Selection responses for the number of fertile eggs of the Brown Tsaiya duck (Anas platyrhynchos) after a single artificial insemination with pooled Muscovy (Cairina moschata) semen

A seven-generation selection experiment comprising a selected (S) and a control (C) line was conducted with the objective of increasing the number of fertile eggs (F) of the Brown Tsaiya duck after a single artificial insemination (AI) with pooled Muscovy semen. Both lines consisted of about 20 males and 60 females since parents in each generation and each female duck was tested 3 times, at 26, 29 and 32 weeks of age. The fertile eggs were measured by candling at day 7 of incubation. The selection criterion in the S line was the BLUP animal model value for F. On average, 24.7% of the females and 15% of the males were selected. The direct responses to the selection for F, and correlated responses for the number of eggs set (Ie), the number of total dead embryos (M), the maximum duration of fertility (Dm) and the number of hatched mule ducklings (H) were measured by studying the differences across the generations of selection between the phenotypic value averages in the S and C lines. The predicted genetic responses were calculated by studying the differences between the S and C lines in averaged values of five traits of the BLUP animal model. The selection responses and the predicted responses showed similar trends. There was no genetic change for Ie. After seven generations of selection, the average selection responses per generation were 0.40, 0.33, 0.42, 0.41 genetic standard deviation units for F, M, Dm, and H respectively. Embryo viability was not impaired by this selection. For days 2–8 after AI, the fertility rates (F/Ie) were 89.2% and 63.8%, the hatchability rates (H/F) were 72.5% and 70.6%, and (H/Ie) were 64.7% and 45.1% in the S and C lines respectively. It was concluded that upward selection on the number of fertile eggs after a single AI with pooled Muscovy semen may be effective in ducks to increase the duration of the fertile period and the fertility and hatchability rates with AI once a week instead of twice a week.     

Comparison of fertility and embryo mortality following artificial insemination of common duck females (Anas Platyrhynchos) with semen from common or Muscovy (Cairina Moschata) drakes

The purpose of this study was to compare fertility and early embryo mortality rates (< or = 5 days of incubation) following artificial insemination (AI) of common duck females (Anas Platyrhynchos) with semen from either common or Muscovy (Cairina Moschata) drakes at various periods of the reproductive season (Period I, 27-35 weeks; Period II, 39-43 weeks and Period III, 49-56 weeks). Based on observations performed by stereomicroscopy on eggs laid from Days 2 to 10 after AI, we confirmed that fertility was significantly lower in the interbred compared to the purebred cross at each of the periods tested (purebred 58.1, 61.2 and 54.2 versus crossbred 31.0, 40.4 and 39.5 at Periods I, II and II, respectively; 0.01 < P < 0.001). In a complementary experiment, we demonstrated that the number of perivitelline spermatozoa (NPS) was markedly lower in mule (crossbred) eggs compared to common (purebred) eggs, a strong indication that initial sperm selection occurring in the lower oviduct is probably more intense after crossbred compared to purebred insemination. Comparison of early embryo mortality (EEM) between mule and common duck eggs indicated that increased levels of EEM in mule embryos corresponded to Stages II-IV of the Eyal-Giladi and Kochav classification (EGK). While a similar age-dependent increase in early embryo mortality was observed in eggs from both genetic origins during the latter periods of the reproductive season, it was also established that embryo mortality due to parental age was related rather to Stages X-XIV of the EGK classification in eggs from both genetic origins. It is concluded that the relative subfertility of mule compared to common duck eggs is probably the consequence of a more intense rate of selection of heterologous than homologous spermatozoa occurring in the vaginal portion of the oviduct while the causal origins of EEM in mule duck eggs can at least in part be identified on the basis of precise staging (by stereomicroscopy) of dead embryos.     

