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TRP1 Peptide Requires Internalization and is Partially Dependent on GILT for Efficient Presentation on MHC Class IISjursen, Anne Marie 01 May 2012 (has links)
A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Tyrosinase-related protein 1 (TRP1) is a melanosomal integral membrane protein and melanocyte differentiation antigen that contributes to the synthesis of melanin in melanocytes. Present in both benign and malignant melanocytes, it has been implicated in the autoimmune development of vitiligo and melanoma antitumor immunity. Since a naturally occurring MHC class II-restricted TRP1 epitope contains cysteine residues, we hypothesized that this epitope will require internalization and reduction by gamma-interferon-inducible lysosomal thiol reductase (GILT) for presentation on class II. GILT is known to catalyze the reduction of protein disulfide bonds in the endocytic pathway and contribute to antigen processing and presentation of certain MHC class I and class II epitopes. We have previously shown that GILT is required for efficient class II-restricted presentation of TRP1. Here, we found that TRP1 peptide presentation is partially dependent on GILT and that TRP1 peptide requires internalization for efficient presentation on class II. We also determined that antigen presentation increased with increasing peptide dose and increasing APC:T cell ratio. Compared to other TRP1-specific T cells, primary TRP1-specific T cells from TRP1BwRAG-/-
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TRP1tg mice produce maximal IL-2 in response to presentation of TRP1. These results further illustrate the importance of GILT in the processing and presentation of TRP1. Thus, GILT may play a role in both the development of autoimmune vitiligo and anti-melanoma immune responses.
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Management and nutrition of the replacement gilt.Van Wettere, William January 2008 (has links)
Replacement gilts and early parity sows constitute a large, and increasing, proportion of modern breeding herds. Breeding herd profitability is therefore increasingly dependant on the efficiency of gilt management strategies as well as litter size at first farrowing; however, incidences of reproductive failures and small first litter sizes are common within cohorts of replacement gilts. Hence, this thesis had two primary aims which were addressed in four experiments; one, to identify whether the puberty stimulation and mating strategies developed for genotypes of 20 to 30 years ago are suitable for today’s heavier yet leaner genotypes; and two, to better understand the influence of pre-pubertal growth rate and metabolic status on reproductive maturation, puberty attainment and potential litter size. In experiment 1, 192 Large White/Landrace crossbred gilts were used to compare the effects on puberty attainment of commencing boar exposure at 161, 182 or 203 days of age, and the effect of first mating gilts at either the pubertal or second oestrus on ovulation rate and early embryo survival. Gilts were artificially inseminated at the allocated oestrus, with the reproductive tracts collected at 22.8 ± 0.4 days after first mating (mean ± S.E.M), and the numbers of corpora lutea and viable embryos recorded. Delaying first boar contact until 182 or 203 days of age significantly (P < 0.01) reduced days-to puberty and increased the proportion of gilts attaining puberty within 10 days of start of boar exposure. Gilt age at mating had no effect on potential litter size; however, there was a tendency for gilts mated at their second oestrus to shed 0.6 more ova, and possess one more embryo at day 20 of pregnancy. Experiment 2 determined the effects of long- (chronic) and short- (acute) term moderate dietary restriction on ovarian development and oocyte developmental competence in 161- and 175- day old, pre-pubertal gilts. Both chronic and acute periods of moderate feed restriction reduced the number of medium follicles present on the ovaries of 161- and 175-day old gilts, as well as the proportion of oocytes reaching Metaphase II in vitro. However, feeding level during the 14 days prior to ovary collection had the greatest effect on follicular growth and oocyte quality. Experiments 3 and 4 investigated the effects of the same dietary treatments on the timing of puberty attainment in response to boar exposure and potential litter size following mating at the pubertal oestrus. Chronic dietary restriction during the pre-pubertal period delayed puberty attainment, but the timing of the pubertal response was unaffected by acute, moderate dietary restriction of previously well-fed gilts during the period immediately prior to, and coincident with, boar exposure. Acute dietary restriction or repletion stimulated an increase or decrease, respectively, in pubertal ovulation rates; however, neither the number of viable embryo present on day 22 of gestation nor embryo survival were affected by the nutritional treatments used in these studies. Overall, these results demonstrate that the timing and synchrony of puberty attainment is significantly improved when gilts first receive boar exposure at 182 days of age (or older). It is, therefore, concluded that sexual maturity, as measured by responsiveness to boar contact, occurs later in modern genotypes. It is also evident that within the age range investigated, delaying first mating until the second oestrus does not significantly increase either ovulation rate or embryo number at day 20 post-mating. Further, the current data provide the first evidence that despite profoundly affecting the size and morphology of the antral follicle pool as well as pubertal ovulation rates, subtle alterations in dietary intake have no affect on the number or proportion of embryos surviving the pre-and peri-implantation period. It is evident the litter size of gilts mated at the pubertal oestrus is not determined by the number of ova shed, with the current data demonstrating that increasing ovulation rates results in increased embryo mortality. