Growth performance of South African Windsnyer pigs to the dietary inclusion of Amarula oil cake.

Dietary inclusion of Amarula oil cake (AOC) in pig diets can ease pressure of relying on non-native feed sources and benefit the swine industry. The study was conducted to determine the growth performance of Windsnyer pigs fed increasing levels of AOC. Twenty-five clinically growing male boars with an initial body weight of 19.92 ± 8.74 kg were used in the study that lasted 6 weeks. All pigs were allocated to diets in a completely randomised design. Five experimental diets were formulated to contain 0, 50, 100, 150 and 200 g/kg DM of AOC. Average daily feed intake (ADFI), average daily gain (ADG), feed conversion ratio (FCR), scaled average daily feed intake (SADFI), scaled average daily gain (SADG) and body weight (BW) were calculated weekly. The diet affected ADFI, ADG, FCR and SADG (P < 0.05). Scaled average daily feed intake was not affected by the diet (P > 0.05). There was a significant interaction between AOC inclusion and weeks of feeding on ADFI, ADG and FCR (P < 0.05). Age of pigs decreased FCR quadratically (P < 0.001). A quadratic relationship between ADFI and increasing levels of AOC was observed (P < 0.05). Average daily gain, FCR and SADG decreased linearly with increasing AOC levels (P < 0.05). Using the broken stick analyses, the maximum inclusion of AOC was 102.17 g/kg DM. Amarula oil cake can be incorporated in diets of Windsnyer pigs up to 100 g/kg DM without constraining growth performance.

In vitro digestibility of four high moisture grains used in liquid pig feeding.

One of the main challenges in the livestock sector is the need to increase sustainability and production efficiency. In pig production, feed is the main production cost. High moisture grains (HMGs) have recently emerged as an interesting alternative to conventional feedstuffs. In this study, the nutritional value for pigs of eight HMGs was determined considering the chemical composition and the in vitro digestibility. We have used four seeds (lupine, barley, wheat, and corn) and two substrates (water and whey). Lupine HMG showed higher values of crude fat (2.12%) and crude protein (8.59%). Within cereal HMGs, corn HMG showed higher DM (34.37%), OM (36.27%), and starch (27.17%) values; wheat HMG stood out for crude protein content (4.23%) and barley for NDF (5.68%). The pH values were low for all HMG, with lupine having the highest value (4.39). Ammoniacal nitrogen had the highest value for wheat HMG (6.10%). When whey was used as substrate, it improved the characteristics of the HMG. Regarding in vitro digestibility, of the four HMGs studied, wheat showed the highest value for DM (89.93%), while lupine showed the highest value for crude protein (96.12%). When considering the substrates, whey showed better results for all in vitro digestibility's parameters (87.48%, 90.95%, and 90.59%, for DM, OM, and crude protein, respectively). Overall, all HMGs showed good conservation of nutritional value and high in vitro digestibility. The use of whey as a substrate was beneficial for HMG quality. Results show that the analyzed HMG can be efficiently used in the framework of swine production.

Deciphering the role of ttrA and pduA genes for Salmonella enterica serovars in a chicken infection model.

Salmonella enterica serovars use self-induced intestinal inflammation to increase electron acceptor availability and to obtain a growth advantage in the host gut. There is evidence suggesting that the ability of Salmonella to use tetrathionate and 1,2-propanediol provides an advantage in murine infection. Thus, we present here the first study to evaluate both systemic infection and faecal excretion in commercial poultry challenged by Salmonella Enteritidis (SE) and S. Typhimurium (STM) harbouring deletions in ttrA and pduA genes, which are crucial to the metabolism of tetrathionate and 1,2-propanediol, respectively. Mutant strains were excreted at higher rates when compared to the wild-type strains. The highest rates were observed with white egg-layer and brown egg-layer chicks (67.5%), and broiler chicks (56.7%) challenged by SEΔttrAΔpduA, and brown egg-layer chicks (64.8%) challenged by STMΔttrAΔpduA. SEΔttrAΔpduA presented higher bacterial counts in the liver and spleen of the three chicken lineages and caecal contents from the broiler chickens, whereas STMΔttrAΔpduA presented higher counts in the liver and spleen of the broiler and brown-egg chickens for 28 days post-infection (P < 0.05). The ttrA and pduA genes do not appear to be major virulence determinants in faecal excretion or invasiveness for SE and STM in chickens. RESEARCH HIGHLIGHTSttrA and pudA do not impair gut colonization or systemic infection in chicks.Mutant strains were present in higher numbers in broilers than in laying chicks.Mutants of SE and STM showed greater pathogenicity in broiler chicks than layers.

