Risk factors associated with stillbirth in sows / Fatores de risco associados à natimortalidade em fêmeas suínas

In this study, the risk factors associated with stillbirth in sows were identified and their odds ratio assessed. For this purpose, 587 farrowings on Farm A and 929 on Farm B were monitored, and the sow parity, body condition score, farrowing duration, total number of piglets born, numbers of live births, stillbirths, and mummified piglets, obstetric interventions, and piglet sex and weight were recorded. At the end of farrowing, piglets classified as stillborn were necropsied to confirm the diagnosis. Consequently, 5.49% of the piglets on Farm A and 5.10% of those on Farm B were stillborn. On both farms, sows with a high parity, prolonged farrowing, and a large litter size had the highest odds ratio of stillbirths. On Farm B, farrowing intervention through the use of vaginal palpation and oxytocin increased the odds of stillbirth by 1.7 and 2.5 times, respectively. Heavy litters increased the odds of stillbirth by 1.4 times. Additionally, low-birth-weight piglets were 2.3 and 3.1 times more likely than their medium-birth-weight and high-birth-weight counterparts, respectively, to be stillborn. In conclusion, on both farms, the risk factors associated with stillbirth were a high parity, a large litter size, and prolonged farrowing.

O objetivo deste estudo foi avaliar os fatores de risco associados ao nascimento de natimortos em fêmeas suínas e a razão de chance para a sua ocorrência. Foram acompanhados 587 partos na granja A e 929 na granja B onde foram registrados: ordem de parto, escore de condição corporal, duração do parto, total de nascidos, nascidos vivos, natimortos, mumificados, intervenções ao parto, peso e o sexo dos leitões. Ao final do parto foi realizada necropsia dos leitões classificados como natimortos a fim de confirmar o diagnóstico. A ocorrência de leitões natimortos foi de 5,49% e 5,10% na granja A e B, respectivamente. Fêmeas de maior ordem de parto, com partos prolongados e leitegadas mais numerosas apresentaram maior chance da ocorrência de leitões natimortos em ambas as granjas. Na granja B a necessidade de intervenção ao parto através do uso de ocitocina e palpação vaginal aumentaram a chance da presença de leitões natimortos em 1,7 e 2,5 vezes, respectivamente. Leitegadas pesadas aumentaram em 1,4 vezes as chances de ocorrência de leitões natimortos. No entanto, leitões com menor peso ao nascer aumentam em 2,3 vezes as chances de natimortos, quando comparadas a leitões de peso intermediário, e 3,1 vezes em relação a leitões com maior peso de nascimento. Os fatores de risco associados à ocorrência de natimortos nas duas granjas foram a ordem de parto elevada, leitegadas numerosas e partos prolongados.

Recent advances in pig reproduction: 2. Higher litter size / Recentes avanços na reprodução suina: 2. Leitegadas maiores

In the past 30 years, sows have been successfully selected for increased litter size. This review discusses the consequences of this selection for the reproductive physiology of sows, including the consequences for litter characteristics at birth. It also discusses breeding and management opportunities to deal with these modern genetics.(AU)

Recent advances in pig reproduction: 2. Higher litter size / Recentes avanços na reprodução suina: 2. Leitegadas maiores

In the past 30 years, sows have been successfully selected for increased litter size. This review discusses the consequences of this selection for the reproductive physiology of sows, including the consequences for litter characteristics at birth. It also discusses breeding and management opportunities to deal with these modern genetics.

Recent advances in pig reproduction: 1. Shorter weaning-to-oestrus interval / Recentes avanços na reprodução suína: 1. Intervalos mais curtos da desmama-estro

In the past 30 years, sows have been successfully selected for a shorter weaning-to-oestrus interval and increased litter size. This review discusses the consequences of this selection for the reproductive physiology of sows, including the consequences for litter characteristics at birth. It also discusses breeding and management opportunities to deal with these modern genetics.(AU)

Recent advances in pig reproduction: 1. Shorter weaning-to-oestrus interval / Recentes avanços na reprodução suína: 1. Intervalos mais curtos da desmama-estro

In the past 30 years, sows have been successfully selected for a shorter weaning-to-oestrus interval and increased litter size. This review discusses the consequences of this selection for the reproductive physiology of sows, including the consequences for litter characteristics at birth. It also discusses breeding and management opportunities to deal with these modern genetics.

Combined treatment of eCG and a non-selective inhibitor of phosphodiesterases for enhancing reproductive performance in ewes

The aim of this study was to evaluate the effect of the non-selective phosphodiesterase inhibitor 3- isobutyl-1-methyl-xanthine (IBMX) given concomitantly with eCG on reproductive performance of ewes. In trial 1, eighty ewes were allocated into 8 groups (AC, A1, A2, A3 and DC, D1, D2, D3). Oestruses were synchronized by progestagen sponges. At sponges removal all ewes of A groups received 400 IU of eCG. Concomitantly with eCG, ewes of groups A1, A2 or A3 received IMBX at the dose of 2.5, 5.0 or 25.0 mg, respectively. Ewes of D1, D2 or D3 groups received only IBMX at the same doses, respectively; in each case, ewes of AC or DC groups were controls (C). In trial 2, one hundred eighteen ewes were allocated into 4 groups (BC1, B1 and BC2, B2). Oestruses were synchronized by progestagen sponges. At sponges removal ewes of BC1 or B1 received 200 IU of eCG, while ewes of BC2 or B2 groups received 100 IU. At the same time only ewes of B1 or B2 groups received 2.5 mg IBMX. In both trials, 48 hours after hormonal treatment, ewes were mated. In trial 1, pregnancy or lambing rate did not differ among A or D groups (P > 0.05). Total lambs per ewe were significantly higher in A1 compared to AC, A2, A3 or D1 groups (P 0.05). In trial 2, pregnancy or lambing rate did not differ among B groups (P > 0.05). Total lambs per ewe were significantly higher (P < 0.05) in B1 and B2 compared to BC1 and BC2 groups, respectively. These results indicate that IBMX combined with eCG at the end of an oestrus synchronization treatment improves litter size probably by increasing ovulation rate in ewes. This latter effect seems to be mainly dependent on the amount of gonadotrophins used.