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339082 / Thesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 2008
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Effects of nursery floor space allowance on growth, physiology, and immunology of replacement giltsCallahan, Stuart Russell 16 October 2013 (has links)
In U.S. swine herds, sow removal rates due to death and voluntary and involuntary culling exceed 50% annually. This loss poses an economic problem for producers because the cost of acquiring replacement females is great. Although research has shown that crowding in the nursery has negative impacts on growth, research describing effects of crowding on subsequent reproductive performance and longevity in sows is lacking. This experiment was conducted to determine the impacts of crowding during the nursery phase of production on growth, physiology, and immunology in replacement gilts. Gilts (22.3 ± 3.2 d of age and 5.6 ± 0.6 kg BW) were subjected to floor space allocations of 0.15, 0.19, or 0.27 m2/pig during a 7-wk nursery period. Floor space allocations were achieved by altering the number of pigs per pen (14, 11, and 8 gilts/pen, respectively). As was expected, reduced floor space allowance in the nursery negatively affected growth performance although there was inconclusive physiological and immunological evidence to suggest that pigs were experiencing highly stressful conditions. Although feed intake was not measured, changes in blood counts and blood chemistry for gilts allowed reduced floor space were similar to other studies that reported negative effects of crowding on feed consumption. Further study of the gilts involved in this study will aim to determine if there are any links between the effects of crowding during the nursery and subsequent reproductive performance and longevity in the breeding herd. / Master of Science
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Effect of P.G. 600 on the timing of ovulation in gilts treated with Regu-mateHorsley, Brandon Ryan 28 September 2004 (has links)
We previously reported that ovulation rate, but not pregnancy rate or litter size at d 30 post-mating, was enhanced by gonadotropin treatment (P.G. 600; Intervet America Inc., Millsboro, DE) in gilts fed a progestin (Regu-mate; Intervet America Inc.) compared with gilts receiving progestin alone. We hypothesized that P.G. 600 altered the timing of ovulation, therefore mating gilts 12 and 24 h after first detection of estrus, as is common in the swine industry, may not have been the most appropriate breeding regimen. The objective of this study was to determine the effect of P.G. 600 on the timing of ovulation in gilts treated with Regu-mate. Randomly cycling, crossbred gilts (5.5 m of age, 117 kg BW, and 14.7 mm BF) were fed a diet containing Regu-mate to provide 15 mg/d for 18 d. Twenty-four h after Regu-mate withdrawal, gilts received i.m. P.G. 600 (n = 25) or saline (n = 25). Gilts were checked for estrus at 8 h intervals. After first detection of estrus, trans-rectal ultrasonography was performed at 8 h intervals to determine the time of ovulation. Gilts were killed 9 to 11 d after the onset of estrus to determine ovulation rate. All gilts displayed estrus by 7 d after treatment with P.G. 600 or saline. Compared with saline, P.G. 600 increased (P = 0.07) ovulation rate (14.8 + 1.1 vs. 17.5 + 1.0, respectively). The intervals from injection-to-estrus (98.4 + 2.7 vs. 110.9 + 2.7 h; P < 0.01) and injection-to-ovulation (128.6 + 2.8 vs. 141.9 + 3.2 h; P < 0.01) were decreased in gilts treated with P.G. 600 compared with gilts treated with saline. Estrus duration (54.4 + 2.3 vs. 53.7 + 2.5 h; P = 0.83), estrus-to-ovulation (30.2 + 2.0 vs. 31.7 + 2.2 h; P = 0.62) and time of ovulation as a percentage of duration of estrus (55.8 + 2.7 vs. 57.5 + 3.0%; P = 0.67) were similar for the P.G. 600 and saline-injected gilts, respectively. In summary, P.G. 600 advanced the onset of estrus and ovulation following termination of Regu-mate treatment and increased ovulation rate. However, treatment of gilts with P.G. 600 had no effect on the timing of ovulation relative to the onset of estrus. / Master of Science
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Effects of diet induced short chain fatty acids on blood metabolites and key regulators of lipid metabolism in giltsLattimer, James M. January 1900 (has links)
Doctor of Philosophy / Department of Human Nutrition / Mark D. Haub / Background: Dietary fiber has been shown to help improve several metabolic disorders including obesity and type II diabetes. However, the mechanism by which this occurs is poorly understood.
