No previous isolation of female goats is required for novel males to induce a male effect, especially if direct physical contact is established.

Goat does supposedly need to be separated from bucks before male stimuli can induce reproductive activity, ovulation, and estrous. The present study examined the reproductive response (ovulation and estrous) of does to "novel" bucks in direct contact with them and when separated from them by a fence. One hundred fourteen does were distributed into three groups: (1) ISOL group (N = 31): females that had been completely isolated from males for 46 days, and thereafter placed in direct contact with "novel" males during the breeding period; (2) NOTISOL-CONTACT group (N = 29): females that had been in contact with "familiar" vasectomized males for 46 days and thereafter placed in direct contact with novel males during the breeding period; (3) NOTISOL-NO CONTACT group (N = 54): females that were in contact with familiar vasectomized males for 46 days and thereafter introduced to novel males, but separated by a fence, during the breeding period. All the males were treated with melatonin to ensure that they were sexually active. Estrous activity was recorded daily by direct visual observation of the marks left by marking harnesses worn by the males. Ovulation was confirmed via the plasma progesterone concentration (measured in weekly blood samples). The ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy, and productivity were also determined for the ISOL and NOTISOL-CONTACT groups (naturally, in the NOTISOL-NO CONTACT group, no pregnancies were possible). The introduction of novel males induced the same ovarian response in each group (P > 0.05), but the percentage of females that showed estrous and ovulation was lower in the NOTISOL-NO CONTACT group (P < 0.05). No differences were seen between the ISOL and NOTISOL-CONTACT groups (P > 0.05) in terms of fecundity, fertility, prolificacy, and productivity. These results show that the introduction of novel males to females already in contact with familiar males induces ovarian activity similar to that observed in the classical male effect (ISOL group) and that this response leads to a significantly higher estrus activity only when direct physical contact between the females and the novel males is established.

The timing of oestrus, the preovulatory LH surge and ovulation in Blanca Andaluza goats synchronised by intravaginal progestagen sponge treatment is modified by season but not by body condition score.

The aim of this study was to determine whether a seasonal pattern of reproductive events is followed after synchronisation by intravaginal progestagen sponge treatment in female Blanca Andaluza goats, and whether the timing of these events is affected by body condition score (BCS). During seasonal anoestrus (March), and again during the breeding season (November), the same 32 does were distributed into four subgroups according to their BCS: ≤2.25, =2.50, =2.75, and ≥3.00 (n=8 in all cases). They were then synchronised using a commercial intravaginal sponge treatment. Every 4h over the 72h following sponge removal, oestrous activity, the LH concentration and each doe's number of follicles were followed by transrectal ultrasonography. The does synchronised during seasonal anoestrus produced more follicles than those synchronised during the breeding season (P<0.01). The time elapsed between sponge removal and the onset of oestrus, the LH surge and time of ovulation, was also shorter in these does (P<0.001). The BCS only modified the number of follicles present in the ovary just before ovulation; this number was significantly lower in the =2.50 BCS subgroup than in the other subgroups (P<0.05). The present results show that the time to ovulation, and all events around it, are modified by the season in which Blanca Andaluza does are synchronised, but not by BCS.

Influence of the male effect on the reproductive performance of female Payoya goats implanted with melatonin at the winter solstice.

This research addressed the effect on reproductive performance of melatonin implants inserted at the winter solstice in Payoya goats. Female goats (n = 100) were divided into two experimental groups, one subjected and the other not subjected to the male effect. Half of each group was implanted with melatonin at the winter solstice; the remaining animals received no such hormone treatment. Oestrous activity, as detected by visual observation, was recorded daily using melatonin implanted bucks. Trans-rectal ultrasonography was used to estimate of time of ovulation. Corpus luteum activity was confirmed by plasma concentrations of progesterone greater than 0.5 ng/mL. Fecundity, fertility, prolificacy and productivity were calculated. Neither the male effect nor melatonin treatment alone influenced reproductive performance. The greater fecundity and fertility: 91.7% (P < 0.05) was obtained with melatonin implantation plus the male effect. Greater productivity occurred when melatonin was used (1.02 ± 0.10 compared with 0.76 ± 0.66 mean number of kids per female for melatonin and non-melatonin treated groups, respectively, P < 0.05). The present results show that the fertility of female Payoya goats implanted with melatonin at the winter solstice can be improved by subjecting females to the male effect. Moreover, productivity of does is enhanced when melatonin implants are used in comparison to productivity of non-treated females.

Reproductive performance is improved during seasonal anoestrus when female and male Murciano-Granadina goats receive melatonin implants and in Payoya goats when females are thus treated.

