ABSTRACT Some breeds of goats originating from or adapted to subtropical latitudes display season... more ABSTRACT Some breeds of goats originating from or adapted to subtropical latitudes display seasonal variations of their annual rhythm of reproduction. The reproductive seasonality causes a seasonal production of goat-derived products affecting producers, goats’ meat and milk industry and consumers. A good knowledge of the annual rhythm of reproduction, as well as the identification of the major environmental cues controlling this rhythm in both males and females, are necessary to draw new and sustainable techniques to induce a synchronized reproductive activity outside the natural breeding season and therefore to increase the out-of-season availability of the goat-derived products. This knowledge allows to control caprine reproduction without the use of exogenous hormones, and to develop techniques adapted to the environmental, economic and social characteristics of the breeding systems. Thus, in this review we will describe how photoperiodic treatments can be used to induce the sexual activity of male goats during the period of sexual rest. Then, we will describe how these photo-stimulated males were used to induce and synchronize the sexual activity of anestrous goats maintained in intensive or extensive management conditions by means of the male effect. In subtropical latitudes, the use of the male effect performed by using photo-stimulated bucks constitutes an original and sustainable way to control goats’ reproduction.
Sexually inexperienced rams display lower frequency of nudging, ano-genital sniffing, mounting at... more Sexually inexperienced rams display lower frequency of nudging, ano-genital sniffing, mounting attempts, and mounts with intromission than experienced ones. Experienced photo-stimulated males display high level of sexual behaviour. The aim of this study was to determine: i) whether sexually inexperienced photo-stimulated males display similar sexual behaviour as the experienced ones, and ii) whether these inexperienced bucks can stimulate sexual response in anoestrous goats, as the experienced ones. Sexually inexperienced and experienced photo-stimulated males (n ¼ 5 each) were used. In April, two groups of anovulatory females (n ¼ 50 each) were exposed to these males for 15 d. Male sexual behaviour was registered for three days, upon their introduction into female groups. On day 1, the inexperienced males displayed higher nudging than the experienced ones (p < .001), whereas on days 2 and 3, the experienced males displayed higher nudging than the inexperienced ones (p < .001). The ano-genital sniffing, mounting attempts, and mounts with intromission did not differ between the inexperienced and experienced groups (p > .05). The proportion of females ovulating did not differ between the two groups (!82 %; p ¼ 1.0). Pregnancy rate (!68 %; p ¼ .829) did not differ between the females exposed to inexperienced or experienced males. It is concluded that sexually inexperienced photo-stimulated males show similar sexual behaviour as the experienced ones, and they are able to induce sexual response in seasonally anoestrous goats through the male effect.
Journal of Animal Behaviour and Biometeorology, 2021
Sexually inexperienced ewes display lower estrous behavior during the first contact with rams. Th... more Sexually inexperienced ewes display lower estrous behavior during the first contact with rams. The objective of this study was to determine whether sexually inexperienced anestrous females display estrous behavior and ovulatory activity as the sexually experienced females, and with restricted sexual experience exposed to photo-stimulated bucks. Six bucks were rendered sexually active during the non-breeding season by exposure to artificially long days (16 h of light and 8 h of darkness per day) for 2.5 months. The first group, sexually experienced females (n = 10) had physical contact with two vasectomized bucks, and mating was allowed; the second group, with restricted sexual experience (n = 10) had contact with two vasectomized bucks through a wire-mesh fence and mating was prevented; the third group, sexually inexperienced females (n = 9) was totally isolated from bucks. At 14-month-old the females were exposed to photostimulated bucks for 15 days. The proportion of females that displayed estrous behavior, ovulations, short and normal ovulatory cycles, and pregnancy rates did not differ between sexually experienced, with restricted sexual experience, and sexually inexperienced (P > 0.05, in all variables). Similarly, the ovulation rate did not differ between the three groups of females (P > 0.05). However, the interval from introduction of the bucks to the first estrus was shorter in sexually inexperienced females (P < 0.05). Therefore, sexually inexperienced anestrous females displayed estrous behavior, ovulation, and pregnancy rate similar to those displayed by sexually experienced and with restricted sexual experience when exposed to photo-stimulated bucks through the male effect.
