Parturition control in sows with a prostaglandin analogue (alfaprostol)

The objective of this study was to determine the dose of alfaprostol (18, 19, 20-trinor-17-cyclohexyl-13, 14 didehydro-PGF(2)alpha-methylester) and the day of administration most effective in inducing sows to farrow during normal working hours (0700 to 1700). One-hundred forty multiparous crossbred sows, taken from a herd whose mean gestation length was 114.3 days, were assigned to one of five treatment groups: 1) control vehicle-propylene glycol, 2) 0.5 mg alfaprostol (AP). 3) 1 mg AP, 4) 2 mg AP and 5) 3 mg AP. Sows received an intramuscular injection of AP between 0800 and 0830 on either day 111, 112 or 113 of gestation. Parameters studied included interval from injection to birth of first pig, farrowing interval, total number of pigs born, number born alive, average birth weight, percent stillborn, interval from weaning to next estrus and number born alive next litter. The mean intervals from injection to the birth of the first pig were 55.2 +/- 7.1; 41.1 +/- 5.1; 29.6 +/- 4.0; 24.3 +/- 1.1; 24.8 +/- 0.9 h for groups 1, 2, 3, 4 and 5, respectively (P<0.05). The percentage of sows that farrowed during normal working hours (23 to 33 h after injection) for groups 1, 2, 3, 4 and 5 were 15, 53, 60, 77 and 70%, respectively. Average birth weights (kg) for treatment groups 1, 2, 3, 4 and 5 were 1.54 +/- 0.05; 1.65 +/- 0.05; 1.59 +/- 0.05; 1.54 +/- 0.05 and 1.42 +/- 0.05, respectively (P<0.05). Mean differences in total number of pigs born and number born alive were also statistically significant (P<0.05) but stillbirth rate was not different (P>0.05) among treatment groups. These results indicate that a single injection of 1, 2 or 3 mg of alfaprostol will successfully induce parturition the following day in a majority of the treated sows.     

Induction of parturition in the sow with prostaglandin F2α

Sows were injected with prostaglandin F₂α to induce parturition. Blood was collected to determine the effect of PGF₂α on plasma progesterone and estrogen levels. Parturition occurred significantly earlier (P<.01) in the 14 treated animals than in the 9 untreated animals. Nine out of fourteen treated sows farrowed within 48 h after treatment. Whereas untreated sows farrowed 11.6 ± 6.7 h after the predicted time of parturition, treated sows farrowed 48 ± 8.8 h before the predicted time. PGF₂α was most effective in those sows in which plasma progesterone decreased quickly. Plasma estrogen levels remained reasonably constant after treatment.     

Effect of oral progesterone and caffeine at the end of gestation on farrowing duration and piglet growth and survival

The profitability of pig production is constrained by high incidences of peri-parturient and pre-weaning piglet mortality. Supplementing sows with either progesterone or caffeine during the last week of gestation can reduce stillbirths and improve piglet performance. However, the consequences of combining these two substances has not been investigated. The aim of the current study was to determine the effect of oral supplementation of sows with progesterone (regumate) and caffeine at the end of gestation on the timing and progression of farrowing, as well as piglet survival and growth to weaning. From days 111 to 113 of gestation, 20 Large White pregnant sows (parity 3.0±0.45) received 5 ml of Regumate Porcine (0.4 w/v oral solution; MSD Animal Health) daily on top of their morning ration. Sows were stratified according to parity and predicted farrowing date, and allocated at random to receive a diet supplemented with either 0 g caffeine/kg diet (CONT) or 2.4 g of caffeine/kg diet (CAFF) from day 113 of gestation until parturition (n=10 sows/treatment). Treatment did not affect total litter size; however, CONT sows gave birth to more live and fewer dead piglets compared with CAFF sows; 14.5±0.73 v. 11.7±1.03 and 0.7±0.20 v. 3.2±0.77; P<0.05). Mean, minimum and maximum piglet birthweight were unaffected by treatment. Compared with the control, caffeine increased the proportion of piglets with a birthweight <1 kg (0.16±0.05 v. 0.05±0.02; P=0.072) and decreased the proportion of live born piglets surviving to day 5 postpartum (0.77±0.06 v. 0.90±0.02; P<0.05) and to weaning (0.74±0.06 v. 0.90±0.02; P<0.05). Overall, the current data provided the first evidence that caffeine supplementation of sows receiving progesterone to prevent premature farrowing impaired piglet survival during, and shortly after parturition. This negative outcome may be linked to extended farrowing durations and an increase in the proportion of very light piglets at birth. These data provide compelling, albeit preliminary, evidence that caffeine and progesterone should not be used together at the end of gestation.     

