Adrenal-gonad interactions in cattle. Corpus luteum function in intact and adrenalectomized heifers

To determine the effect of the hyperadrenal state on corpus luteum (CL) function, we treated intact and adrenalectomized (ADRX) heifers with adrenocorticotropin (ACTH) and hydrocortisone. ACTH treatment of intact heifers by infusion of 1 mg alpha 1-24 ACTH/24 hr from day 2 to 25 of an estrous cycle increased progesterone concentrations in plasma to 4 +/- .52 ng/ml plasma on days 3 to 4. Thereafter, progesterone concentrations declined, indicating severe suppression of CL function as compared to that of control heifers. Similar infusions of ACTH to ADRX heifers did not alter CL function as reflected by progesterone concentrations in jugular plasma. Infusion of ADRX animals with hydrocortisone succinate (100 mg/24 hr) decreased progesterone in plasma during the cycle, with maximum values averaging less than 4 ng/ml, compared to concentrations of 6 to 7 ng/ml in control ADRX heifers. Chronic administration of ACTH or hydrocortisone to heifers caused a decreased progesterone secretion during the luteal phase of the estrous cycle. On the basis of these results, we suggest that stress, as indicated by the hyperadrenal state, could inhibit progesterone secretion by the corpus luteum.     

Optimization of fixation methods for image analysis of the hepatopancreas in whiteleg shrimp,Penaeus vannamei (Boone)

Pathology in penaeid shrimps relies on histology, which is subjective, time‐consuming and difficult to grade in a reproducible manner. Automated image analysis is faster, objective and suitable for routine screening; however, it requires standardized protocols. The first critical step is proper fixation of the target tissue. Bell & Lightner's (A Handbook of Normal Penaeid Shrimp Histology, 1988, The World Aquaculture Society, Baton Rouge) fixation protocol, widely used for routine histology of paraffin sections, is not optimized for image analysis, and no protocol for frozen sections is described in the available literature. Therefore, the aim of this study was to optimize fixation of the hepatopancreas (HP) from whiteleg shrimp (Penaeus vannamei) for both paraffin and frozen sections using a semiquantitative scoring system. For paraffin sections, four injection volumes and three injection methods were compared, for frozen sections, four freezing methods and four fixation methods. For paraffin sections, optimal fixation was achieved by increasing threefold the fixative volume recommended by Bell and Lightner, from 10% to 30% of the shrimp body weight, combined with single injection into the HP. Optimal fixation for frozen sections was achieved by freezing the cephalothorax with liquid nitrogen, followed by fixation of the section with 60% isopropanol. These optimized methods enable the future use of image analysis and improve classical histology.     

Energy and protein requirements for growth of Holstein × Gyr heifers

There is little information regarding the nutritional requirements for dairy heifers, leading the majority of nutrient requirement systems to consider dairy heifers to be similar to beef heifers. Therefore, we evaluated the muscle protein metabolism and physical and chemical body composition of growing Holstein × Gyr heifers and estimated the energy and protein requirements. We performed a comparative slaughter experiment with 20 Holstein × Gyr heifers at an initial body weight of 218 ± 36.5 kg and an average age of 12 ± 1.0 months. Four heifers were designated as the reference group, and the 16 remaining heifers were fed ad libitum . The 16 heifers were distributed using a completely randomized design in a 2 × 2 factorial arrangement with two roughages (corn silage or sugarcane) and two concentrate levels (30 or 50%) for 112 days. Greater (p  <  0.05) values for fractional rates of muscle protein synthesis, degradation and accretion were observed for heifers that were fed 50% concentrate. The following equations were obtained to estimate the net energy for gain (NE _g) and net protein for gain (NP _g): NE _g (Mcal/day) = 0.0685 × EBW ^0.75 × EBWG ^1.095 and NP _g (g/day) = 203.8 × EBWG  ? 14.80 × RE , respectively, in which EBW is the empty body weight, EBWG is the empty body weight gain and RE is the retained energy. We concluded that increased rates of protein turnover are achieved when a greater quality diet is provided. In the future, these results can be used to calculate the nutritional requirements for growth of Holstein × Gyr heifers after equation validation rather than using the recommendations provided by other systems, which use values developed from beef heifers, to determine the nutritional requirements of dairy cattle.     

