Possible Physiological Benchmarks for Sow Longevity prior to Puberty

W.L. Flowers

North Carolina State University

Raleigh, N.C.

Developmental Period

It would be useful if there were things we could measure during the

developmental period that provide us with some idea of the longevity potential

of prospective replacement females.

The period just prior to birth is an active period offetal growth and ovarian development.

Birth weight is positively correlated with organdevelopment.

0.24

0.20

0.16

0.12

0.08Org

an W

eigh

t (lb

s)

0 1.0 2.0 3.0 4.0

Birth Weight (lbs)

Relationships between Piglet Birth Weights and Organ Weights

0.00

(Adapted from Foxcroft et al., 2009)

Small Intestines

Liver

Brain

Some aspects of fetal developmentprobably respond the same way to competition

as pig growth in “crowded pens”.

6 developing fetuses12 developing fetuses

Birth weight probably is also positively related tothe development of reproductive organs.

Piglet Birth Weight (lbs)ReproductivePerformance 2.0 – 2.8 > 3.5

Age at puberty (days) 188 + 8 170 + 6

Ovulation rate 12.9 + 0.6 15.3 + 0.7

Embryonic survival (%) 69 + 7 83 + 6

Birth Weight and Reproductive Performance of Gilts

(Flowers, unpublished)

Birth Weight and Longevity from Neonatal Study

• Study was conducted with 1820 gilts in an 80,000 sow commercial production system.

• Only used litters that had between 10 and 14 pigs born alive.

• Litter size was adjusted after birth to either < 7 pigs (n=899) or > 10 pigs (n=921).

• Examined birth weight categories in only the sows that nursed > 10 pigs (n=921)

Fe

ma

les

rem

ain

ing

in p

rod

uctio

n (

%)

E = EntryB = Breeding - gilts F = FarrowingR = Rebreeding

Effect of Replacement Gilt Birth Weight on Sow Longevity

90

(Flowers, unpublished)

80

70

60

50

40

30

20

10

F1

100

0

R1 F2 R2 F3 R3 F4 R4 F5 R5 F6E B

Production phase

2.6 - 3.5 lbs

< 2.5 lbs

> 3.6 lbs

There probably is a minimum birth weight below which gilts simply don’t have the reproductive machinery to function adequately as adults no matter how well they are managed subsequently.

While most of the follicles on the ovaries are presentat birth they begin to acquire their functional competence during the next 30 days – most of whichoccurs during their nursing period.

WeaningBirth(Morbeck et al. 1993)

Producers have very little control prospectively over birth weight, but

can affect pre-weaning growth.

Effect of Neonatal Litter Size on Sow Longevity

• Study was conducted with 1820 gilts in an 80,000 sow commercial production system.

• Only used litters that had between 10 and 14 pigs born alive.

• Litter size was adjusted after birth to either < 7 pigs (n=899) or > 10 pigs (n=921).

• Commercial farm used pen gestation and had average birth weights less than 3 lbs.

< 7 pigs nursing> 10 pigs nursing

Cross sectionof ovaries from a 17-day old gilt fromlitter of < 7 pigs

Cross sectionof ovaries from a 17-day old gilt fromlitter of > 10 pigs

Fe

ma

les

rem

ain

ing

in p

rod

uctio

n (

%)

E = EntryB = Breeding - gilts F = FarrowingR = Rebreeding

Effect of Neonatal Lactation Litter Size on Sow Longevity

90

(Flowers et al., in press)

80

70

60

50

40

30

20

10

F1

100

0

R1 F2 R2 F3 R3 F4 R4 F5 R5 F6E B

Production phase

p < 0.05*

** * * * * * *

**

< 7 piglets

> 10 piglets

Far

row

ing

rate

(%) 90

80

70

60

2

100

0

3 4 5 61

Sow ParityN

umbe

r Bor

n A

live

11

10

9

2

12

0

3 4 5 61

Sow Parity

> 10 piglets (10.5 + 0.2)

< 7 piglets (11.0 + 0.1)

p < 0.07

> 10 piglets (83.3%)

< 7 piglets (88.7%)

p < 0.05

Reproductive Performance and Neonatal Litter Size

Reducing competition during the neonatal periodenhances early ovarian development which improvedlongevity.

What can we measure during this period to accuratelyassess growth and development of gilts?

Growth Measures R2 P value

Weaning weight (lbs) 0.06 ( 6%) 0.14

Association of Growth Characteristics with Longevity

(Flowers, unpublished)

Growth Measures R2 P value

Weaning weight (lbs) 0.06 ( 6%) 0.14

Pre-weaning gain (lbs) 0.14 (14%) 0.04

Association of Growth Characteristics with Longevity

(Flowers, unpublished)

Growth Measures R2 P value

Weaning weight (lbs) 0.06 ( 6%) 0.14

Pre-weaning gain (lbs) 0.14 (14%) 0.04

Pre-weaning gain / birth weight

Association of Growth Characteristics with Longevity

(Flowers, unpublished)

