Parameters of meat quality and stress resistance of pigsParamètres de la qualité de la viande et la résistance au stress chez le procParameter der Fleischbeschaffenbeit und der Stressresistenz beim Schwein

Selection criteria for the improvement of meat quality and stress resistance of the Swiss pig breeds are given. The parameters of meat quality and stress resistance were estimated on 2680 Large White and 1567 Landrace pigs from the Swiss Performance Testing Station. The results indicate the possibility of improving meat quality by selection. Estimations made on the warm carcass (pH1) and on the cold carcass (reflectance) are suitable in combination for characterising meat quality. The heritabilities of meat quality (pH1, reflectance) vary between 0.14 and 0.27. For Landrace, in contrast to Large White pigs, the creatine-kinase test (CK test) and the halothane test allow conclusions to be drawn in the live animal on stress resistance and meat quality post mortem. The heritability of the CK value in Landrace pigs is 0.73 ± 0.18, and in Large White pigs 0.37 ± 0.11.Our results led to the following organisation of selection on meat quality and stress resistance in Switzerland. Testing at the station (mainly full sib tests) includes meat quality measurements. Boar performance tests include the halothane and CK tests. In the field, the Swiss Performance Testing Station offers the halothane test as a service to breeders of nucleus Landrace herds. Preparations are being made to apply the CK test in the field.     

The pH1 of longissimus dorsi muscle in purebred and commercial pigs

The pH was measured at 45 min post-mortem (pH₁) in the longissimus dorsi muscle (lumbar region) of 8 188 pigs as a criterion of meat quality. The results showed that purebred animals had a lower average pH₁ (6.53 ± 0.01) than commercial (6.59 ± 0.01) and that the Irish Landrace breed had a lower average (6.48 ± 0.01) than the Large White (6.64 ± 0.01). The proportion of pH₁ values < 6.0 was greater in Irish Landrace than in Large White pigs. The incidence of pH₁ < 6.0 was 5% for all pigs and 11% for purebred Landrace. Females had a greater number of pH₁ values < 6.0 than had male castrates.     

Testing methods for PSE syndrome: Current research in DenmarkMéthodes de testage sur le syndrome PSE: Recherches en cours au DanemarkMethoden zur Feststellung des PSE-Syndroms: Aktuelle Forschung in Dänemark

The purpose of the paper is to describe research carried out in Denmark in areas associated with PSE.In the carcass, meat colour is used as an expression of meat quality. Meat quality deteriorated until 1972 but has improved substantially during the last 6–7 years.The incidence of halothane susceptibility in the Danish Landrace breed is low. Approximately 60% of the halothane-susceptible pigs had PSE carcasses compared to 22% for the non-susceptible pigs. However, pigs heterozygous at the Hal locus are intermediate in meat quality, and elimination of the gene for halothane susceptibility will lead to a substantial improvement in meat quality. A proportion of halothane-susceptible pigs as well as heterozygous carriers can be detected indirectly by using the H blood group system alone or in combination with the PHI system. This is due to linkage disequilibrium between the three systems within the Danish Landrace breed. Use of the H and PHI systems and the halothane test in combination with full sib information on KK index may increase the genetic gain by 5–30%. However, a greater extra gain is easily obtained by a slight increase in selection intensity based on the KK index alone. Thus, it does not seem profitable to use blood and enzyme types or halothane test as a routine in selection against PSE under Danish conditions. In contrast, these tests are useful within herds with a high frequency of PSE.     

Effect of environmental design on the growth and behaviour of weaned pigsInfluence de milieux expérimentaux sur la croissance et le comportement des porcs sevrésEffect der umweltgestaltung auf das wachstum und verhalten abgesetzter ferkel

Large White × Landrace pigs weaned at 24–29 days were placed in a structured environment planned as a 2 × 2 factoral design. The two variables were the presence or absence of a box (1.2 m × 0.92 m × 0.86 m) and the presence or absence of an extended floor which increased the solid area in the control pen from 60% of the total area to 80%. The box with no extended floor exceeded all other environments in stimulating the relative growth rates of the piglets. On removal of the temperature covariance the box still accounted for most of the variance in relative growth rate. Elements of the box (element 1, corner, back and side wall; element 2, corner, front and side wall; element 3, side wall only; element 4, back wall only) were tested for effect on relative growth rate and it was found that element 3, side wall only, promoted the most regular growth rates. The rates of agonistic behaviour over each 10 min were not significantly different for pigs in any of the tested environments.     

