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K A Leymaster - One of the best experts on this subject based on the ideXlab platform.
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evaluation of associations between prion haplotypes and growth carcass and meat quality traits in a dorset Romanov sheep population
Journal of Animal Science, 2006Co-Authors: B J Isler, B A Freking, R M Thallman, Michael P Heaton, K A LeymasterAbstract:There is concern about potential antagonistic correlated responses due to intensive selection for scrapie-resistant haplotypes of the prion (PRNP) gene in sheep. The objective of the present research was to test for associations of PRNP haplotypes for codons 136, 154, and 171 with growth, carcass, and meat quality traits in an F 2 Dorset x Romanov population (n = 415) segregating the 2 callipyge alleles. Haplotypes of the 3 PRNP codons were determined for each sheep, and breed of origin of each gamete was predicted by genotyping 6 microsatellite markers flanking the PRNP locus. Twenty-five growth, carcass, and meat quality traits were evaluated. Data were analyzed using a basic model consisting of fixed effects of year, sex, and callipyge genotype, the random effect of sire, and 7 covariates corresponding to the probability that a lamb inherited a specific PRNP haplotype of either Dorset or Romanov origin. A fixed effect of litter size was added to the model for growth traits. The model for carcass traits contained the linear and quadratic effects of chilled carcass weight and the interactions among callipyge genotype and linear and quadratic terms. For meat quality traits, the model contained chilled carcass weight as a covariate and the interaction between callipyge genotype and chilled carcass weight. A contrast between the resistant ARR haplotype and the average effect of other PRNP haplotypes was tested to investigate the effects of potential selection for ARR within each breed of origin (Dorset, ARR vs. ARQ, VRQ, and AHQ; Romanov, ARR vs. ARQ and VRQ). There was limited evidence that selecting for scrapie resistance would cause correlated responses due to linkage disequilibrium. Associations of only 3 traits with PRNP haplotypes were detected in either breed of origin. In Romanov, the ARR haplotype was associated with longer carcasses (P < 0.013), narrower rumps (P = 0.038), and less marbling (P = 0.022) than the average of ARQ and VRQ haplotypes. No significant contrasts were detected for Dorset. This study is the first to account for breed of origin while investigating haplotype associations in an F 2 population. This study provided limited evidence of associations between PRNP haplotypes and growth, carcass, and meat quality traits.
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evaluation of dorset finnsheep Romanov texel and montadale breeds of sheep iv survival growth and carcass traits of f1 lambs
Journal of Animal Science, 2004Co-Authors: B A Freking, K A LeymasterAbstract:Theobjectives ofthisstudywere toesti- mate effectsof sirebreed (Dorset,Finnsheep, Romanov, Texel, and Montadale), and dam breed (Composite III and Northwestern whiteface) on survival, growth, car- cass, and composition traits of F1 lambs. Effects of mat- ing season (August, October, and December) were esti- mated for survival and growth traits. Data were col- lected on 4,320 F1 lambs sired by 102 purebred rams over 3 yr. Birth weight was recorded on all lambs, and subsequent BW were adjusted to 56 (weaning), 70, and 140 d of age (n = 3,713, 3,654, and 3,579 observations, respectively). Survival of dam-reared progeny (n = 4,065) to weaning was recorded. Each year, wethers from October matings were slaughtered in three groups at 25, 29, and 33 wk of age to obtain carcass data (n = 546). In addition to standard carcass traits, resistive impedance measurements were recorded on the warm carcass to predict lean mass. Dam breed (P = 0.37) did not influence lamb survival to weaning, but sire breed (P <0.05)wasimportant.Romanov-siredlambsexcelled in survival rate to weaning (94.1%), followed by Finn- sheep(93.0%),Texel(90.7%),Dorset(90.0%),andMont- adale(89.1%) siredprogeny. Lower(P <0.01) postwean- ing growth rate was observed for Texel (267 g/d) and Finnsheep (272 g/d) sired progeny than for Dorset (285 g/d), Montadale (282 g/d), and Romanov (278 g/d) sired progeny. Sire breed and dam breed were generally sig- nificant for most carcass traits. Breed differences in distribution of carcass fat and carcass shape were de- tected; however, carcass composition was similar for all sire breeds when compared at a constant carcass weight. When evaluated at a constant 12th-rib fat depth, carcasses of lambs from Finnsheep, Romanov, and Texel sires produced 1 to 1.5 kg less (P < 0.001) predicted lean mass per lamb than carcasses of lambs from Dorset and Montadale sires. These experimental results provide information about the direct breed ef- fects for survival, growth, and carcass traits of these breeds and their potential use in crossbreeding systems.
