Tailoring a terminal sire breeding program for the west

Transcription

1 Tailoring a terminal sire breeding program for the west Ron Lewis, Department of Animal Science, University of Nebraska-Lincoln Utah Wool Growers Association Leading Edge Sheep Production Part II Little America Hotel, Salt Lake City, Utah June 24, 2016

2 My talk Some principles Breeding values Selection index What s key? Growth Carcass Longevity & fitness A couple of examples New Zealand United Kingdom Where we are Genetic gains Connectedness Opportunities Potential scale Genomics?

3 Genetic evaluation Genetic evaluation is about parsing P = G + E Genotype (EBV): WWT: 5.37 kg PWWT: 9.01 kg PFAT: mm PEMD 1.25 mm

4 Breeding value Breeding value (BV) The value of the genes that a parent transfers to its offspring for a given trait Seldom known and therefore must be estimated (EBV) Estimate becomes more accurate when a trait is More heritable More persistently measured Particularly if on closer relatives

5 Selection index Breeders seldom wish to select for one trait in isolation Profit usually depends on several traits Optimising profit therefore depends on placing the right emphasis on each trait to be improved A selection index predicts genetic merit for a combination of several traits Key to their design is deciding which traits to improve

6 What s key? Growth Pre-weaning Post-weaning Longevity & fitness Ram survivability Ewe productive lifespan Carcass Carcass weight Lean & fat contents Quality & yield grades

7 Index change (NZ$/year) New Zealand example Sheep Improvement LTD (SIL) Began in Central Performance Test (CPT), Advanced Central Evaluation (ACE) SIL CPT/ ACE Began in Average gain up to labelled year (Young and Amer, 2009)

8 United Kingdom example United Kingdom Lean growth index Developed by Scottish Agricultural College Began 1989 In 9 years, 1 kg increase in lean weight in 20 kg carcass (+ 5%) Selection goal Increase lean carcass weight (+3) Little change in carcass fat weight (-1) Selection criteria Live weight (+) Muscle depth (+) Fat depth (-) (Simm and Dingwall,1989; Lewis et al., 2002; Simm et al., 2002)

9 Lean Growth Index score United Kingdom example Gains in industry schemes Charollais Meatlinc Suffolk Texel 150 ` Year Gains of 2% per annum Comparable to dairy industry (Courtesy: Signet)

10 United Kingdom example Effects on marketable output Comparison of crossbred lambs sired by high versus low index terminal sires 6,400 lambs sired by 90 rams Rams differed by 200 index points Benefits 0.56 kg heavier cold carcass weight 0.47 kg more saleable meat yield (1000 carcasses) 353 extra retail value per high index ram over its lifetime (Lewis et al., 2006., Márquez et al., 2012; Márquez et al., 2013a,b; Márquez et al., 2015)

11 Where we are

12 kg Trends in Suffolk EBV Weaning wt. EBV All Year Post-weaning wt. EBV Year

13 kg Trends in Suffolk EBV Weaning wt. EBV All Bunker Hill Year Post-weaning wt. EBV Year

14 mm Trends in Suffolk EBV Fat depth EBV Muscle depth EBV All Year Year

15 mm Trends in Suffolk EBV Fat depth EBV Muscle depth EBV All Bunker Hill Year Year

16 Carcass Plus Index Developed to improve carcass value in Australian sheep industry Provides a good assessment of carcass value in U.S. terminal sires Criteria (EBV) Index Weight Relative emphasis Weaning weight (kg) % Post-weaning weight (kg) % Fat depth (mm) % Muscle depth (mm) %

17 Carcass Plus index Trends in Suffolk Carcass Plus index 160 Carcass Plus index All Bunkerhill Year

18 Elite sires report Top Suffolk sires ranked on Carcass Plus Index score

19 Connectedness Seedstock flock sizes generally small Few animals to choose among within flock, which slows genetic progress Fair comparisons of genetic merit of animals across flocks not always possible Husbandry differences between flocks can mask genetic differences

20 Connectedness Solution? Form genetic linkages, or connectedness, among flocks Most easily achieved by systematic sharing of rams

21 Connectedness

22 Potential scale 65,000 ewes bred ( 43,000 to terminal sires) 3 rams / 100 ewes / year Annual breeding ram inventory 1,290 rams Cull 50% 720 new breeding rams Produce 1,440 ram lambs per year Average ram life of 1.8 year 130% lamb crop 2,215 recorded lambings of terminal sire ewes

23 Genomics? Genomic selection Limited opportunities currently given industry dynamic Still, need to begin to establish a reserve of DNA samples on well-chosen NSIP sheep

24 Genomics? Genomic selection Limited opportunities currently given industry dynamic Still, need to begin to establish a reserve of DNA samples on well-chosen NSIP sheep Genetic tests for some major genes OPP virus susceptibility Scrapie susceptibility Muscling (myostatin) Parentage determination

25 Thank you Questions?