Influence of sexually inactive bucks subjected to long photoperiod or testosterone on the induction of estrus in anovulatory goats (original) (raw)
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Journal of Animal Science, 2002
Two experiments were conducted to determine the response of Creole male goats treated with long days and melatonin implants, and the response of the anovulatory does to male effect using males treated only with artificially long days. All animals were allocated to open sheds. In Exp. 1, one group of males was under natural photoperiod (CG; n = 7); the second group was submitted to 2.5 mo of long days followed by the insertion of two s.c. melatonin implants (LD+MEL; n = 7); the third group was subjected only to 2.5 mo of long days (LD; n = 7). Testicular weight was measured every 2 wk. Plasma testosterone concentrations were determined weekly. A treatment × time interaction was detected (P < 0.001) for testicular weight and plasma testosterone concentration. In the LD+MEL and LD groups, testicular size and plasma testosterone levels varied in a similar way, but differed from those observed in CG (P < 0.001). In this latter group, testicular weight displayed seasonal variations and peaked in June, whereas in treated groups this peak occurred in March. In CG, testosterone varied in a seasonal manner and plasma concentrations increased in June and re
Small Ruminant Research, 2015
The possible effect of testosterone administration and the male-to-female ratio regarding the male sexual behavior during the resting season and the out-of-season reproductive performance of anestrous goats exposed to the male effect under subtropical conditions (26 • N) was evaluated. In the experiment-1 two treatments were considered (1) Testosterone-treated bucks (TTB; n = 4; 25 mg, i.m., testosterone, every 3-days × 3-week), and (2) Non-testosterone treated bucks (NTTB; n = 4; i.m. saline every 3-days × 3week). Thereafter, both experimental groups were exposed to adult goats over two days (1 h × 2days) and two sexual behavior tests were performed: appetitive sexual behavior (ASB) and consummatory sexual behavior (CSB). In the experiment-2, multiparous lactating and anoestrous crossbred goats (n = 60) were randomly assigned to one of four treatments with different male-to-female ratios (MFR): (1) High MFR goats [HMFR; n = 20, 1:10 ratio], (2) Low MFR [LMFR; n = 10, 1:5 ratio] each group exposed to two NTTB, (3) High MFR goats [HMFR + T; n = 20, 1:10 ratio], and (4) Low MFR [LMFR + T; n = 10, 1:5 ratio] each group exposed to two TTB. While the TTB displayed higher ASB (p < 0.01; 91.9% vs 8.1 %), the NTTB did not express neither CSB (p > 0.05; 100% vs 0%) nor sexual behavior irrespectively of the male-to-female load. The HMFR + T depicted a higher ASB (p < 0.01; 65% vs 35%) than the LMFR + T, without differences in CSB between HMFR + T and LMFR + T. Also, TTB induced estrus response (86.6%) and pregnancy rate (83.3%) while NTTB did not. Neither estrus response (85 vs 90%) nor pregnancy rate (85 vs 80%) differed between the HMFR + T and LMFR + T groups. Exposing of anestrous goats to testosterone-treated bucks, irrespective of mating load, was able to successfully invoke neurophysiological pathways to activate ovarian function and to promote a uterine milieu prone to the establishment of pregnancy during the anoestrus season.
Small Ruminant Research, 1996
Two hundred and ten Criollo crossbred goats under extensive conditions were randomly allotted to treatments to measure effects of exposure to intact bucks (6 >, androgenized wethers (W) or androgenized does ( Q >, during the breeding season (November), on estrus response. Castrated bucks were androgenized by injecting 60 mg of testosterone propionate every 3 days for 20 days and every 4 days during the teasing period. Does were given 300 mg of testosterone during 2 consecutive days, additional 300 mg on Day 5 and 60 mg every 4 days. After 13 days of stimulus, induction of esttus did not vary among teasers (87.1, 94.3 and 84.0% for 8, W and Q , respectively) but time to onset of estrus was significantly shorter (P < 0.01) for goats exposed to 8 (4.6 & 0.40 days) compared with goats exposed to W (6.9 + 0.39 days) and Q (8.1 f 0.46 days). In another experiment conducted during the non-breeding season (April) a total of 150 goats were divided into two groups and exposed either to c? or W. After 37 days of teasing the proportion of does exhibiting behavioral estrus was half of that observed during the breeding season. There was no significant effect of teasers on estrus response (46.7 and 51.7% for c? and W, respectively) but the time to onset of estrus was shorter for d (27.3 f 0.66) compared with W (30.7 + 1.26). Results of a third experiment showed that pregnancy rate (76.5% vs 24.7%) and prolificacy (1.61 + 0.04 vs 1.25 + 0.08) was affected (P < 0.01) by month of breeding (January vs April). Results demonstrate that androgenized wethers and testosterone-treated does can be used successfully to induce estrus during the breeding season of goats, but that, under these conditions, only half of the does respond to this teasing during the non-breeding season, which leads to poor reproductive performance when goats were exposed to bucks during the non-responsive anovulatory period.
