Seasonal changes in ovulatory activity, plasma prolactin, and melatonin concentrations, in mouflon (Ovis gmelini musimon) and Manchega (Ovis aries) ewes

Seasonal changes in ovulatory activity, plasma prolactin and melatonin concentrations were monitored in a wild (Mouflon) and a domesticated (Manchega) breed of sheep, both originating and living under similar latitudes (40 degrees N). Mouflons express ovarian cycles significantly later than Manchega ewes (October vs. July, P < 0.001); however, they ended cycling one month later than Manchegas (April vs. March, P < 0.05). While prolactin concentrations were high when Manchega ewes started to cycle, they were at their lowest concentrations when Mouflons started cycling. Overall, mean prolactin concentrations were higher (P < 0.001) in Mouflons than Manchegas throughout most of the year. Within the limits of sampling frequency, the duration of melatonin secretion was similar in both groups during the solstice and equinox periods; however, the amplitude was lower (P < 0.01) in Mouflons than Manchegas during the solstice periods. The significant breed differences in the seasonal hormonal changes may be attributed to a genetic influence in the endocrine responses to the same photoperiodic cues.     

Interspecific transfer of IVM IVF-derived red sheep (Ovis orientalis gmelini ) embryos to domestic sheep (Ovis aries )

Two embryo production methodologies were investigated to generate Red sheep embryos for use in an interspecific embryo transfer program. In Experiment 1, 4 multiparous female Red sheep (Ovis orientalis gmelini ) were implanted with CIDR type G devices for 11 d. Forty-eight hours prior to CIDR removal, a total of 22.5 mg bid of FSH-P was administered over a 3-d period. Laparoscopic embryo collection was performed 5 d post breeding, and embryos were transferred to domestic recipient ewes (Ovis aries and Ovis orientalis musimon ). In Experiment 2, 7 nulliparous female Red sheep were implanted with CIDR devices and injected with 200 IU of PMSG and 25 mg of FSH-P on the 8th day of implant insertion. At 60 to 70 h post PMSG/FSH-P treatment, follicular oocytes were aspirated laparoscopically. The recovered oocytes were matured in M199 (with fetal calf serum, FSH, LH, penicillin and streptomycin) at 39 degrees C in a humidified atmosphere containing 5% CO(2). At 24 h oocytes were fertilized with frozen-thawed semen at a concentration of 1.6 x 10(6) sperm/ml. The ova/embryos were placed in CR2 or BOEC culture medium at 20-22 h post IVF. Following 3 to 4 d in culture, embryos were transferred laparoscopically to the uterine horn of synchronized recipients. In Experiment 1, 4 embryos and 6 UFO were collected from 2 embryo donors, respectively. Two embryos were transferred with the aid of a laparoscope to each of 2 Rambouillet recipients, one of which gave birth to a healthy Red sheep lamb at 158 d of gestation. In Experiment2, a total of 62 oocytes was collected from 7 oocyte donors; 16 developed to the 16- to 32-cell stage and were transferred to 8 recipients. Three of these IVM-IVF embryos were transferred laparoscopically to 2 Mouflon recipients, resulting in no pregnancies. Thirteen IVM-IVF embryos were transferred to 6 Rambouillet recipients. Each of these gave birth to a single healthy Red sheep lamb. Gestation lengths of the 3 IVM-IVF lambs ranged from 152 to 162 d. This research demonstrates that when using compatible species IVM-IVF technology in conjunction with interspecific ET can lead to the production of live offspring and can be used to propagate exotic ovine species.     

Behaviour and seasonal variation in heart rate in domestic sheep,Ovis aries

Three major causes of heart rate variation in undisturbed adult ewes were identified: behaviour, season and individual identity. Heart rate was 8 beats/min lower when the ewe was lying than when she was standing. It was increased by ruminating by 2 beats/min above the value for idling, and by a further 6 beats/min when the ewe changed to grazing. It seems that the increases in heart rate when the ewe was standing were simply added to those associated with ruminating or grazing. Heart rate declined slightly during bouts of unchanged behaviour. It varied seasonally from a minimum in December to a maximum some 50% (46 beats/min) higher in June. This variation was closely linked with daylength, basal metabolic rate, food availability, food consumption and the reproductive cycle, although it also occurred in non-breeding animals. Changes in heart rate associated with daylength may be the secondary result of the effects of daylength on metabolic rate. After taking all these effects into account, there remained variation between five ewes of 16 beats/min.     

