Reproductive Efficiency In Sheep Research Articles

Effect of oxytocin added into sperm on artificial insemination in sheep

Abstract. The use of additional oxytocin hormones in reproductive methods began in the 1970s in Europe. In recent studies, attempts have been made to achieve more successful pregnancies by adding oxytocin to semen rather than administering oxytocin exogenously to females. In light of this information, this study aimed to understand the effects of adding low-dose oxytocin hormone into ram semen on the pregnancy rate and reproductive efficiency of sheep. Semen was collected from five Chios rams. The ejaculates were pooled and Ovixcell® was used as the diluent. The estrus was synchronized using an intravaginal sponge (Chrono-Gest®) from 122 Chios ewes. After the sponge was left in the vagina for 12 d, a 500 IU PMSG injection was made. In every sheep, intramuscular (IM) injections were inseminated by the intracervical method using an insemination gun 50 h after injection. Pregnancy results were obtained by ultrasound examination without practice. Lambing performance was recorded at delivery; 53 out of 122 Chios ewes were inseminated with oxytocin hormone content, and successful pregnancy was achieved in 90.56 % of them. In the insemination of the remaining 69 sheep, oxytocin was not added, and the rate of successful pregnancy was 76.81 % (p=0.046). The overall success rate based on the insemination results of all the sheep was determined to be 82.77 %. In an examination of the pregnancy rate, one of the indicators of reproductive performance, the difference between the groups is statistically significant (p≤0.05). Higher pregnancies were obtained in insemination with semen fluid containing oxytocin.

The effect of RORA (RAR-Related Orphan Receptor Alpha) receptors on litter size in Akkaraman sheep breed.

In this study, the relationship between RORA 23bp indel genotype and allele frequency with twin pregnancy, fertility, live weight and milk yield in 106 female Akkaraman ewes raised in Elazığ province was investigated. In the study conducted in Elâzığ province, 10ml milk was collected from 106 Akkaraman sheep and DNA was extracted from these milk. In RORA 23bp indel genotype frequency, DD genotype was found more than ID and II genotypes and RORA 23bp indel ın allele frequency, the D allele was found to be higher than the I allele. In both the first and second parity, the twinning rate was found to be lower. In both the first and second parity, the twinning rate was higher in the DD genotype, and it was observed that this genotype promınated mıddle lıvestock weıght and mılk yıeld. According to the results of our study, mutations in the RORA gene, which is a gene affecting reproductive efficiency in sheep, do not have a positive effect on fertility and twinning rate in Akkaraman sheep. To sum, this study provided theoretical references for the comprehensively research of the function of RORA gene and the breeding of Akkaraman Sheep. The 23-bp indel variants can be considered as molecular markers for litter size of sheep for marker-assisted selection breeding.

Evaluación en ovejas de la condición corporal con respecto a su estado fisiológico en el norte de La Pampa

For effective sheep production, males and females in good nutritional status, healthy and functional, are needed. The nutritional status can be known through the body condition score, whose evaluation allows corrections in management and increase the productive and reproductive efficiency of sheep according to their physiological status. The objective of this study was to evaluate the body conditioning sheep in relation to their physiological state trough semi-technical exploration, and on this basis make a diagnosis of reliable productive and reproductive situation. The study was carried out in the northern part of La Pampa province, in 8 mixed farms in spring-summer. A disparity of corporal sate was observed in sheep’s with the same physiological state in a sheep flock which means unfit animals. There is a tendency of the productive cycle to lean towards inefficiency that requires management interventions as to synchronize its stages with an optimal animal’s state and achieve maximum development.

Management strategies, reproductive performance and causes of infertility in sheep flocks in the central region of Saudi Arabia.