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.     

Induction of parturition in swine with prostaglandin F(2)alpha, estradiol benzoate and oxytocin

Pregnant sows and gilts were administered either 0, 2.5, 5, 10 or 20 mg prostaglandin F(2)alpha (PGF(2)alpha) intramuscularly on Day 112 or 113 of gestation at 0800 h in an effort to induce parturition. The average interval from PGF(2)alpha injection to farrowing was 55.1 +/- 5.7, 29.4 +/- 3.1, 32.1 +/- 4.6, 27.8 +/- 1.8 and 26.9 +/- 1.1 h for 0, 2.5, 5, 10 and 20 mg, respectively. All PGF(2)alpha treatments increased (P < 0.01) over controls the number of sows farrowing 23 to 33 h after injection. The average gestation length was significantly shorter in treated gilts; however, no detrimental effect on pig performance or pig survivability was observed. A second trial evaluated the effect of a 10-mg dose of PGF(2)alpha on the induction of parturition in sows in order to obtain a majority of sows farrowing within normal working hours (0700 to 1700 h). The interval from injection to farrowing was decreased (P < 0.05) by PGF(2)alpha treatment (66.2 +/- 5.3 vs 28.1 +/- 2.2 h). Fifty-seven percent (P < 0.05) of PGF(2)alpha-treated sows farrowed between 0700 and 1700 h as compared to 13.6% for control sows. A third trial was conducted to examine a sequential treatment of PGF(2)alpha and oxytocin to control the time of parturition more precisely. Sows receiving only 10 mg of PGF(2)alpha farrowed on an average 31.1 +/- 1.4 h after injection. The injection of 40 IU oxytocin 24 to 28 h after PGF(2)alpha decreased (P < 0.05) the interval from PGF(2)alpha to farrowing (28.1 +/- 0.9 h). The addition of oxytocin increased (P < 0.05) the number of sows farrowing within 3 h of injection (33 vs 86% for PGF(2)alpha and PGF(2)alpha + oxytocin treatments, respectively). A fourth trial was designed to determine if the addition of exogenous estradiol benzoate (EB) to a sequential treatment of PGF(2)alpha and oxytocin would improve the predictability and synchronization of the induced parturition. Sows were assigned to receive either saline, 10 mg PGF(2)alpha + 40 IU oxytocin or 10 mg PGF(2)alpha + 5 mg EB + 40 IU oxytocin. The addition of EB reduced (P < 0.01) the variance in the interval from oxytocin to farrowing and added precision to the predicted time of induced parturition.     

Variability and repeatability in gestation length related to litter performance in female pigs on commercial farms

Forecasting gestation length (GL) in sows enables producers to be prepared to provide assistance at farrowing, or for timely treatment to induce parturition. The objectives of the present study were to determine GL across parities, the repeatability and correlation of the GL, and associations of GL with the three litter size variables (total pigs born, pigs born alive, and dead piglets) and longevity. This study was conducted on 94 farms and encompassed 66,254 farrowing records of 13,715 sows born during 1999. Variance components and correlation analyses were used to determine the repeatability and the correlations of GL. Mixed-effects models were used to analyze associations of GL with litter size variables and longevity. The mean of GL across parities was from 115.2 to 115.4 d. The proportions of GL 114, 115, and 116 d for all farrowing events were 19.2, 30.8, and 22.2%, respectively. The GL between parities were correlated (0.40/=117 d (P<0.01). Sows with GL相似文献   

The influence of allyl trenbolone (Regumate) on the timing,duration and endocrinology of parturition in sows

