Active Rams Research Articles

Dietary n-3 PUFA augments pre-ovulatory follicle turnover and prolificacy in well-fed ewes

The present study evaluated the effect of dietary supplementation with n-3 polyunsaturated fatty acids (PUFA) on preovulatory follicle (POF) turnover, prolificacy, and endocrine and metabolic milieu in Malpura sheep. Fifty cyclic ewes with 3–3.5 body condition scores on a five-point scale were allocated equally to two groups (n = 25) following estrus synchronization and were supplemented with 0.6 mL/kg body weight of n-3 PUFA-rich fish oil (FO) or palm oil (PO) as control, for 60 d following an acclimatization period of 7 d. All ewes were mated with sexually active rams at the end of the supplementation period. On ultrasonographic ovarian scanning at the last fourth estrus, the mean number of POFs was 77.8% greater (P < 0.01) in FO ewes than in the PO ewes. The proportion of ewes with multiple ovulations two months after the beginning of supplementation was 56% in the FO group as compared to 8% in the PO group. The number of fetuses was 46% higher (P < 0.01) in the FO than in the PO ewes at d 45 of gestation. At lambing, the twinning percent in the FO ewes was three times greater than in the PO ewes (27.3 vs. 9.1%). Plasma cholesterol, estradiol, and insulin concentrations were lower (P < 0.01) in ewes fed with FO than those offered PO group at the end of the feeding period. It was concluded that the dietary supplementation of n-3 PUFA-rich FO in well-fed Malpura ewes improved the number of follicles and ovulation rate which led to an increased prolificacy, accompanied by a reduction of plasma cholesterols, estradiol, and insulin.

Blood transcriptome of Rasa Aragonesa rams with different sexual behavior phenotype reveals CRYL1 and SORCS2 as genes associated with this trait.

Reproductive fitness of rams is seasonal, showing the highest libido during short days coinciding with the ovarian cyclicity resumption in the ewe. However, the remarkable variation in sexual behavior between rams impair farm efficiency and profitability. Intending to identify in vivo sexual behavior biomarkers that may aid farmers to select active rams, transcriptome profiling of blood was carried out by analyzing samples from 6 sexually active (A) and 6 nonactive (NA) Rasa Aragonesa rams using RNA-Seq technique. A total of 14,078 genes were expressed in blood but only four genes were differentially expressed (FDR < 0.10) in the A vs. NA rams comparison. The genes, acrosin inhibitor 1 (ENSOARG00020023278) and SORCS2, were upregulated (log2FC > 1) in active rams, whereas the CRYL1 and immunoglobulin lambda-1 light chain isoform X47 (ENSOARG00020025518) genes were downregulated (log2FC < -1) in this same group. Gene set Enrichment Analysis (GSEA) identified 428 signaling pathways, predominantly related to biological processes. The lysosome pathway (GO:0005764) was the most enriched, and may affect fertility and sexual behavior, given the crucial role played by lysosomes in steroidogenesis, being the SORCS2 gene related to this signaling pathway. Furthermore, the enriched positive regulation of ERK1 and ERK2 cascade (GO:0070374) pathway is associated with reproductive phenotypes such as fertility via modulation of hypothalamic regulation and GnRH-mediated production of pituitary gonadotropins. Furthermore, external side of plasma membrane (GO:0009897), fibrillar center (GO:0001650), focal adhesion (GO:0005925), and lamellipodium (GO:0030027) pathways were also enriched, suggesting that some molecules of these pathways might also be involved in rams' sexual behavior. These results provide new clues for understanding the molecular regulation of sexual behavior in rams. Further investigations will be needed to confirm the functions of SORCS2 and CRYL1 in relation to sexual behavior.

Sex or maternal care? Nursing oestrous ewes prefer to interact with rams over their lambs

In some sheep production systems, the ewes are induced to come into oestrus whilst nursing their lambs. After that, mothers and offspring are usually moved into a paddock with sexually active rams leading to a conflict between sexual and maternal motivations. The aim of this study was to determine if a nursing oestrous ewe prefers its lamb or a sexually active ram in a two-choice test with full physical contact. During the breeding season, 23 multiparous Corriedale ewes nursing single lambs were induced to come into oestrus 72 days after parturition. Twenty ewes came into oestrus and were tested in a two-choice test with full physical contact between their single lamb and a sexually active ram. The latency to enter into a contact area surrounding each stimulus (ram or lamb) and the time spent in each area were recorded for 3 min. The number of vocalisations emitted by the lambs and the sexual behaviour displayed by the rams were also recorded. One nursing oestrous ewe did not enter any defined area and was excluded from the analysis, which included 19 tests. Nursing oestrous ewes entered earlier (X2 =8.05; P = 0.005; Survivance test) and stayed longer (Z = −2.74; P = 0.006; Wilcoxon Signed-Rank test) in the ram's contact area than in the lamb's contact area. During the test, rams almost always displayed sexual behaviours when ewes entered their contact area (17/19 tests). The lambs vigorously vocalised during the test (19.7 ± 2.5 bleats/test), but the number of vocalisations was not related to the time the ewe spent near the lamb or the ram. In conclusion, nursing oestrous ewes strongly prefer sexually active rams over their lambs during the breeding season. This result gives rise to a greater understanding of sexual behaviour in the ewe, which may very well impact the reproductive management of sheep.

