Induction of lactational estrus in organic piglet production

The longer lactation period required in organic piglet producing herds reduces the potential number of produced litters per sow per year compared with that of conventional production. Induction and use of lactational estrus may be a way to increase the productivity in organic production. However, if lactational estrus is to be beneficial under practical husbandry conditions, it is crucial that the majority of sows are successfully mated within a few days to make batch farrowing procedures possible. The objective of this study was to investigate the occurrence and timing of lactational estrus in an organic outdoor system based on ad libitum feeding, individual housing until Day 35 in lactation, followed by grouping and introduction of a boar and weaning of piglets after 8 wk. Five groups with four sows ((Danish Yorkshire × Danish Landrace) × Danish Duroc) in each were observed, and rank was determined by a food competition test. All sows showed lactational estrus, and 84% of these sows showed estrus within 1 wk, on average 43.5 d and 7.3 d after farrowing and boar introduction, respectively. The number of days from boar introduction to estrus increased significantly with increasing feed competition rank (the lowest number being the top rank position). Eighty-four percent of all sows were diagnosed pregnant 5 wk after estrus. Behavioral observations revealed that the average total number of copulations per estrus sow was 2.3 with a range of 0 to 5 copulations. The findings of the current study indicate that it is possible to combine lactational estrus and batch farrowing procedures to increase the number of weaned piglets per year per sow in organic piglet production based on 8 wk of lactation or more.     

Induction of lactational estrus in organic piglet production

The longer lactation period required in organic piglet producing herds reduces the potential number of produced litters per sow per year compared with that of conventional production. Induction and use of lactational estrus may be a way to increase the productivity in organic production. However, if lactational estrus is to be beneficial under practical husbandry conditions, it is crucial that the majority of sows are successfully mated within a few days to make batch farrowing procedures possible. The objective of this study was to investigate the occurrence and timing of lactational estrus in an organic outdoor system based on ad libitum feeding, individual housing until Day 35 in lactation, followed by grouping and introduction of a boar and weaning of piglets after 8 wk. Five groups with four sows ((Danish Yorkshire × Danish Landrace) × Danish Duroc) in each were observed, and rank was determined by a food competition test. All sows showed lactational estrus, and 84% of these sows showed estrus within 1 wk, on average 43.5 d and 7.3 d after farrowing and boar introduction, respectively. The number of days from boar introduction to estrus increased significantly with increasing feed competition rank (the lowest number being the top rank position). Eighty-four percent of all sows were diagnosed pregnant 5 wk after estrus. Behavioral observations revealed that the average total number of copulations per estrus sow was 2.3 with a range of 0 to 5 copulations. The findings of the current study indicate that it is possible to combine lactational estrus and batch farrowing procedures to increase the number of weaned piglets per year per sow in organic piglet production based on 8 wk of lactation or more.     

圈养猞猁多雄交配雄性的成功繁殖

研究了笼养猞猁多雄交配的结果以及雄性的成功繁殖。雄兽与发情雌兽随机配对,其繁殖成功(所产生的后代数量)不取决于与雌兽的交配顺序、交配次数与持续时间、遗传关系或雄兽的行为特征,但似乎取决于精子质量,特别是取决于形态正常精子的百分率。繁殖成功的雄兽比其竞争对手具有更多的形态正常的精子,似乎更能成功地诱发交配雌兽的排卵。证实了4窝(占总窝数的20%)幼兽的双重父亲身份。在所有情形下, 2雄1雌的交配间隔为24h 。     

Effects of boar contact and housing conditions on estrus expression in sows

In this paper, the authors review the effects of boar contact and different components of boar presence on onset and expression of estrus in weaned sows. Evidence is presented that boar contact may influence LH release, onset of follicle development and timing of ovulation after weaning. Once the sow is in estrus it is important that she shows estrous behavior, because her expression of estrus determines whether she will be inseminated. Boar contact or components thereof affect expression of estrus in sows. There are distinct differences between different components of boar contact in their effectiveness in the induction of estrous behavior (standing response) in sows. Habituation to boars (due to frequency of boar contact or housing of boars near sows) also affects estrus expression in sows. It is important to inseminate sows at the correct moment relative to ovulation. The use of different estrus detection protocols (e.g., by giving sows different levels of boar stimuli during estrus detection) may result in the definition of distinct periods of estrus that may help to predict the moment of ovulation. However, results to date are not very encouraging. Besides boar stimuli, the housing conditions of sows may affect onset of estrus and estrus expression. This paper focuses on social sow-to-sow interactions. The effects of group housing (as compared to individual housing) on onset of estrus and expression of estrus are equivocal. These effects likely depend on factors like aggression between pen mates, reproductive status of pen mates and social rank of sows within the group.     