International Journal of Animal and Veterinary Advances, 2013
The objective of the present study was to determine the accuracy and the negative prediction valu... more The objective of the present study was to determine the accuracy and the negative prediction value of Pregnancy-Associated Glycoprotein (PAG) at 29 d post artificial insemination by ELISA. Blood serums of multiparous Holstein cows were used (n = 275). Pregnancy diagnosis was carried out by rectal palpation at 40 d and it was considered as reference test. Pregnancy results based on the PAG-ELISA and the pregnancy diagnosis at 40 d showed high concordance with a kappa value of 0.7. The accuracy test based on PAG-ELISA at 29 d post artificial insemination compared with pregnancy diagnosis by rectal palpation was 88%. The values of sensibility, specificity, positive prediction value, negative prediction value and positive and negative likelihood ratio were 96, 78, 83 and 95%, 4.5 and 0.0442, respectively. It is concluded that pregnancy diagnosis of PAG-ELISA is reliable and accurate at 29 d post artificial insemination. The PAG-ELISA's negative prediction value diminishes the number of days in subjecting cows diagnosed as nonpregnant to diverse strategies of hormonal synchronization protocols.
Some breed of goats originating or adapted to subtropical latitudes display large seasonal variat... more Some breed of goats originating or adapted to subtropical latitudes display large seasonal variations of their sexual and/or reproductive activity. This seasonality causes a seasonality of milk, cheese and meat production. To solve this problem it is necessary to have a deep knowledge of the annual sexual activity of animals and to identify the environmental factor controlling the timing of the annual reproductive cycle. In this review we will describe our approach to develop sustainable techniques to control reproductive activity in goats from subtropical Mexico: (1) The characteristics of the annual breeding season in both male and female goats were determined; (2) Photoperiod was identified as the major environmental factor controlling the timing of the annual breeding season; (3) Photoperiod treatments were used to stimulate the sexual activity of bucks during the non-breeding season; (4) Male goats rendered sexually active were used to induce and synchronize the estrous behavio...
This study was designed to determine whether any relationship exists between exposure to artifici... more This study was designed to determine whether any relationship exists between exposure to artificial long days, milk yield, maternal plasma insulin-like growth factor 1 (IGF-1) levels, and kid growth rate in goats. One group of lactating goats was maintained under naturally decreasing day length (control group; n = 19), while in another one, they were kept under artificial long days (LD group; n = 19). Milk yield was higher in goats from the LD group than that in the control group (P < 0.05). Maternal IGF-1 levels at day 57 of lactation were higher (P < 0.05) in goats from the LD group than the levels in the control group and were positively correlated with the total milk yields per goat at days 43 and 57 of lactation (r = 0.77 and r = 0.84, respectively; P < 0.01). Daily weight gain at week 4 was higher (P < 0.01) in kids from the LD group than that in kids from the control group and was correlated with total and average IGF-1 maternal levels (r = 0.60 and r = 0.60, P < 0.05). It was concluded that submitting lactating goats to artificial long days increases milk yield, plasma IGF-1 maternal levels and the growth rate of the kids.
SummaryThe objective of this study was to determine the genetic diversity of creole cattle in nor... more SummaryThe objective of this study was to determine the genetic diversity of creole cattle in northwestern Mexico using the BoLA-DRB3.2 locus of the Major Histocompatibility Complex (MHC). A total of 56 creole cattle were sampled from five communities; in the state of Chihuahua (Cerocahui, Guadalupe y Calvo and Cuauhtémoc) and in the state of Baja California Sur (La Paz and Mulegé). The BoLA-DRB3.2 locus was genotyped by PCR-RFLP assay. Thirty-nine alleles were identified, out of which 14 had not been previously reported. The average level of inbreeding in all populations analyzed wasFIS= 0.09 (P< 0.0001), but only two populations (Cerocahui and Guadalupe y Calvo) showed an excess of homozygotes (P< 0.05). The breed differentiation in all populations studied wasFSC= 0.068 (P< 0.0001). The smallest genetic distance was between La Paz and Mulegé (0.022); but Mulegé presented smaller distances (0.028–0.053) with the populations of La Paz (0.071–0.083) and with Chihuahua. Baja ...