Combined treatment of eCG and a non-selective inhibitor of phosphodiesterases for enhancing reproductive performance in ewes

The aim of this study was to evaluate the effect of the non-selective phosphodiesterase inhibitor 3- isobutyl-1-methyl-xanthine (IBMX) given concomitantly with eCG on reproductive performance of ewes. In trial 1, eighty ewes were allocated into 8 groups (AC, A1, A2, A3 and DC, D1, D2, D3). Oestruses were synchronized by progestagen sponges. At sponges removal all ewes of A groups received 400 IU of eCG. Concomitantly with eCG, ewes of groups A1, A2 or A3 received IMBX at the dose of 2.5, 5.0 or 25.0 mg, respectively. Ewes of D1, D2 or D3 groups received only IBMX at the same doses, respectively; in each case, ewes of AC or DC groups were controls (C). In trial 2, one hundred eighteen ewes were allocated into 4 groups (BC1, B1 and BC2, B2). Oestruses were synchronized by progestagen sponges. At sponges removal ewes of BC1 or B1 received 200 IU of eCG, while ewes of BC2 or B2 groups received 100 IU. At the same time only ewes of B1 or B2 groups received 2.5 mg IBMX. In both trials, 48 hours after hormonal treatment, ewes were mated. In trial 1, pregnancy or lambing rate did not differ among A or D groups (P > 0.05). Total lambs per ewe were significantly higher in A1 compared to AC, A2, A3 or D1 groups (P < 0.05), but did not differ among D groups (P > 0.05). In trial 2, pregnancy or lambing rate did not differ among B groups (P > 0.05). Total lambs per ewe were significantly higher (P < 0.05) in B1 and B2 compared to BC1 and BC2 groups, respectively. These results indicate that IBMX combined with eCG at the end of an oestrus synchronization treatment improves litter size probably by increasing ovulation rate in ewes. This latter effect seems to be mainly dependent on the amount of gonadotrophins used.(AU)

AVALIAÇÃO LABORATORIAL E DO CORTISOL MATERNO E FETAL EM CADELAS PARTURIENTES COM DIFERENTES TAMANHOS DE NINHADAS

Conhecer a fisiologia e endocrinologia do parto ajuda a melhorar e a otimizar os resultados no pósparto. Entretanto, na espécie canina, ainda pouco se conhece sobre os hormônios envolvidos no seu desencadeamento, assim como as alterações hematológicas e bioquímicas e suas relações com o tamanho da ninhada. Objetivou-se avaliar as concentrações séricas de cortisol materno e do líquido amniótico fetal e os parâmetros hematológicos e bioquímicos de cadelas parturientes com diferentes tamanhos de ninhadas. Foram avaliadas 50 cadelas, no momento da expulsão do primeiro feto, e o líquido amniótico de 23 neonatos. A concentração média de cortisol sérico foi de 81,0 ± 41,8 ng/mL, e de líquido amniótico 11,34 ± 5,61 ng/mL. Os parâmetros hematológicos e bioquímicos encontrados foram VG (41,35 ± 4,55%), hemácias (5,75 ± 0,94 x 106 cels/ uL), hemoglobina (13,29 ± 1,50 g/dL), leucócitos totais (19.220 ± 4.517,05 céls/mL), plaquetas (448.550 ± 201.254,1 céls/uL), proteína total (7,81 ± 1,18 g/dL), cálcio (10,7 ± 2,62 mg/dL), magnésio (2,54 ± 0,57 mg/dL) e glicose (101,31 ± 26,42 mg/dL). Não houve correlação significativa entre cortisol sérico e tamanho da ninhada (p>0,05) porém as parturientes de grande porte apresentaram cortisol sérico menor que as de pequeno porte (p=0,0075), e animais da raça Pug apresentaram menores concentrações de cortisol sérico quando comparados com animais da raça Yorkshire (p=0,0214). Foi observada correlação entre cortisol sérico e cortisol do líquido amniótico (p=0,02). Não houve correlação entre tamanho de ninhada com as variáveis hematológicas e bioquímicas (p>0,05). As cadelas primíparas apresentaram mais eosinófilos que as multíparas (p=0,03), e animais de grande porte apresentaram menos linfócitos quando comparados com animais de pequeno porte (p=0,02). Também foi observado que animais de grande porte apresentam maiores concentrações de proteína total do que animais de pequeno porte (p=0,04). Quanto a raça, animais da raça Shih Tzu apresentaram mais linfócitos que as demais raças (p = 0,006), sendo que essa mesma raça apresentou mais plaquetas que as fêmeas Pug (p=0,006). Animais da raça Golden Retriever apresentaram maiores concentrações de Mg quando comparado às da raça Pug (p=0,04), e as cadelas da raça Pug apresentaram menores concentração de glicose sérica em relação as outras raças (p=0,0050). Também foi observada influência do peso da placenta no peso ao nascimento, sendo que a cada 1,0g de placenta há aumento de 2,5g no peso do neonato (p=0,0002). Conclui-se que o tamanho da ninhada não interfere nas concentrações do cortisol sérico, porém variáveis como porte e raça foram importantes para explicar a diferença de cortisol sérico entre as fêmeas. Ordem de parto, porte da fêmea e raça influenciam nas concentrações de eosinófilos, linfócitos e plaquetas, bem como de proteína total, magnésio e glicose das parturientes. O peso ao nascimento é influenciado pelo peso da placenta.