Mating patterns of a sphragis-bearing butterfly,Luehdorfia japonica leech (Lepidoptera: Papilionidae), with descriptions of mating behavior

Mating frequency of both sexes in a natural population of the papilionid butterfly Luehdorfia japonica was studied with special attention to the role of sphragis in preventing multiple matings by females. Males patrolled continuously within a patchy habitat throughout the warm daylight period in search for females. Mating took place without specialized courtship behavior. Males also attempted to copulate forcibly with previously mated females, but the presence of sphragis and/or the escape reaction of females prevented copulation. There was no specialized mate rejection behavior. Females mated early in their adult life, mainly on the day of emergence, and the frequency of mated females reached 100% within the first two or three weeks of their flight period. Spermatophore counts based on dissections of wild females possessing a sphragis indicated that they had never remated. Males were sexually active throughout their adult life. Male mating frequency was estimated from an index of scale-loss from the claspers and frequencies of males which had not mated, and those which had mated once, twice or three or more times were respectively estimated to be 33.7%, 40.3%, 18.2% and 7.8%.     

Influence of male mating history on female reproductive success among monandrous Naryciinae (Lepidoptera: Psychidae)

1. Multiple male copulations can have detrimental effects on female fitness due to sperm limitation. 2. Monandrous Naryciinae females are immobile while the males are short‐lived and do not feed. Multiple male mating is therefore expected to lead to sperm limitation in females. Sperm limitation and male limitation are hypothesised as causes of the repeated evolution of parthenogenetic reproduction in the Psychidae. 3. In this study, the effects of multiple male mating on female reproduction are investigated in several species of Naryciinae by allowing males multiple copulations. The results for two species, Siederia listerella and Dahlica lichenella, are compared. The sex ratios of 53 natural populations are examined for indications of male limitation. 4. Previous copulations by the male increased the female's risk of remaining unfertilised. However, contrary to expectations, those unfertilised females were capable of successful re‐mating. 5. In S. listerella, the number of previous copulations of males negatively influenced female fitness. Females produced 30% fewer offspring if they mated with a previously mated male. In D. lichenella, the older the male and the lower its number of total lifetime copulations, the higher the female's reproductive success. 6. Only a fraction of the investigated populations had a female‐skewed sex ratio, but differences in development time between males and females could lead to reproductive asynchrony. 7. In conclusion, male mating history did not lead to strong sperm limitation in Naryciinae as had been suggested by their life history.     

Libido and mating behavior in bulls, boars and rams. A review

In this restricted review of the literature on libido and mating behavior in bulls, boars and rams it is assumed that libido and mating ability are important traits which can affect production significantly in food and fibre producing animals. These traits are strongly influenced by genetic factors, they vary widely in their expression among individuals and they can be reliably assessed or measured. Rearing young post-puberal males in all-bachelor groups can delay or inhibit the subsequent expression of heterosexual mating behavior. In the species reviewed, females adopt the major role in seeking sexual partners. Visual cues are of greater importance than olfactory cues in eliciting male sexual response. Bulls and rams rend to distribute their services among receptive females within their genetic limitations with females newly in estrus being most attractive to the males. Social interactions among males in multi-sire groups can markedly influence the reproductive performance of both individual males and the female herd or flock. Single sire breeding, while potentially more efficient than multi-sire breeding, is dependent upon the reproductive capabilities of the sire. Proper assessment of factors such as libido and mating ability before breeding can greatly reduce the possibility of poor reproductive performance from single sires.     

