Mycoplasma hyopneumoniae colonization of pigs sired by different boars

Differences in Mycoplasma hyopneumoniae colonization were evaluated in experimentally inoculated pigs sired by 3 different boars of the same genetic line. Forty-six pigs were used, including a treatment group and positive and negative control groups. The pigs were intratracheally inoculated with an M. hyopneumoniae suspension or with Friis media as a placebo. To evaluate differences in the magnitude of colonization during a 35-day period, nasal and tracheal swabs were collected weekly and tested by nested polymerase chain reaction (N-PCR). Temperature, weight and circulating antibodies were measured for 35 days. At 11 and 35 d postinoculation the pigs were necropsied and macroscopic and microscopic lesions were determined. A section of bronchus was tested by the indirect immunofluorescence test (IFAT), scanning electron microscopy (SEM) and N-PCR. The N-PCR results from the nasal and tracheal swabs showed that the pigs sired by one boar (B3) had a distinctive colonization pattern, different from that of the pigs from the other 2 boars and from the positive controls. SEM studies demonstrated that at 35 d postinoculation a higher proportion of B3 pigs had lower numbers of mycoplasmas attached to the cilia compared with B1 and B2 offspring. No significant differences were observed in temperature and weight gain among groups by ANOVA; however, with use of a 2 × 2 table, temperature differences were observed between pigs sired by boars B1 and B2 at 4 d postinoculation. No pigs seroconverted, showed gross or microscopic lesions, or had positive IFAT results. These results provide evidence of differences in patterns of colonization between pigs sired by different boars, suggesting a possible genetic effect.     

Humoral response (IgG) of goats experimentally infected with Fasciola hepatica against cysteine proteinases of adult fluke

The use of cysteine proteinases from Fasciola hepatica adult flukes for the serodiagnosis of caprine fasciolosis by means of an indirect ELISA test was studied. Two proteolytic fractions from adult fluke homogenates, with apparent molecular weights of 28 and 34 kDa (P28 and P34 respectively), were characterised as cysteine proteinases using azocasein assays and gelatin gel analysis. Both P28 and P34 fractions were electroluted and used as antigens in two different indirect ELISA tests. Serum IgG levels against P28 and P34 in goats given an experimental primary infection with 200 metacercariae or in goats given two experimental infections with 200 metacercariae were determined and compared with those observed in an uninfected control group. ELISA tests using both cysteine proteases showed a rapid and consistent detection of specific IgG in all experimentally infected goats. The IgG response to P28 was the first to be detected as early as 2-3 weeks post-infection and remained elevated throughout the experiment. The response to P34 was detected later (4-6 wpi) and disappeared in some animals at 18 wpi, while flukes were still present in the bile ducts. No significant differences were observed between the anti-P28 and anti-P34 IgG responses between animals receiving a primary or a challenge infection. The results of our study, although preliminary, are promising since the P28 ELISA described here may be a reliable method for the immunodiagnosis of F. hepatica infection in goats.     

Activity of glutathione S-transferase toward some herbicides and its regulation by benoxacor in non-embryogenic callus and in vitro regenerated tissues of Zea mays

A procedure was developed to obtain non-embryogenic callus and regenerated lines from root segments of Zea mays grown in aseptic conditions. The activity of glutathione-S-transferases (GSTs), for non-embryogenic callus, was determined toward 1-chloro-2,4-dinitrobenzene (CDNB) and it was compared with that obtained for corn seedlings grown without hormones. For the callus masses, increases of specific activity toward CDNB and the kinetic parameter V_max were observed with respect to corn seedlings. The procedure permitted the regenerating of tissues from callus explants, therefore the GST(CDNB) activity and the effect of the safener benoxacor on its expression were investigated for the regenerated tissues grown in agarized substrate and in liquid medium. These explants showed a constitutive GST(CDNB) activity higher than corn seedlings and this activity was increased, for both tissues, in response to the presence of the safener benoxacor in the growing medium. The GST activity for the above tissues was also assayed toward benoxacor and terbuthylazine, metolachlor and fluorodifen herbicides. Measurable GST activity was found toward some of the above chemicals and it was found to be significantly enhanced in response to benoxacor treatment.     