The knowledge of physiology and endocrinology of bitch´s parturition helps to improve and optimize postpartum outcomes. However, in the canine species, it still not known about the hormones involved in triggering parturition, as well as the hematological and biochemical changes and their relationships with the size of the litter. The objective of this study was to evaluate the serum concentrations of maternal cortisol and fetal amniotic fluid cortisol, and blood and biochemical parameters of parturient bitches with different litter sizes. Blood samples were collected from fifty bitches at the time of the expulsion of the first fetus, and amniotic fluid from 23 newborns. The mean concentration of serum cortisol was 81.0 ± 41.8 ng/mL, and of amniotic fluid 11.34 ± 5.61 ng/mL. The hematological and biochemical parameters were VG (41.35 ± 4.55%), RBC (5.75 ± 0.94 x 106 cells/uL), hemoglobin (13.29 ± 1.50 g/dL), WBC (19,220 ± 4,517.05 cells/mL), platelets (448,550 ± 201,254.1 cells/uL), total protein (7.81 ± 1.18 g/dL), calcium (10.7 ± 2.62 mg/uL), magnesium (2.54 ± 0.57 mg/dL) and glucose (101.31 ± 26.42 mg/dL). There was no significant correlation between serum cortisol and litter size (p>0.05) but large breeds had lower mean serum cortisol than small ones (p=0.0075), and Pug bitches had lower concentrations of serum cortisol when compared to Yorkshire bitches (p=0.0214). It was observed correlation between serum cortisol and amniotic fluid cortisol (p=0.02). There was no correlation between litter size and hematological and biochemical variables (p>0.05). Primiparous bitches presented more eosinophils when compared to multiparous bitches (p=0.03) and large breeds had fewer lymphocytes when compared to small breeds (p=0.02). It was also observed that large breeds had more total protein than small breeds (p=0.04). As for breed, it was observed that Shih Tzu had more lymphocytes when compared to other breeds (p = 0.006), and this same breed had more platelets when compared to Pug (p = 0.006). Golden Retriever had higher Mg concentrations when compared to Pug (p=0.04), and Pug had lower serum glucose concentration compared to other breeds (p=0.0050). The influence of placental weight on neonatal weight was also observed, with every 1.0g of placenta increasing by 2.5g in the newborn's weight (p=0.0002). It was concluded that litter size did not affect serum cortisol concentrations, but size and breed were important to explain the difference in serum cortisol among females. Parity order, breed size and breed influenced the concentrations of eosinophils, lymphocytes and platelets, as well as total protein, magnesium and glucose in parturients. Neonatal weight was influenced by placental weight.

Parâmetros genéticos para características de prolificidade nas raças Landrace e Large White / Genetic parameters for prolificacy in Landrace and Large White breeds

Dados de suínos das raças Landrace (LD) e Large White (LW) foram utilizados para estimar componentes de variância para número total de leitões nascidos (NTN), nascidos vivos (NV) e de leitões vivos ao quinto dia (LV5). Usou-se o método da máxima verossimilhança restrita (REML) para estimar componentes de variância. O modelo misto incluiu os efeitos fixos de mês e ano de nascimento e da inseminação da porca e ordem de parto. Análises unicaracterísticas incluíram os efeitos genético direto, genético materno e de ambiente permanente. Análises multicaracterísticas foram feitas para estimar correlações genéticas. Os modelos unicaracterísticas foram comparados e o que continha apenas o efeito genético direto foi considerado o mais adequado. As estimativas de herdabilidade para NTN foram de 0,15 para LW e de 0,08 a 0,12 para LD, dependendo do modelo, para NV foram de 0,14 para LW e de 0,05 a 0,12 para LD, e para LV5, variaram de 0,11 a 0,12 para LW e de 0,03 a 0,08 para LD. As correlações fenotípicas e genéticas entre as três características foram altas e favoráveis. Conclui-se que a seleção para aumento do LV5 pode ser uma via interessante para o aumento do tamanho da leitegada, da sobrevivência de leitões e da habilidade materna em suínos(AU)

Data from Landrace (LD) and Large White (LW) sows were analyzed to estimate variance components for total number of piglets born (NTN), number of piglets born alive (NV) and number alive on day 5 after birth (LV5). REML mixed model equations included the fixed effects of sow´s month and year of birth and insemination and farrowing order. Univariate analyses included, alternatively, direct genetic, maternal genetic and permanent environmental effects. Multiple trait analysis was performed to estimate genetic correlations among the traits. Comparisons between univariate models indicated that the model containing only direct genetic effect was the most appropriate for parameter estimation. Estimates of heritability for NTN were 0.15 in LW and ranged from 0.08 to .12 in LD, 0.14 in LW, from 0.05 to 0.12 in LD for NV, from 0.11 to 0.12 in LW, and from 0.03 to 0.08 in LD for LV5. Phenotypic and genetic correlations among traits were high and favorable. Results suggest that selection for LV5 is an interesting alternative way to increase litter size, piglet survival and maternal ability in swine(AU)