Exposure of rams in sexual rest to sexually activated males in spring increases plasma LH and testosterone concentrations

Eight stimulating rams, and twelve stimulated rams, were used to determine whether a similar endocrine response to the introduction of sexually active males in spring in a flock of ewes is observed in a flock of rams. The stimulating rams (n = 4) were induced into a sexually active state by exposure to 2 months of long days (16 h light/d) (15 December-15 February). At the end of the long-day period, rams were returned to the natural photoperiod. Control-stimulating rams (n = 4) were kept under the natural photoperiod. On April 20, stimulated rams were divided into 2 groups, and joined with activated (ACT; n = 6) or control stimulating rams (C; n = 6). On the day of ram introduction, stimulated rams were blood sampled for 8 h at 20-min intervals, from 4 h before to 4 h after ram introduction, and next day from 24 to 28 h after ram introduction, and analyzed for plasma LH concentrations, and 10, 20 and 30 days after ram introduction to measure plasma testosterone levels. Mean (±SEM) plasma LH concentrations (ng/ml) of stimulated rams were similar during the 4 h before stimulating-ram introduction (ACT: 0.59 ± 0.03; C: 0.53 ± 0.04; P > 0.05). The introduction of the photoperiod-treated stimulating rams increased LH concentrations of stimulated rams during the 4 h after their introduction (1.14 ± 0.37) compared with the C group (0.51 ± 0.03; P < 0.05), especially during the first hour (ACT: 0.93 ± 0.16; C: 0.49 ± 0.03; P < 0.05), and during the blood sampling period 24–28 h after ram introduction (0.75 ± 0.07 vs. 0.58 ± 0.04; P < 0.05). Before the introduction of stimulating rams, the LH pulse frequencies and amplitudes did not differ between groups; however, LH pulsatility was higher at 4 h (0.58 ± 0.11 pulses/h; P < 0.05), and had trend to be higher 24 h (0.50 ± 0.06) (P = 0.10) after the introduction of the photoperiod-treated stimulating rams compared with the control-stimulating rams (0.29 ± 0.08 and 0.29 ± 0.10, respectively). As for LH pulses, there was an effect of group (P < 0.05) on LH amplitude, which presented a trend to be higher in ACT rams 4 h after ram introduction (1.68 ± 0.30; P < 0.10) and higher 24 h (1.07 ± 0.08; P < 0.05) after ram introduction, compared with LH amplitudes of C rams (0.71 ± 0.06 and 0.82 ± 0.07, respectively). Plasma testosterone concentrations of rams exposed to photoperiod-treated activated rams were higher than those of rams exposed to control-stimulating rams, at 4 h, 20 and 30 days after ram introduction (P < 0.05). In conclusion, sexually active rams in spring are able to stimulate LH and testosterone secretion of other rams in sexual rest, a phenomenon we called “ram-to-ram effect".

Biostimulation with the ram effect increases the follicle recruitment, ovulatory diameter, and embryo viability rate in superovulated ewes

The aim of this study was to compare the preovulatory follicular development and superovulatory outcomes in superovulated ewes which were either stimulated or not stimulated by placement with rams. The treatment regimen to super-stimulate ovarian follicular development was imposed to 28 ewes on “Day 0”, from which 14 were stimulated with active rams for 48 h, starting at the time of the fifth FSH dose, with the ram being removed from the pen with the ewes and replaced which other ram every 12 h, using four different rams (group GRE). The other 14 ewes remained isolated from rams throughout the protocol (group GCON). All ewes were administered 133 mg of FSH, into six doses in decreasing quantities, every 12 h. The follicular development and number of ovulations were determined using ultrasonography. Biostimulation resulted in an increased number of large follicles, follicle diameter, and embryo viability rate (viable embryos/recovered structures∗100) was greater in ewes of the GRE than GCON group. The number of corpora lutea, follicular cysts, recovered structures, viable embryos, and degenerated and unfertilized structures was similar in ewes of the GRE and GCON group. Structures were recovered from more GRE than GCON ewes. In conclusion, biostimulation with rams during the last phase of the treatment regimen to induce superovulation enhanced the follicular growth and increased the embryo viability rate in ewes.