A study was undertaken to evaluate the effects of using an oral progestagen for synchronisation of parturition in the sow. Multiparous Landrace X Large White sows were fed 20 mg allyl trenbolone daily from day 110 to 115 of gestation then 15 mg on day 116 (Group R; N = 12); untreated sows of similar background served as controls (Group C; N = 9). Blood samples, taken at 8-h intervals from day 110 of gestation to onset of parturition, then every 4 h until parturition was complete, were assayed for plasma levels of progesterone, unconjugated oestrone, cortisol and prolactin. Duration of farrowing, incidence of stillbirths and individual piglet birth weights were recorded. Five Group R sows farrowed during the period of progestagen administration, while for the remaining 7, the mean interval from last progestagen treatment to emergence of first piglet was 31.6 ±5.5 h. Gestation length, duration of parturition, and mean interval between successive births all were longer in Group R than in Group C (116.5 ± 0.34 compared with 115.0 ± 0.52 days, P < 0.01; 9.73 ± 1.98 compared with 3.08 ± 0.70 h, P < 0.01; and 53.4 ± 10.2 compared with 16.2 ± 2.4 min., P < 0.01, respectively). No significant treatment differences were apparent for litter size at birth, proportion stillborn or piglet birth weights. Profile analysis showed that plasma progesterone levels in Group R were lower (P < 0.05) during the 30 h prefarrowing, suggesting a longer mean interval between functional luteolysis and parturition in these animals. In both Groups plasma levels of unconjugated oestrone rose in the prefarrowing period, the levels being higher (P < 0.05) in Group R Peak oestrone levels occurred at the commencement of, and had declined to low levels by the completion of, farrowing. Cortisol levels exhibited a pattern similar to that of oestrone, although peak levels at parturition were lower in Group R (P < 0.01). Plasma prolactin levels in the 24 h prepartum rose faster and reached higher levels (P < 0.05) in Group C than Group R, but the difference was no longer apparent subsequent to first piglet emergence. It is concluded that the use of this progestagen to delay parturition upset the synchronisation of endocrine events at farrowing, resulting in an increased duration of parturition.     

Effects of tail docking and docking length on neuroanatomical changes in healed tail tips of pigs

In pig production, piglets are tail docked at birth in order to prevent tail biting later in life. In order to examine the effects of tail docking and docking length on the formation of neuromas, we used 65 pigs and the following four treatments: intact tails (n=18); leaving 75% (n=17); leaving 50% (n=19); or leaving 25% (n=11) of the tail length on the pigs. The piglets were docked between day 2 and 4 after birth using a gas-heated apparatus, and were kept under conventional conditions until slaughter at 22 weeks of age, where tails were removed and examined macroscopically and histologically. The tail lengths and diameters differed at slaughter (lengths: 30.6±0.6; 24.9±0.4; 19.8±0.6; 8.7±0.6 cm; P<0.001; tail diameter: 0.5±0.03; 0.8±0.02; 1.0±0.03; 1.4±0.04 cm; P<0.001, respectively). Docking resulted in a higher proportion of tails with neuromas (64 v. 0%; P<0.001), number of neuromas per tail (1.0±0.2 v. 0; P<0.001) and size of neuromas (1023±592 v. 0 μm; P<0.001). The results show that tail docking piglets using hot-iron cautery causes formation of neuromas in the outermost part of the tail tip. The presence of neuromas might lead to altered nociceptive thresholds, which need to be confirmed in future studies.     

Genetic associations between maternal traits and aggressive behaviour in Large White sows

The present study examined the possibilities and consequences of selecting pigs for reduced aggression and desirable maternal behaviour. Data were recorded from 798 purebred Large White gilts, with an age of 217±17.7 (mean±SD) days, which were observed at mixing with unfamiliar conspecifics. The reaction of the sows towards separation from their litter was assessed for 2022 litters from 848 Large White sows. Sows’ performance during their time in the farrowing unit was scored based on the traits farrowing behaviour (i.e. need of birth assistance), rearing performance (i.e. litter quality at day 10 postpartum (pp)), usability (i.e. additional labour input during lactation period e.g. for treatments) and udder quality of the sow (i.e. udder attachment). For agonistic behaviour, traits heritabilities of h²=0.11±0.04 to h²=0.28±0.06 were estimated. For the sow’s reaction towards separation from her litter low heritabilities were found (h²=0.03±0.03 for separation test on day 1 pp and h²=0.02±0.03 for separation test on day 10 pp). Heritabilities for lactating sow’s performance (farrowing behaviour, rearing performance, usability of the sow and udder quality) in the farrowing unit ranged from h²=0.03±0.02 to h²=0.19±0.03. Due to these results it can be assumed that selection for these traits, for example, for udder quality or reduced aggression, is possible. Antagonistic associations were found between separation test on day 1 pp and different measures of aggressiveness (r_g=−0.22±0.26 aggressive attack and r_g=−0.41±0.33 reciprocal fighting). Future studies should determine economic as well as welfare-related values of these traits in order to decide whether selection for these traits will be reasonable.     