The objectives of this study were to identify the management strategies, reproductive characteristics, and causes of the infertility in sheep flocks in the central region of Saudi Arabia. Reproductive data were collected from 43 Awassi flocks containing 12,012 heads and 16 Najdi flocks having 2867 heads. Reproductive tracts of females culled from breeding from these flocks (Awassi, n = 127; Najdi, n = 32) were collected from slaughterhouses to detect the common pathological lesions. The results showed that most flocks contained large number of animals housed mainly in shelters and involved small number of workers. Few managers had high school education and very few farms relied on breeding records, regular veterinary visits, and the use of modern reproductive techniques. Sheep flocks with large number of animals; low-educated and less-experienced managers showed higher stillbirth rate than other flocks (P = 0.02). Sheep housed in shelter demonstrated greater lambing rate than sheep managed between grazing and shelter systems (P = 0.03). Ewes bred seasonally had greater lambing rate than those bred all year (P = 0.03). Non-functioning ovaries, pyometra, and ovarian-bursal adhesion were the common findings in the culled barren ewes. In conclusion, reproductive efficiency of sheep in the central area of Saudi Arabia could be improved by reforming some management approaches, justifying workers/animals ratio, instructing sheep breeders, and controlling genital diseases.

Genome -wide transcriptome profiling in ovaries of small-tail Han sheep during the follicular and luteal phases of the oestrous cycle

Ovarian function, the control of which is predominantly integrated by the hypothalamic-pituitary-ovarian axis, is pivotal for maintaining reproductive efficiency in sheep. To understand the regulatory mechanism of the follicular-luteal phase transition in prolific sheep, the genome-wide expression patterns of microRNAs and genes in ovarian tissue of Small Tail Han sheep were examined during the follicular and luteal phases of the oestrous cycle. Differentially expressed genes (n = 450) were identified and a total of 139 known and 72 novel miRNAs were identified in the two libraries. It is suggested that differential abundance of miR-200a, 200b and 200c may have an important role in the follicular-luteal transition. A miRNA-regulated gene expression network was created for exploring the regulation of the follicular-luteal transition and quantitative real-time PCR verified the reliability of the RNA-seq data.

Interactions between parasitic infections and reproductive efficiency in sheep

This review article summarises the many reports in the literature, confirming that, in sheep, parasitic infections can adversely affect reproductive efficiency; examples, which refer to all parts of the reproductive cycle of sheep, are as follows: trichostrongylosis in ewe-lambs (which can lead to delayed attainment of puberty), myiosis of the prepuce (which can cause impediment of mating), chorioptic mange or trypanosomosis in rams (which can lead to testicular degeneration or azoospermia, respectively), trypanosomosis or sarcoptic mange in pre-conceptual ewes (which can lead to poor conception rates or reduced number of ovulations, respectively), toxoplasmosis or neosporosis in pregnant ewes (which are causes of abortion), trichostrongylosis or trematode infections in lactating ewes (which can cause reduction of milk yield and can be a risk factor for mastitis, respectively), cryptosporidiosis in newborn lambs (which can be a cause of deaths), coccidiosis in growing pre-weaned lambs (which can cause suboptimal growth rate). In other cases, the reproductive status of the animal can influence the parasitic infection; examples are as follows: the increase in faecal parasitic output during the peri-parturient period (as a consequence of the peri-parturient relaxation of immunity), the heavier trichostrongylid infections of twin lambs compared to lambs from single parities (as a consequence of developmental origin issues in twin lambs). All the above examples support the idea of presence of interactions between parasitic infections and reproductive efficiency in sheep.

Histological study of the licorice extract as Phytoestrogens, compared with pregnant mare serum gonadotrophyin hormone (PMSG) in the female Reproductive system of Awassi ewes

This study was carried out at the Iraqi ministry of science & Technology as well as the Vet. Collage- Baghdad. This research aimed to study the effects of macroscopic and histological licorice extract in the genital tract of ewes as well as to study the effect of the extract on reproductive efficiency to be compared with serum hormone PMSG( pregnant horse) used for this purpose. The study used (36) local ewes which are divided into three equal groups (T 1, T 2, T 3) (Licorice extract 300, PMSG 500 and zero respectively), The first group( T1) of ewes was given licorice extract a single dose of 300 mg / kg body weight weekly for a period of ( 6) weeks, The second group (T 2), they were treated with hormone PMSG with a dose of 500 unit by intramuscular injection on the day of the raising of the vaginal sponges. As for the third group (T 3) which was given normal saline only it was used as a control group .The study results that the use of licorice extract as (Phytoestrogens) leads to a lack of awareness of the pathological changes on tissue of the genital tract of treated ewes or reduction of fertility and reproductive efficiency. As the study showed that the fertility rate increased ( 1,5%) in the Group of licorice extract which is similar to the group PMSG compared with control group which had a 1.0 fertility rate and a proportion of 88,8% of fertility. In conclusion, the licorice extract could be used to raise the rates of certain reproductive efficiency in sheep without causing any satisfactory damage in the canal genital ewes or reduction to the reproductive efficiency

