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Swine breeding and genetics in France

 

C. LEGAULT -

Institut National de la Recherche Agronomique

Centre de Recherches de Jouy - Station de Genetique quantitative et appliquee

78352 - JOUY en JOSAS Cedex - France

 

ABSTRACT

 

The pig population in France in 1991 numbered 12.1 million animals including 1.14 millions reproducing sows; it produced about 22 million carcasses (average weight of 85.7 kg) corresponding to 89 % of the national consumption in pig meat (38 kg per capita).

 

The distribution of sows according to (the) genetic type is as follows: crossbred Large White x Landrace (91 %), Large White (5 %), French Landrace (2 %) and Pietrain (1 %). The distribution of boars used in artificial insemination (35 ~k) on January 1st 1993 was: Large White 8 %, French Landrace 7 %, Pietrain 15 %, Pietrain x Large White 33 ~k, various composite and specialized terminal boars: 37 %. In natural mating the proportion of pure Pietrain boars is very low.

 

The breeding animals are owned by 3 kinds of partnerships in the following proportion: independant pig breeders (10 %), breeding cooperatives (55 %) and breeding companies (35 9b). The national breeding scheme deals with the first two. It is based on a combined performance and sib testing procedure in national testing stations (3000 boars/year) completed by an "on farm" performance testing program (70 000 animals/year). The selection objective combines daily gain, feed efficiency, lean percentage, dressing out percentage and meat quality. Moreover, comparisons of terminal products from differents schemes (cooperative and breeding companies) are regularly carried out.

 

A computerized field recording program permits the analysis of the components of the sows' numerical productivity (800 000 litter/year). On the basis of a selection index on litter size, it has also enabled the selection at a so-called "hyperprolific strain of boars" used in A.I. in the Large White breed.

 

Over the last 20 years, the average annual genetic progress in the Large White breed has been estimated at near 8 g/year for daily gain; .03 kg/year for feed efficiency ratio and .35 points for lean percentage. During the same period, a phenotypic yearly improvement of .3 pigs weaned/sow/year was observed in sows.

 

Estimation of breeding values by means of Blup-animal model methodology will be implemented in 1993 for production traits and in 1994 for reproduction traits. In the near furture, the priority will be given to the genetic improvement of daily gain, meat quality and litter size. Recently identified major genes (such as Halⁿ, Rn^-, Mu⁺...), associated with advances in biotechnologies (PigMap), will probaly present complementary garanties for success.

　

Swine breeding and genetics in France

 

C. LEGAULT

 

Institut National de la Recherche Agronomique

Centre de Recherches de Jouy

Station de gendtique quantitative et appliquee

78352 JOUY-en- JOSAS Cedex - France

 

I - INTRODUCTION

 

With 1.85 million tons produced in 1991, France is the 3rd largest pig meat producer in the European Community (after Germany and Spain). In 1992, France has almost achieved self sufficiency producing 89 % of its requirements (38 kg per capita). The pig population in 1991 numbered 12.1 million animals including 1.14 million saws producing about 22 millions carcasses averaging 85 kg.

 

Important structural changes in the structures have led to greater specialisation on pig farms. In 1991, there were 145.000 pig farmers compared to 523.000 in 1974. At present, 80 % of all pigs in France are in fact to be found in 10.000 herds of over 400 heads.

 

The majority of pig farmers breed and fatten their stock. Pig keeping is confined t( certain regions, (figure 1): In 1992, over 65 % of pigs produced in the country came from the "Bretagne" and "Pays de Loire" regions. Since 1970, great progress was observed due to the organization of production by the development of "Pig producers groups". Over 80 % of pig produced in 1992 come from these groups.

 

II - GENERAL CONSIDERATIONS ON PIG BREEDING IN FRANCE

 

The breeding animals are owned by 3 categories of partnerships in the following proportions:

- Independent pig breeders:        10 %

- Breeding cooperatives:     55 %

- Breeding companies:        35 %

 

Over 80 % of breeding animals are owned by less than 10 breeding cups (cooperatives or companies).

 

The national breeding program is defined and managed by the national committee for animal breeding (commission nationale d'amelioration genetique) created by the "animal breeding act" (1966). The national breeding scheme deals with the individual; and cooperative pig breeders directly. As will be described more in detail later, i) activity is based on national testing stations, completed by an "on farm performance testing" program and a computorized field recording program for reproductive sows. Moreover, comparisons of "terminal products" from different schemes (including breeding companies) are regularly carried out.