Duration of fertility and hatchability of the common duck (Anas platyrhynchos) in pure- or crossbreeding with Muscovy drakes (Cairina moschata)

A total of 540 common duck dams were used for a comparison of duration of fertility and hatchability between eggs issued from common dams inseminated with sperm (175 x 10(6) dose(-1)) from either common (pure-breeding or PB) or Muscovy (crossbreeding or CB) drakes. Artificial inseminations (AI) were performed at 3 periods of the reproductive season (27-35, 39-43 and 49-56 weeks) with 2 alternate inseminations/period at 3-week intervals (one with semen from common and the other from Muscovy). Fertility was estimated from egg candling while early embryo mortality (EEM), medium embryo mortality (MEM) and late embryo mortality (LEM) was estimated on Days 0-6 (PB+CB), Days 7-25 (PB) or Day 28 (CB) of incubation, and after, respectively. Overall fertility from Days 2-12 after AI was 61.1% in PB and 42.8% in CB. The maximum duration of fertility (time interval between AI and last fertile egg) was 8.1 days in PB versus 6.4 days in CB (p<0.05). The age of the dam influenced this interval, particularly in PB, with a longer duration at 40 weeks compared to 50 (p<0.05). On average, EEM represented 2.5% of fertile eggs while MEM accounted for 5% of surviving embryos on Day 6 and LEM, for 11.5% of hatched eggs. MEM was significantly higher in CB (6.3%) compared to PB (3.9%; p<0.05). Overall, an increase in EEM and MEM was observed in both types of eggs at and after 50 weeks of age. An increase in EEM (regardless of dam's age) and in MEM (only in the oldest females) was observed with sperm storage duration. Sex ratio at hatching (49.2% males in PB vs. 53.0% in CB) was particularly unbalanced on the first fertile day (54.7% and 57.1%, respectively).     

Sex ratios in mule duck embryos at various stages of incubation

Mule duck hatcheries have long reported varying degrees of unbalance in the sex ratio, with a preponderance of male mules at hatching. The aim of the present study was to assess the distributions of sex ratios at various stages of development in embryos originating from intra- and intergeneric crosses between parental lineages (Muscovy male x Muscovy female, Pekin male x Pekin female, Muscovy male x Pekin female or Mule, and Pekin male x Muscovy female or Hinny). In Experiment I, embryo sexing was performed on Days 1 and 5 of incubation (by multiplex PCR) and at hatching (by vent observation). The sex ratio was not significantly modified during the early stages of embryo development whatever the genetic origin (P>0.05, Days 1 and Day 5) but our results in mule and hinny ducklings confirmed the preponderance of males among normally hatched ducklings originating from the intergeneric lineage (58.9 and 55.4% males in mules and hinnies, respectively; P<0.05 in both cases). Sex ratio (vent sexing) in second grade (cull) ducklings revealed that 68% of these ducklings were females (P<0.05). In Experiment II, the distribution of sex ratio was also performed in mule duck eggs from 6 batches (400,000 eggs/batch) first examined for fertility (candling) on Day 18 of incubation. These results indicate that the percentage of males present in the population of normally hatched ducklings increases when fertility decreases. In addition, this experiment also revealed that 83.7-90.5% of viable male mule embryos develop up to hatching, compared to only 43.0-51.0% of female mule embryos. Given that a deviation in sex ratio during the first stages of incubation is unlikely (Experiment I), it is concluded that the skewed sex ratio of mule ducks at hatching is primarily due to increased late mortality in female mule embryos occurring between egg transfer and hatching. This mortality originated, at least in part, from the intergeneric origin of female mules, and was marked to a greater or lesser extent depending on the initial success of fertilization in a given batch, a possible indication that the initial quality of gametes may selectively exert its influence at the later stages of embryo development.     