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evaluation of dorset finnsheep Romanov texel and montadale breeds of sheep iii wool characteristics of f1 ewes
Journal of Animal Science, 2004Co-Authors: C J Lupton, B A Freking, K A LeymasterAbstract:: An experiment was designed to evaluate the effects of five sire breeds (Dorset, Finnsheep, Romanov, Texel, and Montadale), two dam breeds (Composite III [CIII] and northwestern whiteface [WF]), and three shearing seasons (December, February, and April, corresponding to August, October, and December breeding seasons) and their interactions on wool and other characteristics of F1 ewes. Fleeces were collected and characterized from six 2-yr-old F1 ewes representing each of the 90 sire breed x dam breed x shearing season x year (three) subclasses. Characteristics measured objectively were grease and clean fleece weights, clean yield, mean fiber diameter and SD, and mean staple length and SD. Visual assessments of fleece color were also made. Data collected on the F1 ewes were analyzed using a mixed model analysis of variance procedure. The model included fixed effects of year of birth, sire breed, dam breed, shearing season, six two-way interactions, and the three-way interaction of sire breed x dam breed x shearing season. The random effect of individual sire within year of birth x sire breed was also fitted. Texel- and Montadale-sired ewes produced more clean wool (P < 0.05) (approximately 0.24 kg) than Dorset-, Finnsheep-, and Romanov-sired ewes. Texel-sired ewes produced the coarsest wool (28.7 microm) (P < 0.05), whereas Romanov-sired ewes produced the finest (24.9 microm) and longest (9.12 cm) fleeces (P < 0.05). Ewes from WF dams produced more and finer wool (0.15 kg and 2.7 microm) than ewes from CIII dams (P < 0.001). Ewes shorn in December produced more, coarser, and longer wool (P < 0.05) than those shorn in February and April. This trend in wool production is opposite to that in conception rate (reported previously). Romanov-sired ewes produced the lowest percentage of white fleeces (62.6%), whereas Dorset-sired ewes produced the most (P < 0.001) white fleeces (96.3%). Estimates of heritability were calculated for grease and clean fleece weights (0.36), percentage of clean yield (0.31), average fiber diameter and SD (0.86 and 0.42, respectively), and average staple length and SD (0.49 and 0.00, respectively). Although necessary for a thorough evaluation of these 10 types of crossbred ewes, it is estimated that wool income would only constitute a small portion (1 to 5%) of overall income from sheep of this type.
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evaluation of dorset finnsheep Romanov texel and montadale breeds of sheep v reproduction of f1 ewes in spring mating seasons
Journal of Animal Science, 2004Co-Authors: Eduardo Casas, B A Freking, K A LeymasterAbstract:Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed (Composite III (CIII) and north- western whiteface (WF)), mating season (March and May), and their interactions on reproductive traits of mature F1 ewes in spring mating seasons. A total of 1,099 F1 ewes produced 1,754 litters of 2,995 lambs from exposures to Suffolk rams during March and May mating seasons in 1995 through 1999. Fertility rate and ewe longevity were measured. Number born and litter birth weight were recorded, and number and weight at weaning and 20 wk of age were analyzed separately for dam- and nursery-reared litter mates. Total productivity from 4 to 6 yr of age for each ewe entering the breeding flock was calculated as the sum of 20-wk weights for dam-reared lambs and separately for nursery-reared lambs. Interactions of sire breed × mating season, ewe age × mating season, and ewe age × dam breed were often significant. Interactive effects of sire breed and mating season on fertility rate (P < 0.001) were primarily due to differences in magnitude. Fertility rates of sire breeds for March and May mat- ings, respectively, were 92 and 89% for Romanov, 91 and 72% for Finnsheep, 90 and 52% for Texel, 88 and
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evaluation of dorset finnsheep Romanov texel and montadale breeds of sheep i effects of ram breed on productivity of ewes of two crossbred populations