Assessing mineral status in edible tissues of domestic and game animals: a review with a special emphasis in tropical regions.

Mineral status in edible tissues has been extensively studied since the beginning of the twentieth century. Most research focus on nutrition, as the earliest reports were essentially related to nutrition, animal health and mineral deficiencies. Nutrition wise, minerals are of great importance for consumers worldwide, as meat (i.e. beef, pork, chicken) and fish are major sources of protein in human diets. Nutrition gains renewed importance in the tropical context, since tropical forages are poor in minerals. This fact contributes to mineral deficiencies and impaired production performance in extensive production systems, with greater emphasis in ruminant species. In addition to nutrition, several other factors have an important impact in mineral metabolism such as geographic location, gender and species. In this article, we aim to infer on both the role in the organism and the amount present in various edible tissues of different species, either game or production animals, presenting an overall perspective in the context of tropical animal production.

Phylogeny and variability of Colletotrichum truncatum associated with soybean anthracnose in Brazil.

AIMS: Fungal diseases are among the main factors limiting high yields of soybean crop. Colletotrichum isolates from soybean plants with anthracnose symptoms were studied from different regions and time periods in Brazil using molecular, morphological and pathogenic analyses. METHODS AND RESULTS: Bayesian phylogenetic inference of GAPDH, HIS3 and ITS-5.8S rDNA sequences, the morphologies of colony and conidia, and inoculation tests on seeds and seedlings were performed. All isolates clustered only with Colletotrichum truncatum species in three well-separated clusters. Intraspecific genetic diversity revealed 27 distinct haplotypes in 51 fungal isolates; some of which were identical to C. truncatum sequences from other regions around the world, while others were related to alternative hosts. Conidia were falcate, hyaline, unicellular and aseptate, formed in acervuli, with variable dimensions. Despite being pathogenic to seedlings by both inoculation methods, variation was observed in the aggressiveness of the tested isolates, which was not correlated with genetic variation. CONCLUSION: The identification of C. truncatum in the sampled isolates was evidenced as being the only causal agent of soybean anthracnose in Brazil until 2007, with relevant genetic, morphological and pathogenic variability as well as a broad geographical origin. The wide distribution of the predominant C. truncatum haplotype indicated the existence of a highly efficient mechanism of pathogen dispersal over long distances, reinforcing the role of seeds as the primary source of disease inoculum. SIGNIFICANCE AND IMPACT OF THE STUDY: The characterization and distribution of Colletotrichum species in soybean-producing regions in Brazil is fundamental for understanding the disease epidemiology and for ensuring effective control strategies against anthracnose.

Complete genome sequence of bean rugose mosaic virus, genus Comovirus.

Since the first report in Costa Rica in 1971, bean rugose mosaic virus (BRMV) has been found in Colombia, El Salvador, Guatemala and Brazil. In this study, the complete genome sequence of a soybean isolate of BRMV from Paraná State, Brazil, was determined. The BRMV genome consists of two polyadenylated RNAs. RNA1 is 5909 nucleotides long and encodes a single polypeptide of 1856 amino acids (aa), with an estimated molecular weight of 210 kDa. The RNA1 polyprotein contains the polypeptides for viral replication and proteolytic processing. RNA2 is 3644 nucleotides long and codes for a single polypeptide of 1097 aa, containing the movement and coat proteins. This is the first complete genome sequence of BRMV. When compared with available aa sequences of comoviruses, the highest identities of BRMV coat proteins and proteinase polymerase were 57.5 and 58 %, respectively. These were below the 75 and 80 % identity limits, respectively, established for species demarcation in the genus. This confirms that BRMV is a member of a distinct species in the genus Comovirus.

Viability of Yersinia pestis subcultures in agar stabs.