Mating with sperm-depleted males does not increase female mating frequency in the parasitoid Lariophagus distinguendus

Sexual conflicts due to divergent male and female interests in reproduction are common in parasitic Hymenoptera. The majority of parasitoid females are monandrous, whereas males are able to mate repeatedly. Thus, accepting only a single mate might be costly when females mate with a sperm‐depleted male, which may not transfer a sufficient amount of sperm. In the present study, we investigated the reproductive performance in the parasitoid Lariophagus distinguendus Först. (Hymenoptera: Pteromalidae) and studied whether mating with experimentally sperm‐depleted males increases the tendency of females to remate. Males were able to mate with up to 17 females offered in rapid succession within a 10‐h test period. The resulting female offspring, as an indirect measure of sperm transfer, remained constant during the first six matings and then decreased successively with increasing number of copulations by the males. Experimentally sperm‐depleted males continued to mate even if they transferred only small amounts or no sperm at all. Unlike males, the majority of females mated only once during a 192‐h test period. A second copulation was observed only in a few cases (maximum 16%). The frequency of remating was not influenced by the mating status of the first male the females had copulated with, suggesting that these events are not controlled by sperm deficiency of the females. Furthermore, we investigated male courtship behaviour towards mated females. Male courtship intensity towards mated females decreased with increasing time. However, females that had mated with an experimentally sperm‐depleted male did not elicit stronger or longer‐lasting behavioural responses in courting males than those that had mated with a virgin male. As the observed behaviours in L. distinguendus are known to be elicited by a courtship pheromone, these results suggest that females no longer invest in pheromone biosynthesis after mating (as indicated by ceasing behavioural responses of courting males), irrespective of whether they have received a sufficient amount of sperm or not. We discuss the results with respect to a possible mating strategy of sperm‐depleted males.     

Gilt development and mating in commercial swine herds with varying reproductive performance

The primary objectives were to improve standard operating procedures for gilt development and mating, based on a comparison of practices among commercial Japanese herds with varying reproductive performance. Questionnaires were sent to 115 herds; the 96 herds (83.5%) responding were classified, on the basis of the upper and lower 25th percentiles of pigs weaned per mated female per year, into high-, intermediate- or low-performing herds. During gilt development, high-performing herds switched to a gilt developer diet at an earlier age than low-performing herds (P < 0.05). More high-performing herds performed first insemination “immediately,” with second insemination “6 to 12 h” after first estrus detection than low-performing herds (P < 0.05). However, there were no differences (P > 0.05) among productivity groups with regard to the use of nutritional flushing or percentage of AI used. In multilevel analyses (17,582 service records), gilts in herds using direct boar contact were 13.73 d younger at first mating than those in the herds using indirect boar contact (P < 0.05), but age was not related to feeding practices or the number of days of boar contact per week (P > 0.05). First-serviced gilts in the herds that performed first insemination “immediately” after first estrus detection had an 8.3 to 8.4% higher farrowing rate (FR) than those in herds that performed first insemination at “6 to 12 h” and “24 h” (P < 0.01). Reserviced gilts in the herds with first insemination “immediately” after first estrus detection had 7.5% higher FR than those in herds with first insemination at “6 to 12 h” (P < 0.05). Meanwhile, first-serviced and reserviced gilts in herds that restricted feed after insemination had 0.23 and 0.17 more pigs born alive (PBA) than gilts in the herds that did not restrict feed (P < 0.05). However, PBA was not related to time of insemination (P > 0.05). In conclusion, to improve gilt reproductive performance, we recommend stimulating gilt estrus by using direct boar contact, performing first insemination “immediately” after first estrus detection, and restricting feed intake after insemination.     

Female mating status affects male mating tactic expression in the wolf spider Rabidosa punctulata

Males and females have conflicting interests on the frequency and outcomes of mating interactions. Males maximize their fitness by mating with as many females as possible, whereas choosy females often reduce receptivity following copulation. Alternative male mating tactics can be adaptive in their expression to a variety of mating contexts, including interactions with a relatively unreceptive mated female. Male Rabidosa punctulata wolf spiders can adopt distinctive mating tactics when interacting with a female, a complex courtship display, and/or a more coercive direct mount tactic that often involves grappling with females for copulation. In this study, we set up female mating treatments with initial trials and then paired mated and unmated females with males to observe both female remating frequencies and the male mating tactics used during the interactions. Males adopted different mating tactics depending on the mating status of the female they were paired with. Males were more likely to adopt a direct mount tactic with already-mated females and courtship with unmated females. Already-mated females were considerably less receptive to males during experimental trials, although they did remate 34% of the time, the majority of which were with males using a direct mount tactic. Whereas males adjusting to these contextual cues were able to gain more copulations, the observation of multiple mating in female R. punctulata introduces the potential for sperm competition. We discuss this sexual conflict in terms of the fitness consequences of these mating outcomes for both males and females.     

