Genetic evaluation of the Texel breed in Uruguay: Carcass and Meat quality traits Ciappesoni G.; San Julián R.; Navajas E. A.; Gimeno D.; Gutierrez-Zamit E.; Goldberg V.; Brito G. August 21st, 2014. Punta del Este, Uruguay. 1 Introduction • Increased consumer´s emphasis on meat quality more interest on meat quality traits possibility for implementing into breeding programmes • In sheep, very few studies have reported genetic parameters for lamb carcass and meat quality traits. • These difficult-to-measure traits have received less attention despite their economic relevance. 2 Genetic Evaluation of Texel breed in Uruguay Central Progeny Testing (CPT) • Relevance of growth, carcass and meat quality traits as breeding objectives of Texel as sire terminal breed in Uruguay. • Genetic evaluation system (GES) since 2008 BW (optional), WW, SWT, REA, FT • CPT was established in the stud-flock “La Aripuca” located in Cerro Largo, 300 km north-east of Montevideo . • Goals: - to facilitate genetic linkage between studs-flocks - to allow genetic evaluation of carcass and meat quality traits 3 Objective To obtain estimations of genetic parameters and breeding values for in vivo and post-mortem carcass and meat quality traits of Texel breed raised on grazing conditions. 4 Material and Methods Data • Carcass and meat quality data: 424 female and male lambs from CPT, slaughtered between 2009-2013 (average 38.9 kg LW and 3.5 BCS). Pedigree data: 982 animals (23 sires and 318 dams). • In vivo carcass traits: 3109 records from 9 stud-flocks, pedigree data included 3.109 animals (56 sires and 1.825 dams). 5 Traits measured In vivo carcass traits • Scanning weight (SWT, kg) • Rib Eye Area (REA, cm2) • Fat Thickness (FT, mm) Routinely evaluated in the GES (average age of 255 days) 6 Traits measured Post-mortem traits • Hot Carcass weight (HCW, kg) • Tissue depht (GR, mm) • Weights of the most valuable cuts: - French Rack (Rack, g), - Shoulder with bone (Shoulder, g) - boneless Leg (Leg, g) • Morphometrics traits: - Carcass length (CL, cm) - Leg length (LL,cm) - Leg circumference (LC, cm) • Meat colour: parameters L* (relative lightness), a* (relative redness) and b* (relative yellowness) • Tenderness: Warner Brazler Shear Force (WBSF, KgF) • Intramuscular Fat Content (IMF, %) • Fatty acid profile: percentage of saturated (SFA,%), monounsaturated (MUFA,%) and polyunsaturated (PUFA, %) fatty acids. 7 Statistical analysis • Heritabilities (h2) were estimated by univariate analysis performed with the GIBBS2F90 computer package . • Multivariate analysis for in vivo traits. • Fixed effects: year-flock, birth type, sex, dam age and age at slaughter (covariate) • Estimated Progeny Differences (EPD) were estimated using BLUPF90 software. • Correlations between EPDs of the different traits for lambs with post-mortem records (n=424) were calculated. • Associations between main EPDs of rams used in the CPT (n=23) were plotted. 8 Results I Descriptive statistics for in vivo and post-mortem carcass traits. Trait n mean sd min max Scanning age (days) 3109 259 27 182 316 SWT (kg) 3094 35.52 7.79 16.80 75.00 REA (cm2) 3081 9.6 2.9 3.0 24.7 FT (mm) 3071 2.5 1.0 1.0 10.5 Slaughter age (days) 424 292 1.9 265 328 HCW (kg) 421 18.02 3.83 9.6 30 Rack (g) 420 889 230 395 1488 Leg (g) 421 3605 978 1760 6176 Shoulder (g) 419 3433 812 1445 5688 CL (cm) 422 63.5 5.0 51.0 75.0 LL (cm) 422 43.5 11.6 33.0 71.0 LC (cm) 421 56.4 10.4 35.0 72.0 GR (mm) 420 5.2 3.6 0.0 18.0 9 Results II Descriptive statistics for meat quality traits Trait n mean sd min max L* 394 36.93 3.52 26.39 45.17 a* 394 17.83 2.50 11.4 33.32 b* 394 6.86 2.24 2.87 14.49 WBSF (KgF) 388 4.20 1.23 1.92 7.86 IMF (%) 389 2.8 0.98 0.65 6.59 SFA (%) 385 45.6 3.7 33.8 56.8 MUFA (%) 385 41.7 3.1 29.0 50.0 PUFA (%) 383 12.7 4.0 5.4 33.3 10 Results III in vivo carcass traits Heritabilities (on diagonal) and genetic correlations (upper diagonal) (posterior standard deviation) for in vivo carcass traits. Trait SWT (kg) REA (cm2) FT (mm) SWT (kg) REA (cm2) FT (mm) 0.33 (0.06) 0.55 (0.12) 0.54 (0.12) 0.19 (0.05) 0.56 (0.13) 0.38 (0.07) In vivo carcass traits routinely recorded showed moderate h2 values and high genetic correlations between them. 11 Results IV post-mortem carcass traits Heritability estimates for post-mortem carcass traits. Trait Median PSD HCW (kg) 0.48 0.18 Rack (g) 0.71 0.16 Leg (g) 0.34 0.16 Shoulder (g) 0.39 0.15 CL (cm) 0.39 0.17 LL (cm) 0.51 0.17 LC (cm) 0.26 0.16 GR (mm) 0.27 0.14 Post-mortem carcass quality traits in Texel sheep in Uruguay have moderate to high h2 values, indicating there is scope for genetic improvement in these traits. PSD: posterior standard deviation These preliminary values should be interpreted with caution because of the small number of animals recorded. 