 

The use of artificial insemination has increased very quickly during the last few years (35 % in 1993 compared to 5 % in 1988). In selection herds, this percentage is about 40 %.

 

The distribution of sows according to the genetic type is as follows (figure 2a.) crossbred Large White x French Landrace: 91 %; Large White: 5 %; French Landrace: 2 %; Pietrain: 1 %. The distribution of boars used in artificial insemination was as follows on January 1st 1993; Large White: 8 %; French Landrace 7 %; Pietrain: 15 %; Pietrain x Large White: 33 %; various composite and specialized terminal boars: 37 % (figure 2.b.). In natural mating, the proportion of pure Pietrain boars is very low.

 

Other breeds, including Duroc, Chinese breeds, Creole, Corsican pig and native breeds (Gascon, Limousin, Basque, Normand) represent well under 1 % of breeding animals.

 

In summary, (figure 3): the pig industry is dominated by crossbreeding schemes (over 95 % of slaughtered pigs) with a great homogeneity in the dam lines (F1 Large White x Landrace), and a relative heterogenity in terminal sire lines; the overall distribution of terminal boars (used in natural and artificial matings) is as follows: pure breeds (essentially Pietrain): 12 %; Crossbred F1: {Pietrain x Large White; Pietrain x Duroc etc...): 46 %; and composite specialized terminal boars: 42 %. The proportion of this last category of boar is increasing.

 

III - GENETIC IMPROVEMENT OF PRODUCTION TRAITS: GROWTH,

CARCASS AND MEAT QUALITY

 

The national breeding scheme is based on a combined performance and sib testing procedure in 4 national testing stations (3000 boars/year) completed by an "on farm" performance testing program (75 000 animals/year). It is also completed by the on farm "Technico-economical program (G.T.E.) managed by the "Institut technique du Porc" (DAGORN et al., 1992). The selection objective combines daily gain, feed efficiency, lean percentage, dressing out percentage and meat quality. Moreover, comparisons of terminal products from differents schemes (cooperative and breeding companies) are regularly carried out.

 

1. The national testing stations

 

A combined performance and sib testing procedure has been used in the 4 national testing stations since 1987. The purpose of this type of recording is to maintain meat quality at a constant level. The principle is to link the performance of the potential breeding pig with that of a full brother or sister (sib) which is slaughtered and cut up to obtain information on body composition and meat quality. The performance figures of both animals (the candidate to selection and its sib) are then combined within a selection index including a constraint on meat quality. A theoretical study shows that without 'constraint on meat quality, both methods (performance testing and combined testing) lead to a significant deterioration of meat quality due to unfavourable genetic correlations between meat quality and other selected characters (daily gain and lean percentage). When meat quality is constrained, the overall efficiency of the combined selection index is satisfactory (+15 % compared to the reference situation). This is why it has been decided to gradually replace individual testing by combined testing of boars in France. The best selected boars are reserved in priority for the artificial insemination centers.

 

The individual performance of young boars registered in 1991 is reported in Table 1 and the slaughter performance (growth, carcass and meat quality) of their collaterals compared to those of the terminal products of different breeding schemes is reported in Table 2.

 

2. On farm pig recording program

 

The combined performance and sib testing procedure in the national testing stations is completed by an "on farm" performance testing program. As shown in Table 3, this programs which dealt with over 75000 young boars and gilts in 1991, concerns mainly purebred animals (Large White, Landrace and Pietrain) and also Pietrain x Large White young boars selected for use as terminal boars. This program is managed by the "Institut Technique du porc" (ITP), the young breeding animals being classified within "control batch" on the base of a selection index combining 2 characters: the age at 100 kg and the backfat thickness at 100 kg.

 

3. Elimination of the sensitivity to halothane gene

 

The improvement of meat quality is considered a priority in by the French pig industry. The elimination of the sensitivity to halothane recessive gene responsible for P.S.E. also meat has the advantage of reducing financial losses due to the stress syndrome with a resultant mortality during the fattening period or transportations. In order to reduce as far as possible the proportion of halothane sensitive fattening pigs in commercial units, a decision was made in 1981 to eliminate the stress syndrome from the French Landrace breed. Since Large White in France are almost free from this unfavourable gene, it would be the same for the Fl Large White x Landrace crossbred parental sows. Under these conditions, terminal products would be normal in heterozygous or respect to stress sensitivity.