UNLABELLED: Since its identification as the causative agent of plague in 1894, thousands of Yersinia pestis strains have been isolated and stored. Here, we report the ability of Y. pestis to survive up to 47 years in agar stabs, in rubber-stoppered tubes, under refrigeration (+4 to +10°C), although overall subculture recovery rates were poor and inversely related to the length of time stored. Genetic characterization of virulence gene presence among these subcultures was suggestive of significant variation in the genomic stability of Y. pestis subcultures stored under these conditions. Specifically, we found variation in the presence of plasmid and chromosomal virulence markers (genes pla, lcrV, caf1 and irp2) among multiple subcultures of Y. pestis strains in the 'Collection of Yersinia pestis' (Fiocruz-CYP) maintained by the SRP of FIOCRUZ-PE in Brazil. This variation, together with all of the inherent temporal, geographic and other genetic variation represented by all of the recoverable strains in this historical collection was preserved in new frozen culture stocks stored at -70°C as a result of this study. These frozen culture stocks represent a valuable resource for future comparative studies of Y. pestis. SIGNIFICANCE AND IMPACT OF THE STUDY: We report the ability of Yersinia pestis to survive up to 47 years in agar stabs, in rubber-stoppered tubes, under refrigeration (+4 to +10°C), although overall subculture recovery rates were poor and inversely related to the length of time stored. Genetic characterization of virulence gene presence among these subcultures was suggestive of significant variation in the genomic stability of Y. pestis subcultures stored under these conditions. This variation, together with all of the inherent temporal, geographic and other genetic variation represented by all of the recoverable strains in the historical 'Collection of Yersinia pestis' (Fiocruz-CYP) maintained by the SRP of FIOCRUZ-PE in Brazil was preserved in new frozen culture stocks stored at -70°C as a result of this study. These frozen culture stocks represent a valuable resource for future comparative studies of Y. pestis.

Molecular variability of cowpea mild mottle virus infecting soybean in Brazil.

Molecular variability was assessed for 18 isolates of cowpea mild mottle virus (CPMMV, genus Carlavirus, family Betaflexiviridae) found infecting soybean in various Brazilian states (Bahia, Goiás, Maranhão, Mato Grosso, Minas Gerais, Pará) in 2001 and 2010. A variety of symptoms was expressed in soybean cv. CD206, ranging from mild (crinkle/blistering leaves, mosaic and vein clearing) to severe (bud blight, dwarfing, leaf and stem necrosis). Recombination analysis revealed only one CPMMV isolate to be recombinant. Pairwise comparisons and phylogenetic analysis were performed for partial genomes (ORF 2 to the 3' terminus) and for each ORF individually (ORFs 2 to 6), showing the isolates to be distinct. The topology of the phylogenetic tree could be related to symptoms, but not to the year of collection or geographical origin. Additionally, the phylogenetic analysis supported the existence of two distinct strains of the virus, designated CPMMV-BR1 and CPMMV-BR2, with molecular variations between them.

In vitro characterization of Trichophyton rubrum and T. mentagrophytes biofilms.

Dermatophytes are fungi responsible for a disease known as dermatophytosis. Biofilms are sessile microbial communities surrounded by extracellular polymeric substances (EPS) with increased resistance to antimicrobial agents and host defenses. This paper describes, for the first time, the characteristics of Trichophyton rubrum and T. mentagrophytes biofilms. Biofilm formation was analyzed by light microscopy, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) as well as by staining with crystal violet and safranin. Metabolic activity was determined using the XTT reduction assay. Both species were able to form mature biofilms in 72 h. T. rubrum biofilm produced more biomass and EPS and was denser than T. mentagrophytes biofilm. The SEM results demonstrated a coordinated network of hyphae in all directions, embedded within EPS in some areas. Research and characterization of biofilms formed by dermatophytes may contribute to the search of new drugs for the treatment of these mycoses and might inform future revisions with respect to the dose and duration of treatment of currently available antifungals.

Phylogeny and micro-habitats utilized by lizards determine the composition of their endoparasites in the semiarid Caatinga of Northeast Brazil.