Purpose: This study was designed to compare the effects of energy restriction and dietary fiber and subsequent production of short chain fatty acids on body composition, biomarkers of health, and hepatic and myocellular expression of key regulators of lipid metabolism
Methods: Crossbred gilts (n=17) were randomly assigned to either a control (CON), high fiber (HF) or energy restricted (ER) diet for 42 days. Gilts on the CON and HF diets were fed ad libitum. The ER Gilts were pair fed HF gilts and matched for body weight gain. Blood samples were collected and glucose, insulin, triglycerides, non-esterified fatty acids and short chain fatty acids (SCFA) concentrations were measured. Liver and muscle tissue were biopsied and expression of peroxisome proliferator-activated receptor gama (PGC-1α) and carnitine palmitoyltransferase 1 (CPT1) were determined via RT-PCR.
Results: HF gilts had significantly higher plasma TG and lower NEFA concentrations when compared to the CON and ER. The HF diet elicited a significant increase in all plasma SCFA concentrations. No differences in fold change of myocyte CPT1 and PGC-1α mRNA expression were found while they tended to be lower in hepatic samples of the HF gilts. HF gilts also had a lower (P < 0.05) back fat thickness when compared to the ER even though energy intakes were similar. Minimal changes were observed in fasting glucose and insulin as a result of diet.
Conclusions: Gilts consuming a diet high in dietary fiber (DF) significantly altered their plasma lipid profiles independently to that of energy restriction and body weight and appears to be a result of plasma SCFA concentration. DF and/or SCFA appear to have minimal affects on CPT1 and PGC-1α in the liver and muscle of gilts.
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Estudo da relação morfométrica de útero e placenta com a capacidade uterina em leitoas / Morfometric relation between uterus and placentae with the uterine capacity giltsVianna, Wagner Loesch 19 February 2004 (has links)
Nos suínos a capacidade uterina influencia o tamanho de leitegada, podendo servir como parâmetro para seleção de animais com melhor desempenho reprodutivo. Evidências destacam que a profundidade da penetração da pipeta correlaciona-se positivamente com o tamanho do útero, servindo de ferramenta para métodos de seleção de leitoas com maior capacidade uterina. Sessenta e seis leitoas pré-púberes de linhagem comercial tiveram a puberdade induzida através de combinação hormonal (eCG e LH). A medida de comprimento da penetração da pipeta de IA foi realizada nas 40 leitoas que apresentaram o 2º cio de maneira sincronizada, sendo que 4 leitoas retornaram o cio. Aos 69 dias de gestação, em média, as 36 leitoas foram abatidas, analisando-se os dados de tamanho de útero, placenta e sobrevivência fetal. O comprimento e peso uterino apresentaram uma correlação positiva significativa com a taxa de sobrevivência gestacional (r=0,43 e r=0,37, respectivamente). Verificou-se que a penetração da pipeta no animal não foi capaz de predizer a capacidade uterina, embora o tamanho uterino tenha influenciado positivamente a taxa de sobrevivência gestacional. A área da placenta correlacionou-se positivamente com o peso da placenta (r=0,66; P<0,0001), e estas com o peso fetal (r=0,60; P<0,0001 e r=0,59; P<0,001, respectivamente). O número de fetos, o comprimento uterino e o peso uterino não se associaram com peso fetal. Fundamentando-se nos resultados obtidos, a penetração da pipeta no momento da inseminação artificial não foi capaz de predizer a capacidade uterina, tampouco sobrevivência dos conceptos aos 70 dias de gestação. / Swines uterine capacity affects litter size, and it could be used as selection parameter of animals with a high reproductive performance. Evidences show that the catheter penetration length is positively correlated with uterine size, and it can be used as selection tool of high uterine capacity in gilts. Sixty six prepubertal gilts of commercial line had the puberty inducted by a hormonal combination (eCG and LH). The Artificial Insemination (AI) catheter penetration length was tested on fourty gilts at the second estrus, but four gilts returned to estrus. The thirty-six remained gilts were slaughtered an average at age sixty-nine of gestation, analyzing the uterus and placental size, and the concepts survival. The uterine length and weight showed a significative and positive correlation with the concepts survival rate (r=0,43 and r=0,37, respectively). The catheter penetration length was not able to predict the uterine capacity, however the uterine size had positively influentied the survival rate. The average of placental area was positively correlated with the average placental weight (r=0,66; P<0,0001), and those ones with the average fetal weight (r=0,60; P<0,0001 and r=0,59; P<0,001, respectively). Analyzing the results obtained, the catheter penetration length measurement during artificial insemination did not predict the uterine capacity, neither the concepts survival on seventy days of gestation age.
