The NSW Agriculture Research project is evaluating implications of selection of cattle for muscling, using Live Muscle Score (LMS). This scoring system expands the A (very heavy muscled) to E (very poorly muscled) into a 15 point scale (A+, A, A- to E-).

This article summarises early and current results of this work. 

(Simmental Australia takes no responsibility for the accuracy of these reported results, and 
indemnifies NSW Agriculture if they are inaccurately reported).

RESULTS FROM EARLY STAGE of PROJECT

* In Light Weight Animals, each 1 LMS  advantage generated:
    1.9% Increase in Dressing Percentage,     4.25% Increase in Retail Meat Yield, 
    for a 15% increase in Value or $52.50 per head.

Evaluation of Animals with High ("B") versus Low ("D") Muscle Scores

Follow up Project (heavier Cattle)   -  Similar results

1 LMS     = 1.7% Increase in Dressing Percentage

               = 1.5% Increase in Saleable Meat Yield

               = Reduction in Fat Trim Required

               = $57 increased return to butcher

Overall Results

Increased LMS   = Increase in Dressing Percentage

                          = Increase in Saleable Meat Yield

                          = $60 to $70 /hd increased price per LMS

1991 Saleyards NLMRS Results

Analysis of the National Livestock Market Reporting Service (NLMRS) saleyards reports in 1991, identified price differences of:   14.0c/kg for each increased muscle score 
                                             (range "E" very poor to "A" very heavy muscle) and 
                                 5.5c/kg for each Fat Score 
                                             (range "1" very lean to "5" very fat).

1 LMS = $75 higher price per hd (based on a 500 kg animal)

Distribution of Muscle Scores in Saleyards

Despite the higher value of "B" muscled cattle, there are very few well muscled cattle marketed through saleyards:

      less than 10% of “B” LMS in market
      Approx    70% of “C” LMS in market  
      Approx    18% of “D” LMS in market 

Genetics of Muscling  -  (LMS = Live Muscle Score)  (EMA = Eye Muscle Area)

    Correlation:            LMS : EMA   = 0.60

    Heritability:                      LMS   = 0.45      EMA   = 0.40

Current Project

Used Angus bulls with similar EBVs for Growth but with either High Muscled (HM) ("B") or Low Muscled (LM) ("D")

Latest results for Second Generation (Angus x selected HM or LM females):

Calving Difficulty                   NIL incidence in both HM and LM Lines

Birth Weight                           HM calves were 1.1 kg lighter and smaller in girth and height

Weight Gain                            No Difference in weight gain to any age between HM and LM lines

Weaners (Fat)                         HM line weaners were leaner than LM line. ( – 0.4 mm at both Rib and P8. (av 3.4 & 5.2))

Weaners (LMS)                      HM weaners 1 LMS greater than LM line. 
                                                          (HM weaners avg “C+” versus LM avg weaners avg “D+”)

Weaners (EMA)                     HM weaners 3.2 sqcm greater eye muscle area than the LM line.                           
                                                         (HM weaners avg 40.6 sqcm versus LM avg weaners avg 37.4 sqcm)

Saleable Meat Yield               HM Line Increased SMY,  with Lower Fat Cover,  and Increased Bone

Economic Evaluation of Financial Effects  – Using "Beef-N-Omics" Model

Example:              A self replacing yearling production system on improved native pasture with a 
                               90% calving rate and average liveweight of 500 kg.

                                                                                     GM  per Cow ($)      GM  per ha ($)

Base Gross Margin (GM) per Cow =                                $225                         $90.10

Reducing Fertility to 70% reduces GM by                          $25                           $17.50

Increasing Weight Gain by 20% increases GM by            $19                             $1.60
               (Allowing for reducing numbers of cows due to their increased weight)

Increasing Muscling to “B” LMS increases GM by         $18                            $18.00

Decreasing Muscling to “D” decreases GM by                $22                            $22.00         

So selection to increase muscling in the herd (including to cow herd) can increase profits dramatically 
without affecting stocking rate or reducing other herd performance factors.               

SUMMARY

*  Increasing muscling via purebreeding will be slow due to moderate heritability and a small variation 
      in the population.

*  For rapid progress, utilize between breed variation in muscling.

*  Using highly muscled bulls does not necessarily increase calving problems or decrease growth rate.

*  The change in the distribution of progeny LMS (e.g. low muscled) is more significant than the actual       
        quantitative change in  muscling.

*  Increase in height will decrease LMS unless selection is applied for muscling.

*  Future selection for maturity pattern should consider both frame score and LMS.

*  Selection for muscling must also be applied to the Female herd for significant improvement 
      to occur.