The effects of chronic environmental stress on parturition and on oxytocin and vasopressin secretion in the pig

Previous work has suggested that an acute behavioural confinement in mid-partum can inhibit oxytocin secretion and prolong delivery in the pig, an effect that is opioid mediated. The present experiment investigated the effect of longer-term (chronic) behavioural confinement, that has previously been shown to elevate total plasma cortisol, on speed of delivery and on plasma oxytocin and lysine vasopressin concentrations during the peri-parturient period in primiparous pigs (gilts). Five days before their expected parturition (farrowing) date, gilts with preplaced jugular catheters were either confined to farrowing crates that severely restricted maternal behaviour, or housed in pens that permitted free movement and maternal behaviour (e.g. nest building). Blood samples were taken continuously from 24 h before the birth of the first piglet (BFP) to 6 h post-BFP, and for oxytocin on Days 1, 2, and 7 following parturition (Days P1, P2, P7). Both oxytocin and vasopressin were strongly influenced by parturition (P<0.001). There was no overall effect of chronic crating on either hormone, but crated and penned gilts did show significant differences with respect to the pattern of both oxytocin and vasopressin concentrations over time (P<0.05 in both cases). Oxytocin and vasopressin first increased in crated and penned gilts from 3 h pre-BFP (P<0.05). Crated gilts subsequently showed greater increases in both oxytocin and vasopressin over the first hour of delivery than penned gilts (mean oxytocin (pmol 1⁻¹): 53.3±8.5 vs. 39.7±5.0 for crated vs. penned gilts; mean vasopressin (pmol l⁻¹):4.4±0.7 vs. 2.0±04 for crated vs. penned gilts; both P<0.05). For oxytocin, crated gilts then showed subsequent declining concentrations relative to penned gilts (P<0.05). For vasopressin, penned gilts reached similar concentrations as crated gilts in the third hour post-BFP before vasopressin concentrations in both groups declined. Crated gilts also gave birth to piglets faster in the early stages of delivery (e.g. mean interval between Piglets 2 and 3 (min): 9.6±2.5 vs. 25.6±8.54 for crated and penned gilts, respectively: P<0.02). We conclude that confinement of gilts to a farrowing crate for 5 days neither adversely affects the progress of delivery in the primiparous pig nor the secretion of posterior pituitary hormones involved in parturition.     

Observations on the maternal behaviour of free-ranging domestic pigs

The maternal behaviour of four gilts and one sow having her second litter was studied in two enclosures, measuring 7 and 13 ha. The females left the flocks approximately 24 h before farrowing and moved between 2.5 and 6.5 km during a period of continuous wandering lasting 4–6 h. During this wandering, the pigs seemed to examine and discriminate between different possible farrowing sites. When a site had been chosen, the pigs constructed nests resembling those reported for the European wild boar. After farrowing, the mother and litter remained in or close to the nest for about 9 days. Thereafter, the nests were suddenly abandoned and the piglets changed from hiders to followers. The female and the young joined the flock, but the litter tended to remain an intact social unit throughout lactation and mixed with other piglets only occassionally during resting. No cross-suckling was observed, although some attempts to steal milk from alien mothers were recorded. The piglets were weaned at between 14 and 17 weeks of age. The maternal behaviour was similar to that reported for wild boars and feral pigs. There were individual differences in maternal behaviour among the animals studied, which may be interpreted either as genetically fixed inter-individual differences or as variable strategies, adopted to increase the lifetime reproductive success.     

A retrospective study on the preserving capacity of a commercial boar semen extender

The objective of this study was to evaluate the preserving capacity of a commercial, long-term boar semen extender beyond 4 days in terms of farrowing failure and total born per litter in sows and gilts. Data from 21 farms were subjected to logistic and linear regression analyses to assess the effect of parity (2-5, > 5 and gilts), wean-to-service interval (/= 6 days) and number of AI (1, 2, or 3) on the association between semen age (/=10 days) and fertility. As the semen age increased, the likelihood of farrowing failure increased and total born per litter decreased in sows and gilts. The effect of semen ageing on farrowing failure was more pronounced in sows than in gilts as in the latter it became significant only after 8 days. The effect of semen ageing on total born per litter was similar in both sows and gilts. A lower parity and wean-to-service interval were associated with a reduction in farrowing failure and increase in total born per litter in sows. Increasing the number of inseminations up to two was beneficial in reducing farrowing failure in sows and gilts. A third insemination increased the likelihood of farrowing failure in sows. The number of total born per litter in sows increased with number of inseminations and the effect was not significant in gilts.     