Effect of body development from first insemination to first weaning on performance and culling until the third farrowing of Landrace x Large White swine females / Efeito do desenvolvimento corporal desde a primeira inseminação até o primeiro desmame no desempenho e descarte até o terceiro parto de fêmeas suínas Landrace x Large White

The aim of this study was to verify the association of sow body weight development until the 1st weaning with reproductive performance, piglet production and culling rate until the 3rd farrowing in 196 primiparous sows using logistic regression models. Each 10kg increase in weight gain in the 1stpregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.70), weight at the 1st weaning (OR= 0.73) or weight gain from the 1startificial insemination (AI) to the 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long weaning-to-oestrus interval - WOI (>5 days). An increasing lactation length and an increase in the number of weaned piglets were responsible for respectively decreasing (OR= 0.77-0.80, per day of lactation) and increasing (OR= 1.52-1.59, per piglet weaned) the percentage of sows with long WOI. Sows with <159.5kg at weaning had higher odds of non-farrowing (NFR) compared to sows with >170kg (OR= 4.73). Sows with <17.5kg of gain from the 1st AI to the 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30kg. Each additional lactation day decreased the NFR (OR= 0.74). Females weighing <139kg at the 1st AI had higher percentages of small numbers of total born in the second parity (STB2, OR= 2.00) and over three parities (OR= 3.28) compared to those weighing ≥139kg. Sows with weight gain <25kg at the 1st pregnancy had higher odds of STB2 (OR= 3.01) compared to sows gaining >35kg. Each 10kg of increase in weight at the 1st weaning or in weight gain from the 1st AI to the 1st weaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling for reproductive reasons (OR= 0.57 and 0.61, respectively). The culling rate until the 3rdfarrowing was also increased in sows with a smaller first litter size. The results show that not only reaching a minimum weight at the 1st AI but also having an adequate body weight gain until the 1st weaning is important for the reproductive performance, productivity and retention of Landrace x Large White Danbred sows in the herd.(AU)

O objetivo do estudo foi verificar, com modelos de regressão logística, a associação entre características de desenvolvimento corporal até o 1º desmame com o desempenho reprodutivo, produção de leitões e taxa de remoção até o 3º parto de 196 fêmeas suínas primíparas. Houve redução nas chances de as fêmeas terem intervalo desmame-estro (IDE) longo (>5 dias) a cada 10kg de aumento no ganho de peso na 1ª gestação - GPG1 (razão de chance - RC = 0,63), peso no 1º parto - PP1 (RC= 0,70), peso no 1º desmame - PD1 (RC= 0,73) ou ganho de peso da 1ª inseminação artificial (IA) ao 1º desmame - GPIAD1 (RC= 0,67). O percentual de porcas com IDE longo reduziu com o aumento da duração da lactação (RC= 0,77-0,80, por dia de lactação) e aumentou com o aumento no número de leitões desmamados (RC= 1,52-1,59, por leitão desmamado). Porcas com <159,5kg ao desmame tiveram maior chance de não parir (NP) em comparação a porcas com >170 kg (RC= 4,73). Porcas com <17,5kg de GPIAD1 tiveram maior chance (RC= 4,88) de NP do que porcas ganhando >30kg. O aumento da duração da lactação reduziu a chance de NP (RC= 0,74, para cada dia). Fêmeas com <139kg na 1ª IA tiveram maior chance de terem leitegada pequena no segundo parto - LPSP (RC= 2,00) ou ao longo de 3 partos (RC= 3,28), em comparação às fêmeas com ≥139kg. Fêmeas com GPG1 <25kg tiveram maior chance de LPSP (RC= 3,01) do que fêmeas com >35kg. Houve diminuição na taxa geral de descarte (RC= 0,71 e 0,73, respectivamente) e descarte por causas reprodutivas (RC= 0,57 e 0,61, respectivamente) para cada 10kg de aumento no PD1 e GPIAD1. A taxa de descarte até o 3º parto também aumentou nas porcas com menor leitegada no primeiro parto. Os resultados mostram que, além de atingir um peso mínimo na 1ª IA, o ganho de peso entre a 1ª IA e o primeiro desmame é importante para o desempenho reprodutivo, produtividade e retenção de fêmeas Danbred Landrace x Large White no rebanho.(AU)

Effects of exposure to halothane, isoflurane, and sevoflurane on embryo viability and gestation in female mice / Efeitos da exposição ao halotano, isofluorano, e sevofluorano na viabilidade embrionária e gestação em fêmeas de camundongos

Although the negative effects of inhalation anaesthetics on fertility have been known for a while, the stages during the reproductive cycle at which these effects occur and the mechanisms of action are largely unknown. This study aimed to evaluate the effects of acute exposure of female mice to halothane, isoflurane, and sevoflurane prior to mating. BALB/c female mice (n=160) were allocated in groups of 20 to halothane (HG), isoflurane (IG), sevoflurane (SG), and oxygen/sham (SH) treatment groups and their respective control groups (CGs). The mice were exposed to 1 minimum alveolar concentration (MAC) of the corresponding anaesthetic or oxygen for 4 h/day over 5 consecutive days. Two days after exposure, females were mated with males (ratio 2:1 female/male) for five consecutive days. Every morning, females were checked for the presence of vaginal plugs. Half of the females that exhibited plugs were euthanised 72 h later for embryo evaluation. The remaining females were euthanised on the 14th day of pregnancy for foetal evaluation. A low number of morulae and total embryos (morulae + blastocysts) were observed in the HG (P 0.05). The number of implantations was lower in the HG (6.0) compared with the IG (11.8) and SG (12.4) (P 0.05). Exposure to halothane is not recommended for use in female mice prior to mating procedures because it leads to decreased embryo production...(AU)

