The preference of the consumer for pork from homozygous or heterozygous halothane negative animals.

To evaluate the taste preference of the consumer for meat from homozygous (NN) halothane negative pigs or heterozygous (Nn) halothane negative pigs, a consumer test was conducted at the "Agriflora" exhibition, concerning Flemish agriculture and horticulture, held from 8 to 10 January 1999 in Ghent, Belgium. The carcass quality of both tested genotypes was similar, while acidity, colour and drip loss were inferior and cooking loss and Warner-Bratzler shear force superior for the Nn pigs compared with the NN pigs. One hundred and seventy-one visitors completed the test correctly. No significant difference was found between NN- and Nn-meat for the tastiness scores. These results do suggest that elimination of the halothane gene from the pig population does not guarantee a better eating quality of the meat.

Relationship between fat depots in carcasses of beef bulls and effect on meat colour and tenderness.

Four hundred and thirty-three double-muscled and two hundred and two non-double-muscled Belgian Blue bulls, with mean cold carcass weights of 470±27 and 414±33 kg, respectively, were studied to investigate the relationships between the SEUROP fat grade, the anatomical fat content in the carcass (adipose tissue) and the chemical fat content in the Longissimus thoracis. The relationships between the shear force value and the lightness of the meat and fat characteristics were also studied. A moderate correlation was found between the fat characteristics within each data set with correlation coefficients, ranging from 0.4 to 0.6. The correlation coefficients increased to 0.70-0.85 when the data sets were pooled. Fat characteristics of the carcass and meat showed only limited predictive power (R(2)<0.15) for meat tenderness and colour. This study also shows that double-muscled animals belong to a sub-population of the Belgian Blue breed rather than deviants from the non-double-muscled animal.

Incorporation of dietary polyunsaturated fatty acids into pork fatty tissues.

The incorporation and elimination rate of dietary PUFA in pork fat was investigated in this study. Experiment 1 examined the incorporation of dietary PUFA into backfat (BF) and into the triglyceride (TG) and phospholipid (PL) fractions of the i.m. fat of the loin. Experiment 2 examined the elimination of PUFA from BF due to withdrawal of PUFA from the diet. In Exp. 1, Piétrain x Seghers Hybrid pigs (70 barrows and 70 gilts averaging 11 wk of age and 30 kg initially) were assigned to five dietary treatments in a 2 x 5 factorial arrangement during a 16-wk feeding period. Pigs received a diet containing about 2.5% tallow (T) for 8, 10, 12, 14, or 16 wk, followed by a diet containing about 15% full-fat soybeans (FFS) for 8, 6, 4, 2, or 0 wk, respectively. Additionally, BF biopsies were taken every 2 wk from eight pigs on the 8-wk FFS dietary treatment, starting from the time pigs were switched to the FFS diet. Linoleic acid [18:2(n-6)], linolenic acid [18:3(n-3)], eicosadienoic acid [20:2(n-6)], arachidonic acid [20:4(n-6)], and PUFA contents in BF increased (P < .01) with time on the FFS diet, but contents of these fatty acids were similar for pigs fed FFS for 6 or 8 wk. The PUFA content of the biopsies rose throughout the FFS treatment; the greatest increase in PUFA occurred during the first 2 wk of feeding FFS. The PUFA content of the TG and PL fractions in i.m. fat of the longissimus muscle tended to increase with time on the FFS diet. The increase was significant (P < .01) in the TG fraction for 18:3(n-3) and in the PL fraction for 20:4(n-6) and 22:6(n-3). In Exp. 2, 11-wk-old pigs (10 barrows and 10 gilts) were fed a FFS-based diet from 11 to 19 wk of age, followed by the T-diet for an additional 8 wk. During the latter period, biopsies were taken every 2 wk. The elimination of PUFA from BF was greatest during the first 2 wk after the dietary change. The PUFA reached the lowest level at the age of 25 wk. These experiments show that the PUFA: saturated fatty acid ratio of BF can be increased from .34, corresponding with a T-based diet, to .55, by feeding a FFS diet for 6 wk before slaughter.

Evaluation of the physical structure of fodder beets, potatoes, pressed beet pulp, brewers grains, and corn cob silage.