Journal of Animal Science, 2000Co-Authors: B A Freking, K A Leymaster, L D YoungAbstract:: Effects of Dorset, Finnsheep, Romanov, Texel, and Montadale breeds for performance as sires were estimated in the initial phase of a comprehensive evaluation of these breeds as contributors to sheep crossbreeding systems. Objectives were to evaluate the effects of ram breed, ewe breed, season of mating, and two-way interactions. Rams from the five breeds were single-sire-mated with ewes from two breed types to produce lambs over a 3-yr period. Ewes were assigned to one of three distinct 35-d mating seasons initiated each year in August, October, and December. A different sample of six rams per breed was used each year across all three seasons, and each ram was penned with ewes of both breeds. Traits evaluated and number of ewe records were conception rate and litter weaning weight per ewe exposed (n = 3,261) and number born, litter birth weight, average birth weight, number weaned, and litter weaning weight per ewe lambing (n = 2,751). Ram breed and ewe breed interacted (P < .01) for conception rate and litter weaning weight per ewe exposed, implicating mating preferences, particularly of Romanov rams. In mixed groups of ewes exposed to Romanov rams, conception rate was 12.7% lower and litter weight weaned was 8.4 kg lower in the ewe breed presumably less preferred for mating by the rams. On a per ewe exposed basis, Romanov-sired litters produced either the largest or the smallest values for litter weaning weight, depending on the breed of ewe. Effects of ram breed on number born and litter birth weight interacted (P < .05) with season of mating. The largest litters within each ram breed were associated with the October mating season. Montadale and Romanov rams sired larger and heavier litters from August matings than from December matings, whereas the opposite was true for Dorset-sired litters. Texel- and Finnsheep-sired litters were similar in size and weight from August and December matings. Breed of ram differences affected per ewe lambing productivity measurements (P < .01). Differences between ram breeds for ewe productivity were noted, with increased number born and improved survival of crossbred progeny to weaning for Romanov-sired litters. These results may have implications for using these ram breeds as sires in different crossbreeding systems. Structured mating systems or the creation of new composite populations involving these breeds could be used to match the resources, environment, and market of specific production situations.
B A Freking - One of the best experts on this subject based on the ideXlab platform.
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evaluation of associations between prion haplotypes and growth carcass and meat quality traits in a dorset Romanov sheep population
Journal of Animal Science, 2006Co-Authors: B J Isler, B A Freking, R M Thallman, Michael P Heaton, K A LeymasterAbstract:There is concern about potential antagonistic correlated responses due to intensive selection for scrapie-resistant haplotypes of the prion (PRNP) gene in sheep. The objective of the present research was to test for associations of PRNP haplotypes for codons 136, 154, and 171 with growth, carcass, and meat quality traits in an F 2 Dorset x Romanov population (n = 415) segregating the 2 callipyge alleles. Haplotypes of the 3 PRNP codons were determined for each sheep, and breed of origin of each gamete was predicted by genotyping 6 microsatellite markers flanking the PRNP locus. Twenty-five growth, carcass, and meat quality traits were evaluated. Data were analyzed using a basic model consisting of fixed effects of year, sex, and callipyge genotype, the random effect of sire, and 7 covariates corresponding to the probability that a lamb inherited a specific PRNP haplotype of either Dorset or Romanov origin. A fixed effect of litter size was added to the model for growth traits. The model for carcass traits contained the linear and quadratic effects of chilled carcass weight and the interactions among callipyge genotype and linear and quadratic terms. For meat quality traits, the model contained chilled carcass weight as a covariate and the interaction between callipyge genotype and chilled carcass weight. A contrast between the resistant ARR haplotype and the average effect of other PRNP haplotypes was tested to investigate the effects of potential selection for ARR within each breed of origin (Dorset, ARR vs. ARQ, VRQ, and AHQ; Romanov, ARR vs. ARQ and VRQ). There was limited evidence that selecting for scrapie resistance would cause correlated responses due to linkage disequilibrium. Associations of only 3 traits with PRNP haplotypes were detected in either breed of origin. In Romanov, the ARR haplotype was associated with longer carcasses (P < 0.013), narrower rumps (P = 0.038), and less marbling (P = 0.022) than the average of ARQ and VRQ haplotypes. No significant contrasts were detected for Dorset. This study is the first to account for breed of origin while investigating haplotype associations in an F 2 population. This study provided limited evidence of associations between PRNP haplotypes and growth, carcass, and meat quality traits.
