Genetic relationship between purebred and crossbred sow longevity

Background The overall breeding objective for a nucleus swine selection program is to improve crossbred commercial performance. Most genetic improvement programs are based on an assumed high degree of positive relationship between purebred performance in a nucleus herd and their relatives’ crossbred performance in a commercial herd. The objective of this study was to examine the relationship between purebred and crossbred sow longevity performance. Sow longevity was defined as a binary trait with a success occurring if a sow remained in the herd for a certain number of parities and including the cumulative number born alive as a measure of reproductive success. Heritabilities, genetic correlations, and phenotypic correlations were estimated using THRGIBBS1F90. Results Results indicated little to no genetic correlations between crossbred and purebred reproductive traits. This indicates that selection for longevity or lifetime performance at the nucleus level may not result in improved longevity and lifetime performance at the crossbred level. Early parity performance was highly correlated with lifetime performance indicating that an indicator trait at an early parity could be used to predict lifetime performance. This would allow a sow to have her own record for the selection trait before she has been removed from the herd. Conclusions Results from this study aid in quantifying the relationship between purebred and crossbred performance and provide information for genetic companies to consider when developing a selection program where the objective is to improve crossbred sow performance. Utilizing crossbred records in a selection program would be the best way to improve crossbred sow productivity

Heritability of longevity in Large White and Landrace sows using continuous time and grouped data models

<p>Abstract</p> <p>Background</p> <p>Using conventional measurements of lifetime, it is not possible to differentiate between productive and non-productive days during a sow's lifetime and this can lead to estimated breeding values favoring less productive animals. By rescaling the time axis from continuous to several discrete classes, grouped survival data (discrete survival time) models can be used instead.</p> <p>Methods</p> <p>The productive life length of 12319 Large White and 9833 Landrace sows was analyzed with continuous scale and grouped data models. Random effect of herd*year, fixed effects of interaction between parity and relative number of piglets, age at first farrowing and annual herd size change were included in the analysis. The genetic component was estimated from sire, sire-maternal grandsire, sire-dam, sire-maternal grandsire and animal models, and the heritabilities computed for each model type in both breeds.</p> <p>Results</p> <p>If age at first farrowing was under 43 weeks or above 60 weeks, the risk of culling sows increased. An interaction between parity and relative litter size was observed, expressed by limited culling during first parity and severe risk increase of culling sows having small litters later in life. In the Landrace breed, heritabilities ranged between 0.05 and 0.08 (s.e. 0.014-0.020) for the continuous and between 0.07 and 0.11 (s.e. 0.016-0.023) for the grouped data models, and in the Large White breed, they ranged between 0.08 and 0.14 (s.e. 0.012-0.026) for the continuous and between 0.08 and 0.13 (s.e. 0.012-0.025) for the grouped data models.</p> <p>Conclusions</p> <p>Heritabilities for length of productive life were similar with continuous time and grouped data models in both breeds. Based on these results and because grouped data models better reflect the economical needs in meat animals, we conclude that grouped data models are more appropriate in pig.</p

Whole-genome SNP association analysis of reproduction traits in the Finnish Landrace pig breed

<p>Abstract</p> <p>Background</p> <p>Good genetic progress for pig reproduction traits has been achieved using a quantitative genetics-based multi-trait BLUP evaluation system. At present, whole-genome single nucleotide polymorphisms (SNP) panels provide a new tool for pig selection. The purpose of this study was to identify SNP associated with reproduction traits in the Finnish Landrace pig breed using the Illumina PorcineSNP60 BeadChip.</p> <p>Methods</p> <p>Association of each SNP with different traits was tested with a weighted linear model, using SNP genotype as a covariate and animal as a random variable. Deregressed estimated breeding values of the progeny tested boars were used as the dependent variable and weights were based on their reliabilities. Statistical significance of the associations was based on Bonferroni-corrected <it>P</it>-values.</p> <p>Results</p> <p>Deregressed estimated breeding values were available for 328 genotyped boars. Of the 62 163 SNP in the chip, 57 868 SNP had a call rate > 0.9 and 7 632 SNP were monomorphic. Statistically significant results (<it>P</it>-value < 2.0E-06) were obtained for total number of piglets born in first and later parities and piglet mortality between birth and weaning in later parity, and suggestive associations (<it>P</it>-value < 4.0E-06) for piglet mortality between birth and weaning in first parity, number of stillborn piglets in later parity, first farrowing interval and second farrowing interval. Two of the statistically significant regions for total number of piglets born in first and later parities are located on chromosome 9 around 95 and 79 Mb. The estimated SNP effect in these regions was approximately one piglet between the two homozygote classes. By combining the two most significant SNP in these regions, favourable double homozygote animals are expected to have 1.3 piglets (<it>P</it>-value = 1.69E-08) more than unfavourable double homozygote animals. A region on chromosome 9 (66 Mb) was statistically significant for piglet mortality between birth and weaning in later parity (0.44 piglets between homozygotes, <it>P</it>-value = 6.94E-08).</p> <p>Conclusions</p> <p>Three separate regions on chromosome 9 gave significant results for litter size and pig mortality. The frequencies of favourable alleles of the significant SNP are moderate in the Finnish Landrace population and these SNP are thus valuable candidates for possible marker-assisted selection.</p