Embora os efeitos negativos dos anestésicos inalatórios na fertilidade já foram descritos há algum tempo, os estágios durante o ciclo reprodutivo em que estes efeitos ocorrem bem como os mecanismos de ação ainda permanecem desconhecidos. Os objetivos deste estudo foram avaliar os efeitos da exposição aguda em fêmeas de camundongos ao halotano, isofluorano, e sevofluorano prévio ao acasalamento. Fêmeas de camundongos BALB/c (n=160) foram alocadas em grupos de 20 aos tratamentos halotano (HG), isofluorano (IG), sevofluorano (SG), oxigênio (SH), e seus respectivos grupos controle (CGs). As fêmeas de camundongos foram expostas a uma concentração alveolar mínima (CAM) do anestésico correspondente ou a oxigênio por 4 horas diárias durante 5 dias consecutivos. Após dois dias do fim da exposição às fêmeas foram acasaladas com os machos (proporção 2:1 fêmea/macho) durante 5 dias consecutivos. A cada manhã, as fêmeas foram avaliadas para a observação da presença de plug vaginal. Metade das fêmeas que exibiam plug foram submetidas à eutanásia após 72 horas para avaliação embrionária. As fêmeas restantes foram eutanasiadas no 14º dia de gestação para avaliação fetal. No HG foi observado um menor número de mórulas e embriões totais (mórulas + blastocistos) (P 0,05). O número de implantações foi menor no HG (6,0) comparado ao IG (11,8) e SG (12,4) (P 0,05). A exposição ao halotano não...(AU)

Effect of body development from first insemination to first weaning on performance and culling until the third farrowing of Landrace x Large White swine females / Efeito do desenvolvimento corporal desde a primeira inseminação até o primeiro desmame no desempenho e descarte até o terceiro parto de fêmeas suínas Landrace x Large White

The aim of this study was to verify the association of sow body weight development until the 1st weaning with reproductive performance, piglet production and culling rate until the 3rd farrowing in 196 primiparous sows using logistic regression models. Each 10kg increase in weight gain in the 1st pregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.70), weight at the 1st weaning (OR= 0.73) or weight gain from the 1st artificial insemination (AI) to the 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long weaning-to-oestrus interval - WOI (>5 days). An increasing lactation length and an increase in the number of weaned piglets were responsible for respectively decreasing (OR= 0.77-0.80, per day of lactation) and increasing (OR= 1.52-1.59, per piglet weaned) the percentage of sows with long WOI. Sows with <159.5kg at weaning had higher odds of non-farrowing (NFR) compared to sows with >170kg (OR= 4.73). Sows with <17.5kg of gain from the 1st AI to the 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30kg. Each additional lactation day decreased the NFR (OR= 0.74). Females weighing <139kg at the 1st AI had higher percentages of small numbers of total born in the second parity (STB2, OR= 2.00) and over three parities (OR= 3.28) compared to those weighing ≥139kg. Sows with weight gain <25kg at the 1st pregnancy had higher odds of STB2 (OR= 3.01) compared to sows gaining >35kg. Each 10kg of increase in weight at the 1st weaning or in weight gain from the 1st AI to the 1st weaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling for reproductive reasons (OR= 0.57 and 0.61, respectively). The culling rate until the 3rd farrowing was also increased in sows with a smaller first litter size. The results show that not only reaching a minimum weight at the 1st AI but also having an adequate body weight gain until the 1st weaning is important for the reproductive performance, productivity and retention of Landrace x Large White Danbred sows in the herd.(AU)

O objetivo do estudo foi verificar, com modelos de regressão logística, a associação entre características de desenvolvimento corporal até o 1º desmame com o desempenho reprodutivo, produção de leitões e taxa de remoção até o 3º parto de 196 fêmeas suínas primíparas. Houve redução nas chances de as fêmeas terem intervalo desmame-estro (IDE) longo (>5 dias) a cada 10kg de aumento no ganho de peso na 1ª gestação - GPG1 (razão de chance - RC = 0,63), peso no 1º parto - PP1 (RC= 0,70), peso no 1º desmame - PD1 (RC= 0,73) ou ganho de peso da 1ª inseminação artificial (IA) ao 1º desmame - GPIAD1 (RC= 0,67). O percentual de porcas com IDE longo reduziu com o aumento da duração da lactação (RC= 0,77-0,80, por dia de lactação) e aumentou com o aumento no número de leitões desmamados (RC= 1,52-1,59, por leitão desmamado). Porcas com <159,5kg ao desmame tiveram maior chance de não parir (NP) em comparação a porcas com >170 kg (RC= 4,73). Porcas com <17,5kg de GPIAD1 tiveram maior chance (RC= 4,88) de NP do que porcas ganhando >30kg. O aumento da duração da lactação reduziu a chance de NP (RC= 0,74, para cada dia). Fêmeas com <139kg na 1ª IA tiveram maior chance de terem leitegada pequena no segundo parto - LPSP (RC= 2,00) ou ao longo de 3 partos (RC= 3,28), em comparação às fêmeas com ≥139kg. Fêmeas com GPG1 <25kg tiveram maior chance de LPSP (RC= 3,01) do que fêmeas com >35kg. Houve diminuição na taxa geral de descarte (RC= 0,71 e 0,73, respectivamente) e descarte por causas reprodutivas (RC= 0,57 e 0,61, respectivamente) para cada 10kg de aumento no PD1 e GPIAD1. A taxa de descarte até o 3º parto também aumentou nas porcas com menor leitegada no primeiro parto. Os resultados mostram que, além de atingir um peso mínimo na 1ª IA, o ganho de peso entre a 1ª IA e o primeiro desmame é importante para o desempenho reprodutivo, produtividade e retenção de fêmeas Danbred Landrace x Large White no rebanho.(AU)