Interspecific embryo transfer from mouflon (Ovis gmelini musimon) to domestic Corriedale sheep in Argentina

An interspecific embryo transfer program was conducted for genetic improvement and increasing the number of offspring from a flock of mouflon sheep in Argentina. The female donor mouflons were divided into three groups, G1 (n=5), G2 (n=4) and G3 (n=5). The total NIH-FSH-P1 dose given to each donor on the superovulatory treatment was 260, 200 and 160 mg for G1, G2 and G3, respectively. The mouflons in G3 were maidens, while the others were multiparous. Domestic Corriedale ewes (n=60) were synchronized and used as recipients. The embryo recovery and transfer was performed by a surgical method. Mouflons (n=13) responded to the superovulatory treatment with an average of 9.1+/-2.8 ovulations. A low incidence of early luteal regression was found (1 out of 14 donors). Embryo recovery rates were 60, 31 and 76% in groups G1, G2 and G3, respectively. The percentage of transferable embryos obtained in G1 and in G2 exceeded 80%. None of the embryos obtained from G3 were of transferable quality. In G1, 25 transferable embryos were recovered and transferred to 13 recipients, resulting in a pregnancy rate of 76.9% (10/13). In G2, 10 embryos were transferred to 5 recipients, resulting in a 60% pregnancy rate (3/5). Lambing rate was 60% (15/25) and 30% (3/10) for G1 and G2, respectively. Thirteen lambs were born to the 14 donors following natural service after the embryo recoveries. This study demonstrates that the application of IET technology would have great reproductive impact, especially when the donor mouflon hinds are selected according to age and reproductive history.     

Mitochondrial DNA variation of domestic sheep (Ovis aries) in Kenya

The history of domestic sheep (Ovis aries) in Africa remains largely unknown. After being first introduced from the Near East, sheep gradually spread through the African continent with pastoral societies. The eastern part of Africa was important either for the first diffusion of sheep southward or for putative secondary introductions from the Arabian Peninsula or southern Asia. We analysed mitochondrial DNA control region sequences of 91 domestic sheep from Kenya and found a high diversity of matrilines from the widespread haplogroup B, whereas only a single individual from haplogroup A was detected. Our phylogeography analyses of more than 500 available mitochondrial DNA sequences also identified ancestral haplotypes that were probably first introduced in Africa and are now widely distributed. Moreover, we found no evidence of an admixture between East and West African sheep. The presence of shared haplotypes in eastern and ancient southern African sheep suggests the possible southward movement of sheep along the eastern part of Africa. Finally, we found no evidence of an extensive introduction of sheep from southern Asia into Africa via the Indian Ocean trade. The overall findings on the phylogeography of East African domestic sheep set the grounds for understanding the origin and subsequent movements of sheep in Africa. The richness of maternal lineages in Kenyan breeds is of prime importance for future conservation and breeding programmes.     

Embryo recovery from superovulated mouflons (Ovis gmelini musimon) and viability after transfer into domestic sheep

In this study multiple ovulation and embryo transfer (MOET) technology was tested as a method for increasing the number of offspring obtained from superovulated mouflons and then using Sardinian ewes as recipients. Two experiments were carried out over consecutive years. In Experiment 1, female mouflons received a standard superovulatory treatment during both breeding and anoestrous seasons. Sarda sheep, used as controls, received the same treatment. Mean superovulatory response (corpora lutea and large follicles) was higher in the domestic sheep than in the mouflons (4.8 vs. 10.1 and 4.2 vs. 8.8 in breeding and anoestrous seasons, respectively; P < 0.05). A high percentage of mouflons showed early luteal regression which negatively affected recovery rate (35% and 30% in mouflons vs. 69% and 71% in sheep) and the yield of embryos suitable for transfer (37% and 25% in mouflons vs 74% and 69% in sheep; P < 0.05). In Experiment 2, ten mouflons were treated by the same superovulatory protocol and divided into two groups. In the first (Group 5), embryos were recovered earlier by oviductal flushing and cultured in vitro with oviductal cells in CZB medium until the morula/blastocyst stage; in the second (Group 6), the usual embryo recovery time was followed. Recovery rate was higher in the former (89% vs. 31%; P < 0.01) than in the latter. After 4 days of culture, 53% of embryos reached compact morula or early blastocyst stage (16/30). Lambing rate was 57% for mouflon embryos transferred immediately and 56% for those cultured in vitro for 4 days; the lambing rate in the sheep control group was 71%. The length of gestation was longer in ewes carrying mouflons than in those carrying lambs (155 vs. 148 days).     