Trophic networks can have architectonic configurations influenced by historical and ecological factors. The objective of this study was to analyze the architecture of networks between lizards, their endoparasites, diet, and micro-habitat, aiming to understand which factors exert an influence on the composition of the species of parasites. All networks showed a compartmentalized pattern. There was a positive relation between diet and the diversity of endoparasites. Our analyses also demonstrated that phylogeny and the use of micro-habitat influenced the composition of species of endoparasites and diet pattern of lizards. The principal factor that explained the modularity of the network was the foraging strategy, with segregation between the "active foragers" and "sit-and-wait" lizards. Our analyses also demonstrated that historical (phylogeny) and ecological factors (use of micro-habitat by the lizards) influenced the composition of parasite communities. These results corroborate other studies with ectoparasites, which indicate phylogeny and micro-habitat as determinants in the composition of parasitic fauna. The influence of phylogeny can be the result of coevolution between parasites and lizards in the Caatinga, and the influence of micro-habitat should be a result of adaptations of species of parasites to occupy the same categories of micro-habitats as hosts, thus favoring contagion.

Isochronous island bifurcations driven by resonant magnetic perturbations in tokamaks.

Recent evidence shows that heteroclinic bifurcations in magnetic islands may be caused by the amplitude variation of resonant magnetic perturbations in tokamaks. To investigate the onset of these bifurcations, we consider a large aspect ratio tokamak with an ergodic limiter composed of two pairs of rings that create external primary perturbations with two sets of wave numbers. An individual pair produces hyperbolic and elliptic periodic points, and its associated islands, that are consistent with the Poincaré-Birkhoff fixed-point theorem. However, for two pairs producing external perturbations resonant on the same rational surface, we show that different configurations of isochronous island chains may appear on phase space according to the amplitude of the electric currents in each pair of the ergodic limiter. When one of the electric currents increases, isochronous bifurcations take place and new islands are created with the same winding number as the preceding islands. We present examples of bifurcation sequences displaying (a) direct transitions from the island chain configuration generated by one of the pairs to the configuration produced by the other pair, and (b) transitions with intermediate configurations produced by the limiter pairs coupling. Furthermore, we identify shearless bifurcations inside some isochronous islands, originating nonmonotonic local winding number profiles with associated shearless invariant curves.

Impact of dietary Laminaria digitata with alginate lyase or carbohydrase mixture on nutrient digestibility and gut health of weaned piglets.

Laminaria digitata is a brown seaweed rich in prebiotic polysaccharides, mainly laminarin, but its alginate-rich cell wall could compromise nutrient access. Carbohydrase supplementation, such as individual alginate lyase and carbohydrases mixture (Rovabio® Excel AP), could enhance nutrient digestibility and prebiotic potential. This study aimed to evaluate the effect of these enzymes on nutrient digestibility and gut health of weaned piglets fed with 10% L. digitata. Diets did not affect growth performance (P > 0.05). The majority of the feed fractions had similar digestibility across all diets, but the supplementation of alginate lyase increased hemicellulose digestibility by 3.3% compared to the control group (P = 0.047). Additionally, we observed that algal zinc was more readily available compared to the control group, even without enzymatic supplementation (P < 0.001). However, the increased digestibility of some minerals, such as potassium, raises concerns about potential mineral imbalance. Seaweed groups had a higher abundance of beneficial bacteria in colon contents, such as Prevotella, Oscillospira and Catenisphaera. Furthermore, the addition of alginate lyase led to a lower pH in the colon (P < 0.001) and caecum (P < 0.001) of piglets, which is possibly a result of released fermentable laminarin, and is consistent with the higher proportion of butyric acid found in these intestinal compartments. L. digitata is a putative supplement to enhance piglet gut health due to its prebiotic polysaccharides. Alginate lyase supplementation further improves nutrient digestibility and prebiotic potential. These results suggest the potential use of L. digitata and these enzymatic supplements in commercial piglet-feeding practices.

Microplate alamarBlue assay for Paracoccidioides susceptibility testing.

CLSI method M27-A3 is not available for use with dimorphic fungi, such as those of the Paracoccidioides genus. In this study, we developed a microdilution method and added the alamarBlue reagent to test the responses of Paracoccidioides brasiliensis and Paracoccidioides lutzii against amphotericin B and itraconazole antifungals. The test proved to be sensitive, practical, and inexpensive and can be used to monitor the activity of low-growth microorganisms and their response to various drugs.

Cryptococcosis: epidemiology, fungal resistance, and new alternatives for treatment.