The physical structure of fodder beets, raw potatoes, ensiled pressed sugar beet pulp, ensiled brewers grains, and corn cob silage was evaluated in diets containing concentrates and either corn silage or grass silage as the roughage source. In one series of experiments, the chewing activity of eight cows was measured over 4 d. The beet pulp and fodder beets were added to the two roughage sources at two ratios [20:80 and 35:65, dry matter (DM) basis]. Potatoes, brewers grains, and corn cob silage were fed in a fixed amount (5 to 6 kg of DM) with corn silage. The chewing indexes (eating and ruminating time per kilogram of DM ingested) for fodder beets and beet pulp averaged 34.3 and 32.3 min/kg of DM, respectively, and were hardly affected by the nature of the roughage or by the inclusion ratio. The chewing indexes for potatoes, brewers grains, and corn cob silage were 23.7, 56.6, and 41.6 min/kg of DM, respectively. In another series of experiments using 8 to 11 cows, the ratio of roughage to concentrates was lowered weekly by 5 percentage units, and the critical rough-age portion of the diet was determined (i.e., the amount just before a lack of physical structure was observed). The roughage source was either fed alone or supplemented with about 4 kg of DM of the experimental feed. The critical roughage portion of the diet decreased when the experimental feeds were added; the decrease was greatest with ensiled pressed beet pulp and was lowest with corn cob silage.

Estimation of chemical carcass composition from 8th rib characteristics with Belgian blue double-muscled bulls.

Characteristics from the 8th rib cut: chemical composition, tissue composition after dissection, specific gravity (SG) and m. longissimus thoracis (LT) composition, collected on 17 Belgian Blue double-muscled fattening bulls were used to generate equations for predicting chemical carcass composition. Carcass composition was best predicted from chemical analysis of the 8th rib cut and the empty body weight (EBW) of the bull. Carcass chemical fat content (CCF, kg) was predicted from the 8th rib cut fat content (ether extract, 8RF, kg) by the following regression: CCF=1.94+27.37 8RF (R(2)=0.957, RSD =9.89%). A higher coefficient was found for carcass water (CCW, kg) predicted from 8RF and EBW: CCW=-2.26+0.28 EBW-34.28 8RF (R(2)=0.997, RSD=1.48%). No parameter was found to improve the prediction of CCP from EBW solely: CCP=-0.86+0.08 EBW (R(2) =0.992, RSD=2.61%). Prediction equations based solely on LT composition had low R(2) values of between 0.38 and 0.67, whereas no significant equations were found using SG. However, equations based on EBW had R(2) values between 0.78 and 0.99. Chemical components of the 8th rib cut in combination with EBW are most useful in predicting the chemical composition of the carcass of Belgian-Blue double-muscled bulls.

Comparison of different methods for measuring water holding capacity and juiciness of pork versus on-line screening methods.

The extent to which water holding capacity (WHC) techniques: filter paper press method, drip loss and filter paper method, are related to the sensory juiciness appreciation of pork was studied. Additionally four on-line methods: pH1, FOP1 (light scattering), PQM1 (conductivity) and DDLT (Double Density Light Transmission), were evaluated for their ability to predict WHC and juiciness scores. One-hundred and twenty samples of m. longissimus thoracis et lumborum, from animals of different genotypes, were involved in this study. Only WHC results, determined by the filter paper press method, were significantly correlated with juiciness scores (r=-0.24). The results of the filter paper method, either by weighing or visual judging, could not be predicted by the on-line methods. The results of the filter paper press method (F.p.p.-RZ) and drip loss were slightly better correlated with DDLT (respectively, r=0.56 and 0.45) than with PQM1 (r=0.51 and 0.36), FOP1 (r=0.48 and 0.34) and pH1 (r=0.41 and 0.34), although the standard error of estimate of the linear regressions was similar for the four on-line methods. Unfortunately, the on-line techniques incorrectly predicted several WHCs. Juiciness was slightly or not related to the on-line methods. The DDLT technique, which is analogous to the CGM (Capteur Gras/Maigre), an officially accepted carcass grading apparatus in France and Belgium, is as good or better than the classical on-line instruments: pH, FOP and PQM, in predicting WHC.

Measurement and prediction of pork colour.

