Poor cow fertility has been identified as a growing problem in Irish dairy herds. In this seasonal calving and the grass based production system, poor fertility results in a significant loss in farm income (Veerkamp et al., 2001) due to forced culling or a shift in calving pattern. In order to arrest this trend, subsequent calving interval (CIV) and survival to the next lactation (SUV) has been...

A genetic marker is a gene or DNA sequence with known localization on a chromosome. It can be de-scribed as a variation that can be measured or detected by a suitable method, and can be used subsequently to detect the presence of a specific genotype. Such variations occurring at chromosomal or DNA level can serve as genetic markers. The progress in development of molecular markers suggests thei...

Net feed intake (NFI) is a moderately heritable feed efficiency trait that has been shown to be genetically independent of ADG and BW in beef cattle. Objectives of this study were to characterize NFI in growing bulls, and to examine phenotypic correlations between NFI and performance, body composition, and fertility traits. Net feed intake was positively correlated phenotypically with feed conv...

Milk production, fertility, longevity and health records, were extracted from databases of two milk recording organisations in the United Kingdom for the first three lactations of the Holstein-Friesian breed. These included data related to health events (mastitis and lameness), voluntarily recorded on a proportion of farms. The data were analysed to calculate disease incidence levels and to est...

It has been suggested that traits associated with fitness, such as fertility, may have proportionately more genetic variation arising from non-additive effects than traits with higher heritability, such as milk yield. Here, we performed a large genome scan with 408,255 single nucleotide polymorphism (SNP) markers to identify chromosomal regions associated with dominance and epistatic (pairwise ...

Data from 364 ewes of Sardi (S), D'man (D), S x DS, DS x S, S x D, D x S (F1), F2, D x DS and DS x D breed groups mated to F1 rams were analyzed for fertility, number of lambs born alive, litter size at weaning, litter weight at weaning per ewe joined and mean lamb weight at 60 d. Each ewe was exposed in two seasons and had one or two lambings. Effects of breed group were significant for all tr...

We have identified chromosomal regions containing quantitative trait loci (QTLs) specifying life history traits in recombinant-inbred strains of the nematode Caenorhabditis elegans. This approach also allows us to examine epistatic interactions between loci and pleiotropic effects on different traits at specific loci. QTLs for mean life span were identified on chromosomes II (near stP101), IV (...