Effect of boar contact on follicular development and on estrus expression after weaning in primiparous sows

Boar contact can induce ovarian activity, advance estrus and stimulate estrous behavior in sows. High amounts of boar contact can, however, suppress estrous behaviour. The present study with primiparous sows was designed to compare sows that had contact with a teaser boar during detection of estrus, with sows that had no boar contact at all. Number of sows detected in estrus within 9 d after weaning, onset and duration of estrus, follicular dynamics and timing of ovulation were studied. Boar contact increased the number of sows that ovulated and showed estrus from 14 of 47 to 24 of 47 (P < 0.05). Average timing of ovulation was later for sows with boar contact (165 h vs 150 h after weaning). Duration of estrus, detected without a boar, was similar in the two groups. For the sows with boar contact, duration of estrus detected with a boar was longer than estrus detected without a boar (56 vs 38 h; P < .01). Follicular dynamics were not affected by boar contact; boar contact only increased the number of sows with ovulation. Ovulatory sows showed a larger increase in follicular diameter (P < 0.01) from weaning to Day 4 after weaning (from 2.3 to 5.4 mm) than anovulatory sows (from 2.5 to 4 mm). Anovulatory sows did not show follicular growth after Day 4. It is concluded that boar contact can increase the number of sows that ovulate and show estrus after weaning. Estrous behavior does not seem to be suppressed by contact with a teaser boar, compared to sows without boar contact.     

Dual reproductive cost of aging in male Medflies: dramatic decrease in mating competitiveness and gradual reduction in mating performance

Although age-based effects on the reproductive success of males have been reported in several animal taxa the cost of aging on male mating success in lekking species has not been fully explored. We used the Mediterranean fruit fly, a lekking species, to investigate possible cost of aging on male reproductive success. We performed no choice and choice mating tests to test the hypothesis that aging does not affect the mating performance (mating success in conditions lacking competition) or the mating competitiveness (mating success against younger rivals) of males. The mating probability of older males decreased significantly when competing with younger males. Aging gradually reduced the mating performance of males but older males were still accepted as mating partners in conditions lacking competition. Therefore, older males are capable of performing the complete repertoire of sexual performance but fail to be chosen by females in the presence of young rivals. Older males achieved shorter copulations than younger ones, and female readiness to mate was negatively affected by male age. Older and younger males transferred similar amount of spermatozoids to female spermathecae. Females stored spermatozoids asymmetrically in the two spermathecae regardless the age of their mating partner. Aging positively affected the amount of spermatozoids in testes of both mated and nonmated males. No significant differences were observed on the amount of spermatozoids between mated and nonmated males.     

Peripheral plasma testosterone concentration and sexual behavior in young prenatally stressed boars

The purpose of this study was to examine the effects of stress induced physiological changes in the gestating sow on postnatal sexual and endocrine development of male offspring. Ten boars, ranging from 160 to 185 days of age, were randomly chosen from sows which had been maintained under either stress or control conditions during mid-gestation. Blood samples were collected weekly from each boar (minimum of four weeks) at 30 min intervals over a common six-hour period via an indwelling anterior vena cava cannula. Plasma testosterone concentrations were determined by radioimmunoassay. In order to ascertain degree of sexual behavior, boars were exposed weekly to gilts in estrus and a subjective score assigned. No differences (P>.10) were found between prenatally stressed and control boars in overall mean testosterone concentration or libido score. A significant (P<.05) decrease in plasma testosterone concentration was detected in boars over age. Results suggest that mid-gestational stress of gestating sows does not affect the testosterone concentration or sexual behavior of boar off-spring.     

