crossbreeding with katahdins
TRANSCRIPT
Crossbreeding with Katahdins
SUSAN SCHOENIANSheep & Goat SpecialistUniversity of Maryland [email protected] - www.sheepandgoat.com
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The “Holy Grail” of sheep production (Dr. Charles Parker)
Pounds of quality lamb marketed per ewe per yearHow do we increase it!
How do we increase pounds of quality lamb weaned per ewe exposed?Management Genetics• Management at lambing• Disease control• Parasite control• Predator control• Nutrition
• Selection• Crossbreeding****
What is crossbreeding?•Mating individuals of different breeds or
types.
x Texel x Hampshire/Suffolk x Lacaunex White Dorper
What does crossbreeding actually do?• Creates new
combinations of genes in crossbred animals.
• Crossbred animals have increased heterozygosity (having dissimilar pairs of genes for a hereditary characteristic).
• Heterozygosity is the basis for hybrid vigor (or heterosis).
Why crossbreed?•Hybrid
vigor•Breed
complementarity•Upgrading •Make composite
breed
Hybrid vigor•Superiority of crossbred offspring
compared to the average performance of its purebred parents.
Breed A
Breed B
First cross (F1)
Purebred average
SUPERIOR
HETEROSIS
Estimates of lamb and ewe heterosis effects
Trait Lamb EweBirth weight 3.2 5.1Weaning weight 5.0 6.3Pre-weaning ADG 5.3 --Post-weaning ADG 6.6 --Yearling weight 5.2 5.0Conception rate 2.6 8.7Lambing rate 2.8 3.2Pre-weaning survival 9.8 2.7Lambs born/ewe exposed 5.3 11.5Lambs reared/ewe exposed 15.2 14.7Litter weaning weight/ewe exposed 17.8 18.0Effects expressed as percentage of purebred average (Nitter, G. 1978)
Lamb heterosis for weaning weightPurebred lambs Crossbred lambsA B BA AB
Weight 53 63 62 60Average 58 61
Heterosis 3 lbs. (61-58)5.2% (3/58)
Ewe heterosis for lambing ratePurebred ewes Crossbred ewesA B BA AB
Weight 1.70 1.90 1.84 1.88Average 1.80 1.86
Heterosis 0.06 lambs (1.80-1.86)3.3% (0.06/1.80)
Heterosis in the crossbred ram• Less is known about the effects of
heterosis in the crossbred male.• It is likely that heterosis
influences traits such as libido, conception rate, hardiness, and longevity.
• Increased fertility of crossbred rams used in spring mating has been reported.
• Another use of crossbred rams is to optimize breed composition of crossbred ewes.
• Usefulness and value of crossbred rams has not been fully recognized by US sheep industry.
Benefits of heterosis• Effects of heterosis on one
trait may seem minor, but when total productivity is considered, heterotic effects accumulate to provide a substantial improvement over straightbred sheep.
• Combined effects of lamb heterosis ewe heterosis, and complementarity can increase production by 40 to 50% relative to the average of purebred flocks of different breeds.
A crossbreeding system using terminal sires in a meat sheep operation
SCENARIO 1• Maternal ewes
mated to maternal rams of the same breed.
SCENARIO 3• Maternal ewes
mated to maternal rams of same breed (to produce replacements).
• Maternal ewes mated to terminal sire breed (to produce market lambs.
• Assume no hybrid vigor from production of crossbred lambs.
SCENARIO 3• Maternal ewes
mated to maternal rams of same breed (to produce replacements).
• Maternal ewes mated to terminal sire breed (to produce market lambs.
• Hybrid vigor is included.
SCENARIO 1 SCENARIO 2 SCENARIO 3100 ewes x maternal ram
35 ewes x maternal ram65 ewes x maternal ram
35 ewes x maternal ram65 ewes x maternal ram
Ewe lambs mated Ewe lambs mated Ewe lambs mated
90% of ewes lamb 90% of ewes lamb 90% ewes x maternal lamb92% ewes x terminal lamb (+2.6%)
1.5 lambs raised per ewe
1.5 lambs raised per ewe 1.5 lambs per ewe x maternal1.7 lambs per ewe x terminal (+13%)
20 ewe lambs kept for replacement
20 maternal sired lambs kept for replacement
20 maternal sired lambs kept for replacement
Rams purchased Rams purchased Rams purchased
115 market lambs sold at 114 lbs. @ $1.50/lb
27 maternal-sired lambs sold at 114 lbs @ $1.5088 terminal-sired lambs sold at 128 lbs. @ $1.50
27 maternal-sired lambs sold at 114 lbs @ $1.50102 terminal-sired lambs sold at 128 lbs. @ $1.50
$19,665 $4617 $16,896$21,513 (+9.4%)
$4,617$19,584$24,201 (+23.1%)Source: Strategic use of terminal sire meat breeds to improve flock
production, David L. Thomas & Thomas W. Murphy, University of Wisconsin
Assumptions and Results
Composite breeds• A new breed formed by
crossing two or more breeds, then selecting within new crossbred population.
