NN Animals Research Articles

Performance and enteric methane emission of growing beef bulls from different genetic groups subjected to two supplementation strategies grazing tropical grass in the rainy season

Improving livestock production through nutrition and breeding can increase efficiency and has the potential to mitigate methane (CH4) emissions. Additionally, supplementing beef cattle in the rainy season balances the dietary protein:energy (P:E) ratio, which can increase animal performance and reduce energy losses from CH4 production. Therefore, the objective of this study was to evaluate the effect of supplementation strategy (SS) and genetic group (GG) on the intake, digestibility, performance, and enteric CH4 emissions of growing beef bulls grazing tropical grass during the rainy season. One hundred sixty-two growing beef bulls averaging (mean ± SD) 10 ± 2 months old and 262 ± 31 kg of initial body weight (BW) were distributed, according to their BW, in a randomized complete block design in a 2 × 3 factorial arrangement. Factors included (1) two SSs (mineral supplementation at 0.3 g/kg of BW per day and a corn-based supplementation at 3 g/kg of BW per day) and (2) three GGs (Nellore [NN], ½Senepol½Nellore [SN], and ½Angus½Nellore [AN]). Animals were allocated in 12 paddocks composed of Urochloa brizantha (A. Rich.) Stapf. cv. Xaraés for 99 days during the rainy season. Regardless of the GG, the intakes of total DM, supplement DM, OM, CP, aNDFom, EE, and NFC were increased in animals supplemented with a corn-based supplement. The SN bulls had a greater digestibility of DM, OM, and CP, and animals supplemented with a corn-based supplement had greater CP and EE digestibility. There was an interaction between GG and SS for NFC digestibility, which was decreased in AN animals fed a corn-based supplement. However, the corn-based supplementation improved the animal’s performance and carcass characteristics as demonstrated by the increase of final BW (kg), ADG (kg), REA (cm2), and FT (mm). Moreover, NN animals fed a corn-based supplement showed an increase in ADG (kg). An interaction between SS and GG was observed for GPH (kg/ha) and CaG (kg), with the greatest values observed in NN and SN animals supplemented with a corn-based supplement. Enteric CH4 emissions (g/d, g/kg of DMI, and g/kg of dOM) were lower in animals fed a corn-based supplement. A decrease in CH4 emissions (g/d) was observed in SN compared to NN animals. In addition, there was an interaction between SS and GG for CH4 emissions (g/kg of CaG), with the lowest values for NN and SN animals supplemented with a corn-based supplement. Taken together, our results demonstrate that corn-based supplementation is an effective nutritional strategy for use in the rainy season, especially for NN and SN genetic groups, to improve animal’s performance and carcass characteristics and to decrease enteric CH4 emissions, per unit of product, of growing beef bulls grazing tropical grass.

Maternal versus artificial rearing shapes the rumen microbiome having minor long-term physiological implications.

SummaryIncreasing productivity is a key target in ruminant science which requires better understanding of the rumen microbiota. This study investigated how maternal versus artificial rearing shapes the rumen microbiota using 24 sets of triplet lambs. Lambs within each sibling set were randomly assigned to natural rearing on the ewe (NN); ewe colostrum for 24 h followed by artificial milk feeding (NA); and colostrum alternative and artificial milk feeding (AA). Maternal colostrum feeding enhanced VFA production at weaning but not thereafter. At weaning, lambs reared on milk replacer had no rumen protozoa and lower microbial diversity, whereas natural rearing accelerated the rumen microbial development and facilitated the transition to solid diet. Differences in the rumen prokaryotic communities disappear later in life when all lambs were grouped on the same pasture up to 23 weeks of age. However, NN animals retained higher fungal diversity and abundances of Piromyces, Feramyces and Diplodiniinae protozoa as well as higher feed digestibility (+4%) and animal growth (+6.5%) during the grazing period. Nevertheless, no correlations were found between rumen microbiota and productive outcomes. These findings suggest that the early life nutritional intervention determine the initial rumen microbial community, but the persistence of these effects later in life is weak.

Effect of Polymorphisms at Codon 146 of the Goat PRNP Gene on Susceptibility to Challenge with Classical Scrapie by Different Routes.

