Shahid Mahmood, Walter T. Dixon, Heather L. Bruce Department of Agricultural, Food and Nutritional Science University of Alberta, Canada

Transcription

1 Effect of cattle production practices on the incidence of dark cutting beef Shahid Mahmood, Walter T. Dixon, Heather L. Bruce Department of Agricultural, Food and Nutritional Science, Canada September 28 th, 2016 Ottawa, Canada 1

2 Dark cutting beef Dark cutting? 2

3 Dark cutting beef Glitches with dark cutting Old Fresh Tenderness Shelf life Taste/Flavour 3

4 Dark cutting beef Incidence and repercussions Dark cutting frequency % Price Discount $40/cwt or $340/head Reducing dark cutting 1.2 to 0.8% Saves: $1.77 million Jones &Tong 1989, Donkersgoed 1997, 2001; CBQA, 2011 Report BCRC

5 Dark cutting beef Potential Factors Pre-slaughter stress Carcass/Abattoir Probably Animal mixing Animal Handling Transportation Weather Estrus Carcass weight Musculature Fat depth Chilling Growth promotants Production systems Muscle metabolism Nutrition Infection Immonen et al., 2000; Jones & Tong,1989; Kenny & Tarrant; 1988; Scanga et al. 1998; Kyla-Puhju et al.,

6 Objectives Production system Melengestrol acetate Cattle gender Weather Dark cutting Beta agonist Pre-slaughter management Growth implants 6

7 Material and Methods Data Collection Two data-sets I. Data set A (Single Farm) II. Data set B (Farm X, Y and Z) Information Cattle gender Production system (Calf-fed vs Yearling-fed) Melengestrol acetate (MGA) Hormonal growth promotants Beta agonist Feeding Carcass data 7

8 Material and Methods Data-set A (n=2058) Calf-fed cattle I. Heifers and Steers II. Optaflexx vs No Optaflexx Yearling-fed cattle I. Heifers and Steers II. Optaflexx vs No-Optaflexx Calf-fed received two implants (Ralgro + Synovex Choice ). Yearling-fed received One implant (Synovex Choice ). 90 days gap between terminal implant and slaughter. 8

9 Material and Methods Data-set B (n = 86408) Yearling-fed Heifers and Steers I. Pasture grazed or grass fed (GY) II. Backgrounded yearling (BY) Calf-fed Heifers and Steers I. Winter calves (WC) II. Fall calves (FC) Cattle Breeds Red (predominantly Angus or Limousine) Black (predominantly black Angus) Red white-face (predominantly Hereford) White or tan to grey (Charolaise) 9

10 Material and Methods Data-set B Hormonal Growth Implants Calf-fed Cattle Calves < 700 Lbs Ralgro--1 st Component TE nd Implant Component TE rd Implant Calves > 700 Lbs Component TE st Implant Component TE nd Implant Yearling-fed Cattle Cattle < 1000 Lbs Component TE st Implant Component TE nd Implant Cattle > 1000 Lbs Component TE st Implant Steers: Optaflexx TM for days Heifers: MGA until 2 days before shipment 10

11 Material and Methods Data-set B Slaughter seasons Winter (mostly below 0 C and as low as -20 C) December January February Spring (above 0 C) March April Summer (9 C to 20 C) May to September Fall (-17 C to +14 C) October November 11

12 Material and Methods Statistical Analyses Separate analyses for data-set A and B. Used statistical analysis system (SAS, Version 9.3). Catmod procedure and logistic regression to estimate the likelihood of dark cutting. General Linear Models procedure for the analysis of variance. 12

13 Dark-cutting frequency % Results Data-set A (n=2058) Overall dark-cutting: 2.23% Effect of lairage time after shipment T R U C K I N G 0 Same day Overnight Day 4th 13

14 Dark-cutting frequency % Results Dark-cutting frequency % 6 Data-set A Effect of lairage time after shipment Same day Overnight Day 4th Separate analysis 0 Calf-fed heifers Yearling-fed heifers Calf-fed steers Yealing-fed steers Calf-fed and yearling-fed heifers were at greater risk of cutting dark. Steers were less likely to cut dark regardless of the production system. 14