Animal board invited review: Germplasm technologies for use with poultry

Over the last century, several reproductive biotechnologies beyond the artificial incubation of eggs were developed to improve poultry breeding stocks and conserve their genetic diversity. These include artificial insemination (AI), semen storage, diploid primordial germ cell (PGC) methodologies, and gonad tissue storage and transplantation. Currently, AI is widely used for selection purposes in the poultry industry, in the breeding of turkeys and guinea fowl, and to solve fertility problems in duck interspecies crosses for the production of mule ducklings. The decline in some wild game species has also raised interest in reproductive technologies as a means of increasing the production of fertile eggs, and ultimately the number of birds that can be raised. AI requires viable sperm to be preserved in vitro for either short (fresh) or longer periods (chilling or freezing). Since spermatozoa are the most easily accessed sex cells, they are the cell type most commonly preserved by genetic resource banks. However, the cryopreservation of sperm only preserves half of the genome, and it cannot preserve the W chromosome. For avian species, the problem of preserving oocytes and zygotes may be solved via the cryopreservation and transplantation of PGCs and gonad tissue. The present review describes all these procedures and discusses how combining these different technologies allows poultry populations to be conserved and even rapidly reconstituted.     

Assessment of fresh and stored duck spermatozoa quality via in vitro sperm-egg interaction assay

An in vitro sperm-egg interaction assay was used to measue the quality of duck spermatozoa in fresh and stored semen. The inner perivitelline layer (IPVL), which had been separated from laid duck eggs, was incubated with spermatozoa in vitro. The number of points of sperm hydrolysis in the IPVL in vitro was logarithmically correlated with the fertility of the eggs laid by inseminated females, for both fresh semen (r = 0.85, P < 0.001) and stored semen at 5 degrees C for 24 h (r = 0.84, P < 0.001). After semen storage, the ability of spermatozoa to hydrolyze the IPVL decreased by 67.4% compared with the values for fresh semen, whereas egg fertility and sperm motility decreased by 47.8% and 15.2%, respectively. These results suggest that the in vitro sperm-egg interaction assay accurately reflects the fertilizing ability of fresh and stored duck spermatozoa and detects spermatozoal damage due to semen storage more sensitively than motility or fertility tests.     

Semen characteristics and artificial insemination in rockhopper penguins (Eudyptes chrysocome chrysocome)

This work was performed as part of a multi-year study to determine the cause of the low fertility in captive rockhopper penguins (Eudyptes chrysocome chrysocome) and attempt to increase the fertility through artificial insemination (AI). Semen collection and characterization was performed on 14 male rockhopper penguins. The samples were evaluated for volume, sperm concentration, and sperm quality (motility, forward motility, viability, and morphology). There was a large variation between individuals and between collections for each individual. Mean volume of ejaculate was 0.24 ml. Mean concentration was 47.09 × 10(6) sperm/ml. Mean number of sperm per collection was 6.57 × 10(6). The mean motility was 49.4%. Mean forward motility was 1.7. Mean percentage of living sperm was 88.9%. Mean percentage of sperm with normal morphology was 69.4%. AI was performed on a total of 10 females using pooled semen samples. The birds were also allowed to naturally mate. Ten eggs were laid and three fertile eggs were produced, one of them hatched but died within 24 hr. Paternity testing was performed using 12 microsatellite loci, but unfortunately due to insufficient variability, the paternity of the chick and two embryos could not be determined.     

Effects of semen filtration and dilution rate on morphology and fertility of frozen gander spermatozoa.

