The introduction of sexually active bucks at different moments of the oestrous cycle does not modify the NEFAs or the IGF-1 concentrations

Non-esterified fatty acids (NEFAs) and Insulin-like growth factor-I (IGF-1) concentrations are modified after the induction of a "male effect". The present study examined the effect of the introduction of males into a group of females that were previously isolated from males, during different phases of the sexual cycle, to determine the changes to the NEFAs and IGF-1 concentrations. Sixty-four does were divided into six groups. The males were introduced with the females at different points after sponge removal. Introduction was carried out 48 h (n=10, Group 48H), 72 h (n=12, Group 72H), 4 days (n=10, Group 4 D), 13 days (n=10, Group 13 D) or 18 days after sponge removal (n=10, Group 18 D), and a control group was implemented that had no contact with males (n=12, Control Group). Plasma samples were taken every day to determine daily progesterone (P4) and NEFAs concentrations, and every second day for IGF-1 determination. No effects from the experimental groups were observed on the mean NEFAs or IGF-1 concentrations (p>.05). No differences between the time before male introduction and after male introduction were observed on the NEFAs concentrations (p>.05) or IGF-1 concentrations (p>.05). On the whole, only differences were observed in the NEFAs concentrations between the follicular and the luteal phases (9.48 ± 0.38 vs 8.15 ± 0.15mg/dL for follicular and luteal phases, respectively, p<.01). The results of the present experiment demonstrated that the introduction of sexually active males at different moments of the oestrous cycle does not modify the NEFAs or the IGF-1 concentrations.This study was funded by Grant [AGL2016-75848-R] from MINECO-AEI-FEDER (Spain)

The use of photoperiod-treated bucks to induce a “male effect” does not compensate for the negative effects of nutritional restriction of the females in Mediterranean goats

This work examined the effect of acute nutritional restriction or supplementation one week before male introduction on the reproductive performances of the “male effect” when using photostimulated or control males in goats. On 22 March, 84 anoestrous does were placed with photostimulated bucks or with bucks which had received no treatments. One week before male introduction, the females were provided with different nutritional regimes: Supplemented, restricted or control females. The non-esterified fatty acids (NEFAs) and Insulin Growth Factor-1 (IGF-1) concentrations were measured in the same samples. Fecundity, fertility, prolificacy and productivity were also determined. No interaction between both sources of variation was observed in any of the reproductive variables studied. Treatment of the bucks increased the percentage of females expressing behavioural oestrous associated with ovulation (71% vs 90% for Natural and Photo groups, respectively, P < 0.05). The Supplemented females showed higher ovulation rate than Restricted females (1.77 ± 0.13 vs 1.05 ± 0.05, P < 0.001), fecundity (71% vs 43%, P < 0.05); fertility (76% vs 29%, P < 0.05) and productivity (1.00 ± 0.15 vs 0.29 ± 0.11 kids per female, P < 0.01). In the Supplemented females, the higher reproductive results could be due to the lower NEFAs and higher IGF-1 concentrations at ovulation and at the time of oestrus compared to the Restricted females. Thus, the present experiment results demonstrate that nutrition is an important factor in the response to the “male effect” at Mediterranean latitudes, and its negative effect cannot be counterbalanced by using photostimulated bucks.This study was funded by Grant AGL2016-75848-R from MINECO- AEI-FEDER (Spain).The authors wish to thank the farm staff of Huelva University for their technical support. Funding for open access charge: Universidad de Huelva/CBUA

Exogenous melatonin does not improve the freezability of Blanca Andaluza goat semen over exposure to two months of short days