Cryptococcosis is an important systemic mycosis and the third most prevalent disease in human immunodeficiency virus (HIV)-positive individuals. The incidence of cryptococcosis is high among the 25 million people with HIV/acquired immunodeficiency syndrome (AIDS), with recent estimates indicating that there are one million cases of cryptococcal meningitis globally per year in AIDS patients. In Cryptococcus neoformans, resistance to azoles may be associated with alterations in the target enzyme encoded by the gene ERG11, lanosterol 14α-demethylase. These alterations are obtained through mutations, or by overexpressing the gene encoding. In addition, C. gattii and C. neoformans present a heteroresistance phenotype, which may be related to increased virulence. Other species beyond C. neoformans and C. gattii, such as C. laurentii, have been diagnosed mainly in patients with immunosuppression. Infections of C. albidus have been isolated in cats and marine mammals. Recent evidence suggests that the majority of infections produced by this pathogen are associated with biofilm growth, which is also related with increased resistance to antifungal agents. Therefore, there is a great need to search for alternative antifungal agents for these fungi. The search for new molecules is currently occurring from nanoparticle drugs of plant peptide origin. This article presents a brief review of the literature regarding the epidemiology of cryptococcosis, as well as fungal resistance and new alternatives for treatment.

Subtyping Brazilian Yersinia pestis strains by pulsed-field gel electrophoresis.

We subtyped Brazilian Yersinia pestis strains by pulsed-field gel electrophoresis (PFGE). This was done with 22 Brazilian Y. pestis strains: 17 from an outbreak and 5 from endemic routine surveillance. The strains were divided into 2 groups (I and II), 8 subgroups (A-H) and 19 PFGE profiles or pulsotypes. PFGE did not separate outbreak from non-outbreak strains, as identical pulsotype patterns were found among outbreak strains and strains obtained from surveillance. However, it was able to detect intraspecific genetic diversity among Brazilian strains. This PFGE technique was able to differentiate a homogeneous group of Brazilian Y. pestis strains.

Adhesion of Histoplasma capsulatum to pneumocytes and biofilm formation on an abiotic surface.

The pathogenic fungus, Histoplasma capsulatum, causes the respiratory and systemic disease 'histoplasmosis'. This disease is primarily acquired via inhalation of aerosolized microconidia or hyphal fragments of H. capsulatum. Evolution of this respiratory disease depends on the ability of H. capsulatum yeasts to survive and replicate within alveolar macrophages. It is known that adhesion to host cells is the first step in colonization and biofilm formation. Some microorganisms become attached to biological and non-biological surfaces due to the formation of biofilms. Based on the importance of biofilms and their persistence on host tissues and cell surfaces, the present study was designed to investigate biofilm formation by H. capsulatum yeasts, as well as their ability to adhere to pneumocyte cells. H. capsulatum biofilm assays were performed in vitro using two different clinical strains of the fungus and biofilms were characterized using scanning electron microscopy. The biofilms were measured using a 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium-hydroxide (XTT) reduction assay. The results showed that both the H. capsulatum strains tested were very efficient at adhering to host cells and forming biofilm. Therefore, this is a possible survival strategy adopted by this fungus.

Genetic diversity of Yersinia pestis in Brazil.

Plague outbreaks are occasionally reported in Brazil. Unfortunately, due to great genetic similarity, molecular subtyping of Yersinia pestis strains is difficult. Analysis of multiple-locus variable number of tandem repeats (VNTR), also known as MLVA, has been found to be a valuable tool to discriminate among strains. To check for genetic differences, strains obtained from two different ecological complexes in Brazil collected during two different epidemiological events, an epizootic in Sítio Alagoinha in 1967 and an outbreak in Planalto da Borborema in 1986, were subtyped through MLVA using 12 VNTR loci. Three clusters (A, B and C) were observed. Of the 20 strains from the epizootic, 18 fit into cluster A. Cluster A was divided into two subgroups: A(1) (15 strains) and A(2) (3 strains). Of the 17 strains from the outbreak, 15 fit into cluster B. Cluster B was divided into three subgroups: B(1) (4 strains), B(2) (4 strains) and B(3) (7 strains). Cluster C is a singleton with one epizootic strain. The external standards, Y. pestis CO92 and Y. pseudotuberculosis IP32953, formed two clusters of singletons. The stability of 12 VNTR loci of three unrelated cultures included in this study was assessed. The 12 VNTR loci were stable through multiple serial subcultures in the laboratory. MLVA revealed that Y. pestis populations in Brazil are not monomorphic, and that there is intraspecific genetic diversity among Brazilian plague strains. We conclude that there is some correlation among genetic groups of this species, related to the temporal and geographic origin of isolates.