The effects of two oestrus detection procedures and intense boar stimulation near the time of oestrus on mating efficiency of the female pig

In the first experiment, a higher oestrus detection rate (percentage of cycling gilts that were detected in oestrus) and a higher mating rate (percentage of cycling gilts that were mated) were achieved when cycling gilts were checked for oestrus in the corridor adjacent to the boar pens than when they were checked in their own pens, which were separated from the boar pens by a 1.0 m-wide corridor (90 v. 52% and 87 v. 52%, respectively). In the second experiment, several housing treatments were imposed over a 21-day period. A lower proportion of gilts were detected in the I stage of oestrus (positive response to the back-pressure test both in the presence and absence of a boar) and a lower mating rate was achieved when cycling gilts were separated from the boar by a wire-mesh pen division than when separated by a 1.0 m corridor (48 v. 81% and 47 v. 81%, respectively). It was concluded that cycling females should be housed near, but not adjacent to, boars and that at the time of oestrus detection using the back-pressure test, females should be very close to boars.     

The influence of conditions at the time of mating on reproduction of commercial pigs

The objective of this study was to compare a new mating system, called the Detection-Mating Area (DM Area), and a conventional mating system on the long-term reproductive performance of commercial pigs. The DM Area treatment basically involved detecting oestrous females in an arena closely surrounded on two sides by boars and mating these females in this arena. This mating system was designed to improve the physical and sexual environments of the pigs at mating. In contrast, the conventional treatment involved conducting oestrus detection and mating in the boar's accommodation pen. The study was conducted over an 18-month period at a commercial farm that housed 2400 breeding female pigs.

In order to control for the effects of the stockperson, an analysis was conducted on the reproductive performance of female pigs in which one stockperson assisted the matings in both treatments over a 12-month period. Gilts mated in the DM Area treatment had a higher (P<0.05) total litter size and a higher (P<0.01) litter size born alive than gilts mated in the conventional treatment (10.31 vs. 8.96 and 9.50 vs. 8.29, respectively). Although gilts in the DM Area treatment had a higher farrowing rate (93.2 vs. 87.9%), this difference was not significant (P>0.05). There were no significant (P>0.05) differences found between the reproductive performance of sows in the two treatments; however this comparison was confounded by sows in the DM Area treatment having a lower number of matings per oestrus than those in the other treatment. Observations on the sexual behaviour of pigs at 145 matings indicated that the boars in the DM Area treatment displayed a higher (P<0.05) number of bouts of courting behaviour directed towards the female than boars in the conventional treatment (8.3 and 6.4, respectively). These very limited observations on sexual behaviour suggest that changes in the courting behaviour of bears may be associated with changes in litter size. While there was some indication from the results of progesterone analysis of blood samples taken from unmated gilts that there may have been some differences between treatments in the sexual age of gilts at matings, these differences are unlikely to explain the differences in litter size between treatments. Further research is required to identify the component (s) of the DM Area treatment that are responsible for the improvement in litter size in gilts and to further examine the effects of the two treatments on the reproductive performance of sows.     

Multiple mating reduces male survivorship but not ejaculate size in the polygamous insect Stenomacra marginella (Heteroptera: Largidae)

In polygamous species, successful males should be able to inseminate multiple females, to defeat sperm from previous males, to avoid sperm displacement by other males, and to induce females to use his sperm during fertilization. Since resources are limited, adaptations to perform any of these functions may conflict with each other (and with other life-history traits) and trade-offs are expected to evolve. We studied if males of the polygamous true bug Stenomacra marginella face a trade-off between multiple mating and survivorship, by comparing the survivorship of virgin and multiply mated males. We also looked for physiological costs of ejaculate production by examining ejaculate production in consecutive matings in multiple mated males. Multiply mated males were able to produce ejaculates of similar size in up to six consecutive copulations but they had decreased survivorship in comparison with virgin males. There was no difference in survivorship between males mated three and six consecutive times, suggesting that the negative relation between survivorship and number of copulations is not linear. The decrease in survivorship seems to be a cost of mating and ejaculate production. This cost could favor the evolution of prudence in the allocation of resources to ejaculate production (e.g., cryptic male choice).     