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Estudo da relação morfométrica de útero e placenta com a capacidade uterina em leitoas / Morfometric relation between uterus and placentae with the uterine capacity giltsWagner Loesch Vianna 19 February 2004 (has links)
Nos suínos a capacidade uterina influencia o tamanho de leitegada, podendo servir como parâmetro para seleção de animais com melhor desempenho reprodutivo. Evidências destacam que a profundidade da penetração da pipeta correlaciona-se positivamente com o tamanho do útero, servindo de ferramenta para métodos de seleção de leitoas com maior capacidade uterina. Sessenta e seis leitoas pré-púberes de linhagem comercial tiveram a puberdade induzida através de combinação hormonal (eCG e LH). A medida de comprimento da penetração da pipeta de IA foi realizada nas 40 leitoas que apresentaram o 2º cio de maneira sincronizada, sendo que 4 leitoas retornaram o cio. Aos 69 dias de gestação, em média, as 36 leitoas foram abatidas, analisando-se os dados de tamanho de útero, placenta e sobrevivência fetal. O comprimento e peso uterino apresentaram uma correlação positiva significativa com a taxa de sobrevivência gestacional (r=0,43 e r=0,37, respectivamente). Verificou-se que a penetração da pipeta no animal não foi capaz de predizer a capacidade uterina, embora o tamanho uterino tenha influenciado positivamente a taxa de sobrevivência gestacional. A área da placenta correlacionou-se positivamente com o peso da placenta (r=0,66; P<0,0001), e estas com o peso fetal (r=0,60; P<0,0001 e r=0,59; P<0,001, respectivamente). O número de fetos, o comprimento uterino e o peso uterino não se associaram com peso fetal. Fundamentando-se nos resultados obtidos, a penetração da pipeta no momento da inseminação artificial não foi capaz de predizer a capacidade uterina, tampouco sobrevivência dos conceptos aos 70 dias de gestação. / Swines uterine capacity affects litter size, and it could be used as selection parameter of animals with a high reproductive performance. Evidences show that the catheter penetration length is positively correlated with uterine size, and it can be used as selection tool of high uterine capacity in gilts. Sixty six prepubertal gilts of commercial line had the puberty inducted by a hormonal combination (eCG and LH). The Artificial Insemination (AI) catheter penetration length was tested on fourty gilts at the second estrus, but four gilts returned to estrus. The thirty-six remained gilts were slaughtered an average at age sixty-nine of gestation, analyzing the uterus and placental size, and the concepts survival. The uterine length and weight showed a significative and positive correlation with the concepts survival rate (r=0,43 and r=0,37, respectively). The catheter penetration length was not able to predict the uterine capacity, however the uterine size had positively influentied the survival rate. The average of placental area was positively correlated with the average placental weight (r=0,66; P<0,0001), and those ones with the average fetal weight (r=0,60; P<0,0001 and r=0,59; P<0,001, respectively). Analyzing the results obtained, the catheter penetration length measurement during artificial insemination did not predict the uterine capacity, neither the concepts survival on seventy days of gestation age.