The effect of parity and environmental restriction on behavioural and physiological responses of pre-parturient pigs

There is increasing evidence that restriction of pre-parturient behaviour in pigs is stress-inducing, characterised by an elevation in hypothalamic-pituitary-adrenal (HPA) activity in gilts. To determine whether pigs adapt to behavioural restriction, through modification of nest-building behaviour, we studied pre-parturient pigs in either farrowing crates (no bedding, n=7) or straw-bedded pens (n=7) in their first (gilts) and second (sows) parity, with physiological measurements being taken in the second parity. Observations and blood sampling were carried out during the pre-parturient phase. Crated pigs changed posture more often than penned pigs (F(1,12)=7.06, P<0.05), with the number of posture changes reducing across parities in both environments. The reduction in posture changing was more apparent in the crated sows which may indicate that attempted nest-building behaviour of sows with prior experience of farrowing crates is less fragmented. The crated pigs spent a greater proportion of time sitting across both parities (F(1,12)=9.4, P<0.01), and spent less time manipulating available substrates (F(1,12)=10.67, P<0.05). There was a tendency for penned pigs to spend a greater proportion of time standing (F(1,12)=3.77, P=0.076) with peak nesting behaviour occurring earlier in relation to parturition than in crated pigs. In addition penned sows performed more floor-directed behaviour than penned gilts, and at an earlier stage in relation to parturition. However, crated sows also performed peak nest-building earlier than crated gilts. Plasma cortisol profiles indicated elevated HPA activity in crated sows during the pre-parturient period (F(42,303)=1.43, P<0.05) suggesting increased physiological stress, however, the difference between crated and penned sows was less than that previously seen in gilts. The increased range of pre-parturient behaviours seen in the penned sows suggests that experience may result in an 'improvement' in their nest-building behaviour: earlier preparation of the nest site and then subsequent manipulation of substrates. The crated sows appeared to show some behavioural adaptation to the crate environment; earlier peak in floor directed behaviour and total substrate directed behaviour, reduced posture changing. In conclusion the nest-building behaviour of pigs is modified over parities with adaptation to the behavioural restrictions imposed by the farrowing crate. However, this adaptation, through prior experience, does not completely reduce the elevation in HPA activity previously reported in pre-parturient crated gilts.     

Piglet- and stockperson-directed sow aggression after farrowing and the relationship with a pre-farrowing,human approach test

The aims of the experiment were to determine the incidence and severity of piglet- and stockperson-directed aggression in two different farrowing systems and to determine whether either could be predicted using behavioural and physiological measures recorded previously during a standard human approach test. Sixty-two gilts, permanently housed in groups of 4–5, were approach tested at 6–8 weeks prior to parturition. Gilts were moved to a handling area, fitted with a heart rate monitor and moved to a square test arena. After 2 min familiarisation, an unfamiliar human entered the pen and stood for 3 min against one wall. Then, the human approached the gilt and touched her snout. Behaviour and heart rate were recorded continuously. Social rank was determined for each gilt using pair-wise food competition tests. At farrowing, gilts were randomly assigned to either open pens or conventional crates. At parturition, litter size and piglet weights were recorded and causes of any deaths ascertained, with emphasis on those piglets dying due to savaging. The aggression directed at the stockperson during piglet weighing at birth, 7 days and 14 days of age was scored on a scale of 1–5 (non-aggressive to extremely aggressive). Five gilts savaged their piglets and five other gilts were particularly aggressive towards the stockperson. Savaging of piglets and levels of stockperson-directed aggression were higher in the open pen system than in farrowing crates. Gilts that savaged piglets were more likely to show ‘shy’ behaviour during the human approach test, whereas gilts that were highly aggressive towards the stockperson were more likely to show ‘bold’ behaviour in the same test. Stockperson-directed aggression was displayed consistently, both within the same lactation and between subsequent lactations. Stockperson-directed aggression was unrelated to piglet survival but did confer advantages in piglet growth rate between birth and 7 days of age.     

