Effect of oral administration of protected DL- methionine on wool quality and production of pregnant Merino hoggets raised in the argentinian Patagonia

Little is known about the effect of protected methionine supplemented to grazing pregnant ewes. In the present trial, oral administration of protected DL- methionine was tested in terms of: mean fibre diameter (MFD), growth of fibre length (L), unwashed fleece weight (UFW) and staple strength (SS) in pregnant hoggets grazing Patagonian ranges. The relationship between the coeficient of variation of MFD (CVMFD) and (SS) was also established. One hundred Merino hoggets were allotted at random to ten groups of ten animals each. Individual groups were the experimental unit. Five groups were supplemented with protected DL-methionine (PM) at 2.5 g.animal-1.day-1, the rest were control (C). Mean fibre diameter was measured in samples from the shoulder region. The “dye banding” technique was used to assess L. Data were analyzed according to a lineal model. Differences for UFW were significant (p<0.05) (2.70 ± 0.13 kg and 3.00 ± 0.17 kg for C and PM respectively) as well as for L, 0.84 ± 0.06 mm for C and 1.07 ± 0.04 mm for PM. Neither differences for SS (p>0.05) nor for CVMFD were significative, values for the latter ranged from 17 to 19 %. Supplementation with protected DL-methionine allowed to improve production parameters, therefore it is a technique worthwhile considering when feeding pregnant hoggets grazing rangelands

A phasing and imputation method for pedigreed populations that results in a single-stage genomic evaluation

<p>Abstract</p> <p>Background</p> <p>Efficient, robust, and accurate genotype imputation algorithms make large-scale application of genomic selection cost effective. An algorithm that imputes alleles or allele probabilities for all animals in the pedigree and for all genotyped single nucleotide polymorphisms (SNP) provides a framework to combine all pedigree, genomic, and phenotypic information into a single-stage genomic evaluation.</p> <p>Methods</p> <p>An algorithm was developed for imputation of genotypes in pedigreed populations that allows imputation for completely ungenotyped animals and for low-density genotyped animals, accommodates a wide variety of pedigree structures for genotyped animals, imputes unmapped SNP, and works for large datasets. The method involves simple phasing rules, long-range phasing and haplotype library imputation and segregation analysis.</p> <p>Results</p> <p>Imputation accuracy was high and computational cost was feasible for datasets with pedigrees of up to 25 000 animals. The resulting single-stage genomic evaluation increased the accuracy of estimated genomic breeding values compared to a scenario in which phenotypes on relatives that were not genotyped were ignored.</p> <p>Conclusions</p> <p>The developed imputation algorithm and software and the resulting single-stage genomic evaluation method provide powerful new ways to exploit imputation and to obtain more accurate genetic evaluations.</p

Polymorphisms of the prion protein gene and their effects on litter size and risk evaluation for scrapie in Chinese Hu sheep

It is well known that scrapie is a fatal, neurodegenerative disease in sheep and goat, which belongs to the group of transmissible spongiform encephalopathies (TSEs) or prion diseases. It has been confirmed that the polymorphisms of prion protein gene (PRNP) at codons 136, 154, and 171 have strong relationship with scrapie in sheep. In the present study, nine polymorphisms of PRNP at codons 136, 154, and 171 and other six loci (at codons 101, 112, 127, 137, 138, and 152) were detected in 180 Chinese Hu sheep. All the alleles at codons 136, 154, and 171 have been identified and resulted in three new genotypes. The frequencies of predominant alleles were 85% (A136), 99.40% (R154), and 37.78% (Q171), respectively. The predominant haplotype ARQ has a relatively high frequency of 57.77%. The frequencies of dominant genotypes of ARR/ARQ and ARQ/ARQ were 30 and 26.67%, respectively. Three new found genotypes named ARQ/TRK, ARQ/TRR, and TRR/TRQ had the same lower frequencies (0.56%). The relationship of PRNP genotype with scrapie risk and litter size showed that the predominant genotypes are corresponded to the risk score of R1 (1.67%), R2 (32.22%), and R3 (42.22%). Just at the first parity, the individuals with ARH/ARH genotype had significantly larger litter size than the mean value and those with ARQ/ARQ and ARR/ARQ genotypes. In short, this study provided preliminary information about alleles and genotypes of PRNP in Chinese Hu sheep. It could be concluded that Hu sheep has a low susceptibility to natural scrapie, and the predominant PRNP genotype at least has no significant effect on litter size

One-step vs. multi-step methods for genomic prediction in presence of selection.

ABSTRACT.With the increasing availability of marker information in livestock, genomic selection methods can allow breeders to preselect animals on genotypes early in life. The combination of pedigree, phenotypic and genotypic data will increase genetic progress by decreasing the generational interval and increasing the accuracy of genetic merit estimates