• Appeal of composite breeds: simple and practical breeding system to use breed and heterosis effects, an alternative to more complex crossbreeding systems.
Crossbreeding systems
Terminal crossbreeding systems
Do all traits respond to crossbreeding?• Traits that are lowly
heritable respond the most to crossbreeding, i.e. have the most hybrid vigor.
▫ Reproduction▫ Resistance▫ Fitness▫ Longevity
• Crossbreeding (heterosis) has little to no effect on traits that highly heritable.
Example: Carcass traits
• As heritability increases, crossbreeding has little to no effect.
Breed complementarity• No one breed of sheep is best of
all traits, not even Katahdins!
• Crossbreeding takes advantage of breed complementarity.
▫ Breed complementarity is the combining of desirable traits from two or more breeds into one animal.
▫ Strengths of one breed will offset the weakness of another breed.
▫ To maximize the benefits of breed complementarity, breeds must be chosen wisely; they must complement each other.
Katahdin criticisms• They don’t grow fast
enough• They lack muscling.• They finish too light• They have too much
internal fat.• Their lambs are
suitable for all markets.▫ Hot house (30-50 lbs)▫ Commodity (over 120)
Improvement of carcass merit while maintaining parasite resistance in crossbred Katahdin lambsFeedlot finished, artificial parasite challenge
Katahdin Suffolk TexelPrimary infection no differencesChallenge infection
757 epg 226 epg 462 epg
Worm burdens no differencesADG not statistically significant
0.71 lbs/d 0.88 lbs/d 0.77 lbs/d
REA different no differences2.13 in2 2.67 in2 3.04 in2
Leg score 11.0 12.0 12.8
Para
site
sG
row
th
Car
cas
s
West Virginia University and Virginia Tech, 2016
Performance of crossbred Katahdin lambs, pasture-raised
TraitSire breed
Katahdin Dorper Texel SuffolkBirth weight no differenceWeight, d-30 Lighter Intermediate HeavierWeight, d-120, lbs.
88.0 ± .13 92.6 ± .13 90.4 ± .13 99.2 ± .13
ADG, d 0-240, lb/d
0.29 ± .004 0.31 ± .004 0.31 ± .004 0.35
± .004FEC, d-90, epg 1469 2380 1085 1990
FEC, d-120, epg 1159 ± 534 5069 ± 877 1159 ± 534 5069 ±
877# lambs dewormed 55 ± 7% 67 ± 7% 43 ± 7% 70 ± 8%
Frequency of Tx, # 0.7 ± .1 1.2 ± .2 0.6 ± .1 1.2 ± .2
Age at first Tx, d 173 ± 6 155 ± 7 180 ± 7 157 ± 7
University of Maryland Eastern Shore (2007)
Improvement of carcass merit while maintaining parasite resistance in crossbred Katahdin lambs90-d summer grazing season
TraitSire breed
Katahdin Suffolk TexelBirth weight, lbs. 9.3 10.1 naLambing difficulty no differences observedPre-weaning death loss 0.08 0.43 0.11Adj. weaning weight, lbs. 52.5 56.4 58.0 End weight 64.4 67.9 77.4ADG 0.132 na 0.198Fecal egg counts no differences observed% lambs requiring deworming 63 90 na
West Virginia University and Virginia Tech, 2016
What crossbreeding is not•Indiscriminate mixing (crossing) of breeds.
X
What crossbreeding is• Crossbreeding is a systematic use
of breed resources to create animals of specific type for specific goals.
1. Crossbred lamb(terminal cross)
2. Crossbred ewe3. Crossbred ram
• A good crossbreeding program combines breeds with complimentary traits.
About crossbreeding with Katahdins• If crossbred (with
wooled breeds) are retained, they will probably require shearing.
• The fleeces from hair x wool sheep should be discarded. They should be discarded. They should not be mixed with wool and/or taken to wool pools.
SUSAN SCHOENIANSheep & Goat SpecialistUniversity of Maryland [email protected]
Thank you for your attention. Questions? Comments?