Light-induced sexually active rams provoke LH preovulatory surges and enhances LH concentrations in ewes after progestagen treatment.

The effect of the introduction of sexually active rams in spring on LH secretion in ewes after progestagen treatment has been studied. Two rams were induced into a sexually active state by exposure to 2 months of long days (16 h of light/d) from 1 January (SAR), and another 2 rams were exposed to the natural photoperiod, so that they were not sexually activated in spring (control; C). At the end of the long-day period, rams were returned to natural photoperiod conditions. Fifteen ewes synchronized in estrus by intravaginal sponges were assigned to three groups at sponge withdrawal (hour 0): SAR (n = 5), exposed to SAR rams; C (n = 5), exposed to C rams, and ISO (n = 5), kept isolated from rams. Twenty-four hours after pessary removal (hour 0), rams were introduced into the SAR and C groups. Three SAR ewes presented preovulatory LH surges; the proportion was significantly (P < 0.05) higher in this group (3/5) than in the others (C: 0/5, ISO: 0/5). SAR introduction induced a more marked (P < 0.05) increase in mean LH plasma concentrations (before rams: 1.34 ± 0.19; after rams: 6.94 ± 2.66 ng/ml) than C (before: 0.96 ± 0.29; after: 3.60 ± 1.44) or ISO (before: 1.26 ± 0.42; after: 2.14 ± 1.36) groups, and significantly (P < 0.05) higher plasma LH levels after ram introduction. In conclusion, only light-treated sexually activated rams induced LH preovulatory surges in ewes in the seasonal anestrus, when ewes are synchronized with progestagen treatment in the absence of eCG.

Light-induced sexually active rams prevent the seasonal inhibition of luteinizing-hormone in ovariectomized estradiol-implanted ewes

The effect of the continuous presence of sexually active Rasa Aragonesa rams on the plasma luteinizing-hormone (LH) concentrations of ewes was studied from November to May. Light-treated rams were rendered sexually active (SA rams) by exposure to 2 months of artificially long days (16 h light/8 h dark) in one of two groups from either 1 November (SAR1, n = 3) or 1 December (SAR2, n = 3). Rams (n = 6) in a Control group were kept under the natural photoperiod. Thirty ewes were ovariectomized in September and implanted with a subcutaneous implant (l = 15 mm) that contained estradiol-17β. One group of ewes (SAR; n = 10) was housed with control rams from 1 October to 15 February before being housed with SAR1 rams from 16 February to 31 March, and with SAR2 rams from 1 April to 31 May. A second group of ewes (C; n = 10) remained with control rams throughout the experiment, and a third group was kept isolated from rams throughout the experiment (ISO; n = 10). Blood samples were collected weekly from November to May, and plasma LH concentrations were measured. In the breeding season (November–February), plasma LH concentrations of ewes did not differ significantly between groups (SAR: 2.00 ± 0.34; C: 1.88 ± 0.16; ISO: 1.67 ± 0.51 ng/ml). From March to May (seasonal anestrus), however, LH plasma concentrations decreased in the C and ISO groups (1.30 ± 0.20 and 0.48 ± 0.04 ng/ml, respectively), but remained at the same level as in the breeding season in the SAR group (2.30 ± 0.17 ng/ml; P < 0.001). Significant differences (P < 0.01) between groups were observed from March onwards: LH concentrations were highest in SAR ewes (P < 0.001) and lowest in the ISO ewes. In conclusion, the continuous presence of sexually active rams prevented the seasonal decrease in plasma LH concentrations, probably by preventing the seasonal negative feedback of estradiol on LH secretion.

Long days in winter or the presence of adult sexually active rams did not influence the timing of puberty of autumn-born Rasa Aragonesa ram-lambs

ABSTRACT Forty autumn-born ram-lambs were used to study the effect of several rearing strategies on their sexual activity and fertility at 8 months of age. The animals were assigned to one of the following four groups (n = 10): FA, which were exposed to 2 months of long days (15 January–15 March); SAR, which were housed with three Sexually Activated adult Rams from 15 March to 20 June; NAR, housed with three Nonactivated adult Rams, and Control (C), kept isolated from adult rams throughout the experiment. In mid-June, individual and group ram serving-capacity tests were performed. Mean plasma testosterone levels (ng/ml) throughout the experiment were higher (P < 0.001) in the C (4.4 ± 0.2) and SAR (4.3 ± 0.2) groups than in the FA (3.4 ± 0.2) and NSA (3.4 ± 0.2) groups. In the serving tests, control ram-lambs executed a higher total mean number of sexual events than the other groups (P < 0.05). Fertility rates of SAR- (90%) or C-mated ewes (100%) were higher (P < 0.01) than ewes mated by the FA (50%) and NAR (40%) ram-lambs. In conclusion, autumn-born ram-lambs reared in isolation from adult congeners had the highest sexual activity and fertility at 8 months of age, which suggests that no special rearing strategy is necessary to induce puberty in these rams.

