Economic selection index development for Beefmaster cattle I: Terminal breeding objective1

Ochsner, Kathleen P; MacNeil, M. D.; Lewis, Ronald M.; Spangler, Matthew L

doi:10.2527/jas.2016.1231

Cited by 12 publications

(8 citation statements)

References 23 publications

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“…Results from the present study clearly demonstrate that the terminal index used in Ireland is enabling the selection of more feed efficient cattle that yield heavier carcasses of better quality; this terminal index is similar to other terminal indexes used globally ( Amer et al, 1998 ; Ochsner et al, 2017 ). The results from the present study regarding the relationship between terminal index genetic merit and feed efficiency also corroborate those of Clarke et al (2009) , based on a relatively small controlled experiment study of 107 animals divergent for a previous Irish terminal index.…”

Section: Discussionsupporting

confidence: 73%

Feed and production efficiency of young crossbred beef cattle stratified on a terminal total merit index1

Kelly

Conroy

Murphy

et al. 2020

Translational Animal Science

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Abstract Few studies have attempted to quantify the association between a terminal total merit index with phenotypic feed and production efficiency in beef cattle, particularly when feed efficiency is itself explicitly absent as a goal trait in the index. The objective of the present study was to quantify the differences in phenotypic performance for feed intake, feed efficiency and carcass traits of crossbred bulls, steers and heifers differing in a terminal total merit index. A validation population of 614 bulls, steers and heifers that were evaluated for feed intake and efficiency in the same feedlot and subsequently slaughtered at the end of their test period was constructed. The Irish national genetic evaluations for a terminal index of calving performance, docility, feed intake and carcass traits were undertaken with the phenotypic records of animals present in the validation population masked. The validation population animals were subsequently stratified into four groups, within sex, according to their terminal index value. Mixed models were used to quantify the association between terminal genetic merit and phenotypic performance; whether the associations differed by sex was also investigated. The regression coefficient of phenotypic feed intake, carcass weight, carcass conformation or carcass fat on its respective estimated breeding values was 0.86 kg DM/d, 0.91 kg, 1.01 units and 1.29 units, respectively, which is close to the expectation of one. On average, cattle in the very high terminal index stratum had a 0.63 kg DM/d lower feed intake, a 25.05 kg heaver carcass, a 1.82 unit better carcass conformation (scale 1 to 15) and a 1.24 unit less carcass fat score (scale 1 to 15), relative to cattle in the very low terminal index stratum. Cattle of superior total genetic merit were also more feed efficient (i.e., had a lower energy conversion ratio, lower residual feed intake and greater residual gain), had a greater proportion of their live-weight as carcass weight (i.e., better dressing percentage) and were slaughtered at a younger age relative to their inferior total genetic merit counterparts. This study provides validation of an all-encompassing total merit index and demonstrates the benefits of selection on a total merit index for feed and production efficiency, which should impart confidence among stakeholders in the contribution of genetic selection to simultaneous improvements in individual animal performance and efficiency.

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Section: Discussionsupporting

confidence: 73%

Feed and production efficiency of young crossbred beef cattle stratified on a terminal total merit index1

Kelly

Conroy

Murphy

et al. 2020

Translational Animal Science

View full text Add to dashboard Cite

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“…Furthermore, an index that included MW derived by Barron Lopez (2013) had a negative MW index coefficient. Interestingly, the rank correlation between a terminal index for Beefmaster cattle reported by Ochsner et al (2017) and the index reported herein was 0.446, suggesting a need to clearly delineate breeding objectives given the differences in traits included in these 2 indices.…”

Section: Index Coefficientsmentioning

confidence: 94%

“…Economic values for the objective traits were derived using methods as described by Ochsner et al (2017). There were 3 traits considered that would routinely be recorded on a categorical scale: CDd, CDm, and HP.…”

Section: Estimation Of Economic Valuesmentioning

confidence: 99%

Economic selection index development for Beefmaster cattle II: General-purpose breeding objective

Ochsner¹,

MacNeil²,

Lewis³

et al. 2017

Journal of Animal Science

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“…Ochsner et al [44, 45] outlined procedures on how to develop a maternal economic selection index ($M) given EPD information. These procedures were followed based on selection objective weightings described by MacNeil [46].…”

Section: Methodsmentioning

confidence: 99%

Management of lethal recessive alleles in beef cattle through the use of mate selection software

et al. 2019

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Background Recessive loss-of-function (LOF) alleles at genes which are essential for life, can result in early embryonic mortality. Cattle producers can use the LOF carrier status of individual animals to make selection and mate allocation decisions. Methods Two beef cattle breeding strategies i.e. (1) selection against LOF carriers as parents and (2) simultaneous selection and mate allocation to avoid the occurrence of homozygous offspring in three scenarios, which differed in number and frequency of LOF alleles were evaluated using the mate selection program, MateSel. Scenarios included (a) seven loci with high-frequency LOF alleles, (b) 76 loci with low-frequency LOF alleles, and (c) 50 loci with random high- and low-frequency LOF alleles. In addition, any savings resulting from the information obtained by varying the percentage (0–100%) of the herd genotyped, together with segregation analysis to cover ungenotyped animals, were calculated to determine (1) which percentage optimized net profit for a fixed cost of genotyping ($30/test), and (2) the breakeven cost for genotyping. Results With full knowledge of the LOF alleles carried by selection candidates, the most profitable breeding strategy was always simultaneous selection and mate allocation to avoid homozygous affected offspring ( aa ) as compared to indiscriminate selection against carrier parents ( Aa ). The breakeven value of genotyping depended on the number of loci modeled, the LOF allele frequencies, and the mating/selection strategies used. Genotyping was most valuable when it was used to avoid otherwise high levels of embryonic mortalities. As the number of essential loci with LOF alleles increased, especially when some were present at relatively high minor allele frequencies, embryonic losses increased, and profit was maximized by genotyping 10 to 20% of a herd and using that information to reduce these losses. Conclusions Genotyping 100% of the herd was never the most profitable outcome in any scenario; however, genotyping some proportion of the herd, together with segregation analysis to cover ungenotyped animals, maximized overall profit in scenarios with large numbers of loci with LOF alleles. As more LOF alleles are identified, such a mate selection software will likely be required to optimally select and allocate matings to balance the rate of genetic gain, embryonic losses, and inbreeding.

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Economic selection index development for Beefmaster cattle I: Terminal breeding objective1

Cited by 12 publications

References 23 publications

Feed and production efficiency of young crossbred beef cattle stratified on a terminal total merit index1

Feed and production efficiency of young crossbred beef cattle stratified on a terminal total merit index1

Economic selection index development for Beefmaster cattle II: General-purpose breeding objective

Management of lethal recessive alleles in beef cattle through the use of mate selection software

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