This report presents the results of experimental challenges of goats with scrapie by both the intracerebral (i.c.) and oral routes, exploring the effects of polymorphisms at codon 146 of the goat PRNP gene on resistance to disease. The results of these studies illustrate that while goats of all genotypes can be infected by i.c. challenge, the survival distribution of the animals homozygous for asparagine at codon 146 was significantly shorter than those of animals of all other genotypes (chi-square value, 10.8; P = 0.001). In contrast, only those animals homozygous for asparagine at codon 146 (NN animals) succumbed to oral challenge. The results also indicate that any cases of infection in non-NN animals can be detected by the current confirmatory test (immunohistochemistry), although successful detection with the rapid enzyme-linked immunosorbent assay (ELISA) was more variable and dependent on the polymorphism. Together with data from previous studies of goats exposed to infection in the field, these data support the previously reported observations that polymorphisms at this codon have a profound effect on susceptibility to disease. It is concluded that only animals homozygous for asparagine at codon 146 succumb to scrapie under natural conditions.IMPORTANCE In goats, like in sheep, there are PRNP polymorphisms that are associated with susceptibility or resistance to scrapie. However, in contrast to the polymorphisms in sheep, they are more numerous in goats and may be restricted to certain breeds or geographical regions. Therefore, eradication programs must be specifically designed depending on the identification of suitable polymorphisms. An initial analysis of surveillance data suggested that such a polymorphism in Cypriot goats may lie in codon 146. In this study, we demonstrate experimentally that NN animals are highly susceptible after i.c. inoculation. The presence of a D or S residue prolonged incubation periods significantly, and prions were detected in peripheral tissues only in NN animals. In oral challenges, prions were detected only in NN animals, and the presence of a D or S residue at this position conferred resistance to the disease. This study provides an experimental transmission model for assessing the genetic susceptibility of goats to scrapie.

Influence of catch up growth on spatial learning and memory in a mouse model of intrauterine growth restriction.

BackgroundIntrauterine growth restriction (IUGR) and rapid postnatal weight gain or catch up growth (CUG) increase the susceptibility to metabolic syndrome during adult life. Longitudinal studies have also revealed a high incidence of learning difficulties in children with IUGR. The aim of the present study was to investigate the effect of nutrition and CUG on learning memory in an IUGR animal model. We hypothesized that synaptic protein expression and transcription, an essential mechanism for memory consolidation, might be affected by intrauterine undernutrition.MethodsIUGR was induced by 50% maternal caloric undernutrition throughout late gestation. During the suckling period, dams were either fed ad libitum or food restricted. The pups were divided into: Normal prenatal diet-Normal postnatal diet (NN), Restricted prenatal diet- Normal postnatal diet + catch up growth (RN+), Normal prenatal diet-Restricted postnatal diet (NR) and Restricted prenatal diet-Restricted postnatal diet (RR). At 4 weeks of age, memory was assessed via a water maze test. To evaluate synaptic function, 2 specific synaptic proteins (postsynaptic density-95 [PSD95], synaptophysin) as well as insulin receptors (IR) were tested by Western Blot and quantitative polymerase chain reaction (qPCR). Brain-derived neurotrophic factor and serum insulin levels were also studied.Results and conclusionsThe RN+ group presented a learning curve similar to the NN animals. The RR animals without CUG showed learning disabilities. PSD95 was lower in the RR group than in the NN and RN+ mice. In contrast, synaptophysin was similar in all groups. IR showed an inverse expression pattern to that of the PSD95. In conclusion, perinatal nutrition plays an important role in learning. CUG after a period of prenatal malnutrition seems to improve learning skills. The functional alterations observed might be related to lower PSD95 activity and a possible dysfunction in the hormone regulation of synaptic plasticity.

INFLUENCE OF BREED, SEX AND GROWTH HORMONE AND HALOTHANE GENOTYPES ON CARCASS COMPOSITION AND MEAT QUALITY TRAITS IN PIGS

ABSTRACT The objective of this study was to verify the influence of the growth hormone (GH) and halothane (Hal) genotypes, breed and sex on carcass and meat quality. Ninety‐six pigs (Piétrain, Large White and Landrace) were dissected. For each breed, 16 were noncastrated males and 16 were females. The Piétrain animals presented the greatest lean meat percentage, the heaviest ham and shoulder and the lightest belly weight and fat thickness. Landrace presented the heaviest belly. Females presented the greatest drip loss; L*, b* and fat thickness; the heaviest ham and loin; and the lightest shoulder and tenderloin. Hal–NN and Nn presented greater loin weight than nn animals. Nn animals presented smaller belly weight than homozygotes. The nn animals presented greater drip loss than NN and Nn, and greater lean meat than NN. Interestingly, GH–D2D2 animals also showed higher drip loss than those with D1D1 genotype. This investigation presents relevant associations between important economic traits and specific GH and Hal genotypes.PRACTICAL APPLICATIONSThe identification of new molecular markers related to pig production has been increasing in importance, especially when these markers are related to carcass and meat quality traits, which are difficult to predict. When a marker is intensively used in a selection program, it reaches fixation, so it is important to identify new markers to replace it. This work shows, for the first time, the association of a GH polymorphism with an important meat quality trait and reinforces the possibility of its use in programs of marker‐assisted selection.

