This document discusses different group breeding schemes used for genetic improvement, including Open Nucleus Breeding Systems (ONBS) and Closed Nucleus Breeding Systems (CNBS). ONBS involves bidirectional gene flow between the nucleus herd and lower herds, while CNBS only allows upward gene flow from lower herds to the nucleus. Cooperative group breeding systems run ONBS cooperatively between farmers for increased selection intensity. The actual genetic gain depends on selection pressure and exchange rates between herds. Multiple Ovulation and Embryo Transfer techniques can also be used in nucleus schemes to further reduce generation intervals.

1. Topic:
Group Breeding Schemes
- ONBS
- CNBS
Dr S.Shanaz
Division Of AGB

2. Group Breeding Schemes
 Screening to identify superior individuals ; helpful in establishing a central
nucleus
 Genetic improvement by further selection based on measured production
 A nucleus herd is created, used entirely for production of males for
breeding in a population
 Two types of Nucleus breeding schemes also called GBS on the basis of
direction of gene flow
 GBS is the interest of all its members to secure the highest possible genetic
level and the highest rate of genetic progress for the nucleus
 Farmers motive: to contribute superior females to the nucleus and to get
elite bull
 Rate of genetic progress may thus be increased by a further 10 – 15%.

3. OPEN NUCLEUS BREEDING SYSTEM
• ONBS concept comprises a nucleus herd established under
controlled conditions to facilitate selection
• Nucleus is established from the best animals selected from the base
population
• Recorded individually and the best animals are selected to form the
elite herd of nucleus
• Two way direction of gene flow downward from nucleus to lower
herd (multiplier and commercial) and upward from lower herd to
upper herd (nucleus) by introduction of superior animals from other
herds

4. • Elite females and superior sires are mated , the offsprings
are reared, recorded and the males among them are
evaluated
• Elite group of males with high breeding values can be used
in the farmers herd for genetic improvement
• Greater genetic improvement can be made in large
population of cattle and buffaloes in their home tract
Need: ONBS should be effected in different regions to
monitor and augment the production performances of
different breeds of cattle and buffaloes in India

5. A) NUCLEUS TIER
• Composed of top parental breeding stock (consists of 10 – 15% of
breed population , selected exclusively on their breeding value
• This tier acts as selector and supplier of replacement male and
female breeding stock for itself and for multiplier tier at farm level
and commercial tier at field level
• Stationed at a particular place with all necessary inputs of land,
feed, labour and favourable environment.
STRUCTURE OF ONBS

6. B) MULTIPLIER TIER
• This is constituted by about 30-40 percent of breed population
• Acts as multiplier and tester population
• It exclusively receives stud males and sometimes breeding
females from the nucleus herd
• sole purpose is production of sufficient number of breeding
animals to satisfy the demands of herds in the commercial tier

7. Commercial tier
• It has 40 – 60 percent of breed population and is generated using
males and females , produced under multiplier herds
• The intention is to increase the production and the genetic
improvement
• It acts as terminal tier of hierarchical breeding structure
• ONBS concept involves introduction of superior quality females to the
sire breeding nucleus, like semen stations from other tiers of
breeding
• Inspite of high selection intensity and advent of AI and frozen semen
technology , the expected genetic gain is limited
• Overcome by ONBS to some extent where both males and females
contribute to the total annual genetic gain
• The expected genetic gain may be increased by 10 – 15 per cent.

8. CNBS Vs ONBS
• Direction of the gene flow in CNBS is always one sided i.e
nucleus tier  multiplier commercial tier
• Generally superior breeding females – daughters born to sires of
nucleus tier in the multiplier or commercial tier are selected based
on their genetic merit and breeding values
• These are transferred to the nucleus tier for breeding as replacer
• Nucleus tier has bulls selected based on their pedigree: Best bulls are
selected based on their genetic superiority and used for producing
best animals
• The females from commercial tier are selected based on their genetic
merit and transferred to multiplier herd and nucleus tier for breeding

9. • The nucleus tier is opened for the receipt of elite females
from the downward tiers as replacer
• ONBS raises the possibility of introducing commercially
bred, non pedigreed animals into pedigree herds of nucleus
• Improvement lag is less due to bidirectional gene flow in
ONBS
• Major disadvantage is the disease control in ONBS
CNBS Vs ONBS
 Breeders maintain their units under closed breeding system
by adopting strict quarantine and biosecurity measures

10. COOPERATIVE GROUP BREEDING SYSTEM (CGBS)
• ONBS run in an organized (pedigreed )herd at institutional (govt.) farm or
by breed societies  Cooperative Breeding Scheme
• Majority of farmers usually maintain only one or two cows or buffaloes
Maximum selection intensity can be achieved by cooperative breeding
systems especially in dairy sector
• Requires close cooperation between breeders
• NDDB and state level Milk federations have already established bull
mother farms and they are in the process of procuring young bull calves
born to elite cows under field conditions and raising them as future
breeding bulls
• In principle the CGBS adopted a sire breeding nucleus to breed
replacement sires for itself and the associated field level herds. Cows or
buffaloes replacements are reared in both the nucleus and associated
herds at field level

11. Actual genetic gain depends upon:
 High selection pressure applied on initial screening of
both cows and bulls
 Population size
 continuation of selection of cows and bulls within the
nucleus
 Exchange rate of females and males from the
contributor herds and nucleus unit
Genetic gain

12. NBS using MOET or MOET Nucleus Scheme
• NBS can be run with or without using MOET
(Multiple Ovulation and Embryo Transfer)
• When MOET is used in NBS it is called MOET Nucleus Schemes
• Composite technology ,involves multiple processes
 Super ovulation
 Estrus synchronization of recipients
 A.I of the donor
 Embryo recovery from the donor
• Advantage is reduction in generation interval by way of selecting
siblings and no daughters
• Accuracy is less but is outweighted by reduction in G.I

13. Variants or Types of MOET Nucleus Schemes
 Juvenile MOET:
• Selection of bulls and cows is done at an early age before first breeding
• Selection criteria is dams’ ancestors and sibs of dams and sires records
• GI is less
 Adult MOET:
• Males are selectek6d on ancestors records plus their full and half sisters
records
• females selected on the basis of ancestors plus their own sibs and their
own performance,
• GI is longer
• Mixed or Hybrid MOET:
• PT of males is required for nucleus replacement
• Mixed MOET can be juvenile mixed MOET or adult mixed MOET