The present study was carried out to determine whether the presence of photostimulated sedated ma... more 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.
Under temperate and subtropical latitudes, ewes and goats display a reproductive seasonal pattern... more Under temperate and subtropical latitudes, ewes and goats display a reproductive seasonal pattern and their sexual activity during the anestrous period can be stimulated and synchronized by the introduction of males in the group, which is called the "male effect". The response of females to the male effect in the middle of the anestrous season is weak or absent. This failure may be due to the inability of the female to respond to males, as a result of a refractoriness of the female to the male stimulus. But, it may also be due to a low quality stimulus provided by the male which is, as the females, in seasonal rest. We tested this latter hypothesis in seasonally inactive goats kept under subtropical conditions by comparing the use of males with their sexual behavior stimulated or not by photoperiodic treatments. Treated males were able to induce estrous activity of females during the whole anestrus season. We have also determined that previous separation of the males and continuous contact during teasing are not absolute requisites when active bucks are used. While odor from the male and its sexual behavior play a primary role in inducing ovulation, vocalizations appear to facilitate the display of the does' estrous. It remains to be determined to which extent these conclusions apply under temperate latitudes and with more seasonal breeds. goat / male effect / buck vocalizations / male odor / sexual behavior / photoperiodic treatment
The objective of the present study was to determine whether parity is a factor that influences th... more The objective of the present study was to determine whether parity is a factor that influences the estrous and ovulatory responses of female goats when they are stimulated by males that show increased sexual activity. To stimulate sexual activity, four adult male goats were subjected to photoperiodic treatment for 2.5 months comprising long days, with the treatment commencing on 1 November. On 14 April at 1,900 h, a group of multiparous females (n=21) and a group of 16 months-old nulliparous females (n=19) were exposed to four bucks (two per group) for 15 days. Throughout the study period, the estrous behavior of these female goats was detected twice on a daily basis. Ovulations of the female goats were determined by ecography on days 7 and 18 after exposure to males. The sexual behavior of males was recorded twice every day from 0800 to 0900 h and from 1730 to 1,830 h during the first 4 days after introduction in the pen of females. The total cumulative proportion of multiparous females that had ovulations (100%) and displayed estrous behavior (100%) during the 15 days of exposure to males did not differ (P&amp;amp;gt;0.05) from that of nulliparous females (100% and 95%, respectively). The interval between introduction of males and onset of estrous behavior did not differ (P&amp;amp;gt;0.05) between multiparous (1.9+/-0.1 days) and nulliparous (1.7+/-0.2 days) females. The proportion of females displaying a short estrous cycle was greater (P&amp;amp;lt;0.05) in multiparous (13/21, 62%) than in nulliparous (5/19, 26%) females. Duration of these shorter than typical estrous cycles did not differ (P&amp;amp;gt;0.05) between groups (multiparous: 5.2+/-0.3 days, nulliparous: 4.5+/-0.1 days). The number of anogenital sniffings was greater (P&amp;amp;lt;0.001) in males exposed to nulliparous than in those exposed to multiparous females. In contrast, the number of mounting attempts was greater (P&amp;amp;lt;0.01) in males that were introduced to multiparous than in those that were introduced to nulliparous does. The number of flehmen, nudging, self-marking with urine, and mounts was not different (P&amp;amp;gt;0.05) between males that were in contact with multiparous and nulliparous females. These results indicate that regardless of parity, female goats respond to male introduction if they are stimulated by males that were previously exposed to artificial long days to increase their sexual behavior.