The extent to which instrumental colour determinations by FOPu (light scattering), Göfo (reflectance) and Labscan II (CIE L*, CIE a* and CIE b*, hue and chroma) are related to the Japanese colour grades was studied. Additionally, four on-line methods: pH1, FOP1, PQM1 (conductivity) and DDLT (Double Density Light Transmission, analogous to Capteur Gras/Maigre), were evaluated for their ability to predict subjectively and objectively colour. One hundred and twenty samples of m. longissimus thoracis et lumborum, from animals of different genotypes, were analysed. Of the instrumental colour determinations, CIE L* (r=-0.82), FOPu (r=-0.70) and Göfo (r=0.70) were best correlated with the Japanese colour scores. The Japanese colour grades could be predicted by the on-line instruments, pH1, FOP1, PQM1 and DDLT, with determination coefficients between 15 and 28%. Ultimate meat colour, determined by Japanese colour standards, FOPu, Göfo and CIE L*, was better predicted by DDLT than by the classic on-line instruments: FOP1, pH1 and PQM1, although the standard error of the estimate was similar for all instruments. This means that DDLT, although originally designed for estimating lean meat percentage, can additionally give information about meat quality, in particular colour. However, it must be stressed that the colour estimate by DDLT refers to a population of animals, rather than to individual pigs, because of the number of erroneously assigned samples.

Consumer perception, facts and possibilities to improve acceptability of health and sensory characteristics of pork.

Changes at consumer level, as well as an image decline of the meat sector, resulted in considerable decreases of fresh meat consumption. Consumer orientation is considered as a prerequisite to slow down or reverse the adverse fresh pork consumption evolution. Consumer perception of pork is taken as the starting point of this article. Focus is first on assessing differences between facts related to nutritional value and healthiness aspects of pork and their perception by Belgian meat consumers. Second, possibilities of improving pork characteristics are identified. Pork is perceived worst as compared to beef and poultry on the attributes leanness, healthiness, taste and tenderness. Consumer-oriented response strategies should focus at improving these intrinsic quality characteristics, before other elements like traceability, labelling or marketing can be implemented successfully. The possibilities to improve nutritional value, healthiness and sensory characteristics pertain to selection, pig diet composition, transport, slaughter and post-slaughter circumstances. A successful adoption of consumer orientation urges for co-operation throughout the entire pork production chain. The identified topics are key attention points for adequate production and marketing by the pork sector, as well as for consequent communication by government and public services.

Pork tenderness estimation by taste panel, Warner-Bratzler shear force and on-line methods.

The extent to which modification of Warner-Bratzler shear force (WBSF) determinations, relating to storage and preparation of the meat, aperture of the V-shaped cutting blade and shearing velocity, improve the relationship with sensory tenderness perception of pork was studied. Additionally four on-line methods: pH1, FOP1 (light scattering), PQM1 (conductivity) and DDLT (Double Density Light Transmission), were evaluated for their ability to predict tenderness. Sensory tenderness evaluation was conducted on 120 frozen (at -18°C for several months) samples of m. longissimus thoracis et lumborum. After overnight thawing, the meat was grilled to an internal temperature of 74°C and scored on an eight-point scale, from extremely tough to extremely tender. The standard WBSF procedure (protocol A) consisted of heating fresh meat samples (stored for 48 h at 4°C post slaughter) at 75°C for 50 min, cooling in cold tap water for 40 min, taking cylindrical cores parallel to the fibre direction, and shearing at a velocity of 200 mm/min with a blade aperture of 60°. For the prediction of sensory tenderness, the WBSF standard procedure (protocol A) showed the lowest variance (R(2)=15%) and the highest standard error of the estimate (SEE=0.97 N) compared to the other WBSF protocols. A decrease in shearing velocity, from 200 to 100 mm/min and, a replacement of the cutting blade with an aperture of 60° by one with an aperture of 30° led to improvements of R(2) (respectively, 19% vs. 13% and 47% vs. 23%) and SEE (respectively, 0.93 N vs. 0.97 N and 0.80 N vs. 0.97 N) and thus were better predictors of tenderness. A blade aperture of 30° instead of 60° also led to considerably lower WBSF values (22.1 N vs. 30.0 N). Freezing, frozen storage and thawing of the meat, prior to WBSF measurement, resulted in higher shear force values (32.7 N vs. 28.7 N) and a better prediction of tenderness, R(2) (25% vs. 15%) and SEE (0.94 N vs. 1.00 N). Furthermore, preparing the frozen stored meat for WBSF determination in the same way as for the sensory evaluation, namely grilling instead of boiling, led to higher WBSF values (35.5 N vs. 32.7 N) and a further improvement in the prediction of tenderness (R(2)=31% vs. 25% and SEE=0.90 N vs. 0.94 N). From the on-line instruments: pH, FOP and PQM, pH was best in predicting tenderness. Linear regression with tenderness as dependent variable and the on-line techniques as independent variables revealed the following R(2): 16, 8, 8 and 10% and SEE: 0.96, 1.01, 1.01 and 1.00 N for, respectively, pH1, FOP1, PQM1 and DDLT. Thus, the classical instruments and the DDLT technique, which is analogous to the CGM (Capteur Gras/Maigre), an officially accepted carcass grading apparatus in France and Belgium, are not good predictors of tenderness.