Feces, urates or dirt originating from feathers often contaminate gander semen during collection, threatening its fertilizing ability. Seminal plasma used as a diluent has a similar effect, particularly on spermatozoa subjected to cryopreservation or short-term storage under refrigeration. The aim of the experiments was to evaluate the effects on spermatozoa motility, morphology and fertilizing ability after minimizing the influence of the contaminants by semen filtration or dilution prior to freezing. Pooled semen, collected twice a week from 9 White Italian ganders by dorso-abdominal massage, was divided into two parts. One sample was filtered and both were diluted in 1:1 or 1:0.5 (v/v) with EK diluent, equilibrated for 15 min at +4 degrees C, mixed with dimethyl-acetamide (DMA) in the final concentration 6% (v/v) and frozen to -140 degrees C in a computerized freezer, at a rate of 60 degrees C/min. In fresh and processed (filtered, freeze-thawed) semen were examined the spermatozoa motility and morphology, and fertilizing ability for freeze-thawed semen, both for unfiltered and filtered. In freeze-thawed semen no tangible differences due to experimental factors were observed in motility and percent of live spermatozoa in total. On average 35 to 42% of the spermatozoa survived the freezing process, but only 10 to 15% were normal, without any damage visible under the light microscope. The fertility of unfiltered freeze-thawed semen inseminated twice a week in a 0.2 mL dose (about 3 to 5 x 10(6) of live normal spermatozoa each) averaged 66.1% and hatchability of the set eggs 57.1 and 86.5% of the fertile eggs. The fertility obtained after the insemination with semen filtered prior to freezing was lower (64.3%), but hatchability was slightly higher (58.6 and 91.1% of set and fertile eggs, respectively). The duration of fertility for filtered semen was longer than that for unfiltered, 10 days after the last insemination the eggs were still fertile. The fertility results of freeze-thawed gander semen were very promising taking into consideration the small amount of inseminated live normal spermatozoa and it is possible to improve this result by increasing the number of spermatozoa in the insemination dose.     

The possibility of obtaining intergeneric hybrids via White Kołuda (Anser anser L.) goose insemination with fresh and frozen-thawed Canada goose (Branta canadensis L.) gander semen

The objective of the present experiments was to produce the intergeneric hybrids of domesticated and wild goose via artificial insemination with fresh and frozen-thawed semen. The experiments were carried out during two successive goose reproductive seasons, on eight five-year-old Canada Goose (Branta canadensis L.) males used as semen donors and 16 two-year-old White Ko?uda geese designated to fertility tests. Pooled semen was collected twice a week by the dorso-abdominal massage. In freshly collected semen, ejaculate volume, color, consistency, degree of fecal or blood contamination, spermatozoa concentration, motility, and morphology were evaluated. Part of the semen collected in the first year of the experiment (Experiment 1) was used for geese insemination with fresh semen, while the remainder was frozen. In Experiment 2 all samples were subjected exclusively to freezing procedure. Geese were inseminated once a week with fresh semen in a dose of 80 μl or 160 μl, and twice a week with frozen-thawed semen in a dose of 80 μl (160 μl per wk) or 100 μl (200 μl per wk). Eggs were set weekly and incubated up to hatching.The volume of ejaculates varied from 0.100 to 0.470 ml; spermatozoa concentration from 140 to 310 million ml⁻¹; progressive movement was observed in 40 to 60% of spermatozoa; the percentage of total live spermatozoa ranged from 69.3 to 92.0%, the highest percentage (34.0-68.3) was represented by live normal spermatozoa and those with bulb-head (13.3-41.0). Cryopreservation caused a decrease in percentage of motile cells to 30%; total live spermatozoa contribution by 27.2%p, including those live normal by 15.9%p (in relation to the fresh semen), bulb-head spermatozoa by 10.9%p, and increase (by 5.9%p) in number of spermatozoa with other deformations. Goose insemination 1×/week with fresh semen containing about 10.3 million live normal spermatozoa resulted in 66.7% of fertile eggs and with dose higher by 2.8 million spermatozoa (on average) the fertility increased by 20.9%p (up to 87.6% on average). Hatchability from set and fertile eggs was 55.9% and 83.9% vs. 66.3% and 75.6%, respectively. After twice a week insemination with frozen-thawed semen containing about 10.2 million live normal cells 58.2% eggs were fertile; hatchability from set eggs was 42.8% and from fertile eggs 71.7%, while insemination dose increase by 2.7 million spermatozoa per week caused a fertilization increase by 3.8%p (62.0% on average), this increase was not statistically significant, but hatchability from the fertile eggs (95.4%), was significantly (P < 0.05) higher.The use of AI with fresh semen in the creation of intergeneric hybrids of Canada goose males and White Ko?uda females allows a high level of egg fertility to be obtained. Furthermore, one limitation which is the short reproductive season of the Canada goose may be overcome by the use of cryopreserved semen.     

