Transgenic rabbits provide a useful biological model for the study of the regulation of mammalian genes. However, transgene integration efficiency has generally been low. Here we present a first attempt to increase the integration rate of exogenous DNA into the rabbit genome, using a double pronuclei microinjection method. Pronuclear stage rabbit embryos were recovered from superovulated NZW females, 19-20 h after hCG injection. About 5 microg/mL of exogenous DNA solution was microinjected either into one pronucleus (single microinjection, SM) or into both pronuclei (double microinjected, DM). The transgene consisted of a 2.5 kb murine whey acidic protein promoter (mWAP), 7.2 kb cDNA of the human clotting factor VIII (hFVIII), and 4.6 kb that of 3' flanking sequences of the mWAP gene. The in vitro survival of DM embryos to the blastocyst stage was lower than that of SM embryos (68 vs. 89%). Similar results were obtained using EGFP as a control gene construct. However, there was no difference in the percentage of embryos that developed into live offspring using DM (25%) vs. SM (26%). The integration frequency of mWAP-hFVIII into the genome of transgenic rabbits was 3.3% (1/30) upon SM and 8.1% (4/49) at DM (p < 0.05). All founders transmitted the transgene to their offspring in a Mendelian fashion. The SM founder female secreted 87.4 microg/mL rhFVIII in milk, with an activity of 0.594 IU/mL. The DM founder female produced 118 microg/mL rhFVIII, with activity values of 18 IU/ mL. This is the first report of transgenic rabbit production using a double microinjection technique. Our preliminary results suggest that this method can increase the efficiency of production of transgenic rabbit founders, giving a higher integration rate than single microinjection.

This study was conducted to investigate the effect of heat stress (i.e., elevated ambient temperature -Ta; 36 °C ± 3 °C) on growth performance, mortality rate, and on some haematological and biochemical parameters in different categories of gender and age of New Zealand White (NZW) rabbits. Animals were divided into two main groups (control and treatment), in each group there were 56 rabbits: adult females (n = 20), adult males (n = 4), growing females (n = 16), and growing males (n = 16). Results revealed that total and daily feed intake, feed conversion ratio, and total and daily gain in body weight for growing NZW rabbits were affected negatively by elevated Ta. Decreases in feed intake led to less protein biosyntheses and less fat deposition, which led to lower body weight gain. These observations were made in growing and adult rabbits of both genders. Analysis showed that red blood cell (RBC) counts showed alterations. Packed cell volume (PCV) (in adult females and males), white blood cell (WBC) counts (in growing females), lymphocytes (in growing males), monocytes (in growing females and adult males), basophils (in growing females and growing and adult males) were significantly (P < 0.05) decreased, and total proteins (TP) (in adult females), glucose (Glu) (in adult females), and calcium (Ca 2+ ) (in growing males and females) were significantly (P < 0.01) lower in the experimental group. Furthermore, elevated Ta increased the mortality rate (MR) in both age groups. The mortality rate was 30.36% for growing and adult rabbits of the experimental group, compared with 7.14% for the control group, and was 25% for adult compared with 34.38% for growing experimental rabbits. Exposure of NZW rabbits of both ages and genders to elevated ambient temperature (36°C ± 3 °C), negatively affected their internal homeostasis which was reflected in their growth rate and various physiological signs.

The seeds of most plants are rich in various nutrients and can provide a lot of useful health benefits. The objective of this study was to determine and compare differences in fat, fatty acids, crude protein and amino acids concentrations for chia and flax seeds. Study was carried out using brown and gold seeds of Flax (Linum usitatissimum L.) and Chia (Salvia hispanica L.). The mean protein content in tested seeds ranged from 211.8 to 252.5 g/kg dry matter and in chia seed was about 13.10% higher than the average value of crude protein content in brown and gold flax seed (223.25 g/kg dry matter). Differences in the content of individual amino acids among the seeds were not statistically significant (P <0.05), except that for glutamic acid. Percentage of the essential to the total amino acids, which is considered as indicator of protein quality, was 37.87%, 33.76% and 35.18%, for chia, brown and gold flax seed respectively, which demonstrates the high quality of these proteins. The average fat content of flax seeds was about 71.42 g/kg higher than that in chia seed (321.37 g/kg dry matter). The fatty acids composition showed the presence of palmitic, stearic, oleic, linoleic, α- linolenic and arachidic fatty acids in all tested samples. The α-linolenic acid constitutes on average 54.38% of the total fatty acids of flax seeds and 63.79% of chia seed, and for linoleic acid it was 15.30% and 18.89%. All seeds had low n-6 PUFA / n-3 PUFA ratio. Results of our study confirmed the excellent quality of protein and fat in chia seed, brown and gold flax seed samples. There was no significant effect of the flax seed coat colour for all measured values. Chia seed is the richest of n-3 PUFA α-linolenic fatty acid in the vegetable world. Both, flax seed and chia seed are the good choice of healthy food to maintain a balanced serum lipid profile. It must be pointed that flax seeds must be ground to release their nutrients, but chia seeds do not.