This paper compares the effects of exposure to exogenous melatonin (MEL), short days (SD, 8 h of light) and long days (LD, 16 h of light), on reproductive activity, sperm motility and other reproductive variables, in Blanca Andaluza bucks. Fourteen males were spilt into two groups of seven animals (G1 and G2). They were subjected to five alternations of 2 months of LD followed by 2 months of SD or MEL before the experimental period of three consecutive intervals of: (1) 2 months of SD (G1, N = 7) or MEL (G2, N = 7); (2) 2 months of LD (G1 + G2, N = 14); and (3) 2 months of SD (G2, N = 7) or MEL (G1, N = 7). Plasma testosterone concentration, live weight, testicular weight and fresh semen quality were determined weekly. Semen was also cooled and frozen–thawed every fortnight, and the same quality variables measured as for fresh sperm. When the bucks were under LD treatment, the testosterone concentration was lower than when under MEL or SD treatment (P < 0.01); values for the semen concentration and total number of sperm per ejaculate were also higher (P < 0.001). No differences were observed between the MEL and SD treatments in terms of fresh, cooled or frozen–thawed sperm quality. Only some quality variables on fresh semen were improved by MEL and SD treatment (P < 0.05). In conclusion the results of the present experiment showed that MEL improved the fresh semen motility variables, but this did not improve the motility of frozen–thawed sperm over that recorded for either SD or LD treatment

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

Efecto de la melatonina durante el anestro estacional en la reactivación de la actividad sexual y producción seminal durante la estación reproductiva de machos cabrios del mediterráneo

One experiment was conducted to determine if the onset of the reproductive activity and semen production could be modified by a previous treatment with exogenous melatonin, used to enhance reproductive activity during the seasonal anoestrous in Mediterranean bucks. Two balanced groups of bucks were used. The 18th march 2005, one group (M group) received 3 s.c. implants of melatonin (N=7) and other group (N=4) was used like control (C group). From June to September, body weight and testosterone was measured weekly and testicular weight every 15 days. The reproductive activity of each buck was assessed using characteristics of the testosterone profile. During the first 8 days of each month, volume of ejaculate and sperm concentration was assessed. Each of these 8-d periods was divided into 3-d periods of daily sperm collection separated by 2 d of rest. The semen was collected using an artificial vagina. The effect of treatment and month was studied on each variable. An interaction, month-treatment was observed on ejaculate volume, July was the month with higher volume (0.62 ± 0.06 mL vs 1.07 ± 0.15 mL for M and C group respectively, P < 0.05). Sperm concentration was influenced by treatment (6.13 x109 ± 2.49 x108 vs 4.26 x109 ± 3.12 x108 sperm/mL, for M and C, respectively, P < 0.05). The onset of the reproductive activity, after the study of the testosterone concentrations was similar for both groups (31st August ± 7.89 days and 4th September ± 25.66 days for M and C group, respectively). Results demonstrate that melatonin treatment during the seasonal anoestrous does not influence the onset of the normal breeding season or ejaculate volume but it seems that could increases the sperm concentration at the normal breeding season in Mediterranean goat males

Seasonal changes in reproductive activity, sperm variables and sperm freezability in Blanca Andaluza bucks

Interest in the preservation of endangered breeds such as the Blanca Andaluza goat, has increased and some steps should be therefore taken to ensure it. The study was designed to determine the seasonal reproductive pattern of Blanca Andaluza bucks, and whether this affects the quality of their semen and its freezability over the year. Seven bucks were used and their body weight, testicular weight, plasma testosterone concentration and fresh sperm quality determined every week. The collected sperm was cryopreserved and stored; it was then thawed and the same sperm quality variables measured every fortnight. High plasma testosterone concentrations were recorded during the summer and autumn, and low concentrations were recorded during winter and spring (p<0.001). No differences were seen between seasons in terms of the percentage of bucks ejaculating, the percentage of active bucks, or ejaculate volume. However, the sperm concentration, the total number of sperm per ejaculate, and the values for most fresh sperm variables were lower during the winter period (at least p<0.05). After freezing-thawing, the quality of winter-collected sperm was better, in some respects, than that of summer-collected sperm (at least p<0.05). These results reveal that Blanca Andaluza bucks show seasonal reproductive activity in terms of their plasma testosterone concentration, but no clear change in their sexual behaviour between seasons was observed. The values of fresh sperm variables also vary over the year, reaching their lowest during winter. However, after freezing-thawing, winter-collected sperm is of overall better quality than sperm collected during the summer

Utilización de fotoperiodo e implantes de melatonina para el control de la reproducción en caprinos mediterráneos