Effect of birth weight and litter size on the performance of landrace gilts until puberty

Background: The selection for larger litter size has resulted in reduction of average birth weight and in increase of withinlitter birth weight variation in pigs. Birth weight is one of the most important factors affecting the survival and performanceof piglets until weaning. The aim of this study was to evaluate the effect of litter size into which gilts were born and theirindividual birth weight on mortality and culling rate until the time of selection, as well as on puberty onset.Materials, Methods & Results: Female Landrace piglets (n = 1525) were identifi ed and weighed within 18 h after birth.They were also weighed at weaning (n = 1379), and at the end of the nursery (n = 1198) and rearing phases (n = 940).Three classes of litter size were created: Small LS (7-11 piglets), Intermediate LS (12-13 piglets) and Large LS (14-19piglets). Gilts were also separated in three classes according to their birth weight: Low BW (530-1200 g), IntermediateBW (1205-1600 g) and High BW (1605-2535 g). When compared to High BW gilts, the risk of death until weaning wasgreater (P < 0.05) in Low BW gilts from Intermediate LS and Large LS litters, but not in Low BW gilts from Small LSlitters. Within the Low BW class, the risk of mortality until weaning was greater or tended to be greater if gilts were bornin Intermediate LS (P < 0.05) or Large LS (P = 0.079) litters compared to those from Small LS litters. Average dailyweight gain (ADWG), and weights at 22, 75 and 155 days of age, increased according to the increase in birth weight(P < 0.05). There was no effect of birth weight or litter size on mortality and culling rate, during nursery and rearing phases,and on percentages of gilts in anoestrous until 30 days after boar stimulation (P > 0.05). The risk of not being selected forbreeding was greater (P < 0.09) in Light BW gilts than in High BW gilts in all litter size classes. Low BW gilts were olderat the beginning...(AU)

Effect of birth weight and litter size on the performance of landrace gilts until puberty

Background: The selection for larger litter size has resulted in reduction of average birth weight and in increase of withinlitter birth weight variation in pigs. Birth weight is one of the most important factors affecting the survival and performanceof piglets until weaning. The aim of this study was to evaluate the effect of litter size into which gilts were born and theirindividual birth weight on mortality and culling rate until the time of selection, as well as on puberty onset.Materials, Methods & Results: Female Landrace piglets (n = 1525) were identifi ed and weighed within 18 h after birth.They were also weighed at weaning (n = 1379), and at the end of the nursery (n = 1198) and rearing phases (n = 940).Three classes of litter size were created: Small LS (7-11 piglets), Intermediate LS (12-13 piglets) and Large LS (14-19piglets). Gilts were also separated in three classes according to their birth weight: Low BW (530-1200 g), IntermediateBW (1205-1600 g) and High BW (1605-2535 g). When compared to High BW gilts, the risk of death until weaning wasgreater (P 0.05). The risk of not being selected forbreeding was greater (P < 0.09) in Light BW gilts than in High BW gilts in all litter size classes. Low BW gilts were olderat the beginning...

Environmental effects on reproductive traits in Santa Ines sheep / Efeitos ambientais sobre características reprodutivas em ovinos Santa Inês

In this research we aimed to study environmental effects about litter size and weaning rate in Santa Ines sheep by means of generalized linear models. We used the data from experimental sheep herd of Santa Ines, of the Federal University of Piaui, Campus Professora Cinobelina Elvas, in Bom Jesus-PI, during 2008-2010. The environmental effects studied were: mating year, mating station, birth season, birth type, offspring sex, ewe age at birth, ewe weight at birth and birth weight as covariate. For statistical analysis we used the GENMOD procedure contained in SAS. Mean values for litter size and weaning rates were 1.36 and 68.18% respectively. The effect of ewe weight was significant about the litter size. There was no significant effect of birth season on the weaning rate. Correlations between productive and reproductive traits ranged from negative to positive low magnitude. The effects of ewe weight at birth and birth weight were important sources of variation for litter size and weaning rates, which reflects the need to consider these effects in models of genetic and phenotypic evaluation.(AU)

O objetivo com esta pesquisa foi estudar efeitos ambientais sobre a prolificidade e a taxa de desmame em ovinos Santa Inês, por meio de modelos lineares generalizados. Foram utilizados dados do rebanho experimental de ovinos da raça Santa Inês, da Universidade Federal do Piauí, Campus Universitário Professora Cinobelina Elvas, em Bom Jesus-PI, no período de 2008 a 2010. Os efeitos ambientais estudados foram: ano de cobertura, Período de cobertura, Período de nascimento, tipo de nascimento, sexo da cria, idade da mãe ao parto, peso da mãe ao parto e peso ao nascer como covariável. Para análise estatística foi utilizado o procedimento GENMOD contido no programa SAS. Os valores médios de prolificidade e taxa de desmame foram respectivamente 1,36 e 68,18%. O efeito do peso da mãe ao parto foi significativo sobre a prolificidade. Observou-se efeito significativo de Período de nascimento sobre a taxa de desmame. As correlações entre características produtivas e reprodutivas variaram de negativas a positivas de baixa magnitude. Os efeitos de peso da mãe ao parto e peso ao nascer mostraram-se importantes fontes de variação para prolificidade e taxa de desmame, o que reflete a necessidade de considerar estes efeitos em modelos de avaliação genética e fenotípica.(AU)