Regional perinatal mortality differences in the Netherlands; care is the question

Background. Perinatal mortality is an important indicator of health. European comparisons of perinatal mortality show an unfavourable position for the Netherlands. Our objective was to study regional variation in perinatal mortality within the Netherlands and to identify possible explanatory factors for the found differences. Methods. Our study population comprised of all singleton births (904,003) derived from the Netherlands Perinatal Registry for the period 2000-2004. Perinatal mortality including stillbirth from 22+0weeks gestation and early neonatal death (0-6 days) was our main outcome measure. Differences in perinatal mortality were calculated between 4 distinct geographical regions North-East-South-West. We tried to explain regional differences by adjustment for the demographic factors maternal age, parity and ethnicity and by socio-economic status and urbanisation degree using logistic modelling. In addition, regional differences in mode of delivery and risk selection were analysed as health care factors. Finally, perinatal mortality was analysed among five distinct clinical risk groups based on the mediating risk factors gestational age and congenital anomalies. Results. Overall perinatal mortality was 10.1 per 1,000 total births over the period 2000-2004. Perinatal mortality was elevated in the northern region (11.2 per 1,000 total births). Perinatal mortality in the eastern, western and southern region was 10.2, 10.1 and 9.6 per 1,000 total births respectively. Adjustment for demographic factors increased the perinatal mortality risk in the northern region (odds ratio 1.20, 95% CI 1.12-1.28, compared to reference western region), subsequent adjustment for socio-economic status and urbanisation explained a small part of the elevated risk (odds ratio 1.11, 95% CI 1.03-1.20). Risk group analysis showed that regional differences were absent among very preterm births (22+0- 25+6weeks gestation) and most prominent among births from 32+0gestation weeks onwards and among children with severe congenital anomalies. Among term births (37+0weeks) regional mortality differences were largest for births in women transferred from low to high risk during delivery. Conclusion. Regional differences in perinatal mortality exist in the Netherlands. These differences could not be explained by demographic or socio-economic factors, however clinical risk group analysis showed indications for a role of health care factors