Relationship between the Porcine Stress Syndrome gene and carcass and performance traits in F2 pigs resulting from divergent crosses

The PSS genotypes of 596 F2 pigs produced by initial mating of Brazilian native boars commercial sows and were characterized by PCR-RFLP and their carcass and performance traits were evaluated. Among the 596 animals analyzed, 493 (82.72%) were characterized as NN and 103 (17.28%) as Nn. With respect to carcass traits, Nn animals presented higher (p < 0.05) right half carcass weight, left half carcass weight, loin depth and loin eye area, and lower shoulder backfat thickness, backfat thickness between last and next to last but one lumbar vertebrae and backfat thickness after last rib at 6.5 cm from the midline compared to NN animals. Nn animals also showed (p < 0.05) higher values for most of the cut yields, indicating higher cutting yields for animals carrying the n allele and lower values for bacon depth, confirming lower fat deposition in carcass. In addition, Nn animals presented (p < 0.05) lower values for the performance trait weight at 105 days of age. These results indicate that animals carrying the PSS gene generate leaner carcasses, higher cut yields, and that the effects of the gene can be observed even in divergent crosses.

HALOTHANE‐GENOTYPE AND DURATION OF REFRIGERATED STORAGE EFFECTS ON THE QUALITY OF VACUUM‐PACKAGED PORK LOINS

ABSTRACTLoins (n=72) from halothane negative (NN) and carrier (Nn) pigs were vacuum‐packaged and stored for 0, 3, or 6 weeks at 2C. Samples from Nn pigs had more (P&lt;0.001) purge loss than NN‐loins after 3 and 6 weeks of storage. Color scores for chops of Nn pigs were lower (P&lt;0.001) than for the NN animals after 0 and 3 weeks; but after 6 weeks of storage, chops from Nn and NN pigs received similar American color scores. Chops from Nn pigs were lighter (P&lt;0.001) and less (P&lt;0.001) red than chops from the NN animals; however, L* values of chops from Nn pigs decreased, and a* values increased, from 0 to 3 weeks of storage. Although initial quality traits of chops from Nn pigs were inferior to those of NN, pork color of Nn‐pigs appeared to be improved with extended storage.

Effects of halothane genotype and pre-slaughter treatment on pig meat quality. Part 2. Physico-chemical traits of cured-cooked ham and sensory traits of cured-cooked and dry-cured hams

Forty-eight castrated F 2 offspring of Piétrain and Large White pigs were allocated to a 3×2 factorial design in order to study the interactive effect of halothane genotype (NN, Nn and nn) and pre-slaughter treatment (referred to as ’Experimental’ (EXP) and ’Commercial-like’ (COL) conditions; the latter involving short transportation, mixing unfamiliar pigs and slaughtering shortly after transport) on the qualities of cured-cooked and dry-cured hams. At 24 h post mortem, the hams were collected and assigned to cured-cooked (right ham) and dry-cured (left ham) ham processing. A sample of M. semimembranosus (SM) was collected before cooked ham processing, was used for chemical composition analysis, cured and then cooked at various temperatures. Cooking losses and compression tests were carried out after cooking on these SM samples. The water and collagen content of SM muscle was significantly higher in nn pigs compared with the two other genotypes. At all cooking temperatures (60, 65 and 70 °C), SM muscles from nn pigs showed higher cooking losses and instrumentally assessed toughness than the other genotypes, the heterozygous pigs being intermediate. The technological yield of cured-cooked ham processing was lower in nn, compared with NN and Nn animals. Cooked hams from nn pigs were drier, tougher, stringier and less smooth than NN and Nn pigs. The heterozygous pigs were similar to normal pigs for all texture characteristics with the exception of toughness for which they got a significantly higher score than NN pigs. The pigs slaughtered under the COL conditions had a better slice cohesiveness and a significantly lower dryness, than pigs slaughtered under the EXP conditions. The effect of HAL genotype on slice cohesiveness was significant only when pigs were slaughtered under the EXP conditions. Dry-cured hams from nn pigs showed significantly more visual defects, but were less tough, smoother and more fondant (softer) than NN and Nn pigs. The dry-cured hams from pigs slaughtered under the COL conditions had a better cohesiveness between muscles and a more intense yellow colour of fat than those from pigs slaughtered under the EXP conditions. COL pigs were also judged significantly less tough, smoother and more fondant than EXP ones. Overall, the effects of pre-slaughter treatment were small compared with those of the HAL genotype. The effects of HAL genotype on the sensory traits of cured-cooked ham were similar to those reported for fresh meat. However, the good textural characteristics of dry-cured ham processed from HAL positive pigs are somewhat surprising and need to be confirmed.