Efeito do flushing sobre o desempenho reprodutivo de ovelhas Morada Nova e Santa Inês submetidas à inseminação artificial em tempo fixo / The effect of flushing on the reproductive performance of Morada Nova and Santa Inês ewes submitted to fixed time artificial insemination

O objetivo do estudo foi analisar o efeito do flushing, do protocolo hormonal para sincronização de estro e da IATF sobre o desempenho reprodutivo de ovelhas Morada Nova (MN) e Santa Inês (SI). Foram utilizadas 27 ovelhas SI e 24 ovelhas MN suplementadas com concentrado (1% do peso vivo, em média) durante 75 dias de estação reprodutiva. Após 30 dias de suplementação, as ovelhas foram sincronizadas com protocolo hormonal (PH) à base de progestágeno, eCG e cloprostenol. A observação de estro foi realizada após 12, 24, 36 e 48 horas do término do PH, com o auxílio de dois rufiões, e a IATF foi realizada aproximadamente 55 horas após o final do PH. Do 20º ao 45º dia após o início do PH, realizou-se o repasse com um reproduto Dorper. O diagnóstico de prenhez foi realizado 70 dias após a IATF. Foi analisado o peso, escore da condição corporal (ECC), taxa de apresentação de estro, taxa de prenhez e prolificidade, testando-se os efeitos da raça, semana de suplementação (SS) e classe de ECC. O peso e ECC das ovelhas variaram em função da SS. Foi observada taxa de estro de 88,2%, sendo que 43,2% das ovelhas apresentaram estro até 24 horas do final do PH. A taxa de prenhez por IATF foi de 31,4% e a de prenhez após repasse foi de 50,0%, sendo que a classe de ECC interferiu nas taxas de prenhez. Obteve-se maior porcentagem de partos múltiplos de ovelhas prenhes por IATF do que por monta natural no repasse. Conclui-se que o flushing resultou em ganho de peso e aumento do ECC, o que garantiu a padronização do rebanho para a estação reprodutiva e, consequentemente, melhorou o desempenho reprodutivo. O PH utilizado aumentou a prolificidade e adiantou o início do estro; porém, não foi eficiente na sincronização de ovelhas deslanadas.(AU)

The aim of this study was to analyze the effect of flushing on the reproductive performance of Morada Nova (MN) and Santa Inês (SI) ewes submitted to fixed time artificial insemination (TAI). Twenty seven SI and 24 MN supplemented with concentrate (1% of live weight, on average), for 75 days during the breeding season. After 30 days of supplementation, ewes were synchronized with the aid of a hormonal protocol (HP) based on progesterone, eCG and cloprostenol. The estrus observation was conducted at 12, 24, 36 and 48 h after the end of HP with the aid of two ruffians. TAI was done 55 h after the end of HP. From 20 to 45 days after the beginning of the HP ewes were exposed to rams (natural breeding). The pregnancy diagnosis was evaluated 70 days after TAI. We analyzed the weight, body condition score, estrus rate, pregnancy rate and prolificacy testing the effects of race, week of supplementation and body condition score class. The weight and body conditions of ewes varied according to the week of supplementation, with higher values in the first two weeks following TAI. The estrus rate was 88.2% and 43.2% of the ewes showed estrus up to 24 hours of the end of the HP. The pregnancy rate per TAI was 31.3% and the pregnancy rate after natural breeding was 50.0%. It was observed that body condition score classes interfered in pregnancy rates. There was a higher percentage of multiple births by pregnancy by TAI than by natural breeding. It was concluded that the flushing resulted in weight gain and better body conditions ensuring the standardization of the herd for breeding season, which therefore improved reproductive performance. The HP used advanced the onset of estrus and increased prolificacy, but was inefficient in the synchronization of woolless sheep.(AU)

Efeitos ambientais sobre características reprodutivas em ovinos Santa Inês

In this research we aimed to study environmental effects about litter size and weaning rate in Santa Ines sheep by means of generalized linear models. We used the data from experimental sheep herd of Santa Ines, of the Federal University of Piaui, Campus Professora Cinobelina Elvas, in Bom Jesus-PI, during 2008-2010. The environmental effects studied were: mating year, mating station, birth season, birth type, offspring sex, ewe age at birth, ewe weight at birth and birth weight as covariate. For statistical analysis we used the GENMOD procedure contained in SAS. Mean values for litter size and weaning rates were 1.36 and 68.18% respectively. The effect of ewe weight was significant about the litter size. There was no significant effect of birth season on the weaning rate. Correlations between productive and reproductive traits ranged from negative to positive low magnitude. The effects of ewe weight at birth and birth weight were important sources of variation for litter size and weaning rates, which reflects the need to consider these effects in models of genetic and phenotypic evaluation.

