Goats & Sheep Test 4

How many chromosomes do sheep have?

27

How many chromosomes do goats have?

30

What is the equation for estimated breeding values?

EBV = b (P₁ - P_A)

Where b= the weighting factor of inheritability
P1= individual record
PA= contemporary age group

What is the EBV for this animal? Ram A has a grease fleece weight of 18 pounds and his contemporaries average 12 pounds. The inheritance of grease fleece weight is 0.4.

Ram A has an EBV for grease fleece weight of 0.4 x (18-12) = 2.4 pounds

Information on ______ is important in estimating breeding values for lowly heritable traits

relatives

____ is used to denote this sample half of an animal’s breeding value that is passed to offspring. This is half of EBV

expected progeny difference (EPD)

The average EPD in the base population is

zero

The generation interval (L) for sheep is

five to six years

The generation interval for rams is

one to four years

What is a progeny test?

A method of estimating the breeding value of an animal by the average performance or phenotype of it’s offspring

Which method estimates an animal’s breeding value by combining all the performance information available for a trait

Combined selection

Which method of selection addresses the multiple-trait issue by focusing on one trait at a time?

Tandem selection

Which method of selection may be practiced for two or more traits simultaneously?

Multiple-trait method

WHat is the selection index?

It ranks individual animals for overall economic merit based on two or more traits and is the most efficient method

What tends to happen during crossbreeding?

They tend to be more vigorous, fertile, and may grow faster than average purebreds

Levels of heterosis tend to be the highest for ____ and _____, lower for _____, and near zero for ______

survivability and early growth, birth weight, carcass traits

In replacement females, heterosis has large effects on

fertility (especially in ewe lambs) and on preweaning growth and survival, with modest effects on ewe birth weight and fleece traits

Purebred flocks sell

breeding stock or breeding value

commercial flocks do not sell breeding value but pounds of

quality lamb, wool, and/or milk

What does NSIP stand for? What do they do?

National Sheep Improvement Program (also includes goats)
accepts on-farm, performance records from participating flocks and returns Estimated Breeding Values (EBVs) for reported traits

NSIP is the organization that provides what for the US sheep and goat industry?

EBV’s, they provide both a LAMBPLAN and a KIDPLAN

EBV is ____ the value of an EPD

twice

What are the 2 kinds of EBVs

Herd EBVs

Across-herd EBVs

What are Herd EBVs

Calculated when a herd is not connected to other NSIP flocks

What are Across-herd EBVs

Herd has genetic linkages with other NSIP herds, EBVs from individuals in other herds

Half-siblings share about ____% of their genes

25%

First cousins share approx. ____% of their genes

12.5%

What does WWT stand for?

Weaning weight

What is maternal weaning weight (MWWT)

milk production, mothering ability

What is the postweaning weight (PWWT) based on?

the 120-day weight

What is Fleece weight (GFW)?

Grease fleece weight, wool production

How is the fat depth for an EBV measured?

mm - fatness between the 12th & 13th ribs

How does the USDA classify yield grades for carcasses based on estimated fat depth over the loin eye at the 12th rib

Yeild grade 1-5

What is Entropion?

Inverted eyelids, a heritable trait that can be aggravated by environmental conditions

Treatment by removing extra skin (done by a veterinarian)

What is cryptochidism?

One (unilateral) or both (bilateral) testes of the ram are retained in the abdomen rather than descending into the scrotum.

What is Neuronal Ceroid Lipofuscinosis?

Inherent blindness, animals may wander aimlessly and become separated from the flock and stand with head
“stargazing”

An earless animal also probably has this defect too:

cleft palatte

What is wattles?

extra skin appendage-like tissues on the neck

How many different genetic tests can goats go through?

3

WHat are the standard pregnancy rates?

100% for 200 ewes or less
98% for 201-750 ewes

96% for 751 or more

All ewes must breed within a ____-day time period

34

All does must breed within a __-day time period

42

How do you determine pregnancy rate?

pregnancy rate = # of ewes pregnant / number of ewes exposed to a ram x100

The standard lambing rate should be

120%-150%

How do you find lambing percentage?

number of lambs raised / number of ewes exposed

What is the standard lamb/kid survival rate?

95%

What are the two culling methods?

Tandem - selecting one trait at a time until a certain level of performance is achieved

Independent culling levels - set minimum standards for traits involved in multi-trait selection

What is the 1st decision when it comes to managing ewes?

Buying vs. raising

What are the pros/cons of buying your ewes?

It’s easier → can breed all females and sell lamb/kids

Can purchase replacements from farms

sometime mature females (still sound) are available

Might be cheaper to buy replacements

What are the pros/cons of raising you own ewes?

You get to maintain a (mostly) closed flock/herd

Can breed traits that are most important to you

Can raise replacements the way you want

Might be cheaper to raise instead of buy replacements

When buying, what do you need to be conscious of?

Most diseases walk onto your farm in an animal

Purchased animals may introduce resistance worms to your farm

What are the types of sires?

Maternal -sires that excel in maternal and fitness traits (use to sire replacement females)

Terminal - sires that excel in growth and carcass traits (used to sire market lambs/kids)

Dual purpose - suitable as either sire or dam breed

What should you consider when choosing sires for replacement female production

Should be of desired breed/cross

Need to have desired coat/fiber type

Need to have desired level of reproduction

Need to have desired level of fitness

Need to have desired milk production

What are the criteria for selecting replacement females?

Visual Appraisal

Performance Evaluation

Genotype or Serotype

What is important to ewe conformation?

Length, width, and depth of body. She needs to eat, walk, and feed two lambs. W

What is the order of checking for ewe conformation

Teeth - for eating

Feet - need to be able to walk to find food

Udder - to rear two lambs

What are the methods of performance evaluation?

Individual - selection on the basis of the individual animal’s own performance

Pedigree - selection on the basis of the performance of the animal’s parents and other relatives

Progeny - selection on the basis of the performance of the individual’s offspring

Breeding values - mathematical prediction of a genetic merit of an animal that uses multiple data sources including performance of individual and and all of it’s relatives

Individual animal performance is based on

season and date of birth

type of birth and rearing

weaning weight / weaning ratios

post -weaning weights /ratios

Fecal egg counts (weaning and post)

FAMACHA scores

Fiber traits; weight length yield

Carcass traits; fat depth, loin depth

It is customary to cull ~___% of the flock each year

15%

What is the primary reason for culling ewes?

Age

Ewes tend to be most productive between the ages of

3 AND 6

You cull anytime there is a

prolapse. Rectal, vaginal, or uterine

You should cull females that are chronically infected with

foot rot or scald.

It is genetic

You should cull females that require frequent or regular

deworming

To improve parasite resistance in a flock, cull females with the

highest fecal egg counts