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Caracterização do perfil sorológico de nulíparas suínas e da progênie, frente ao parvovírus suíno / Serological characterization of gilts and progeny, under Porcine ParvovirusGava, Danielle January 2012 (has links)
O parvovírus suíno (PPV) apresenta grande importância, principalmente em fêmeas nãoimunes, por causar perdas reprodutivas significativas. O primeiro trabalho foi desenvolvido sobre forma de revisão, e serviu como base para realização dos estudos seguintes. O segundo trabalho foi conduzido para determinar a resposta de anticorpos para PPV em 127 leitoas após a vacinação, avaliar a transferência de imunidade passiva e estimar a queda de anticorpos colostrais para PPV na leitegada. Foi realizada coleta de sangue nas leitoas em: (A) antes da primeira vacinação para PPV, (B) após a segunda dose; (C) no parto e (D) durante a segunda gestação. Além disto, colostro também foi coletado (E). Três leitões de cada fêmea foram selecionados e amostras de sangue foram coletadas: antes de mamar o colostro, 7, 21, 57, 87 e 128 dias de idade, a fim de verificar o declínio da imunidade passiva e estimar a meia-vida de anticorpos para PPV. O número de fetos mumificados, natimortos, nascidos vivos e nascidos totais do primeiro e segundo parto foram analizados. Os anticorpos para PPV foram testados por inibição da hemaglutinação (HI) e enzymelinked immunosorbent assay (ELISA), a fim de verificar a concordância entre estes dois métodos. A possível associação entre os títulos de anticorpos das fêmeas e dos leitões no soro e no colostro com os dados reprodutivos também foi investigada. A maioria das fêmeas (85,83%) tiveram anticorpos para PPV antes da vacinação, mas depois da vacina, todas as fêmeas soroconverteram. Aos sete dias de idade a maioria dos leitões apresentaram anticorpos para PPV e em torno dos 57 dias de idade somente 35,29% dos leitões eram positivos, alcançando a nulidade de anticorpos para PPV aos 87 dias de idade. A meia-vida estimada dos anticorpos colostrais foi 29,80 dias. A correlação entre o soro dos leitões e da fêmea no momento do parto foi r=0,77 (P<0,001) e com o colostro o valor de r foi 0,72 (P<0.001). A concordância entre os testes de ELISA e HI foi moderada (Spearman’s ρ= 0,89 e R2= 0.67). Houve diferença somente no número de mumificados entre o primeiro e segundo parto (P<0,001). O terceiro trabalho objetivou avaliar o perfil de anticorpos para PPV em diferentes sistemas de reposição de leitoas, correlacionando com dados reprodutivos. Cento e cinquenta 11 nulíparas com duas doses de vacina para PPV foram selecionadas de três sistemas de reposição diferentes: quarto sítio - A (n=36), granja receptora do quarto sítio - B (n=57) e granja multiplicadora - C (n=57). Os anticorpos para PPV foram medidos utilizando um teste de ELISA. Houve diferença entre as três granjas com relação ao título de anticorpos (P<0,05). Ao comparar os dados reprodutivos entre as granjas, houve diferença entre elas no número de nascidos totais e nascidos vivos, mas não foi observada diferença no percentual de natimortos e de mumificados (P>0,05). A correta preparação da leitoa, objetivando a proteção no momento da cobertura é fundamental para alcançar bom desempenho reprodutivo, independente do sistema de reposição utilizado. / Porcine parvovirus (PPV) has a great importance because causes significantly reproductive losses, mainly in non-immune gilts. The first study was developmented as a review, and served as a basis to carry out the following studies. The second study was conducted to determine the antibody response for PPV of 127 gilts in field conditions after vaccination, to evaluate the transfer of passive immunity and to estimate the decay of acquired colostral antibodies to PPV in the littermate. Gilts were bled at: (A) before the first vaccination to PPV, (B) after the second dose; (C) at farrowing and (D) during the second pregnancy. Added to these, colostrum was also collected (E). Three piglets of each gilt were selected and blood samples were collected: prior to initial colostrum intake, 7, 21, 57, 87 and 128 day-old, in order to verify the decrease of passive immunity and estimate the half-life of PPV antibodies. The number of mummified fetus, stillbirths, born alive and total born were analyzed from first and second parturition. The PPV antibodies were tested both with haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) in order to study the agreement between these methods. The possible association between gilts and piglets antibody titers in serum and colostrum with reproductive data was also investigated. Most gilts (85.83%) had antibodies to PPV before vaccination, but after vaccine, all gilts seroconverted. At 7 day-old most part of piglets had PPV antibodies and around 57 days-old only 35.29% of piglets were positive, reaching the PPV antibodies nullity at 87 days-old. The estimated average half-life of acquired colostral antibodies was 29.80 days. The correlation between piglets serum with gilt serum at farrowing time was r=0.77 (P<0.001) and with colostrum the r value was 0.72 (P<0.001). The agreement between ELISA and HI tests was moderate (Spearman’s ρ= 0.89 and R2= 0.67). The only difference between first and second parturition was observed on mummified fetuses (P<0.001). The objective of the third study was to evaluate the PPV antibodies profile in different gilts replacement systems, correlating with reproductive data. A hundred and fifty gilts with two doses of 13 PPV vaccine were selected from three different gilts replacement systems: Fourth site - A (n=36), fourth site receiver herd - B (n=57) and a farm producing dam lines - C (n=57). The PPV antibodies were measured by an ELISA test. There were a difference on antibody titers among the three herds (P<0.05). When we compared the reproductive data among herds, there were difference on total born and born alive, but this difference was not observed on the percentual of stillbirths and mummified (P>0.05). The correct gilt preparation, aiming the protection on mating time is fundamental to reach a great reproductive performance, independent of the replacement gilt system used.
