Viability and fertility of unwashed Murciano-Granadina goat spermatozoa diluted in Tris-egg yolk extender and stored at 5 °C

Effect of the donor´s age and type of extender (egg yolk versus clarified egg yolk) over the sperm quality of Majorera bucks preserved at 4 ºC: in vitro results and fertility trials

This study assessed the effect of donor´s age and two different extenders in the sperm quality of chilled semen in Majorera bucks. In experiment 1, semen was individually processed from 5 young (10–12 months old) and 4 mature (3–5 years old) bucks and then was diluted in two different extenders: EY (Tris‐glucose, 12% egg yolk) and CEY (Tris‐glucose, 12% clarified egg yolk) and cooled at 4°C; semen quality (sperm motility, percentages of alive spermatozoa, acrosome status and abnormal spermatozoa) was evaluated at 24, 48, 72 and 96 hr after cooling. In experiment II, 72 Majorera goats were assigned to four experimental groups: for groups 24‐EY (n = 18) and 24‐CEY (n = 18), goats were inseminated with EY and CEY cooled semen for 24 hr, respectively, while for groups 72‐EY (n = 18) and 72‐CEY (n = 18), goats were inseminated with EY and CEY cooled semen for 72 hr, respectively. In vitro results confirmed that only ejaculate volume and sperm concentration were significantly different between young and mature bucks. In addition, semen quality was similar between both diluents, presenting values for the first 48 hr similar to that recorded in fresh samples. The fertility rate was around 70% after 24 hr (4°C) in both groups, but the kidding rate was significantly lower (44.4%, p < .05) in goats inseminated with EY diluent preserved for 72 hr. Our results showed that the semen samples may be stored at 4°C in media with egg yolk or clarified egg yolk, and, therefore, the use of clarified egg yolk may represent a valid alternative to chill semen samples. Finally, young bucks (older than 10–12 months) of Majorera breed could be successfully used in breeding programmes with similar efficacy to older males.

Cooled storage of semen from livestock animals (Part II): Camelids, goats, and sheep

This review is part of the Festschrift in honor of Dr. Duane Garner and provides an overview of current techniques in cooled storage of semen from livestock animals such as camelids, goats, and sheep. Facing worldwide environmental changes and a trend towards more conscious and healthy eating behaviors, the development of a stable animal breeding industry is a significant challenge for the near future. In the present review, factors influencing semen handling in camelids, goats and sheep are described and relevant methods as well as current trends to improve liquid-storage of cooled semen are discussed, including extenders, additives, cooling rates, and storage temperatures. The species-specific physiology and resulting challenges are taken into consideration. While the main problem for camelid semen processing is the relatively greater viscosity as compared with that of some other animals, the deciding factor for successful artificial insemination (AI) in goats and sheep is the site (i.e., cervical or vaginal) of semen placement in the reproductive tract. Due to the type of cervical anatomy, the penetration of the cervix when using AI instruments is rather difficult. Furthermore, the seminal plasma of small ruminants affects the interaction with milk-based extenders and egg yolk which results in species-specific regimens for cooled liquid-preservation. Comparing all three species, the greatest pregnancy rates were obtained by AI with goat semen after cooled liquid-storage for several days.

Seminal plasma contains TGF-β and CXCL10 but sperm washing before cryopreservation is beneficial for post-thawing sperm motility in Black Bengal goats (Capra hircus)

PROBLEM

Artificial insemination, which requires cryopreservation of semen, is not completely optimized in goats because bucks discharge a small volume of ejaculate and seminal plasma (SP) contains specific proteins that are detrimental to spermatozoa at cryopreservation. However, it is not known the effects of sperm washing (removal of SP) before cryopreservation on the post-thawing frozen spermatozoa of Black Bengal bucks. Moreover, it is completely unknown whether SP of goats contains TGF-β and CXCL10 that have been proven essential for fertility in other mammals.

METHODS

Thirty-five ejaculates were collected from six mature Black Bengal bucks at one-week intervals and were subjected to microscopic evaluation for semen characteristics at pre- and post-freezing condition. The concentrations of TGF-β and CXCL10 in the SP using ELISA were determined. SP was harvested with centrifugation of fresh semen at 1500 g for 15 minutes twice at room temperature.

RESULTS

Semen characteristics were significantly varied between bucks. Seminal plasma of all ejaculates contained TGF-β and CXCL10 while significant variation of concentrations between bucks was observed in case of CXCL10. Cryopreservation of semen reduced total motility and progressive motility, while sperm washing before cryopreservation was beneficial to the total motility and progressive motility of post-thawing spermatozoa.