 

Under this scheme all young French Landrace boars recorded in national performance recording stations since 1981 have been submitted to the Halothane test. The effectiveness of this breeding scheme was increased in 1985 by the use of blood markers to enable pigs to be presumed carrying only one sensitivity gene, i.e. the heterozygotes, to be identified among animals not sensitive to, halothane (COUROT et al., 1989).

 

Blood markers used in France are phosphohexose isomerase (PHI) and 6 - phosphogluconate dehydrogenase (PGD), the electrophoretic variations of which at or near the loci are closely associated with the sensitivity to halothane locus. The French Landrace has now joined the Large White in respect of meat. quality characteristics recorded in national stations, thus putting an end to a long series of results which gave the Large White the reputation of produccing the highest quality meat {SAUGERE et al., 1989). Commercial farmers, butchers and meat processors now find that at most only 1-2% of fattening pigs are sensitive to halothane as a result of this knowledge.

 

New advances are represented by the use of molecular typing (FUJII et al., 1991; DALLENS and RUNAVOT, 1992) to detect the heterozygous animals as well in maternal breeds (Large White, Landrace ...) and in specialized sire lines.

 

4. The realised genetic progress for production traits

 

Several estimates of the genetic progress achieved through the national breeding program have been carried out (TIXIER and SELLIER 1986; OLLIVIER et al., 1991; DUCOS et al., 1993). Hence, over the last 20 years, the average annual genetic progress in the Large White breed has been estimated at near 8 g/year for daily gain; .03 kg/year for feed eKciency ratio and .35 points for lean percentage. Meat quality is the only trait for which a slight but regular decrease was observed. These genetic variations are illustrated for the Large White and French Landrace breeds by the Figure 4 (DUCOS et al., 1993). An other example of this change under field conditions for different measures of feed conversion ration is illustrated by figure 5 (DAGORN et al., 1992).

 

5. Two major genes influencing production traits

 

Recent advances in French pig research have lead to the identi6cation of two major genes influencing meat quality (Rn^- ) and backfat thickness (MU⁺) respectively.

 

The hypothesis of NAVEAU (1986) concerning the low pH (acid meat) and low technological yield was confirmed by research workers utilising a segregation analysis method (LE ROY et al., 1990). The effect of this gene is particularly important since the difference between homozygotes represents about 3 standard deviations in technological yield; its frequency was probably relatively high in the Hampshire breed ("Hampshire effect"). An experiment is being developed to specifically study this gene. Pig breeders have also decided to eliminate this gene.

 

Another dominant gene influencing backfat thickness was identified by LE ROY et al. (1990). The difference between homozygotes corresponds to 2 phenotypic standard deviation in backfat thickness. A more precise genetic study of this gene has also been decided.

 

Ⅳ. THE IMPROVEMENT OF REPRODUC PERFORMANCE

 

Litter size is considered to be the most important component of the sows' numerical productivity defined as the number of pigs weaned/sow/year (Pn) parameter which determines the cost of the piglet at weaning. However, litter size is particularly difficult to improve through usual selection methods because of its low heritability and its low repeatability. In this review, we will point out specific aspects of the French strategy regarding the improvement of sow productivity:

 

- A large scale computorized program.

- The selection of "hyperprolific strains of boars.

- The creation of Chinese-European composite maternal lines.

 

1. The computorized field recording of sow performance

 

The objective of the "National Sow Herd Management Programme" (GTTT), which was instituted in 1969, is to improve the numerical productivity of herds. This objective can be achieved by taking into consideration the various criteria recorded which make up overall productivity. This program is used by nearly 6.000 farmers (selectioners, multiplyers and producers). The figures represent a national data bank available for breeding and various comparisons.

 

These data are used as the basis for selecting sows according to prolificacy and regularity of breeding. Annual records, calculated for a twelve month period, contain the events which occurred in the herd during the last twelve months and in a reference group.

 

The main results are listed in Table 4 for pure breeds in 1991. The overall results observed in 1992 are listed in Table 5. This sample of nearly 900.000 litters represents 37 % of all litters born in France in 1992.