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Modulation Of Disulfide-stabilized Structure Affects The Helper T-cell Response To Hiv/siv Gp120January 2014 (has links)
acase@tulane.edu
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Indução a puberdade em leitoas em diferentes idades e dois sistemas de manejo / Puberty induction in gilts at different ages and two management systemsRibeiro, Renato Rosa January 2015 (has links)
A antecipação da puberdade por meio da estimulação do macho poderá permitir que a primeira cobertura possa ser realizada mais cedo reduzindo assim os dias não produtivos de fêmeas suínas. No presente estudo, 417 fêmeas DB-DanBred foram estimuladas por 42 dias em dois tratamentos, BEAR, local específico de exposição das leitoas a diferentes machos, e BAIA, a exposição tradicional das leitoas na própria baia, em três idades diferentes de início de estímulo, 150, 170 e 200 dias. No sistema BEAR foram alojados quatro machos e as leitoas introduzidas nesta área permaneceram durante um período de 15 minutos, sendo os primeiros cinco minutos apenas em contato focinho com focinho e após um macho era solto na baia para uma estimulação por mais 10 minutos. No sistema BAIA o macho foi introduzido na baia de alojamento das fêmeas e tiveram 15 min de contato físico. Não houve diferença na porcentagem de entrada em estro em nenhum intervalo (10, 20, 30 e 45 dias) do início do estimulo e apresentação do estro quando comparados os dois sistemas, dentro de cada idade de início de estímulo. Porém a média do intervalo entre o início do estimulo e apresentação do estro foi significativamente menor quando o contato com o macho começou aos 200 dias em comparação com 150 e 170 dias de idade (14,6 ± 1,1 dias vs. 22,9 ± 1,4 e 20,0 ± 1,3 dias respectivamente, P <0,05). Da mesma forma, a proporção de fêmeas que atingiram a puberdade no período de 10 dias do início da exposição ao macho foi duas vezes maior em fêmeas que iniciaram o estímulo aos 200 dias de vida, quando comparadas com fêmeas que iniciaram os estímulos aos 150 e 170 dias. Em conclusão, os dados do presente estudo indicam que apesar da diferença de manejo de estimulação entre os sistemas BEAR e BAIA, não existe diferença na porcentagem de entrada em estro entre os dois sistemas. Além disso, é evidente que a sincronia da puberdade em fêmeas DB-DanBred é significativamente melhor quando a exposição ao macho é adiada para os 200 dias de idade. / The anticipation of puberty through stimulation of the boar can allow the first mating to be conducted earlier, thus reducing non-productive days of the female swine. In the present study, 417 DB-DanBred gilts were stimulated for 42 days in two treatments; BEAR, specific area of gilt exposure to different boars, and BAIA, traditional exposure of gilts in their own stall, at three different ages at the beginning of stimulation, 150, 170 and 200 days. In BEAR system four boars were housed and the gilts introduced in this area remained for 15 minutes, the first five minutes being just in snout to snout contact and then a boar was relaesed in the stall for stimulation for 10 more minutes. In BAIA system the boar was introduced in the lodging stall of the gilts and they had 15 minutes of physical contact. There was no difference in the estrus onset percentage at any interval (10, 20, 30 and 45 days) from the beginning of the stimulation and estrus presentation when comparing the two systems, within each age at the beginning of stimulation. However the average of the interval between the beginning of stimulation and presentation of estrus was significantly lower when the contact with the boar began at 200 days in comparison with 150 and 170 days of age (14.6 ± 1.1 days vs. 22.9 ± 1.4 and 20.0 ± 1.3 days respectively, P < 0.05). In the same way, the proportion of gilts that reached puberty within 10 days from the beginning of exposure to the boar was twice as high in gilts that began the stimulation at 200 days of age, when compared with gilts that began the stimulation at 150 and 170 days. In conclusion, the data of the present study indicate that, in spite of the stimulation management difference between BEAR and BAIA systems, a difference does not exist in the estrus onset percentage between the two systems. Furthermore, it is evident that timing of puberty in DB-DanBred gilts is significantly better when exposure to the boar is postponed to 200 days of age.
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