Effects of short-term conservation management practices on soil organic carbon fractions and microbial community composition under a rice-wheat rotation system

The objective of this study was to investigate the effects of short-term (less than 2 years) conservation managements [no-tillage (NT) and crop residue returning] on top soil (0–5 cm) microbial community composition and soil organic C (SOC) fractions under a rice-wheat rotation at Junchuan town of Hubei Province, China. Treatments were established following a split-plot design of a randomized complete block with tillage practices [conventional tillage (CT) and NT] as the main plot and residue returning level [no residue returning (0) and all residues returned to fields from the preceding crop (S, 2,146 kg C ha^?1)] as the subplots. The four treatments were CT with or without residue returning (CT0 and CTS) and NT with or without residue returning (NT0 and NTS). The abundances of microbial groups [total FLFAs, fungal biomass, bacterial biomass, fungal biomass/bacterial biomass (F/B), monounsaturated fatty acids/saturated fatty acids (MUFA/STFA), and microbial stress] were determined by phospholipid fatty acid (PLFA) analysis of soil. The ratio of MUFA/STFA reflects aeration of soil and greater MUFA/STFA means better aeration condition of soil. Moreover, the microbial stress, the ratio of cy19:0 to 18:1ω7, was regarded as an indicator of physiological or nutritional stress of microbial community. PLFA profiles were dominated by the fatty acids iC15:0 (9.8 %), C16:0 (16.5 %), 10Me17:0 (9.9 %), and Cyc19:0 (8.3 %), together accounting for 44.6 % of the total PLFAs. Compared with CT, NT significantly increased microbial biomass C (MBC) by 20.0 % but did not affect concentrations of total organic C (TOC), dissolved organic C (DOC), easily oxidizable C (EOC), and SOC of aggregates. Residue returning significantly increased MBC by 18.3 % and SOC content of 2–1-mm aggregate by 9.4 %. NT significantly increased total PLFAs by 9.8 % and fungal biomass by 40.8 % but decreased MUFA/STFA by 15.5 %. Residue returning significantly enhanced total PLFAs, bacterial biomass, fungal biomass, F/B, and MUFA/STFA by 31.1, 36.0, 95.9, 42.5, and 58.8 %, respectively, but decreased microbial stress by 45.9 %. Multivariate analysis (redundancy analysis and partial correlation analysis) indicated that SOC of 2–1-mm aggregate was related to changes in the composition of soil microbial groups, suggesting that SOC of 2–1-mm aggregate was sensitive to changes in soil microbial community composition affected by short-term conservation management practices in our study.     

Inheritance of resistance to Meloidogyne enterolobii in <Emphasis Type="Italic">Psidium guajava</Emphasis> x <Emphasis Type="Italic">P. guineense</Emphasis> hybrid

Inheritance of the resistance to nematodes has been studied on many different crops, however to our knowledge, no data are available for guava species. The basic genetic resistance parameters to Meloidogyne enterolobii are estimated in the current research in order to guide the development of genotypes resistant to the pathogen. The parental plants, F1 and F2 from a Psidium guajava x P. guineense cross were assessed for the presence or absence of galls and for the number of eggs and juveniles in the root system at the 120th and 240th days after inoculation with 10,000 eggs and juveniles of the nematode. At the age of nine years, the P. guineense plant remained without nematode attack symptoms, whereas the maternal plant was destroyed by the pathogen. The F1 generation showed 270 plants with reproduction factor (RF) <0.322, and there were tiny galls in only 16 plants. The segregation for the presence or absence of galls in the root system in generation F2 was 9:7, wherein the χ² values were 0.78 and 2.66, respectively, at the 120th and 240th days after inoculation, whereas the segregation for RF was 15:1, wherein the χ² values were 2.76 and 1.18, respectively, at the 120th and 240th days. These results indicate epistatic interaction between two genes: in RF < 1 only one allele sets the resistance to the pathogen. The broad sense heritability of RF, estimated to the two assessments was 0.97, and it also indicates a simple inheritance of resistance to M. enterolobii.     

Differential diagnosis of dog hookworms based on PCR-RFLP from the ITS region of their rDNA

Species of Ancylostoma infecting dogs and sometimes humans are sympatric in many parts of the world. The establishment of a specific molecular diagnostic tool is important, not only to refine information for epidemiological studies, but also to evaluate the efficacy of vaccine programmes and assist in the development of specific drug treatments. The ITS region from 20 specimens of A. braziliense, collected from three separate geographical areas of Brazil, and from 10 specimens of A. caninum, collected from the same area in Brazil were sequenced and analyzed. Alignment of sequences showed that this gene is highly conserved. The intraspecific polymorphism for both species was less then 1%, whereas the interspecific polymorphism was 6.2, 7.3 and 9.4% between A. ceylanicum and A. braziliense; A. caninum and A. ceylanicum and A. ceylanicum and A. braziliense, respectively. Among the three species it was 12.3%. This revealed the ITS region as highly conserved and consequently a good molecular marker for diagnostic studies. In this work, four restriction enzymes were used in a PCR-RFLP using the ITS region of rDNA, to establish a differential diagnosis which discriminates between three Ancylostoma species, A. braziliense, A. caninum and A. ceylanicum. The best pattern was given by the HinfI enzyme, which produced different fragment sizes for each of the three species. Furthermore, the diagnostic tool differentiates DNA extracted directly from faeces of Ancylostoma-infected dogs.     