Patterned separator membranes with pillar surface microstructures for improved battery performance.

In order to improve battery performance by tuning battery separator membranes, this work reports on porous poly(vinylidene fluoride-co-trifluoroethylene) - P(VDF-TrFE)- membranes with surface pillar microstructures. Separators with tailored pillar diameter, height and bulk thickness were fabricated by template patterning and computer simulations, allowing to evaluate the effect of the pillar microstructure characteristics on battery performance. It is shown that the different pillar microstructures of the separators affect the uptake value (150-325%), ionic conductivity value (0.8-1.6 mS·cm-1) and discharge capacity of the lithium ion batteries (LIB) when compared with the separator without pillars. The experimental charge-discharge behavior demonstrates that the pillar parameters affect battery performance and the best microstructure leading to 80 mAh·g-1 at 2C. Battery performance can be thus optimized by adjusting pillar diameter, height and bulk thickness of the separators keeping its volume constant, as demonstrated also by the simulation results. The parameter with most influence in battery performance is the bulk thickness of the separator, allowing to obtain a maximum discharge capacity value of 117.8 mAh·g-1 at 90C for a thickness of 0.01 mm. Thus, this work shows that the optimization of the pillar microstructure of the separator membranes allows increasing the capacity towards a new generation of high-performance LIBs.

Proteomic investigation of the effects of weight loss in the gastrocnemius muscle of wild and NZW rabbits via 2D-electrophoresis and MALDI-TOF MS.

The study of changes within the key agents regulating metabolism during genetic upgrading because of selection can contribute to an improved understanding of genomic and physiological relationships. This may lead to increased efficiencies in animal production. These changes, regarding energy and protein metabolic saving mechanisms, can be highlighted during food restriction periods. In this study, a 20% weight reduction was induced in two rabbit breeds: New Zealand white, a selected meat producer (Oryctolagus cuniculus cuniculus), and Iberian wild rabbit (Oryctolagus cuniculus algirus), with the aim of determining differential protein expression in the gastrocnemius muscle within control (ad libitum) and restricted diet experimental animal groups, using techniques of two-dimensional gel electrophoresis and peptide mass fingerprinting. Results show that L-lactate dehydrogenase, adenylate kinase, beta enolase and alpha enolase, fructose bisphosphate aldolase A and glyceraldehyde 3-phosphate dehydrogenase, which are enzymes involved in energy metabolism, are differentially expressed in restricted diet experimental animal groups. These enzymes are available to be further tested as relevant biomarkers of weight loss and putative objects of manipulation as a selection tool towards increasing tolerance to weight loss. Similar reasoning could be applied to 2D gel electrophoresis spots corresponding to the important structural proteins tropomyosin beta chain and troponin I. Finally, a spot identified as mitochondrial import stimulation factor seems of special interest as a marker of undernutrition, and it may be the object of further studies aiming to better understand its physiological role.

The effect of weight loss on protein profiles of gastrocnemius muscle in rabbits: a study using 1D electrophoresis and peptide mass fingerprinting.

The study of physiological changes occurring during selection contributes to an improved understanding of relationships leading to efficiencies in animal production. To investigate the effects of food restriction in gastrocnemius muscle protein expression, 20% weight reduction was induced in New Zealand White (meat producing) and wild rabbits, using one-dimensional gel electrophoresis and peptide mass fingerprinting. Lower expression levels of myosin heavy chains were found in the Wild Rabbits Restricted Group, while myosin light chain and alpha-crystallin proteins were not detected in restricted groups. Glyceraldeyde-3-phosphate dehydrogenase and glycogen phosphorylase expression levels were similar for all experimental groups. Phosphopyruvate hydratase beta was not detected in the wild rabbit restricted diet group. Pyruvate kinase levels were 50% lower in the New Zealand Restricted group. LIM protein detection was absent in the control New Zealand group. Results also show relevance of actin in preserving muscle structure in depressed food availability, the sensitivity of both myosin light chain and alpha-crystallin protein to restricted feed and the role of PK in the resistance of New Zealand rabbits to food restriction.