How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative
We investigated whether live vocalizations emitted by bucks interacting with anestrous females st... more We investigated whether live vocalizations emitted by bucks interacting with anestrous females stimulate secretion of LH, estrous behavior and ovulation in anestrous goats. In experiment 1, bucks rendered sexually active by exposure to long days followed by natural photoperiod were exposed in a light-proof-building to five anestrous females. Buck vocalizations were reproduced through a microphone-amplifier-loudspeaker system to an open pen where one group of goats (n=6) was exposed for 10 days to these live vocalizations. Another group of females (n=6) was isolated from males and vocalizations. The proportion of goats displaying estrous behavior was significantly higher in females exposed to buck vocalizations than in females isolated from males. The proportion of goats that ovulated did not differ between the 2 groups (exposed to males versus isolated). In experiment 2, female goats that either had previous contact with males (n=7), or no previous contact with males (n=7) were exposed to live buck vocalizations, reproduced as described in experiment 1, for 5 days. The number and amplitude of LH pulses did not differ between groups before exposition to buck vocalizations. Five days of exposure to male vocalizations significantly increased LH pulsatility only in females that had previous contact with males, while LH pulse amplitude was not modified. We concluded that live buck vocalizations can stimulate estrous behavior and LH secretion in goats if they have had previous contact with bucks.
We investigated whether LH secretion, estrous behavior and fertility would differ between sexuall... more We investigated whether LH secretion, estrous behavior and fertility would differ between sexually inexperienced and experienced anestrous goats exposed to the males. Male goats were rendered sexually active during the reproductive rest season by exposure to 2.5 months of artificial long days. Two groups of anovulatory sexually inexperienced and sexually experienced does were exposed to males during 15 days (n = 20 per group). LH pulsatility was determined every 15 min from 4 h before to 8 h after introducing males (Day 0). Estrous behavior was recorded twice daily. Pregnancy rates were determined on Day 50. Fertility was determined at parturition. Male sexual behavior was registered on days 1 and 2 during 1 h. Before introducing the males, the number of LH pulses did not differ between groups. After introduction of the males, all females increased their LH pulsatility, but the number of pulses did not differ between sexually inexperienced and experienced goats. The proportion of females displaying estrous behavior with a high pregnancy rate and fertility did not differ between inexperienced and experienced goats. The sexual behavior of the males did not differ significantly between those interacting with sexually inexperienced or experienced goats. We conclude that goats can show substantial endocrine and reproductive responses to males, even in the absence of previous sexual experience, when sexually active bucks are used.
Fernández, I.G., Salgado, R.H. and Vázquez, C.A.E. 2010. Two 250 mg doses of bovine somatotropin ... more Fernández, I.G., Salgado, R.H. and Vázquez, C.A.E. 2010. Two 250 mg doses of bovine somatotropin increase conception rate, IGF-I plasma concentration and reduce the days to estrus in Holstein cows following estrus synchronization. J. Appl. Anim. Res., 37: 101–104.To determine whether the administration of two low doses of recombinant bovine somatotropin (bST, 250 mg each) improves conception rate in Holstein cows when using a. protocol of estrus synchronization 266 multiparous, postpartum first service Holstein cows were used. Control cows (CON; n=158) were injected with placebo and bST cows (TRT; n=108) received two doses of 250 mg of bST on d 56 and 67±2 d (at the time of AI). Insulin-like growth factor-I plasma concentration was higher in TRT cows (d 58; P<0.01 and d 62; P<0.05) and conception rate was also higher in TRT cows (P<0.05). Days to estrus in TRT cows were shorter (62.2±0.8 vs 74.1±0.9; P<0.01). Milk production was higher in TRT cows (58 to 63 d; P<0.05). The results indicated beneficial effect of bST given in two divided doses in respect of conception rate, insulin-like growth factor-I plasma concentration and days to estrus in postpartum lactating dairy cows.
