bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Dry Summer Diminishes Mate Search Effort by Pronghorn Females: Evidence for a Significant Cost of Mate Search
Authors: Byers John A. , Byers Anna A. , Dunn Stacey J. 
Published: January 2006

AbstractIn the 2 weeks before estrus, pronghorn (Antilocapra americana) females on the National Bison Range in northwestern Montana, USA usually move actively among several widely spaced, mature, site‐faithful males in a mate search process that identifies vigorous mates. Typically, at least 90% of females practice this active sampling each year; each of the remaining females moves, before the rut begins, to a peripheral, isolated location with a single male and mates there without sampling. In 2001 and 2002, 90 and 100% of females, respectively, used the sampling strategy. The summer of 2003 was unusually hot and dry in western Montana. By September, when the pronghorn rut occurs, many pronghorn females were in visibly poor condition. In the winter that followed, 38% of females and 79% of males died, and in the following spring, only 17% of the surviving females gave birth. In the rut of 2003, 19% of females practiced the active sampling strategy. In 2004, 68% of females attempted to sample, even though there were only three mature males in the population. Among females that sampled, the number of switches away from harems and the number of males visited did not vary across years, except in 2004. The proportion of samplers in 2003 that died over winter was not different from the proportion of non‐samplers that died over winter, and among the survivors, the proportion of samplers that completed gestation was not different from the proportion of non‐samplers that completed gestation. The data suggest that pronghorn females have a strong motivation to sample potential mates, that sampling is abandoned when energy stores are low, and that yearly variation in the percent of females that sample is explained by variation in female condition.
Mate Choice in Male Mandrills (Mandrillus sphinx)
Authors: Setchell Joanna M. , Jean Wickings E. 
Published: January 2006

AbstractMale primates that attempt to monopolize access to receptive females by mate‐guarding expend time and energy and risk injury, making reproduction costly. Males should therefore show mate choice and preferentially allocate mating effort to females that are likely to be fertile and those that will produce high‐quality offspring. Specifically, males should preferentially mate‐guard high‐ranking females rather than low‐ranking females, as such females are more likely to be fertile and are able to invest more in offspring. Males should also prefer parous females to nullipares, for similar reasons. Finally, males should avoid mating with close relatives, to avoid the deleterious effects of inbreeding. We investigated 13 group‐years of mate‐guarding observations for two semi‐free‐ranging groups of mandrills to examine the influence of these factors on male investment in mate‐guarding. We found that males mate‐guarded higher‐ranking females more than lower‐ranking females, and parous females more than nullipares. Female age, true relatedness and maternal kinship did not influence male mate‐guarding. Our results suggest that male mandrills do exercise mate choice for higher‐quality females, in the form of higher‐ranking and parous females. As alpha males are responsible for the great majority of mate‐guarding, this can lead to assortative mating, where high‐ranking males reproduce with high‐ranking females, and has important implications for social relationships and kin selection.
Phenotypic Plasticity in the Reproductive Behavior of Female Sand Tilefish, Malacanthus plumieri
Authors: Baird Troy A. , Baird Teresa D. 
Published: January 2006

AbstractFemale sand tilefish (Malacanthus plumieri) inhabiting a deep channel in the fringing reef at Glover's Atoll, Belize (channel females) spawned planktonic eggs more frequently than those occupying the shallow sand‐rubble slopes adjacent to patch coral reefs inside the atoll lagoon (reef‐slope females). We tested five non‐exclusive hypotheses to explain habitat differences in female spawning frequency. We found no evidence that spawning frequency variation was a consequence of differences in food availability, variation in male fertility, or the intensity of predation on spawned eggs. On reef slopes, barracuda stalked tilefish near their benthic burrows, whereas these piscivores attacked channel tilefish by diving suddenly from higher in the water column. Differences in the hunting behavior of barracuda suggested that the behavior of tilefish females might be influenced by temporal variation in predation risk (risk allocation hypothesis). Consistent with this hypothesis, reef‐slope females had a much higher frequency of retreats to burrows in response to barracuda, spent more time burrowing and ventured less far from these refugia in response to a simulated predatory threat. As predicted by the risk allocation hypothesis, reef‐slope females also had lower and more variable frequencies of foraging bites, and shorter and more variable travel distances to forage than channel females. Estimated mortality from predation was over nine times higher in channel tilefish. Consistent with the hypothesis that investment in current vs. future reproduction is influenced by rates of adult mortality (mortality risk hypothesis), channel females invested more supplemental energy in egg production whereas reef‐slope females invested more in growth. Our results indicate that behavioral and life‐history traits of female tilefish show phenotypic plasticity depending upon the nature and intensity of localized predation risk.
The Effect of Social Environment on Male–Male Competition in Guppies (Poecilia reticulata)
Authors: Price Anna C. , Helen Rodd F. 
Published: January 2006

