RTU measurements as early indicator for carcass characteristics in - - PowerPoint PPT Presentation

RTU measurements as early indicator for carcass characteristics in Nguni cattle

18 September 2017

Jani de Vos

• Prof. E van Marle-Koster
• Dr. H Theron, Dr. J van der

Westhuizen

Contents:

Background Aim Materials & Methods Results Discussion Conclusion & Recommendations Acknowledgements References

Yolanda Venter

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▪ SA – 13.7 million heads of beef cattle ▪ Per capita consumption 2016/2017 - 20.9kg/year (DAFF 2016) ▪ 75% cattle finished in feedlot (DAFF, 2016) ▪ Majority of cattle marketed through abattoirs come from feedlots

Background

Yolanda Venter

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16% 12% 12% 9% 9% 6% 5% 4% 5% 5% 4% 3% 5% 5% Bonsmara Hereford Simmentaler Limousin SA Angus Beefmaster Drakensberger Sussex Charolais Holstein Afrikaner Santa Gertrudis Brahman/ Simbra/ Brangus Other/ non-descripts like Nguni

Cattle breeds finished in feedlots:

Created from: Scholtz & Theunissen, 2010

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Background

• Majority of cattle in feedlots
• Bos Taurus and cross breeds
• Non-descript cattle dominate the emerging sector with the Nguni and Brahman

breeds also playing a significant role (Scholtz & Theunissen, 2008)

• Investigate the opportunity for Nguni cattle in feedlots
• Due to growing numbers
• Limited veld for finishing (Mapiye et al., 2007; Strydom, 2008)

https://www.google.co.za/search?rlz=1C1AVNE_enZA679ZA679 &biw=1366&bih=638&tbm=isch&sa=1&q=large+Nguni+herd+afri ca&oq=large+Nguni+herd+africa&gs_l=psy- ab.3...10182.11627.0.12081.6.6.0.0.0.0.0.0..0.0....0...1.1.64.psy- ab..6.0.0.bH0FUDyh9NE#imgrc=mWTIfTJjV5815M:

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Background

▪Feeding costs – 55-75% of total costs ▪Growth & efficiency: ADG, Efficiency of use of feed (Muchenje et al., 2009): RFI, FCR, Kleiber ratio ▪Carcass quality is main price determinant ▪Meat quality characteristics: ▪Fat, juiciness, tenderness & flavour of the meat (Lazzaroni, Gigli & Gabiňa, 2007) ▪SA consumers prefer a carcass score of A2 (Young animal, lean meat) (Webb, 2015)

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Background

• Evaluation of carcass quality with post mortem slaughter

methods are expensive & time consuming

• RTU scans: Non-invasive, cost effective, more time

efficient Use of RTU scans to measure the trait ✓ Eye muscle area ✓ Fat depth ✓ Intramuscular fat (Marbling) (Muchenje et al., 2008; Lopes et al., 2016)

• Traits have a moderate to high heritability – selection
• Limited use of RTU in Nguni cattle

Yolanda Venter

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Eye muscle area (carcass)

RTU scan Marbling Subcutaneous fat

Eye muscle area

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Background

• Breed bulls with these characteristics for improved production

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The aim was to determine whether RTU measurements can be a sufficient predictor for carcass traits in Nguni cattle raised in feedlots.

Aim

Yolanda Venter Yolanda Venter

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• 60 Nguni bulls finished in a commercial feedlot
• Cattle weighed and RTU measurements recorded:

Materials & Methods

Days on test Date Measurements

• 32

15-Jul Weigh animals: Arrival weight 16-Aug Weigh animals: Start weight 9 25-Aug Weigh animals 44 29-Sep Weigh animals RTU measurements: Rump fat, Rib fat 72 27-Oct Weigh animals RTU measurements: EMA, Rump fat, Rib fat 91 15-Nov RTU measurements: EMA, Rump fat, Rib fat 99 23-Nov Weigh animals 105 29-Nov Slaughtered at A2 carcass grade. Slaughter weights

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Materials & Methods

• Real time ultrasound measurements:

Marbling (intra muscular fat) Fat depth (inter muscular fat) Eye muscle area (EMA)

• Rib fat, eye muscle area (EMA) and rump fat measured using RTU at 72 and 91

days on test respectively.

• Animals slaughtered at 105 days at A2 carcass grade.
• Statistical analyses were preformed using SAS Enterprise Guide (SAS Institute Inc.

2010).

• Phenotypic correlations were estimated between the different traits.

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Results & Discussion

Variable Mean  SE Minimum Maximum Start weight (kg) 225.3  2.9 184 288 Slaughter weight (kg) 378.7  2.5 328.5 444.0 ADG (kg/day) 1.6  0.1 1.2 2.0

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Results & Discussion

Variable Mean Minimum Maximum Rump fat (mm) 6.0  0.1 3.5 8.8 Rib fat (mm) 3.9  0.1 2.1 6.6 EMA (cm2) 56.0  0.5 44.0 69.0

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Results & Discussion

Current study Comparative Nguni studies Other breeds Slaughter weight (kg) 225.3 220 - 390 413 - 440 ADG (kg/day) 1.6 1.08 – 1.5 1.28 – 1.8 EMA (cm2 ) 56.0 68.1 – 70.2 75.9 - 84.8

Strydom et al., 2001; Mapiye et al., 2007; Strydom, 2008; Scholtz & Theunissen, 2010; Scholtz & Theunissen, 2011; Caetano et al., 2013; Pereira et al., 2015; Linde et al., 2016

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Slaughter weight Eye muscle area (EMA) Rump fat Rib fat ADG Slaughter weight 0.35

• 0.05

0.06 Eye muscle area (EMA) 0.03 0.09 0.1 Rump fat 0.3 Rib fat ADG

Results & Discussion:

Correlations of traits measured at 72 days on test

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Results & Discussion:

Correlations of traits measured at 91 days on test

Slaughter weight Eye muscle area (EMA) Rump fat Rib fat ADG Slaughter weight 0.49

• 0.04

0.1 Eye muscle area (EMA) 0.14 0.17 0.17 Rump fat 0.35 Rib fat ADG

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Conclusion and recommendations:

• Average slaughter weight for Nguni tend to be lower compared to

composites generally used in feed lots

• RTU measurements compared well to previous studies and could be

used to predict slaughter weight of Nguni cattle.

• The next phase of this study will aim to include RTU in a selection index.

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Acknowledgments

• Nguni breed society for the feedlot trail

which took place at Sernick feedlots

• BGP which is funded by TIA

https://www.google.co.za/search?q=Ann+gadd+art&rlz=1C1AVNE_enZA679ZA679&source=lnms&tbm =isch&sa=X&ved=0ahUKEwjrvfjcl9LUAhVEWxQKHeZJDkUQ_AUICigB&biw=1366&bih=638#tbm= isch&q=Ann+gadd+nguni&imgrc=xyApHbETdSorBM:

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Thank you