Efeito do gene do estresse suíno sobre características de quantidade e qualidade de carcaça

O gene do estresse suíno (gene hal), em homozigose recessiva (nn), está associado com a ocorrência da Síndrome do Estresse Porcino (PSS) e com a ocorrência da carne pálida, mole e exudativa (PSE). Em heterozigose (Nn), está relacionado com diminuição na qualidade da carne porém, com maior peso de carcaça. Neste estudo, foi caracterizado o genótipo do gene hal de 160 suínos por meio de análise do DNA extraído de um único folículo piloso. Estes animais foram abatidos e, após, mensuradas características de carcaça de cada um. Entre os 160 animais analisados, 82 (52,58%) foram caracterizados como NN, 67 (41,80%) como Nn e nove (5,62%) como nn. A variação das características de carcaça entre os genótipos foi avaliada por análise de variância, usando o SAS. Os animais dos três genótipos não diferiram quanto ao peso da carcaça quente, à espessura de toucinho, profundidade de músculo, porcentagem de carne magra e cor do músculo longissimus dorsi. Entretanto, a variação da cor ao longo da carcaça foi menor em animais NN (40,82%) do que em Nn (49,77%) e nn (53,83%). Estes resultados indicam que a presença do gene hal tanto em heterozigose como em homozigose recessiva não está associada ao maior peso de carcaça e a utilização destes animais pode acarretar em perda na qualidade da carne. Devido a isto, o uso intencional de animais homozigotos recessivos ou heterozigotos em programas de cruzamento deve ser desestimulado.

Effects of the MHS locus on growth, carcass and meat quality traits in F&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; crosses between Mangalitza and Piétrain breeds

Abstract. A total of 345 F2 animals from a crossbred design Mangalitza (homozygous NN) x Piétrain (homozygous nn) were fed ad libitum at the institute's Thalhausen Research Station and slaughtered at a live weight of approximately 100 kg. MHS genotypes (67 nn, 192 Nn and 86 NN) were determined directly in a DNA test targeting the ryanodine reeeptor locus. Models for analysis of variance included sire, dam, pen, slaughter group, sex and MHS effects. Growth Performance was generally lower and carcass composition minor compared to other breeds and crosses. No significant differences were found between MHS genotypes for growth traits but NN animals tended to be less eflicient with respect to food conversion. However, nearly all measurements of the carcass showed significant differences between nn and NN which were especially pronounced for sidefat thickness (−7 1mm) fat over the musculus longissimus dorsi (−8.8 mm) and loin eye area (+8.7 cm2) as well as fat area (−5.1 cm2) We found Nn animals performing similar to NN animals due to incomplete dominance of the N allele. As expected nn had a substantial negative influence on meat quality compared to NN and Nn (e.g. −0.61 and −0.15 for pH 45 min, respectively). Intramuscular fat content was at a high level and nn had significantly lower values with differences of −0.40% and −0.25% relative to NN and Nn, respectively. A whole genome scan is currently underway with emphasis on fat measurements which showed promising Variation in this study.

The effect of cyclopiazonic acid on the development of pale, soft, and exudative pork from pigs of defined malignant hyperthermia genotype.