ABSTRACT Some breeds of goats originating from or adapted to subtropical latitudes display season... more ABSTRACT Some breeds of goats originating from or adapted to subtropical latitudes display seasonal variations of their annual rhythm of reproduction. The reproductive seasonality causes a seasonal production of goat-derived products affecting producers, goats’ meat and milk industry and consumers. A good knowledge of the annual rhythm of reproduction, as well as the identification of the major environmental cues controlling this rhythm in both males and females, are necessary to draw new and sustainable techniques to induce a synchronized reproductive activity outside the natural breeding season and therefore to increase the out-of-season availability of the goat-derived products. This knowledge allows to control caprine reproduction without the use of exogenous hormones, and to develop techniques adapted to the environmental, economic and social characteristics of the breeding systems. Thus, in this review we will describe how photoperiodic treatments can be used to induce the sexual activity of male goats during the period of sexual rest. Then, we will describe how these photo-stimulated males were used to induce and synchronize the sexual activity of anestrous goats maintained in intensive or extensive management conditions by means of the male effect. In subtropical latitudes, the use of the male effect performed by using photo-stimulated bucks constitutes an original and sustainable way to control goats’ reproduction.
Sexually inexperienced rams display lower frequency of nudging, ano-genital sniffing, mounting at... more Sexually inexperienced rams display lower frequency of nudging, ano-genital sniffing, mounting attempts, and mounts with intromission than experienced ones. Experienced photo-stimulated males display high level of sexual behaviour. The aim of this study was to determine: i) whether sexually inexperienced photo-stimulated males display similar sexual behaviour as the experienced ones, and ii) whether these inexperienced bucks can stimulate sexual response in anoestrous goats, as the experienced ones. Sexually inexperienced and experienced photo-stimulated males (n ¼ 5 each) were used. In April, two groups of anovulatory females (n ¼ 50 each) were exposed to these males for 15 d. Male sexual behaviour was registered for three days, upon their introduction into female groups. On day 1, the inexperienced males displayed higher nudging than the experienced ones (p < .001), whereas on days 2 and 3, the experienced males displayed higher nudging than the inexperienced ones (p < .001). The ano-genital sniffing, mounting attempts, and mounts with intromission did not differ between the inexperienced and experienced groups (p > .05). The proportion of females ovulating did not differ between the two groups (!82 %; p ¼ 1.0). Pregnancy rate (!68 %; p ¼ .829) did not differ between the females exposed to inexperienced or experienced males. It is concluded that sexually inexperienced photo-stimulated males show similar sexual behaviour as the experienced ones, and they are able to induce sexual response in seasonally anoestrous goats through the male effect.
Journal of Animal Behaviour and Biometeorology, 2021
Sexually inexperienced ewes display lower estrous behavior during the first contact with rams. Th... more Sexually inexperienced ewes display lower estrous behavior during the first contact with rams. The objective of this study was to determine whether sexually inexperienced anestrous females display estrous behavior and ovulatory activity as the sexually experienced females, and with restricted sexual experience exposed to photo-stimulated bucks. Six bucks were rendered sexually active during the non-breeding season by exposure to artificially long days (16 h of light and 8 h of darkness per day) for 2.5 months. The first group, sexually experienced females (n = 10) had physical contact with two vasectomized bucks, and mating was allowed; the second group, with restricted sexual experience (n = 10) had contact with two vasectomized bucks through a wire-mesh fence and mating was prevented; the third group, sexually inexperienced females (n = 9) was totally isolated from bucks. At 14-month-old the females were exposed to photostimulated bucks for 15 days. The proportion of females that displayed estrous behavior, ovulations, short and normal ovulatory cycles, and pregnancy rates did not differ between sexually experienced, with restricted sexual experience, and sexually inexperienced (P > 0.05, in all variables). Similarly, the ovulation rate did not differ between the three groups of females (P > 0.05). However, the interval from introduction of the bucks to the first estrus was shorter in sexually inexperienced females (P < 0.05). Therefore, sexually inexperienced anestrous females displayed estrous behavior, ovulation, and pregnancy rate similar to those displayed by sexually experienced and with restricted sexual experience when exposed to photo-stimulated bucks through the male effect.
