Relationships between temperament, carcass traits and tenderness in Santa Gertrudis steers

Transcription

1 Relationships between temperament, carcass traits and tenderness in Santa Gertrudis steers F. R. B. Ribeiro 1, G. E. Carstens 1, R. K. Miller 1, E. G. Brown 2, and P. A. Lancaster 1 1 Texas A&M University, College Station, TX 2 Stephen F. Austin State University, Nacogdoches, TX

2 Introduction Animals that are calm and docile during handling are said to have good temperaments, while those that are nervous and flighty are said to have poor temperaments (Petherick et al. 2002) Numerous methods have been used to assess animal temperament

3 Temperament background Temperament is defined as an animal s response to handling by humans It is moderately heritable (h 2 = 0.07 to 0.44) Calves with excitable temperaments: Increased stress responsiveness Slower growth Reduced milk production More carcass bruising (dark cutters) Tougher meat

4 Introduction Research have shown that temperament can affect performance and carcass traits Lancaster et al. (2005) reported negative correlations between final EV with: ADG (-0.27) and DMI (-0.22) Final UBF (-0.25)

5 Introduction Tenderness is one of the most desirable characteristics in beef Temperament can affect tenderness Voisinet et al. (1997) showed that more excitable cattle: have higher incidence of dark cutters higher WBS

6 Introduction King et al. (2006) reported that excitable steers had: higher WBS values for group C Same trend in group A No differences in group B Falkenberg et al. (2005) reported correlations between EV and WBS of: 0.23* at weaning and 0.02 at finishing (exp 1) 0.10 at weaning and 0.02 at finishing (exp 2)

7 Objectives Determine the relationship between temperament, carcass traits and tenderness in finishing Santa Gertrudis steers

8 Material and Methods 113 Santa Gertrudis steers (King Ranch) Test diet (3.0 Mcal/kg DM and 10.1 CP) fed twice a day ad libitum of 76.5% dry rolled corn, 5% chopped alfalfa, 5% coastal hay, 7.5% cotton seed meal, 4% molasses and 2% premix

9 Material and Methods Individually fed for 80 d on a high grain diet Feed intake was measured using a Calan gate system Steers were weighed at 14 d intervals

10 Exit Velocity Measured as the rate of distance traveled (m/s) while exiting a confined area Exit velocity was measured on d 0 d 70 of finishing phase Steers were sorted by d 70 EV of the finishing phase and classified as calm, medium and excitable (± 0.5 SD from the mean)

11 Material and Methods Steers were harvested at a common endpoint of 1 cm BF determined by RTU A 50 g sample was collected from the LD muscle after 24-h chill to determine calpastatin activity (Wheeler and Koohmaraie, 1991; and Koohmaraie et al., 1995) Carcass data collected after 48-h chill (CBF, CREA, and MS The 6-12 th rib sections were removed and transported to TAMU meat lab Two steaks were removed from the 12 th rib section for 1 and 14 d aging periods for WBS

12 Results EV on d 0 of finishing phase was not correlated to: ADG (0.02) CREA (0.02), MS (0.02) WBS d1 (0.15), d14 (0.07) and calpastatin (-0.05) EV on d70 was not correlated to: CREA Calpastatin

13 Results EV on d 0 of finishing phase was correlated to: DMI (-0.21) and FBW (-0.31) HCW (-0.26) and CBF (-0.24) EV on d70 was correlated to: DMI, FBW and ADG HCW, CBF and MS WBS d 1 and 14 Therefore, EV on d70 was a better overall predictor for performance, carcass and tenderness traits

14 Phenotypic correlations among d 70 EV and performance traits DMI FBW ADG * -0.3 ** *** *** P < , **P < 0.001, *P < 0.05

15 Effect of temperament classification on performance traits Temperament classification groups a Trait Calm Medium Excitable SE P-value n Exit Velocity, m/s 1.56 x 2.57 y 3.51 z DMI, kg/day 9.79 x 9.19 x 8.16 y Final BW, kg x y z ADG, kg/day 1.11 x 1.03 x 0.94 y a Calm, medium and excitable were ± 0.5 SD from the mean

16 1 Phenotypic correlations among d 70 EV and carcass traits HCW CREA CBF Marbling ** ** -0.1 ** *** ** ** * -0.5 *** P < , **P < 0.01, *P < 0.05

17 Effect of temperament classification on carcass traits Temperament classification groups a Trait Calm Medium Excitable SE P-value n Exit Velocity, m/s 1.56 x 2.57 y 3.51 z Hot carcass weight, kg x x y Ribeye area, cm Backfat thickness, cm 1.31 x 1.21 x 0.89 y Marbling score b x x y a Calm, medium and excitable were ± 0.5 SD from the mean b Small 00 = 400, Modest 00 = 500

18 1 Phenotypic correlations between d 70 EV and tenderness traits 0.4 Shear 0 Shear 14 Calpastatin *** ** *** P < , **P < 0.01

19 Effect of temperament classification on Tenderness Traits Temperament classification groups a Trait Calm Medium Excitable SE P-value n Exit Velocity, m/s 1.56 x 2.57 y 3.51 z Day-1 WBSF, kg 2.55 x 2.78 x 3.16 y Day-14 WBSF, kg 2.09 x 2.26 x 2.34 y Calpastatin activity a Slow, medium and excitable were ± 0.5 SD from the mean

20 Summary More excitable steers consumed less feed, gained slower and were lighter than calm steers based on measuring EV at d 70 EV at d 0 was not correlated to ADG but it was correlated to DMI and FBW

21 Summary More excitable steers had lighter carcass and were leaner compared to calm steers based on measuring EV at d 70 There were no differences in CREA EV at d 0 was not correlated to CREA and MS but it was correlated to HCW and CBF

22 Summary More excitable steers had higher WBS (d 1 and 14), but no difference in calpastatin activity based on measuring EV at d 70 EV at d 0 was not correlated to any of the tenderness traits

23 Implications Calm animals had higher DMI, FBW and ADG than more excitable animals More excitable steers are leaner and lighter than calm steers Calm steers had lower WBS values suggesting that EV measured prior to slaughter may be a better indicator trait for tenderness in finishing steers than when measured at the beginning of the finishing phase

24 Thank you QUESTIONS?