15 Grade frequency % Results Data-set A a b c d d e f g j i j i i i h i Prime AAA AA B4 Production system (Calf vs Yearling) interacted with Optaflexx treatment (Optaflexx vs No Optaflexx ). Yearling cattle received no Optaflexx had increased frequency of Prime and AAA carcasses. No effect on the likelihood of grading Canada B4 (dark-cutting). 15

16 Dark cutting frequency % Results Data-set B Overall dark-cutting: 0.85% Effect of implant, gender and production system a b c de e d d ed Heifer Steer Calf-Imp2 Calf-Imp3 Year-Imp1 Year-Imp2 Interaction of gender with implant nested within production system (Calf-fed vs Yearling-fed). No clear trend for implant effect. 16

17 Dark cutting frequency % Results Data-set B Effect of production system and gender a b cd b c f de e Backgrounded-yearling (BY) Grass-fed yearling (GY) Fall calves (FC) Winter calves (WC) 0 Heifer Steer BY GY FC WC Increased frequency of dark cutting in WC, FC and BY heifers. Grass-fed (GY) heifers and steers had reduced frequency of dark cutting. 17

18 Dark cutting frequency % Results Data-set B b b cd Heifer a c de f Steer e Backgrounded-yearling (BY) Grass-fed yearling (GY) Fall calves (FC) Winter calves (WC) BY GY FC WC Slaughtered in all the four seasons Slaughtered in fall and summer Production system was confounded with slaughter season/months. Analysis incorporating season, gender and four production systems was redundant. 18

19 Dark cutting probability% Results a Data-set B b b bc d cd cd d e e ef e f f f BY GY BY GY Heifer Steer Fall Spr Sum Win e Backgrounded yearling (BY) and grass-fed (GY) yearling cattle were slaughtered in all four seasons. Three-way interaction of gender, production system (GY and BY) and season. Slaughter season influenced the likelihood of dark cutting. Trend of production system effect remained as in the analysis with gender and production system alone. 19

20 Results Measurements Analysis of Variance Fall calved steers Winter calved steers A AA AAA Prime B4 A AA AAA Prime B4 n Start weight (kg) 297 e (3.02) 298 e (0.57) 291 f (0.54) 282 f (6.03) 285 f (5.53) 334 de (4.45) 331 d (0.78) 326 de (0.68) 320 e (6.08) 326 de (7.86) Days to finish 222 d (1.52) 227 c (0.29) 235 b (0.27) 246 a (3.04) 241 a (2.78) 175 h (2.24) 182 g (0.39) 190 f (0.34) 201 e (3.06) 189 f (3.96) Carcass weight (kg) 388 e (1.59) 397 b (0.3) 400 a (0.28) 402 a (3.19) 380 f (2.92) 383 ef (2.35) 397 b (0.41) 401 a (0.36) 399 ab (3.22) 388 ef (4.1) Grade rib eye area (cm 2 ) 104 a (0.65) 97.4 b (0.12) 90.9 d (0.11) 84.2 g (1.29) 94.5 bc (1.18) 100 a (0.98) 95.6 b (0.17) 90.5 d (0.15) 84 g (1.3) 94.6 bc (1.72) Dark cutting steers were as heavy as most normal grades at the start of finishing. Dark cutting steers either finished in the same mean days or greater than normal grades. Mean carcass weight for B4 steers was lower than rest of the grades except Canada A which had grea greater than all the other grades. 20

21 Results Results for fall-calved heifers were same as that for fall-calved and winter-calved steers. Increased dark cutting in heifers and steers may be due to reduced carcass weight. Increased carcass weight itself may not be responsible for reduced dark cutting but may represent increased growth rate because: Fast growing cattle may have less response to stress. May have adequate muscle glycogen. May differ in utilization of muscle glycogen. (Smith et al., 1999) 21

22 Conclusions Increased lairage/frequent shipping increased the likelihood of dark cutting. Heifers especially the calf-fed are more prone to cut dark than steers. Slow growing cattle are at greatest risk of cutting dark. Lack of implant effect was likely because there was adequate gap between terminal implant and slaughter. 22

23 Acknowledgment Dr. Walter Dixon Dr. Heather Bruce 23

24 Thank You! 24