Production of chicken progeny (Gallus gallus domesticus) from interspecies germline chimeric duck (Anas domesticus) by primordial germ cell transfer

The present study aimed to investigate the differentiation of chicken (Gallus gallus domesticus) primordial germ cells (PGCs) in duck (Anas domesticus) gonads. Chimeric ducks were produced by transferring chicken PGCs into duck embryos. Transfer of 200 and 400 PGCs resulted in the detection of a total number of 63.0 ± 54.3 and 116.8 ± 47.1 chicken PGCs in the gonads of 7-day-old duck embryos, respectively. The chimeric rate of ducks prior to hatching was 52.9% and 90.9%, respectively. Chicken germ cells were assessed in the gonad of chimeric ducks with chicken-specific DNA probes. Chicken spermatogonia were detected in the seminiferous tubules of duck testis. Chicken oogonia, primitive and primary follicles, and chicken-derived oocytes were also found in the ovaries of chimeric ducks, indicating that chicken PGCs are able to migrate, proliferate, and differentiate in duck ovaries and participate in the progression of duck ovarian folliculogenesis. Chicken DNA was detected using PCR from the semen of chimeric ducks. A total number of 1057 chicken eggs were laid by Barred Rock hens after they were inseminated with chimeric duck semen, of which four chicken offspring hatched and one chicken embryo did not hatch. Female chimeric ducks were inseminated with chicken semen; however, no fertile eggs were obtained. In conclusion, these results demonstrated that chicken PGCs could interact with duck germinal epithelium and complete spermatogenesis and eventually give rise to functional sperm. The PGC-mediated germline chimera technology may provide a novel system for conserving endangered avian species.     

An effective method for freezing White Italian gander semen

Efficiency of freezing method, worked out for the White Italian gander semen was evaluated by comparing motility, morphology and fertilizing ability of spermatozoa in fresh and frozen-thawed semen. A part of pooled semen, collected from 25 White Italian ganders by dorso-abdominal massage was used immediately for artificial insemination of 10 geese (the control group) with a dose of 80 microl. This insemination was performed six times at weekly intervals. The remainder of the semen was diluted 1:0.5 (v/v) with EK diluent, equilibrated for 15 min at +4 degrees C, mixed with 6% (v/v) of dimethylformamide (DMF) and frozen to -140 degrees C at a rate of 60 degrees C/min. Frozen semen was thawed in a 60 degrees C water-bath and inseminated twice weekly in a dose of 100 microl (10 females of the experimental group, 12 inseminations were made). The freezing process affected spermatozoa motility and morphology, but had no effect on their fertilizing ability. Positive movement was observed in 50-60% of the spermatozoa in fresh semen and about 40% of the frozen-thawed cells. The average percentage of total live and live normal spermatozoa decreased due to freezing from 92.2 to 68.4% and from 34.7 to 14.1%, respectively. After the fresh semen insemination with average 12 million of the live normal spermatozoa per week average fertility was 88.24%; hatchability of set eggs was 80.88% and hatchability of fertile eggs was 91.67%. For frozen-thawed semen inseminated with average 9.5 million of the undamaged spermatozoa per week, the average fertility and hatchability rate was 83.78, 73.87, and 88.17%, respectively. Fecundity rates obtained after insemination with the frozen-thawed gander semen allow for the application of the freezing technique into breeding practice, in place of natural mating or to assist natural mating in periods of lowered fertility level.     

Influence of centrifugation or low extension rates prefreezing on the fertility of ram semen after cervical insemination