Ewes express increased proceptive behavior toward high-sexually active rams

Variable expression of male reproductive behavior has been observed in all species studied. Approximately 25% of male sheep exhibit low sexual interest, but usually mate and have limited numbers of offspring. In domesticated, promiscuous species like sheep, the female may have mate preference, but mate choice is usually constrained by breeding strategies. It was hypothesized that when mate choice is limited, ewes would exhibit more proceptive behavior toward rams with low sexual interest to ensure reproductive success. Recorded serving capacity tests (n = 56) were utilized for this analysis. Rams were individually exposed to two ewes in estrus with behavior recorded for 20 min. From those recordings, a 10 min time period was utilized to assess ewe proceptive behavior. Ram anticipatory and consumatory behaviors were recorded. Anticpatory behaviors included ano-genitial sniffs, vocalization, fore-leg kicks, head butts, and nudges. Consumatory behavior included mount attempts, mounts, and ejaculations. Rams were categorized as high performing if they achieved two or more mounts during the 10 min period. Ewe behavior was determined by the number of solicitation looks and movements toward and away from the ram. During the 10 min of observed behavior, time spent in close proximity (less than 0.3 m) to the ram was determined and considered time in affiliation with the ram. Percent of time spent in affiliation with high sexually performing rams was greater (P < 0.001) 57.7% (±3.3) than when exposed to rams exhibiting low sexual behavior (23.8% [±3.4]). Affiliation time was highly correlated (P < 0.001; r2 ≥ 0.6) with ram behaviors: number of mounts, total anticipatory, and consummatory behavior. High sexually performing rams garnered more (P < 0.001) solicitous looks from ewe than did low performing rams. Ewes exhibited increased number of purposeful moves toward (P = 0.02), but not away (P = 0.58) from, high performing rams. These data indicate that ewes express more proceptive behavior toward rams expressing greater sexual interest. In conclusion, ewe behavior does not compensate for low sexual interest from the ram and would not be expected to contribute to the reproductive success of rams expressing low sexual interest.

Serosurvey of Q fever in active reproductive rams in northern Palestine

This investigation of Q-fever or Coxiellosis was undertaken to study the presence and the infection rate of C.burnetii infection in reproductively active rams in the Northern Palestine, where most of the sheep herds are located. In all, 2806 samples which collected from active rams during the reproductive season from herds in five cities (Jenin, Jericho, Nablus, Tulkarm and Tubas). Sera were tested by ID Screen® Q Fever Indirect Multi-species enzyme-linked immunosorbent assay (ELISA) for detection of C. burnetii immunoglobulin G (IgG). A total of 28.1 % of ram sera were positive for C. burnetii IgG. There was no significant difference between the four location cities studied However, a significantly low difference was observed in the Tubas city (P<0.05). Highest infection rate was detected in rams of Tulkarm (29.8%), followed by Nablus (29.5%), Jericho (28.4%), Jenin (28.2%) and Tubas (16.1%). Moreover, at the farm level, 73.3% had at least one seropositive animal. It had been concluded that a high infection rate were detected in rams of Northern Palestine, at both individual and herd level. Therefore, Q fever could be responsible for considerable numbers of ovine abortions in Palestine, as well as of public health significance, Hereby control programs should be advised.

Tyrosine hydroxylase in the ventral tegmental area of rams with high or low libido—A role for dopamine

