Crossbreeding impacts on caecal bacterial count and antibody titres in chickens.

1. A crossbreeding experiment was conducted using 20 sires and 120 dams from each Fayoumi (F) and Rhode Island Red (R) breeds. The F1 chicks of ½F½R and their reciprocal ½R½F crosses were used to estimate direct, maternal and heterotic effects.2. The caecal bacterial counts of Salmonella typhimurium and Enterococcus faecium and the IgA, IgG and IgM antibody titres were determined. Chicks of each genetic group (120 birds) were divided into three groups (40 birds per group) and chicks of the first group were assigned as the control group, while the second group was inoculated with S. typhimurium and E. faecium at 7 and 10 d of age (106 cfu/chick) and the third was inoculated with S. typhimurium at 10 d of age (106 cfu/chick).3. The generalised least square procedure was used to estimate cross-breeding effects. The S. typhimurium counts in the R breed was highly significant, followed by ½F½R cross, ½R½F cross, and F breed. The differences among genetic groups in E. faecium counts and caecal pH was not significant. The estimates of IgA, IgG, and IgM antibody titres were highly significant in the F breed, followed by ½R½F cross, ½F½R cross, and the R breed.4. The estimates of direct additive effects were highly significant F breed for the counts of S. typhimurium and antibody titres of IgA, IgG, and IgM. The maternal effects were highly significant F breed for S. typhimurium, E. faecium count, and antibody titres of IgA, IgG, and IgM. Estimates of direct heterosis were significant for S. typhimurium count and IgA antibody titre but not significant for E. faecium count, caecal pH, and antibody titres of IgG and IgM.5. The results showed that the Fayoumi breed could be used in breeding programmes to improve immunity traits against S. typhimurium in chickens.

Efecto de la endocría sobre habilidad combinatoria del rendimiento y calidad en zapallo ( Cucurbita moschata Duchesne) / Inbreeding effect in combinatorial ability of yield and quality on butternut squash ( Cucurbita moschata Duchesne)

RESUMEN El zapallo Cucurbita moschata Duchesne es una hortaliza para diversos procesos culinarios y agroindustriales, por su color, sabor y textura; sin embargo, estas características cambian dependiendo del cultivar. Con base en 6 progenitores, 15 híbridos F1, sin incluir los recíprocos, se estudió el efecto de la endocría en la habilidad combinatoria (HC), de caracteres asociados con el rendimiento y la calidad del fruto del zapallo, en dos localidades, Candelaria y Buga, Valle del Cauca, Colombia. Se usó cruzamientos dialélicos y progenitores con diferente grado de endocría (S0xS0, S1xS1 y S2xS2). Se utilizó el método 2 y modelo I, propuesto por Griffing y el análisis de Hallauer & Miranda, para evaluar la habilidad combinatoria general (HCG) y específica (HCE) del rendimiento y la calidad del fruto, con fines agroindustriales. Todos los caracteres evaluados variaron entre generaciones de endocría. Se detectó interacción entre generación de endocría por localidad para todos los caracteres (P<0,01), con excepción de almidón (AL) y caroteno total (CT) en fruto. La HCG y HCE no se ajustaron a un patrón de comportamiento, debido a la variación de los progenitores en la susceptibilidad a la endocría. Los progenitores con HCG altamente significativa (P<0,01) para producción, fueron: 79S0, 79S1, 80S0 y 34S1, en Candelaria y 79S0, 79S1, 79S2, 34S0, 6S0, 6S1, 2S1 y 2S2, en Buga. Los mejores híbridos con alta HCE y alto rendimiento y calidad, para la localidad Candelaria, fueron: 2x28-S0, 2x80-S0, 28x80-S0 y 80x34 y para la localidad Buga: 2x6-S1, 80x34-S1, 2x80-S2 y 79x34-S2.

ABSTRACT Butternut squash, Cucubita moschata Duchesne, is a vegetable used for various culinary and agro-industrial processes due to its colour, flavour and texture; however, these characteristics change depending on the cultivar. Based on 6 parents, 15 F1 hybrids, not including reciprocals, the effect of inbreeding on the combinatorial ability (HC) of characters associated with the performance and quality of Butternut squash fruit was studied; in two locations, Candelaria and Buga, Valle del Cauca-Colombia. Diallel and progenitor crosses with different degrees of inbreeding (S0xS0, S1xS1 and S2xS2) were used. Method 2 and model I proposed by Griffing and the Hallauer & Miranda analysis were applied to assess the general combinatorial (HCG) and specific combinatorial ability (HCE) of the yield and quality of the fruit, for agroindustrial purposes. All evaluated characters varied between inbreeding generations. Interaction between inbreeding generation by locality was detected for all characters (P <0.01), with the exception of starch (AL) and total carotene (CT) in fruit. The HCG and HCE did not adjust to expected behaviour pattern, due to the variation of parents to inbreeding susceptibility. The parents with highly significant HCG (P <0.01) for production were 79S0, 79S1, 80S0 y 34S1 in Candelaria and 79S0, 79S1, 79S2, 34S0, 6S0, 6S1, 2S1 y 2S2 to Buga. The best hybrids with high HCE and high performance and quality, for Candelaria locality were: 2x28-S0, 2x80-S0, 28x80-S0 and 80x34 and for locality Buga: 2x6-S1, 80x34-S1, 2x80-S2 and 79x34-S2.