We compared the fertility of thawed ram semen, frozen according to different prefreezing semen handling protocols and previously well-defined in vitro, after cervical artificial insemination (AI) during natural estrus in Corriedale sheep. Following primary extension 1 + 1, we adjusted the final sperm concentration before packaging (200 x 10(6)/straw) either by centrifugation, in order to reconcentrate the extended semen (Protocol 1: P1), or without centrifugation, by adjusting the final sperm number by stepwise extension (Protocol 2: P2). We evaluated sperm motility (assessed both subjectively and with a computer-assisted sperm analysis instrument [CASA]), membrane integrity (SYBR-14/PI), and capacitation status (chlortetracycline [CTC]) in vitro in three pooled straws of frozen-thawed semen. Three hundred Corriedale ewes, having shown spontaneous estrus during the breeding season (i.e., April, in the southern hemisphere) under extensive management conditions in Uruguay, were cervically inseminated with thawed semen from the same freezing operations as studied in vitro. The semen evaluation in vitro yielded higher percentages (P < 0.05) of damaged spermatozoa in the samples where sperm numbers were adjusted by extension before freezing (P2), compared with when adjustment was done by centrifugation (P1). However, due to the higher sperm concentration finally achieved by P2, the calculated total number of viable spermatozoa was almost equal in the two AI doses. We observed no differences in fertility between P1 and P2 for either nonreturn rates (NRRs) 21 (30.8 vs. 29.7%) and 36 (28.5 vs. 27.8%) days after AI or lambing rate (21.9 vs. 21.4%), respectively. Fertility did not differ significantly between the two different procedures of adjusting sperm numbers prior to freezing. This may indicate that the simplified protocol with adjusted extension of the semen, resulting in higher numbers of viable spermatozoa, should be the procedure of choice when freezing ram semen under field conditions. Further studies aimed at improving the modified protocol need to be performed.     

Genetic markers for stallion fertility--lessons from humans and mice

Our knowledge on the many aspects of mammalian reproduction in general and equine reproduction in particular has greatly increased during the last 15 years. Advances in the understanding of the physiology, cell biology, and biochemistry of reproduction have facilitated genetic analyses of fertility. Currently, there are more than 200 genes known that are involved in the production of fertile sperm cells. The completion of a number of mammalian genome projects will aid in the investigation of these genes in different species. Great progress has been made in the understanding of genetic aberrations that lead to male infertility. Additionally, the first genetic mechanisms are being discovered that contribute to the quantitative variation of fertility traits in fertile male animals. As artificial insemination (AI) represents a widespread technology in horse breeding, semen quality traits may eventually become an additional selection criterion for breeding stallions. Current research activities try to identify genetic markers that correlate to these semen quality traits. Here, we will review the current state of genetic research in male fertility and offer some perspectives for future research in horses.     

The value of microscopic semen motility assessment at collection for a commercial artificial insemination center, a retrospective study on factors explaining variation in pig fertility

This study was conducted to evaluate the relationship between boar and semen related parameters and the variation in field fertility results. In 8 years time semen insemination doses from 110 186 ejaculates of 7429 boars were merged to fertility parameters of inseminations of 165 000 sows and these records were used for analysis. From all ejaculates boar and semen related data were recorded at the artificial insemination (AI) centers. Fertility parameters, such as farrowing rate (FR), ranging between 80.0% and 84.0%, and the total number of piglets born (TNB), ranging between 12.7 and 13.1, were recorded and from these the least square means per ejaculate were calculated. Only 5.9% of the total variation in FR was due to boar and semen variability of which 21% (P = 0.0001) was explained by genetic line of the boar, 11% (P = 0.047) was explained by laboratory technician, and 7% (P = 0.037) was explained by the AI center. For TNB the total variation was 6.6% boar and semen related of which 28% (P < 0.0001) was explained by genetic line of the boar and 7% (P = 0.011) was explained by the AI center. Only 4% of the boar and semen related variation was caused by sperm motility (microscopically assessed at collection, ranging from 60% to 90%). Other variation in FR and TNB was explained by management and semen related parameters (age of boar, 3%; P = 0.009; and 8%; P = 0.031, respectively), days between ejaculations (1%; P < 0.0001 of FR), number of cells in ejaculate (1%; P = 0.042 of TNB), year (9%; P = 0.032), and 13%; P = 0.0001, respectively), and month (11%; P = 0.0001; and 5%; P = 0.0001, respectively). Although semen motility is considered an important parameter to validate the quality of the ejaculate processed, it only minimally relates to fertility results under the current Dutch AI practice. Other boar and semen related parameters, like genetic line of the boar, are more relevant factors to select boars for AI purposes.     