 

As will be developed later, this program is used to derive the sow prolificacy indexes. This enables hyperprolific sows to be identified to assist the national programme of creating hyperprolific lines. It also enables hypoprolific boars to be identified; these may be carrying chromosome anomalies.

 

The variations from 1970 to 1992 of the main reproductive performances of sows are represented on figure 6a for litter size (total born, born alive and weaned/litter), on figure 5b for lactation length and weaning-fertilization interval and on figure 6c two estimates of the numerical productivity. Over the last 20 years, an average phenotypic yearly improvement of .3 piglet weaned/sow/year has been observed.

2. The "Hyperprolific" strains of boars

 

French saws already have the reputation of being among the most productive in Europe (22.6 piglets weaned per sow per year in 1992. This figure is explained by:

 

– The high level of prolificacy: an average of 11.5 total piglets born and 9.4 piglets weaned per litter;

– intensive breeding – an average of 2.37 litters per sow per year, the result of an average farrowing interval of 153.6 days.

 

However, this productivity from sow herds should improve by 5-10 % in the next twenty years as a result of the development of a new method of selection, the hyperprolific method. The principle for the creation of a hyperprolific line which was explained for the first time in 1976 by LEGAULT and GRUAND is based on two key factors:

 

- Screening of sows with exceptionnal prolificacy (selection rate ranging from .2 to .5 %).

- The practice of successive back-crossing on this nucleus of exceptional sows which enables boars to be bred with a genetic value for prolificacy which tends to be asymptotically similar to that of their dams, after 3 or 4 generations (Figure 7). This principle has been applied by INRA to the Large White breed in order to create an experimental hyperprolific line of boars used in A.I.. The theory of the use of this line was tested in two evaluation trials in which the reproductive performance of the daughters of boars of the hyper line was compared with that of contemporary sows sired by control boars. In the first evaluation trial by LE ROY et al., 1987, daughters of hyper boars showed an advantage over their contemporaries of + 0.99 and + 0.88 piglets born and piglets born alive, respectively. More recently, a second trial confirmed the above results with advantages of + 0.73 and + 0.60 piglets born and piglets born alive per litter respectively.

 

The results presented above show that it is possible to obtain genetic progress conforming to theoretical forecasts on an as low a heritable trait as litter size, under three conditions:

 

- Using a computerized selection method for extreme animals within a very large population.

- Resorting to artificial insemination.

- Showing a collective spirit enabling the pooling of genetic potential of the greatest number of breeding stock possible.

 

However, this simple method, relying for effectiveness on an extremely rigorous selection rate (less than 1 %) and the distribution capacity of A.I., should improve tremendously very shortly: using the BLUP – an animal model which takes account of the information available on all collaterals will bring a considerable improvement to accuracy in screening exceptional animals. In addition, the situation is confirmed by the expansion of A.I. which multiplies the "genetic connections" between herds.

 

During these last few years, French professionals have become more and more interested in developing and using hyperprolific lines in the Large White and French Landrace grandparent female breeds. It was to regularise this situation that the Ministry of Agriculture draped rules with the consent of INRA and ITP. According to these rules, a Large White boar is granted hyperprolific status when its prolificacy index exceeds or is equal to 110 (threshold corresponding to 2.5 standard deviations above the average for the breed). In the Landrace, this threshold is 108 (2 standard deviations). At the beginning of 1993, 25 Large White boars and 6 Landrace boars meeting this quali6cation were in service in French artificial insemination centres.

 

3. Reciprocal translocations in the pig: detection, eradication and prevention

 

Reciprocal translocations are the most studied structural chromosomic abnormalities in the pig due to their desastrous effects on reproduction. Indeed, the size of the litters produced by breeding animals bearing such an abnormality is reduced by 40 % to 50 % due to embryonic mortality at implantation. As a consequence, the yearly economic loss of a translocated boar ranges from 30.000 FF to 50. 000 FF in natural mating and 10 to 15 times more in artificial insemination (Al). Thirty of the 50 or so translocations presently described in the pig were discovered in two countries, Sweden and France, POPESCU (1990). Fortunately, the frequency of translocations is relatively low (about 1/1500).