This work investigates whether the reproductive performance of Mediterranean goats achieved using melatonin implants at around the spring equinox is affected by the protocol followed, i.e. implanting females only, males only, both sexes or neither sex. In a first experiment, Murciano-Granadina females (n = 419, 510 and 631 for three consecutive years) were divided into four groups: treated with melatonin (FM) and not treated with melatonin (FC), mounted by males treated with melatonin (MM) or not (MC). In a second experiment, performed during 2009, the same protocols were used with 635 Payoya females and the results compared with those obtained for the same year for the Murciano-Granadina breed. Fertility (percentage of goats kidding), litter size (number of kids born per female kidded) and productivity (number of kids per female in each mating group) were calculated. In the first experiment, better reproductive performances were obtained when females (overall fertility: 71.1% vs 57.0% for the FM and FC animals; productivity 1.37 ± 0.04 kids per female vs 1.12 ± 0.03 kids per female for the FM and FC animals; p < 0.01) or males (overall fertility: 65.9% vs 58.4 for the MM and MC animals; productivity 1.28 ± 0.03 kids per female vs 1.13 ± 0.04 kids per female for MM and MC groups, respectively; p < 0.01) were implanted with melatonin. Moreover, the interaction sex × melatonin treatment had a significant effect (p < 0.05) on productivity. In the second experiment, for the Murciano-Granadina breed, the greatest increase in the number of kids born per female was obtained when the females were treated with melatonin, in either the FM/MC or FM/MM protocols (0.54 extra kids and 0.53 extra kids per female, respectively) (p < 0.01). In the Payoya breed, the greatest increase was obtained using the FM/MC protocol (0.19 extra kids per female). Thus, improved reproductive performances are obtained when female Murciano-Granadina and Payoya goats are implanted with melatonin, although important differences in reproductive performance are seen between the breeds.

The response of luteinizing hormone secretion to photoperiod is modified by the level of nutrition in female Mediterranean goats.

This paper reports the influence of nutrition on the photoperiodic control of luteinizing hormone (LH) secretion in female Mediterranean goats (i.e., goats from the Mediterranean area in general). Ovariectomized, oestradiol-treated goats were subjected to two consecutive intervals of 3 months of long days followed by 3 months of short days (group LDSD, N=20), or vice versa (group SDLD, N=20). The LDSD and SDLD does were also randomly assigned to one of two nutrition groups that received either 1.1 (H group, N=10) or 0.7 (L group, N=10) times their maintenance requirements. Live weight and body condition score were determined weekly and LH concentrations twice per week. To establish the pulsatility of secretion of LH, three periods of intensive sampling were undertaken. Melatonin was determined after a period of 45 short or long days. All photoperiod/nutrition groups showed large variations in LH concentrations according to photoperiod, with nutrition having a significant effect (P<0.001). The mean time between the shift from long to short days and the stimulation of LH secretion, and between the shift from short to long days and the inhibition of LH secretion, was different in each nutrition group (at least P<0.05). No differences were seen in the frequency of LH pulses between the nutrition groups, but differences between sampling periods were observed (P<0.001). Melatonin secretion was not affected by food supply. These results confirm: (1) that Mediterranean female goats are sensitive to photoperiod, (2) that this environmental cue may control the timing of pituitary activity under natural conditions, and (3) suggest that nutrition plays an important role in the effect of photoperiod on LH secretion.

Artificial long days and daily contact with bucks induce ovarian but not oestrous activity during the non-breeding season in Mediterranean goat females.

The aim of the present study was to determine whether a treatment of 3 mo of artificial long days and daily contact with bucks can stimulate reproductive activity during the normal seasonal anoestrous in female goats, and whether such treatment modifies the onset of the normal breeding season. Thirty-nine adult, open does were assigned to two treatments of similar mean body weight (BW) and body condition score (BCS). One treatment (LD; n=18) was housed in a light-proof building and exposed to long days (16 h of light/d) from 17 November to 5 February, and then exposed to the natural photoperiod in an open shed. The remaining females were housed in an open shed under natural photoperiod conditions throughout the experiment (control [C]; n=21). Plasma samples for progesterone, BW and BCS were recorded every wk. Oestrous activity was checked daily using aproned bucks. Bucks were housed close to females in a separate barn from the onset of the experiment. Ovulation rate was determined by laparoscopy 7 d after positive identification of oestrus. The interaction of treatment by time for temporal concentrations patterns of progesterone concentrations indicated that luteal activity in LD does were greater (P<0.001) than those of C does during the natural seasonal anoestrous season. None of the C does exhibited oestrous or luteal activity during the non-breeding season; whereas, 72% of LD does exhibited luteal activity only 33% of them showed oestrous activity and during this season (P<0.01). Differences in resumption of the oestrous or luteal activity were not observed (P>0.05) in the subsequent breeding season between treatments. In conclusion, 3 mo of exposing does to long days and daily contact with bucks during the breeding season appears to stimulate reproductive processes that normal would not occur during the anoestrous season. However, this treatment does not induce oestrus is adequate numbers of does to be of practical value. Finally, this treatment does not modify the onset of the subsequent natural breeding season.