CONCLUSION

Black Bengal buck seminal plasma was affluent of TGF-β and CXCL10 and washing of spermatozoa before cryopreservation was beneficial to the post-thawing sperm motility. The results of the current investigation will be helpful for future research on the roles of SP in female reproductive tract and pregnancy in Black Bengal goats.

Follicular dynamics during the oestrous cycle in dairy goats

Development of all follicles with antral diameter ≥2 mm during the oestrous cycle was characterized in goats of the Murciana-Granadina dairy breed by daily transrectal ultrasonography. Of nine does initially synchronized in oestrus, six returned to oestrus and three did not. In the first six does, mean cycle length was 21·2 (s.e. 2-3) days. There were mean total numbers of 6·2 (s.e. 0·6) small (2 to 3 mm), 1·9 (s.e. 0·3) medium (4 to 5 mm), and 1·0 (s.e. 0·2) large follicles (≥6 mm) each day but only numbers of large follicles differed with day of cycle (P < 0·01). The diameters of the largest follicle (LF1), the second largest (LF2) and the remaining follicles (RF) varied with day of cycle (P < 0·01). The LF1 and LF2 varied with day in similar patterns but the difference in diameter between them (P < 0·05) was greatest on days 7 and 9 (2·3 mm) and days 19 to 23 (2·2 to 3·8 mm), and least on days 2, 15, 16 and 18 (0·5 to 0·8 mm). The relationship between the LF1 and LF2 to the RF differed only early or late in the cycle when concentrations of progesterone were low (P < 0.05). There was some evidence to support follicular growth in waves. Although the number of apparently new follicles detected (4·8 (s.e. 0·4) per day) did not vary with day of cycle, follicles emerging at 3 mm over a 48-h period that grew to a diameter of ≥6 mm were distributed non-randomly in three of six cyclic does. The three cystic does that did not return to oestrus by day 25 had large follicles (16 to 28 mm), fewer new follicles (3·3 (s.e. 1-1) per day; P < 0·01) than cyclic does (4·8 (s.e. 0·4) per day) and fewer follicles that became largest (4·0 v. 8·8 in cyclic does; P < 0·01).

Comparative quality assessment of buffalo (Bubalus bubalis) semen chilled (5°C) in egg yolk- and soya milk-based extenders

Egg yolk-Tris is most commonly used semen extender; however, its use involves hygienic risk, interference with fertility and poor microscopic examination. Therefore, replacement of egg yolk with a plant-based component with protective effects on spermatozoa would be advantageous. In present study, we observed effect of soya milk-based extenders on dilution and liquid preservation of Murrah buffalo bull semen at 5°C up to 72 h in comparison with conventional egg yolk-Tris extender (Ext.1). In experiment one, a total of 32 buffalo semen ejaculates from four animals were extended and preserved at 5°C for 72 h in soya milk-based extender (Ext.2) with different percentages (10%, 15%, 20%, 25% and 30%) of soya milk for optimization of soya milk concentration. Semen quality was assessed for individual motility, viability, membrane integrity and acrosome integrity at 0, 24, 48 and 72 h of liquid preservation. The results of experiment one indicated that 25% soya milk is an optimum concentration for buffalo bull semen extender preparation. A modified method was used to prepare another soya milk-based extender (Ext.3). In the second experiment, two soya extenders (Ext.2 and 3) with optimized concentration (25%) of soya milk were comparatively assessed with egg yolk-Tris extender (Ext.1) for semen quality parameters at 0, 24, 48 and 72 h of liquid preservation. The individual sperm motility at 0 and 24 h following dilution were found non-significant among extenders. However, after 48 h of dilution, individual motility in Ext.3 was observed significantly (p < 0.05) higher than Ext.1. After 24, 48 and 72 h of dilution sperm membrane integrity in Ext.3 was found significantly (p < 0.05) higher than Ext.1. Overall, comparative evaluation of sperm parameters obtained revealed that Ext.3 containing 25% soya milk can be used as a substitute of egg yolk-based extender for buffalo semen liquid preservation.

