F. Gil

A comparison of carcass, meat quality and histochemical characteristics of Iberian (Guadyerbas line) and Landrace pigs

Carcass, meat quality and histochemical traits were studied in 20 Landrace (LR) pigs from a maternal line and 12 Iberian pigs (IB) from the Guadyerbas line, including boars and gilts. The animals were reared under commercial intensive management and fed ad libitum from 27 kg liveweight (12 weeks of age) to 100 kg for LR, while IB pigs were 6 weeks older in order to reach the tentative 100 kg slaughter weight at the same time. Actual LR and IB slaughter weights were 105±10 and 118±11 kg, respectively. Iberian pigs had higher killing out percentage (78.6 vs. 72.4, P<0.001) and backfat depth (48.1 vs. 20.7 mm, P<0.001) than LR pigs. Higher pH 24 h post-mortem were observed in m. longissimus lumborum and m. semimembranosus muscles of IB than of LR breeds. Also, IB breed had higher haem pigment contents than LR. Iberian pigs showed higher intramuscular fat percentage (3.91 vs. 0.66 in longissimus, P<0.001), more saturated and monounsaturated backfat and lower concentrations of C18:2 and C18:3 than LR pigs. Muscle showed a more oxidative metabolism in IB than in LR pigs. The proportion of type I fibres was higher (12.09 vs. 9.09%, P<0.001) and their diameter was larger (44.37 vs. 40.83 μm, P<0.05) in IB than in LR pigs, whereas the opposite occurred for type 2B fibres proportion and diameter. The percentage of intramuscular fat in IB pigs was positively correlated (P<0.05) with the proportion of type I fibres.

Temperature effects on muscle growth in two populations (Atlantic and Mediterranean) of sea bass, Dicentrarchus labrax L.

Two genetically different populations of sea bass, Dicentrarchus labrax L., Atlantic (Atl.) and Mediterranean (Med.), were subjected to the following incubation/cultivation temperatures (T): 15 °C/natural, 17 °C/natural, 15/19 °C, 17/19 °C (natural T averaging 15 °C and raising gradually). Muscle cellularity was measured at different larval stages for each T regime. During the vitelline phase, muscle growth was mainly due to muscle fibre hypertrophy. In Med. larvae, higher incubation T (17 °C) increased the area of white and red fibres at hatching, while in Atl. larvae there was no significant T effect at this stage. At mouth opening, the area of white fibres increased at 19 °C in Atl. larvae (P<0.05), but in Med. larvae it was similar for all temperatures. Following yolk-sac reabsorption, hypertrophy and hyperplasia increased in both populations. In these stages (20–55 days), both parameters were greater at 19 °C (P<0.05). Metamorphosis finished earlier at 19 °C. At this stage, Atl. larvae reared at 19 °C showed higher value of total myotomal area than at natural T, while in Med. sea bass, larvae reared at 19 °C showed a lower size of the myotome than at 17 °C/natural. In larvae from both populations reared at natural T, incubating T had a positive effect at the end of metamorphosis, thus the total myotomal area were higher at 17 °C/natural than at 15 °C/natural. Following metamorphosis, all groups showed a rapid growth, but higher at 19 °C (P<0.05). The results indicate that muscle cellularity was clearly influenced by T, and that both populations had different levels of response. These differences can be apparently associated with their respective genetic background.

Early temperature effects on muscle growth dynamics and histochemical profile of muscle fibres of sea bass Dicentrarchus labrax L., during larval and juvenile stages

Recently, it has been found that the thermal experience during the earliest phases of development could determine the larval and postlarval growth characteristics of teleosts. In order to investigate the effects of the early temperature regime on the advanced stages of growth of sea bass, Dicentrarchus labrax L., this species was reared during the vitelline phase at two temperatures: natural temperature (i15 jC) and 17.7F0.1 jC, and then larvae transferred to common temperature (natural temperature). Muscle growth was studied by morphometric and histochemical techniques (mATPase and NADH-TR). Body length and body mass were also measured. During the vitelline phase, muscle growth was similar in both experimental groups, but at 25 days, both hypertrophy and hyperplasia of white muscle fibres were greater in the prewarmed group (p<0.05). At the end of metamorphosis (80 days) and at 120 days, the average diameter of white muscle fibres, as well as the body length, were greater in the prewarmed group (p<0.05), but the number of white fibres did not differ significantly between groups. The morphological mosaic of white muscle fibres was observed at the end of metamorphosis, and the histochemical mosaic appeared gradually since the early postlarval stages. Thus, at 120 days, some specimens in both experimental groups showed three or four different mATPase staining white fibres: low (L), moderate (M), high (H) and/or very high (vH), whereas in other specimens, only L or M mATPase activity fibres were observed. Early T influenced the histochemical maturity of the

Ultrasound-guided block of the sciatic and femoral nerves in dogs: a descriptive study.

Ten canine cadavers were used to investigate the anatomy and ultrasonographic approaches to the sciatic (ScN) and femoral (FN) nerves and to assess the accuracy of an ultrasound (US) guided technique to locate and block these nerves in the dog. The nerves of four sedated dogs were sought using US, blocked with 1% lidocaine and successful location confirmed by peripheral neurostimulation. The ScN was identified by US in all cases whereas the FN was not located in all cases. This study validates the usefulness of the US-guided technique to locate and block the ScN at the midfemoral level but the acoustic window of the inguinal region was less successful for locating and blocking the FN.

Temperature effect on muscle growth of the axial musculature of the sea bass (Dicentrarchus labrax L.)

