The American Angus Association has sponsored a carcass evaluation since 1974. The carcass data collected as a part of this program are used by the association to conduct a biannual sire evaluation for carcass merit. This paper presents age-adjustment factors and genetic parameter estimates for carcass traits to be used in the Angus carcass genetic evaluation program. Because of the large range in slaughter ages, age classes were defined as all those animals slaughtered at an age of < or = 480 d and those with a slaughter age > 480 d. Linear and quadratic partial regressions on slaughter age for hot carcass weight (HCW), USDA marbling score (MS), 12th rib longissimus muscle area (LMA), and 12th-rib fat thickness (FT) were estimated within sex and age class. Quadratic age regressions were not significant, nor was the linear age regression coefficient for FT in steers in the > 480-d age class. Heritability estimates for age-constant HCW, MS, LMA, and FT were .31, .26, .32, and .26, respectively. The estimated genetic correlation (rg) between HCW and LMA was .47. The estimated rg between HCW and FT was .38 and between MS and FT was -.13. The linear genetic trends for CWT and LMA were significantly positive at .414 kg/yr and .075 cm2/yr, respectively. The genetic trends for FT and MS were very small but significantly negative at -.004 cm/yr and -.003 units/yr, respectively.
Summary Genetic parameters were estimated for repeated racing times on Thoroughbred horses for several racing distances both on turf and dirt. An additive genetic and permanent environmental model of multiple‐trait derivative‐free restricted maximum likelihood (MTDFREML) was used. The data used were collected by the Japan Racing Association from 1986 to 1990 and the effects of individual race, sex, age, jockey and weight carried were used. The generation 2 pedigree information was preferable for variance estimates. Heritability decreases as the racing distance increases. These values were 0.25, 0.16, 0.10, 0.12, 0.09 and 0.08 at 1000, 1200, 1400, 1600, 1800, and 2000 m, respectively, on turf, and 0.19, 0.22, 0.12, 0.09 and 0.17 at 1000, 1200, 1400, 1600, and 1800 m, respectively, on dirt track. The values of repeatability were from 0.43 to 0.70 on turf, and from 0.51 to 0.67 on dirt track. These suggest that racing times at the different racing distances may be regarded as different traits when the horse is to be evaluated genetically. Zusammenfassung Schätzung genetischer Parameter für Rennzeit von japanischen Vollblütern durcb eingeschrïhte max‐imale Wahrscheinlichkeit Die Schätzung der genetischen Parameter erfolgte für wiederholte Rennzeiten von Vollblütern über mehrere Renndistanzen sowohl auf Rasen als auch auf Sandbahn. Zusätzlich wurde ein Permanent‐Umweltmodell (multiple‐trait derivative‐free restricted maximum likelihood (MTDFREML)) angewendet. Die Daten wurden von 1986 bis 1990 von JRA erhoben und die Wirkungen von Rasse, Geschlecht, Alter, Jockey und Tragegewicht geschätzt. Stammbaumdaten der Generation 2 dienten bevorzugt zur Varianzschätzung. Der Einfluß des Erbguts nimmt mit zunehmender Renndistanz ab, die betraffender h2 Werte waren 0,25, 0,16, 0,10, 0,12, 0,09 und 0,08 bei 1000, 1200, 1400, 1600, 1800 und 2000 m auf Rasen sowie 0,19, 0,22, 0,12, 0,09 und 0,17 bei 1000, 1200, 1400, 1600 und 1800 m auf Sandbahn. Der Wiederholbarkeitskoeffizient lag zwischen 0,43 und 0,70 auf Rasen und 0,51 bis 0,67 auf Sandbahn. Dies legt die Vermutung nahe, daß bei Zuchtwertschätzung Rennzeiten über verschiedene Distanzen als unterschiedliche Merkmale betrachtet werden sollen. Résumé Estimation des paramètres génétiques sur le temps de course chez les Pur‐sang au Japon, selon la méthode de probabilité maximum restreinte On a estimé les paramètres génétiques pour les temps de course répétés chez les chevaux Pur‐sang pour plusieurs distances de course sur gazon et sur terre battue. On a utilisé un modèle additif génétique et environnementiel permanent de vraisemblence maximum restreinte à traits multiples et sans dérivé (MTDFREML: ‘multiple‐trait derivative‐free restricted maximum likelihood’). Les données utilisées ont été rassemblées par la JRA de 1986 à 1990 et on a utilisé les effets de la race, du sexe, de l'âge, du jockey et de la charge portée. L'information de pédigrée de génération 2 s'est avérée préférable pour les estimations de variance. L'effet de l'hérédité diminue avec l'augmentation de la distance pa...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.