Influence of the preservation temperature (37, 20, 4, -196°C) and the mixing of semen over sperm quality of Majorera bucks

This study assessed the effect of different semen storage temperatures and the influence of semen pooling in semen viability. In experiment 1, semen samples (n = 30) of five Majorera bucks were individually processed [Individual semen (IS)] and after the first dilution (Tris-yolk extender), semen-diluted aliquots from each male were pooled semen (PS). Thereafter, semen samples (IS and PS) were preserved as fresh semen (37 and 20°C), chilled semen (4°C) and frozen semen. Sperm motility and the percentage of abnormal sperm cells and intact membrane acrosomes were defined. Semen preservation at 20 and 4°C did not modify the quality of spermatozoa for the first 24 h, but the conservation at 37°C caused a dramatic fall in the semen motility from 12 h onwards. Furthermore, the longevity of frozen-thawed semen was limited to 4-6 h. No differences were observed in semen parameters when PS was compared with semen from individual males in any of the preservation protocols assessed. In experiment 2, 120 goats were distributed in four experimental groups: in group fresh individual semen (FIS, n = 30) and group frozen-thawed individual semen (FTIS, n = 30), does were transcervically inseminated with fresh semen and frozen-thawed semen from each individual male, respectively, and in group fresh pooled semen (FPS, n = 30) and group frozen-thawed pooled semen (FTPS, n = 30), goats were transcervically inseminated with FPS and FTPS, respectively. The kidding rate was very close in the FIS and FPS groups (70.0% and 73.7%, respectively), and no significant differences were observed in the fertility rate between FTIS and FTPS. The results of this study confirmed that semen samples may be preserved satisfactorily for 24 h both at 20 and 4°C. In addition, the mixture of semen of different bucks did not significantly modify the semen parameters when compared with semen from individual males.

Parâmetros reprodutivos de cabras Toggenburg inseminadas com sêmen resfriado, após diluição em meio à base de gema de ovo

Avaliaram-se a taxa de concepção, a resposta à prostaglandina, a duração do estro, a categoria reprodutiva e o tipo de muco de cabras inseminadas com sêmen diluído em meio à base de gema de ovo e resfriado a 5ºC, por 12 ou 24 horas. Foram utilizados dois reprodutores e 62 fêmeas da raça Toggenburg, que receberam duas doses de 22,5µg de PGF2α, em intervalos de 10 dias, para a sincronização do estro. A partir da primeira aplicação de PGF2α, o estro foi monitorado três vezes ao dia. Realizou-se uma única inseminação, 12 horas após o início do estro. As porcentagens de fêmeas em estro, após a primeira e segunda aplicações de PGF2α, foram de 85,5% e 88,7%, respectivamente. O intervalo de aplicação da primeira e segunda doses de PGF2α ao início do estro foi de 41,04±20,32 e 45,67±9,28 horas, e a duração do estro de 40,02±15,96 e 32,24±12,09 horas, respectivamente. A taxa de concepção total foi de 49,1%. O período de armazenamento do sêmen e a categoria reprodutiva não influenciaram (P>0,05) a taxa de concepção. O tipo de muco observado no momento da inseminação influenciou (P<0,05) a fertilidade das fêmeas, sendo o de aspecto estriado associado aos maiores índices de concepção.

Taxa de concepção de cabras inseminadas com sêmen caprino resfriado a 5ºC, por 12 ou 24 horas, em meio diluidor à base de gema de ovo

Avaliou-se a capacidade fecundante do sêmen caprino resfriado a 5ºC, por 12 (TI) ou 24 horas (TII), em container especial. Para tanto, utilizaram-se 62 fêmeas e dois reprodutores (B1 e B2) da raça Toggenburg, distribuídos em um esquema fatorial 2x2 (dois reprodutores e dois períodos de estocagem do sêmen). Após a coleta, o sêmen foi diluído em Tris-frutose-gema de ovo a 2,5%, envasado em palhetas de 0,25mL, com 150x10(6) espermatozoides móveis e resfriado a 5ºC. As fêmeas receberam duas doses de 22,5µg de PGF2α, em intervalos de 10 dias para a sincronização do estro. A partir da primeira aplicação de PGF2α, as fêmeas foram monitoradas para ocorrência de estro, três vezes ao dia. Realizou-se uma única inseminação, pela técnica de fixação da cérvice, 12 horas após o início do estro. A motilidade e o vigor, após 12 ou 24 horas de resfriamento, foram de 66,14±0,11% e 62,50±0,05%, e 3,46±0,61 e 3,27±0,50, respectivamente. Não houve influência (P>0,05) do reprodutor, nem do período de armazenamento do sêmen sobre a taxa de concepção das cabras, que foi de 49,1%.

