Oocyte and Embryo Quality: Effect of Origin, Culture Conditions and Gene Expression Patterns

In general, the majority of immature bovine oocytes fail to develop to the blastocyst stage following maturation, fertilization and culture in vitro. The evidence suggests that while culture conditions during in vitro embryo production can impact on the developmental potential of the early embryo, the intrinsic quality of the oocyte is the key factor determining the proportion of oocytes developing to the blastocyst stage. In addition, evidence suggests that the period of post‐fertilization embryo culture is the most critical in determining blastocyst quality. This paper reviews the current literature, with emphasis on the bovine model, demonstrating evidence for an effect of oocyte origin and/or in vitro maturation conditions on the developmental capacity and gene expression patterns in the oocyte. Furthermore, the well‐documented effects of post‐fertilization culture environment on embryo gene expression and quality are highlighted.     

Seminal Plasma Composition from Ejaculates Collected by Artificial Vagina and Electroejaculation in Guirra Ram

This study was conducted to evaluate changes in ram seminal plasma composition from ejaculates obtained using artificial vagina (AV) and electroejaculation (EE). To address this question, we assessed the effect of semen collection method on volume, sperm concentration, sodium concentration, potassium concentration, sodium/potassium ratio, total protein content and protein profile using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and 2-D polyacrylamide gel electrophoresis. The main findings from this study were: (i) similar volume was obtained, while sperm concentration was significantly lower for EE method; (ii) potassium and sodium/potassium concentration ratio were not influenced by recovery method, while sodium concentration increased significantly when semen was recovered using EE; (iii) approximately 80% of the total relative seminal plasma protein is represented by four protein fractions of molecular weights around 15, 21, 24 and 50 kDa and there were not differences and (iv) focussing the two-dimensional SDS-PAGE gel on the 10–25 kDa rank, the image analysis software detected around 22 spots with isoelectric points ranging from 5.1 to 6.1. Two protein spots (15 kDa and 5.5 and 22 kDa and 5.2 for molecular weight and isoelectric point respectively) increased significantly when semen was recovered using EE. One spot protein with molecular weight around 25 kDa and isoelectric point of 5.2 were only found in the seminal plasma from the semen recovery by AV. As it was demonstrated, ejaculates obtained with EE modify the sodium concentration, alter two proteins concentration and induced the loss of one protein in seminal plasma.     

The dynamics of zooxanthellae populations: A long-term study in the field

Coral bleaching characterized by the expulsion of symbiotic algae (zooxanthellae) is an increasing problem worldwide. Global warming has been implicated as one cause, but the phenomenon cannot be fully comprehended without an understanding of the variability of zooxanthellae populations in field conditions. Results from a 6-year field study are presented, providing evidence of density regulation but also of large variability in the zooxanthellae population with regular episodes of very low densities. These bleaching events are likely to be part of a constant variability in zooxanthellae density caused by environmental fluctuations superimposed on a strong seasonal cycle in abundance.     

Effects of iodized feed on stress modulation in steelhead trout, Oncorhynchus mykiss (Walbaum)

In the aquaculture industry, the physiological systems of fish can be chronically stressed by various biological, chemical and physical factors. Chronic stress leads to a decrease in the overall health and growth of the fish, making them more prone to diseases. Dietary iodine has been shown to reduce this stress response in chickens and increase disease resistance in dairy cattle, but the mechanisms by which iodine affects stress resistance and immunocompetency is not completely understood and has not been extensively studied in fish. This study investigated the effects of iodized feed as a nutritional supplement in relation to stress modulation in steelhead trout (Oncorhynchus mykiss). We investigated effects on primary, secondary and tertiary stress responses by measuring plasma levels of cortisol, glucose and thyroid hormones as well as haematocrit percentage and average growth rate in steelhead trout. Iodine‐supplemented fish, on average, had lower levels of plasma cortisol and glucose and lower packed cell volumes than fish fed with regular commercial feed (P<0.05). Iodine‐supplemented fish also showed higher levels of thyroid hormones and exhibited better growth over the period of the experiment (P<0.05). It was concluded that, used with other husbandry practices, use of iodine‐supplemented feed could lead to better host defence, growth and survival in fish raised in the aquaculture industry.     

