Tips for Improving Lambing/Kidding Percentage

TIPS FOR IMPROVING LAMBING

AND KIDDING PERCENTAGES

Management, Genetics, and Selection

SUSAN SCHOENIAN (Shāy nē ŭn)

Sheep & Goat Specialist

University of Maryland Extension

[email protected] – www.sheepandgoat.com

Lambing/kidding percentage

is one of the most important

factors affecting profitability of

sheep and goat enterprises.

$$1 2 3

However, the percentage needs

to be matched to the production

environment, available resources,

and goals of the enterprise.

Range lambing, South Dakota Pasture kidding, Missouri Shed lambing, Maryland

What is lambing/kidding percentage?

100 ewes put with rams (34 days)

96 ewes lambed

178 lambs born

171 lambs born live

160 lambs weaned (marked)

157 lambs sold or retained

Definition, calculation %

Number of lambs/kids born per ewe/doe lambing/kidding [178 ÷ 96] 185%

Number of live lambs born per ewe/doe lambing/kidding. [171 ÷ 96] 178%

Number of lambs/kids born per ewe/doe exposed for breeding. [171 ÷ 100] 171%

Number of lambs/kids weaned (marked) per ewe/doe exposed. [160 ÷ 100] 160%

Number of lambs/kids sold or retained as a percentage of the total number of

females exposed for breeding during a given period. [157 ÷ 100]157%

How do you compare?

Sheep

StateLambs born or docked

per 100 ewes

Iowa 167

Minnesota 158

West Virginia 141

Michigan 140

OHIO 136

Kentucky 129

USA 111

Pennsylvania 97

Texas 77

Source: USDA NASS, JAN 2015

Meat goats

Per doe kidding Average

Number born n=3057(per doe kidding)

1.84

Number weaned n=2906 1.56

Source: Kentucky State University GHIP FEB 2015

90

100

110

120

130

140

150

1973

1975

1977

1979

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

2009

2011

2013

# lambs per 100 ewes (1+ yr)

USA Ohio

Is the industry making any progress?

Source: USDA NASS

40-year trendOhio +31 lambs (0.31 lambs/ewe)

USA +16 lambs (0.16 lambs/ewe)

Establish benchmarks for your farm

TraitYour

farm

Sheep

ProlificSheep Goat

Conception, 1st cycle, % ? > 80 > 80 > 80

Prolificacy, % ? > 200 > 150 > 200

Still births, % ? < 5 < 10 <5

Pre-weaning losses, % ? < 15 < 10 < 10

Post-weaning losses, % ? < 5 < 5 < 5

Lambing/kidding % ? <200 <150 <200

Benchmarks for my farm

Lambing & Kidding Percentage

is a composite trait.

1. Fertility (conception/pregnancy rate)

2. Litter size(number born, prolificacy)

a) Ovulation rate (OR)

b) Embryo survival

3. Survival

a) Perinatal

b) Pre-weaning

c) Post-weaning

Many factors affect lambing/kidding

percentage.

Animal factors Breed

Age

Sex

Genetics

Body weight and condition

Health

Male-to-female ratio

Lambing/kidding interval

Length of exposure

Environmental factors

Season (photo period)

Climate – weather - temperature

Stress

Nutrition

Pasture composition

Lambing/kidding system

Management - labor

How to improve fertility

Management Breeding Soundness

Exam (BSE) for males

Monitor breeding activity with marking harness or painted brisket

Use multiple sires

Male: female ratio

Good nutrition during early pregnancy

Breed in fall

Don’t breed on certain kinds of pasture

Use ram/buck effect to induce estrus

Hormones or CIDRs to induce estrus

Genetics Raise a more fertile breed

Raise a more heat tolerent breed.

Introduce a more fertile breed

Crossbreeding

Use a crossbred ram for breeding

Select a less seasonal breed or breed cross

Selection Select breeding stock

from females that lamb/kid early in season.

Select replacements from females that lamb/kid out-of-season.

Cull open females

Cull females that don’t breed in first heat cycle.

Do not use males with small testicles for breeding.