Effect of solid storage on caprine semen conservation at 5°C

In this work, we investigated the effect of storage in solid-phase extender on buck semen conserved at 5 degrees C. Furthermore, we studied the effect of addition of cysteine to the extender and the washing of seminal plasma on sperm survival. In Experiment 1, milk-based extender (M) was used as a control to study the effect of solid media storage (G) and cysteine supplementation (C), and the combination of both (GC), on in vitro sperm survival of washed and non-washed semen, conserved up to 72 h at 5 degrees C. Motility, acrosome integrity (NAR) and hypo-osmotic swelling tests (HOST) were evaluated to assess in vitro sperm survival. In Experiment 2, an artificial insemination (AI) field trial was performed to compare G versus M. Solid media (G) maintained motility of spermatozoa during storage higher than any other extender (67% G versus 62% GC; 61% M and 59% C; P<0.05), but there was no difference in NAR or HOST between extenders (P>0.05). No improvement in sperm viability was obtained by addition of cysteine to the media. Washing of semen improved motility (65% versus 60%; P<0.05), NAR (70% versus 64%; P<0.05) and HOST (37% versus 28%; P<0.05). No significant differences in fertility were obtained between G and M extenders (47% versus 41%; P>0.05). In conclusion, washing of semen and dilution in gelatin-supplemented milk extender (solid storage) appears to be a successful method for goat semen storage at 5 degrees C.

Factors Affecting Pregnancy Rate in Artificial Insemination with Frozen Semen During Non-Breeding Season in Murciano-Granadina Goats: a Field Assay

An artificial insemination programme was carried out to study the effect of factors such as depth of semen deposition, inseminator skill, farm, sire and expression of oestrus on pregnancy rate in Murciano-Granadina (MG) goats during non-breeding season and using frozen semen. Frozen-thawed semen from six males was applied by three technicians to inseminate a total of 551 goats in 17 farms distributed throughout the Mediterranean area of Spain. Pregnancy rate was determined at 6 weeks after insemination by transabdominal ecography. Overall pregnancy rate was 57%. Farm and depth of semen deposition affected pregnancy rate, whereas the sire and the technician had no effect. The deeper the semen was deposited in the genital tract, the higher was the rate of pregnancy obtained, being greater when the catheter reached the uterus. In spite of the relevant difference observed (48.2% vs 59.0%), pregnancy rate of females not coming into oestrus until 30 h after sponge removal was not significantly different, compared with those showing oestrus during the OD procedure. In conclusion, our field assay data on AI in MG goat with frozen-thawed semen showed that post-cervical insemination presented significantly greater pregnancy rate in comparison to when semen is deposited in the vagina or in the caudal part of the cervix.

Effect of changing female stimulus on intensive semen collection in young Murciano-Granadina male goats1

The aim of this research was to study the effect of changing female stimulus on libido and semen characteristics from young Murciano-granadina male goats submitted to intensive semen collection using females not in estrus as teasers. Males were submitted to two different sexual stimulation procedures. In the first procedure, the same doe was used as the female stimulus for three consecutive presentations. In the second, the doe was replaced after the second presentation by a new female. Semen volume, concentration, forward progressive motility, and live spermatozoa were scored. To analyze reaction time (RT), three types of analysis were performed. In the first one, RT was analyzed by multifactor ANOVA, taking as a missing value 300 s when a buck did not ejaculate. In the second, RT also was analyzed by multifactor ANOVA, but data from males that did not ejaculate were removed. In the third, a Cox Survival analysis was carried out by censoring data when a buck did not ejaculate within 5 min of entering the test arena. A decrease in semen volume and sperm concentration in the successive ejaculations was observed, being highly marked in the third ejaculation independent of the stimulation procedure (0.62 vs. 0.38 and 0.43 mL, and 2,828 vs. 2,183 and 2,223 million spermatozoa/mL to the first and third ejaculation respectively; P < 0.05). No significant differences were observed either in forward progressive motility or live sperm rate. Changing the female stimulus in the third presentation had no significant effect on any seminal characteristic. Regarding libido and mounting behavior variables, there was a substantial decrease in RT in the third service when the female was changed (with both types of ANOVA). When censored data were taken into account, the relative risk showed that the probability of a male ejaculating in the third presentation increased almost fourfold when the female was replaced than when the female was the same in all services (P < 0.05). In conclusion, young Murciano-granadina bucks can be used as semen donors because none of the most important semen variables used to reject or accept an ejaculate before freezing process decreased after intensive semen collection. We also recommend changing the female stimulus to make the semen collection procedure more efficient and using survival analysis methodology to analyze time data, mainly when a high rate of censored data are scored.