Evidence of a limited role for prolactin in the preparturient activity of confined gilts

To investigate the role of peripheral prolactin in stimulating the preparturient activity of pigs, 12 cross-bred gilts housed in standard farrowing crates either received orally 10mg of bromocriptine three times per day from day 110 of gestation or served as controls. Jugular blood samples were collected on days 107 and 113 and assayed for prolactin, while the gilts' behaviour was recorded during the last 24h before parturition. Bromocriptine eliminated the preparturient rise in prolactin concentrations (P=0.002). As parturition approached all gilts initially spent less time laying down and more time standing or sitting. The frequency of posture changes also increased as did the incidence of oro-nasal behaviours. These trends were reversed during the final 5-8h before parturition, when the gilts began to lay down for longer periods. The mean concentrations of prolactin on day 113 were correlated with the frequency of posture changes (r=0.70,P=0.015) but not with any other behavioural measure (P>0.10). Bromocriptine had no overall effect on any of the preparturient behaviours (P>0.10) but did reduce the frequency of posture changes 13-16h before parturition (P=0.05). There was a significant interaction between time until parturition and bromocriptine treatment for time spent lying down (P=0.013): bromocriptine delayed the time when the gilts began lying down again as parturition approached. The results suggest that peripheral prolactin plays only a limited role in the preparturient activity of pigs and throws some doubt on its importance in the motivation of nest building in this species.     

The effects of branches on prepartum nest building in gilts with access to straw

Sows farrowing in a semi-natural environment terminate nest building 1-7 h prior to parturition after having built a nest for which a variety of materials are used. No nest-building behaviour occurs during parturition and the sows remain lying in the nest throughout most of the farrowing. In contrast, many intensively housed sows are restless during farrowing. To investigate whether gilts housed indoors would use branches for nest building and whether access to branches would affect the termination of nest building and parturient behaviour, we studied gilts housed individually in pens designed to stimulate natural nest building. The control group (n=21) had unlimited access to straw and the experimental group (n=21) had unlimited access to straw and branches. During nest building all the gilts used straw and all the experimental gilts also used branches. In the experimental group the interval from termination of nest building to birth of the first piglet (BFP) was significantly longer than in the control group (132 versus 58 min, P=0.04). In the experimental group, nest-building behaviour was also performed by fewer individuals during the interval from BFP until 2 h after than in the control group (38% versus 71% of the gilts, P=0.03). Gilts that performed nest building during this interval carried out more postural changes (P<0.001) and spent less time in lateral recumbency (P=0.001) than gilts which did not perform nest building. On average, gilts that performed nest building behaviour after BFP (n=26) spent 54% of the first 2 h of parturition in lateral recumbency and carried out 16 postural changes. Gilts that did not perform nest building behaviour during this interval (n=16) spent 85% of the time in lateral recumbency and carried out five postural changes. In 10 gilts that were selected randomly from the experimental group nest building was studied in more detail. In these gilts nest building peaked between 17 and 6 h prepartum. There was no difference in amount of behaviour directed towards straw and amount of behaviour directed towards branches.The results indicate that the termination of nest building in sows is under environmental feedback control. When only straw was provided the nests did not have much of a lasting structure. However, when gilts had access to straw and branches more structured and functional nests could be built. These nests may have been more effective in reducing the motivation for nest building prior to the onset of parturition.     