Breeding Soundness Exam (BSE)Up to 10-15% of rams/bucks are of unsatisfactory reproductive breeding quality.*

1. Physical exam

a) Body condition

b) Structural soundness

c) Health

2. Assessment of reproductive

organs, including measuring

scrotal circumference

3. Semen evaluation

4. Libido (serving capacity)

*https://www.extension.purdue.edu/extmedia/AS/AS-599-W.pdf

At least 30 days before breeding

Scrotal circumference (SC)

Scrotal size is strongly related to semen

production capacity.

There is evidence to suggest that female

progeny from males with larger scrotal

circumference reach puberty earlier than

progeny from males with smaller testicles.

Scrotal circumference can vary by season and

with body condition.

Mature rams should have a minimum scrotal

circumference of 33 cm; 30 cm is acceptable

for ram lambs (6-8 m of age).

It is recommended that mature bucks have a

minimum scrotal circumference of 25 cm; a

minimum has not been established for buck

kids < 14 m.

Libido or serving capacity10% of rams will not mate with ewes.

Serving capacity is a moderately heritable

trait that can be evaluated in a pen test

using females (in estrus).

Indirect selection for serving capacity

Rams born to prolific ewes, and preferably

born as twins or triplets themselves, are more

likely to have a high serving capacity than

rams born to low fecundity ewes. (Australia)

Rams born as co-twin to another ram are more

likely to have a high serving capacity than

rams born as co-twin to a ewe lamb.

(Australia)

No difference in serving capacity of rams born

from high or low line ewes (Montana State

University).

Monitor breeding activity

Marking harness

Painted brisket

Use multiple sires

Use clean-up rams/bucks

Male-to-female ratiosBreeding scenario Male: female Length of breeding season

Mature male 35-50 2 heat cycles

Young male 15-25 2 heat cycles

Synchronized matings 5-10 1 heat cycle

Summer breeding considerationsIncreased body temperature due to high temperatures (>90°F) and

humidity. Also from grazing endophyte-infected fescue.

Males

Scrotum cannot cool testicles below body

temperature.

Temporary infertility that can last for up

to 60 days.

Shearing

Separate for feeding

Keep in cool place during day

Turn rams out at night only..

Cull rams susceptible to heat stress.

Females

Delayed heat cycles

Lower ovulation rates

Increased embryonic mortality

Shade, natural breezes

Do not work sheep in middle of day

Shearing

Breeding pastures

Phytoestrogens

Phytoestrogens are a diverse group of naturally occurring non steroidal plant compounds that, because of their structural similarity with estradiol have the ability to cause estrogenic or/and anti-estrogenic effects.

The major plants producing phyto-estrogens that are of importance to animal agriculture are legumes, clovers (subterranean and red) and alfalfa.

Can cause infertility and other reproductive problems.

Sheep most sensitive.

Ergot alkaloids

Kentucky 31 tall fescue is infected with a microscopic fungus commonly known as the endophyte.

There is evidence that the toxin produced by the endophyte can affect growth, reproductive, and lactation rates in small ruminants.

Inhibits prolactin production which could affect mothering response and inhibit lactation.

Crossbreeding to improve fertility

Average heterosis effects in the crossbred lamb (individual) 2.6%

Average heterosis effects in the crossbred ewe (maternal) 8.7%

Average heterosis effects in the crossbred male ?

Source: Nitter, 1978

Litter size (number born, prolificacy)

Ovulation rate (OR)

Number of eggs ovulated by

female.

Sets the upper limit for litter size.

Affected by breed, age, season,

genetics, and nutrition.

Embryo survival

Factors affecting embryo survival: breed type,

genetics, nutrition, and ovulation rate.

Embryo age % mortality

< 25 days 28

> 25 days 15

Each 20 days beyond 25 3-4

Total 43

Pregnancy Wastage, West Virginia University

How to increase litter size (number born)Ovulation rate + embryo survival

Management

Breed females when

they are in optimal

body condition.

If necessary, flush

females at beginning

and during early

part of breeding

season.

Good nutrition

during early part of

gestation.

Breed in fall.

Genetics Raise a more

productive breed, e.g. Polypay or Katahdin

Introduce a prolific breed, e.g. Romanov or Finnsheep.

