The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
B. Watt - One of the best experts on this subject based on the ideXlab platform.
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High Merino weaner survival rates are a function of Weaning Weight and positive post-Weaning growth rates
Animal Production Science, 2010Co-Authors: S. Hatcher, J. Eppleston, K. J. Thornberry, B. WattAbstract:Survival and subsequent productivity of Merino ewe weaners (weaned in 2006 and 2007, respectively) on commercial properties in the New South Wales Central Tablelands were monitored through routine liveWeight measurement until Weaning of their own progeny from their maiden joining. Growth rates were calculated from the regular liveWeight measurements with survival determined by the continuing presence of an individual animal at subsequent measurements. This study demonstrates that high weaner survival rates are a function of both Weaning Weight and post-Weaning growth rates. Importantly, it indicates that low post-Weaning growth rates can negate the survival benefit conferred by a high Weaning Weight such that weaners who were unable to sustain positive post-Weaning growth rates were at high risk of death. Furthermore, classification of weaners into liveWeight profile groups based on their Weaning Weight and post-Weaning growth rates identified another group of weaners that are also at high risk of death. These weaners (14% of the mob) had above average Weaning Weights but low post-Weaning growth rates and a mortality rate nearly 1.5 times that of the lightest cohort of weaners. High weaner survival rates about the 95% industry benchmark are possible if weaners show positive growth rates post Weaning. Weaning Weight continues to have a residual influence on the subsequent productivity of ewe weaners until they wean their first lambs. Maiden ewes that were heavier at Weaning tend to have higher scanning percentages and are more likely to successfully rear their progeny to marking than their lighter Weight counterparts. This finding should be taken into account when economic analyses of the benefits of alternative management strategies to promote weaner survival are undertaken.
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Higher Weaning Weight improves postWeaning growth and survival in young Merino sheep
Australian Journal of Experimental Agriculture, 2008Co-Authors: S. Hatcher, J. Eppleston, R. P. Graham, J. Mcdonald, S. Schlunke, B. Watt, K. J. ThornberryAbstract:Two monitoring projects were conducted to investigate weaner mortality in commercial Merino flocks in the Yass and the Central Tablelands Rural Lands Protection Boards located in the Southern Tablelands agricultural region of New South Wales. The projects were conducted in Yass in 2005 and in the Central Tablelands in 2006. A random sample of weaners from four flocks in the Yass board and 11 flocks in the Central Tablelands board were regularly weighed, growth rates were calculated after Weaning and survival was determined by the continuing presence of an individual weaner at subsequent weighing activities. Weaning Weight was the most important factor in determining postWeaning liveWeight, growth rates and survival with the significant impact of Weaning Weight on liveWeight persisting for up to 6 months after Weaning. Despite the lightest weaners being capable of considerable compensatory growth given sufficient postWeaning nutrition, the lightest 25% of weaners were more than twice as likely to die as heavier weaners. A focus on ewe nutrition and parasite control during late pregnancy and lactation will allow Merino producers to achieve higher Weaning Weights that will set their weaners up for strong postWeaning growth with a decreased likelihood of mortality.