Preliminary observations on sexual behavior and the mating system in free-ranging lesser galagos. (Galago moholi)

Sexual and associated patterns of behavior of lesser galagos (Galago moholi) were recorded during an 18-month study conducted at the Nylsvley Nature Reserve in South Africa. Animals were trapped and fitted with radio transmitter belts in order to monitor nocturnal activities during twice-yearly mating seasons. Most copulations occurred during the last week in May, while a subsidiary (post-partum) mating season occurred in late September-early October. Females came into estrus sequentially during the May season. Adult males exhibited increase in body weight and testes volume during the mating season, changes which were most pronounced among the larger males (> 226 g). Larger males also had the greatest mating success, initiating 88% of observed copulations. Sixty-seven percent of matings involved more than one male copulating with the same female during her estrus, which lasted 1-3 days. Mounts were prolonged (range 2-53 min, mean 9.0 min) and males copulated repeatedly (2-5 times) with the same partner during a single night. These observations of sexual behavior and of large relative testes size in free-ranging lesser galagos are consistent with the occurrence of a dispersed mating system involving sperm competition in this nocturnal prosimian species.     

Effects of multiple mating and male eye span on female reproductive output in the stalk-eyed fly, Cyrtodiopsis dalmanni

Females of the stalk-eyed fly, Cyrtodiopsis dalmanni, mate repeatedly during their lifetime and exhibit mating preferencefor males with large eye span. How these mating decisions affectfemale fitness is not fully understood. In this study, we examinedthe effects of multiple mating and male eye span on short-termreproductive output in this species. Experiments that manipulatedthe number of copulations and partners a female received suggested that obtaining a sufficient sperm supply is an important benefitassociated with multiple mating. The average percentage offertile eggs laid by females increased as a function of matingfrequency and ranged from 40% for females mated once, to 80%for females mated continuously. In addition, a high proportionof copulations in this species appeared to be unsuccessful. One-third of all females mated once laid less than 10% fertileeggs. There was no significant difference in reproductive performancebetween females mated to multiple partners and females matedto a single partner. There was also no indication that femalesreceived any short-term reproductive benefits from mating withmales with large eye span. In fact, females mated to males with short eye span laid a higher percentage of fertile eggs thanfemales mated to large eye span males.     

A note on the scent-marking behavior of two captive-reared feral boars

Male swine are known to scent-mark, but the relationship of this behavior to social rank is unknown and quantitative data for other aspects of the behavior are lacking. A known dominant-subordinate pair of captive-reared feral boars was tested to determine latent periods and frequencies of each type of scent marking exhibited after being stimulated by exposure to feral sows. The boars exhibited metacarpal and preputial scent marking, but not tusk-gland marking. When paired, the dominant boar scent-marked significantly more often than the subordinate, with no significant differences in latent periods. When tested alone, the dominant boar did not mark at all. The subordinate boar did scent-mark when isolated, and frequencies and latent periods did not difder significantly from when paired with the dominant animal. These results suggest that scent-marking behavior varies according to dominance rank and may be influenced by the immediate social environment of the animal.     

The role of temperature on clustering behavior and mating opportunity in Bonin flying foxes

Social thermoregulation is an important adaptation for animals living in cold environments, especially for those with high surface area-to-volume ratios. Huddling behavior can influence animal dispersion patterns. However, little attention has been paid to the relationship between huddling behavior and social organization, including mating systems. We studied aggregations of Bonin flying foxes Pteropus pselaphon on Chichijima Island in Japan, which is located at one of the northern limits of their geographical range. Bonin flying foxes aggregate in arboreal roosts, where they form temporary clusters within the colony during winter months. Specifically, we hypothesized that the occurrence and intensity of clustering behavior are affected by ambient temperature; therefore, we examined the relationship between cluster size and ambient temperature. We also investigated the age and sex compositions of clusters and mating behavior to gain insight into the mating system of this species. Field observations showed that P. pselaphon clusters were roughly separated into three groups: males, females, and subadults. Statistical analyses showed that ambient temperature had significant negative effects on the proportion of individuals that formed clusters for all groups. Cluster size decreased significantly with increasing ambient temperature in female and subadult groups. Some female clusters were composed of a single male and multiple females. Marked males were observed excluding other males from the periphery of female clusters, and they monopolized copulations with clustering females. Our findings suggest that clustering plays an important warming role in the species, and that this behavior is exploited by males resulting in a social system that is best described as a form of female-defense polygyny.