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Evaluation of associations between prion haplotypes and growth, carcass, and meat quality traits in a Dorset × Romanov sheep population,
Journal of Animal Science, 2006Co-Authors: B J Isler, B A Freking, R M Thallman, Michael P Heaton, Kreg A. LeymasterAbstract:There is concern about potential antagonistic correlated responses due to intensive selection for scrapie-resistant haplotypes of the prion (PRNP) gene in sheep. The objective of the present research was to test for associations of PRNP haplotypes for codons 136, 154, and 171 with growth, carcass, and meat quality traits in an F 2 Dorset x Romanov population (n = 415) segregating the 2 callipyge alleles. Haplotypes of the 3 PRNP codons were determined for each sheep, and breed of origin of each gamete was predicted by genotyping 6 microsatellite markers flanking the PRNP locus. Twenty-five growth, carcass, and meat quality traits were evaluated. Data were analyzed using a basic model consisting of fixed effects of year, sex, and callipyge genotype, the random effect of sire, and 7 covariates corresponding to the probability that a lamb inherited a specific PRNP haplotype of either Dorset or Romanov origin. A fixed effect of litter size was added to the model for growth traits. The model for carcass traits contained the linear and quadratic effects of chilled carcass weight and the interactions among callipyge genotype and linear and quadratic terms. For meat quality traits, the model contained chilled carcass weight as a covariate and the interaction between callipyge genotype and chilled carcass weight. A contrast between the resistant ARR haplotype and the average effect of other PRNP haplotypes was tested to investigate the effects of potential selection for ARR within each breed of origin (Dorset, ARR vs. ARQ, VRQ, and AHQ; Romanov, ARR vs. ARQ and VRQ). There was limited evidence that selecting for scrapie resistance would cause correlated responses due to linkage disequilibrium. Associations of only 3 traits with PRNP haplotypes were detected in either breed of origin. In Romanov, the ARR haplotype was associated with longer carcasses (P < 0.013), narrower rumps (P = 0.038), and less marbling (P = 0.022) than the average of ARQ and VRQ haplotypes. No significant contrasts were detected for Dorset. This study is the first to account for breed of origin while investigating haplotype associations in an F 2 population. This study provided limited evidence of associations between PRNP haplotypes and growth, carcass, and meat quality traits.
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evaluation of dorset finnsheep Romanov texel and montadale breeds of sheep iv survival growth and carcass traits of f1 lambs
Journal of Animal Science, 2004Co-Authors: B A Freking, K A LeymasterAbstract:Theobjectives ofthisstudywere toesti- mate effectsof sirebreed (Dorset,Finnsheep, Romanov, Texel, and Montadale), and dam breed (Composite III and Northwestern whiteface) on survival, growth, car- cass, and composition traits of F1 lambs. Effects of mat- ing season (August, October, and December) were esti- mated for survival and growth traits. Data were col- lected on 4,320 F1 lambs sired by 102 purebred rams over 3 yr. Birth weight was recorded on all lambs, and subsequent BW were adjusted to 56 (weaning), 70, and 140 d of age (n = 3,713, 3,654, and 3,579 observations, respectively). Survival of dam-reared progeny (n = 4,065) to weaning was recorded. Each year, wethers from October matings were slaughtered in three groups at 25, 29, and 33 wk of age to obtain carcass data (n = 546). In addition to standard carcass traits, resistive impedance measurements were recorded on the warm carcass to predict lean mass. Dam breed (P = 0.37) did not influence lamb survival to weaning, but sire breed (P <0.05)wasimportant.Romanov-siredlambsexcelled in survival rate to weaning (94.1%), followed by Finn- sheep(93.0%),Texel(90.7%),Dorset(90.0%),andMont- adale(89.1%) siredprogeny. Lower(P <0.01) postwean- ing growth rate was observed for Texel (267 g/d) and Finnsheep (272 g/d) sired progeny than for Dorset (285 g/d), Montadale (282 g/d), and Romanov (278 g/d) sired progeny. Sire breed and dam breed were generally sig- nificant for most carcass traits. Breed differences in distribution of carcass fat and carcass shape were de- tected; however, carcass composition was similar for all sire breeds when compared at a constant carcass weight. When evaluated at a constant 12th-rib fat depth, carcasses of lambs from Finnsheep, Romanov, and Texel sires produced 1 to 1.5 kg less (P < 0.001) predicted lean mass per lamb than carcasses of lambs from Dorset and Montadale sires. These experimental results provide information about the direct breed ef- fects for survival, growth, and carcass traits of these breeds and their potential use in crossbreeding systems.