Intrauterine insemination of sows with reduced sperm numbers: results of a commercially based field trial

Artificial insemination (AI) in pigs requires 2-3 billion spermatozoa to achieve consistently high fertility with current practice of inseminating into the posterior region of the cervix. We have investigated the potential advantages of inseminating through the cervix into the caudal region of the uterus using lower sperm numbers. Total sperm doses from 22 boars of 3, 2 or 1 billion spermatozoa were packaged in 80 ml volumes in X-Cell extender in gene-flat-pack (Cochette) bags. A novel inseminating device, the Deepgoldenpig, was employed which permits the ready introduction of a narrow catheter through the cervix into the uterus without traumatic injury to the mucosa. This was compared with the standard Goldenpig device that allows semen to be deposited in the posterior folds of the cervix. Sows of two different genotypes and of parities ranging from 2 to 11 were used. They were selected solely on the basis of a weaning to estrus interval of 4-6 days. Two inseminations, with a 24 h interval between them, were carried out on each sow. Pregnancy was determined at 35 days by ultrasound scan, and farrowing and litter size recorded. Pregnancy and farrowing data were very similar. The standard inseminating device produced farrowing rates of 91.1, 91.8 and 65.8% for insemination with 3, 2 and 1 billion spermatozoa, whereas the deep insemination device gave rates of 90.5, 90.5 and 86.9%. Only the 1 billion dose with the standard device was significantly different from the high dose control (P < 0.001). Similarly, the mean litter sizes with the standard device were 12.5, 12.6 and 10.3 and with the deep insemination device 12.3, 12.3 and 12.1. Only the 1 billion dose with the standard device was significantly lower (P < 0.001). None of the covariates differed significantly and there were no significant interactions with treatment. We conclude that transcervical insemination in the sow is simple, effective and safe, and allows the sperm dose to be reduced to 1 billion spermatozoa.     

Age of first breeding and incidence of dystocia and losses at parturition and post-partum in the indigenous Nigerian pig

Studies were carried out on the prevalence of dystocia and losses at parturition and post-partum following early mating and first breeding in 15 Nigerian indigenous pigs. Six were 8 months old at the time of their first farrowing, while nine were 11 or 12 months at the time of their first farrowing. Forty-six piglets were born, of which 11 died at birth (24%) and a further 18 during the next 7 days (total loss 63.0%). The six pigs that farrowed at 8 months of age had smaller mean litters and birth weights, a higher incidence of dystocia and higher piglet mortality at birth than those that farrowed later (32 with 91% survival). However, increased age at first farrowing did not reduce the high death rate during the first week (50% of piglets which survived at birth in both groups). This was attributed to starvation due to poor mothering ability following first farrowing since there was no agalactia or mastitis.     

Early piglet mortality in loose-housed sows related to sow and piglet behaviour and to the progress of parturition

The aim of the present study was to identify characteristics of sow behaviour and parturition related to early piglet mortality in loose-housed farrowing sows. Data from 152 farrowings that originated from three different herds with loose-housed sows during parturition were used. Graphical chain models were used to model the relationships between perinatal behaviour, periparturient individual conditions (time of day of parturition, rectal temperature 1–3 days postpartum) and causes of early piglet mortality. Modelling was based on the correlation between variables within herd and farrowing batch.The analysis showed that different causes of mortality were linked to different behavioural variables during the periparturient period and that they grouped into three independent categories. The first category was associated with stillbirth and death due to other causes. Stillbirth was positively related to the variation of the inter-birth interval and negatively related to the percentage of piglets that suckled during the first 8 h after birth of first piglet (BFP). Death due to other causes was negatively related to the suckling activity during the post-partal period (9–24 h after BFP). The second category was associated with piglet crushing, which was positively related to much lateral lying the last 4 h before BFP. Finally, the third category was associated with death due to lack of colostrums ingestion of colostrum, which was linked to the time of parturition and sow rectal temperature on days 1 and 2 after farrowing. Sows that gave birth during the morning compared to evening/night had more dead piglets due to lack of colostrums ingestion. Death due to lack of colostrums ingestion was also higher in sows with high rectal temperature on the day after BFP. The results further showed that litter size not only influenced mortality but also behavioural variables. High litter size was related to high nest building activity before BFP, low but more variable inter-birth intervals, and much lateral lying after BFP. The study points towards several areas of interest for further research that can help understand early piglet mortality. These include causes of variation in the progress of parturition, causes of individual differences in sow activity and responsiveness to piglets, and early management of farrowing. In addition, the study suggests possible indicators of problematic farrowings rendering liveborn piglets at risk. These include prepartum lateral lying in the sow, low suckling activity and rate of stillbirth.     