Beneficial and detrimental effects of dietary condensed tannins for sustainable sheep and goat production—Progress and challenges

Condensed tannins (CT) have improved liveweight gain, wool production and reproductive efficiency in sheep fed temperate forages and reduced the impact of gastro-intestinal parasitism. However, their value is also linked to environmental issues, such as reducing nitrogen pollution from animals grazing lush pastures with a high nitrogen content and lessening methane emissions from rumen fermentation. When forages are fed as a sole diet, the CT in birdsfoot trefoil ( Lotus corniculatus) have been beneficial for ruminant production, but the CT in sainfoin, ( Onobrychis), sulla ( Hedysarum coronarium) and lotus major ( L. pedunculatus) do not appear to benefit productivity other than by mitigating the impact of parasites. The sainfoin, sulla and lotus major have a high feeding value, but the CT per se offer no benefits for nutrition. In contrast to temperate farming, the CT in browse, typical of warm and hot climates, are nearly always detrimental to ruminants, except for reducing internal parasite numbers. Grasses fed in these regions contain less protein (and usually more fibre) than temperate forages and inclusion of CT from browse further reduces protein availability for absorption by limiting ruminal microbial growth and lowering the fractional absorption of amino acids from the intestine. Intakes of CT from browse, in combination with a medium–poor quality diet, are detrimental to performance. However recent studies have shown inclusion of polyethylene glycol (PEG) in diets for sheep and goats grazing scrub and woodland can markedly improve performance, with as little as 10 g/day. The success of research to improve the performance of animals consuming diets containing CT in both temperate and hot climates will depend on communication between animal scientists and chemists. Researchers must measure the astringency and chemical characteristics of CT (and other secondary metabolites), to better understand the impact of tanniniferous feeds on nutritive value. These measurements will enable findings from unrelated trials to be evaluated and provide opportunities for optimising and mitigating the CT in contrasting ruminant production systems.

The effect of melatonin on the reproductive performance of three sheep breeds in Spain

In order to determine the efficacy of melatonin implants in initiating the lambing season and improving reproductive efficiency in sheep, ewes ( n = 1932) from three breeds (Rasa Aragonesa, Assaf and Merino) received melatonin implants (Group M) every 45 days from the winter solstice (1 January and 15 February—winter; 1 April and 15 May—spring) on 12 commercial farms. The other group of ewes ( n = 1715) served as control (Group C). Fertility (percentage of ewes lambed), litter size (number of lambs born per ewe lambed), and fecundity (number of lambs born per ewe in the group) were calculated. Rasa Aragonesa M ewes produced significantly more lambs than the C ewes on farms 3 and 4, after spring melatonin treatment: April (1.16 versus 0.83 lambs-fecundity; P < 0.01) and May (1.23 versus 0.97 lambs; P < 0.05) lambings, respectively. In the Assaf ewes, melatonin implants significantly improved fecundity on farms 5, 6 (winter): January (0.62 versus 0.42 lambs per ewe for M and C groups; P < 0.01) and February (0.64 versus 0.32 lambs; P < 0.01) lambings, respectively and on farm 8 (spring) for May (0.77 versus 0.54 lambs; P < 0.01). This improvement in fecundity is attributed exclusively to significantly higher fertility during these melatonin implantation periods. Concerning the Merino breed, the melatonin treatment increased fecundity only on farm 10, after winter treatment (February) (0.91 versus 0.61 lambs for M and C groups; P < 0.01). It can be concluded that melatonin could be a useful tool to improve lamb production in the three breeds under study, although its efficacy within each breed seems to vary according to the farm and season.