Seasonal effects of semen collection and artificial insemination on dairy cow conception

The effects of four seasons of semen collection and of artificial insemination on conception in dairy cows were studied. The solstices and equinoxes (December, March, June and September) defined the beginning and/or end of each season. Semen was collected from 973 progeny-test bulls over 8 years at the two Norwegian AI stations at 60.8 degrees N and 63.4 degrees N where artificial light was used to provide a minimum photoperiod of 10 h/day. The effect of using semen of elite bulls during progeny testing and after selection as elite sires also was investigated. Norwegian Red (NRF) cows were inseminated over a 7-year period using progeny test semen and over the last 4 years of the same period using the semen of the elite sires. The probability of conception to only first inseminations for cows up to, and including, the fifth lactation was assessed by 56-day non-return rate (56d NRR) and calving rate. Two data sets were analysed which excluded cows culled within 270 days of AI or included such cows as non-calving. The reasons for culling were categorised as those for fertility problems or all other reasons. Semen was used for AI irrespective of the season in which it had been collected. Season of semen collection did not affect 56d NRR but calving rate was significantly higher (by 0.5-0.8%, approximately; P < 0.01) for semen collected in the December-March period, when photoperiod was increasing, than at other times of the year. The season in which AI was performed showed a peak of 56d NRR in spring for heifers (P < 0.01) and in summer for parous animals (P < 0.01). For calving rate, however, no seasonal peak was found in heifers, whereas pluriparous cows had much higher calving rates in summer and autumn/early winter than late winter and spring (P < 0.01). Semen of elite sires resulted in higher calving rates by 0.5 (NS) to 1.9% (P < 0.01) when used after selection than when used during progeny testing. The difference between the calving rate achieved when the semen from elite sires was used during progeny testing and after selection indicates that farmers select different classes of cows for submission to AI by progeny test bulls and sires. The 56d NRR was not as good as calving rate for assessing seasonal and other effects on conception rates.     

Behavioural and physiological fear responses in ducks: genetic cross effects

Mule duck, a cross between a Muscovy drake and a Pekin female, is reported by the farmers to frequently express fear behaviours, such as man avoidance. The genetic basis of fear responses in mule ducks was therefore investigated in this study. According to a previous experiment, the dominant effect of Pekin genotype was hypothesised; however, due to the absence of birds from the reciprocal cross, a superiority of the Pekin in additive effect could not be distinguished from a direct maternal additive effect. In order to clarify this, ducks from the mule genotype, the two parental genotypes (Pekin and Muscovy) and the reciprocal intercross (hinny) underwent a set of physiological and individual behavioural tests of fear. Both parental genotypes were highly fearful but exhibited responses of different patterns: Pekin ducks manifested a higher locomotor activity, whereas the Muscovy ducks showed a higher avoidance to man. Hybrids expressed higher panic responses and specific fear of man than the two parent breeds. Both hybrids expressed similar patterns and the maternal effects were not significant. Significant heterosis effects were found for most of the behavioural responses, in agreement with the fact that higher fear responses were expressed by the hybrids compared to the parental genotypes. A significant heterosis effect was also found for basal adrenal activity; hybrids having higher basal level than parental genotypes. Maximum capacity of adrenal response appeared to be determined by direct additive effects with a superiority of the Pekin genotype.     

Age effect of broiler breeders on fertility and sperm penetration of the perivitelline layer of the ovum