Suitability of different artificial diets for development and survival of stages of the predaceous ladybird beetle <Emphasis Type="Italic">Eriopis connexa</Emphasis>

The ladybug Eriopis connexa (Germar) (Coleoptera: Coccinellidae) is an important natural enemy of various pests. The potential of rearing it on 17 different diets was evaluated. The percentage of E. connexa adults was higher when its larvae received only eggs of Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) after freezing for 1 day (92.5%) or combined in artificial diets with honey and water (82.5% to 100.0%). The viability from larvae to adult was 72.5% with eggs of A. kuehniella (after 1 day’s freezing) plus an artificial diet based on pet food. No adults of E. connexa were obtained with artificial diets as a stand-alone food source. The duration of the larval period to adult of this predator was longer, but with low viability, with only A. kuehniella eggs (after 6 months’ freezing) or with eggs + artificial diets. Eggs of A. kuehniella (after 1 day’s freezing) supplied separately or along with artificial diets were more appropriate to rear E. connexa and both diets can be used for mass rearing of this natural enemy.     

Prevalence and risk factors for agents causing diarrhea (Coronavirus,Rotavirus, Cryptosporidium spp., Eimeria spp., and nematodes helminthes) according to age in dairy calves from Brazil

The present study attempted to verify the prevalence of and risk factors for diarrhea-causing agents in dairy calves from Brazil. Additionally, ages with a higher risk of occurrence for each agent were verified by means of the receiver operating characteristic (ROC) curve. The collections were performed on 39 farms, belonging to 29 municipalities located in eight states of Brazil. It was possible to conclude that the prevalence of Coronavirus, Rotavirus, Cryptosporidium spp., Eimeria spp., and nematodes was 7.20% (95% CI 4.54–9.78), 6.37% (95% CI 3.85–8.89), 51.52% (95% CI 45.26–55.57), 3.46% (95% CI 2.24–4.67), and 3.46% (95% CI 2.24–4.67), respectively. Ages with higher probabilities of occurrence of these diseases in calves were <?10, >?8, >?6, >?37, and >?36 days, respectively. Diarrhea occurred more significantly (P?<?0.0001) in animals less than 21 days old and mainly on those receiving milk through automatic feeders (P?<?0.001). Cryptosporidium spp. were a risk factor for the occurrence of Rotavirus, and vice versa (P?=?0.0039) and presented a positive correlation with Coronavirus (P?=?0.0089). Calves that drink water from rivers, streams, and ponds had a higher chance of being infected by Eimeria spp. (P?<?0.0001), as well as developing infection by nematodes (P?<?0.0001). The results found in this study highlight the importance of studying the agents of diarrhea together, once they act as coinfection where the losses triggered for the owners will involve some of these agents simultaneously.

     

Sequence variation identified in the 18S rRNA gene of Theileria mutans and Theileria velifera from the African buffalo (Syncerus caffer)

The African buffalo (Syncerus caffer) is a natural reservoir host for both pathogenic and non-pathogenic Theileria species. These often occur naturally as mixed infections in buffalo. Although the benign and mildly pathogenic forms do not have any significant economic importance, their presence could complicate the interpretation of diagnostic test results aimed at the specific diagnosis of the pathogenic Theileria parva in cattle and buffalo in South Africa. The 18S rRNA gene has been used as the target in a quantitative real-time PCR (qPCR) assay for the detection of T. parva infections. However, the extent of sequence variation within this gene in the non-pathogenic Theileria spp. of the Africa buffalo is not well known. The aim of this study was, therefore, to characterise the full-length 18S rRNA genes of Theileria mutans, Theileria sp. (strain MSD) and T. velifera and to determine the possible influence of any sequence variation on the specific detection of T. parva using the 18S rRNA qPCR. The reverse line blot (RLB) hybridization assay was used to select samples which either tested positive for several different Theileria spp., or which hybridised only with the Babesia/Theileria genus-specific probe and not with any of the Babesia or Theileria species-specific probes. The full-length 18S rRNA genes from 14 samples, originating from 13 buffalo and one bovine from different localities in South Africa, were amplified, cloned and the resulting recombinants sequenced. Variations in the 18S rRNA gene sequences were identified in T. mutans, Theileria sp. (strain MSD) and T. velifera, with the greatest diversity observed amongst the T. mutans variants. This variation possibly explained why the RLB hybridization assay failed to detect T. mutans and T. velifera in some of the analysed samples.