Prochloraz tolerance of Pyrenophora teres population in Finland

Barley leaves infected with Pyrenophora teres Drechs. f. teres were collected from farmers fields and an experimental field for evaluation of efficacy of fungicides at MTT Agrifood Research Finland (MTT), in 2003. The aim was to test the efficacy of prochloraz to inhibit in vitro growth of P. teres. Potato dextrose agar (PDA) dishes amended with 0.1 and 1.0 ìg ml-1 prochloraz were used for testing 364 isolates of P. teres based on prelimenary experiment. Isolates from MTTs experimental field were growing slower on fungicide- amended media than isolates from farmers fields. The overall mean inhibition of radial growth was 63 and 86% on media amended with 0.1 and on 1.0 ìg ml-1 prochloraz, respectively. Isolates of different origin differed significantly on growth on fungicide-amended media. The isolates capable of growing on increased concentrations of prochloraz were most commonly isolated from fields, where prochloraz was sprayed during the growing season. Within MTTs experimental field no effect of fungicide application during the growing season was observed on growth of isolates in vitro. Data from this survey was insufficient for making further conclusions regarding the effect of agricultural practices on selection of fungicide tolerant P. teres isolates. Fungicides with different types of mode of action are recommended for use together with prochloraz against the net blotch pathogen in Finland. These results are preliminary.;Ohranverkkolaikku on tärkein taudinaiheuttaja suomalaisessaohranviljelyssä, ja se aiheuttaa aroilla ohralajikkeilla keskimäärin 40 % tautisuuden ja merkittäviä satotappioita. Tautia torjutaan siemenpeittauksella tai kasvustoruiskutuksilla kasvukauden aikana. Prokloratsi (kauppavalmisteet Sportak ja Predule) on yleinen ohran kasvinsuojeluaine. Suomessa myydyistä peittausaineista puolet sisältää vaikuttavana aineena joko prokloratsia tai imatsaliilia tai näiden yhdistelmiä. Molemmat aineet kuuluvat samaan kemialliseen ryhmään ja vaikuttavat samalla tavalla. Tämän tutkimuksen tarkoituksena oli selvittää prokloratsia kestävien ohranverkkolaikkua aiheuttavien tautikantojen esiintymistä lounaishämäläisillä pelloilla. Näytteitä kerättiin yhteensä 364 kpl vuonna 2003 kolmelta viljelijän pellolta ja yhdeltä MTT:n (Maa- ja elintarviketalouden tutkimuskeskus) koealalta. Viljelijöiden pelloilta kerätyt tautikannat, jotka olivat saaneet Sportak-käsittelyn kasvukauden aikana, kasvoivat laboratoriotesteissä paremmin kasvitautiainetta sisältävillä kasvatusmaljoilla kuin koealalta kerätyt tautikannat. Viljelijöiden pelloilta peräisin olevat tautikannat kasvoivat parhaiten sekä laimeammalla että vahvemmalla testialustalla verrattuna tautikantoihin, joilla oli käytetty muita kasvinsuojeluaineita. Vastaavaa testiä ei ole tehty aiemmin, joten ei voida osoittaa tautiaineen kestävyyden muuttuneen. Tulokset osoittavat, että tautikantojen kasvinsuojeluaineen kestävyys voi vaihdella eri pelloilla. Tämä alustava aineisto oli kuitenkin riittämätön yleistettävien johtopäätösten tekoon. Aineiden tehoa kannattaa seurata. Suositeltavinta olisi käyttää aineseoksia ohranverkkolaikun torjunnassa ja välttää samalla tavalla vaikuttavien kemiallisten kasvinsuojeluaineiden pitkäaikaista käyttöä samalla peltolohkolla. Tautiaineiden tehon turvaamiseksi tautia pitäisi pyrkiä vähentämään myös muilla keinoilla, kuten viljelykierrolla, kasvijätteiden muokkauksella ja taudinkestävien ohralajikkeiden viljelyllä. Tämä alustava tutkimus osoitti, että ohranverkkolaikun aiheuttajan prokloratsin kestävyydessä on eroa peltojen välillä

Prochloraz tolerance of Pyrenophora teres population in Finland

Barley leaves infected with Pyrenophora teres Drechs. f. teres were collected from farmers fields and an experimental field for evaluation of efficacy of fungicides at MTT Agrifood Research Finland (MTT), in 2003. The aim was to test the efficacy of prochloraz to inhibit in vitro growth of P. teres. Potato dextrose agar (PDA) dishes amended with 0.1 and 1.0 ìg ml-1 prochloraz were used for testing 364 isolates of P. teres based on prelimenary experiment. Isolates from MTTs experimental field were growing slower on fungicide- amended media than isolates from farmers fields. The overall mean inhibition of radial growth was 63 and 86% on media amended with 0.1 and on 1.0 ìg ml-1 prochloraz, respectively. Isolates of different origin differed significantly on growth on fungicide-amended media. The isolates capable of growing on increased concentrations of prochloraz were most commonly isolated from fields, where prochloraz was sprayed during the growing season. Within MTTs experimental field no effect of fungicide application during the growing season was observed on growth of isolates in vitro. Data from this survey was insufficient for making further conclusions regarding the effect of agricultural practices on selection of fungicide tolerant P. teres isolates. Fungicides with different types of mode of action are recommended for use together with prochloraz against the net blotch pathogen in Finland. These results are preliminary.