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evaluation of dorset finnsheep Romanov texel and montadale breeds of sheep iii wool characteristics of f1 ewes
Journal of Animal Science, 2004Co-Authors: C J Lupton, B A Freking, K A LeymasterAbstract:: An experiment was designed to evaluate the effects of five sire breeds (Dorset, Finnsheep, Romanov, Texel, and Montadale), two dam breeds (Composite III [CIII] and northwestern whiteface [WF]), and three shearing seasons (December, February, and April, corresponding to August, October, and December breeding seasons) and their interactions on wool and other characteristics of F1 ewes. Fleeces were collected and characterized from six 2-yr-old F1 ewes representing each of the 90 sire breed x dam breed x shearing season x year (three) subclasses. Characteristics measured objectively were grease and clean fleece weights, clean yield, mean fiber diameter and SD, and mean staple length and SD. Visual assessments of fleece color were also made. Data collected on the F1 ewes were analyzed using a mixed model analysis of variance procedure. The model included fixed effects of year of birth, sire breed, dam breed, shearing season, six two-way interactions, and the three-way interaction of sire breed x dam breed x shearing season. The random effect of individual sire within year of birth x sire breed was also fitted. Texel- and Montadale-sired ewes produced more clean wool (P < 0.05) (approximately 0.24 kg) than Dorset-, Finnsheep-, and Romanov-sired ewes. Texel-sired ewes produced the coarsest wool (28.7 microm) (P < 0.05), whereas Romanov-sired ewes produced the finest (24.9 microm) and longest (9.12 cm) fleeces (P < 0.05). Ewes from WF dams produced more and finer wool (0.15 kg and 2.7 microm) than ewes from CIII dams (P < 0.001). Ewes shorn in December produced more, coarser, and longer wool (P < 0.05) than those shorn in February and April. This trend in wool production is opposite to that in conception rate (reported previously). Romanov-sired ewes produced the lowest percentage of white fleeces (62.6%), whereas Dorset-sired ewes produced the most (P < 0.001) white fleeces (96.3%). Estimates of heritability were calculated for grease and clean fleece weights (0.36), percentage of clean yield (0.31), average fiber diameter and SD (0.86 and 0.42, respectively), and average staple length and SD (0.49 and 0.00, respectively). Although necessary for a thorough evaluation of these 10 types of crossbred ewes, it is estimated that wool income would only constitute a small portion (1 to 5%) of overall income from sheep of this type.