Effect of incorporation of dietary polyunsaturated fatty acids in pork backfat on the quality of salami.

The suitability of backfat high in polyunsaturated fatty acids (PUFA) for salami manufacture was assessed. Eighty pigs (barrows and gilts) were fed four diets, containing 21, 25, 28 and 28 g PUFA/kg feed, originating mainly from soybeans and/or soybean oil in the first three diets and from linseed in the fourth. Salami was prepared with backfat from these pigs, according to gender and dietary treatment. Samples were taken throughout the ripening. The taste panel rejected the two high PUFA (diet 3 and 4) levels; moreover fishy off-flavours were detected for dietary treatment four. Twenty-five grams PUFA/kg feed, corresponding with 23% PUFA in backfat or 15% PUFA in salami, results in acceptable taste, if linoleic acid is the predominant PUFA. However, all PUFA levels resulted in salamis too soft to be commercialized, as evidenced by a fatty film on the salami slicing machine.

Omega-3 fatty acids in pig nutrition: implications for zootechnical performances, carcass and fat quality.

The extent of incorporation of dietary alpha-linolenic acid -readily available in linseed- in pig diets, in view of repercussions on zootechnical performance, carcass and fat quality of pigs, is investigated. Ninety hybrid pigs (Piétrain x Seghers hybrid cross, 41 barrows and 49 gilts), divided in three comparable groups, were fed ad libitum three experimental diets, containing respectively 4 g, 7 g and 10 g alpha-linolenic acid per kg feed, originating from linseed. The increase of polyunsaturated fatty acid content in the feed (11.9 g, 15.2 g and 18.8 g per kg feed, resp.) could almost be completely attributed to the variation in alpha-linolenic acid. Despite several anti-nutritional factors, present in linseed, zootechnical performance was not affected by the diet. However, carcass quality, in terms of lean meat % and conformation, was less favourable for the highest linseed level compared to the intermediate level. Loin fat thickness was not influenced by the fat source in the diet. More pronounced was the effect of sex on zootechnical and carcass parameters: gilts showed a lower feed intake and weight gain, resulting in a more favourable feed conversion ratio, a thinner backfat layer, a higher meat content and a superior conformation, compared to the barrows. The linolenic acid content in the backfat increased from 3.1 g to 6.8 g per 100 g of total fatty acids for the barrows and from 3.4 g to 7.0 g per 100 g of total fatty acids for the gilts. A significant positive correlation was found between the live weight at slaughter and C16:0 and C18:0 content in the backfat; C18:2 and C20:4 content, on the contrary, were negatively correlated with the live weight at slaughter. A more unsaturated fatty acid pattern of the backfat, as a result of higher C18:3 levels in the feed, resulted in higher TBA-values (thiobarbituric acid), without occurrence, though, of off-odours during the fat thawing. Thus PUFA content in the backfat reached a maximum of respectively 18 g and 19 g per 100 g of total fatty acids for the barrows and the gilts, without implications for the consistency of the fat.

Omega-3 fatty acids in pig nutrition: Implications for the intrinsic and sensory quality of the meat.

