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Juiz de Fora, Brazil

Kim E.-S.,U.S. Department of Agriculture | Sonstegard T.S.,U.S. Department of Agriculture | Silva M.V.G.B.,U.S. Department of Agriculture | Silva M.V.G.B.,Embrapa Dairy Cattle Center | And 2 more authors.
Animal Genetics | Year: 2014

DNA markers associated with quantitative trait loci (QTL) affecting host tolerance to gastrointestinal (GI) parasite infection are ideal targets for marker-assisted selection. However, few studies in cattle have attempted to identify this type of QTL due to the difficulty of generating accurate phenotypic data from a resource population with adequate statistical power for detection. For this effort, we amassed fecal egg count (FEC) measures from annual natural field challenges with GI nematodes that spanned 12 different contemporary groups of Angus calves (1992-2000) derived from a closed breeding population. FEC and blood pepsinogen measures were taken weekly over a 26-week period post-weaning, and the FEC data were Box-Cox transformed to normalize the distribution of phenotypes. These 305 test animals and more than 100 founding animals from the extended pedigree were genotyped across 190 microsatellites markers. The genome-wide analyses identified a suggestive genome-wide QTL on bovine chromosome (Chr) 8 (P < 0.002) and nominal QTL on Chr 4, 12 and 17 (P < 0.05). These findings were unique for cattle, and some corresponded to previously identified QTL locations for parasite-related traits in sheep to provide genome locations for further fine mapping of parasite resistance/susceptibility in Angus cattle. © Published 2013. This article is a U.S. Government work and is in the public domain in the USA. Source

Xavier D.F.,Embrapa Dairy Cattle Center | da Silva Ledo F.J.,Embrapa Dairy Cattle Center | de Campos Paciullo D.S.,Embrapa Dairy Cattle Center | Urquiaga S.,Embrapa Agrobiologia | And 2 more authors.
Nutrient Cycling in Agroecosystems | Year: 2014

In the south-eastern region of Brazil there are millions of hectares of deforested, almost-treeless hillsides with sparse ground-cover of grasses of African origin. For the establishment of more productive pastures in these areas, silvopastoral systems (SPSs) have been recommended, and the objective of this study was to quantify the N fluxes in the soil/plant/ animal systems as a means compare the sustainability of a SPS planted with legume trees (Acacia mangium and Mimosa artemisiana) and eucalyptus, compared to that of a grass-alone Brachiaria decumbens (BDH) pasture. The annual live weight gain of Zebu × Friesian heifers, assessed 5 years after pasture establishment, was significantly higher on the SPS than on the grass-alone pasture, at 205 and 177 kg head-1 year-1 respectively. The N deposited as animal excreta (38–49 kg ha -1 for BDH and SPS, respectively), especially urine, is considered to be much more susceptible to loss than N derived from decomposing plant litter, and was found to be much less than the N recycled though the grass litter (107 and 114 kg ha-1 , respectively) in both systems. The extra N recycled in tree-leaf and grass litter increased this by 34 kg N ha-1 in the SPS and we conclude that this would contribute to sustain forage productivity. The added advantage of trees in the provision of shade for the animals and protection from soil erosion should further contribute to the long term sustainable productivity of this SPS. © 2014 Springer Science+Business Media Dordrecht. Source

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