Changes in the phenotype for halothane sensitivity in pigsChangement du phénotype de sensibilité, à l'halothane chez le porcPhänotypische veränderungen in der empfindlichkeit auf halothan bei schweinen

One hundred-and-one hybrids of the Canadian Landrace, Large White, Belgian Landrace and Duroc breeds were repeatedly tested for sensitivity to halothane at the age of 8–15 weeks. Changes in the number of reactors were recorded in the experiment. The number of reactors was 40 in the first test, 33 in the second and 30 in the third. Two individuals changed from non-reactors to reactors; 12 reactors assessed by the standard halothane test ceased to differ during repeated tests from non-reactors. However, these individuals with secondary non-reactivity transmitted halothane-sensitivity to the progeny.     

The heritability of pH1 in longissimus dorsi muscle in landrace and large white pigs

The susceptibility of a carcass to PSE (pale, soft, exudative muscle) can be assessed by measuring the pH value in the lumbar region of the longissimus dorsi muscle at 45 min post-mortem (pH₁). The effect of breed, station, sex and season on pH₁ was investigated, on a total of 2 775 pig records, including the progeny of 129 Irish Landrace and 126 Large White boars, from two test stations. The heritability of pH₁ and its genetic correlation with other performance characteristics were determined within each breed. Landrace pigs had significantly lower values than Large White pigs, indicating a greater susceptibility to PSE in the former. There was no significant difference between the values for boars, castrates and females. There were marked differences from month to month, but no definite seasonal pattern was present nor was there any apparent long-term trend. The heritability for the Landrace breed was higher than that for the Large White breed, and both values indicate that pH₁ would respond to selection. The genetic correlations between pH₁ and daily gain, food conversion efficiency and backfat (four measurements) were for the most part low and the standard errors relatively high, indicating that there was no strong relationships between pH₁ and these performance characteristics.     

Energetic aspects of feed conversion in growing pigsL'indice de consommation chez le pore en croissanceEnergetische aspekte der futterverwertung beim wachsenden schwein

Feed conversion ratio (FCR), which defines the feed requirement in kg per kg body weight gain, is an important measure for judging the economic and breeding performance of a fattening pig. It is dependent on many different factors which include (1) the level of feeding, which affects the maintenance requirements, (2) the energy value of the ration and (3) the energy concentration of the body weight gains (c_g). The influence of these factors on FCR and, in general, on growth performance, is discussed using results from growth and balance experiments. Some inter-relationships between the factors are described and integrated into a model which predicts FCR.An increase in the level of feeding can reduce FCR. Experimental results indicate that the ad libitum fed pig has a lower maintenance requirement than the restrictively fed animal due to a reduction in its physical activity. As the level of feeding increases, there is usually a rise in c_g and an accompanying decline in FCR. However, FCR is only a useful indicator for judging the energetic efficiency of growth when c_g is known. A small FCR is only found when body weight gains are high and c_g low.     

The net energy value of balanced diets for growing pigsValeur enérgétique nette des rations équilibrées pour les porcs en croissanceDer nettoenergiegehalt von ausgewogenen rationen für wachsende schweine

Experiments with 80 growing pigs of Danish Landrace were performed to study factors influencing the net energy value of balanced diets and to develop an energetic feed evaluation system for pigs.Although balanced with regard to essential nutrients, the cereal based diets varied widely in chemical composition and accounted for 90% of the variation in the chemical composition of the diets used in practice. The pigs were distributed on dietary treatments on a within-litter basis taking sex and weight into account. The experimental period lasted from 20–90 kg live weight. The daily intake of the different diets was regulated in such a way that the daily gain in the different treatments was almost identical through the entire experimental period.Six digestibility and balance experiments were performed with each pig; at approximately 90 kg live weight the pigs were killed, dissected, ground, mixed and then chemically analysed. The diet composition had a highly significant influence on digestibility, metabolizability and efficiency of utilization of metabolizable energy. Energy concentration (ME/kg DM) accounted for 90% of the variation in the net energy value of metabolizable energy. This result was adopted as a basis for the official energy evaluation in Denmark in 1976, and the net energy content of diets and feedstuffs is calculated from the equation Net energy ($\text{MJ}\text{kg DM}\text{) = ?1.88 + 0.75 ×}\text{ME}\text{(}\text{MJ}\text{kg DM}\text{)}$The net energy value of 1 kg common barley, i.e., 7.72 MJ is defined as a feed unit for pigs. The investigations are continued to elucidate, in greater detail, the influence of the individual nutrients, sites of absorption, etc.     