Malignant hyperthermia (MH) and the mycotoxin cyclopiazonic acid (CPA) are each associated with abnormal calcium homeostasis in skeletal muscle, a key underlying factor in the development of pale, soft, and exudative (PSE) pork. To determine whether the natural presence of CPA in livestock feed ingredients contributes to the varying incidence of PSE in the pork industry, various levels of CPA (.1 to 50 mg/kg of diet) were included in the diets of market weight hogs (n = 52) of defined malignant hyperthermia genotype (NN = normal, Nn = a MH carrier, and nn = MH-positive). Animals with two copies of the MH mutation (nn) displayed improved live animal performance compared with NN and Nn animals (increased feed intake, average daily gain, and feed efficiency) but yielded lower quality loin chops as indicated by lower 45-min pH (P<.01), higher Commission Internationale de l'Eclairage (CIE) L* color coordinate values (P<.05), and higher drip losses (P<.01). The effects of CPA varied. In the first feeding trial, conducted under normal outside temperatures (2 degrees C), CPA had no effect (P> .2) on either live animal performance or meat quality. During the second trial, conducted under extreme outside temperatures (-18 degrees C), CPA-dependent reductions (P<.05) in feed intake, average daily gain, and 45-min pH in nn hogs support the possibility of interactions between malignant hyperthermia and dietary CPA on skeletal muscle calcium homeostasis and the development of PSE pork. These results suggest that this interaction may require stressful environmental conditions or the ingestion of CPA doses much higher than occur under natural conditions.

Altered calpain levels in longissimus muscle from normal pigs and heterozygotes with the ryanodine receptor mutation.

The calpain proteolytic system was examined in the longissimus muscle (LD) of heterozygote pigs carrying a single copy of a mutation in the skeletal muscle ryanodine receptor gene (RyR1) that is associated with porcine stress syndrome and reduced meat quality. Conventional British White-type pigs (n = 30) were selected from a commercial line on the basis of slaughter weight, backfat depth, and pH at 45 min postmortem > 6.0; based on DNA analysis, 11 were heterozygous RyR1 mutants (Nn), and 19 were normal genotype (NN). The LD samples were taken from carcasses at 2, 4, and 24 h postmortem for calpain analysis with enzyme assay and immunoblotting, using specific antisera raised against recombinant polypeptides derived from calpain large subunits and calpastatin. Shear force (SF) was measured after conditioning for 8 d at 2 degrees C and did not differ between Nn and NN groups. The extractable activity of mu-calpain decreased over 24 h postmortem (P < .001), with no significant difference in activity between NN and Nn animals at any time. The activity of m-calpain also decreased with time (P < .001), but it was lower at all times in Nn than in normal genotypes (P < .001). After Western blotting, the immunoreactivity of mu- and m-calpain large subunit bands declined over 24 h postmortem (P < .001); values for mu-calpain were higher (P < .05) and for m-calpain were lower (P < .001) in heterozygotes than in normal animals at each sampling time. The calpastatin antibody detected a major band of 135 kDa that declined with time postmortem but did not differ between Nn and NN genotypes at any sampling time. These data indicate that the levels of extractable mu- and m-calpain, but not calpastatin, may be different in pigs that carry the RyR1 mutation.

Effects of preslaughter management on the quality of carcasses from porcine stress syndrome heterozygous market hogs.

The objectives of this study were to determine whether two preslaughter management treatments, rest and mixing, influence the muscle quality of porcine stress syndrome (PSS) heterozygous (Nn) market hogs and to verify the expected quality characteristics of carcasses produced from PSS-normal (NN) and PSS-susceptible (nn) animals. Twenty-nine Nn, 14 NN, and 9 nn market hogs were randomly assigned to preslaughter handling treatments. One-half of the animals in each genotype group received 16 h of rest before slaughter, and the remaining pigs were slaughtered immediately upon arrival at the Iowa State University Meat Laboratory. Within each group, half of the Nn animals were mixed with unfamiliar pigs during transport and lairage. Length, backfat, and loin muscle area (LMA) were not affected by mixing and rest treatment. The carcasses from nn pigs had less fat (P < .05) measured at the 10th rib (off midline) and last lumbar vertebra (midline) and possessed larger LMA than carcasses from NN pigs. Heterozygous pigs were intermediate for most carcass traits. Carcass pH values among heterozygous groups were not significantly different, except that the rested animals had higher ultimate pH values (P < .01) and higher 45-min pH values. Resting had no effect on pH of NN or nn pigs. The 45-min pH values of nn carcasses were lower (P < .01) than those of NN carcasses, but ultimate pH values were similar. Values of unrested Nn animals were between those of NN and nn genotypes but with rest approached values of NN pigs. Loin muscle Minolta-Y and Hunter-L values from unrested Nn animals were higher ( P < .05) than those of rested Nn animals. Mixing did not influence these traits. The longissimus muscle lipid content was not influenced by treatment but differed among genotypes (P < .01). Glycogen levels of rested Nn animals tended to be lower than those of NN animals and approached those of nn pigs. Mixing of Nn animals resulted in higher (P < .05) chewiness scores of cooked loin chops. No significant cooking loss or InstronTM tenderness differences were observed between the PSS-Nn treatment groups. Even though 16 h of rest before slaughter improved the color and water-holding capacity of Nn pigs, effects were small and were much less than those that were due to the PSS gene.