AbstractWe examined male–male competition in guppies (Poecilia reticulata) to test for evidence of hierarchy formation and any subsequent effects on male mating success by comparing the interactions of pairs of males that were siblings and life‐long tank mates with those of unrelated pairs that had never met. These pairs of males were first observed in the absence of a female; then a female was added to gauge the effects of the initial male–male interactions on male sexual behaviour. The unfamiliar/unrelated pairs engaged in significantly more aggressive interactions such as physical contacts, nipping and chasing than the familiar/related pairs. Based on several previous studies, we suggest that familiarity played a greater role than relatedness in the differences in behaviour that we observed. Our results suggest that, in some circumstances, more aggressive males may have more mating opportunities than less aggressive males. Our results also indicate that males adjust their aggressive and courtship behaviours to the perceived intensity of competition for mates, based on the number of mature males in their rearing tanks. We suggest that male–male competition for mating opportunities may play a more important role in the guppy mating system than previously thought.
Reproductive and Endocrine Characteristics of Delayed Pubertal Ewe‐Lambs after Melatonin and l‐Tyrosine Administration
Authors: El‐Battawy KA 
Published: January 2006

ContentsThe investigation was carried out to study the impact of melatonin and l‐tyrosine administration on the onset of cyclicity in delayed pubertal ewe‐lambs. Fifteen delayed pubertal ewe‐lambs (age >16 months) were used in this study after being assigned randomly into three groups. In the first group (melatonin treated group, n = 5), each lamb was administered 3 mg melatonin orally at 16:00 hours from 1 July to 15 September while in the second group (l‐tyrosine treated group, n = 5), each lamb was administered l‐tyrosine at the level of 100 mg/kg b.w. as a single oral dose. The third group (n = 4) served as control. Lambs were exposed to mature, fertile rams daily and blood samples were collected twice weekly. The progesterone concentrations (P4 evaluations) were significantly higher (p < 0.05) in treated groups than the control group. Ovarian activity, assessed by P4 evaluations, showed that all animals in the first group came in oestrus and from them four got pregnant (80%) while in the second group, only three lambs came in heat and from them two became pregnant (40%). On the contrary, none of the control lambs showed oestrus. In conclusion, this study confirmed that the oral administration of melatonin and l‐tyrosine played an essentially physiological roles to induce cyclicity in delayed pubertal ewe‐lambs and improved their reproduction.
Normal Values for the Scrotal Circumference in Rams of Gotlandic Breed
Authors: Söderquist L , Hultén F 
Published: January 2006

ContentsSelection of fertile sires is crucial for profitable lamb production. Males with larger testes tend to sire daughters that reach puberty at an earlier age and ovulate more ova during each oestrus period. Measurement of the scrotal circumference (SC) is thus an essential part of the breeding soundness evaluation. Testicular size varies with breed, age and time of the year. No SC values or recommendations for minimal values have been established in any of the Scandinavian domestic sheep breeds. Data were recorded of the SC, age and weight in 245 ram lambs and 27 mature rams of the Gotlandic breed, which is the breed that constitutes about 50% of the Swedish sheep population. For the ram lambs, the overall mean SC was 28.9 (±1.9) cm at an average age of 170 (±9) days and mean weight of 53.5 (±7.0) kg, and the mean SC varied between 27.1 and 29.6 cm depending on age and weight. For mature rams (17–54 month old), the mean SC was 32.4(±2) cm. To provide a practical tool for exclusion of rams with sub‐optimal reproductive capacity (abnormal testes or those with small testes because of delayed puberty) a threshold value was established based on the average SC minus 2 SD. The calculated minimal SC is 26 cm for ram lambs >5.5 months of age with a body weight of >50 kg. For mature rams, minimum SC is 28 cm regardless of weight and age.
Mitochondrial Activity, Distribution and Segregation in Bovine Oocytes and in Embryos Produced in Vitro
Authors: Tarazona AM , Rodríguez JI , Restrepo LF , Olivera‐Angel M 
Published: January 2006

