Efeitos genéticos e não-genéticos sobre o intervalo de parto em fêmeas suínas no Sudeste do Brasil / Genetic and environmental effects on the farrowing interval in sows in the southeastern region of Brazil

The effect of environmental and genetic effects on the farrowing interval in Dalland (C-40) sows in the Southeast of Brazil was studied. Data consisting of 1,013 farrowing intervals recorded in two herds were analyzed, using a model that included the sire and the dam as random effects and the year of farrowing, the herd and the farrowing season as fixed effects, plus the covariables sow's age at farrowing, litter size at birth, lactation length and weaning-estrus interval. For the farrowing interval first only, variance components were estimated by REML, with an animal model that included, as fixed effect, a contemporary group and, as random effects, the additive genetic variance and the error. The mean farrowing interval was 140.9+5.7 days, with a 4.0 percent coefficient of variation. Variance analysis showed no effect of either year, season of farrowing or herd on the farrowing interval. The sire effect was not important for the farrowing interval, but the dam represented an important source of variation. The total number of piglets born and the sow's age at farrowing had no influence on the farrowing interval. The length of lactation exerted an influence on the farrowing interval, accounting for 19.4 percent of the total variation of this trait. Likewise, the linear regression of the weaning-estrus interval in relation to the farrowing interval was highly significant, accounting for 51.7 percent of the total variation. The heritability estimate was 0.00, suggesting that no genetic gain can be obtained by selection for a shorter farrowing interval.

Efeitos genéticos e ambientais sobre a idade à primeira concepção de fêmeas suínas / Estimates of genetic and environmental effects on age at first conception of gilts

The genetic and environmental factors that affect age at first conception (AFC) of gilts were evaluated, using 466 observations of Dalland animals (C-40). The software program MTDFREML was used to assess the genetic parameters on an animal model that included as fixed effect, contemporary group and, as random effects, the additive genetic, the common litter and the error. Mean value of AFC was 241.12±25.9 days, with CV of 8.5 percent. Variance analysis showed that year (P<0.01), season (P<0.01) and herd effects (P<0.01) were important sources of variation of AFC. The throat effect (P=0.34) was not important for the AFC, but the mother of the gilts (P<0.01) was an important source of variation. The heritability estimate was 0.44±0.14 that this trait would yield genetic gain as a response to the selection.

Desempenho, características de carcaça e viabilidade econômica de coelhos sexados abatidos em diferentes idades / Performance, carcass characteristics and economic viability of sexed rabbits slaughtered at different ages

Avaliaram-se o desempenho, as características de carcaça e a viabilidade econômica de coelhos sexados abatidos em diferentes idades. Foram usados 100 coelhos (50 machos e 50 fêmeas), em delineamento de blocos inteiramente ao acaso e arranjo fatorial 2×2 (dois sexos e duas idades ao abate), com quatro tratamentos e cinco repetições. Os coelhos foram desmamados aos 35 e abatidos aos 75 ou 90 dias de idade. Não houve diferença entre sexo (P>0,05) nos parâmetros avaliados. Os animais abatidos aos 90 dias (P<0,001) eram mais pesados e consumiram (diário) mais ração. Os abatidos aos 75 dias (P<0,001) ganharam mais peso (diário) e apresentaram melhor conversão alimentar. Coelhos abatidos aos 90 dias de idade tiveram maiores pesos relativos de carcaça (P<0,04), de coxa (P<0,001), de gordura interna (P<0,001) e de fígado (P<0,01) e, ainda, apresentaram maior peso final e melhores características de carcaça, cuja venda foi mais lucrativa quando realizada aos 75 dias ou quando foram abatidos aos 90 dias de idade.

Performance, carcass characteristics and economic viability of sexed rabbits slaughtered at different ages were evaluated. One-hundred rabbits (50 males and 50 females) were assigned to a completely randomized block design in a factorial arrangement of 2×2 (two sexes and two slaughter ages), with four treatments and five replicates. The rabbits weaned at 35 were slaughtered at 75 and 90 days of age. No effect of sex (P>0.05) on the evaluated parameters was observed. Animals slaughtered at 90 days were heavier(P<0.001), had a higher daily feed intake and a higher carcass weight than animals slaughtered at 75 days which showed higher daily weight gain and better feed: gain ratio. Rabbits slaughtered at 90 days of age had higher carcass weight (P<0.04), thigh (P<0.005), internal fat (P<0.001) and liver (P<0.01). They also showed better carcass characteristics. High rentability was obtained alternatively for animals sold alive at 25 days of age or slaughtered at 90 days of age.

Genetic diversity in wild (Sus scrofa scrofa) and domestic (Sus scrofa domestica) pigs and their hybrids based on polymorphism of a fragment of the D-loop region in the mitochondrial DNA

We examined the variation in mitochondrial DNA by sequencing the D-loop region in wild and domestic (large-white breed) pigs, in hybrids between domestic and wild pigs, and in Monteiro pigs. A D-loop fragment of approximately 330 bp was amplified by PCR. Sequencing of DNA amplicons identified haplotypes previously described as European and Asian types. Monteiro pigs and wild pigs had European haplotypes and domestic pigs had both European and Asian haplotypes.