12 Results V Meat quality traits Heritability estimates for meat quality traits. Trait Median PSD L* 0.21 0.12 a* 0.12 0.11 b* 0.19 0.15 WBSF (KgF) 0.19 0.13 IMF (%) 0.19 0.13 SFA (%) 0.27 0.17 MUFA (%) 0.15 0.14 PUFA (%) 0.19 0.13 Estimates of h2 for meat quality traits were low to moderate (0.12 to 0.27). PSD: posterior standard deviation Reports of h2 of fatty acid profiles are very scarce, particularly in lamb meat. 1313 Results VI post-mortem carcass traits Pearson correlation coefficients between EPDs of animals with post-mortem records (n=424). Trait SWT (kg) REA (cm2) FT (mm) HCW (kg) CL (cm) LC (cm) REA (cm2) 0.46 - - - - - FT (mm) 0.53 0.46 - - - - HCW (kg) 0.63 0.54 0.28 - - - CL (cm) 0.59 0.33 0.24 0.59 - - LL (cm) 0.53 0.31 0.20 0.54 0.45 - LC (cm) 0.54 0.42 0.13 0.73 0.59 - Rack (g) 0.52 0.50 0.25 0.77 0.52 0.70 Leg (g) 0.53 0.45 NS 0.80 0.56 0.83 Shoulder (g) 0.67 0.49 0.28 0.81 0.67 0.77 GR (cm) 0.27 0.32 0.36 0.41 0.24 0.23 NS: correlation non-statistically different form zero (p>0.01). 1414 •All correlations between EPDs were positive and favourable. •The exception could be the correlations with fatness traits (FT and GR), depending on the selection objective. •Increasing SWT and REA by selection will cause a correlated increase in FT and GR, that could be favourable, neutral or unfavourable depending on the current phenotypic levels of carcass fat of pure and crossbreed lambs, as well as the production system and market specifications. •The HCW EPD presented high correlation coefficients with valuable cuts EPDs (Rack, Shoulder and Leg). • Cuts weights also presented high correlations with REA EPD. 15 Associations between EPDs of the main traits for rams used in the CPT (n=23). Figure 1. Association between ram HCW EPD and scanning weight (SWT) EPD. Figure 2. Association between ram HCW EPD and Rib Eye Area (REA) EPD. Figure 3. Association between ram HCW EPD and Fat Thickness (FT) EPD. 16 Figure 4. Association between ram HCW EPD and French Rack weight . Figure 5. Association between ram HCW EPD and Leg weight EPD. Although traits are correlated, the magnitude of the correlations allow selecting for multiple objectives even when correlations could be considered unfavourable. 17 Results VII Meat quality traits Pearson correlation coefficients between EPDs of animals with post-mortem records (n=424). Trait L* a* b* WBSF (KgF) SWT (kg) REA (cm2) FT (mm) HCW (kg) 0.22 0.16 NS GR (mm) -0.22 0.24 NS - 0.14 NS NS NS 0.47 NS NS 0.15 NS 0.46 0.35 NS Selection NSfor heavier and NSmore muscling carcasses will increase colour. NS NS 0.15 0.23 are the NSmost Lightness NS and redness relevant for consumers acceptability. NS NS NS 0.27 0.20 0.22 higher IMF is linked to NS NS -0.20 -0.13 -0.23 -0.29 better tenderness. NS IMF (%) extreme selection for muscling NS SFA (%)had unfavourable or fatness effect on meat quality. NS MUFA (%) Positive correlations of FTNSand GR NS NS NS with IMF: increasing total content of fat carcass by selection on in NS: correlation non-statistically different form zero (p>0.01). vivo or post-mortem criteria will lead to higher levels of IMF. PUFA (%) IMF (%) -0.65 decreasing IMF -0.26 would increase the proportion of “healthier” fatty acids. 18 Conclusion • In order to improve carcass weight and quality traits, currently published EPDs (i.e. SWT, REA and FT) could be used, due to the positive correlations between EPDs of in vivo and post-mortem traits. • Although there is a general trend of reducing meat fat, evaluated lambs in this study did not present a high degree of fatness, probably due to the leanness of the breed and management. • This emphasis the relevance of evaluating selection objectives taking into account the differences between production and crossbreeding systems, and demands from global or niche markets. 19 Conclusion • Preliminary estimates of genetic parameters suggest that there is sufficient genetic variation for genetic improvement of lamb carcass and meat quality traits by selection. • Furthermore, the estimates of genetic correlations provided very useful insight of some antagonistic associations. • Nevertheless, even being of moderate magnitude there is scope for obtaining favourable genetic progress by the identification of suitable selection criteria and implementation of appropriate selection indexes. 20 Next steps: - Publication of carcass traits EPDs: HCW, Rack and Leg (Sep, 2014) - Development of a terminal selection index. 21 Thanks! 22
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