Selected problems of B vitamins in animal nutritionQuelques problemes sur les apports alimentaires de vitamines BAusgewählte Probleme der B-Vitamine in der Tierernährung

Studies on vitamin B₆ and pantothenic acid conducted with pigs, poultry and veal calves are presented to demonstrate the difficulties involved in research on B vitamins. The analysis of the B vitamins already poses problems, so that recommendations on dietary requirement must be seen in the light of the respective analytical procedures used. A distinction must be made between the minimum and optimum requirements of the animals. Today, the dietary provision of the optimum requirements is of priority and needs suitable and sensitive biochemical criteria or performance criteria for assessment.Studies using early-weaned and market pigs demonstrate that, in the case of vitamin B₆, the urinary xanthurenic acid secretion after a tryptophan load and the activities of the serum transaminases are suitable biochemical criteria to diagnose suboptimum supply. Though these criteria were less responsive in poultry than in pigs, nevertheless, when the supply of vitamin B₆ was suboptimal in broiler chicken, the body's retention of dry matter, nitrogen and energy, providing measures of true performance, proved to be affected adversely.The assessment of the optimum vitamin B requirement for practical feeding rations is illustrated with results from studies on the pantothenic acid requirement of broilers and market pigs. On the basis of live weight gain and feed efficiency, and also taking into consideration biochemical criteria provided by pantothenic acid and coenzyme A levels in the blood and liver, an optimum pantothenic acid requirement of 8 mg per kg of feed is recommended for broilers and 9 mg per kg of feed for market pigs. The dietary requirement of piglets, market pigs and broilers for vitamin B₆ is estimated to be 3 mg per kg of feed.     

Lactation curves of friesian-bunaji crosses in NigeriaCourves de lactation de croisées frisonne-bunaji au NigeriaLaktationskurven von friesian-bunaji rinderkreuzungen in Nigeria

The validity of the gamma function to describe lactation curves of $\text{1}\text{2}$ and $\text{3}\text{4}$ bred Friesian-Bunaji crosses was investigated. The function explained 71% of the variation in yield in lactations which differed in duration, parity and season of calving. The effect of these variables on the components of the lactation curve was analysed by least-squares procedures. The goodness of fit of the function did not differ between classes of varying duration of lactation; short lactations, however, in addition to a lower persistence, also showed a low level of production. Lactation curves of first parity were flatter and also had a greatly reduced level of production compared to higher parities.Multiplying factors for estimating total lactation yield from part records were obtained from the fitted curves. The accuracy of prediction was greater when separate factors were used for each class of lactation length. The usefulness of part records in progeny testing is also discussed.     

The net energy value of crude fat for growth in pigsValeur énergt́ique nette des matières grasses pour la croissance du porcDer Nettoenergiewert von Rohfett für das Wachstum bei Schweinen

An experiment with 36 growing pigs of Danish Landrace was performed to study the influence of crude (animal) fat on the digestibility of crude fat and on the efficiency of utilization of metabolizable energy.The pigs (females from 3 litters and male castrates from 3 litters) were distributed on six dietary treatments on a within-litter basis, taking into account the live weight of the pigs. The daily intake of the different diets was regulated in such a way that the daily gain in the different treatment groups was almost identical throughout the entire experimental period from 20–90 kg.Three digestibility and balance experiments were performed with each pig, and at approximately 90 kg live weight the pigs were killed, dissected, ground, mixed and chemically analysed. The digestibility of crude fat increased with increasing concentration of dietary fat and the efficiency of utilization of metabolizable energy was increased by 5.0 kJ g^?1 digestible crude fat.Digestibility experiments with ileo-caecal cannulated pigs showed that the proportion of the digested crude fat and fatty acids disappearing in the caecum—colon decreased with increasing concentration of dietary crude fat, which results in a positive contribution of digestible crude fat to net energy besides its contribution to metabolizable energy.     

Heritability of clinical tail-biting and its relation to performance traits

Clinical tail-biters were identified over a 12-month period at a commercial nucleus pig-breeding farm that had a history of tail-biting problems. The breed, gender, and relative size of the tail-biters were recorded. Using pedigree data for all the pigs on the farm at the time of observations, the heritability of the tail-biting behaviour was estimated for purebred Large White (LW) and Landrace (LR) pigs. The incidence of tail-biting was 2.8% for Large White and 3.5% for Landrace (breed effects, P<0.10). Tail-biting was found to be heritable in Landrace (h²=0.05±0.02, P<0.05 as a 0-1 trait, equivalent to h²=0.27 as a continuous trait), but not heritable in Large White pigs (h²=0.00±0.00, as a 0-1 trait). In the Landrace population, tail-biting was unfavourably genetically correlated with leanness [lean tissue growth rate (LTGR; r_g=0.27, P<0.05), and back fat (BF) thickness at 90 kg (r_g=−0.28, P<0.05)]. It is concluded that past selection for desirable production traits may have resulted in increased predisposition to exhibit tail-biting behaviour. From the correlations and covariance matrix reported, it would be possible to develop a selection index to reduce the predisposition to exhibit tail-biting behaviour through selective breeding.     