一针注射疗法可减少猪群的应激,增加畜牧场的收益

毫无疑问,应激是影响肉食品动物生产一个重要因素。处于应激的动物对疾病更敏感,生产低质量的肉类产品,生长速度和生产性能很可能达不到其正常的指标。避免非必要的应激并不是仅仅对动物福利有利:它也能确保养猪场取得良好的商业利润。     

Effects of month of breeding on reproductive efficiency of Holstein cows and heifers inseminated with sex-sorted or conventional semen in a hot environment

The main objective of this study was to assess the effect of month of breeding on reproduction performance of Holstein heifers and cows inseminated with sex-sorted or conventional semen in a hot environment. Pregnancy per artificial insemination (P/AI; 64,666 services over an 8-year period) both in heifers (n?=?22,313) and cows (n?=?42,353) from a large dairy herd in northern Mexico (26°N) were evaluated with the GENMOD procedure of SAS, with respect to month of AI. Overall, P/AI with sex-sorted semen was greater (P?<?0.01) in heifers (41.6 %) than cows (17.3 %). P/AI for cows serviced with conventional semen was 10 % points higher (P?<?0.01) in January and December (31 vs. 21 %) than cows serviced with sex-sorted semen. While there was no difference in P/AI between the sex-sorted sperm and conventional semen in cows inseminated in July (16 and 18 %, respectively), P/AI plummeted for both groups of cows during the summer and fall (more severe heat stress). P/AI was not different between heifers serviced with sex-sorted or conventional semen during the hottest months of the year (July to October). However, during the coldest month of the year (January and February), P/AI was 10 percentage points greater (P?<?0.01) in heifers serviced with conventional than sex-sorted semen. It was concluded that in this hot climate cow and heifer fertility declined in the summer and fall when inseminated with conventional semen. However, the use of sex-sorted semen during summer and fall did not compromise the breeding success in heifers. Thus, this data suggest that sex-sorted semen promotes some embryonic thermoprotective mechanism, which leads to a marginal summer and fall fertility depression with this type of semen in this particular hot environment.     

Milk Yield of Holstein Cows Induced into Lactation Twice Consecutively and Lactation Curve Models Fitted to Artiifcial Lactations

Nineteen multiparous barren Holstein cows were subjected to an induction of lactation protocol for 21 d administering estradiol cypionate （2 mg kg-1 of body weight （BW） d-1, on day 1 to 14）, progesterone （0.10 mg kg-1 of BW, on day 1 to 7）, lfumethasone （0.03 mg kg-1 of BW, on day 18 to 20） and recombinant bovine somatotropin （rbST;500 mg per cow, on day 1, 6, 16 and 21）. At the end of lactation and with a minimum of a 2-mon dry period, the same cows were again hormonally induced into lactation. Cows in both lactations were not artiifcially inseminated, they were milked 3 times daily and received rbST throughout lactation. Mean accumulated milk yield at 305 d in milk （DIM） did not differ between the ifrst and second induced lactations （（9 710 ＆#177;1 728） vs. （9 309＆#177;2 150） kg;mean＆#177;SD）. Total milk yield （（12 707＆#177;3 406） vs. （12 306＆#177;4 218） kg;mean＆#177;SD） and lactation length （（405＆#177;100） vs. （410＆#177;91） d;mean＆#177;SD） were not different between the ifrst and second induced lactations. In a second study, 15 empirical models including exponential, power law, yield-density, sigmoidal and miscellaneous models were compared for their suitability by modeling 12-mon （n=334）, 18-mon （n=164） and 29-mon （n=22） lactation cycles of Holsteins cows induced into lactation and treated with rbST throughout the lactation. Hoerl （Y=ab1/xxc）, Wood （Y=axb exp（cx）） and Dhanoa （Y=ax（bc）exp（cx）） models were equally suitable to describe 12-mon lactations. An exponential model with ifve parameters （Y=exp（a＋bx＋cd2＋e/x）） showed the best ift for milk yield for 18-mon lactations. The rational model （Y=a＋bx/1＋cx＋dx2） was found to produce the closest ift for 29-mon lactations. It was concluded that, with the protocol used in the present study, multiparous cows respond favorably to a second cycle of induced lactation, with milk yield similar to that experienced during the ifrst cycle. Thus, dairy producers might be able to lengthen the productive life of infertile high producing cows with a renewal of artiifcial lactation, which would imply an overall reduction in voluntary culling of cows. Also, various equations used to describe the lactation curves demonstrated the potential for iftting monthly milk records of Holstein cows with prolonged lactations and induced hormonally into lactation.     

