Breeding replacement gilts for organic pig herds

In this study, breeding structures and commercial sow lines were evaluated by economic and genetic simulation studies for their suitability to provide the Dutch organic pig sector with replacement gilts. Sow and litter performance from over 2000 crossbred sows from 2006 to 2007 were collected on 11 to 14 Dutch organic pig herds, respectively, and compared with conventional herds. Results showed that organic herds had lower farrowing rates (3.6% to 7.5%), more live born piglets per litter (0.4% to 1.2%) and higher preweaning mortality rates (7% to 13%) compared to conventional herds. These results were used to simulate economic performance of various combinations of breeding structures and sow lines under organic conditions, under the assumption of absence of genotype-environment interactions. Sow and litter performance data under organic conditions (total piglets born/litter, stillborn piglets/litter, mortality until weaning, lactation length, interval weaning-oestrus and sow culling rate) and the costprice calculation for the Dutch organic pig sector were used as input for the economic simulation studies. The expected genetic progress was simulated for three potential breeding structures of the organic sector: organic breeding herds producing F1 gilts (OrgBS), a flower breeding system (FlowerBS) and a two-line rotation breeding system (RotBS). In FlowerBS, an organic purebred sow line is bred, using on-farm gilt replacement. The OrgBS with a Yorkshire X Landrace cross had the highest margin per sow place ((sic)779), followed by RotBS with Yorkshire X Landrace cross ((sic)706) and FlowerBS with Yorkshire sow line ((sic)677). In case that an organic purebred sow population of 5000 sows would be available, FlowerBS gave the highest genetic progress in terms of cost price reduction ((sic)3.72/slaughter pig per generation), followed by RotBS and OrgBS ((sic)3.60/slaughter pig per generation). For FlowerBS, additional costs will be involved for maintaining a dedicated breeding programme. In conclusion, OrgBS using conventional genetics is economically the most viable option for the organic pig sector. However, this structure has clear disadvantages in terms of risks with regard to disease transmission and market demand. FlowerBS using a dedicated purebred organic line will only be cost-effective if sow population size is sufficiently large. RotBS might be a viable alternative, especially in combination with artificial insemination (AI) boars that are ranked according to an organic selection index. Regardless of breeding structure, the Yorkshire sow line gave the highest prolificacy and the highest economic returns on organic herds

Breeding replacement gilts for organic pig herds

In this study, breeding structures and commercial sow lines were evaluated by economic and genetic simulation studies for their suitability to provide the Dutch organic pig sector with replacement gilts. Sow and litter performance from over 2000 crossbred sows from 2006 to 2007 were collected on 11 to 14 Dutch organic pig herds, respectively, and compared with conventional herds. Results showed that organic herds had lower farrowing rates (3.6% to 7.5%), more live born piglets per litter (0.4% to 1.2%) and higher preweaning mortality rates (7% to 13%) compared to conventional herds. These results were used to simulate economic performance of various combinations of breeding structures and sow lines under organic conditions, under the assumption of absence of genotype-environment interactions. Sow and litter performance data under organic conditions (total piglets born/litter, stillborn piglets/litter, mortality until weaning, lactation length, interval weaning-oestrus and sow culling rate) and the costprice calculation for the Dutch organic pig sector were used as input for the economic simulation studies. The expected genetic progress was simulated for three potential breeding structures of the organic sector: organic breeding herds producing F1 gilts (OrgBS), a flower breeding system (FlowerBS) and a two-line rotation breeding system (RotBS). In FlowerBS, an organic purebred sow line is bred, using on-farm gilt replacement. The OrgBS with a Yorkshire X Landrace cross had the highest margin per sow place ((sic)779), followed by RotBS with Yorkshire X Landrace cross ((sic)706) and FlowerBS with Yorkshire sow line ((sic)677). In case that an organic purebred sow population of 5000 sows would be available, FlowerBS gave the highest genetic progress in terms of cost price reduction ((sic)3.72/slaughter pig per generation), followed by RotBS and OrgBS ((sic)3.60/slaughter pig per generation). For FlowerBS, additional costs will be involved for maintaining a dedicated breeding programme. In conclusion, OrgBS using conventional genetics is economically the most viable option for the organic pig sector. However, this structure has clear disadvantages in terms of risks with regard to disease transmission and market demand. FlowerBS using a dedicated purebred organic line will only be cost-effective if sow population size is sufficiently large. RotBS might be a viable alternative, especially in combination with artificial insemination (AI) boars that are ranked according to an organic selection index. Regardless of breeding structure, the Yorkshire sow line gave the highest prolificacy and the highest economic returns on organic herds

Estimação de parâmetros genéticos em tamanho de leitegada de suínos utilizando análises de características múltiplas Estimation of genetic parameters for litter size in pigs using multi-trait analyses

Registros de animais da raça Large White foram utilizados para estimar componentes de co-variâncias e parâmetros genéticos para a característica número de leitões nascidos como medida do tamanho de leitegada. Na obtenção dos componentes de co-variâncias e dos parâmetros genéticos, utilizou-se o método da Máxima Verossimilhança Restrita, com o algoritmo Livre de Derivadas, por meio do programa MTDFREML. O modelo misto continha o efeito fixo de grupo contemporâneo e os efeitos aleatórios genético aditivo direto e residual. Dados das primeiras quatro parições foram usados em duas análises: análises unicaracterísticas e análise multicaracterística separada em séries de análises bicaracterísticas, na qual cada parição foi tratada como característica diferente. As estimativas de herdabilidades aditivas diretas para as parições obtidas nas análises multicaracterísticas foram consistentes com as estimativas obtidas nas análises unicaracterísticas, que variaram de 0,14 a 0,20. Estimativas de correlação fenotípica foram menores que as correlações genéticas. As correlações genéticas foram menores que 0,75 em todas as parições, exceto entre a terceira e a quarta parição, cuja correlação foi alta (0,91). A menor correlação genética foi observada entre a primeira e a segunda ordem de parto (0,60).<br>Data from the first four parities of Large White pigs were used to estimate (co)variance components and genetic parameters for litter size (LS) in single trait and multi-trait analyses. The (co)variance components and genetic parameters were estimated by restricted maximum likelihood using the MTDFREML program. LS in each parity was considered a different trait and the models included contemporary group as fixed effect and additive direct genetic and residual as random effects. Heritability estimates of LS in different parities in single trait analyses ranged from 0.14 to 0.20. Estimates of heritability in multi-trait analyses were similar to those obtained in single trait analyses. Phenotypic correlation estimates were lower than the genetic ones. Genetic correlations between parities were lower than 0.75, except for the estimate between the third and fourth parities, which was the highest one (0.91). The smallest genetic correlation (0.60) was observed between the first and second parities