The metabolic body size of the growing pigLe niveau métabolique du porc en croissanceDie metabolische körpergrösse des wachsenden schweines

The variation of metabolic rate with body weight (W) is reduced to a minimum when metabolic rate is related to W^b, the metabolic body size. The value of the exponent b is determined for three separate sets of experimental results on the pig within the W range of 20–90 kg, at different levels of metabolizable energy intake. It is concluded from these analyses that for intraspecific use in the pig it is more appropriate to use an exponent that is lower than the value of 0.75 commonly used for interspecific comparisons.     

Semen quality after vasectomy in the ramQualité du sperme du bélier vasectomiséde]Samenqualität nach vasektomie beim schafbock

Twenty four yearling rams which were trained for use with the artificial vagina were used to study changes in the volume, motility and density of ejaculates collected between 3 h and 6 days after vasectomy. Control rams underwent sham operations. On the day of vasectomy only, there was a decrease in the speed of ejaculation and an increase in sniffing and pawing activity.Ejaculate volume was unaffected by sham operation, but declined by 40–50% to 0.23–0.62 ml after vasectomy (P < 0.05).Irrespective of the timing of semen collections, motility declined to zero by the third ejaculate after vasectomy and density at that point had fallen to less than 0.1 × 10⁹ sperm/ml (less than 7% of pre-vasectomy levels).It is concluded that rams should be ejaculated at least 3 times after vasectomy if semen quality is to be reduced to the low levels normally associated with sterility, and that if rams are required for immediate use this may be achieved on the day of vasectomy.     

Immunization against 5α-androstenone in boarsL'immunisation contre la 5-androsténone chez le verratImmunisierung gegen 5α-Androstenon in Ebern

The effects of specific immunization against 5α-androstenone have been examined in large, genetically homologous groups of boars reared either to bacon weight (90–95 kg live weight) or to heavy manufacturing weight (115–120 kg live weight). At the lighter weight, immunization significantly (P < 0.05) reduced the concentration of androstenone in the adipose tissue from a mean value of 1.77 (S.E. 0.2) μg g^?1 fat in untreated boars (n=39) to 1.10 (S.E. 0.18) μg g^?1 for animals (n=19) treated with 5α-androstene-3-BSA. In contrast, boars (n=20) treated with 5α-androstenone-11-BSA as immunogen accumulated androstenone to a level of 1.99 μg g^?1 fat (S.E. 0.38). At the heavier weight, immunization reduced the accumulation of androstenone in adipose tissue from a mean value of 1.81 μg g^?1 fat (S.E. 0.22) in untreated boars (n=76) to 1.17 μg g^?1 (S.E. 0.19) for animals (n=22) treated with androstene-3-BSA as immunogen. In contrast, boars (n=21) treated with androstenone-11-BSA as immunogen accumulated androstenone to a mean level of 1.74 μg g^?1 fat (S.E. 0.46). No detrimental side-effects were observed in the immunized animals and the advantages of male-type performance and carcass composition were fully preserved.     

The net energy value of crude (catabolized) protein for growth in pigsValeur énergétique nette des matières grasses pour la croissance du porcDer nettoenergiewert von rohprotein (katabolisiert) für das wachstum bei schweinen

An experiment was performed with 36 growing pigs of Danish Landrace, to study the influence of digestible crude protein on the energy excretion with the urine and on the efficiency of utilization of metabolizable energy.The pigs (3 litters of females and 3 litters of male castrates) were distributed on six dietary treatments on a within-litter basis, taking into account the live weight of the pigs. The daily intake of the different diets was adjusted in such a way that the daily gain in the different treatment groups was almost identical through the entire experimental period from 20–90 kg.Three digestibility and nitrogen balance experiments were performed with each pig. At approximately 90 kg live weight the pigs were killed, dissected, ground, mixed and chemically analysed. The energy loss in urine increased by 4.9 kJ and the efficiency of utilization of metabolizable energy was decreased by approximately 6.6 kJ/g of catabolized protein.Digestibility experiments with ileo-caecal cannulated pigs indicated that the proportion of the digested energy disappearing in the caecum-colon increased with increasing dietary concentration of crude protein.     

