3- Quản lý và nâng cao năng suất Dê cái sinh sản? (Tham khảo tại đây)

Three types of devices are available: cronolone (20mg) impregnated sponges (Chronogest CR, MSD AH), MAP (60mg) impregnated sponges and CIDR (0.3g). Typical treatment schedule[r]

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Reproductive management in

small ruminants

Feb 2012 M.A Driancourt, MSD AH, R&D Pharmaceuticals

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Backbone of the presentation

1 What are the main reproductive features of Middle East sheep and goat breeds?

2 What are the consequences on these physiological features on

production?

3 What are the technical options to break seasonal anoestrus?

4 What are the technical options to synchronize estrus during the

breeding season?

5 How can we improve fertility?

6 How can prolificacy be improved?

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What are the main reproductive features of

Middle East sheep and goat breeds?

Awassi sheep

• Display a seasonal pattern of

reproduction

• Tend to display a late puberty

• Commonly produce a single lamb

(low prolificacy)

• Are good milk producers

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Damascus goats

• Display a seasonal pattern of

reproduction, with a variable

breeding season (June to Oct

in Jordan or Sept to Feb in

Cyprus)

• Tend to display a late puberty

• Are mildly prolific (1.5 kid per

litter)

• Are good milk producers

(500kg/lactation)

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Links between month of the year and cyclicity in sheep and goats

Month of the year

Less seasonal breed or female anoestrus BS

BS Transition Transition

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What are the consequences on these

physiological features on

production?

The seasonal pattern of reproduction does not allow to have

reproduction timed to generate milk or lamb meat when prices are highest

The seasonal pattern of reproduction may not always fit with the

periods when forage and feedstuffs are available to cover the

production needs of the late pregnant and lactating ewes or the

growth needs of the lambs

Low prolificacy negatively affects the income of the farmers

The random pattern of cyclicity between individual ewes of a flock does

not allow to use AI (and the associated diffusion of genetic merit)

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What are the consequences on these

physiological features on

production?

• Breed during anoestrus (hence “break” anoestrus)

• Synchronize estrus during the breeding season (to use

AI )

• Increase prolificacy

Technical needs triggered by these physiological features

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What are the technical options to break

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seasonal anoestrus?

• Use progestagen/progesterone impregnated vaginal devices

Three types of devices are available: cronolone (20mg) impregnated

sponges (Chronogest CR, MSD AH), MAP (60mg) impregnated sponges and CIDR(0.3g progesterone)

Typical treatment schedule

Sponge

insertion removal and Sponge

PMSG injection

AI or mating

55h

SHEEP

If mating is used, preparation of the rams (flushing, light treatment or melatonin) and a suitable ewe to ram ratio are needed

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seasonal anoestrus?

•Use progestagen/progesterone

impregnated vaginal devices (+ 400IU

PMSG and mating) in Awassi ewes

SHEEP

Ozyutlu et al 2010

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seasonal anoestrus?

sponges (Chronogest CR, MSD AH), and CIDR

Bucks also need to

be prepared!

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50.9%

500UI PMSG

62.9%

600UI PMSG

68.1%

Prolificacy= 1.97+/- 0.8

Fertility Alpine & Saanen goats

Intervet registration files

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seasonal anoestrus?

• Use the ram effect

Pre-requisites:

during the transition period

for at least a month

treatment/melatonin)

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seasonal anoestrus?

• Use the ram effect

Chemineau et al 2006 Estrus and formation of normal corpora lutea do not

happen immediately!

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(Gomez et al 2006), Manchega ewes

I Implants need to be inserted between 50 and 70 days before breeding

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What are the technical options to synchronize estrus during the breeding

season?

• Use progestagen/progesterone impregnated vaginal

devices

• Use of Ovsynch type protocols

• Use of double prostaglandin protocols

SHEEP

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season?

Three types of devices are available: cronolone (20mg) impregnated sponges (Chronogest CR, MSD AH), MAP (60mg) impregnated sponges and CIDR (0.3g)

Sponge

insertion removal and Sponge

PMSG injection

AI or mating

55h

SHEEP

If mating is used, a suitable ewe to ram ratio

needs to be respected

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Dairy (Manech)

Meat (Texel, Vendeen) Fertility 71% 52.3% 63.2%

Prolificacy 1.69+/- 0.67 1.45+/- 0.77 1.62+/-0.68

Intervet registration files

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season?