ContentsBovine oocytes and embryos produced in vitro were studied to determine the mitochondrial pattern of distribution, segregation and activity using DIOC 6 and Jc‐1 fluorescence. The highest fluorescence level observed in mature oocytes was taken as 100% activity and six activity levels were estimated as follows: (1) 0%, (2) 1–15%, (3) 16–30%, (4) 31–50%, (5) 51–75% and (6) 76–100%. Three patterns of mitochondrial distribution were found: (1) diffused throughout the cytoplasm in oocytes and embryos, (2) pericytoplasmic in oocytes and embryos, and (3) perinuclear only in embryos. The segregation of mitochondria in blastomeres showed two distinct patterns: (1) symmetrical with an even mitochondrial population, and (2) asymmetrical with different numbers of mitochondria in each blastomere. In immature oocytes, mitochondrial activity was very low and the distribution was diffuse or negligible, while in mature oocytes the activity was high and the distribution was diffuse or pericytoplasmic. Competent embryos up to the 16‐cell stage showed intermediate levels of activity (16–50%) but activity decreased thereafter up to the blastocyst stage. Non‐competent embryos showed low levels of activity (1–15%) at all stages. These results suggest that mitochondria might play an important role during early development and that a minimum threshold of activity regulates the potential competence for reaching the blastocyst stage.
Update on Semen Technologies for Animal Breeding*
Authors: Morrell JM 
Published: January 2006

ContentsDespite the scale of the livestock breeding industry, where many millions of insemination doses are prepared each year, sperm preparation techniques are used infrequently in animal assisted reproduction compared with its human counterpart. However, some of the techniques used for human sperm preparation, for example, density gradient centrifugation, improve the quality of sperm preparations which is, in turn, reflected by an increased conception rate. The preparation technique separates motile spermatozoa with normal morphology and intact DNA from the total sperm population, leaving behind immature or senescent spermatozoa, morphologically abnormal ones and those with damaged DNA. Furthermore, the motile spermatozoa are removed from the seminal plasma which carries cells, cellular debris and reactive oxygen species, as well as pathogens. Gradient‐prepared spermatozoa survive longer, either in liquid storage or when cryopreserved, and are free of bacteria and viral infectivity if prepared carefully. Preparation techniques such as density gradient centrifugation, or the simplified single layer centrifugation technique, have considerable potential for aiding sperm preparation from poor quality semen samples, such as may be obtained from unselected semen donors in captive breeding programmes, or from performance horses. Moreover, the removal of pathogens has important implications, both for disease control and for avoiding the use of antibiotics in semen extenders, which can be detrimental to sperm survival.
Studies on the Effect of Supplementing Boar Semen Cryopreservation Media with Different Avian Egg Yolk Types on in Vitro Post‐thaw Sperm Quality
Authors: Bathgate R , Maxwell WMC , Evans G 
Published: January 2006

