Bolet, G

Felgines, C

Genetics Selection Evolution

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G Bolet

C Felgines

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SESSION VI
COURTES COMMUNICATIONS ET SÉANCE DE TRAVAIL
The genetic principles of the continuous hybridization programme
J. KARPATI
Kaposvar, Kanizsai u. 72, 7400, Hungary
In the beginning, in the 1950’s and 1960’s the tone ruling international literature
was there are no possibilities for producing hybrids in swine breeding, in contrast to poultry
breeding. Since that time more and more experience proved what we can lose by purebred
breeding. This breeding method, the continuous pig hybridization shows the most econo-
mical way for the goal.
The basic principles of this kind of hybridization : the male line is bred by close
inbreeding creating inbred lines, the sows are selected from the «hybrid end product »
through a selection process conducted under high genetic pressure to form the next mother
generation. In every single case they receive the most suitable male partner based on test
mating.
Maternal and grand-maternal effects on litter size in pigs
G. NITTER, P. ZINSMAIER, Andrea CZAP H. HAUSSMANN
Institut fiir Tierhaltung und Tierziichtung, Univ. Hohenheim
D - 7000 Stuttgart 70
Two sets of data were available for an investigation of genetic parent-offspring
relationships in pig fertility. These were the records of selected lines in a University farm
and herdbook data in Baden-Wfrttemberg. Regressions of daughters’ litter sizes were cal-
culated separately on their litter of origin and on independent litters of their dams. Further-
more, on a small number of records daughter-granddam regressions could be presented. A
comparison of heritabilities derived from these different types of regression partly revealed
some evidence of the existence of maternal effects on litter size as originally shown in
mice by FALCONER (1965). The insufficiency of this type of analysis was discussed for the
problem raised which is particularly relevant in herdbook data.
Heritability of litter size, phenotypic and genetic correlations between
the four first litters of Large White sows
G. BOLET C. FELGINES
Station de Ggntique quantitative et appliquee, LN.R.A.
F 78350 Jouy-en-Josas
Data from 76 purebred Large White herds from 1965 to 1979 were used to estimate
genetic parameters of litter size characteristics (number of piglets born &mdash; NB -, born alive
- NA &mdash; and weaned - NW -) using the daughter-dam regressions for the parities 1 to 4
(21 538 data). Heritabilities go from to 0.01 to 0.12. Genetic and phenotypic correlations
between NB, NA and NW within each parity are very high, from 0.7 to 1. Genetic corre-
lations between data of consecutive parities seem to be high, excepting those including
the first litter, which go from 0.7 with the second to 0 with the fourth (for NB and NA).
So it appears that data of first parity are a poor enough information about the genetic value
of sows ; on another hand, taking into account the genetic correlation between parities could
improve the efficiency of selection on litter size.
Crossbreeding of pigs : effects on growth, feed conversion and carcass
L. LAZAREVI&jadnr;, M. MILOJI&jadnr;, B. SIMOVI&jadnr; I. CAJIC
Faculty of Agriculture, 11081 Zemun, Yugoslavia
Heterosis and maternal effects on daily gain, feed conversion ratio and carcass traits
were investigated in the pig crossbreeding experiment. Three breeds of pigs were used :
Large White, Dutch Landrace, and Swedish Landrace. Nine genetically different pig groups
of purebreds and crossbreds had been examined. General heterosis effects were small and
nonsignificant. Comparisons between pure breeds show small differences with Dutch
Landrace to some extent exceeded two other breeds. Significant specific heterosis effects
were found for daily gain, feed conversion ratio and fat thickness at shoulder. Average
difference in reciprocal crosses or general maternal effects were significant for daily gain
and feed conversion. Specific maternal effects were significant for all characters studied,
with exception for carcass length.
Use of micro-computers in the field for estimating breeding values :
a system to automatically collect all data handled on a population
in a computer compatible way for further processing
E. GROENEVELD
Institut fiir Tierzucht und Tierverhalten Mariensee (FAL)
3057 Neustadt 1, Federal Republic of Germany
Definition and development of breeding programs require data as a basis of analysis.
A micro computer system is described which supports and carries out the routine calculations
that have to be done in a breeding program. All data handled are stored on floppy discs or
cassettes. Input is checked for plausibility. Data transmission to a central computer is via
a direct link between the micro computer and the host. As a by-product of index calculation
for auction boars in Northern Germany data on 23 000 boars have been collected in 1980,
which comprises the total male population on sale in this region and 40 p. 100 of all
boars sold in the Federal Republic of Germany.
What can be gained by the BLUP procedure under various circumstances ?
C. HAGGER L. DEMPFLE *
* Institut /iir Tierproduktion, ETH Ziirich, ETH-Zentrum, CH - 8092 Zurich
**Lehrstuhl fiir Tierzucht der TU-Miinchen, D-8050 Freising-Weihenstephan
In recent years the Blup procedure has replaced older procedures like the Contemporary
Comparison method and the Herdmate method. The two main differences between Blup
and the older methods are : all factors considered are estimated simultaneously and available


Heritability of litter size, phenotypic and genetic correlations between the four first litters of Large White sows

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Felgines C

Bolet G

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Heritability of litter size, phenotypic and genetic correlations between the four first litters of <it>Large White </it>sows

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C. FELGINES

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Heritability of litter size, phenotypic and genetic correlations between  the four first litters of Large White sows

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Heritability of litter size, phenotypic and genetic correlations between the four first litters of Large White sows

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