Influence of age on the relationship between annual changes in horn growth rate and prolactin secretion in the European mouflon (Ovis gmelini musimon)

Annual variations in the growth of horns, and their correlation with seasonal changes of testicular size, and prolactin (PRL) and melatonin secretion were monitored in six pubertal mouflon rams living in their original latitude (40 degrees N). Mouflons born and maintained under captive conditions were classified in two age classes: sub-adult (2 years; n=3) and adult (> or =3 years; n=3). The rate of horn growth was greater (P <0.001) in sub-adult than in adult mouflon rams. Horn growth was influenced by season in both adult and sub-adult mouflons (P <0.05) with largest monthly growth occurring in spring and summer. Seasonal variations of plasma PRL concentrations were correlated with horn growth in adult, but not in sub-adult mouflon rams. The rate of horn growth was inversely correlated with testicular size (r=-0.5, P=0.07). Seasonal changes in the amplitude of the daily melatonin rhythm in solstices and equinoxes were observed, which were not correlated with variations in the rate of horn growth. These results provide support for a possible role of PRL in the control of growth of horns in the adult mouflon.     

Resolving ambiguities in the karyotype of domestic sheep (Ovis aries)

Internally consistent G-, Q- and R-banded karyotypes and idiograms for sheep chromosomes at the 422-band level of resolution are presented. These were derived by sequential Q- to G-staining, and sequential Q- to R-staining of prometaphase spreads prepared from sheep with normal and Robertsonian chromosomes. The fused chromosomes served as stable morphological markers. To minimise confusion due to chromosomal nomenclature, we have listed chromosome-specific (reference) molecular markers that have been mapped byin situ hybridization to sheep chromosomes. The use of molecular markers in conjunction with the sequential Q- to G- and sequential Q- to R-banded karyotypes and iodiograms provided here will elimiate ambiguities in identifying and numbering sheep chromosomes and will facilitate their comparison with cattle chromosomes. Edited by: J.B. Rattner     

Resolving ambiguities in the karyotype of domestic sheep (Ovis aries)

The unambiguous identification of ovine chromsomes has become essential for the mapping of the sheep genome, which predominantly consists of telocentric chromosomes of gradually decreasing size. Nucleolus organizer regions (NORs) and Robertsonian fusions have been used here as the cytological and morphological markers, respectively, to define the banding pattern of eight paris of sheep telocentric chromosomes that have an ambiguous identification status. Five Robertsonian chromosomes involving most of the ambiguous chromosomes as well as normal prometaphase chromosomes were stained sequentially and separately by QFQ, GTG, and Ag-NOR methodologies. The prometaphase banding patterns of the ambiguous chromosomes 4, 6, 8, 9, 21, 24, 25 and 26 are represented schematically. For providing an accurate image of the banding pattern, a system of shading has been employed to show the relative intensity of bands in a given chromosome. The results presented here will facilitate the regional mapping of the sheep genome, extend the information on cytogenetic homology with other bovids, and substantially accelerate the comparative mapping studies in Bovidae.     