Seventy-eight hybrid pigs (Piétrain × Seghers hybrid cross, 38 barrows and 40 gilts) were fed ad libitum diets, containing either 0.4%, 0.7% or 1.0% α-linolenic acid (C18:3n-3), originating from linseed. The variation in polyunsaturated fatty acid content in the feed (1.19%, 1.52% and 1.88%, respectively) was mainly attributed to variations in α-linolenic acid content. Meat quality evaluated by physical measurements (pH, light scattering, conductivity, colour, light reflection, tenderness, water holding capacity) was not influenced, to any significant extent, by the fatty acid composition of the feed. A subjective judgement of cohesiveness revealed no abnormalities. Dietary fat source, sex and intramuscular fat (IMF) level affected the fatty acid pattern of the IMF. The α-linolenic content in the IMF increased from 1.2% to 2.3% for the barrows and from 1.4% to 2.9% for the gilts with increasing αlinolenic acid content in the feed. A multiple paired comparison test for taste, tenderness and juiciness on 45 meat samples (M. longissimus thoracis) revealed no significant differences among the feed groups.

Incorporation of dietary polyunsaturated fatty acids in pork tissues and its implications for the quality of the end products.

One hundred and ten fattening pigs of a Piétrain × Hybrid cross-barrows and gilts in equal numbers-were distributed over five feeding formulas, containing increasing amounts of polyunsaturated fatty acids (PUFA), in the form of rapeseed. The aim of the study was to evaluate the maximum admissible amount of PUFA in the pig diet before problems-in terms of backfat consistency and storage stability-occur and to investigate the incorporation of dietary PUFA in intramuscular fat as well. A tendency towards reduced feed (energy) intake was obvious from the 7% rapeseed inclusion level, apparently resulting in a somewhat thinner backfat layer. None of the backfat samples showed a visible yellow discolouration instead thin backfat layers appeared as pink. Backfat consistency was lower for gilts and decreased with increasing dietary PUFA levels. PUFAs in the feed and in backfat were very well correlated (0.8-0.9) as expected; correction for de novo fat synthesis (by means of backfat thickness) did not alter the correlations within one sex group. Thresholds for PUFA in feed-15 g PUFA/kg feed-and for PUFA in back-fat-iodine value of 70 or 15% PUFA-were all surpassed in this experiment: 18 g PUFA/ kg feed resulted in maximally 22% PUFA in the outer backfat layer. The backfat PUFA limit was reached at relatively low feed PUFA levels. This might be explained by thin and hence more unsaturated backfat layers in lean or underweight pigs. Oxidative stability of the backfat after storage for 1 year in the freezer was satisfactory. The total intramuscular fat (IMF) content showed no obvious relationship with diet, in contrast with sex: barrows had more IMF than gilts. IMF consisted in 80% apolar phase and 20% polar fraction. The apolar fraction showed similar feed and sex tendencies as backfat, although correlations between feed and apolar fraction PUFAs were higher for gilts than for barrows. The amount of phospholipid was invariable throughout all treatments. Only linoleic acid-the major fatty acid-showed some feed and sex influence. In view ofthf results obtained the threshold for feed and backfat PUFA can be as high as, respectively, 18 g PUFA/kg feed and 22% PUFA in backfat, without deterioration of fresh and frozen backfat. However, for meat processing, demands could be more severe.

Effect of yeast supplementation on health, performance and rumen fermentation in beef bulls.

The effect of 0, 6 or 60 g yeast (Saccharomyces cerevisiae) daily on health and performance was investigated in 90 double-muscled and 48 non-double-muscled Belgian White-blue bulls during 60 and 51 days, respectively, upon arrival at the experimental farm. The yeast was incorporated in the concentrate, which was fed at 2 kg d-1 during the first ten days and at 2.5 kg d-1 afterwards. Besides, maize silage was fed up to 8 kg d-1, while grass hay was offered ad libitum. Feed intake, growth rate and number of sick animals were not affected by the yeast addition. Morbid animals required a similar number of days with antibiotic therapy for each yeast level within each beef strain. Rumen samples taken from 6 non-double-muscled bulls in the last but one week showed a decreased concentration of volatile fatty acids when 6 g yeast was fed daily. Except butyric acid concentration, rumen fermentation parameters were not altered. Yeast supplementation during an adaptation period after purchase did not affect health status and growth performance.