Effects of a 50 Hz extra-low frequency electromagnetic field (ELF EMF) on in vitro rabbit spermatozoa motility were analyzed, as well as the effect on fertilization rates after insemination. Pooled semen samples and a control were exposed to 50 Hz ELF EMF. The difference of the samples of the test groups G1 and G2 with the control group CG (75.56%) for spermatozoa motility were found to be significant (P < 0.01). Differences were significant (P < 0.01) for curvilinear velocity (VCL) between the test group G3 (122.38 microm/s) and the control group CG (112.02 microm/s). Hormonally stimulated adult (9-12 months) females (n = 140) were inseminated with semen samples from G1, G2, G3 and CG (0.88 x 109 spermatozoa/0.5 mL average insemination portion) immediately after ELF EMF exposure and fertilization (kindling) rates were calculated. For the G2 it was 54.28% data indicate 50 Hz ELF EMF induced alterations of spermatozoa motility and kindling rate in rabbits, therefore influencing fertility.

Simonová M.P., Chrastinová Ľ., Mojto J., Lauková A., Szábová R., Rafay J. (2010): Quality of rabbit meat and phyto-additives. Czech J. Food Sci., 28: 161-167.The consumption of healthy and nutritive food (rich in proteins and low in cholesterol and lipid contents) is a preferred factor with the contemporary consumers. In addition, natural alternatives are requested to replace the additives used up to now but recently banned. To reach the above given condition, phyto-additives represent a good alternative. The aim of this study was to examine the physicochemical properties and amino acid composition of rabbit meat after the enrichment of rabbit diet with oregano, sage, and Eleutherococcus senticosus extracts, and to make a comparison with the commercial product XTRACT and control samples (without plant extracts). The addition of oregano and sage extracts as well as El. senticosus in the rabbit diet positively influenced the physicochemical properties of rabbit meat by increasing its energy value (P < 0.05 -sage). Supplementing rabbits feed with oregano and sage extracts led to an improvement on the amino acid composition (P < 0.01; P < 0.001 -serine). These findings are also supported by the good health state of rabbits. Outgoing from these results, the diet enriched with the plant extracts is beneficial for the health state of rabbits involving the nutritional quality of rabbit meat in connection with consumers. Nowadays, consumers are increasingly interested in a healthy lifestyle, e.g. energy and nutritional values of foods, which are rich in protein and low in cholesterol and lipid contents. From the nutritional point of view, rabbit meat is flavourful and easily digested, with high nutritional and dietetic properties: this meat contains 20-21% of proteins, unsaturated fatty acids (oleic and linoleic; 60% of all fatty acids), potassium, phosphorus, and magnesium, it has low concentrations of fat, cholesterol, and sodium (Bielanski et al. 2000;Dalle Zotte 2002;Hermida et al. 2006). That is why the rabbit meat is better digested as compared to other kinds of meat (beef, lamb, or pork;Enser et al. 1996) and is recommended for consumption, e.g. for persons with cardiovascular illnesses (Hu & Willett 2002). Moreover, the energy value of rabbit meat (427-849 kJ/100 g of fresh meat) is comparable to various commonly consumed sorts of red meat (Dalle Zotte 2002). KeywordsThe studies concerned with the quality of rabbit meat have focused mainly on biochemical or biophysical traits such as pH, water holding capacity, or colour (Pla et al. 1998; Hernández et al. 2000). The results on the sensory properties, e.g. appearance, texture, flavour, and others, are also 162 Vol. 28, 2010, No. 3: 161-167 Czech J. Food Sci. (Lewis et al. 2003;Lauková et al. 2006;Marcin et al. 2006;Simonová et al. 2008). While most of the studies deal with the moderating effects of the environmental, feeding, genetic, and biological (age and weight) factors as well as those of technological (pre-slaughter, transportation, processing) c...