crossbreeding with katahdins

Crossbreeding with Katahdins

SUSAN SCHOENIANSheep & Goat SpecialistUniversity of Maryland Extensionsschoen@umd.edu - 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

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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 Extensionsschoen@umd.eduwww.sheepandgoat.com

Thank you for your attention. Questions? Comments?