Dopamine synthesis in the ventral tegmental area (VTA) is necessary for the reinforcement of sexual behavior. The objective of this study determined if sexual stimuli initiates reward, and whether reward is attenuated in sexually inactive rams. Sexually active rams were exposed to urine from estrous (n=4) or ovariectomized (n=3) ewes with inactive rams (n=3) exposed to urine from estrous ewes. Following exposure, rams were exsanguinated and brains perfused. Alternating sections of the VTA were stained for Fos related antigens (FRA), tyrosine hydroxylase, and dopamine beta-hydroxylase activity. Forebrain tissue, mid-sagittal ventral to the anterior corpus callosum, was stained for dopamine D2 receptors. Concentrations of cortisol was determined prior to and following exposure. Exposure to ovariectomized-ewe urine in sexually active rams did not influence (P=0.6) FRA expression, but fewer (P<0.05) neurons were positive for tyrosine hydroxylase in the VTA. Sexually inactive rams had fewer (P<0.05) FRA and tyrosine hydroxylase positive neurons in the VTA than sexually active rams following exposure to estrous ewe urine. VTA neurons staining positive for dopamine beta-hydroxylase did not differ by sexual activity (P=0.44) or urine exposure (P=0.07). Exposure to stimulus did not influence (P=0.46) numbers of forebrain neurons staining positive for dopamine D2 receptors in sexually active rams, but fewer (P=0.04) neurons stain positive in inactive rams. Serum concentrations of cortisol did not differ (P≥0.52) among rams prior to or following stimulus. In conclusion sexual inactivity is unlikely due to stress, but may be partially a result of decreased tyrosine hydroxylase and/or the response to dopamine.

Effet de l’acide ascorbique sur le taux de fécondation des brebis Yankasa après synchronisation de l’œstrus

L’objectif de cette étude était d’évaluer les effets d’une admi­nistration d’acide ascorbique (AA) sur le taux de fécondation de brebis dont les chaleurs étaient induites par deux traite­ments à base de progestogènes. Des brebis de race Yankasa (n = 64) ont été réparties de façon égale en deux groupes. Dans l’un, les brebis ont été traitées avec un dispositif intra­vaginal de libération continue du médicament (CIDR). Dans l’autre, les brebis ont été traitées avec 45 mg d’acétate de fluo­rogestone (FGA) au moyen d’une éponge vaginale. Après le retrait des progestogènes, les brebis de chaque groupe expri­mant des chaleurs ont été réparties en quatre sous-groupes : CIDR témoin (CDNN, n = 12), CIDR plus AA (CDAA, n = 11), FGA témoin (FGNN, n = 13) et FGA plus AA (FGAA, n = 12). La détection des chaleurs a été réalisée au moyen de béliers sexuellement actifs et laissés libres de s’accoupler avec les femelles. Le taux d’expression des chaleurs n’a pas différé entre les sous-groupes. L’intervalle entre le retrait des dis­positifs et l’apparition des chaleurs a été significativement (p &lt; 0,05) plus court chez les brebis du groupe FGA que chez celles du groupe CIDR (respectivement 30,35 ± 2,72 et 48,56 ± 7,52 heures). La durée de l’oestrus n’a pas différé (p &lt; 0,05) entre les traitements (FGA 37,22 ± 4,22 et CIDR 39,75 ± 2,51 heures). Les taux de fécondation ont été comparables entre sous-groupes. En conclusion, l’administration d’AA lors du retrait des dispositifs progestogéniques n’a pas amélioré le taux de fécondation des brebis Yankasa.

Evaluation of production and reproduction of three South African Angora goat &lt;i&gt;CYP17&lt;/i&gt; genotypes

Two CYP17 genes, located on different loci and expressing enzymes with significantly different activities, have been identified in the South African Angora goat population. Three unique genotypes (named H e , H u , and H o ), which differed not only in the genes encoding CYP17 , but also in copy number were subsequently identified in the Angora goat. The aim of this study was to evaluate the production and reproduction performance of these three genotypes. Bodyweight, fleece and reproduction data, and blood samples from 466 Angora ewes from three flocks were obtained from the GADI-Biobank. Data had been collected on Flock 1 from 2000 to 2015, Flock 2 from 2000 to 2014 and Flock 3 from 2000 to 2010. Bodyweight data included birth weight, weaning weight, 8-, 12-, and 16-month bodyweight, as well as bodyweight recorded annually for the ewe flock before mating. Fleece data included fleece weight and fibre diameter recorded at the second and third shearings at 12 and 18 months old, respectively. Fleece weight, fibre diameter, style and character were also recorded annually for the ewe flocks during the winter shearing. Individual reproduction records included information on whether the ewe had kidded, whether the ewe had aborted, number of kids born, stillborn kids, kids that died soon after birth, kids reared by a foster mother, kids reared as orphans, number of kids weaned and total weight of kids weaned. Total lifetime reproductive performance of genotyped ewes was calculated for number of kids born, number of kids weaned, and total weight of kids weaned. Blood samples were also collected from 100 sexually active Angora rams from four sources. CYP17 genotyping was carried out using an ARMS-qPCR (amplification refractory mutation system qPCR) assay. Serum testosterone was quantified using high performance liquid chromatography mass spectrometry. The distribution of the ewes across the three CYP17 genotypes was 36.7% H e , 51.5% H u , and 11.8% H o , and was in accordance with the distribution of the Angora veld rams (38.0% H e , 46.4% H u , and 15.6% H o ). In this study, animals of the H u genotype were heavier from weaning age onwards, although this difference in bodyweight was significant only at 8 months old and in the adult ewes. No differences were observed between the H e and H o animals. Adult ewes of the H e genotype (1.35 kg) produced heavier ( P 0.05). No significant differences were recorded in reproductive performance among the genotypes, although the H o ewes had the lowest (1.03 and 0.89) and the H e ewes the highest (1.07 and 0.93) number of kids born and weaned per year respectively. Results on the rams indicated that the CYP17 genotype had no effect on testosterone production by Angora rams. From the results of this study no evidence could be found that selection for any of the three genotypes would adversely affect any growth, mohair production or reproduction function of Angora ewes. A breeding strategy incorporating selection for productive traits and the CYP17 genotype, aimed at increasing the frequency of the ACS+ gene and thus the He genotype in the population, could be followed without having a negative effect on the genetic progress of productive traits. Keywords: Bodyweight, fleece weight, number of kids weaned, testosterone, weight of kids weaned