Muscle glycogen level and meat quality in pigs of different halothane genotypes

The halothane genotype of 22 Polish landrace pigs was determined using halothane test and blood typing. Eight homozygous normal (NN), eight hetero-zygotes (Nn) and six homozygous recessive (nn) were identified. The levels of glycogen and lactate were measured in biopsy samples taken from the longissimus lumborum using a shot biopsy technique. pH (pH 1) and IMP/ATP ratio (R) were determined at 30 min after slaughter, while pH, meat colour and water holding capacity were determined on the day after slaughter. The halothane genotype did not affect intra vitam glycogen level. The nn pigs had a higher R value and lower pH 1 than both Nn and NN animals. Heterozygous animals were intermediate between both homo-zygotes for biopsy lactate level and meat colour. The lactate content of biopsy samples was significantly correlated with pH 1 ( r = −0·68; P < 0·01), R ( r = 0·68; P < 0·01), meat colour ( r = 0·57; P < 0·01) and water holding capacity ( r = 0·45; P · 0·05).

A within-litter comparison of the three halothane genotypes. 2. Performance, carcass quality, organ development and long-term effects of transportation and amperozide

The aim of the investigation was: (1) to compare the three Hal genotypes with respect to performance, carcass quality and organ development at slaughter, (2) to study long-lasting effects of transportation and treatment with amperozide. The study comprised 120 (23 NN, 69 Nn and 28 nn) crossbred pigs, offspring of heterozygous boars and sows. The Hal genotype was revealed by combining the halothane test and blood typing. At an average age of 12 weeks, the pigs were subjected to one of four treatments (with and without transport × with and without amperozide treatment). The pigs were kept in groups of four pigs ( 1 NN, 2 Nn and 1 nn) originating from different litters and were fed individually. Four nn pigs died during the experiment, one owing to fighting on the first day and three on the way to the slaughter house. The nn pigs had higher daily weight gain and lower feed to gain ratio than the NN and Nn animals. Carcass lean content was higher, but meat colour paler for the nn compared with the NN and Nn pigs. The heterozygotes were intermediate to the homozygotes for carcass lean content and meat colour. Organ weights were lower for the nn compared with the NN animals, and those of the Nn pigs were intermediate or close to the NN animals. Pigs subjected to a 5-h transport at 12 weeks had lower carcass lean content than non-transported ones. Amperozide treatment at the same age resulted in increased crude fat content of the liver at slaughter 3 months later. Adrenal weight at slaughter was higher for the amperozide-treated but nontransported animals compared with the other three treatment groups.

Effect of halothane genotype on muscle metabolism at slaughter and its relationship with meat quality: A within-litter comparison

The effects of halothane genotype on muscle metabolism at slaughter and its relationship with meat quality were studied within 16 litters. Heterozygous boars and sows were mated and the offspring were halothane tested and bloodtyped to reveal the halothane ( Hal) genotype of the 120 animals used ( NN, Nn or nn). Following slaughter at 100kg live weight, muscle samples from M. longissimus dorsi (LD) and M. quadriceps (Qu) were taken immediately after exsanguination and analysed for glycogen, glucose-6-phosphate, lactate, creatine phosphate (CP), and adenosine triphosphate (ATP), as well as for enzyme activities representing both the oxidative and glycolytic pathways. The enzyme activities were similar for all genotypes. All muscle metabolites differed significantly between samples from NN and nn animals, with higher lactate and glucose-6-phosphate and lower glycogen, CP and ATP in the nn muscles. The heterozygote animals were intermediate or close to either of the homozygotes. Meat quality characteristics (drip loss, surface and internal reflectance and dielectric loss factor) were studied only in the LD muscle. Meat quality of the muscle from the heterozygote ( Nn) animals was inferior to that from NN animals (no difference for internal reflectance) but better than that from nn animals. When reflectance and drip loss were combined into an index, very few values from the nn-animals were better than the total mean. Indexes from the dominant homozygotes were generally better than the mean and those of heterozygotes were approximately normally distributed around the mean.