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Evaluation of Dorset, Finnsheep, Romanov, Texel, and Montadale breeds of sheep: II. Reproduction of F 1 ewes in fall mating seasons
Journal of Animal Science, 2004Co-Authors: B A Freking, Kreg A. Leymaster, Eduardo CasasAbstract:Objectives were to estimate effects of sire breed (Dorset, Finnsheep, Romanov, Texel, and Montadale), dam breed (Composite III and northwestern whiteface), mating season (August, October, and December), ewe age (1, 2, and 3 yr), and their interactions on reproductive traits of F1 ewes. A total of 1,799 F1 ewes produced 3,849 litters from 4,804 exposures to Suffolk rams during 35-d mating seasons over 3 yr. Ewes were weighed at breeding. Conception rate and ewe longevity (present or absent at 42 mo of age) were determined. Number born and litter birth weight were recorded, and number and weight at weaning and 20 wk of age were analyzed separately for dam- and nursery-reared litter mates. Total productivity through 3 yr of age for each ewe entering the breeding flock was calculated as the sum of 20-wk weights for dam- or nursery-reared lambs. Interactions of sire breed x mating season, sire breed x ewe age, and mating season x ewe age were generally significant, whereas interactions of sire breed, mating season, and ewe age x dam breed were seldom detected. Interactions of sire breed x mating season were often due to changes in rank as well as magnitude, indicating the importance of matching sire breed to a specific mating season. The number born to Dorset-, Texel-, and Montadale-sired ewes was not affected by dam breed; however, Finnsheep-sired ewes out of northwestern whiteface dams were more prolific than Finnsheep-sired ewes out of Composite III dams, and the opposite situation existed for Romanov-sired ewes. Least squares means of sire breeds (P < 0.001) for total productivity of dam-reared lambs were 98.5, 103.5, 106.9, 124.6, and 154.9 kg/ewe entering the breeding flock for Texel, Dorset, Montadale, Finnsheep, and Romanov, respectively. Superior reproduction of Romanov-sired ewes was due to greater conception rate and prolificacy for each mating season and ewe age, as well as greater ewe longevity. Total productivity of F1 ewes by Composite III dams (125.6 kg) was greater (P < 0.001) than for ewes born to northwestern whiteface dams (109.7 kg), and the effect of mating season increased (P < 0.001) from August to October to December. Litter weight at 20 wk of age of 2- and 3-yr-old ewes was similar but greater (P < 0.001) than for 1-yr-old ewes. Experimental results provide comprehensive information about the appropriate use of these breeds in crossbreeding systems to meet specific production-marketing objectives.
L D Young - One of the best experts on this subject based on the ideXlab platform.
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evaluation of dorset finnsheep Romanov texel and montadale breeds of sheep i effects of ram breed on productivity of ewes of two crossbred populations
Journal of Animal Science, 2000Co-Authors: B A Freking, K A Leymaster, L D YoungAbstract:: Effects of Dorset, Finnsheep, Romanov, Texel, and Montadale breeds for performance as sires were estimated in the initial phase of a comprehensive evaluation of these breeds as contributors to sheep crossbreeding systems. Objectives were to evaluate the effects of ram breed, ewe breed, season of mating, and two-way interactions. Rams from the five breeds were single-sire-mated with ewes from two breed types to produce lambs over a 3-yr period. Ewes were assigned to one of three distinct 35-d mating seasons initiated each year in August, October, and December. A different sample of six rams per breed was used each year across all three seasons, and each ram was penned with ewes of both breeds. Traits evaluated and number of ewe records were conception rate and litter weaning weight per ewe exposed (n = 3,261) and number born, litter birth weight, average birth weight, number weaned, and litter weaning weight per ewe lambing (n = 2,751). Ram breed and ewe breed interacted (P < .01) for conception rate and litter weaning weight per ewe exposed, implicating mating preferences, particularly of Romanov rams. In mixed groups of ewes exposed to Romanov rams, conception rate was 12.7% lower and litter weight weaned was 8.4 kg lower in the ewe breed presumably less preferred for mating by the rams. On a per ewe exposed basis, Romanov-sired litters produced either the largest or the smallest values for litter weaning weight, depending on the breed of ewe. Effects of ram breed on number born and litter birth weight interacted (P < .05) with season of mating. The largest litters within each ram breed were associated with the October mating season. Montadale and Romanov rams sired larger and heavier litters from August matings than from December matings, whereas the opposite was true for Dorset-sired litters. Texel- and Finnsheep-sired litters were similar in size and weight from August and December matings. Breed of ram differences affected per ewe lambing productivity measurements (P < .01). Differences between ram breeds for ewe productivity were noted, with increased number born and improved survival of crossbred progeny to weaning for Romanov-sired litters. These results may have implications for using these ram breeds as sires in different crossbreeding systems. Structured mating systems or the creation of new composite populations involving these breeds could be used to match the resources, environment, and market of specific production situations.