El fotoperiodo es el principal factor medioambiental que controla la actividad reproductiva en caprino y es interpretado por el animal por la variación en la secreción de melatonina. La especie caprina presenta variaciones en su actividad reproductiva a lo largo del año en relación con el fotoperiodo, de manera que los días cortos estimulan su actividad reproductiva y los días largos la inhiben. El hecho de que su actividad reproductiva sea estacional, conlleva importantes variaciones en sus producciones a lo largo del año. De este modo, las técnicas de control de la reproducción caprina permiten una mejor distribución de sus producciones, leche y carne, a lo largo del año. Los tratamientos fotoperiódicos, se basan en la alternancia entre los días largos y cortos. En primer lugar los animales son sometidos a días largos, para que estén preparados para responder al efecto estimulatorio de los días cortos. Estos tratamientos fotoperiódicos inducen actividad reproductiva tanto en machos como en hembras, al igual que los tratamientos hormonales. Respecto a la melatonina, la autorización comercial en España de implantes de melatonina para mejorar los resultados reproductivos en la especie caprina se produjo en el año 2009. Estos implantes provocan un incremento de las concentraciones en sangre de esta hormona que hace que el animal interprete que se encuentra en días cortos y por tanto estimula su actividad reproductiva. El protocolo de utilización, recomendado habitualmente, incluye la colocación los implantes tanto en las hembras como en los machos entorno al equinoccio de primavera, previa separación de ambos sexos durante al menos 45 días. Este tratamiento permite incrementar, con respecto a las hembras no tratadas, la fertilidad y en consecuencia la producción de chivos y, en consecuencia, el número de cabras que van a producir leche.The photoperiod is the main environmental factor that controls reproductive activity in goats, and their information is transduced by the melatonin secretion. Goats show a seasonal pattern in reproductive activity related to the annual variations of photoperiod. Short days stimulate the reproductive activity and long days inhibit it. The fact that their sexual activity is seasonal affects the distribution of their production over the year and this is a problem both in dairy and meat production systems which attempt to have a constant production year-round. Techniques used to control reproduction in goats allow greater distribution of milk and meat production throughout the year. In this way, photoperiod treatments are based on alternation of long and short days. First, the animals are subjected to long days in order to prepare them to respond to the stimulatory effects of subsequently administered short days. These photoperiodic treatments can induce sexual activity in males and females similarly to hormonal treatment in females. The commercial use of melatonin implants in Spain for goats was approved on 2009. The melatonin implants induces an increase on the plasma melatonin concentrations as a short day and stimulates reproductive activity. The procedure of application includes the insertion of the melatonin implants on the females and males during the seasonal anoestrous and isolation of the both sexes during 45 days. This allows increasing the reproductive performances as fertility and in consequence the number of milking goats

Utilización de fotoperiodo artificial, melatonina exógena y/o efecto macho para la mejora de los parámetros reproductivos de caprinos mediterráneos

El objetivo de este trabajo ha sido evaluar la utilización del fotoperiodo artificial, la aplicación de melatonina y el efecto macho para inducir actividad reproductiva durante el periodo de anestro estacionario en caprinos Mediterráneos. Para la consecución de este objetivo se llevaron a cabo cinco experimentos. De los resultados obtenidos, se puede concluir que tanto la utilización de implantes de melatonina entorno al equinoccio de primavera como el tratamiento con fotoperiodo artificial de días largos antes de colocar el implante de melatonina provocan, en hembras y machos, desencadena actividad reproductiva durante el anestro estacionario. Sin embargo, el tratamiento sólo con tres meses de días largos en hembras no fue capaz de provocar celos de forma masiva durante la primavera y fue el tratamiento que resultó menos efectivo en los machos. El protocolo de utilización de los implantes de melatonina resultó ser cuando al menos las hembras son tratadas con melatonina.The main aim of this work was to evaluate the effect of different treatments on the reproductive parameters during the non-breeding season in Mediterranean goats, including the use of exogenous melatonin, artificial long days and male effect. For this aim, five experiments were conducted. According to the obtained results we can conclude for Mediterranean goats, that the use of melatonin implants around the spring equinox and 3 months of artificial long days before a treatment with exogenous melatonin are able to induce reproduce activity in females and males during the non-breeding season. However, the treatment with three months of long days was not able to induce oestrous activity during the seasonal anoestrous and was less effective in terms of percentage of ejaculating or active males. Concerning the melatonin procedure, the higher reproductive performances were obtained when at least females were treated with melatonin