Origin of the preovulatory follicle in Mouflon sheep (Ovis gmelini musimon) and effect on growth of remaining follicles during the follicular phase of oestrous cycle

Daily transrectal ultrasonographies were conducted to study development of all follicles with antral diameters > or = 2mm during the follicular phase of oestrous cycle in Mouflon, a strictly monovular wild-sheep. A total of 14 follicular phases was studied after oestrus synchronization with two cloprostenol doses, 9 days apart, in five cyclic Mouflon ewes. In 13 cycles (92.8%), the ovulatory follicle arose from those antral follicles present in both ovaries when luteolysis was induced, being the largest one with a mean size of 4.4+/- 0.3mm at that moment in 10 cycles (76.9%). The remaining cycles had a larger follicle, but it was decreasing in size. Appearance of new follicles > or =2mm in size remained unaffected during the follicular phase (3.7+/- 0.2), but there was found a linear decrease in the number of those growing to > or =3mm (2.5+/- 0.4 to 1.1+/- 0.2, P < 0.05) and > or = 4mm (0.6+/- 0.2 to 0.1+/- 0.1, P < 0.005), detection of new follicles growing to > or = 5mm was negligible. Then, number of medium (4-5mm) growing follicles present in both ovaries decreased from 1.5+/- 0.3 at 0 h to 0.3+/- 0.1 at 72 h (P<0.005). In conclusion, the single ovulatory follicle is the largest growing follicle present in both ovaries at the moment of luteolysis. This follicle is selected to grow and ovulate while development of other follicles is inhibited.     

Ecology and behaviour of domestic sheep (Ovis aries): a review

Behaviour of sheep is complex and poorly understood. It is only within the past 20 years that a concerted effort has been made to elucidate those aspects of behaviour which have most relevance to sheep raising under open-range conditions. The present report attempts to summarize and review published work on the behaviour and ecology of sheep. The whole question of the significance of behaviour and the extent to which it is possible to shape it is a field which is open for study. This paper is an attempt to summarize the work on sheep behaviour and on those aspects of physiology which impinge. Consideration is given to the evolution of Bovids, scope of domestication and world distribution of sheep since these aspects have a major influence on the sheep with which we deal today. Animal requirements for food, water, shelter, protection from predators, and control of disease and parasites have been largely met by man and the forces for selection which operated among the progenitors of domestic sheep have been largely negated. Despite this, genetic selection still goes on. Behavioural adaptation to a wide variety of environmental and nutritional regimes is a common feature among free-ranging sheep. Reproductive success, a matter of considerable commercial concern is often poor. Lamb survival is of critical importance. Factors involved in neonatal mortality are reviewed in detail. Finally, the now extensive literature on sheep behaviour, physiology and management is collated in a bibliography with over 150 literature citations.     

Bloat in sheep (Ovis aries)

1. Most of the field studies on bloat are conducted with cattle and most of the laboratory experiments seeking to explain the various parameters associated with bloat are done with sheep. 2. Based on grazing behaviour, it would be expected that sheep might bloat more severely than cattle because they selectively choose to eat leaves over stems and chew what they ingest more frequently than cattle. Furthermore, sheep appear to select legumes over grasses because the legumes can be eaten more rapidly. However, because they are selective, sheep eat more slowly than cattle. Despite a higher bloat expectation, bloating in sheep is reported to be less of a problem than in cattle. 3. Although frothing of rumen ingesta was described earlier in cattle as the cause of acute legume bloat, experiments with frothy bloat in sheep preceded those in cattle. 4. Anti-frothing agents were used in sheep before cattle to treat acute legume bloat. 5. Experiments devoted to the study of eructation in ruminants were carried out on sheep, then cattle. 6. Convincing evidence that rumen motility does not cease during acute legume bloat was gathered using sheep. 7. Although the transected tracheal technique for the determination of the volume of eructated gas was developed with cattle, the pathway of eructated gas was confirmed with sheep. 8. All the current evidence accumulated from experiments with sheep supports the hypothesis that death due to legume bloat is caused by acute neural, respiratory, and cardiovascular insult resulting from the effect of the distended rumen on thoracic viscera, diaphragm, intercostal muscles, and the abdominal vena cava. 9. Experiments with sheep and cattle being fed scabrous and nonscabrous diets similar in chemical composition show that sheep are more resistant than cattle to the increase in intrarumen pressure, decline in rumen contraction amplitude, and decrease in rumen contraction frequency caused by nonscabrous diets. 10. The sequence of events in the reticulorumen during primary and secondary contractions previously described following visual and palpation experiments with cattle was confirmed by the use of myoelectrodes implanted in the various sacs of the reticulorumen of sheep. 11. Elevated intrarumen pressure is associated with an increase in the frequency of primary (mixing) and secondary (eructation) contractions (more secondaries than primaries).(ABSTRACT TRUNCATED AT 400 WORDS)     