Effects of transport stress on concentrations of cortisol, corticosteroid-binding globulin and glucocorticoid receptors in pigs with different halothane genotypes.

Effects of stress on concentrations of cortisol and corticosteroid-binding globulin (CBG) in blood plasma and on glucocorticoid receptor concentrations in muscle cytosol were studied in pigs representing three Halothane (Hal) genotypes (NN, Nn, nn). At 12 wk of age, animals were divided into four groups: pigs subjected to transport (5 h in a truck), pigs treated with amperozide prior to transport, pigs not transported but treated with amperozide and pigs neither transported nor given amperozide. Animals were slaughtered the week they reached 100 kg live weight (3 mo later). The Hal gene showed no major influence on the variables studied except for cortisol concentrations (P = .06) measured directly after transport at 12 wk of age (NN = 66.8 nM, Nn = 61.4 nM, nn = 69.4 nM). However, the response in each Hal genotype differed, depending on whether or not the pigs had been exposed to transport. Two weeks after transport, NN pigs developed higher cortisol concentrations than untransported animals, whereas the response was reversed in nn animals; Nn pigs showed no difference in this regard. At slaughter, the effect of transport (12 wk of age) on cortisol and CBG was still apparent. In NN pigs cortisol and CBG concentrations were elevated (P less than or equal to .05, P = .08, respectively), whereas concentrations tended to be lower in nn pigs (P = .17, P = .07, respectively) when compared with untransported pigs. Transported pigs had lower receptor concentrations at slaughter (P less than or equal to .01) than untransported pigs. However, pigs given amperozide in connection with transport had a receptor concentration comparable to that in untransported pigs. Our study shows conclusively that transport stress had long-term effects on cortisol, CBG and glucocorticoid receptor concentrations. In addition, amperozide had long-term effects on cortisol and receptor concentrations.

Retinotectal map formation in dually innervated tecta: a regeneration study in Xenopus with one compound eye following bilateral optic nerve section.

Retinotectal map formation was studied during regeneration in young adult Xenopus. Right compound double-temporal eyes (TT) were formed in tailbud stage embryos by the fusion of two temporal halves of the eye blastema in the same orbit. In other animals right compound double-nasal eyes (NN) were prepared. In both combinations the left eye was kept intact. After metamorphosis the right and left optic nerves were sectioned to induce optic fiber regeneration from each eye to both tecta. The patterns of retinotectal projections from the compound and normal eyes were studied from 37 to 364 days after optic nerve section, using electrophysiological recording of the visuotectal projections and 3H-proline autoradiographic assay from one of the two eyes. The left normal eyes projected in a retinotopic fashion, across the entire extent of the right and left dually innervated tecta. In contrast, the right compound eye projections were confined to the rostrolateral or to the caudomedial part of the right and left tecta and TT and NN animals, respectively. These tectal areas corresponded to the termination of temporal and nasal hemiretinal fibers of the normal eye. Discontinuous, interdigitating projection patterns from the right and left eyes were found in parts of the tecta where the compound and the normal eye projections overlapped. These results indicate that the normal optic fiber projections caused the originally expanded compound eye projections to be restricted to the corresponding part of the dually innervated tecta. It is suggested that the orderliness and the extent of the retinotectal map are established by the competition and interaction of optic fibers based on stable positional programming of the retinal ganglion cells.

Quantitative Comparisons of Acidic Prealbumin (Pr) Phenotypes in Horses

Comparisons of Pr protein amounts in horse sera have been performed using Mancini et al.’s (1965) immunodiffusion technique. Relative values against a chosen standard of 100 % were determined for a total of 435 horses. There was considerable variation between horses, the highest Pr value being 125 % and the lowest 50 % of the standard. In animals of the same Pr phenotype the mean Pr values were significantly higher (P < 0.001) in foals than in mares. In Norwegian Trotter horses the Pr value of Pr NN animals was significantly higher than that of Pr SS phenotypes, whereas the mean Pr values of Pr SS was significantly higher than that of Pr UU Warmblood Trotter horses, the Pr value of Pr SS being 90 % and the Pr-UU 80 % of that of Pr NN. No difference between sexes with regard to Pr values was found.