Relationship between pre-partum relaxin concentrations and farrowing intervals in the pig

Gilts were treated on Day 112 of gestation with saline or a prostaglandin (PG) F-2 alpha analogue. In control gilts there was a rise in the relaxin concentration from 48 h before the onset of delivery, peaking between 12 and 28 h pre partum followed by a steep fall. The relaxin concentrations at each 1-h time interval were analysed in relation to the farrowing interval for each gilt using correlation analysis. There was a significant (at least P less than 0.05) positive correlation between the relaxin concentration and the farrowing interval at every time period from 14 to 2 h before delivery. In contrast there was little relationship between concentrations of progesterone, oestrone and oestradiol-17 beta and farrowing intervals. The gilts treated with PGF-2 alpha analogues had steroid profiles indistinguishable from those in controls but differing relaxin secretion patterns. Relaxin concentrations peaked at 1-2 h after PGF-2 alpha injection and this was followed by a second smaller increase closer to the time of delivery in 7 out of 12 gilts. The 'two-peak' gilts had significantly higher relaxin concentrations at farrowing and took significantly longer to farrow than did the 'one-peak' gilts (P less than 0.005). These results suggest that high relaxin concentrations during the last 14 h before the onset of parturition are associated with increased farrowing times, but are not associated with any increase in neonatal mortality.     

The effects of confinement on periparturient behaviour and circulating prolactin,prostaglandin F2α and oxytocin in gilts with access to a variety of nest materials

In a 2×2 factorial experiment, the effects of gestation and farrowing housing on (1) periparturient behaviour and circulating prolactin, prostaglandin F_2α (PGF_2α) and oxytocin in gilts with access to peat, straw and branches, and (2) correlational relationships between the periparturient behaviour and hormones were studied. The treatments consisted of housing in stalls or pens from mating to day 110 of gestation followed by farrowing crates or pens until after parturition. Landrace×Yorkshire gilts were observed from video recordings (n=25) from 20 h prepartum and blood sampled via jugular catheters (n=16) from 24 h prepartum until 2 h after the birth of the first piglet.There was an interaction between gestation and farrowing housing affecting the start of nest-building (P=0.03). Gilts that experienced a change in type of housing accommodation commenced nest-building closer to parturition than gilts that were penned both during gestation and at farrowing (both P<0.05). There were no effects of the housing environment on the timing of termination of nest-building, behaviour during parturition, or the course of parturition. However, relative to base level, crated gilts sat more from 16 to 6 h prepartum, whereas this was the case for penned gilts only from 9 to 7 h prepartum. Crated gilts also tended to change posture more often (P=0.07) and lie more in sternal recumbency (P=0.095). This suggests that familiarity with the environment in combination with space to move about and/or availability of materials is important in the timing of nest-building. Confinement during farrowing did not appear to impair feed-back from the materials and the nest, although increased number of postural changes may reflect the motivation but inability to nest-build, or general discomfort in the crate.There was a development over time in postural and nest-building behaviours as well as in plasma concentrations of prolactin, PGF_2α (measured by the metabolite PGFM) and oxytocin, but there were only few effects of housing treatments on hormones or associations between behaviour and hormones. The results suggest that nest-building occurs independently of a prepartum rise in prolactin, but that oxytocin may be associated with the termination of nest-building as there was a negative correlational relationship with nosing (P<0.01) and arranging nest-building materials (P<0.001).Farrowing crate housing appeared to have fewer effects on periparturient behaviour and course of parturition than reported in previous studies where effects of confinement and provision of nest-building materials may have been confounded. Thus, provision of nest-building materials to crated sows may have beneficial effects on sow behaviour and welfare.     

Strategies alimentaires et statut social chez le sanglier en captivite

We have studied feeding and social behaviours in 7 captive wild boars before and after farrowing and their early development.The individual feeding strategies are varying between two types : “Feeding at the feeders” and “Rooting”. Most of the individuals (5) are changing their feeding strategy in the second period, after farrowing. The social interactions in the group are also changed after farrowing ; thus in the second period, females with youngs reduced their agonistic interactions, established affiliated relationships and keep away from the rest of the group. The frequency of approach of the feeders is positively correlated to the degree of affinity and not to the dominance hierarchy. Furthermore, the correlation between the feeding strategy and the individual social status is positive only before farrowing : the social capacity of affiliated behaviour units and the polarity of agonistic interactions is linked to the strategy “Feeding at the feeders”.From the third week of age, different individual feeding and social behaviours are appearing : the youngs develop the same types of strategy as their genetic or adoptive mother. Then it appears a relation between the social status of the mothers and the feeding strategies of the youngs.     