Introduce FecB gene (Booroola Merino) into flock.

Heterosis via crossbreeding

Selection

Select breeding stock

from most productive

families.

If no other data is

available, select breeding

stock from large litters.

Select breeding stock

with high EBVs for

number born (NLB).

90 percent of the differences in litter

size are due to non-genetic factors

Season

Age

Nutrition

Static

Dynamic

SeasonSeason of breeding can have a large effect on lambing/kidding rates.

Sheep and goats are short-day breeders;

fall is their most natural time to breed.

Females bred in the fall will usually have

higher conception rates, ovulation rates,

and lambing/kidding percentages.

Females bred outside the “normal”

breeding season will usually have lower

conception rates, ovulation rates, and

lambing/kidding percentages.

A VA Tech Study showed that spring

lambing was consistently more profitable

than winter and fall lambing.

AgeAge (of female) has a large effect on litter size.

Virginia Tech study, using NSIP data from

Targhee, Polypay and Suffolk breeds (n=29,567)

Ewe age # of lambs

As compared to 4-7 (8) year old ewe

1 year old ewes - 0.6 – 0.7 lambs

2 year old ewes - 0.3 lambs

3 year old ewes - 0.1 lambs

> 7, 8 years - 0.21 lambs

As compared to 12 month old ewe

15 month old ewe lambs + 0.21 lambs

Body condition (BCS, 1-5)

Females in better body condition have

higher ovulation rates and higher

lambing/kidding percentages.

Conversely, over-conditioned females

(BCS >4.0) have reduced reproductive

performance.

Aim for a body condition score of 2.5

to 3.5 (depending upon production

system).

Access body condition of ewes/does

several months prior to breeding and

manage accordingly.

FlushingIncreasing nutrient intake and body condition prior to ( ovulation rates)

and during early part ( embryo survival) of breeding season.

Accomplished by providing ewes/does with fresh pasture, supplemental harvested forage, or up to 1 lb. of grain per head daily.

Response to flushing varies by age, breed, body condition, and stage of breeding season.

Mature > Yearlings

Less prolific > more prolific

Early > late

Thin > above average BC2-2.5 BCS > 3-3.5 BCS

Prolific breeds

With the exception of Suffolk, Rambouillet, Targhee and Finnsheep, few studies have been done to compare the prolificacy of different US sheep breeds.

Romanov and Finnsheep ewes have the highest prolificacy of any breeds, giving birth to 2.0 to 1.5 x as many lambs as Suffolk ewes (avg. 1.71).

Other breeds superior to Suffolk are Booroola Merino (with at least one copy of FecB+ gene), hair breeds, and Polypay.

With the exception of Angora goats, prolificacy of goats does not vary significantly among breeds and tends to be higher than most sheep.

Selecting for increased litter sizeH2 ~10%

Requires a long-term commitment: expect 1-2% improvement per year.

Select females that are more likely to produce multiple births and/or males that are more likely to sire prolific daughters.

Select for birth type or a composite trait, such as pounds of lamb/kid weaned.

Select replacements that are born as multiples from young mothers.

Select replacements from females who have demonstrated a lifetimeof multiple births.

Select replacements from same sex litters.

Enhancing selection with EBVs [via National Sheep Improvement Program (NSIP) -- for goats, too!]

An EBV is an estimated breeding value.

It is an estimate of an animal’s genetic worth.

It predicts differences in performance of offspring.

EBVs are calculated from the animal’s own performance, performance from genetically-related traits, and performance of relatives for those traits.

EBVs are calculated by Sheep Genetics (of Australia) via LambPlan. There is also a KidPlan.

Purebred or seedstock producers should consider enrolling their flocks and herds in NSIP. AS part of re-launch program, first year enrollment fee is being waived (up to 3 years for young producers, < 22 years).

Commercial producers should purchase males with desired EBVs.

nsip.org

Estimated breeding values are a proven

technology in other countries and animal

industries.

Targhee Katahdin

Lamb/kid survivalThere are many causes of lamb/kid mortality and many contributing factors.