ContentsFertility after insemination of cryopreserved boar semen is currently below that of fresh semen. In an attempt to improve the post‐thaw motility and acrosome integrity of boar sperm, semen was frozen using an adapted Westendorf method in which the chicken egg yolk was replaced by either duck or quail egg yolk. The different composition of the yolk types, particularly the amount of cholesterol, fatty acids and phospholipids, were thought to potentially afford a greater level of protection to sperm against damage during freezing and thawing. Sperm frozen in medium containing chicken egg yolk displayed higher motility immediately after thawing, but there was no difference in the motility of sperm frozen with different types of egg yolk 3 or 6 h after thawing and maintenance at 37°C. Sperm frozen in media containing chicken or duck egg yolk had a higher proportion of intact acrosomes immediately after thawing than sperm frozen in medium containing quail egg yolk, but 6 h after thawing and maintenance at 37°C the sperm that had been frozen in medium containing chicken egg yolk had a higher proportion of intact acrosomes than the sperm frozen in media containing duck or quail egg yolk. Analysis of the composition of the different yolk types showed that the basic components of the yolks were similar, but the ratios of fatty acids and phospholipid classes differed. Duck egg yolk had more monounsaturated fatty acids (MUFA) than chicken egg yolk, which had more MUFA than quail egg yolk. Duck egg yolk contained more phosphotidylinositol (PI) than chicken or quail egg yolks and quail egg yolk contained more phosphotidylserine than either chicken or duck egg yolks. The differences in post‐thaw motility and acrosome integrity of boar sperm when frozen in media containing the different types of egg yolk may be due to the variation in composition.
Influence of Temperature during Glycerol Addition and Post‐thaw Dilution on the Quality of Canine Frozen Semen
Authors: Silva AR , Cardoso RCS , Silva LDM 
Published: January 2006

ContentsThe aim of the present study was to compare the influence of room temperature (27°C) and 4°C during glycerol addition on canine semen cryopreservation and verify the effect of different post‐thawing dilutions on canine semen. Ten ejaculates from five stud dogs were collected by digital manipulation. Semen samples were evaluated and further divided into two aliquots. The first aliquot was extended in Tris‐egg yolk‐glycerol at 27°C and the second one received glycerol at 4°C. Samples were frozen and stored in liquid nitrogen. After 1 week, samples were thawed and submitted to evaluations of progressive sperm motility, morphology, acrosomal integrity, hypo‐osmotic swelling (HOST) and thermoresistance tests. For thermoresistance test, aliquots were divided in two portions: one portion was kept undiluted (1 : 0) and the other one was diluted in a 1 : 4 ratio (one part semen to four parts extender). No differences were observed between temperatures for glycerol addition regarding seminal parameters evaluated. Furthermore, post‐thawing dilutions demonstrated similar effect on canine semen longevity. Correlations among post‐thaw sperm motility and HOST and results from thermoresistance test were observed for both temperatures for glycerol addition. In conclusion, glycerol could be added to canine semen at room temperature (27°C) or at 4°C. Moreover, there is no need to extend canine semen after thawing for the thermoresistance test, but if we need to increase the inseminating volume for artificial inseminations, the addition of extender will not damage the semen.
Effects of β‐OH Butyrate on Bovine Granulosa and Theca Cell Function in Vitro
Authors: Vanholder T , Leroy JLMR , Van Soom A , Coryn M , de Kruif A , Opsomer G 
Published: January 2006

ContentsIn this study, the effects of β‐OH butyrate (BHB) levels, associated with a negative energy balance, on bovine granulosa and theca cell function were investigated in vitro. Granulosa and theca cells of healthy large follicles (>8 mm), obtained from slaughterhouse ovaries, were cultured in serum free medium containing 0, 0.5, 1 or 1.5 mm BHB and 3 mm glucose, to mimic the situation in the early postpartum dairy cow. Hormone concentrations (progesterone, oestradiol‐17β and/or androstenedione) in spent medium and cell numbers were measured after 48 h of culture. No effects of BHB on theca cell numbers or on steroid production were observed. In granulosa cells, all BHB treatments evenly increased cell numbers (p < 0.05), while they reduced progesterone and oestradiol‐17β production per cell (p < 0.05). These effects may be attributed to the use of BHB as energy source which is however differently metabolized than glucose. Conclusively, in the presence of physiological glucose concentrations BHB can modulate granulosa but not theca cell function in vitro.
Incidence of Unilateral Fertilizations after Low Dose Deep Intrauterine Insemination in Spontaneously Ovulating Sows under Field Conditions
Authors: Martinez EA , Vazquez JM , Parrilla I , Cuello C , Gil MA , Rodriguez‐Martinez H , Roca J , Vazquez JL 
Published: January 2006