Peri-partum posture and behaviour of gilts and the location of their piglets in lines selected for components of efficient lean growth

Peri-partum posture and behaviour of gilts from lines selected for different components of efficient lean growth were studied to determine if behavioural changes may have been associated with the observed responses in reproductive performance. The proportions of time that gilts expressed defined posture and behaviour traits and the locations of their piglets were determined from video recordings of observations made at 5min intervals in the period extending from 2h pre-farrowing to 2h post-farrowing. The 137 gilts studied were from four pairs of Large White lines which had been divergently (high and low) selected for either daily food intake (DFI), lean food conversion efficiency (LFC), lean growth rate on ad libitum feeding (LGA) or lean growth rate on a restricted feeding scale (LGS).Almost all the significant (P<05) changes occurred in the LGS pair of lines. In the pre-farrowing period, relative to the low LGS gilts, high LGS gilts spent a higher proportion of their time lying on their sides (0.92 versus 0.69), and less time in the upright postures of standing, sitting or lying on their bellies (0.08 versus 0.33) and engaging in nesting behaviour (0.02 versus 0.10). During farrowing, high LGS gilts again lay on their sides more often than low LGS gilts (0.96 versus 0.80) and were upright less often (0.04 versus 0.20). High LGS gilts changed posture less often than low LGS gilts (0.05 versus 0.31) but were more often alert (0.79 versus 0.61). During farrowing, high LGS piglets were seen less often at their mother's head, back and vulva or at the creep than low LGS piglets (0.06 versus 0.15). Post-farrowing, there were no significant differences between the lines, almost all gilts lying on their sides with their piglets at the udder. Divergent selection for components of efficient lean growth rate on ad libitum feeding was not associated with consistent responses in gilt posture and behaviour or in piglet location. Selection for high lean growth on restricted feeding had effects on gilt posture and behaviour which may have been beneficial to her welfare and that of her piglets.     

Reproductive performance of gilts and sows in temperate versus subarctic and arctic zones of Norway

The reproductive performance of gilts and sows from two regions in Norway was investigated in a retrospective analysis of data from the litter recording system. In the Northern region (North; between 65°N and 71°N), there are extreme shifts in natural photoperiod between winter and summer. In the Southern region (South; between 59°N and 60°30′N), photoperiodic changes are less dramatic.

Gilts were 8 days older at first mating or insemination in the North than in the South (P<0.01). A significantly lower proportion of sows in the North were mated or inseminated within 5 days post-weaning than in the South, a difference present both among primiparous and multiparous sows (P<0.01). Overall farrowing rate in the North was lower than in the South, but litter size (total number born) among those pigs that farrowed was larger. After correction for year, month, breed and age at first service, there were still lower odds of farrowing for gilts in North than in South. Neither for primiparous nor multiparous sows were regional differences in farrowing probability significant when year, month, breed and weaning to service interval were included in the model. Gilts and primiparous sows had a lower probability of farrowing following insemination during summer or autumn months, but service month was not significantly related to the farrowing probability of multiparous sows.

For gilts, litter size was positively related to age at first service. For sows, litter size was lowest at weaning to service intervals between 6 and 10 days. Total numbers of piglets born per litter were estimated to be 0.36, 0.38 and 0.55 larger in the North than in the South (differences in least square means; gilts, primiparous sows and multiparous sows, respectively) (P<0.01). Litter size was lower after service during natural long photoperiod than during the rest of the year.     