Pig A Pig B Pig C Pig D

Birth weight (lbs) 2.5 2.5 3.5 3.5

Weaning weight (lbs) 16.5 22.5 16.5 17.5

Pre-weaning growth (lbs) 14.0 20.0 13.5 14.0

Pre-weaning growth / 5.6 8.0 3.8 4.0birth weight

Pre-weaning gain / birth weight

Growth Measures R2 P value

Weaning weight (lbs) 0.06 ( 6%) 0.14

Pre-weaning gain (lbs) 0.14 (14%) 0.04

Pre-weaning gain / 0.22 (22%) 0.001

birth weight (%)

Association of Growth Characteristics with Longevity

(Flowers, unpublished)

So

ws

that

pro

du

ced

6 li

tters

(%

)Interactions between Birth Weight and Neonatal Litter Size

(Flowers, unpublished)

40

30

20

10

50

0

2.6 – 3.5 lbs > 3.6 lbs< 2.5 lbs

Birth Weight Categories

> 10 piglets

< 7 piglets

p < 0.05

*

*

*

Growth Measures R2 P value

Weaning weight (lbs) 0.06 ( 6%) 0.14

Pre-weaning gain (lbs) 0.14 (14%) 0.04

Pre-weaning gain / 0.22 (22%) 0.001

birth weight (%)

Total Growth 0.42 (42%)

Other factors 0.58 (58%)

Association of Growth Characteristics with Longevity

(Flowers, unpublished)

Pre-weaning growth and pre-weaning growth relative to birth weight appear to have positive associationswith sow longevity and lifetime productivity

The best physiological test for longevity would besomething that mimics what the mature sow asked required to do effectively each parity.

LH, FSH

Estrogens

+

0 5 10 15 20 25 30 35 40 45 50 55 60

Nu

mbe

r of

Gilt

s in

Est

rus 50

40

30

20

10

0

Days from Onset of Boar Exposure

0 5 10 15 20 25 30 35 40 45 50 55 60

Nu

mbe

r of

Gilt

s in

Est

rus 50

40

30

20

10

0

Days from Onset of Boar Exposure

Boar Exposure140 days

Boar Exposure170 days

220140 160 180 200

Effect of Neonatal Environment on Female Response to Early Boar Exposure

Neonatal Environment

Variables < 7 pigs > 10 pigs

Proportion of gilts in estrus 77.0 53.028 days after exposure (%)

Average number born 11.3 10.8alive – early responders

Average number born 10.3 10.2alive – late responders

(Flowers et al., in press)*

*

†

†

p < 0.08p < 0.05

Fe

ma

les

rem

ain

ing

in p

rod

uctio

n (

%)

E = EntryB = Breeding - gilts F = FarrowingR = Rebreeding

Effect of Neonatal Lactation Litter Size on Sow Longevity

90

(Flowers et al., in press)

80

70

60

50

40

30

20

10

F1

100

0

R1 F2 R2 F3 R3 F4 R4 F5 R5 F6E B

Production phase

p < 0.05*

** * * * * * *

**

< 7 piglets

> 10 piglets

22%

0 5 10 15 20 25 30 35 40 45 50 55 60

Nu

mbe

r of

Gilt

s in

Est

rus 50

40

30

20

10

0

Days from Onset of Boar Exposure

0 5 10 15 20 25 30 35 40 45 50 55 60

Nu

mbe

r of

Gilt

s in

Est

rus 50

40

30

20

10

0

Days from Onset of Boar Exposure

Boar Exposure140 days

Boar Exposure170 days

220140 160 180 200

LH, FSH

Estrogens

Gilt

s ex

hib

itin

g vu

lvar

sw

elli

ng (

%)

Effect of Neonatal Litter Size on Response to PG600

80

60

40

20

100

100

0

120 140 16080

Age of gilts (days)

> 10 piglets

< 7 piglets

p < 0.05

*

* *

*

Positive responseat 140 days of age

No responseat 140 days of age

Strategic use of commercially available gonado-tropins might be a way to screen for gilts capableof early puberty without using a boar.

Developmental Period

Graduate Students Undergraduate StudentsDr. Jean Popwell Dr. Chad Smith

Dr. Lauren Job

Dr. Brad Belstra Dr. Patrick O’QuinnJennifer Griffin Dr. Catherine HefleyDr. Kara Stewart Dr. Kyle Lovercamp Dr. Lisa Thompson Frances Turner Kristey Kenney

Sara Shute Nikhol GarbacikShelley Swing Stefani Garbacik

151413121110

98

0

Num

ber

Bor

n A

live

10 20 30 40 50

Litter Birth Weight (lbs)

Relationship between Number Born Aliveand Litter Birth Weights

151413121110

98

0

Num

ber

Bor

n A

live

10 20 30 40 50

Litter Birth Weight (lbs)

Number Born Alive and Litter Birth Weights

2.5 lb birthweight

Market animals ?

PotentialReplace-ment gilts

151413121110

98

0

Num

ber

Bor

n A

live

10 20 30 40 50

Litter Birth Weight (lbs)

Number Born Alive and Litter Birth Weights

2.5 lb birthweight

Replace-ment gilts

3.6 lb birthweight

StrategicCrossfostering

Developmental Period

Periodic assessmentof managementduring development.