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comparison of finnish landrace and Romanov as prolific breeds in a terminal sire crossbreeding system
Journal of Animal Science, 1993Co-Authors: C Gallivan, R A Kemp, Y M Berger, L D YoungAbstract:Targhee ewes lambing to Romanov vs Finnish Landrace rams gave birth to .22 more lambs ( P = .02) and had .15 more lambs alive at weaning ( P = .11) but did not rear more lambs. Finnish Landrace x Targhee (FT and Romanov x Targhee ( RT) lambs were similar for preweaning survival and for all growth and carcass traits studied. Romanov x Targhee ewes were 14.2 f 6.2 d younger (P = .02) at their first estrus and 12.1 f 2.8 d younger (P < .01) at their first lambing than FT ewes. The ovulation rate of RT ewes exceeded that of FT ewes by .35 ( P < .01). Romanov x Targhee ewes gave birth to .42 more ( P < .Ol) lambs per ewe lambing, had .39 more ( P < .01) lambs alive at weaning per ewe lambing, and reared .15 more (P = .03) lambs per ewe lambing than FT ewes. Embryonic survival, adjusted for ovulation rate, was greater (P < .01) for RT (88.3 k 3.3%) than for FT (80.0 k 3.7%) ewes. Lamb survival was similar for the two F1 crosses, with or without adjustment for number of lambs born. Overall survival (the proportion of ova that resulted in weaned lambs) was greater (P = .02) for RT ewes (77.6 k 4.2%) than for FT ewes (67.5 _+ 4.7%), at the same ovulation rate. When ewes were credited with all the lambs they gave birth to, RT ewes produced 4.6 k 1.8 kg more (P < .01) weight of lamb at weaning. When ewes were credited only for lambs they reared themselves, RT ewes weaned 3.8 f 2.0 kg more (P = .06) weight of lamb than FT ewes did. The postweaning survival and ADG of terminal offspring of FT and RT ewes were similar.
J M Elsen - One of the best experts on this subject based on the ideXlab platform.
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polygenic variation and transmission factors involved in the resistance susceptibility to scrapie in a Romanov flock
Journal of General Virology, 2005Co-Authors: C Diaz, Zulma G Vitezica, Rachel Rupp, Olivier Andreoletti, J M ElsenAbstract:Data from 4049 Romanov sheep belonging to a flock affected by natural scrapie were analysed by using survival-analysis techniques. Failure time was defined as the period of time between first exposure to infection and the date that animals left the flock with scrapie signs. Four hundred and forty-seven sheep were identified as 'scrapie animals'. Several models, including level of exposure as a time-dependent effect, PrP genotype, sex, age at first exposure, litter size and factors related to vertical transmission, were tested. The best model was extended to a sire-dam frailty model, in order to estimate the polygenic variation in addition to that in the Prnp gene. A combined effect of rearing type and the dam's disease status was detected. Thus, only sheep with a low degree of exposure to infection as lambs (lambs reared artificially and born out of a healthy dam) showed less risk than others. Animals first exposed to infection at older ages seemed to be less susceptible to scrapie. In this Romanov population, new genotypes (AHQ/AHQ, AHQ/VRQ, ARR/VRQ and ARR/ARQ) were associated with risk, suggesting the effect of genotypes on the incubation period of animals. Polygenic variance was responsible for 21 % of the total genetic variability that was related to susceptibility to scrapie. Therefore, the genetic susceptibility to scrapie may be explained by the joint effect of point mutations at the Prnp major gene and a number of genes that modulate its effect.
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Polygenic variation and transmission factors involved in the resistance/susceptibility to scrapie in a Romanov flock.
Journal of General Virology, 2005Co-Authors: C Diaz, Zulma G Vitezica, Rachel Rupp, Olivier Andreoletti, J M ElsenAbstract:Data from 4049 Romanov sheep belonging to a flock affected by natural scrapie were analysed by using survival-analysis techniques. Failure time was defined as the period of time between first exposure to infection and the date that animals left the flock with scrapie signs. Four hundred and forty-seven sheep were identified as 'scrapie animals'. Several models, including level of exposure as a time-dependent effect, PrP genotype, sex, age at first exposure, litter size and factors related to vertical transmission, were tested. The best model was extended to a sire-dam frailty model, in order to estimate the polygenic variation in addition to that in the Prnp gene. A combined effect of rearing type and the dam's disease status was detected. Thus, only sheep with a low degree of exposure to infection as lambs (lambs reared artificially and born out of a healthy dam) showed less risk than others. Animals first exposed to infection at older ages seemed to be less susceptible to scrapie. In this Romanov population, new genotypes (AHQ/AHQ, AHQ/VRQ, ARR/VRQ and ARR/ARQ) were associated with risk, suggesting the effect of genotypes on the incubation period of animals. Polygenic variance was responsible for 21 % of the total genetic variability that was related to susceptibility to scrapie. Therefore, the genetic susceptibility to scrapie may be explained by the joint effect of point mutations at the Prnp major gene and a number of genes that modulate its effect.
