did not affect (V > 0·05) the proportion of ewes ovulating (269/278), marked by the rams (197/213), returning to oestrus (81/197) or lambing among those not returning to first oestrus (87/119). More ewes were marked in the groups exposed to a higher ram percentage (79·7 to 70·6%; P < 0·001) but no other reproductive variable was affected by the ram: ewe ratio at ram introduction (P > 0·05). In the second experiment, post oestrus progestagen supplementation reduced the proportion of ewes returning to first oestrus from 27% to 16% (P < 0·05) but failed to improve lambing rate or the number of lambs born per ewe lambing. Thus, MAP doses as low as 0·25 of the commercial formulation (60 mg) induced oestrus in seasonally anovulatory Corriedale ewes exposed to rams and oestrous ewes. Increasing the ram: ewe ratio augmented the proportion of marked ewes but did not affect any other reproductive variable. Supplementing MAP after oestrus did not improve reproductive rate in Corriedale ewes induced to ovulate during the seasonal anoestrus.