Open Nucleus Breeding System in Dairy An

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College of Veterinary Science & A.H., S.D.A.U, Sardarkrushinagar “Open Nucleus Breeding System in Dairy Animals” Presented by: Dr. Dhiren B. Bhoi M.V.Sc. Veterinary Gynaecology and Obstetrics E. Mail:-drdhirenvet@gmail.com

Introduction : 

Introduction Animal husbandry is an integral part of farmers livelihood With growth in human population, increased in livestock products is inevitable With traditional wisdom of farmer many breeds of dairy animals were developed. Livestock improvement programmes (GOI)

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These breeding programmes contribute significantly to improving livestock production efficiency. Awareness of health of dairy animals Improved dairy animals through adequate selection that sustained local breed to secure genetic resources. Livestock Breeding System (traditional).

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From mid sixties onwards, GOI (1961) – Crossbreeding Generated lot of controversy. Genetic instability of crossbred animals. Non-adaptability to local agro-climatic conditions. Poor draft capacity. Non-availability of superior crossbred animals. Progeny Testing programmes long time it takes to secure the results of performance of the progeny. Low genetic gain

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To increase the overall genetic merit of the breed nucleus breeding systems are used. Cooperative breeding system (nucleus) was alternative to traditional breeding system which based on principles as Farmers record their herd top female send them to one unit forming nucleus managed by farmers committee open highly productive female selected males used as replacement in the cooperating farms In these, the group of farmers was agreeing to pool their high performing animals.

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The best males were kept for breeding in nucleus while other selected males were given to the base herds for breeding. The nucleus remained open to animals from the base herds and the best females from the latter being admitted periodically and compared with those in the nucleus. Only females were transferred from the base to the nucleus. So, genetic superiority of sire replacement coming into base from nucleus was greater than base herds.

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Open nucleus breeding system in sheep industry . (Roden, 1994) Organized and Village herd Open nucleus breeding system has two way flow of gene as compared to closed nucleus by introduction of superior animals from other herds.

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Reduces the rate of inbreeding in nucleus herd and increase the genetic progress. In ONBS, Sire mother milk > 20% milk production. Flock size (Small) Sizable nucleus 2-3% gain

Historical Aspect : 

Historical Aspect

Nucleus Breeding System : 

Nucleus Breeding System A cooperating breeding programmes in which elite animals are concentrated in nucleus herd/flock & superior germ plasm has then distributed among cooperative herd/flock to nucleus (Richard Bourdon, 1980) Nucleus breeding system----- Open & Closed [gene flow] Breed structure Breed structure can be modified to increase the overall genetic merit of the breed and the new concept of nucleus breeding has been developed

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N M C (Nicholas, 1987) A typical breed structure consists of 3 tiers in the shape of pyramid. Selection & Replacement Breeding males & female Female progeny Male progeny Replacement

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Two tier structure N B N M Commercial A multi tier breeding structure with selection in nucleus and multiplier levels and possibly upward migration of genetic material

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(Roden, 1994) Replacement Stock N B N B CLOSE OPEN

Closed Nucleus System : 

Closed Nucleus System As in the traditional pyramid, there was one way flow of genes, downward from top to bottom. Source of cumulative genetic progress in commercial population was improvement occurs in the nucleus populations. Rate of inbreeding increased and overall genetic gain fluctuate (Nicholas, 1987) Pig & Poultry

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Rate of inbreeding in ONBS = 2 CNBS (James, 1977)

Open Nucleus Breeding System : 

Open Nucleus Breeding System Gene flow from both way viz., downward from nucleus to other lower herd (multiplier & commercial) and upward from lower to upper herd (nucleus) by introduction of superior animals from other herds. Rate of inbreeding reduces and genetic progress increases as superior animals were available with farmers. Cattle, Buffalo, Sheep and Goat. (Nicholas, 1987)

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CENTRAL NUCLEUS Female Top 2% Male Female Top 1% 10,000 EWES Ram Breeding Co-operatives 120,000 ewes Contributors flock 2,000,000 Open nucleus breeding system in Merino Sheep

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The ONBS can be useful in the developing countries where herd or flock size is small. ONBS can lead to a 10-15% increase in annual response to selection which substantially reduce the rate of inbreeding in the nucleus (Nicholas, 1987) Shortest generation interval. (Meuwissen, 1991) ONBS was also accompanied with multiple ovulation and embryo transfer (MOET) which maximize the annual genetic gain. (Dixit and Sadana, 1999)