Sponges allow to obtain improved reproductive performance in Awassi ewes

managed in a “3 lambings in 2 years” management system (6 breeding

periods)

SHEEP

Zarkawi et al 2011

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sponges (Chronogest CR, MSD AH), and CIDR

What are the technical options to synchronize estrus

during the breeding season?

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50% fertility in Greek ewes

60% fertility

in Awassi ewes

GnRH PGF2 a Rams in

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season?

•Use of Ovsynch type protocols

(Holtz et al 2008) Boer goats GOAT

N=24/group Sponge

+ prostaglandin and 250IU PMSG 48h before sponge removal (AI 43h

later)

Ovsynch

( 4µg Buserelin on d0, prostaglandin on d 7 and 4µg buserelin on d 9 with

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season?

•Use of double prostaglandin

protocols ( 7 to 11 days apart)

SHEEP

control Double PG

Conception (% US positive 30 days

post AI)

Prolificacy 1.58 1.27

Fierro et al 2011

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season?

• Vaginal sponges are the best approach

• Ovsynch may be an alternative in goats

• Double prostaglandin treatment reduces fertility

Take home message

When a successful synchronization is obatined,

1 Diffusion of genetic merit becomes possible (AI)

2 Breeding can be focussed on a narrow part of the year (labor efficiency)

3 Lambing is limited to a narrow time period (labor efficacy)

4 An homogeneous lamb crop is ready to be sold at a set time every year

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How can we reach optimal prolificacy?

What is optimal prolificacy?

• An homogeneous crop of twins! (no triplets)

• If

1 maternal behavior of the ewe is OK!

2 Milk production of the ewe is adequate!

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How can prolificacy be improved?

• Use PMSG at removal of progestagen/progesterone

impregnated vaginal devices

• Use Androvax, a vaccine against an ovarian steroid

• Use genetic introgression of a prolificacy gene (such

as Fec B) into your sheep breed

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•Use PMSG at removal of progestagen/progesterone

impregnated vaginal devices

Dose of PMSG (IU)

Ovulation

rate

Quirke et al 1986

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The recommended vaccination schedule is First vaccination (2ml): 8 to 10 weeks before joining Booster (2ml): 4 to 6 weeks before joining

The antibodies reduce negative feedback of the steroids on LH secretion The increased frequency of LH pulses increases the proportion of double ovulations (by around 20%)

Not affecting seasonality (not inducing ovulation in anoestrous ewes) Not synchronizing ovulation, hence compatible with mating by rams

A booster is needed every year to obtain the prolificacy increase, but may be skipped if

A vaccine against a steroid (androstenedione coupled to a carrier (bovine lactalbumin) in

a DEAE adjuvant), applied as a primary and a booster on the first year of treatment.

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Prolificacy data from 27 farms in NZ

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• Use genetic introgression of a prolificacy gene (such

as Fec B) into your sheep breed

The Booroola gene (Fec B) is a major gene that has large effects on prolificacy (but not on seasonality)

Homozygous ewes and heterozygous carrier ewes display over 5 and around 3 ovulations (vs 1 for the non carriers)

This gene acts by interfering with the signalling of bone morphogenic proteins Its position in the sheep genome is known

By crossing a specific breed with homozygous rams and then backcrossing to the initial breed, it is possible to introgress the Fec B prolificacy gene in that breed, while keeping all the production features of the breed (was done with Awassi)

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How should fertility problems be analysed?

Questions to be asked when fertility is lower than expected

1 Is the problem physiological or pathological?

2 What evidence do I have that low fertility is only a

female problem?

3 What evidence do I have that the ewes were indeed

ready to be bred (i.e cycling)

4 Was body condition of the ewes adequate for initiation

and maintenance of pregnancy?

5 What were the climatic conditions in the days around

ovulation and early embryonic development?

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Conclusion : the tools to work from…

Efficient breeding at all times of the year

Improving prolificacy Allowing early

breeding of ewe lambs

Allows easy diffusion of genetic merit

by AI

Allows matings by rams

10-40%)

(depending on amount of PMSG)

ratio adapted to the season)

Melatonin

Genetics Not yet If prolificacy

genes are introgressed

Improved

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Conclusion: how to implement these

tools according to your needs

• There are many tools that are available to move from

extensive production systems towards more intensive

ones (provided the farm technical management and food availability allow it)

• Several steps of intensification are possible (from mild such as the use of Androvax or melatonin implants to a more “European” production system using sponges to obtain three lambings in 2 years with increased

prolificacy)

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Questions?

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