The relationships between body fatness, leptin, testosterone, and reproductive performance in ram lambs as affected by level and frequency of feeding

This study was carried out using 24 Najdi ram lambs of approximately 6.5 months old to evaluate the effects of feed restriction and frequency of feeding on hormone concentrations of leptin and testosterone, sexual behavior, and semen traits. Ram lambs were allotted equally into three feeding groups. The first group was used as a control and fed ad libitum. The second and third groups were restricted fed at 0.85 ad libitum and fed either once (R1M) or twice daily (R2M). Sexual behavior and semen evaluation were assessed during the sixth, seventh, and eighth weeks of the study. Blood samples were drawn at 1-hour pre-feeding on days 41, 48, and 55 of the study for the determination of serum leptin and testosterone concentrations. All lambs were slaughtered after 8 weeks of experimentation. Results showed that the restricted-fed groups had lower (P < 0.01) values for slaughter body weight, average daily gain, dry matter intake, internal fat, tail fat, body fat thickness, body wall thickness, and testes weight than the ad libitum group; these corresponding traits did not differ between both restricted-fed treatments. Leptin and testosterone concentrations in restricted-fed rams were (P < 0.01) lower and higher, respectively, than in the ad libitum rams; there were no differences between R1M and R2M groups. The restricted-fed rams had lower (P < 0.01) ejaculation latency time compared with control, whereas the percentage of sexually active rams and sexual desire score were not affected by feeding restriction or frequency of feeding. Sperm motility, progressive motility, and percentage of sperm moving at rapid speed were higher (P < 0.01) in feed-restricted rams than in the ad libitum rams. R1M rams had higher (P < 0.01) value for straightness and lower (P < 0.01) value for curvilinear velocity in comparison with the ad libitum group. Testosterone was correlated positively (P < 0.05) with sperm motility and progressive motility and negatively (P < 0.04) with fat measurements, leptin, and ejaculation latency time. In conclusion, moderate intake restriction can optimize body fatness and testosterone concentrations in rams, which helped to improve some reproductive traits.

Fos expression in the olfactory pathway of high- and low-sexually performing rams exposed to urine from estrous or ovariectomized ewes

Exposure to estrous ewe urine stimulates investigation and mounting activity in sexually active but not sexually inactive rams. It was hypothesized sexual indifference may result from an inability to detect olfactory cues or an interruption of the pathway from detection of the olfactory stimulus to the motor response. Sexually active (n=4) and inactive (n=3) rams were exposed to urine from estrous ewes. An additional group of sexually active rams (n=3) were exposed to urine from ovariectomized ewes. Rams were exsanguinated following 1h of exposure to stimulus. Neural activity was determined in tissues of interest by the presence of fos and fos-related proteins detected by immunohistochemistry procedures. Sexually active rams exposed to urine from ovariectomized ewes had more (P≤0.05) fos-positive cells in the olfactory bulb, but fewer (P=0.03) fos-positive cells in the cortical amygdala compared to sexually active rams exposed to urine from estrous ewes. Sexually inactive rams had similar (P≥0.13) numbers of fos positive neurons in the olfactory bulb and medial amygdala but fewer (P≤0.04) in the central amygdala, bed nucleus of the stria terminalis and the medial preoptic area compared to sexually active rams exposed to urine from estrous ewes. Sexual inactivity was not associated with decreased hypothalamic function since fos activity was similar (P≥0.14) among groups in the suprachiasmatic and ventral medial nucleus. Sexual inactivity is not likely due to an impaired ability to detect or process olfactory stimuli by the main olfactory bulb and medial-cortical amygdala. Sexually inactive rams may have reduced attentiveness to sexual stimuli and/or decreased responsiveness of regions in the brain which regulate reproductive behaviors.