Modifications in the aggressive and ingestive behavior of the neonatal piglet as a result of prenatal elevation of cortisol in the dam

Ninety-eight piglets from 10 sows were used to study their neonatal agonistic and ingestive behavior after stimulation of the preparturient sow with adrenocorticotrophic hormone (ACTH). The sows were randomly assigned to either an ACTH or a control group on the 104th day of gestation. Sows in the ACTH group were catheterized and infused with 1IU porcine ACTH kg⁻¹ day⁻¹ in 1 l of saline. Control sows were similarly catheterized and infused with the same volume of saline, both treatments being maintained until parturition. A blood sample was collected daily from all sows. At birth piglets were weighed, bled and freed in the rear of the farrowing crate. They were then observed for the first 6 h of life to record their birth to suckle (BTS) interval. At the same time all instigator and victim interactions were recorded. Three subsequent blood samples were then collected from the piglets at 2, 4 and 6 h of life, and analyzed for glucose and cortisol. In both groups the concentration of plasma cortisol proved to be decreased (P<0.05) after birth while glucose increased within 2 h. The total number of instigations observed was higher (P<0.05) in pigs born to control sows than in those born to ACTH-treated sows. When values were expressed as instigations per pig or number of instigations relative to the total number of possible interactions within the litter, piglets of the ACTH group also exhibited less (P<0.05) aggressive instigations than those born to the control sows. Victimizations were not influenced either by treatment or sex. ACTH pigs had slightly shorter BTS intervals (P<0.05) than those in the control group. Females were lighter (P<0.05) than males at birth but they took less time to suckle than males. Accordingly it is concluded that the prenatal treatment of the sows with ACTH reduces the rate of agonistic interactions and tends to reduce the time required for first-time successful suckling.     

Effects of altering the dose and timing of triptorelin when given as an intravaginal gel for advancing and synchronizing ovulation in weaned sows

Previous studies have shown that triptorelin gel (TG) given intravaginally in gel form is effective for advancing the time of ovulation in weaned sows. Three experiments were performed to determine the effects of altering the dose and timing of administration of intravaginal TG for advancing and synchronizing ovulation in weaned sows. In all experiments, estrus was detected twice or three times daily and ultrasound was performed to determine ovulation at 8-hour intervals. In experiment 1, sows (n = 131) received intravaginal gel containing 0 (Placebo), 25, 100, or 200 μg of TG at 96 hours after weaning and sows were inseminated on each day of standing estrus. Wean-to-estrus interval and duration of estrus were correlated (P < 0.0001) with estrus duration longer in TG (P < 0.05) compared with Placebo. More sows ovulated (P < 0.001) by 48 hours after treatment with 200 (81%), 100 (64%), and 25 μg (63%) of TG compared with Placebo (42%). The farrowing rate and total pigs born did not differ (P > 0.10). In experiment 2, sows (n = 126) received 200 μg of TG at 72, 84, or 96 hours after weaning or were untreated (Control-96). Sows receiving TG were inseminated once 24 to 28 hours after treatment. Control-96 sows were inseminated on each day of standing estrus. Wean-to-estrus interval was not affected by treatment, but wean-to-ovulation interval was reduced (P < 0.05) by TG-72 and TG-84 compared with TG-96 and Control-96. More sows ovulated 40 hours after treatment (P < 0.001) with TG-72 (56.5%) and TG-84 (32.2%) compared with TG-96 and Control-96 (13%) and for all TG treatments 48 hours after treatment (64%) compared with Control-96 (34%, P < 0.05). The farrowing rate was lower (P < 0.05) for sows assigned to TG-72 and TG-84 compared with TG-96 and Control-96, whereas the number of liveborn pigs did not differ (P > 0.10). In experiment 3, sows (n = 113) were assigned to receive no treatment (Control), intravaginal gel alone (Placebo), or 200 μg of TG given intravaginally (OvuGel) at 96 hours after weaning. Wean-to-estrus interval did not differ, but the duration of estrus tended (P < 0.10) to be reduced with OvuGel compared with the other treatments. More sows ovulated (P < 0.001) by 48 hours after OvuGel treatment (79.1%) compared with Control (46.4%) and Placebo (37.9%) and by 56 hours (P < 0.05). The farrowing rate and the number of liveborn pigs did not differ among treatments. The results of these studies indicate that 200 μg of TG given intravaginally at 96 hours after weaning (OvuGel) synchronizes ovulation and results in fertility similar to Controls.     