S. Hatcher - One of the best experts on this subject based on the ideXlab platform.
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High Merino weaner survival rates are a function of Weaning Weight and positive post-Weaning growth rates
Animal Production Science, 2010Co-Authors: S. Hatcher, J. Eppleston, K. J. Thornberry, B. WattAbstract:Survival and subsequent productivity of Merino ewe weaners (weaned in 2006 and 2007, respectively) on commercial properties in the New South Wales Central Tablelands were monitored through routine liveWeight measurement until Weaning of their own progeny from their maiden joining. Growth rates were calculated from the regular liveWeight measurements with survival determined by the continuing presence of an individual animal at subsequent measurements. This study demonstrates that high weaner survival rates are a function of both Weaning Weight and post-Weaning growth rates. Importantly, it indicates that low post-Weaning growth rates can negate the survival benefit conferred by a high Weaning Weight such that weaners who were unable to sustain positive post-Weaning growth rates were at high risk of death. Furthermore, classification of weaners into liveWeight profile groups based on their Weaning Weight and post-Weaning growth rates identified another group of weaners that are also at high risk of death. These weaners (14% of the mob) had above average Weaning Weights but low post-Weaning growth rates and a mortality rate nearly 1.5 times that of the lightest cohort of weaners. High weaner survival rates about the 95% industry benchmark are possible if weaners show positive growth rates post Weaning. Weaning Weight continues to have a residual influence on the subsequent productivity of ewe weaners until they wean their first lambs. Maiden ewes that were heavier at Weaning tend to have higher scanning percentages and are more likely to successfully rear their progeny to marking than their lighter Weight counterparts. This finding should be taken into account when economic analyses of the benefits of alternative management strategies to promote weaner survival are undertaken.
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Higher Weaning Weight improves postWeaning growth and survival in young Merino sheep
Australian Journal of Experimental Agriculture, 2008Co-Authors: S. Hatcher, J. Eppleston, R. P. Graham, J. Mcdonald, S. Schlunke, B. Watt, K. J. ThornberryAbstract:Two monitoring projects were conducted to investigate weaner mortality in commercial Merino flocks in the Yass and the Central Tablelands Rural Lands Protection Boards located in the Southern Tablelands agricultural region of New South Wales. The projects were conducted in Yass in 2005 and in the Central Tablelands in 2006. A random sample of weaners from four flocks in the Yass board and 11 flocks in the Central Tablelands board were regularly weighed, growth rates were calculated after Weaning and survival was determined by the continuing presence of an individual weaner at subsequent weighing activities. Weaning Weight was the most important factor in determining postWeaning liveWeight, growth rates and survival with the significant impact of Weaning Weight on liveWeight persisting for up to 6 months after Weaning. Despite the lightest weaners being capable of considerable compensatory growth given sufficient postWeaning nutrition, the lightest 25% of weaners were more than twice as likely to die as heavier weaners. A focus on ewe nutrition and parasite control during late pregnancy and lactation will allow Merino producers to achieve higher Weaning Weights that will set their weaners up for strong postWeaning growth with a decreased likelihood of mortality.
K. J. Thornberry - One of the best experts on this subject based on the ideXlab platform.
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High Merino weaner survival rates are a function of Weaning Weight and positive post-Weaning growth rates
Animal Production Science, 2010Co-Authors: S. Hatcher, J. Eppleston, K. J. Thornberry, B. WattAbstract:Survival and subsequent productivity of Merino ewe weaners (weaned in 2006 and 2007, respectively) on commercial properties in the New South Wales Central Tablelands were monitored through routine liveWeight measurement until Weaning of their own progeny from their maiden joining. Growth rates were calculated from the regular liveWeight measurements with survival determined by the continuing presence of an individual animal at subsequent measurements. This study demonstrates that high weaner survival rates are a function of both Weaning Weight and post-Weaning growth rates. Importantly, it indicates that low post-Weaning growth rates can negate the survival benefit conferred by a high Weaning Weight such that weaners who were unable to sustain positive post-Weaning growth rates were at high risk of death. Furthermore, classification of weaners into liveWeight profile groups based on their Weaning Weight and post-Weaning growth rates identified another group of weaners that are also at high risk of death. These weaners (14% of the mob) had above average Weaning Weights but low post-Weaning growth rates and a mortality rate nearly 1.5 times that of the lightest cohort of weaners. High weaner survival rates about the 95% industry benchmark are possible if weaners show positive growth rates post Weaning. Weaning Weight continues to have a residual influence on the subsequent productivity of ewe weaners until they wean their first lambs. Maiden ewes that were heavier at Weaning tend to have higher scanning percentages and are more likely to successfully rear their progeny to marking than their lighter Weight counterparts. This finding should be taken into account when economic analyses of the benefits of alternative management strategies to promote weaner survival are undertaken.