Effect of insemination of estrus-induced prepuberal gilts on ensuing reproductive performance and body weight

Prepuberal gilts reared and managed to 85-90 kg live weight in a common system were allocated at random to one of three first-mating treatments in an experiment conducted over a period of more than 5 years. In two of the treatments, gilts received a single i.m. injection of 400 IU equine chorionic gonadotropin (eCG) and 200 IU human chorionic gonadotropin (hCG) (PG600; Intervet) and were either inseminated 4 and 5 days later on a fixed-time basis regardless of oestrus (treatment A), or at the second oestrus following treatment (treatment B). The third group of gilts remained untreated and was inseminated on the first spontaneous oestrus (treatment C). Thereafter, all gilts were managed in the same way and those observed in oestrus were re-inseminated. Significantly more gilts returned to oestrus after the first service in treatment A (35%) than in treatment B and C (12 and 17%, respectively; P<0.01). Gilts farrowed to the first or repeat inseminations at a significantly younger age (P<0.01) in treatment A (304 days) than treatment B (324 days) and C (320 days). The age difference at farrowing remained in surviving gilts at the end of their third parity. The first farrowing performance of the gilts was significantly affected by treatment in terms of litter size at birth (A 7.0, B 8.4 and C 8.3 live piglets per gilt; P<0.01), litter size at weaning (A 6.2, B 7.2 and C 7.2 live piglets per gilt, P<0.05), and piglet birth weight (A 1.4, B 1.3 and C 1.3 kg; P<0.05) but piglet survival rate and weaning weight were not affected by treatment. The live weights of the gilts were significantly different between the treatments at first insemination (A 95.7, B 106.5 and C 109.2 kg; P<0.01) but not when the first litter was weaned (A 133.6, B 135.1 and C 136.6; P>0.05). After the first farrowing there were no differences between the treatments in terms of the survival rate, productive or reproductive performance of the gilts/sows and their offspring. Without conducting a detailed cost-benefit-calculation it was deduced that, from an economical point of view, differences between treatment A and treatments B and C are negligible because the savings associated with farrowing at a younger age on this treatment just about compensated for any additional costs associated with the treatment and the lower number of piglets born at the first farrowing.     

Influence of time of insemination relative to ovulation and frequency of insemination on gilt fertility

The objectives of this study were to determine the optimal time of insemination in the pre-ovulatory period (from 32 to 0 h before ovulation) and to evaluate once-daily versus twice-daily inseminations in gilts. In Experiment 1, pre-puberal gilts (n=102) were observed for estrus every 8h and ultrasonography was performed every 8h from the onset of estrus to confirmation of ovulation. The gilts were inseminated once with 4 x 10(9) spermatozoa at various intervals prior to ovulation. Pregnancy detection was conducted 24 days after AI and gilts were slaughtered 4-6 days later. Corpora lutea and the number of viable embryos were counted and the embryo recovery rate was calculated (based on the percentage of corpora lutea). Inseminations performed <24h before ovulation resulted in a higher embryo recovery rate (P=0.02) and produced 2.1 more embryos (P=0.01) than inseminations >or=24h before ovulation. However, the pregnancy rate was reduced when inseminations were performed >16 h before ovulation (P=0.08). In Experiment 2, pre-puberal gilts (n=105) were observed for estrus every 12h and ultrasonography was performed every 12h from the onset of estrus to confirmation of ovulation. Gilts were inseminated (with 4 x 10(9) spermatozoa) 12h after the onset of estrus, with inseminations repeated either every 12h (twice-daily) or 24h (once-daily) during estrus. The gilts were allowed to farrow. There were no differences (between gilts bred twice-daily versus once-daily) for return to estrus rate (P=0.36) and adjusted farrowing rate (P=0.19). However, gilts inseminated once-daily had 1.2 piglets less than those inseminated twice-daily (P=0.09). In conclusion, gilts should be inseminated up to 16 h before ovulation, as intervals >16 h reduced pregnancy rate and litter size.     

The experimental model of establishment and maintenance of social hierarchy in laboratory mice

The goal of the investigation is to establish a new experimental model of social hierarchy in laboratory mice. The important feature of the model is a group of two males only placed into the special experimental cage. The cage consists of two nestling chambers and central chamber. Observations were made 3 times per day (20 min each) throughout 5 days. Aggression, defence and sniffing behaviours of both partners were recorded during each observation period using video camera. Social rank was detected by asymmetry in aggressive behaviour. It was shown that social hierarchy was established during the first four tests limited by the first 24 h after pairing. After this period aggression and defence behaviours were greatly decreased. After the first 5 tests a stabilization in aggression (number of wins, active attacks and not direct aggression) and defence (number of vertical defensive postures and escapes) as well as sniffing behaviours took place. But a strong asymmetry in mentioned here behaviours in males of different ranks (dominants and subordinates) was kept up. Thus we offer a new experimental model of minimal society, which entirely reproduces a pattern of establishment and maintenance of social hierarchy. Our model demonstrates significant differences in agonistic, defence and sniffing behaviours between males of different social rank.     