Role of body condition score and body weight in the control of seasonal reproduction in Blanca Andaluza goats

The reproductive activity of 84 female Blanca Andaluza goats was monitored over 17 months to determine the role of body condition score (BCS) and body weight (BW) in its control. Following a 3 × 2 factorial experimental design, the animals were allocated to three groups: low BCS (≤2.50, n = 24), medium BCS (BCS = 2.75–3.00, n = 31) and high BCS (≥3.25, n = 29). The same animals, irrespective of the BCS group categorization, were also divided into two groups depending on BW: low BW (≤40 kg, n = 44) and high BW (>40 kg, n = 40). Oestrus was evaluated daily using vasectomised males. The ovulation rate was assessed by trans-rectal ultrasonography after the identification of oestrus. Ovulations were determined by monitoring the plasma progesterone concentration weekly. The BCS and BW were recorded once a week and nutritional status adjusted to maintain the initial differences in BW and BCS between the groups. Both BCS and BW had a significant (at least P 40 kg. No significant interaction between these variables was observed. Some (11.7%) of the does in the groups with animals of BCS ≥ 2.75 had ovulations during seasonal anoestrus. None of the does with a BCS of ≤2.5 had ovulations during seasonal anoestrus. The ovulation rate of the first and last oestrus was influenced by BW (P < 0.01). These results demonstrate that Blanca Andaluza goats show marked reproductive seasonality that is clearly and independently modulated by BCS and BW

The reproductive performance of female goats treated with melatonin is not improved after introduction to bucks displaying springtime sexual activity if these does are experiencing decreasing body weight/condition score

The aim of the present work was to determine whether treatment with melatonin modifies the reproductive response of female goats experiencing increasing or decreasing body weight (BW)/body condition score (BCS) when introduced to bucks displaying springtime sexual activity. During natural anoestrus, 53 does were isolated from bucks for a period of 42 days and distributed into two groups: 1) low BW/low BCS animals (N = 24) (LLg group), which were fed 1.9 times their maintenance requirements so they would experience increasing BW and BCS; and 2) high BW/high BCS animals (N = 29) (HHl group), which were fed 0.4 times their maintenance requirements so they would experience decreasing BW and BCS. Half of each group was treated, or not, with melatonin (LLg + Mel N = 12, HHl + Mel N = 15, LLg-Mel N = 12 and HHl-Mel N = 14). On 6th May they were introduced to six males, showing natural sexual activity, fitted with marking harnesses (thus permitting the detection of oestrous activity). The ovulation rate was assessed by transrectal ultrasonography and confirmed via the plasma progesterone concentration (measured twice per week in blood samples). Plasma glucose, IGF-1 and non-esterified fatty acid concentrations were also determined, along with the conception rate, fertility, prolificacy and productivity of the does. LH concentrations and LH pulsatility were also recorded in the hours around introduction to the males. ‘Oestrous plus ovulation' was observed only in does treated with melatonin. A higher conception rate and greater fertility and productivity were observed among the LLg + Mel does. These females showed higher glucose and IGF-1 concentrations after the introduction of the males. LH concentrations increased after male introduction independent of all other conditions. In conclusion, the present results show that treatment with melatonin does not enhance reproductive performance in does experiencing decreasing BW/BCS, but can improve it when does are experiencing increasing BW/body fat reserves — even when exposed to males displaying only springtime sexual activity. This might be explained by the higher blood glucose and IGF-1 concentrations of the LLg + Mel females.The authors thank the Asociación Nacional de Criadores de Ganado Caprino de Raza Blanca Andaluza (ABLANSE) for supplying the animals used. This study was funded by grant AGL2012-31733 from MINECO (Spain). The authors are grateful to CEVA Salud Animal, Barcelona, Spain, for pro- viding the Melovine ® implantsThe authors thank the Asociacion Nacional de Criadores de Ganado Caprino de Raza Blanca Andaluza (ABLANSE) for supplying the animals used. This study was funded by grant AGL2012-31733 from MINECO (Spain). The authors are grateful to CEVA Salud Animal, Barcelona, Spain, for providing the Melovine (R) implants