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Higher Weaning Weight improves postWeaning growth and survival in young Merino sheep
Australian Journal of Experimental Agriculture, 2008Co-Authors: S. Hatcher, J. Eppleston, R. P. Graham, J. Mcdonald, S. Schlunke, B. Watt, K. J. ThornberryAbstract:Two monitoring projects were conducted to investigate weaner mortality in commercial Merino flocks in the Yass and the Central Tablelands Rural Lands Protection Boards located in the Southern Tablelands agricultural region of New South Wales. The projects were conducted in Yass in 2005 and in the Central Tablelands in 2006. A random sample of weaners from four flocks in the Yass board and 11 flocks in the Central Tablelands board were regularly weighed, growth rates were calculated after Weaning and survival was determined by the continuing presence of an individual weaner at subsequent weighing activities. Weaning Weight was the most important factor in determining postWeaning liveWeight, growth rates and survival with the significant impact of Weaning Weight on liveWeight persisting for up to 6 months after Weaning. Despite the lightest weaners being capable of considerable compensatory growth given sufficient postWeaning nutrition, the lightest 25% of weaners were more than twice as likely to die as heavier weaners. A focus on ewe nutrition and parasite control during late pregnancy and lactation will allow Merino producers to achieve higher Weaning Weights that will set their weaners up for strong postWeaning growth with a decreased likelihood of mortality.
J. Eppleston - One of the best experts on this subject based on the ideXlab platform.
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High Merino weaner survival rates are a function of Weaning Weight and positive post-Weaning growth rates
Animal Production Science, 2010Co-Authors: S. Hatcher, J. Eppleston, K. J. Thornberry, B. WattAbstract:Survival and subsequent productivity of Merino ewe weaners (weaned in 2006 and 2007, respectively) on commercial properties in the New South Wales Central Tablelands were monitored through routine liveWeight measurement until Weaning of their own progeny from their maiden joining. Growth rates were calculated from the regular liveWeight measurements with survival determined by the continuing presence of an individual animal at subsequent measurements. This study demonstrates that high weaner survival rates are a function of both Weaning Weight and post-Weaning growth rates. Importantly, it indicates that low post-Weaning growth rates can negate the survival benefit conferred by a high Weaning Weight such that weaners who were unable to sustain positive post-Weaning growth rates were at high risk of death. Furthermore, classification of weaners into liveWeight profile groups based on their Weaning Weight and post-Weaning growth rates identified another group of weaners that are also at high risk of death. These weaners (14% of the mob) had above average Weaning Weights but low post-Weaning growth rates and a mortality rate nearly 1.5 times that of the lightest cohort of weaners. High weaner survival rates about the 95% industry benchmark are possible if weaners show positive growth rates post Weaning. Weaning Weight continues to have a residual influence on the subsequent productivity of ewe weaners until they wean their first lambs. Maiden ewes that were heavier at Weaning tend to have higher scanning percentages and are more likely to successfully rear their progeny to marking than their lighter Weight counterparts. This finding should be taken into account when economic analyses of the benefits of alternative management strategies to promote weaner survival are undertaken.
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Higher Weaning Weight improves postWeaning growth and survival in young Merino sheep
Australian Journal of Experimental Agriculture, 2008Co-Authors: S. Hatcher, J. Eppleston, R. P. Graham, J. Mcdonald, S. Schlunke, B. Watt, K. J. ThornberryAbstract:Two monitoring projects were conducted to investigate weaner mortality in commercial Merino flocks in the Yass and the Central Tablelands Rural Lands Protection Boards located in the Southern Tablelands agricultural region of New South Wales. The projects were conducted in Yass in 2005 and in the Central Tablelands in 2006. A random sample of weaners from four flocks in the Yass board and 11 flocks in the Central Tablelands board were regularly weighed, growth rates were calculated after Weaning and survival was determined by the continuing presence of an individual weaner at subsequent weighing activities. Weaning Weight was the most important factor in determining postWeaning liveWeight, growth rates and survival with the significant impact of Weaning Weight on liveWeight persisting for up to 6 months after Weaning. Despite the lightest weaners being capable of considerable compensatory growth given sufficient postWeaning nutrition, the lightest 25% of weaners were more than twice as likely to die as heavier weaners. A focus on ewe nutrition and parasite control during late pregnancy and lactation will allow Merino producers to achieve higher Weaning Weights that will set their weaners up for strong postWeaning growth with a decreased likelihood of mortality.