International Journal of Animal and Veterinary Advances, 2013
The objective of the present study was to determine the accuracy and the negative prediction valu... more The objective of the present study was to determine the accuracy and the negative prediction value of Pregnancy-Associated Glycoprotein (PAG) at 29 d post artificial insemination by ELISA. Blood serums of multiparous Holstein cows were used (n = 275). Pregnancy diagnosis was carried out by rectal palpation at 40 d and it was considered as reference test. Pregnancy results based on the PAG-ELISA and the pregnancy diagnosis at 40 d showed high concordance with a kappa value of 0.7. The accuracy test based on PAG-ELISA at 29 d post artificial insemination compared with pregnancy diagnosis by rectal palpation was 88%. The values of sensibility, specificity, positive prediction value, negative prediction value and positive and negative likelihood ratio were 96, 78, 83 and 95%, 4.5 and 0.0442, respectively. It is concluded that pregnancy diagnosis of PAG-ELISA is reliable and accurate at 29 d post artificial insemination. The PAG-ELISA's negative prediction value diminishes the number of days in subjecting cows diagnosed as nonpregnant to diverse strategies of hormonal synchronization protocols.
Some breed of goats originating or adapted to subtropical latitudes display large seasonal variat... more Some breed of goats originating or adapted to subtropical latitudes display large seasonal variations of their sexual and/or reproductive activity. This seasonality causes a seasonality of milk, cheese and meat production. To solve this problem it is necessary to have a deep knowledge of the annual sexual activity of animals and to identify the environmental factor controlling the timing of the annual reproductive cycle. In this review we will describe our approach to develop sustainable techniques to control reproductive activity in goats from subtropical Mexico: (1) The characteristics of the annual breeding season in both male and female goats were determined; (2) Photoperiod was identified as the major environmental factor controlling the timing of the annual breeding season; (3) Photoperiod treatments were used to stimulate the sexual activity of bucks during the non-breeding season; (4) Male goats rendered sexually active were used to induce and synchronize the estrous behavio...
This study was designed to determine whether any relationship exists between exposure to artifici... more This study was designed to determine whether any relationship exists between exposure to artificial long days, milk yield, maternal plasma insulin-like growth factor 1 (IGF-1) levels, and kid growth rate in goats. One group of lactating goats was maintained under naturally decreasing day length (control group; n = 19), while in another one, they were kept under artificial long days (LD group; n = 19). Milk yield was higher in goats from the LD group than that in the control group (P < 0.05). Maternal IGF-1 levels at day 57 of lactation were higher (P < 0.05) in goats from the LD group than the levels in the control group and were positively correlated with the total milk yields per goat at days 43 and 57 of lactation (r = 0.77 and r = 0.84, respectively; P < 0.01). Daily weight gain at week 4 was higher (P < 0.01) in kids from the LD group than that in kids from the control group and was correlated with total and average IGF-1 maternal levels (r = 0.60 and r = 0.60, P < 0.05). It was concluded that submitting lactating goats to artificial long days increases milk yield, plasma IGF-1 maternal levels and the growth rate of the kids.
SummaryThe objective of this study was to determine the genetic diversity of creole cattle in nor... more SummaryThe objective of this study was to determine the genetic diversity of creole cattle in northwestern Mexico using the BoLA-DRB3.2 locus of the Major Histocompatibility Complex (MHC). A total of 56 creole cattle were sampled from five communities; in the state of Chihuahua (Cerocahui, Guadalupe y Calvo and Cuauhtémoc) and in the state of Baja California Sur (La Paz and Mulegé). The BoLA-DRB3.2 locus was genotyped by PCR-RFLP assay. Thirty-nine alleles were identified, out of which 14 had not been previously reported. The average level of inbreeding in all populations analyzed wasFIS= 0.09 (P< 0.0001), but only two populations (Cerocahui and Guadalupe y Calvo) showed an excess of homozygotes (P< 0.05). The breed differentiation in all populations studied wasFSC= 0.068 (P< 0.0001). The smallest genetic distance was between La Paz and Mulegé (0.022); but Mulegé presented smaller distances (0.028–0.053) with the populations of La Paz (0.071–0.083) and with Chihuahua. Baja ...