023. Biotechnology and reproduction in mainstream animal industry - a perspective

This paper considers strategies to improve the reproductive performance of small ruminants in ways that lead to production systems that are ‘clean, green and ethical’. This view arises from feedback from consumers, particularly in attractive export markets, and from a need to refocus on the needs of Australian producers, most of whom operate large, extensive enterprises. These people cannot use ‘high-tech’ systems but need low-cost, low-labour solutions to their problems. First, to control of the timing of reproductive events, they can use the socio-sexual inputs of the ‘male effect’ to induce synchronised ovulation in females that would otherwise be anovulatory (seasonal, lactational, prepubertal). Second, they can use nutritional stimuli for ‘focus feeding’, in which short periods of nutritional supplements are precisely timed and specifically designed for individual events in the reproductive process: gamete production, embryo survival, ‘fetal programming’ and colostrum production. Third, they can use simple behavioural observations to genetically select for temperament – this will maximize offspring survival, product quality and animal welfare. All of these approaches involve non-pharmacological manipulation of the endogenous control systems of the animals and complement the detailed information from ultrasound that is now becoming available.1 The use of such clean, green and ethical tools in the management of our animals can be cost-effective, increase productivity and, at the same time, greatly improve the image of meat and milk industries in society and the marketplace. This does not mean, however, that they will not benefit from the opportunities that evolve from breakthroughs in reproductive technology or gene research. On the contrary, if this ‘high-tech’ research is done within the context of the needs of a ‘clean, green and ethical’ industry, first class science can have very direct and immediate benefits to our livestock industries. (1)Martin GB, Milton JTB, Davidson RH, Banchero Hunzicker GE, Lindsay DR and Blache D. (2004). Natural methods of increasing reproductive efficiency in sheep and goats. Anim. Reprod. Sci. 82–83, 231–246.

Effect of peptidoglycan-polysaccharide complex on reproductive efficiency in sheep.

Spontaneous mastitis or induced infections mimicking mastitis reduce pregnancy rates in ruminants. The effect of immunization with either a mastitis-related pathogen component, peptidoglycan-polysaccharide (PG-PS), or killed Streptococcus pyogenes on pregnancy outcome was investigated. Ewe lambs were immunized with PG-PS (n = 50) or killed bacteria (n = 50) or were not immunized (control, n = 100). Titers of PG-PS immunoglobulin G (IgG) were detected by enzyme-linked immunosorbent assay (ELISA). Ewes were bred by rams at synchronized estrus. All immunized ewes and half of the ewes not immunized were challenged with PG-PS on day 5 after breeding. Pregnancy maintenance was evaluated. Although the proportion of ewes pregnant at day 42 after breeding did not differ among treatments, the probability of pregnancy decreased with total dose of PG-PS (P < 0.05). Immunization of ewe lambs with PG-PS or killed S. pyogenes did not improve pregnancy maintenance. Furthermore, the toxic streptococcal component decreased pregnancy rate in immunized sheep in a dose-dependent manner.

The effect of energy or protein supplementation on embryo survival rate in ewes

Embryo survival rate is a major factor determining litter size and overall reproductive efficiency in sheep. In sheep, as ovulation rate increases the proportion of embryos surviving decreases. There is evidence, from cattle, that feeding a rumen-undegradable protein supplement enhances embryo survival rate. The objective of this experiment was to determine the effect on embryo survival rate in high prolific ewes of feeding an energy or protein supplement.

The effect of energy or protein supplementation on embryo survival rate in ewes

Embryo survival rate is a major factor determining litter size and overall reproductive efficiency in sheep. In sheep, as ovulation rate increases the proportion of embryos surviving decreases. There is evidence, from cattle, that feeding a rumen-undegradable protein supplement enhances embryo survival rate. The objective of this experiment was to determine the effect on embryo survival rate in high prolific ewes of feeding an energy or protein supplement.

Functional infertility in sheep.

Most studies on reproductive efficiency in sheep have concerned the prolificacy of the ewe and the lambing rate of the flock. Some work has been done on reproductive failure but this has seldom separated fertilisation rate from embryonic and fetal loss. Inadequate attention has been given to the level of barrenness in working flocks and to the effect of the ram on conception rate and litter size.

Some aspects of reproductive efficiency in sheep.

Some aspects of reproductive efficiency in sheep.