Continuous exposure to sexually active rams extends estrous activity in ewes in spring

Sexual activity in sheep is under photoperiodic control, which is the main environmental factor responsible for the seasonality of reproduction. However, other natural environmental factors such as presence of conspecifics can slightly influence the timing of onset and offset of the breeding season. In goats, we have found that the continuous presence of bucks that were rendered sexually active out of season by previous exposure to long days, prevented goats from displaying seasonal anestrus, which suggests that the relative contribution of photoperiod in controlling seasonal anestrus should be reevaluated in small ruminant species. The aim of this study was to assess whether the presence of sexually active rams that had been stimulated by artificial photoperiod and melatonin implants, reduces seasonal anestrus in sheep, by prolonging ovulatory activity in spring. Ewes were assigned to one of two groups (n = 16 and 15), which were housed in two separate barns, and kept in contact, either with the treated or the control rams between March and July. Vasectomized rams were either exposed to 2 months of long days followed by the insertion of three subcutaneous melatonin implants (treated rams, n = 8), or exposed to natural light conditions (control rams, n = 2). Estrus was monitored daily, and weekly plasma progesterone analyses indicated ovulatory activity. Ewes that were exposed to treated rams exhibited a higher proportion of monthly estrus than ewes exposed to the control rams (P < 0.05). Thirteen of 15 ewes (one ewe was not considered because of the presence of persistent CL) exposed to stimulated rams exhibited estrous behavior in a cyclic manner. In contrast, all ewes exposed to control rams stopped estrous activity for a period of time during the study, such that this group exhibited a significantly longer anestrous season (mean ± standard error of the mean 89 ± 9 days) than did the ewes housed with treated rams (26 ± 10 days; P < 0.0001). Among 15 ewes housed with treated rams, 13 of them exhibited continuous ovulatory activity between March and July, whereas one stopped in June and two in July. All ewes kept with control rams stopped ovulating for some time; consequently, those ewes had a longer anovulation period than did the group exposed to treated rams (3 ± 3 vs. 18 ± 7 days, respectively; P < 0.05). In conclusion, continuous exposure to sexually activated rams induced by artificial photoperiod and melatonin implants in spring extended the ovarian activity of ewes in spring, which results in an increase in estrous expression.

PROSTAGLANDIN VERSUS PROGESTAGEN PROTOCOLS IN OESTRUS SYNCHRONIZATION IN THE YANKASA EWE

This study was conducted to compare the effects of prostaglandins (estroPLAN® and Lutalyse®) and progestagens (CIDR® and FGA-45®) in synchronizing oestrus in Yankasa ewes between January and February 2014. Thirty three (33) Yankasa ewes aged 1.5- 3 years, 21 to 26 kg body weights, with body condition score of 2.5- 3.5 were used in this study. Ewes were randomly allocated into 5 groups, Group 1 (ewes treated with Lutalyse® [YK-LT], n= 7), Group 2 (ewes treated with estroPLAN® [YK-ET], n= 7), Group 3 (ewes treated with EAZI- BREED™ CIDR® [YK-CD], n= 5), Group 4 (ewes treated with Fluorogestone acetate-45® [YK-FG], n= 7) and Group 5 (Control [YK-CT], n= 7). Natural breeding was carried out using sexually active rams for 5 days following progestagen withdrawal and second prostaglandin administration. 100% oestrus response was observed in YK-ET, YK-CD and YK-FG, respectively. Time to onset of oestrus was 68.23 ± 17.28 h in YK-LT, 49.29 ± 4.5 h in YK-ET, 33.48 ± 8.6 in YK-CD, 53.27 ± 12.3 in YK-FG and 39.2 ± 13 in YK-CT. Duration of oestrus was longest in YK-LT (51.35 ± 13.9 h) and shortest in YK-CT (17.2 ± 6.9 h). Mounts per oestrus period was highest in YK-CT (26.9 ± 4.8) and lowest in YK-ET (14.3 ± 4.3). Conception rate was 100% in the YK-LT, YK-ET, YK-CD groups respectively. It is concluded that estroPLAN® and CIDR® offered the best results in synchronizing oestrus in Yankasa ewes and may be used by farmers to enhance productivity.