The present study was carried out to determine whether the presence of photostimulated sedated ma... more 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.
Under temperate and subtropical latitudes, ewes and goats display a reproductive seasonal pattern... more Under temperate and subtropical latitudes, ewes and goats display a reproductive seasonal pattern and their sexual activity during the anestrous period can be stimulated and synchronized by the introduction of males in the group, which is called the "male effect". The response of females to the male effect in the middle of the anestrous season is weak or absent. This failure may be due to the inability of the female to respond to males, as a result of a refractoriness of the female to the male stimulus. But, it may also be due to a low quality stimulus provided by the male which is, as the females, in seasonal rest. We tested this latter hypothesis in seasonally inactive goats kept under subtropical conditions by comparing the use of males with their sexual behavior stimulated or not by photoperiodic treatments. Treated males were able to induce estrous activity of females during the whole anestrus season. We have also determined that previous separation of the males and continuous contact during teasing are not absolute requisites when active bucks are used. While odor from the male and its sexual behavior play a primary role in inducing ovulation, vocalizations appear to facilitate the display of the does' estrous. It remains to be determined to which extent these conclusions apply under temperate latitudes and with more seasonal breeds. goat / male effect / buck vocalizations / male odor / sexual behavior / photoperiodic treatment
The objective of the present study was to determine whether parity is a factor that influences th... more The objective of the present study was to determine whether parity is a factor that influences the estrous and ovulatory responses of female goats when they are stimulated by males that show increased sexual activity. To stimulate sexual activity, four adult male goats were subjected to photoperiodic treatment for 2.5 months comprising long days, with the treatment commencing on 1 November. On 14 April at 1,900 h, a group of multiparous females (n=21) and a group of 16 months-old nulliparous females (n=19) were exposed to four bucks (two per group) for 15 days. Throughout the study period, the estrous behavior of these female goats was detected twice on a daily basis. Ovulations of the female goats were determined by ecography on days 7 and 18 after exposure to males. The sexual behavior of males was recorded twice every day from 0800 to 0900 h and from 1730 to 1,830 h during the first 4 days after introduction in the pen of females. The total cumulative proportion of multiparous females that had ovulations (100%) and displayed estrous behavior (100%) during the 15 days of exposure to males did not differ (P&amp;amp;gt;0.05) from that of nulliparous females (100% and 95%, respectively). The interval between introduction of males and onset of estrous behavior did not differ (P&amp;amp;gt;0.05) between multiparous (1.9+/-0.1 days) and nulliparous (1.7+/-0.2 days) females. The proportion of females displaying a short estrous cycle was greater (P&amp;amp;lt;0.05) in multiparous (13/21, 62%) than in nulliparous (5/19, 26%) females. Duration of these shorter than typical estrous cycles did not differ (P&amp;amp;gt;0.05) between groups (multiparous: 5.2+/-0.3 days, nulliparous: 4.5+/-0.1 days). The number of anogenital sniffings was greater (P&amp;amp;lt;0.001) in males exposed to nulliparous than in those exposed to multiparous females. In contrast, the number of mounting attempts was greater (P&amp;amp;lt;0.01) in males that were introduced to multiparous than in those that were introduced to nulliparous does. The number of flehmen, nudging, self-marking with urine, and mounts was not different (P&amp;amp;gt;0.05) between males that were in contact with multiparous and nulliparous females. These results indicate that regardless of parity, female goats respond to male introduction if they are stimulated by males that were previously exposed to artificial long days to increase their sexual behavior.