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To increase the rate of genetic response in dairy cattle MOET nucleus schemes used. (Nicholas & Smith, 1983) MOET augment reproductive potential of donor female & formed embryo transferred to recipient which are of low genetic gain (Ruane, 1988) Elite herd of male & female G.I. reduced for reason of sibling test for selection which lower the accuracy of selection Selection & testing in nucleus herd (controlled environment)

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MOET Nucleus Schemes Juvenile MOET Adult MOET Mixed MOET Early age before first breeding & less G. I. Male:- ancestor performance + full & half sisters records Female:- ancestor performance + their own sib & own performance Longer G. I. Progeny tested sires used nucleus replacement Short G.I Juvenile & Adult Mixed MOET

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Development of MOET technology which enables to increase reproductive rate of cow (Ruane, 1988) MOET are relevant where PT scheme not feasible (McGuirk & Seidel, 1992) High selection intensity applied to females which make shortest generation interval. MOET in ONBS as an alternative to conventional PT for evaluation of bulls and bull mothers (Trivedi et al., 2004)

Principal Factors : 

Principal Factors 1. Nucleus Size:- Optimum nucleus size is a function of the ratio of selection intensities in males and females. (James, 1976) In cattle and sheep populations the highest rate of genetic gain was achieved when nucleus size has 5-10% of the population. (James, 1977)

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As female selection intensity decreased and male selection intensity increased, the optimum nucleus size decreased. (James, 1977) At smaller nucleus sizes more generations are required. (Muller and James, 1983)

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2. Migration Rate:- Migration rate determination [B.V.]. (Shepherd, 1991) Migration rate vary over selection period to maximize the response. Upward female migration rate was favoured longtime if short-term selection response was to be maximized. (Del-Bosque Gonzalez, 1989)

Optimization of ONBS Structure : 

Optimization of ONBS Structure To maximize genetic gain and financial returns. Criteria for Optimization:- Rate of Inbreeding Effective population size of nucleus Genetic gain Economic returns

Models of ONBS : 

Models of ONBS Jackson & Turner Model [1972] Evaluate various structure in ONBS Gene flow and genetic differences between base and nucleus population Genetic selection differential Annual genetic gain

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James Model [1977] System operate over two tiers Truncation Migration rate constant over time Genetic lag & annual rate of genetic gain to constant equilibrium values. Rate of genetic change selection, migration & genetic lag Effective size of population = 2 [size of nucleus]

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Hopkins & James Model [1977] Overlapping generations Discrete generation Parental selection/Sequential culling Migration rate optimizing genetic selection differential [never fixed overtime] Similar model used in Dairy Cattle (Meuwissen,1991)

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Muller & James Model [1983] Extended James model linkage disequilibrium change in genetic variance Genetic variance constant (assumption) Contradiction of assumption; if loss occurred Shepherd & Kinghorn Model [1992] Migration rate Truncation Selection on estimated B.V. Parental age groups Optimization of system with EBVM as with constant migration method of James (1977) In 1993; Model of two tiers, Selection BLUP & Migration EBVM

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Various Aspects of ONBS

Kind of ONBS in Dairy cattle : 

Kind of ONBS in Dairy cattle (Cunningham, 1979)

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250 elite buffalo 32 top buffaloes selected 8 sire 16 embryos recovered per buffalo 8 successful Pregnancies (4 male & 4 female) 128 male 128 female (Trivedi, 1989) A Model of ONBS in Buffalo

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Phase I Phase II Nucleus of Sahiwal cow 24 top cow + 6 cow 1 H.F. 3 female & 3 male (18 female & 18 male) 4 male 4 male + 18 CB female Inter-se mated male & female calves 3 top F2 & 1F1 male + 18 CB female Top Sahiwal cow 3-4 pure H.F. bulls A ONBS model at SAG (Trivedi et al., 2004)

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(Philipson et al., 2006)

Advantages of ONBS : 

Advantages of ONBS Complementing genetic improvement programmes and increased overall rate of genetic gain Reduces rate of inbreeding and increased progress. Provides degree of control on determinates of genetic changes High rate of genetic progress As ONBS has operated in small herd, recording of data becomes very reliable

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Possible to record data on FCE, reproduction efficiency, disease resistance, body confirmation etc. which are not easy to record in P.T. programmes Versatility It hold the promises to enhances milk production as well as socioeconomic status of farmers

Conclusions : 

Conclusions Open nucleus breeding activities could be the best compromise in the developing countries like India for genetic improvement in dairy animals ONBS would be best vehicle to introduce newer animal biotechnologies such as embryo sexing, embryo cloning, gene transfer etc. Overall higher genetic merit through ONBS is expected (3-5%) in comparison to traditional livestock breeding system (0.5%) It offers two way gene flow It also offers conservation of genetic resources & upgrading of local population

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THANKING YOU !