Prepartum plasma estradiol and postpartum cortisol, but not oxytocin, are associated with interindividual and breed differences in the expression of maternal behaviour in sheep

Consistent, individual differences in the expression of maternal behaviour have been described in several species including the sheep. The neuroendocrine mechanisms underlying the onset of maternal behaviour in the sheep have been described, although the relationship between hormonal events and individual differences in behaviour has yet to be determined. In this study, we examined whether the individual differences in plasma estradiol, progesterone, oxytocin and cortisol concentrations were related to observed individual and breed differences in maternal behaviours in two breeds of sheep (Scottish Blackface and Suffolk) known to differ in maternal behavioural expression. Maternal estradiol concentration increased rapidly before parturition and was higher in Blackface ewes than Suffolk ewes. Plasma progesterone declined before parturition and was higher in Suffolk than Blackface ewes. Prepartum estradiol, but not progesterone, was related to individual differences in maternal grooming of the lamb. Plasma oxytocin did not differ between breeds in late gestation. There was a tendency for oxytocin to be higher in Blackface than Suffolk ewes immediately after birth. However, there were no significant relationships between prepartum or postpartum oxytocin and any maternal behaviours. Plasma cortisol was higher in Blackface than Suffolk ewes in the last days of pregnancy but rose in both breeds over the last 24 h before parturition and did not differ at delivery. Cortisol peripartum was negatively related to individual differences in maternal affiliative behaviours. These data suggest that estradiol, and potentially cortisol, may mediate individual differences in maternal behaviour in sheep.     

Exogenous prostaglandin F(2)alpha at time of ovulation improves reproductive efficiency in repeat breeder sows

In order to determine if PGF(2)alpha could improve fertility in repeat breeder females when added to semen used for artificial insemination (AI) the following trial was performed. In a large indoor Hungarian production unit of 2000 sows, 667 repeat breeding females were assigned to two groups and were treated as follows: Group 1 (n=322), received PGF(2)alpha, added to the semen immediately before AI; Group 2 (n=345), received AI with untreated semen. Conception rate, farrowing rate, subsequent total and live born litter size and subsequent weaning to estrus intervals were evaluated. Conception and farrowing rates revealed highly significant differences between the PGF(2)alpha-treated and nontreated animals (P<0.001). Subsequent total born (P<0.07), and live born litter size (P<0.13), and subsequent weaning to estrus intervals (P<0.23) showed no significant differences. It is reasonable to suggest that exogenous PGF(2)alpha added to AI semen improves conception and farrowing rates.     

Confinement of sows for different periods during lactation: effects on behaviour and lesions of sows and performance of piglets