Domestic Animal Endocrinology, 2014
The response of male goats exposed to different durations of long days (LD) during an extra-light treatment in autumn-winter, and their ability to induce ovulations in seasonally anovulatory goats were investigated in 2 experiments. In experiment 1, control males were exposed to natural photoperiod (n ¼ 5), whereas 4 additional groups (n ¼ 5/group) were exposed to 16 h of light per d during 75, 45, 30, or 15 d of LD. In the 4 groups, photoperiodic treatments ended on January 15th. Plasma concentrations of testosterone were determined in blood samples obtained once a week from October 15th to May 30th. The rise of testosterone levels occurred earlier in males from the 75-LD and 45-LD groups than in those from the 30-LD, 15-LD, and control groups (P < 0.05). In addition, the time during which levels of testosterone remained >5 ng/mL was longer in males from the 75-LD and 45-LD than in those from the 30-LD and 15-LD groups (P < 0.05). In experiment 2, a group of anovulatory goats (n ¼ 13) was isolated from males, while 3 additional groups were put in contact during 15 d with males previously exposed to 75, 45, or 30 days of LD (n ¼ 25, 27, and 26 females/group, respectively and n ¼ 3 males per group). The proportion of goats that ovulated was higher in the 3 groups in contact with the photo-stimulated males (range: 88%-92%) than in the group isolated from them (0%; P < 0.05). The proportion of pregnant females did not differ between the 3 groups of does in contact with photo-stimulated males (range: 78%-92%; P > 0.05). We conclude that, in our experimental conditions, a photoperiodic treatment as short as 30 d of LD during autumn-winter, stimulated testosterone secretion of bucks during their period of sexual rest and rendered them able to induce ovulations in seasonal anestrous goats and to obtain pregnancies in these females.
Estrus induction in anestrous mixed-breed goats using the “female-to-female effect”
Tropical Animal Health and Production, 2013
A trial was conducted during the anestrous period in female goats to determine: (a) whether estrus can be induced in anestrous goats by administration of equine chorionic gonadotropic hormone (eCG) and PGF 2α under pen conditions and (b) whether these sexually active female goats can elicit sexual arousal in sexually inactive bucks. One hundred and fifteen pluriparous, nonlactating mixed-breed female goats were randomly assigned to one of four treatment groups: (1) administration of a single dose of 240 IU of eCG, 50 μg PGF 2α i.m., and 25 mg progesterone (P 4 ) (eCG; n030);
Tropical Animal Health and Production
This study was conducted to determine whether flushing or the stimulus of estrogenized goats is necessary to achieve a high reproductive response in anestrous goats on rangeland. Does were feed-supplemented on rangeland (flushed, n = 20). Other group was exposed to estrogenized does during the mating period (stimulated, n = 20). A third group was both supplemented and stimulated (stimulated–flushed, n = 20) and other group grazed on rangeland only (control, n = 18). More goats in the stimulated and stimulated–flushed groups showed estrus during the first 5 days of joining (45% and 60%, respectively) than the control and flushed groups (11% and 5%, respectively; P P
Theriogenology, 2014
The present study was carried out to determine whether the presence of photostimulated sedated male goats could stimulate the LH preovulatory surge and ovulation in seasonal anestrous goats. Sexually experienced male goats were treated with artificial long days (16 hours light per day) from 1 November to 15 January to stimulate their sexual activity in March and April, corresponding to the natural sexual rest. A female group of goats (n ¼ 20) was exposed to non-sedated males who displayed an intense sexual behavior and provided strong odor (non-sedated group). Another female group of goats (n ¼ 20) was exposed to the photo-stimulated male goats, but these males were sedated with Xylazine 2% to prevent the expression of sexual behavior (sedated group). The sedated males also provided a strong odor. Females of both groups had full physical and visual contact with non-sedated or sedated males. In both groups, the males remained with females during 4 days. The LH preovulatory surge of 10 female goats per group was measured by determination of LH plasma concentrations in samples taken every 3 hours. In addition, in all goats, (n ¼ 20 by group), ovulation was determined by measuring plasma concentrations of progesterone. The proportion of female goats showing a preovulatory LH surge was higher in goats exposed to non-sedated (10/10) than in those exposed to sedated bucks (0/10; P < 0.0001). Similarly, most of does in contact with non-sedated males ovulated (19/20), but none of those in contact with sedated males did so (0/20; P < 0.0001). We conclude that the expression of an intense sexual behavior by male goats is necessary to induce LH preovulatory surge and ovulation in seasonally anovulatory goats.