Survival of bighorn sheep (Ovis canadensis) commingled with domestic sheep (Ovis aries) in the absence of Mycoplasma ovipneumoniae

To test the hypothesis that Mycoplasma ovipneumoniae is an important agent of the bighorn sheep (Ovis canadensis) pneumonia that has previously inevitably followed experimental commingling with domestic sheep (Ovis aries), we commingled M. ovipneumoniae-free domestic and bighorn sheep (n=4 each). One bighorn sheep died with acute pneumonia 90 days after commingling, but the other three remained healthy for >100 days. This unprecedented survival rate is significantly different (P=0.002) from that of previous bighorn-domestic sheep contact studies but similar to (P>0.05) bighorn sheep survival following commingling with other ungulates. The absence of epizootic respiratory disease in this experiment supports the hypothesized role of M. ovipneumoniae as a key pathogen of epizootic pneumonia in bighorn sheep commingled with domestic sheep.     

Rank Acquisition Through Birth Order in Mouflon Sheep (Ovis gmelini) Ewes

The relationship between mothers' and daughters' dominance ranks was studied in a captive herd of mouflon sheep ( Ovis gmelini ), including nine adult ewes and their daughters, observed as lambs and yearlings. We found a positive correlation between the ranks of mothers and those of their yearling daughters, even though every mother dominated all the yearlings. We then tested the hypothesis that daughters from subordinate ewes became subordinate within their own age class because, as lambs, they had received more aggression from the other ewes in the herd. Recorded data were inconsistent with the hypothesis, even showing a trend for female lambs to receive aggression more frequently when born from dominant ewes. We also tested the hypothesis that resemblance between mothers' and daughters' ranks was due to inheritance of aggressiveness. No significant correlation was found between mothers' and daughters' aggressiveness, so the hypothesis was not supported. Finally, we found a significant concordance between mothers' ranks, daughters' ranks, and daughters' birth dates. Earlier-born daughters became dominant over later-born ones, probably because of larger body size and more advanced social behaviour. The age of most of the mothers was undetermined, but in mouflon sheep, older ewes generally dominate younger ewes and are known to lamb earlier during the birth season. Accordingly, it is suggested that dominant ewes have daughters dominant in their own age class, because (1) age influences the parturition date during the birth season, and (2) age strongly influences rank, even in individuals born during the same lambing season.     

Y chromosome haplotype diversity of domestic sheep (Ovis aries) in northern Eurasia

Variation in two SNPs and one microsatellite on the Y chromosome was analyzed in a total of 663 rams representing 59 breeds from a large geographic range in northern Eurasia. SNPA‐oY1 showed the highest allele frequency (91.55%) across the breeds, whereas SNPG‐oY1 was present in only 56 samples. Combined genotypes established seven haplotypes (H4, H5, H6, H7, H8, H12 and H19). H6 dominated in northern Eurasia, and H8 showed the second‐highest frequency. H4, which had been earlier reported to be absent in European breeds, was detected in one European breed (Swiniarka), whereas H7, which had been previously identified to be unique to European breeds, was present in two Chinese breeds (Ninglang Black and Large‐tailed Han), one Buryatian (Transbaikal Finewool) and two Russian breeds (North Caucasus Mutton‐Wool and Kuibyshev). H12, which had been detected only in Turkish breeds, was also found in Chinese breeds in this work. An overall low level of haplotype diversity (median h = 0.1288) was observed across the breeds with relatively higher median values in breeds from the regions neighboring the Near Eastern domestication center of sheep. H6 is the dominant haplotype in northwestern and eastern China, in which the haplotype distribution could be explained by the historical translocations of the H4 and H8 Y chromosomes to China via the Mongol invasions followed by expansions to northwestern and eastern China. Our findings extend previous results of sheep Y chromosomal genetic variability and indicate probably recent paternal gene flows between sheep breeds from distinct major geographic regions.