How to cite Complete issue More information about this article Journal's homepage in redalyc.org ... more How to cite Complete issue More information about this article Journal's homepage in redalyc.org Scientific Information System Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Non-profit academic project, developed under the open access initiative
We investigated whether live vocalizations emitted by bucks interacting with anestrous females st... more We investigated whether live vocalizations emitted by bucks interacting with anestrous females stimulate secretion of LH, estrous behavior and ovulation in anestrous goats. In experiment 1, bucks rendered sexually active by exposure to long days followed by natural photoperiod were exposed in a light-proof-building to five anestrous females. Buck vocalizations were reproduced through a microphone-amplifier-loudspeaker system to an open pen where one group of goats (n=6) was exposed for 10 days to these live vocalizations. Another group of females (n=6) was isolated from males and vocalizations. The proportion of goats displaying estrous behavior was significantly higher in females exposed to buck vocalizations than in females isolated from males. The proportion of goats that ovulated did not differ between the 2 groups (exposed to males versus isolated). In experiment 2, female goats that either had previous contact with males (n=7), or no previous contact with males (n=7) were exposed to live buck vocalizations, reproduced as described in experiment 1, for 5 days. The number and amplitude of LH pulses did not differ between groups before exposition to buck vocalizations. Five days of exposure to male vocalizations significantly increased LH pulsatility only in females that had previous contact with males, while LH pulse amplitude was not modified. We concluded that live buck vocalizations can stimulate estrous behavior and LH secretion in goats if they have had previous contact with bucks.
We investigated whether LH secretion, estrous behavior and fertility would differ between sexuall... more We investigated whether LH secretion, estrous behavior and fertility would differ between sexually inexperienced and experienced anestrous goats exposed to the males. Male goats were rendered sexually active during the reproductive rest season by exposure to 2.5 months of artificial long days. Two groups of anovulatory sexually inexperienced and sexually experienced does were exposed to males during 15 days (n = 20 per group). LH pulsatility was determined every 15 min from 4 h before to 8 h after introducing males (Day 0). Estrous behavior was recorded twice daily. Pregnancy rates were determined on Day 50. Fertility was determined at parturition. Male sexual behavior was registered on days 1 and 2 during 1 h. Before introducing the males, the number of LH pulses did not differ between groups. After introduction of the males, all females increased their LH pulsatility, but the number of pulses did not differ between sexually inexperienced and experienced goats. The proportion of females displaying estrous behavior with a high pregnancy rate and fertility did not differ between inexperienced and experienced goats. The sexual behavior of the males did not differ significantly between those interacting with sexually inexperienced or experienced goats. We conclude that goats can show substantial endocrine and reproductive responses to males, even in the absence of previous sexual experience, when sexually active bucks are used.
Fernández, I.G., Salgado, R.H. and Vázquez, C.A.E. 2010. Two 250 mg doses of bovine somatotropin ... more Fernández, I.G., Salgado, R.H. and Vázquez, C.A.E. 2010. Two 250 mg doses of bovine somatotropin increase conception rate, IGF-I plasma concentration and reduce the days to estrus in Holstein cows following estrus synchronization. J. Appl. Anim. Res., 37: 101–104.To determine whether the administration of two low doses of recombinant bovine somatotropin (bST, 250 mg each) improves conception rate in Holstein cows when using a. protocol of estrus synchronization 266 multiparous, postpartum first service Holstein cows were used. Control cows (CON; n=158) were injected with placebo and bST cows (TRT; n=108) received two doses of 250 mg of bST on d 56 and 67±2 d (at the time of AI). Insulin-like growth factor-I plasma concentration was higher in TRT cows (d 58; P<0.01 and d 62; P<0.05) and conception rate was also higher in TRT cows (P<0.05). Days to estrus in TRT cows were shorter (62.2±0.8 vs 74.1±0.9; P<0.01). Milk production was higher in TRT cows (58 to 63 d; P<0.05). The results indicated beneficial effect of bST given in two divided doses in respect of conception rate, insulin-like growth factor-I plasma concentration and days to estrus in postpartum lactating dairy cows.
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