 

Any breeding animal producing small litters may be suspected to carry a translocation with a probability depending on the quality and the precision of the available information. The principle and efficiency of the detection of reciprocal translocations through a computerized field screening system are discribed (LEGAULT and POPESCV, 1993). In France, such a screening program enabled the detection of about 40 "hypoprolific boars" per year, 40 % of which carried a translocation, as subsequently revealed by caryotype analyses.

 

A screening system which includes all hereditary abnormalities and based on the examination of the 20 first litters produced by AI boars is proposed. This method should involve the material and financial participation of AI centers.

 

4. Chinese crossbred animals: a new opportunity

 

On the basis of an estimation of Dickerson's crossbreeding parameters between Meishan and Large White breeds, LEGAULT and BIDANEL (1992) discusses several strategies for taking advantage of prolific Chinese breeds as maternal components in crossbreeding schemes under different production systems. In fact, Chinese breeds could play an active part in the improvement of the efficiency of the pig industry as suggested by recent development of research and breeding projects in an increasing number of ceuntries. Among different possible strategies for taking advantage of prolific Chinese breeds in various market conditions, the creation of composite lines selected in favour of growth and body composition seems to be by far the most promising.

 

A first illustration of this theoretical expectations is given by the results of 8 generations of selection for lean growth rate in a sino - european composite line (NAVEAU et al., 1992; Figure 8): lean content has been improved by almost 10 points %; litter size decreased between generations 1 and 2 (due to the loss of half of the maternal heterosis effect) but remain rather constant from generations 2 to 7. (The composite line exhibits a superiority of 2.6 pig weaned per litter over the european foundation breed).

 

V - PROSPECTIVE ASPECTS

 

The general objective of research carried out by the pig unit of the INRA Quantitative and Applied Genetics Station (SGQA) at Jouy - en - Josas is the study of hereditary transmission and methods of genetic improvement of quantitative characteristics with an economic nature in the pig meat production. This involves the development of optimum breeding programmes, the testing of new selection criteria and the evaluation of different genetic material (pure breeds and crossbreds). The work is based on information collected on farms or from National Breeding Stations and from experiments conducted on INRA herds. Other laboratories of the IKRA Department of Animal Genetics are also involved in pig research, principally in the field of chromosome abnomalities, genetic map, immunogenetics (SLA major histocompatibility complex) and molecular biology.

 

Producing quality pigs at the lowest possible cost will remain the main goal of pig breeders in the near future. However, some changes in the priorities due to the decrease of the price of cereals on the world market and due to the french grading system of carcasses (figure 9). Thus, the priority will be given to the genetic improvement of daily gain, meat quality and litter size. Estimation of breeding values by means of Blup-animal model methodology will be implemented in 1993 for production traits and in 1994 for reproduction traits. Recently identified major genes (such as Hal, Rn^-, Mu⁺ ...), associated with advances in biotechnologies (PigMap), will probably present complementary guarantees for success.

 

Concerning reproduction, it seems obvious that pig breeding professionals will no longer be content in the future with grandparent female lines which, in terms of reproduction, are of constant level. It has been be shown that the Large White is likely to progress fairly rapidly for prolificacy and that this progress can be added to the effect of heterosis in crossbreeding. If, for the moment, the limiting factor remains the Large White sows' ability to rear large litters up to weaning, there are nevertheless great hopes with the forthcoming arrival on the market of composite Sino-European lines, which are expected to partner the prolific Large White lines at grandparent female level.

 

REFERENCES BIBLIOGRAPHIQUES

 

COURREAU J.F., SELLIER P., BOULARD J., BRETON T., GOULLIEUX P., GUERIN G., 1985. Marqueurs sanguins (Phi et Pgd) et sensiblitb h l'halothane chez le porc Landrace Franglais. Journdes Rech. Porcine en France, 17, 95-104.

 

DAGORN J., BADOUARD B., LEGAULT C., 1992. Performance control of pig farms in France. From technical support to national data banks. Satellite Symposium on: Pig management information systems, Madrid, Espagne, 12 september 1992, 1-10, European Association for Animal Production, Commission in Pig Production.

 

DALENS M., RUNAVOT J.P., 1993. Test moleculaire pour le d4pistage du one de la sensibilite a l'halothane chez le porc. Techniporc. 1993-1, 17-21.