In order to determine the temperature effect on the axial muscle growth of sea bass, a stock of larvae was subjected to the following incubation and cultivation temperatures, respectively: 15°C/ambient, 15/17°C, 17°C/ambient and 17/17°C. In all groups the cross‐sectional area of white and red muscles and the number and average area of the white and red muscle fibres were quantified. Results showed that the embryonic period, pre‐larval phase and the end of metamorphosis were accelerated at higher temperatures. During the endogenous feeding period, muscle growth took place by fibrillar hypertrophy, and was not influenced by the temperature. Thereafter (external feeding) muscular hyperplasia began, and growth of all the muscular parameters was favoured by the effect of high incubation and cultivation temperatures, with the latter having higher influence. High incubation temperature had an slight effect on muscle growth and body length, which was only observed from 15 days. Metamorphosis finished at 3 ± 0.4 cm in all the larvae, but this length was earlier reached at higher temperatures. At 120 days, the largest growth was obtained in the larvae maintained at a higher temperature.

Anatomy of the equine temporomandibular joint: study by gross dissection, vascular injection and section.

REASONS FOR PERFORMING STUDY The minute anatomy of the temporomandibular joint (TMJ) in horses is poorly documented in the literature. OBJECTIVES To examine in detail the anatomy of the normal equine TMJ and the relationship of the joint to adjacent structures. METHODS The anatomy of the TMJ was examined in 12 equidae using dissections, synovial and vascular injections and frozen and plastinated sections. Relevant structures were photographed. RESULTS Rostral and caudal compartments were identified in the dorsal and ventral synovial pouches of the TMJ. Lateral and caudal ligaments were identified and attachments of the masticatory muscles over the TMJ were documented. Direct relationships between the TMJ and components of the ear were found, and the vascular supply described. CONCLUSIONS This joint is related to some components of the ear as in man, and has its own peripheral vascular supply. POTENTIAL RELEVANCE A knowledge of the detailed anatomy of the equine TMJ is a prerequisite to interpreting the imaging techniques, and will enable improved diagnosis of TMJ pathologies.

A quantitative trait locus genome scan for porcine muscle fiber traits reveals overdominance and epistasis

Muscle histochemical characteristics are decisive determinants of meat quality. The relative percentage and diameters of the different muscular fiber types influence crucial aspects of meat such as color, tenderness, and ultimate pH. Despite its relevance, however, the information on muscle fiber genetic architecture is scant, because histochemical muscle characterization is a laborious task. Here we report a complete QTL scan of muscle fiber traits in 160 animals from a F(2) cross between Iberian and Landrace pigs using 139 markers. We identified 20 genome regions distributed along 15 porcine chromosomes (SSC1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, and X) with direct and(or) epistatic effects. Epistasis was frequent and some interactions were highly significant. Chromosomes 10 and 11 seemed to behave as hubs; they harbored 2 individual QTL, but also 6 epistatic regions. Numerous individual QTL effects had cryptic alleles, with opposite effects to phenotypic pure breed differences. Many of the QTL identified here coincided with previous reports for these traits in the literature, and there was overlapping with potential candidate genes and previously reported meat quality QTL.

Muscle Development in Gilthead Sea Bream (Sparus aurata, L.) and Sea Bass (Dicentrarchus labrax, L.): Further Histochemical and Ultrastructural Aspects

The histochemical profiles ‐ mATPase and NADH‐TR reactions ‐ of the red and white muscle fibres of gilthead sea bream and sea bass were determined from the first week after hatching. Modifications of the mATPase technique by combinations of pH/time/molarity were carried out in order to compare the sensitivity of the myosin ATPase of each muscle fibre type of the lateral muscle. Results showed that the staining of muscle fibres was independent of small modifications in the technique. The intermediate ‘pink’ muscle was histochemically defined towards the end of the larval life and is considered to be implicated in the growth of the myotome. A layer of external cells was observed, by electron microscopical examination, between the connective tissue of the skin and the superficial red muscle fibres of larvae and postlarvae. It is suggested that the external cells are unlikely to be a source of red muscle fibres and implicated on the growth of the myotome, but rather a part of the dermatome. The timing, areas and mechanisms of hyperplastic growth of the myotome were defined and discussed.

Histochemical Skeletal Muscle Fibre Types in the Sheep

In this study, the differentiation of adult and postnatal muscle fibres in sheep longissimus thoracis muscle has been characterized. By using a variety of histochemical methods, we have investigated the m‐ATPase and metabolic activities of skeletal muscle fibres in adult sheep and lambs aged between 1 day and 3 months. Types I, IIA, IIB and IIC fibres were identified. The results showed that the interpretation of the fibre type composition depends on the methods used. The findings also revealed that the fibre types IIA and IIB can be separated histochemically in sheep by using the correct m‐ATPase technique, even at early stages of postnatal development, and that the origin of the four different fibres of the adult can be traced back to early postnatal stages.

Ventral ultrasound-guided suprainguinal approach to block the femoral nerve in the dog.

This prospective study assessed a ventral ultrasound-guided suprainguinal approach to block the femoral nerve (FN) in dogs. The anatomical features of the FN were evaluated in four canine cadavers. In another five cadavers, the FN was located by ultrasound-guidance and the accuracy of this technique was evaluated by injection of black ink and posterior evaluation of the degree of staining of the nerves. In five live dogs, the FN was blocked with 2% lidocaine. The distribution of lidocaine around the nerve and the presence of motor deficit were evaluated. The FN was easily located and accurately blocked in all cases. This new ultrasound-guided approach was reliable for blocking the FN and might be a suitable alternative to the traditional approaches described to block the FN in the dog.