The objective of this study was to determine the age effect of a broiler breeder flock on duration of fertility and number of spermatozoa penetrating the perivitelline layer overlying the germinal disc (SP/mm(2) GDIPVL). Moreover, in the second half of the flock's reproductive life, the effect of using ejaculates of young roosters (CA2) in artificial insemination (AI) on the above parameters of fertility was estimated. The commercial flock of broiler breeder hens (n = 100) was inseminated six times from 31 to 62 weeks of age. Additional inseminations, with ejaculates of roosters aged 31 and 36 weeks (CA2), were performed at 56 and 62 weeks of age. AI was performed during two consecutive days (D0 and D1) with an insemination dose of 125 x 10(6) spermatozoa/0.06 ml containing pooled ejaculates. The following parameters were studied: the effective and maximum duration of fertility (De and Dm), percent of fertility on different days after AI (FD10, FD15 and FD20), indices of duration of sperm penetration (DSP, SP < or = 3/GDIPVL), SP/mm(2) GDIPVL in eggs laid on successive days after insemination of hens at different age, and correlations between some fertility indices. Both for De and Dm, the highest values were noted after AI of the layers at 36 weeks of age (14.8 +/- 0.49 and 17.4 +/- 0.46 days, respectively), which were about 2 days longer than at 56 weeks. All fertility indices decreased gradually with age, starting from AI at peak egg production (31-36 weeks of age), while the use of ejaculates from CA2 did not help to increase them significantly. Correlation coefficients between SP/mm(2) GDIPVL and the other fertility indices were positive and highest for eggs laid on D3. It is concluded that high De values can be obtained from broiler breeders in adequate environmental and technological conditions of AI. It is suggested that the age-related decrease in fertility is more pronounced in females, in which the efficiency of sperm storage tubules decreases. The present fertility indices indicate the possibility of lengthening AI intervals, especially at peak egg production.     

Implementing artificial insemination as an effective tool for ex situ conservation of endangered avian species

Approximately 503 of the known species of birds are classified as ‘endangered’ or ‘critical’. Captive propagation programs have proven useful in maintaining genetic diversity and restoring wild populations of certain species, including the Peregrine falcon, California condor and Whooping crane. Artificial insemination (AI) has the potential of solving problems inherent to reproductive management of small, closed populations of endangered birds, including dealing with demographic instability, physical and behavioral disabilities, sexual incompatibility, lack of synchrony, and need to maintain gene diversity. In this review, we address the necessary methods and factors that allow AI to be applied effectively to manage rare bird populations. It is clear that semen availability and quality are the greatest limiting factors to implementing consistently successful AI for birds. Behavioral sensitivity to animal handling and the ability to minimize stress in individual birds also are keys to success. Multiple, deep vaginal inseminations can improve fertility, particularly when semen quality is marginal. Laparoscopic methods of semen transfer also have produced fertile eggs. All of these practices leading to successful AI remain dependent on having adequate basic knowledge on female reproductive status, copulatory behavior, endocrine profiles and duration of fertility, especially as related to oviposition. The overall greatest challenge and highest priority is defining these normative traits, which are highly species-specific.     

Does cleansing of frozen-thawed bull semen before assessment provide samples that relate better to potential fertility?

The present study estimated, in vitro, the influence of two cleansing methods on sperm parameters post-thaw and their relation to the fertility of the frozen-thawed semen after AI. Frozen semen from six 1-year-old Swedish Red and White dairy bulls with a range in fertility (as 56d-Non-Return Rates, i.e., 56d-NRR) of 62.2-70.7% among batches was tested, using three batches of semen per bull. From each batch, individual straws were analyzed immediately after thawing (PT, control) or pooled and subjected to a swim-up procedure (SU) or washing by centrifugation/re-suspension (W) prior to in vitro assessments. Subjective and computerized measurements of sperm motility and of concentration, morphology, and membrane integrity were recorded. SU provided spermatozoa with significantly better motility, acrosome-, midpiece- and tail morphology and membrane integrity compared to either control or W treatment. Significant, albeit low, correlations among single sperm parameters and NRR were found (after PT for tail abnormalities (r = 0.49) and average path velocity, VAP (r = 0.47), after SU for total sperm motility with CASA (r = 0.50) and after W only for non-linear motility (r = -0.69)). SU of frozen-thawed bull semen is a simple preparation procedure that selects for sperm motility and membrane integrity, essential parameters for fertilization. It helps in vitro assessment of the semen and provides a significant, although low, relationship to the fertility of the assayed semen.