Marko Samardžija - One of the best experts on this subject based on the ideXlab platform.
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influence of season rainfall and air temperature on the reproductive efficiency in Romanov sheep in croatia
International Journal of Biometeorology, 2019Co-Authors: Dražen đuricic, Miroslav Benic, Ivona žura žaja, Hrvoje Valpotic, Marko SamardžijaAbstract:The aim of this study was to investigate the influence of season, rainfall and air temperature on the reproductive efficiency in the Romanov breed of sheep in continental part of Croatia during five consecutive years (2012–2016). During this period, 5379 matings resulted in 5046 successful conceptions, i.e. lambings at eight medium-scale Romanov breed sheep farms. The conception rate was 93.81%, fecundity was 195% and average preweaning mortality until 90 days of age was 12.41%. The seasonal distribution of lambings was 47.64% for ewes that delivered in winter (n = 2422), 23.37% in spring (n = 1179), 18.82% in summer (n = 950) and 9.81% in autumn (n = 495). Sexual activity was lowest during spring and early summer when air temperatures were above average (very and extremely warm), and sexual activity peaked from August to September, especially during extremely wet and very wet seasons. Litter size was greater during winter than in other seasons (1.70 vs. 1.54) and was significantly different as compared to each of selected years of the study period. There was a statistically significant difference in the number of pregnant ewes between mating seasons. Most female Romanov lambs born during winter and early spring mated in late summer or autumn and delivered at the age of 1 year or earlier. The seasonal distribution of matings and lambing was not uniform throughout the seasons over five consecutive years. Thus, it can be assumed that air temperature and rainfall during different seasons could affect the reproductive efficiency in Romanov breed of sheep in continental part of Croatia.
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seasonal lambing distribution of the Romanov breed in northwestern croatia during five consecutive years
Abstract book of the 30th World Buiatics Congress Sapporo Japan, 2018Co-Authors: Dražen đuricic, Ivona žura žaja, Hrvoje Valpotic, Romana Turk, Silvijo Vince, Juraj Grizelj, Branimira Spoljaric, Ivan Folnožic, Ivan Butkovic, Marko SamardžijaAbstract:Objectives. The aim of this study was to investigate the lambing distribution of the Romanov breed in northwestern Croatia during five consecutive years. Most European breeds of sheep are seasonal breeders in the moderate climate region ; however, the Romanov breed is a meat breed that is aseasonally polyoestrous. Romanov sheep are considered to be highly fertile, with a fecundity rate of 230% or more. In Croatia, the lambing season is primarily in the winter and spring for seasonal breeders. Materials and methods. During five consecutive years (December 2011 to November 2016) at eight medium-scale sheep farms in northwestern Croatia, there were 5379 mattings with 5046 successful conceptions i.e. lambings. Ewes were kept at pasture, which primarily provided area for exercise, with access to stables during the night, in a semi-intensive environment. According to standard farming practices, animals had free access to good quality meadow hay (about 1.8 kg per doe daily), adequate concentrate and drinking water. Results. Fertility was 93.81%. The seasonal distribution of lambings in this study was: 47.64% of ewes delivered in winter (n=2422), 23.37% in spring (n=1179), 18.82% in summer (n=950) and 9.81% in autumn (n=495). The winter season refers to the period of December to February. Sexual activity was lowest was during spring and early summer (March to June) with a peak of sexual activity from August to October. Litter size was greater during spring and winter than in other seasons (1.67 vs.1.36) though birth weight was lower in larger than in smaller litters (2.64±0.65 vs. 2.87±0.61). Conclusions. More lambs during lambing season and a higher percentage of multiple births (triplets, quadruplets, etc.) was expected during the optimal breeding season, as seen in most European sheep breeds. Despite being aseasonally polyoestrous, the distribution of mating and lambing was not uniform through the seasons for the Romanov breed.
