2,119 research outputs found
Selection for growth, muscling and fatness alters the maternal performance and intermediary metabolism of Merino ewes
No full textThere is growing interest in selectively breeding Merinos with higher growth and muscling and lower fatness. The effects of selection for these traits on ewe intermediary metabolism, body composition, reproduction and milk production and on lamb birthweight, survival and growth were studied in a series of experiments and analyses.
Ewes with higher genetic propensity for early growth had higher mature weight, reproductive rate, lamb birthweight, ewe milk production and lamb growth rate. Ewes with higher growth also had a higher circulating level of growth hormone during lactation.
Ewes with higher genetic propensity for muscling had a higher reproductive rate and produced lambs that were lighter at birth, but this did not result in lower lamb survival. Ewes with higher muscling maintained a higher condition score which may be at least partly attributed to a lower response to adrenaline at the level of the muscle in these higher muscled ewes. Similarly higher muscled ewes had lower growth hormone concentration in lactation which would result in lower mobilisation of tissues. In addition peripheral tissues were less responsive to insulin in high muscled ewes and blood glucose levels were also higher during the non-breeding state in high muscled ewes.
The genetic fatness of ewes was positively associated with lamb birthweight but only when nutrition was restricted suggesting that ewes with a higher genetic propensity for fatness can buffer lamb birthweight under periods of poor nutrition. Ewes with higher genetic fatness had lower circulating growth hormone and a greater response to insulin providing potential mechanisms for the observed higher fatness. Furthermore, response to adrenaline at the level of liver was greater in ewes with higher fatness suggestive of a higher capacity for gluconeogenesis. The combined results of this work suggest that actively selecting Merino ewes to have higher growth, muscling and fatness is likely to have positive reproduction and therefore economic outcomes
Meeting with the Hebrew author Elias Hurwitz
No full textWhite paper; handpainted; on the reverse of Luftwaffe uniform pattern. Digitized posters are related to the activities of Jewish displaced persons drawn from the Records of Displaced Persons Camps and Centers in Germany (RG 294.2) Italy (RG 294.3) and Austria (RG 294.4) held by YIVO Archives. Please consult the historical note for those record groups for further information.Digital ImageDigital finding aid available
Obituary announcement about author and labor activist Sh. Mendelson
No full textBrown paper; handpainted. Digitized posters are related to the activities of Jewish displaced persons drawn from the Records of Displaced Persons Camps and Centers in Germany (RG 294.2) Italy (RG 294.3) and Austria (RG 294.4) held by YIVO Archives. Please consult the historical note for those record groups for further information.Digital ImageDigital finding aid available
Genetic correlations between bodyweight change and reproduction traits in Merino ewes depend on age
No full textMerino sheep in Australia experience periods of variable feed supply. Merino sheep can be bred to be more resilient to this variation by losing less bodyweight when grazing poor quality pasture and gaining more bodyweight when grazing good quality pasture. Therefore, selection on bodyweight change might be economically attractive but correlations with other traits in the breeding objective need to be known. The genetic correlations (rg) between bodyweight, bodyweight change, and reproduction were estimated using records from ~7350 fully pedigreed Merino ewes managed at Katanning in Western Australia. Number of lambs and total weight of lambs born and weaned were measured on ~5300 2-year-old ewes, ~4900 3-year-old ewes and ~3600 4-year-old ewes. On a proportion of these ewes bodyweight change was measured: ~1950 two-year-old ewes, ~1500 three old ewes and ~1100 four-year-old ewes. The bodyweight measurements were for three periods. The first period was during mating period over 42 days on poor pasture. The second period was during pregnancy over 90 days for ewes that got pregnant on poor and medium quality pasture. The third period was during lactation over 130 days for ewes that weaned a lamb on good quality pasture. Genetic correlations between weight change and reproduction were estimated within age classes. Genetic correlations were tested to be significantly greater magnitude than zero using likelihood ratio tests. Nearly all bodyweights had significant positive genetic correlations with all reproduction traits. In two-year old ewes, bodyweight change during