The relationship between carcass, meat and eating quality of three pig genotypes.

The relation between the intrinsic carcass and meat quality and the organoleptical characteristics of three genotypes of pigs was studied. In total 411 pigs, consisting of 121 BL-genotype pigs, 115 hybrids (Seghers Hybrid) and 175 Large White-genotype pigs, were screened. Slaughter day and genetic background had a great impact on the intrinsic meat quality parameters. The factor 'slaughter day' implies the stunning method besides the total specific transport and slaughter conditions. Whatever the genetic background is, halothane susceptibility is obviously the crucial factor. Selection against the halothane gene positively influences the intrinsic and sensory meat quality parameters. This study also suggests that an increase in the intramuscular fat content, if desirable in the interest of the sensory meat quality, can be achieved without deterioration of the zoo-technical performance and the carcass quality of the pigs.

Beet fed as such or ensiled with maize and fresh potatoes in diets for finishing bulls.

The use of beet for beef production after ensiling together with maize was studied in two experiments involving 112 and 114 White-blue bulls. In the first experiment maize silage (I) was compared with mixed silage of maize and fodder beet (II) or sugar beet (III) (ratio: 2/1, DM-basis). In the second experiment maize silage (I) was compared with mixed silage of 0.67 maize and 0.33 sugar beet (II) or maize silage and fresh sugar beet (ratio: 2/1, DM basis) (III) or fresh sugar beet and potatoes afterwards at 4% of the live weight and maize silage (IV). From day 113 onwards, mixed silage was also fed to group III and sugar beet were replaced by raw potatoes in group IV. The basic diet was always supplemented with concentrate at 0.75% of the live weight. In experiment 1 live weight gain was slightly but not significantly higher for the mixed silages, although daily net energy intake per kg metabolic weight was higher. Feed efficiency was not significantly different among groups. Mixed silages yielded more fat in the carcass. In the second experiment initial growth rates were not significantly affected by the use of sugar beet or mixed silages. Afterwards, they were increased in comparison with maize silage. Also in this experiment, daily net energy intake was increased by sugar beet, or by potatoes. Energy efficiency did not differ among groups. This experiment did not show significant differences for the carcass composition. However, EUROP fatness score was higher for diets containing one third sugar beet. Most meat quality parameters were not affected by the diets. Only the lightness was different between III and IV.

Effect of duration of a beta-agonist treatment on growth, feed intake and carcass characteristics in finishing bulls.

Two experiments were conducted to study the effect of a different duration of dietary cimaterol on animal performances and carcass characteristics in finishing Belgian White-blue bulls. They received a concentrate diet ad libitum during 228 days on average, containing no cimaterol (control) or 4 ppm cimaterol during 71, 127 or 246 days (experiment 1) or during the last 76, 108 or 136 days before the end of the fattening period (experiment 2). Prior to slaughter a 6-day withdrawal period was applied. There was a significant increase in the growth rate immediately after the onset of the cimaterol feeding. A long-term cimaterol administration of 4.5 to 8 months tended to decrease daily gain towards the end of the experiment. Average daily feed intake was only slightly reduced when cimaterol was fed from the beginning of the experiment. Feed conversion was improved by cimaterol, but the effect was smaller after a long-term administration. Increased Longissimus dorsi area and hindleg width revealed muscle hypertrophy in cimaterol-treated bulls. Dressing percent and carcass meat content were increased. Optimum duration of 4 ppm dietary cimaterol varied between 2.5 and 4 months.

Serum pyruvate kinase and its relation to stress susceptibility in pigs.