Organic carbon accumulation in a 2000-year chronosequence of paddy soil evolution

Considerable amounts of soil organic matter (SOM) are stabilized in paddy soils, and thus a large proportion of the terrestrial carbon is conserved in wetland rice soils. Nonetheless, the mechanisms for stabilization of organic carbon (OC) in paddy soils are largely unknown. Based on a chronosequence derived from marine sediments, the objectives of this study are to investigate the accumulation of OC and the concurrent loss of inorganic carbon (IC) and to identify the role of the soil fractions for the stabilization of OC with increasing duration of paddy soil management. A chronosequence of six age groups of paddy soil formation was chosen in the Zhejiang Province (PR China), ranging from 50 to 2000 years (yrs) of paddy management. Soil samples obtained from horizontal sampling of three soil profiles within each age group were analyzed for bulk density (BD), OC as well as IC concentrations, OC stocks of bulk soil and the OC contributions to the bulk soil of the particle size fractions. Paddy soils are characterized by relatively low bulk densities in the puddled topsoil horizons (1.0 and 1.2 g cm^− 3) and high values in the plow pan (1.6 g cm^− 3). Our results demonstrate a substantial loss of carbonates during soil formation, as the upper 20 cm were free of carbonates in 100-year-old paddy soils, but carbonate removal from the entire soil profile required almost 700 yrs of rice cultivation. We observed an increase of topsoil OC stocks from 2.5 to 4.4 kg m^− 2 during 50 to 2000 yrs of paddy management. The OC accumulation in the bulk soil was dominated by the silt- and clay-sized fractions. The silt fraction showed a high accretion of OC and seems to be an important long-term OC sink during soil evolution. Fine clay in the puddled topsoil horizon was already saturated and the highest storage capacity for OC was calculated for coarse clay. With longer paddy management, the fractions < 20 μm showed an increasing actual OC saturation level, but did not reach the calculated potential storage capacity.     

Impact on beef cattle productivity of infection with anthelmintic-resistant nematodes

ABSTRACT

Aims: The main goal of the current study was to evaluate, on a commercial beef cattle farm, the impact of infection with gastrointestinal nematodes resistant to both ivermectin (IVM) and moxidectin (MXD) on the productivity of calves.

Methods: Male Aberdeen Angus calves, aged 9–11 months, with faecal nematode egg counts (FEC) ≥200 epg and body weight ≥190?kg, were allocated to two herds. Herd A (n?=?90) grazed a maize-winter forage crop rotation and Herd B (n?=?90) grazed a 2-year-old Agropyrum pasture. On Day 0 in each herd, calves were randomly allocated into five groups (n?=?18), which were treated with 0.2?mg/kg IVM; 0.2?mg/kg MXD; 3.75?mg/kg ricobendazole (RBZ), both IVM and RBZ, or remained untreated. Faecal samples collected on Days ?1 and 19 were used to determine the percentage reduction in FEC, and genera of the nematodes were determined by the identification of the third-stage larvae recovered from faecal cultures. Total weight gain was determined from body weights recorded on Days ?1 and 91.

Results: Overall mean reduction in FEC was 42% for IVM, 67% for MXD, 97% for RBZ and 99% for IVM?+?RBZ. The reduction in FEC for Cooperia spp. was ≤78% for IVM and MXD, and for Haemonchus spp. was 0 and 36% for IVM and MXD, respectively, confirming the presence of parasites resistant to both anthelmintics. Only IVM?+?RBZ treatment resulted in 100% efficacy against Haemonchus spp. The overall estimated mean total weight gain for calves treated with IVM was 15.7 (95% CI?=?11.9–19.7) kg and for calves treated with IVM?+?RBZ was 28.8 (95% CI?=?25–32.5) kg (p?<?0.001). Mean total weight gain for calves treated with MXD was 23.5 (95% CI?=?19.7–27.2) kg.

Conclusions and clinical relevance: In calves naturally infected with resistant nematodes, under the production system assessed here, weight gains were lower in calves treated with anthelmintics that were moderately or highly ineffective compared to those treated with highly effective anthelmintics. These results demonstrate to farmers and veterinarians the importance of a sustainable and effective nematode control under field conditions.