The Game Breeding Game: Where are we heading? Jacques van Rooyen & Helena Theron The Game Breeding Game: What are the rules of the game? SA Stud Book Elite Breeding Symposium 30 April 2014 Bloemfontein Jacques van Rooyen Pri.Sci.Nat Faculty of Veterinary Science, University of Pretoria & Boscia Wildlife Solutions
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The Game Breeding Game: Where are we
heading?
Jacques van Rooyen
& Helena Theron
The Game Breeding Game: What are the rules of the game?
SA Stud Book Elite Breeding Symposium30 April 2014
Bloemfontein
Jacques van Rooyen Pri.Sci.NatFaculty of Veterinary Science, University of
Pretoria
&
Boscia Wildlife Solutions
Contents
1. The game industry: overview and trends
2. Principles of breeding and selection
3. Shift from Ranger to Rancher
4. Game Breeding- What we know & don’t know:
1. Soay sheep
2. Texas longhorn cattle
3. Sable and Roan antelope
5. Record keeping and selection in game
6. The future: genetic management and selection
Game Industry: Why is it important?
Number of game farms: 2,280 (1980) to ±10,000 today
Surface area: 20,5 mil ha (24% of SA rangelands)
Number of game: Vary: 2.5 – 18.6 mil animals
Economic significance 5th largest agric sector @ R10bil GDP
Plains Game Recent reduction in sale intensity (saturation..?) (Brandon Leer)
High value species/varieties Significant price growth over 10 years... For how long? Competition in animal
performance will increase.
Future: increased competition = increased importance of sound breeding practises –MEASURING AND RECORDING WILL PAY
What to measure and what to record???
Du Toit et al 2013, ABSA,
WRSA 2013, LBW etc
(P)henotype =
= +
+(G)enotype (E)nvironment
The Basic Principle of gene expression
The animal and its performance is a product of the interaction between its genetic potential
and the ability of the environment to express its genetic potential.
Variance between animals will be because of differences in either their genetic composition
I.e. preserving and managing the environmentin which a population of a species could naturally survive
Managing any threat to the survival of the population
Thus: optimizing for survival
Allow natural selection and the survival of the fittest…
Game Rancher:
Priorities:
Financial gain
I.e. Optimizing both the environment and the genetic composition of a population to optimize animal performance for higher profits
Management & Selection objectives
Animal improvement
Thus: optimizing for performance & profit
Breeder select animals based on selection objectives & criteria
Buffalo
Roan
Sable
Do we fully understand what we do?
Horn Length
WHAT IS THE GAME INDUSTRY MAINLY LOOKING AT?
The current trend: breeding &
valuation of genetic potential...
Single trait selection: Emphasis on horn length (coat colour/combination)
as only trait of economic importance
Selection mainly for horn length
Value of animal: Value of animal based on measured horn length =
subjectively because not necessarily linked to true genetic potential/merit where environmental influence has been accounted for
Value of animal often strongly associated with value of sire or dam
HORN LENGHT
DOES PAY!!
BUT SHOULD WE
ONLY SELECT FOR
HORN LENGTH??
The Soay Sheep example
Nature - Johnston et al 2013
The Soay Sheep example
Significant variation in horn length of rams
One gene: Relaxin-like receptor 2 (RXFP2) Genetic & phenotypic data of 1,750 over 21 years
Two alleles: Ho+ - large horns = high
reproductive success
HoP – small horns = increased survival
Heterozygote advantage in Ho+HoP
The Soay Sheep example
• Mechanism for RXFP2 influence on survival and reproductive success is
unknown....
• Might be due to energy expenditure in three phenotypes, especially
during rut
•NB!! Substantial genetic and phenotypic data!
The case of the Texas Longhorn... Hillis, D.M. (2005)
The Texas Longhorn Example
Texas Longhorn: 40 years of selecting for Horn Length = Benchmark ↑ from 40” to 80” (Hillis2005)
BUT!!
“Given the ↑ heritability of many other NB traits such as: Milk production (0.35)
Scrotal circumference (0.48)
Disease resistance (0.4 – 0.6)
Disposition (0.4)
and the low and even neg. corr. between HL and some other desirable traits , a program that selects only for HL will most certain suffer in overall quality in the long term” (Hillis, 2005)
AND
For NB Traits, most progeny of exceptional parents will not be exceptional… (Hillis 2005)
Limb, Don. (2005)
Hillis, D.M. (2005)
40 Years
Horn growth and reproduction:
Sable & Roan antelope
Horn Length Horn Base Horn Rings Tip – Tip Ear Length Body WeightTestis
circumfr.Age
Horn Length 1.0000.200
0.167
0.706
<.0001
-0.066
0.654
0.115
0.430
0.203
0.161
0.175
0.230
0.309
0.031
Horn Base0.200
0.1671.000
0.032
0.825
-0.004
0.980
0.018
0.903
0.108
0.460
0.190
0.192
0.112
0.446
Horn Rings0.706
.<.0001
0.032
0.8251.000
0.018
0.901
0.116
0.427
0.161
0.270
0.113
0.441
0.458
0.000
Tip – Tip-0.066
0.654
-0.004
0.980
0.018
0.9011.000
0.039
0.790
0.350
0.014
0.134
0.359
-0.160
0.271
Ear Length0.115
0.430
0.018
0.903
0.116
0.427
0.039
0.7901.000
0.318
0.026
0.246
0.088
-0.047
0.748
Body Weight0.203
0.161
0.108
0.460
0.161
0.270
0.350
0.014
0.317
0.0261.000
0.577
<.0001
-0.204
0.159
Testis
circumfr.
0.175
0.230
0.190
0.192
0.113
0.441
0.134
0.360
0.250
0.088
0.577
<.00011.000
-0.003
0.986
Age0.309
0.031
0.112
0.446
0.458
0.000
-0.160
0.271
-0.047
0.748
-0.204
0.159
-0.003
0.9861.000
Pearson’s square Correlations between body measurements