the mating period had a positive genetic correlation with number of lambs weaned (rg = 0.58); bodyweight change during pregnancy had a positive genetic correlation with total weight of lambs born (rg = 0.33) and a negative genetic correlation with number of lambs weaned (rg = - 0.49). All other genetic correlations were not significantly greater magnitude than zero but estimates of genetic correlations for three-year-old ewes were generally consistent with these findings. The direction of the genetic correlations mostly coincided with the energy requirements of the ewes, and the stage of maturity of the ewes. In conclusion, optimized selection strategies on bodyweight changes to increase resilience will depend on the genetic correlations with reproduction, and are dependent on age
Investigation of growth traits in Turkish Merino lambs using multi-locus GWAS approaches: Middle Anatolian Merino
No full textAbstract This study explored the genetic basis of growth traits in Middle Anatolian Merino lambs using multi-locus genome-wide association study (GWAS) analyses. Descriptive statistics indicated moderate heritability (h² = 0.363) for birth weight (BW) and (h² = 0.309) for weaning weight (WW), both statistically significant (p < 0.001). Strong genetic correlations were observed between WW and BW (rG = 0.922) and WW and Kleiber ratio (KR, rG = 0.896), implying that simultaneous improvements may be possible through targeted selection. Five multi-locus methods (mrMLM, FASTmrMLM, pLARmEB, FASTmrEMMA, and ISIS EM-BLASSO) were used to identify the polygenic basis of the traits. For BW and WW, 20 and 18 significant SNPs (LOD ≥ 5) were detected, respectively, with some SNPs co-detected by multiple methods. In contrast, only 10 significant SNPs were identified for KR, all exclusively by the ISIS EM-BLASSO approach. Pathway analyses within ± 100 Kb of associated SNPs revealed genes and pathways influencing these traits, which could be leveraged in future breeding programs for enhanced growth performance. The identified SNPs, particularly those associated with BW and WW traits, could facilitate genomic selection if validated in larger and more diverse populations
Genetic aspects of greasy wool colour assessments in Merino sheep
No full textWool colour is an important determinant of wool price, especially in fine and superfine Merinos. While objective measurement is not routinely available on farm many Merino breeders subjectively score sheep on greasy wool colour on farm for selection purposes. This study examines subjective greasy wool colour scores from an industry data set. Wool colour scores ranged from 1 to 5, with a score of 1 being superior (whiter) to a score of 5. Age and birth type significantly affected greasy wool colour scores. Older sheep had lower colour scores (whiter wool) and multiple born lambs had lower scores than singles. Greasy wool colour, scored in the yards and wool shed, are moderately heritable, 0.35 and 0.31, respectively. Both greasy wool colour scores also had a small but significant maternal genetic heritability of 0.03. Sheep with heigher body weight (rg=0.21 to 0.23) and greasy fleece weight (rg=0.29 to 0.34) had more greasy wool colour. Greasy wool colour assessed at shearing in the wool shed was negatively genetically correlated with fat depth (rg=-0.39) and mean fibre curvature (rg=-0.22). The remaining traits examined in this study were not significantly correlated with greasy wool colour scores. The correlations involving these other traits indicate that wool colour can be improved genetically without detrimental effects to these other traits. Greasy wool colour assessed in the yards is the same trait genetically (rg=0.94) as that assessed at shearing in the wool shed. Wool colour scores recorded across ages are highly correlated indicating that from a breeding program point of view wool colour only needs to be measured at one time throughout an animal's life. Greasy wool colour is moderately repeatable (0.46) and therefore will respond to selection
Genetic correlations between body weight change and reproduction traits in Merino ewes depend on age