O objetivo com esta pesquisa foi estudar efeitos ambientais sobre a prolificidade e a taxa de desmame em ovinos Santa Inês, por meio de modelos lineares generalizados. Foram utilizados dados do rebanho experimental de ovinos da raça Santa Inês, da Universidade Federal do Piauí, Campus Universitário Professora Cinobelina Elvas, em Bom Jesus-PI, no período de 2008 a 2010. Os efeitos ambientais estudados foram: ano de cobertura, Período de cobertura, Período de nascimento, tipo de nascimento, sexo da cria, idade da mãe ao parto, peso da mãe ao parto e peso ao nascer como covariável. Para análise estatística foi utilizado o procedimento GENMOD contido no programa SAS. Os valores médios de prolificidade e taxa de desmame foram respectivamente 1,36 e 68,18%. O efeito do peso da mãe ao parto foi significativo sobre a prolificidade. Observou-se efeito significativo de Período de nascimento sobre a taxa de desmame. As correlações entre características produtivas e reprodutivas variaram de negativas a positivas de baixa magnitude. Os efeitos de peso da mãe ao parto e peso ao nascer mostraram-se importantes fontes de variação para prolificidade e taxa de desmame, o que reflete a necessidade de considerar estes efeitos em modelos de avaliação genética e fenotípica.

Environmental effects on reproductive traits in Santa Ines sheep / Efeitos ambientais sobre características reprodutivas em ovinos Santa Inês

In this research we aimed to study environmental effects about litter size and weaning rate in Santa Ines sheep by means of generalized linear models. We used the data from experimental sheep herd of Santa Ines, of the Federal University of Piaui, Campus Professora Cinobelina Elvas, in Bom Jesus-PI, during 2008-2010. The environmental effects studied were: mating year, mating station, birth season, birth type, offspring sex, ewe age at birth, ewe weight at birth and birth weight as covariate. For statistical analysis we used the GENMOD procedure contained in SAS. Mean values for litter size and weaning rates were 1.36 and 68.18% respectively. The effect of ewe weight was significant about the litter size. There was no significant effect of birth season on the weaning rate. Correlations between productive and reproductive traits ranged from negative to positive low magnitude. The effects of ewe weight at birth and birth weight were important sources of variation for litter size and weaning rates, which reflects the need to consider these effects in models of genetic and phenotypic evaluation.

O objetivo com esta pesquisa foi estudar efeitos ambientais sobre a prolificidade e a taxa de desmame em ovinos Santa Inês, por meio de modelos lineares generalizados. Foram utilizados dados do rebanho experimental de ovinos da raça Santa Inês, da Universidade Federal do Piauí, Campus Universitário Professora Cinobelina Elvas, em Bom Jesus-PI, no período de 2008 a 2010. Os efeitos ambientais estudados foram: ano de cobertura, Período de cobertura, Período de nascimento, tipo de nascimento, sexo da cria, idade da mãe ao parto, peso da mãe ao parto e peso ao nascer como covariável. Para análise estatística foi utilizado o procedimento GENMOD contido no programa SAS. Os valores médios de prolificidade e taxa de desmame foram respectivamente 1,36 e 68,18%. O efeito do peso da mãe ao parto foi significativo sobre a prolificidade. Observou-se efeito significativo de Período de nascimento sobre a taxa de desmame. As correlações entre características produtivas e reprodutivas variaram de negativas a positivas de baixa magnitude. Os efeitos de peso da mãe ao parto e peso ao nascer mostraram-se importantes fontes de variação para prolificidade e taxa de desmame, o que reflete a necessidade de considerar estes efeitos em modelos de avaliação genética e fenotípica.

Reproductive biology of the coypu, Myocastor coypus (Rodentia: Myocastoridae) in western Japan

We describe the reproductive biology of the coypu, Myocastor coypus (Molina, 1782), in western Japan, as an attempt to contribute to an efficient population control program of the coypu population. A total of 212 specimens (113 males and 99 females) were collected in the Tottori prefecture from February 2010 to January 2012. From the age estimation based on body weight and molar eruption pattern, we determined that both males and females reach sexual maturity at 4-6 months of age. Of the 72 mature females examined, 60 (83.3%) were pregnant, with a mean litter size of 6.5 ± 2.4 (mean ± SE). The onset of sexual maturity in the western Japanese population was relatively earlier when compared with indigenous and other introduced populations. Furthermore, the population in Japan had relatively higher pregnancy rates and larger litter sizes, without obvious seasonal fluctuation. These observations may imply that the hunting pressure in Japan in the past 50 years has been strong enough to select individuals that mature earlier; however, nothing in the present habitat of the coypu population seems to be limiting reproduction. The relatively high reproductive potential of the present population in the mild climate of western Japan must be considered when determining appropriate management measures for this species.

Reproductive biology of the coypu, Myocastor coypus (Rodentia: Myocastoridae) in western Japan

We describe the reproductive biology of the coypu, Myocastor coypus (Molina, 1782), in western Japan, as an attempt to contribute to an efficient population control program of the coypu population. A total of 212 specimens (113 males and 99 females) were collected in the Tottori prefecture from February 2010 to January 2012. From the age estimation based on body weight and molar eruption pattern, we determined that both males and females reach sexual maturity at 4-6 months of age. Of the 72 mature females examined, 60 (83.3%) were pregnant, with a mean litter size of 6.5 ± 2.4 (mean ± SE). The onset of sexual maturity in the western Japanese population was relatively earlier when compared with indigenous and other introduced populations. Furthermore, the population in Japan had relatively higher pregnancy rates and larger litter sizes, without obvious seasonal fluctuation. These observations may imply that the hunting pressure in Japan in the past 50 years has been strong enough to select individuals that mature earlier; however, nothing in the present habitat of the coypu population seems to be limiting reproduction. The relatively high reproductive potential of the present population in the mild climate of western Japan must be considered when determining appropriate management measures for this species.