Effects of breed and ejaculate volume on sperm morphology and semen parameters of boars

The aim of the study was to determine the relation between the semen quality, frequency of sperm defects, sperm dimensions and shape, and the ejaculate volume of Large White and Landrace boars. A total of 648 ejaculates collected from 31 Large White and 30 Landrace boars were divided into three groups according to the criterion of the ejaculate volume. In this study Landrace boars produced ejaculates with higher volume, sperm concentration, and total numbers of spermatozoa than Large White boars. Landrace boars also showed a lower frequency of sperm with morphological abnormalities (P < 0.05). Landrace boars sperm had larger heads, which were by 0.15 μm longer, and by a larger perimeter and area (P < 0.05). Landrace boar spermatozoa also had a longer flagellum and were generally larger and by 2.07 μm longer than Large White boar sperm (P < 0.05). Significant differences were also found in the shape of sperm of the two breeds (P < 0.05). Landrace boars sperm had more elongated heads, and the ratio of head size to flagellum length was lower than in Large White boars sperm (P < 0.05). Sperm from ejaculates with low volume had a shorter flagellum and a greater head length/flagellum length ratio than sperm from medium- and high-volume ejaculates (P < 0.05).     

Comparative susceptibility of indigenous and improved pig breeds to Classical swine fever virus infection: Practical and epidemiological implications in a subsistence-based, developing country setting

This study investigated the comparative susceptibility of indigenous Moo Laat and improved Large White/Landrace pig breeds to infection with classical swine fever virus (CSFV) under controlled conditions in the Lao People’s Democratic Republic (Lao PDR). The Moo Laat (ML) and Large White/Landrace crossbreed (LWC) pigs were inoculated with a standard challenge strain designated Lao/Kham225 (infectivity titre of 10^2.75 TCID₅₀/ml). The results demonstrated that both the native breed and an improved pig breed are fully susceptible to CSFV infection and the mortality rate is high. LWC pigs demonstrated lower (or shorter) survival times (50% survival time: 11 days), earlier and higher pyrexia and earlier onset of viraemia compared to ML pigs (50% survival time: 18 days). In the context of village-based pig production, the longer time from infection to death in native ML pigs means that incubating or early sick pigs are likely to be sold once an outbreak of CSF is recognized in a village. This increased longevity probably contributes to the maintenance and spread of disease in a population where generally the contact rate is low.     

山西地区6个猪种氟烷敏感基因的检测

采用PCR-RFLP技术对大白猪、长白猪、杜洛克猪、山西白猪、山西黑猪和马身猪等6个品种（系）482头猪进行了氟烷敏感（Hal）基因检测。结果表明,在山西黑猪和马身猪中,只检测到氟烷敏感阴性纯合子（NN）;而在长白猪、大白猪、杜洛克猪和山西白猪群体中,均检测到NN、Nn两种类型的个体,Haln的基因频率分别4.1%、1.8%、1.4%和1.7%。在今后的育种工作中,应加强对氟烷敏感基因的检测,选育抗应激群体。     

Selection potential of different prolificacy traits in the finnish landrace and large white populations

Heritabilities and genetic correlations for different prolificacy traits were estimated to assess possibilities of selection for high number of piglets weaned. Three litter-size traits: total number of piglets born (TNB), number of piglets born alive (NBA), number of piglets weaned (NW); four piglet survival traits: number of stillborn piglets (NSB), percent of stillborn piglets (NSB%), piglet mortality between birth and weaning (PM), percent of dead piglets during suckling (PM%); and three traits measuring time intervals: age at first farrowing (AFF), first farrowing interval (FFI), and gestation length (GL) were analysed. The Finnish national litter recording scheme provided data on the first parity litters of 11 329 Landrace and 8 362 Large White pigs born between 1986 and 2000. The heritabilitiy estimates were moderate for AFF and GL (0.24–0.37), and low for all the other traits (0.03–0.11). The genetic correlations between TNB and PM (0.68 in Landrace and 0.43 in Large White) and between NBA and PM (0.64 in Landrace and 0.31 in Large White) suggest that selection only for high TNB or NBA will lead to increased PM. The results showed further that GL will increase indirectly if the selection pressure is for low PM (r _g =?0.050 in Landrace and ?0.43 in Large White.