Perinatal

Abortion

Diseases

Birth trauma/injury

Starvation

Exposure

Hypothermia

Pneumonia

Scours (diarrhea)

Predators

Pre-weaning Post-weaning

Diseases

GI problems

Coccidiosis

Nematodes (worms)

Predators

To improve survival, you need to

document the loss pattern.

Lamb and kid mortality usually

varies from 5 to 25 percent.

It varies by production system

and geographic location.

Losses are usually highest

during the first 48 hours after

birth.

Age %

First 24 hours 37.8

> 24 hrs, < 1 week 31.8

> 1 week, before weaning 30.4

Cause of death %

Scours 46

Starvation 20

Pneumonia 8

US Sheep Experiment Station

USDA APHIS NAHMS

Birth weight

Birth weight is a major factor affecting lamb/kid mortality.

In sheep, birth weights vary from 3.5 to 20 lbs.

Although these differences are associated with

breed, dam age, and litter size, they are highly

dependent on nutrition and in particular

energy intake during the last month of pregnancy.

Inadequate energy intake during this period will

result in lowered birth weights which in turn is

a major factor affecting lamb/kid mortality.

There may be as high as a 12 percent increase in

lamb mortality for every 2 pound decrease in lamb

birth weight.

On the other hand, excessive levels of feeding may result in lambs/kids

with increased birth weights leading to lambing/kidding difficulties.

Neonatal care: Clip, dip, strip, and sip

Clip: shorten navel cord with

scissors if necessary.

Dip: Spray or dip navel cord in

disinfectant, e.g. iodine or

chlorhexidine.

Strip: strip teats to remove wax

plugs and evaluate milk supply

Sip: make sure lambs/kids nurse

as soon as possible.

Crossbreeding to improve survival

Average heterosis effects in the crossbred lamb (individual) 9.8%

Average heterosis effects in the crossbred ewe (maternal) 2.7%

Average heterosis effects in the crossbred ram ?

Source: Nitter, 1978

Tips for improving perinatal lamb/kid

survival

Attended ewes/does at lambing/kidding

Shed lambing/kidding

Good hygiene: lamb/kid in a clean, stress-free environment.

Adequate shelter: well-ventilated, but draft-free

Control/eliminate diseases.

Vaccinations, as needed.

Have ewes/does in optimal body condition for lambing/kidding.

Do not underfeed or overfeed energy during late gestation.

Assist with difficult births, as needed.

Make sure lambs/kids consume adequate colostrum; assist, if necessary.

Use jugs to encourage bonding, especially for first-time moms.

Tips for improving pre-weaning

lamb/kid survival

Adequate colostrum intake.

Good nutrition to maintain milk supply.

Vaccinate pregnant females for clostridial diseases: CDT or 7,8-way

Other vaccinations as necessary.

Include a coccidiostat in feed or mineral.

Control predation: fencing, guardians, night penning, shooting, trapping, denning etc.

Cull poor mothers.

Select for number weaned or pounds of lamb/kid weaned.

Tips for improving post-weaning

lamb/kid survival

Vaccinate lambs/kids for clostridial diseases once colostridialimmunity starts to wane.

Deworm pregnant females to control periparturient egg rise: primary source of infection for lambs and kids grazing summer pastures.

Integrated parasite management: pasture rest/rotation, alternative forages, multi-species grazing, and targeted selective treatment.

Test for anthelmintic resistance.

Good nutrition to ensure good growth rates and disease resistance.

Feed balanced rations, e.g. Ca: P of >2:1

Avoid digestive disturbances, e.g. acidosis, bloat.

Control predation: fencing, guardians, night penning, shooting, trapping, denning etc.

Importance of sire selection

Most genetic improvement is made through the male.

The male contributes half the genetics to the flock or herd.

There are considerable differences among breeds and sires for maternal traits.

It is more difficult to make genetic improvement in maternal traits, as they are less heritable and are not expressed in the male.

NSIP provides the means to evaluate maternal traits in sheep and meat goats, especially males.

Thank you for your attention. Questions, comments?

SUSAN SCHOENIAN

SHEEP & GOAT SPECIALIST

UNIVERSITY OF MARYLAND EXTENSION

[email protected] – WWW.SHEEPANDGOAT.COM