Induction of parturition in swine with a prostaglandin analog and oxytoxin: A trial involving dose of oxytocin and parity

The purpose of this experiment was to compare a range of oxytocin doses in order to find the most suitable dose to improve predictability and precision of timing of PGF-induced parturition in sows. Sows randomly allotted to 6 groups - group size varying between 28 and 39 - were either untreated controls (group 1) or received an IM injection of 2 mg of the PGF-analog Alfaprostol (Vetem) on day 111 of pregnancy (day 0 = last day of standing heat), followed 20 h later by 0, 5, 10, 20 or 30 IU oxytocin, respectively (groups 2 - 6). Both length and variability of the time from injection of oxytocin to the onset of parturition decreased with increasing dose. The response was faster and more predictable with older sows than with first litter gilts. A disadvantage of higher doses of oxytocin was the necessity of manual aid (11 % in controls, 52 % with the maximum level of 30 IU oxytocin). Litter size, weight and percentage of piglets weaned and time from weaning to subsequent estrus were not affected by any of the treatments. An oxytocin dose of 20 IU applied 20 h after PGF appeared to give the most effective response, although this will occasionally necessitate manual assistance with parturition.     

Dosage response evaluation of luprostiol administered to pregnant sows

Two trials were completed to investigate the effects of luprostiol in swine. The first trial was to evaluate parturition induced by various dosages of luprostiol compared with those of lutalyse or vehicle. Sows were assigned by random allotment to one of the following treatments on Day 112 of gestation: Group A, control (0 mg luprostiol); Group B (1.88 mg luprostiol); Group C (3.75 mg luprostiol); Group D (7.5 mg luprostiol); Group E (15 mg luprostiol); Group F (10 mg lutalyse). All prostaglandin-treated groups farrowed earlier than the controls (P<0.05), with Groups D (26.3 h), E (31.0 h) and F (25.8 h) having the shortest treatment-to-first-pig intervals, and Groups A (76.0 h), B (54.4 h) and C (40.0 h) having the longest intervals. Luprostiol-treated sows had the shortest farrowing time (P<0.05; range = 3.2 to 3.9 h). Significant differences were found for the time (min) between births: Group A (32.1), Group B (28.4), Group F (35.5) took longer than Group C (20.2), Group D (21.0) and Group E (21.6). In a second trial, 20 crossbred pregnant sows received either vehicle or luprostiol (7.5 mg) on Day 112 of gestation. Progesterone concentrations declined rapidly (P<0.05) in luprotiol treated females but were unchanged in control females during the 24-h collection period. The results of these trials show 7.5 mg luprostiol to be the most effective dose for inducing farrowing.     

Fertility of sows injected with exogenous oestradiol and/or gonadotrophins to control post-weaning oestrus

In the first of two experiments 28 multiparous sows were allocated to one of the following treatments 2 days after weaning at approximately 35 days post partum: (1) untreated; (2) i.m. injection 10 μg oestradiol benzoate (OB)/kg body weight (b.wt.); and (3) i.m. injection 20 μg OB/kg b.wt. Sows were bred at first post-weaning oestrus and ovulation rate assessed at slaughter. The mean interval from weaning to oestrus in each group was: (1) 5.6 ± 0.2; (2) 4.7 ± 0.2; and (3) 4.7 ± 0.2 days; the mean ovulation rates in groups 1 and 2 (18.7 ± 0.6 and 17.4 ± 1.8, respectively) were significantly higher (P < 0.01) than that of 12.0 ± 1.7 for treatment 3 sows. Two untreated and one each of the treated sows were not cycling at slaughter.In the second experiment 75 multiparous sows weaned at 28 ± 3 days post partum (day 0) were evenly allocated with respect to parity to one of four treatment groups: (1) untreated; (2) i.m. injection 10 μg OB/kg b.wt. on day 2; (3) PG600 (400 iu PMSG + 200 iu hCG) injection subcutaneous day 0; and (4) combined PG600/OB treatment as in (2) and (3) above. Sows were bred naturally at the first post-weaning oestrus and fertility assessed at farrowing. Control animals had a significantly longer (P < 0.05) weaning to oestrus interval (4.53 ± 0.25 days) compared to treatment 2 (4.03 ± 0.13) treatment 3 (3.97 ± 0.12) and treatment 4 (3.81 ± 0.07) sows. Sows treated with PG600 alone showed a significant increase (P < 0.05) in numbers born live compared to pre-treatment values. A smaller and non-significant increase in numbers born live in control sows (probably related to increasing parity) was not observed in either OB- or PG600/OB-treated animals.These results suggest that with further modification of the treatments, a system may be developed for introducing fixed-time artificial insemination (AI) or mating as a means of controlling the reproductive performance of the weaned sow.     

