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EnglishGestation length in swine has a considerable amplitude and both early and delayed parturition are common. This variation increases the occurrence of unassisted farrowing and could lead to a wide-ranging age at weaning for piglets born from one batch. Supervision of sow parturition is crucial to reduce mortality of neonate piglets. To facilitate assistance, induction of farrowing using prostaglandin F2α (PGF) has been widely used in batch farrowing systems, whereby synchronization would concentrate the time of farrowing, allowing for better organization of employees. However, a viable alternative method that can be implemented to manage farrowing is to sustain high progestagen levels in the final days of gestation and, consequently, prevent early parturition. Efficient techniques to delay farrowing such as using oral progestagen supplementation have been previously described, but are only recently being considered for commercial use. The present manuscript reviews publications regarding delaying parturition and discusses the use of intravaginal devices (IVDs) containing progestagen. There is limited data addressing the effect of progestagen treatment during gestation on productive and reproductive performance. Therefore, future studies should focus on improving synchronization protocols following progestagen supplementation and evaluating piglet viability and sow fertility, before widely using progestagen supplementation to manipulate parturition. Key words: farrowing induction; intravaginal device; progestagen; early parturiton portuguesComo a duracao da gestacao de suinos pode ter ampla variacao, e comum a ocorrencia de partos antecipados ou gestacoes prolongadas. Isso aumenta as chances de partos sem assistencia e leva a uma grande variacao de idade dos leitoes dentro do lote de producao. Portanto, a supervisao do parto e indispensavel para reduzir as perdas neonatais. Para facilitar o auxilio aos leitoes, a inducao do parto com prostaglandina F2α (PGF) e eficaz e amplamente utilizada, sendo indicada para concentrar os partos em momentos mais adequados, preferencialmente durante o horario com maior disponibilidade de colaboradores. Uma alternativa viavel e manipular o momento do parto, atraves da manutencao de niveis plasmaticos elevados de progestageno durante o final da gestacao, a fim de evitar partos antecipados. Formas eficientes de evitar o parto atraves de suplementacao oral de progestagenos foram descritas ha decadas, mas apenas recentemente tem sido cogitada a utilizacao comercial. A presente revisao aborda estudos disponiveis na literatura relacionados ao protelamento do parto, incluindo a utilizacao de dispositivos intravaginais (DIVs) impregnados com progestageno. Sao poucos os dados disponiveis relacionados ao uso de progestagenos na gestacao com indices produtivos e reprodutivos. Portanto, alguns pontos ainda devem ser melhor avaliados, especialmente com relacao a determinacao da sincronia dos partos apos o fim da suplementacao com progestagenos, a viabilidade dos neonatos e a fertilidade subsequente das femeas antes da ampla adocao desta tecnica. Palavras-chave: inducao de parto; dispositivo intravaginal; progestageno; parto antecipado.

The researches were made to induce and synchronize the farrowing during the working schedule. In the trial we have been testing two hormonal products Estrumate and Prosolvin to two groups of gilts, in the 113th day of gestation. After the administration of the prostaglandin synthetic analogs we follow up the time when the gilts were farrowing, the prolificacy and the parturition loss. The percent of gilts that were farrowing during the working schedule was 48.84 at the group with Estrumate and 50.00 at the group with Prosolvin (difference non significant, χ 2 test, p>0.05). The percent of gilts that were farrowing after the working schedule 32.56 at the group with Estrumate and 16.67 at the group with Prosolvin (difference non significant, χ 2 test, p>0.05). The prolificacy was bigger for the group that were farrowing during the working schedule (10.57±0.60 pigs/gilt for the group with Estrumate and 11.43±0.12 pigs/gilt for the group with Prosolvin) comparing with the gilts that were not farrowing during the working schedule (10.21±0.79 for the group with Estrumate and 10.75±0.24 pigs/gilt for the group with Prosolvin) and significant (t test p0.05).

Inducing parturition in the sow can be used to improve farrowing supervision, which may lead to more weaned piglets. However, if not applied properly, it may lead to premature delivery. Therefore, induction of parturition should be performed not earlier than two days before the average gestation length of the sows of a farm. To induce parturition, different protocols, such as single administration of prostaglandins, double administration of prostaglandin with 6-hour interval (split-dose technique) and a combination of prostaglandins and oxytocin 24 hours later, and different administration routes, such as intramuscular injection in the neck region and injection in the vulvar region, can be used. Other strategies exist but they are less effective and/or less frequently used. A single injection of prostaglandins results in 60% of the sows farrowing within working hours (22-32 hours after injection). Using the split-dose technique or the combination of prostaglandins and oxytocin 24 hours later, the percentage increases with 20%. The use of oxytocin however increases the risk of asphyxia in the piglets, especially in case of inappropriate use. Whether farrowing induction should be applied and which protocol used depend on the herd and the preferences of the farmer.

International audience; Hormonal changes involved in the farrowing process partly control the initiation of lactation. Inducing farrowing by injection of prostaglandins may alter the normal prepartum hormonal “cascade.” The aim of the study was to investigate the consequences of farrowing induction on colostrum yield and composition, as well as newborn piglet growth. Gilts were treated with 2 mg of alfaprostol on d 113 of gestation (induced farrowing, IF, n = 9) or were injected with 1 mL of a saline solution (natural farrowing, NF, n = 11). Colostrum production was estimated during 24 h, starting at the onset of parturition, based on piglet weight gains. Colostrum samples were collected during the 36 h following the onset of parturition. Blood samples were collected from sows as of d 112 of pregnancy until d 2 postpartum (d 0 being the day of parturition). Piglet blood samples were obtained at birth, on d 1, and on d 21. Litter size and litter weight at birth did not differ between groups (P > 0.10). Farrowing induction did not influence (P > 0.10) colostrum yield (3.96 ± 0.20 kg) or piglet weight gain during d 1 postpartum (116 ± 8 g). At the onset of farrowing (T0), lactose content in colostrum was greater in IF sows than in NF sows (P < 0.05), whereas colostrum ash and protein contents were lesser (P < 0.05) in IF sows. Concentrations of IgG in colostrum were similar in both groups of sows, while concentrations of IgA at T0 were lower in IF than in NF sows (P < 0.01). Overall, endocrine changes in blood from d -2 until d 2 (cortisol, prolactin, progesterone, and estradiol-17β) were not altered by farrowing induction (P > 0.10), but 1 h after the injection of alfaprostol, IF sows had greater circulating concentrations of prolactin (P < 0.01) and cortisol (P < 0.10) than NF sows. The greater concentration of lactose in colostrum from IF sows could be attributed to this transient increase in prolactin and cortisol. At birth, concentrations of white blood cells were less in piglets born from IF sows (P < 0.01). On d 1 and d 21, piglets from IF sows had similar IgG concentrations in plasma to piglets from NF sows (P > 0.1). In conclusion, farrowing induction at 113 d of pregnancy induced transient hormonal changes in sows and alterations in colostrum composition, without significantly affecting colostrum yield. It also modified some hematological variables of piglets at birth.