Alternatives to farrowing crates with continuous confinement of the sow are urgently needed because the animal welfare is negatively impacted. Given the increase of herd sizes, practical experience with loose-housing is needed to force the implementation of these systems in the field. Next to aspects of labour efficiency, detrimental piglet mortality rates that may occur during the first days postpartum (pp) is a major criticism. Therefore, loose-housing after a crating period limited to the first days pp might be a feasible alternative to improve welfare under intensive production conditions. The aim was to investigate the effect of crating sows during lactation for different periods on their behaviour and integument alterations and on piglets’ performance. Gilts from a commercial herd were observed from 5 to 26 days pp and housed in farrowing crates (1.85×2.50 m) that could be altered between confinement crates and loose-housing pens. Animals were divided into three groups, that were either crated continuously from birth until weaning (Group A, n=55), until 14 days pp (Group B; n=54) or 7 days pp (Group C, n=59). The behaviour of six randomly selected gilts per group was video recorded from 5 to 26 days pp and analysed by time sampling technique. Lesions on the legs, shoulder and lumbar vertebra were scored on days 7, 14 and 25 pp. Piglets were weighed weekly, causes of losses recorded and weight losses of gilts measured. Not different between groups (P>0.05), animals spent 72 to 76% lying laterally, 14 to 17% lying in abdominal or semi-abdominal position, 9 to 10% standing and 1 to 3% sitting. B-sows were lying longer in week 3 and 4 of lactation compared to A- and C-sows (P<0.05). The incidence of slight shoulder lesions rose from <1% on day 7 to 4% on day 14 and 14% on day 25 pp. On day 25 pp, 5% of all studied gilts showed moderate shoulder lesions. Piglet mortality rates were 11.4%, 12.9% and 13.3% for groups A, B and C, respectively (P>0.05), whereas almost 90% of the losses occurred in the first week pp. In conclusion, loose-housing of lactating gilts after a reduced postnatal crating period of 7 days affected neither the activity level of the gilts and lesions on the integument nor pre-weaning mortality. Therefore, it is recommended to allow sows to move around to some extent during the later lactation period.     

Effectiveness of frozen boar semen under practical conditions of artificial insemination

A technique of boar semen deep-freezing and frozen semen use was tested in practice. 338 sows and 43 gilts belonging to small herds with less than 10 females each were inseminated without oestrus detection by a teaser boar. About 58 % of the inseminated females produced 9.3 piglets per litter. But there were differences between parities. The sows had the highest fertility rate, whereas the gilts showed a significantly lower farrowing rate (59.8% vs 41.9%; P < 0.05). The standing reaction of the female to the back pressure test made by the inseminator and the behaviour of the female during insemination had an effect on the farrowing rate. The best result was obtained after a standing reaction and a behaviour score of 1 (64.5% and 9.6 piglets for farrowing rate and litters size respectively). Farrowing rate for inseminators ranged from 44.3% to 62.4% among inseminators. Farrowing rate for females inseminated with frozen semen from Large-White, Landrace, Pietrain boars was not different, but there were significant differences between the boars. Results showed that insemination with deep-frozen boar semen could be used under practical conditions as an additional technique to the use of fresh semen.     

Differences in follicular morphology, steroidogenesis and oocyte maturation in naturally cyclic and PMSG/hCG-treated prepubertal gilts

Ovaries were obtained from naturally cyclic pigs on Days 16-17, 18, 19, 20 and 21 of the oestrous cycle and on the basis of observed follicular characteristics were assigned as representative of the early (Group 1), mid- (Groups 2 and 3) or late (after LH; Group 4) follicular phase. Follicular development in cyclic gilts was compared with that in ovaries obtained from late prepubertal gilts 36 (Group 5) or 72 (Group 6) h after treatment with 750 i.u. PMSG alone, or with a combination of 500 i.u. hCG 72 h after PMSG and slaughter 30-40 h later (Group 7). After dissection of all follicles greater than 2 mm diameter, follicular diameter, follicular fluid volume, follicular fluid concentrations of progesterone, oestradiol and testosterone, and the stage of oocyte maturation were determined. Combined PMSG/hCG treatment of immature gilts resulted in a pattern of follicular development different from that in naturally cyclic gilts during the follicular phase. Overall exogenous gonadotrophin treatment also increased (P less than 0.001) the variability in follicular diameter and fluid volume. Comparisons between appropriate groups also established differences in the variability of both morphological (diameter and volume, Group 1 vs Group 5; P less than 0.05) and biochemical development (follicular fluid oestradiol, Group 3 vs Group 6 and Group 4 vs Group 7; both P less than 0.05). Such differences in both morphological and biochemical characteristics between cyclic and PMSG/hCG-treated gilts were particularly evident in the population of larger (greater than 6 mm) follicles. These results indicate that the pattern of follicular development in naturally cyclic and in PMSG/hCG-treated gilts is dissimilar and suggests that the ovaries of gonadotrophin-treated prepubertal gilts are functionally different from the ovaries of mature females.