 

DUCOS A., BIDANEL J.P., BOICHARD D., DUCROCQ V., 1993. Nouvelle estimation des parametres genetiques pour les caractkres de croissance, carcasse et qualite de la viande dans les races Large White et Landrace Franglais. 1. Caract0res mesures dans les stations publiques. (New estimation of genetic parameters for growth, carcass and meat quality traits for the Large White and French Landrace pig breeds. 1. Traits recorded in central stations.) 256mes Journdes de la Recherche porcine en France, Paris, 2-4 fevrier 1993, 43-50, ITP, Paris.

 

FUJII J., OTSU K., ZORZATO F., DE LEON S., KHANNA V.K, WEILER J., O'BRIEN P.J., MACLENNAN D.H., 1991. Identificaiton of a mutation in porcine ryanodine receptor associated with malignant hyperthermia. Science, 253: 448-451.

 

LE ROY Pascale, LEGAULT C., GRUAND J., OLLIVIER L., 1987. Heritabilite realisee pour la taille de portee dans la selection de truies dites "hyperprolifiques". (Realized heritability for litter size in selection of "hyperprolific" sows.) Genet. Sel. Evol., 19, 351-364.

 

LE ROY P., ELSEN J.M., NAVEAU J., 1990. Etude de la variabilite genetique de 1'adiposite dans la lignee Laconic. (Study on genetic variability of fatness in the Laconic line.) 22emes Journees de la Recherche porcine en France, Paris, 30-31 janvier et ler fevrier 1990, 11-16, ITP, Paris. (Ann. Zootech., 39, 139-140, res. + abstr.)

 

LE ROY P., NAVEAU J., ELSEN J.M., SELLIER P., 1990. Evidence for a new major gene influencing meat quality in pigs. (Mise en evidence d'un nouveau gene majeur influant sur la qualite de la viande de porc.) Genet. Res., 55, 33-40.

 

LEGAULT C., GRUAND J., 1976. Amelioration de la prolificite des truies par la creation d'ye lignite "hyperproli6que" et 1'usage de 1'insdmination artificielle: principe et r6sultats expdrimentaux prdliminaires. Journees de la Recherche porcine en France, Paris, fevrier 1976, 201-206. (Ann. Zootech., 25, 445, res. angl.).

 

LZGAULT C., BIDANEL J.P., 1992. Overall review of genetical research on Chinese pigs in France and prospects for exploiting Chinese crossbred animals. (Revue d'ensemble des recherches en g4nbtique sur les pores chinois en France.) Proceedings of the International Symposium on Chinese pig breeds, Chen Runsheng (Ed.), Harbin, China, August 11-14, 1992, 10-23, Northeast Forestry University Press, Harbin, China.

 

LEGAULT C., POPESCU C.P., 1993. Les translocations r6ciproques chez le porc domestique: detection, eradication et prevention. (Reciprocal translocations in the pig: detection, eradicatian and prevention.) Elevage et Insemination, nº 254, 1-12.

 

NAVEAU J., 1986. Contribution 5 1'6tude du ddterminisme gdn4tique de la quality de viande porcine. Hdritabilit4 du Rendement Technologique Napole. In 18hme Journ4es de la Recherche Porcine en France, pp.265-276. Paris: Institut Technique du Porc.

 

NAVEAU J., DUCOS A., BIDANEL J.P., BAZIN C., 1992. Results on eight generations of selection for lean growth rate in the Sino-European Tiameslan composite line. Proceedings of the International Symposium on Chinese pig breeds, Chen Runsheng (Ed.); Harbin, China, August 11-14, 1992, 632-637, Northeast Forestry University Press, Harbin, China.

 

OLLMER L., LAGANT H., GRUAND J., MOLENAT M., 1991. Progres g0ndtique des pores Large White et Landrace franglais de 1977 a 1987. (Genetic progress in French Large White and Landrace pigs from 1977 to 1987.) 23emes Journdes de la Recherche porcine en France, Paris, 389-394, ITP, Paris. (Ann. Zootech., 40, 348-349 (res. abstr.))

 

POPESCU C.P., 1989. Cytogenetique des mammiferes d’elevage. (Cytogenetics of farm animals.) Institut National de la Recherche Agronomique, Paris, 114 pages.