No full textMerino sheep in Australia experience periods of variable feed supply. Merino sheep can be bred to be more resilient to this variation by losing less BW when grazing poor quality pasture and gaining more BW when grazing good quality pasture. Therefore, selection on BW change might be economically attractive but correlations with other traits in the breeding objective need to be known. The genetic correlations (rg) between BW, BW change, and reproduction were estimated using records from approximately 7,350 fully pedigreed Merino ewes managed at Katanning in Western Australia. Number of lambs and total weight of lambs born and weaned were measured on approximately 5,300 2-yr-old ewes, approximately 4,900 3-yrold ewes, and approximately 3,600 4-yr-old ewes. On a proportion of these ewes BW change was measured: approximately 1,950 2-yr-old ewes, approximately 1,500 3-yr-old ewes, and approximately 1,100 4-yr-old ewes. The BW measurements were for 3 periods. The first period was during mating period over 42 d on poor pasture. The second period was during pregnancy over 90 d for ewes that got pregnant on poor and medium quality pasture. The third period was during lactation over 130 d for ewes that weaned a lamb on good quality pasture. Genetic correlations between weight change and reproduction were estimated within age classes. Genetic correlations were tested to be significantly greater magnitude than 0 using likelihood ratio tests. Nearly all BW had significant positive genetic correlations with all reproduction traits. In 2-yr-old ewes, BW change during the mating period had a positive genetic correlation with number of lambs weaned (rg = 0.58); BW change during pregnancy had a positive genetic correlation with total weight of lambs born (rg = 0.33) and a negative genetic correlation with number of lambs weaned (rg = -0.49). All other genetic correlations were not significantly greater magnitude than 0 but estimates of genetic correlations for 3-yr-old ewes were generally consistent with these findings. The direction of the genetic correlations mostly coincided with the energy requirements of the ewes and the stage of maturity of the ewes. In conclusion, optimized selection strategies on BW changes to increase resilience will depend on the genetic correlations with reproduction and are dependent on age
Sweeping has no effect on renormalized turbulent viscosity
No full textWe perform renormalization group analysis (RG) of the Navier-Stokes equation in the presence of constant mean velocity field , and show that the renormalized viscosity is unaffected by , thus negating the ``sweeping effect", proposed by Kraichnan [Phys. Fluids {\bf 7}, 1723 (1964)] using random Galilean invariance. Using direct numerical simulation, we show that the correlation functions for and differ from each other, but the renormalized viscosity for the two cases are the same. Our numerical results are consistent with the RG calculations
Genetic correlations between body weight change and reproduction traits in Merino ewes depend on age
No full textMerino sheep in Australia experience periods of variable feed supply. Merino sheep can be bred to be more resilient to this variation by losing less BW when grazing poor quality pasture and gaining more BW when grazing good quality pasture. Therefore, selection on BW change might be economically attractive but correlations with other traits in the breeding objective need to be known. The genetic correlations (rg) between BW, BW change, and reproduction were estimated using records from approximately 7,350 fully pedigreed Merino ewes managed at Katanning in Western Australia. Number of lambs and total weight of lambs born and weaned were measured on approximately 5,300 2-yr-old ewes, approximately 4,900 3-yr-old ewes, and approximately 3,600 4-yr-old ewes. On a proportion of these ewes BW change was measured: approximately 1,950 2-yr-old ewes, approximately 1,500 3-yr-old ewes, and approximately 1,100 4-yr-old ewes. The BW measurements were for 3 periods. The first period was during mating period over 42 d on poor pasture. The second period was during pregnancy over 90 d for ewes that got pregnant on poor and medium quality pasture. The third period was during lactation over 130 d for ewes that weaned a lamb on good quality pasture. Genetic correlations between weight change and reproduction were estimated within age classes. Genetic correlations were tested to be significantly greater magnitude than 0 using likelihood ratio tests. Nearly all BW had significant positive genetic correlations with all reproduction traits. In 2-yr-old ewes, BW change during the mating period had a positive genetic correlation with number of lambs weaned (rg = 0.58); BW change during pregnancy had a positive genetic correlation with total weight of lambs born (rg = 0.33) and a negative genetic correlation with number of lambs weaned (rg = -0.49). All other genetic correlations were not significantly greater magnitude than 0 but estimates of genetic correlations for 3-yr-old ewes were generally consistent with these findings. The direction of the genetic correlations mostly coincided with the energy requirements of the ewes and the stage of maturity of the ewes. In conclusion, optimized selection strategies on BW changes to increase resilience will depend on the genetic correlations with reproduction and are dependent on age
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