SUMMARY: Four blood tests, complementary to the halothane test, have been screened for their capacity to discriminate between homozygous and heterozygous stress resistant and stress susceptible pigs: TBARS in plasma, lipid peroxides from erythrocytes and plasma creatine and pyruvate kinase activity. Blood samples were collected from homozygous (NN) and heterozygous (Nn) stress resistant and homozygous stress susceptible (nn) pigs, while subjected to the halothane test. Serum creatine kinase and pyruvate kinase tests were retained for a more elaborated study. Pyruvate kinase appears to be a more reliable indicator of stress susceptibility than the well-known creatine kinase. However both parameters display a considerable standard deviation. Consecutive assays show the pyruvate kinase activity to be dependent on age (weight), which accounts for part of the variation; other sources of variation are the conditions of the exeriment and the way the imposed stress is perceived by the animal. During this experiment a rapid and accurate DNA-test for HAL-genotype detection has been developed (Fujii et al. 1991; Otsu et al. 1991; Coppieters et al. 1992). In spite of this, the pyruvate kinase parameter is a much more discriminating and remarkable indicator for stress susceptibility than the, in previous years, widely used creatine kinase test. ZUSAMMENFASSUNG: Serum Pyruvat Kinase und seine Relation mit Streßanfälligkeit bei Schweinen Vier Blutteste, komplementär dem HAL-Test, wurden in einem Screening-Verfahren untersucht um homozygote und heterozygote streßresistente und streßanfällige Schweine zu differenzieren: TBARS in Plasma, Lipid Peroxyde von Erythrocyten und Plasma Kreatine und Pyruvat Kinase Aktivität. Während des Halothantestes wurde Blut entnommen von homozygoten (NN) und heterozygoten (Nn) streßresistenten und homozygoten streßanfälligen Schweinen (nn). Mit Serum Kreatine Kinase und Pyruvat Kinase Aktivität Tests wurden eine umfassende Überprüfung durchgeführt. Letztere zeigt sich als ein zuverlässiger Indikator der Streßanfälligkeit als die wohl bekanntere Kreatine Kinase. Mehrmalige Analysen zeigen, daß Pyruvat Kinase Aktivität vom Alter (Gewicht) abhängig ist, was teilweise die Variabilität verursacht; andere Quellen der Variabilität sind die experimentellen Umstände und die Weise, wie der auferlegte Streß durch das Tier erfahren wird. Während der Durchführung dieses Experimentes wurde ein schneller und akkurater DNA-Test für HAL-Genotyp Detektion entwickelt (Fujii et al. 1991; Otsu et al. 1991; Coppieters et al. 1992). Im Vergleich mit dem, in vorgehenden Jahren, häufig angewendeten Kreatine Kinase Test, ist der Pyruvat Kinase Parameter trotzdem ein bemerkenswerter und diskriminierender Indikator für Streßanfälligkeit.

Effect of grain processing on in sacco digestibility and degradability in the rumen.

Effect on nylon-bag digestibility of rolling and steam-flaking as such or followed by grinding through a 1-mm screen was studied in wheat, barley and maize grains. Digestibilities of ground grains were not different, irrespective of rolling or steam-flaking, except flaked and ground barley, which was less digestible than ground barley. Rolled and flaked grains were less digestible than ground grains, except for rolled wheat which was not different from ground wheat. These results suggest that particle size due to grinding is more important than other methods of processing. Dry matter and protein degradabilities of steam-flaked grains were investigated by in sacco technique and compared with unprocessed grains. Dry matter degradability during incubation periods up to 24 h was reduced for steam-flaked wheat and barley, but increased for flaked maize. Protein degradability was lower for flaked grains.

Effect of virginiamycin on in vivo digestibility, rumen fermentation and nitrogen balance.

Three experiments were conducted to investigate the effect of virginiamycin. Digestibility was determined with wethers, fed a diet of 0.65 maize silage and 0.35 concentrate on a dry matter basis (Experiment I) or a complete dry feed (Experiment II) at maintenance, and with growing bulls fed a maize silage diet ad libitum supplemented with 7.5 g concentrate per kg live weight (Experiment III). Virginiamycin was incorporated at 0 or 65 ppm in the concentrate and 0 or 25 ppm in the complete dry feed. No significant effect on dry or organic matter digestibility was observed, although digestibilities of protein and ether extract were reduced by virginiamycin in experiments I and II, respectively. Rumen fermentation was studied in experiments I and II. Virginiamycin increased acetic acid concentration and reduced butyric acid concentration in experiment I, but exerted no significant effect in experiment II. An interaction between diet type and virginiamycin was found for the C2/C3 ratio. Nitrogen balance, measured in experiment III, was not affected by virginiamycin.