Genetic diversity in Kermani sheep assessed from pedigree analysis

Genetic diversity in Kermani sheep was assessed using the pedigree records by quantifying demographic parameters under pedigree analysis via studbook information collected from 1990 to 2011 in the breeding station of Kermani sheep, Sharebabak, south-east of Iran. Lambs born during 2008–2011 were considered as reference population. The mean generation interval from four pathways was 4.48 years. The generation interval in sire-progeny pathway was longer than dam-progeny. Mean inbreeding and average coancestry for reference population were computed as 0.51% and 1.04%, respectively. Average equivalent complete generation, as a measure of pedigree completeness, was 2.22. Effective population size was estimated to be 100 from the individual rate in coancestry and 120 from the individual increase in inbreeding. Genealogical parameters estimated based on probabilities of gene origin including the effective number of founders, the effective number of ancestors, the effective number of founder genomes (founder genome equivalents) and the effective number of non-founder genomes for reference population were estimated as 149, 72, 48 and 71, respectively. Approximately, 50% of total genetic variation was explained by the 33 most influential ancestors, with a maximum individual contribution of 4.8%. The average relationship coefficient among active rams and the average relationship coefficient between active rams and ewes during the last 4 years (2008–2011) were 0.11 and 0.05, respectively. The results indicated that although some evidences on bottlenecks and genetic drift during recent years were identified in the studied population, a relatively considerable genetic variability exists in this population.

Early sexual experience and stressful conditions affect the response of young ewes to the male

Exposure of anoestrous ewes to rams induces oestrous cycles (the ‘ram effect’). This response is poor in young-sexually naive females, possibly because they lack sexual experience and are sensitive to stress. Firstly, we assessed the conditions required for the acquisition of sexual experience. We exposed naive females at 5 or 9 months of age to rams and subsequently assessed their response at 1 year of age, to the ram effect. Unexpectedly, 2 weeks pre-exposure at 5 months and under some conditions at 9 months, inhibited the ram effect at 1 year of age, suggesting that early contact with rams was stressful and had long-term negative effects on reproduction. Consequently, we assessed the combined effect of stress and sexual experience on responses to the ram effect. At 9 months of age, we pre-exposed naive females using sexually active rams to achieve ‘positive’ (voluntary contact) or ‘negative’ (forced contact) experiences, and assessed responses to the ram effect at a year of age. In parallel, we subjected naive females to stressful conditions at the time of the male effect. During pre-exposure, females with ‘negative’ contact exhibited more vigilance and stress cues and had higher levels of cortisol than ‘positive’ contact ewes. Regardless of pre-exposure or stress, the response to the ram effect at a year of age was inhibited. These experiments confirm that contact with sexual partners can be stressful to young ewes and highlight the need to consider their emotional state when conditioning them to the presence of rams and when managing breeding programs.

Evaluation of three-ram cohort serving capacity tests as a substitute for individual serving capacity tests1,2

Alternatives to time-consuming, laborious individual serving capacity tests (ISCT) are needed to classify ram sexual behavior. The objective of study 1 was to evaluate the relationship between the first 3-ram cohort test (COSCT) scores and the mean of 5 ISCT scores. The objective of study 2 was to determine whether 1 or 2 additional COSCT improved the ability to predict ISCT scores. For study 1, rams (n = 69) were assigned to either a COSCT given before or after 9 ISCT. For study 2, rams (n = 127) were given 3 COSCT before or after 6 ISCT. For repeated COSCT, rams were initially grouped at random and subsequently rerandomized so that each ram was grouped with at least 1 different ram for each test. For both studies, the number of ejaculations from COSCT was compared with the mean number of ejaculations across the second through sixth ISCT. A threshold between high- and low-performing rams was defined in each analysis as the mean ISCT scores of sexually active rams. Rams with a mean number of ejaculations in ISCT greater than the threshold were classified as having high sexual activity, whereas rams below the threshold were classified as having low sexual activity. Rams with no ejaculations in ISCT were classified as sexually inactive. Data from studies 1 and 2 were used to evaluate the relationship between the first COSCT and the mean of 5 ISCT scores. Data from multiple COSCT were fit to various models to determine whether the ability to predict ISCT scores was improved with 1 or 2 additional COSCT. The best model for ISCT and COSCT was a piecewise linear regression model. The first COSCT correctly identified all sexually inactive rams in both studies. The first COSCT, however, also classified 56% of low sexually active rams and 18% of high sexually active rams as inactive. Rams had a 71% probability of high sexual activity in ISCT if they were classified as sexually active in the first COSCT. We conclude that a single COSCT is a reliable, albeit more conservative, and efficient alternative to a series of ISCT for characterizing sexual activity of rams. Multiple COSCT can provide some protection against culling rams with high sexual activity (i.e., approximately 50% less with 2 additional COSCT) and still retain most of the efficiency compared with ISCT. It is important to use high-performance rams for breeding because they will approximately double the number of ewes bred and lambs sired compared with low-performance rams if a large number of ewes need to be serviced daily.