E. J. Pollak - One of the best experts on this subject based on the ideXlab platform.
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Estimation of genetic variance and covariance components for Weaning Weight in Simmental cattle
Journal of animal science, 1997Co-Authors: Chaeyoung Lee, C.p. Van Tassell, E. J. PollakAbstract:The objectives of this study were to estimate genetic parameters for Weaning Weight of Simmental cattle from data without selective reporting and to examine heterogeneity of parameters with a multiple trait approach. Heterogeneity of (co)variance components (VC) by sex is accounted for in national genetic evaluations for Simmental cattle. Completely reported data were split into bull, heifer, and steer populations to obtain VC estimates. Estimates of direct-maternal genetic correlation were negative, which suggests that selective reporting was not a cause of a negative correlation in Simmental data. However, analyzing only data for males does not account for selection on females and vice versa. Heterogeneous VC for sex were evaluated by analyzing Simmental data using a multiple trait model where male and female data were treated as two traits. Estimates of heritability of direct (maternal) effects were .19 (.07) and .25 (.12) and estimates of the direct-maternal genetic correlation were -.05 and -.20 for males and females, respectively. The multiple trait model fit the data better (P < .01) than the model under the assumption of homogeneous VC.
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relationship between sire x year interactions and direct maternal genetic correlation for Weaning Weight of simmental cattle
Journal of Animal Science, 1997Co-Authors: Chaeyoung Lee, E. J. PollakAbstract:The interrelation of sire x year interactions (SY) and direct-maternal genetic correlation (r dm ) for Weaning Weight was examined for bias in estimating r dm . Weaning Weight records were simulated using models containing SY (D1), r dm (D2), or both (D3). When D1 data were analyzed ignoring SY, a nonzero r dm was observed, and direct and maternal genetic variance estimates were inflated. Analysis of D2 data ignoring r dm did not reveal a spurious SY, and direct and maternal genetic variance estimates were deflated. On application to Weaning Weights of Simmental cattle, the model ignoring SY resulted in a direct-maternal genetic correlation estimate of -.29. The model using both SY and r dm fit the data better ( P <.01). The SY variance represented only 3% of phenotypic variance but explained 62% of the covariance between direct and maternal genetic effects estimated ignoring SY. However, a negative estimate of the genetic correlation (-.14) was still obtained.
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influence of partitioning data by sex on genetic variance and covariance components for Weaning Weight in beef cattle
Journal of Animal Science, 1997Co-Authors: Chaeyoung Lee, E. J. PollakAbstract:Heterogeneity of (co)variance components (VC) by sex is currently accounted for in national genetic evaluations for Simmental cattle. Parameters used in the national evaluation program are estimated from data split into male, female, and steer populations. Analyzing only male data does not account for selection on females, and vice versa. To determine the impact of selection, a Monte Carlo simulation was used, and estimates of VC for Weaning Weight were obtained when data were partitioned by sex. Weaning Weight data were simulated using homogeneous VC for males and females for random and selected populations. Restricted maximum likelihood estimates were obtained for direct and maternal genetic and permanent and temporary environmental variances and genetic covariance between direct and maternal effects by analyzing complete or split data. Estimates differed (P <.01) from input values in data from selected populations split by sex, yielding a spurious heterogeneity of VC for sex. The heterogeneity was reduced in models using genetic groups but not completely removed. Splitting data by sex also influenced VC estimates in data simulated with heterogeneous VC for males and females.