 

SAUGERE D., RUNAVOT J.P., SELLIER P., 1989. Un premier bilan du programme de selection contre le gene de sensibilite a 1'halothane chez le porc Landrace Franc,ais. (First results of the breeding programme implemented for decreasing the frequency of the halothane sensitivity gene in the French Landrace breed.) 21emes Journees de la Recherche porcine en France, Paris, 31 janvier, 1 et 2 fdvrier 1989, 335-344, ITP, Paris. (Ann. Zootech., 38, 201, abstr.)

 

TIXIER Michele, SELLIER P., 1985. Evolutions genetiques des performances de croissance et de carcasse dans les races porcines Large White, Landrace francais et Landrace beige. (Genetic trends for growth and carcass traits in the Large White, French Landrace and Belgian Landrace pig breeds.) 17emes Journees de la Recherche porcine en France, Paris, 30-31 janvier et ler fevrier 1985, 75-86, ITP, Paris. (Ann. Zootech., 34, 362-363, abstr.) (Techni- Porc, 8 (6), 59-60, res. fr.)

　

Table 1: Performance of young boars collected in the French national testing stations in 1991.

Character	Large White	French Landrace	Belgium Landrace	Pietrain
Number of boars	1781	876	45	422
Age at 35 kg (d)	82.2	82.6	99.1	90.2
Age at 90 kg (d)	142.0	144.3	167.7	161.1
Av. daily gain (g)	928	898	789	764
Feed efficiency ratio (kg)	2.365	2.463	2.580	2.477
Back fat thickness (mm)	10.8	11.2	10.2	7.6

　

　

Table 2: Slaughtered performance collected in French national testing stations in 1991

	Large White	French Landrace	Pietrain	Terminals
Number of pigs	967	535	138	479
Average daily gain (g)	911	877	761	859
Feed efficiency ratio (kg)	2.81	3.01	-	2.79
Age at slaughter(day)	155	156	169	159
Weight at slaughter(kg)	100.8	100.0	95.0	101.0
Dressing out (%)	79.2	78.2	81.5	79.7
Estimated lean (%)	52.8	51.0	63.1	55.1
Subjective meat quality score	11.0	11.6	4.0	9.9
Water holding capacity	9.7	9.9	3.4	8.3
Reflectance	586	569	670	589
pH 24h. (Adductor femoris)	5.88	5.96	578	5.83
Meat quality index	10.8	11.5	8.5	10.2

 

Table 3: Results of the "on farm" national performance testing program in 1991.

Breed	Sex	Number of animals	Number of testing groups	Weight at control (kg)	Age at 100 kg	Backfat thickness at 100 kg
Large White	M	13465	410	100	146	11.6
	F	28813	652	96	154	12.8
French Landrace	M	7549	251	98	151	12.4
	F	14571	336	93	158	13.3
Pietrain	M	2457	51	96	171	6.7
	F	2105	57	92	172	7.5
Pietrain x LW	M	10874	365	100	158	9.6

M: Males; F: Females

　

Table 4: Reproductive performance of pure bred sows in French in 1991

Criteria		Large White	French Landrace	Belgium Landrace	Pietrain
Number of Litters		12.306	5306	286	938
Number of Farms		78	36	5	10
Farrowing interval (days)		154.9	156.3	170.2	162.8
Lactation duration (days)		28.7	28.1	34.2	33.7
Weaning-fertilization interval (days)		11.1	12.9	20.0	13.2
Litter size	Born alive	10.4	10.1	9.1	9.8
	Still born	0.8	0.7	0.5	0.9
	Weaned	8.9	8.7	8.0	8.0
Age at first farrowing		358	351	379	374
Number pig weaned/ sow/ year		21.0	20.8	17.2	17.9

 

Table 5: Reproductive performance of French sows in 1992: (90 % of these sows are crossbred Large White x French Landrace).

Number of litters: 893.602 Number of farms: 6.777		Mean Value	Between-farm standard deviation SF
Number of pigs weaned / sow / year (reproductive life)		22.4	2.3
Number of pigs weaned / sow / year (from 200 days of age to the last weaning)		21.6	1.9
Liter size	born alive	10.8	0.8
	still born	0.7	0.4
	weaning	9.4	0.8
Mortality rate (weaned/total born)		17.8%	5.7
Lactation duration (days)		27.3	2.7
Farrowing interval (days)		153.6	12.0
Weaning-fertilization interval (days)		11.2	11.6
Number of litters weaned at culling		4.6	1.4

       

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