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.     

Uterine and fetal asphyxia monitoring in parturient sows treated with oxytocin

Oxytocin is used to induce and control parturition, nevertheless, the increase of uterine contractions decreases blood flow and gaseous exchange through the womb predisposing to intra-partum mortality. The objective of the present study was to evaluate the effect of oxytocin on myometrial activity, fetal intrauterine hypoxia and postnatal asphyxia in sows during farrowing. Hybrid (n = 120) sows approaching the time of farrowing were randomly assigned in two groups of 60 animals each. Group I (G(1): control) was treated IM with saline solution and Group II (G(2)) was injected IM with oxytocin (1IU/6kg LW) as a single dose at birth of the first piglet. Both average number of myometrial contractions and intensity in G(2) were greater (P < 0.01) as compared with G(1). The mean of intra-partum stillbirths (IPS's) and those where fetal cardiac frequency (FCF) or heart beats, could not be detected after birth, were greater (P < 0.01) in G(2) as compared with G(1). The average decelerations of FCF known as dips II, which indicate severe hypoxia, was greater in G(2) (P < 0.01) as compared with that of G(1). There was a greater (P < 0.01) number of intra-partum stillbirths, stained with severe meconium in G(2) when compared with G(1). Oxytocin treatment increased (P < 0.01) the number of pigs born alive with ruptured umbilical cords and those with different grades of meconium staining on their skin. It was concluded that administration of oxytocin at the onset of parturition increased the myometrial activity, decreased fetal cardiac frequency, predisposed the rupture of umbilical cords and the degree of meconium staining, and increased intra-partum mortality.     

A behavioural scale to measure ease of farrowing in sows

Farrowing is one of the most critical phases in pig production, as it has an impact on neonatal pig survival. Assessing the ease of farrowing can improve the management of sows and thus increase litter survival. The aims of this study were: 1) to develop an ease of farrowing score (EFS) in sows based on the behaviour of the sows and their piglets, and 2) to determine the relationship between the EFS and productive, physiological, and subjective parameters. Eighty hybrid (Large White × Landrace) sows from first to seventh parity housed in individual crates were used. An EFS was constructed using the total duration of farrowing, the birth interval, the total time standing or sitting, the number of position changes during the day before and the day of farrowing, the sow posture at birth, the viability and the position of the piglets at birth (head or back born). Moreover, rectal temperature at 90 min after farrowing, a four categorical subjective visual assessment (VA) of farrowing and litter size (piglets born alive, stillborn and mummified foetus) were recorded. A common factor analysis model yielded five factors with an eigenvalue higher than 0.95 that accounted for 75.05% of the total variation between individuals. The three main factors were “farrowing duration”, “sow posture”, and “sow activity” of sows and explained 23.44%, 15.67%, and 14.23% of the variance, respectively. Primiparous sows had higher values for factor 3 (sow activity) than multiparous sows (P = 0.02). Sows without stillborn or mummification foetus showed higher values of EFS than sows with at least one stillborn or mummification foetus (P = 0.06 and 0.01, respectively). Sows that received a visual assessment of 3 and 4 showed higher values of EFS than sows that received a VA of 1 and 2 (P = 0.0017). The EFS appears to be a good behavioural scale to measure ease of farrowing in sows kept in individual farrowing crates. Duration of farrowing, sow position, and presence of stillborn piglets and mummified foetuses appear to be important ease of farrowing indicators.