Self-assembly of large and small molecules into hierarchically ordered sacs and membranes

We report here the self-assembly of macroscopic sacs and membranes at the interface between two aqueous solutions, one containing a megadalton polymer and the other, small self-assembling molecules bearing opposite charge. The resulting structures have a highly ordered architecture in which nanofiber bundles align and reorient by nearly 90 degrees as the membrane grows. The formation of a diffusion barrier upon contact between the two liquids prevents their chaotic mixing. We hypothesize that growth of the membrane is then driven by a dynamic synergy between osmotic pressure of ions and static self-assembly. These robust, self-sealing macroscopic structures offer opportunities in many areas, including the formation of privileged environments for cells, immune barriers, new biological assays, and self-assembly of ordered thick membranes for diverse applications.     

Distribution of the Mallorcan midwife toad (Alytes muletensis) in relation to landscape topography and introduced predators

The endemic midwife toad of Mallorca (Alytes muletensis) is restricted to a small number of breeding populations in the mountainous northwest of the island. The decline of the species has been attributed to the impacts of introduced species such as the viperine snake (Natrix maura) and green frog (Rana perezi), and toads may be surviving only in areas that are suboptimal for these predators. The influence of landscape features (elevation, aspect and maximum slope) on the distribution of toads and associated predators was therefore investigated using GIS. The presence of toads was positively associated with steep slopes. At sites where they occurred with toads, the distribution of predators was negatively associated with elevation. Reproductive success within toad populations was strongly associated with the number of pools at each site, while reproductive success within individual pools was positively associated with elevation. These findings may be used to optimise the design and location of future reintroduction sites.     

Soil physical quality of a Brazilian Oxisol under two tillage systems using the least limiting water range approach

Plant growth is directly affected by soil water, soil aeration, and soil resistance to root penetration. The least limiting water range (LLWR) is defined as the range in soil water content within which limitations to plant growth associated with water potential, aeration and soil resistance to root penetration are minimal. The LLWR has not been evaluated in tropical soils. Thus, the objective of the present study was to evaluate the LLWR in a Brazilian clay Oxisol (Typic Hapludox) cropped with maize (Zea mays L. cv. Cargil 701) under no-tillage and conventional tillage. Ninety-six undisturbed soil samples were obtained from maize rows and between rows and used to determine the water retention curve, the soil resistance curve and bulk density. The results demonstrated that LLWR was higher in conventional tillage than in no-tillage and was negatively correlated with bulk density for values above 1.02 g cm⁻³. The range of LLWR variation was 0–0.1184 cm³ cm⁻³ in both systems, with mean values of 0.0785 cm³ cm⁻³ for no-tillage and 0.0964 cm³ cm⁻³ for conventional tillage. Soil resistance to root penetration determined the lower limit of LLWR in 89% of the samples in no-tillage and in 46% of the samples in conventional tillage. Additional evaluations of LLWR are needed under different texture and management conditions in tropical soils.