Theriogenology, 2016
The objectives of the present study were to assess the effect of permanent contact of teasers without copulation on the interval from controlled internal drug release (CIDR) removal to estrus onset, estrus duration, ovulation time, number of ovulations, and interval from CIDR removal to ovulation time on estrus-synchronized Boer goats. During the fall season, a controlled randomized design experiment with two groups, control (CON; n ¼ 18) and treatment (TRE; n ¼ 18), was performed. The TRE group was maintained permanently in a pen with an aproned buck immediately after CIDR removal. The CON group was maintained in a different pen without permanent exposure to the male. All females were estrus synchronized with CIDR maintained in the vagina for 7 days and received 50 mg of GnRH im at device insertion and 5 mg of natural prostaglandin F-2a at device removal. Females were considered to be in estrus when they accepted mounting by the aproned bucks. Estrus was detected four times a day after CIDR removal (at 6 AM, 12 noon, 6 PM, and 12 midnight) using bucks with canvas apron as teasers. The ovulation time and number of ovulations were assessed by transrectal ultrasonography starting 24 hours after estrus onset and repeated every 6 hours until complete ovulation was detected. The estrus onset for the CON group was 44.0 AE 8.3 hours and for the TRE group, it was 37.0 AE 7.7 hours (P ¼ 0.01). Estrus duration from the CON group was 43.7 AE 9.2 hours and for the TRE group, it was 38.3 AE 6.6 hours (P ¼ 0.05). The first, last, and mean ovulation times for the CON group were 32.4 AE 5.3, 38.4 AE 3.4, and 35.4 AE 3.9 hours, and for the TRE group, the times were 31.8 AE 2.8, 36.7 AE 3.0, and 35.8 AE 3.6 hours, respectively (P ¼ 0.85, P ¼ 0.23, and P ¼ 0.82, respectively). The number of ovulations for the CON and TRE groups was 2.6 AE 0.7 and 2.6 AE 0.6 ovulations, respectively (P ¼ 0.96). The interval time for CIDR removal to ovulation for the CON group was 79.2 AE 8.2 hours and for the TRE group, the interval time was 73.2 AE 6.2 hours (P ¼ 0.05). It was concluded that the permanent presence of male without copulation with estrus-synchronized does hastened estrus onset, reduced estrus duration, and decreased the interval time from CIDR removal to ovulation without modification of ovulation time and number of ovulations in Boer goats.
de Revisión MALE EFFECT : SUSTAINABILITY AND EFFECTIVENESS IN INDUCING ESTRUS IN GOATS EFECTO MACHO
2016
The male effect is a strategy used in reproductive management of herds for the induction and synchronization of estrus, consisting of the reintroduction of males into a group of previously separated females. This interaction induces an increase in LH pulses followed by ovulation. In all species, there are communication mechanisms, many involving the use of chemoreceptor organs that enable the perception of pheromones, mediators in intraspecies interaction related to recognition for mating. Synchronization of female estrus by the male effect has many advantages reported by several authors, such as the reduction of costs, the absence of undesirable immune response by the use of chorionic gonadotropin, the decrease of hormonal residues in treated females, thus complying with ecological and sustainable production principles in animal production.