ContentsA new procedure for non‐surgical deep intrauterine insemination (DUI) in unrestrained sows hormonally induced to ovulate, has been reported. In comparison with standard artificial insemination (AI), with this procedure, the sperm numbers inseminated can be reduced 20‐fold without reducing the reproductive performance of these hormonally treated sows. The present study evaluated, using two experiments, the reproductive performance applying 20‐fold different sperm numbers per AI dose using DUI or standard AI in spontaneously ovulating sows, under field conditions. In experiment 1, AI was applied to crossbred sows at 12, 24 and 36 h after onset of spontaneous oestrus using one of the following two regimes: (i) DUI (treatment) with 0.15 × 109 fresh boar spermatozoa in 5 ml of Beltsville thawing solution (BTS) extender (n = 95), and (ii) standard cervical AI (control) with 2.85 × 109 fresh spermatozoa in 95 ml of BTS extender (n = 95). The farrowing rates of the two groups of sows were statistically similar (NS). However, a decrease (p < 0.002) in litter size and the total number of pigs born alive was observed in sows inseminated with the DUI procedure. In experiment 2, 42 post‐weaned oestrus sows were inseminated following the same design described for experiment 1 during spontaneous oestrus. On day 6 after onset of oestrus, the proximal segment of the uterine horns of the sows were flushed under surgery to retrieve eventual embryos and evaluate the success of fertilization per cornua (e.g. occurrence of effective uni‐ vs bilateral sperm transport rendering uni‐ or bilateral, complete or partial fertilization). Retrieved embryos were assessed for cleavage and number of accessory spermatozoa. Although identical overall pregnancy rates were achieved in both insemination groups, the percentage of sows with partial bilateral fertilization and unilateral fertilization was markedly higher (p < 0.05) in the DUI group (35%) compared with the control (standard AI) group (5%), with a consequent lower (p < 0.001) percentage of viable early embryos after DUI. The number of accessory spermatozoa in the zona pellucida of the embryos was highly variable, but higher (p < 0.001) in control animals than in DUI‐AI. No accessory spermatozoa were found in oocytes retrieved from sows depicting unilateral fertilization. In conclusion, DUI in spontaneously ovulating sows with 0.15 × 109 spermatozoa renders similar farrowing rates but a lower litter size compared with use of standard AI with a 20‐fold higher sperm dose. The lower litter size ought to be related to a decreased distribution of spermatozoa after DUI leading to a higher incidence of partial bilateral and unilateral fertilization.
A Screening for the Occurrence of Autoreactive Antibodies in Sera of Pregnant and Non‐pregnant Bitches
Authors: Schäfer‐Somi S , Herkner KR , Neubauer S , Egerbacher M , Patzl M , Pollak S , Ali Aksoy O , Beceriklisoy HB , Kanca H , Findik M , Kalender H , Aslan S 
Published: January 2006

ContentsSera of healthy pregnant (group I, n = 11) and non‐pregnant (group II, n = 11) bitches were screened for autoantibodies (AAb). In both groups, blood samples were drawn every fifth day between days 5 and 55 after mating. Serum was analysed via indirect immunofluorescence (IIF) with the Canine ANA HEp‐2 Screening Kit®. In all animals, anticytoplasmic AAb were detected. Utilizing primate‐heart substrate slides AAb against contractile proteins of the cytoplasm could be observed. The predominating fluorescence pattern in pregnant animals resembled above all desmin, which was proven via Western blot. The sera were then pre‐incubated with tropomyosin, actin, vimentin, vinculin and keratin solutions, and assessed on HEp‐2 slides and on human and canine fibroblasts as well. The latter substrate was used to verify whether the detected Ab were in fact AAb. Utilizing tropomyosin, revealed elimination of the cytoplasmic fluorescences on all three substrates. It is therefore assumed, that in sera of healthy dogs, AAb against contractile structure proteins of the cytoplasm are present regularly. The majority of pregnant bitches presented with higher end‐point titres (EPT), than to be found in non‐pregnant dogs. AAb against desmin played the key role in those patterns. In addition, sera were screened for thyroid specific AAb, namely thyroglobulin, thyroid peroxidase (TPO), T3and T4, and for AAb against insulin by ELISA or Western blot (TPO). Only in two of the pregnant bitches a weak positive reaction (1 : 100) for T3‐AAb was detected.