Artificial long days in addition to exogenous melatonin and daily contact with bucks stimulate the ovarian and oestrous activity in Mediterranean goat females.

One experiment was conducted to determine whether the treatment with artificial long days and exogenous melatonin can induce reproductive activity during spring (seasonal anoestrus) in Mediterranean goats that are in daily contact with bucks and whether this treatment causes a variation in the reactivation of the reproductive activity in the normal breeding season. The experiment started on 4 November 2005 and finished on 27 October 2006. Thirty-four adult and barren does were used, distributed into two groups balanced according to their live weight (LW) and body condition score (BCS). Seventeen females were exposed to long days (16 h of light/day) from 14 November 2005 to 20 February 2006. On 20 February, they received one s.c. melatonin implant (LD-M group) and were exposed to natural photoperiodic changes in an open shed. The other females during the experiment were placed in an open shed under natural photoperiod and remained as the control group (C group). The C and LD-M groups were keeping in contact with males during the whole experiment. During the experiment, the LW, BCS and plasma progesterone concentrations were measured weekly, oestrous activity was tested daily using entire aproned bucks, and ovulation rate was evaluated by laparoscopy 7 days after positive identification of the oestrus. A clear treatment-time interaction was observed for plasma progesterone concentrations (P < 0.001), with a period of high progesterone concentrations during the natural seasonal anoestrus in the LD-M group. Although 94.1% of females in the LD-M group presented ovarian activity during this period, no female in group C did. Resumption of ovarian activity in the subsequent natural breeding season was 2 weeks later in the LD-M group in comparison with group C (P < 0.05). We can conclude that in Mediterranean goat breeding systems, when females are in daily contact with bucks, the treatment with 3 months of long days and melatonin implant at the end of the light photoperiodic treatment can induce ovarian and oestrous activity during the seasonal anoestrus. Finally, this treatment causes a short delay in the subsequent reactivation of ovarian activity in the natural breeding season.

Melatonin concentrations in the two jugular veins, and relationship with the seasonal reproductive activity in goats.

The authors investigated whether melatonin concentrations vary between the two jugular veins and whether absolute (nocturnal) or relative (nocturnal/diurnal ratio) plasma melatonin concentrations are associated with seasonal reproductive activity measured by oestrus or ovulatory activity in Payoya goats. Thirty-two adult Payoya goats were penned under natural photoperiod. Oestrus activity was tested daily using aproned males-twice a week plasma was sampled for progesterone. Melatonin plasma concentrations were studied at each equinox and solstice of the year in jugular samples taken simultaneously by venipuncture. Nocturnal and diurnal plasma melatonin concentrations from each jugular vein were assessed in 3 and 2 plasma samples per goat, respectively, taken at hourly intervals in each period. No differences in melatonin concentrations between the two veins were observed, but there was a significant interaction (P < 0.001) between jugular vein and animal in nocturnal melatonin concentrations. There was no effect of sampling period on melatonin concentrations and the coefficient of correlation between sampling periods was very high. The analyses performed indicated that neither absolute nor relative melatonin concentrations were related with the dates of onset or end of ovulatory/oestrus activity. Therefore, we concluded that in goats (1) melatonin concentrations are highly variable between jugular veins in the same individual but not in the general population, (2) melatonin concentrations are highly repeatable for each individual, and (3) absolute and relative amplitudes of melatonin concentrations are not linked to the seasonal breeding activity in Mediterranean goats.

Effect of melatonin implants on sexual activity in Mediterranean goat females without separation from males.

This work was designed to determine whether melatonin treatment at the spring equinox can induce reproductive activity in goats without separation from males (separation being the normal practice in Spanish farming systems) and whether this treatment modifies the onset of the natural breeding season. Twenty-nine entire does were distributed into two groups (Group M, n=14; Group C, n=15). A third group of ovariectomized, estradiol-treated goats (OVX group, n=5) was used to study the effect of melatonin on reproductive activity. On March 18, Groups M and OVX received a subcutaneous melatonin implant. In entire females, estrus was tested daily using entire aproned males, and ovulation rate was assessed after identification of estrus. Plasma progesterone in entire goats, plasma luteinizing hormone (LH) in the OVX group, and live weight and body condition score for all animals were recorded once a week. In entire goats, a clear treatment by time interaction was observed for progesterone concentrations (P<0.001), with a period of high progesterone concentrations during the natural seasonal anestrus in Group M. A similar period of high LH concentrations was observed in the OVX group. Whereas all females of Group M presented ovarian activity during this period, no female of Group C did. The resumption of the natural breeding season was retarded in Group M in comparison with that in Group C (P<0.05). We can conclude that in Mediterranean goats, melatonin implants can induce reproductive activity without separation from males, and it causes a small retardation in the reactivation of reproductive activity in the natural breeding season.