Reproductive Performance of Gilts with Similar Age but with Different Growth Rate at the Onset of Puberty Stimulation

The aim of this study was to evaluate the reproductive performance of gilts that had a similar age but different weights at the onset of puberty stimulation by boar exposure at 144 days. Gilts were divided into two groups according to their lifetime growth rate from birth to approximately 144 days of age. Mean growth rates at this moment were 577 and 724 g/day for group 1 (G1; n = 58) and group 2 (G2; n = 58), respectively. After selection, gilts were weighed at approximately 155, 165 and 175 days of age, on the insemination day and at slaughter. Gilts were inseminated, on average, at 193 days of age and were slaughtered 32 days after insemination, when the number of corpora lutea and embryos were recorded. Higher growth rate gilts (G2) reached puberty earlier (155.3 vs 164.1 days; p < 0.01). More gilts of G2 group attained puberty by 190 days of age (p = 0.004) than G1 gilts (95%; 55/58 vs 76%; 44/58). The anoestrous rate, until 60 days after the onset of boar exposure was higher (p < 0.01) in G1 (19.0%; 11/58) than in G2 (3.4%; 2/58) group. However, there were no differences in the pregnancy rate (90.7 vs 94.5), ovulation rate (15.9 vs 16.5), total embryos (12.9 vs 11.7), viable embryos (12.0 vs 11.1) and embryo survival (73.7% vs 68.5%), between G1 gilts and G2 gilts, respectively (p > 0.05). High growth rate gilts attain puberty earlier and have a lower anoestrous rate than low growth rate gilts.     

Soil CO2 concentration,efflux, and partitioning in a recently afforested grassland

Relatively few studies have documented the impacts of afforestation, particularly production forestry, on belowground carbon dioxide (CO₂) effluxes to the atmosphere. We evaluated the changes in the soil CO₂ efflux—a proxy for soil respiration (Rs)—for three years following a native grassland conversion to eucalypt plantations in southern Brazil where minimum tillage during site preparation created two distinct soil zones, within planting row (W) and between-row (B). We used root-exclusion and carbon (C)- isotopic approaches to distinguish Rs components (heterotrophic-Rh and autotrophic-Ra respirations), and a CO₂ profile tube (1-m deep) to determine the concentration ([CO₂]) and isotopic C signature of soil CO₂ (δ¹³[CO₂]). The soil CO₂ efflux in the afforested site averaged 0.37 g CO₂ m^?2 h^?1, which was 56% lower than the soil CO₂ efflux in the grassland. The δ¹³CO₂ in the afforested site ranged from ? 14.1‰ to ? 29.4‰, indicating a greater contribution of eucalypt-derived respiration (both Rh and Ra) over time. Higher soil CO₂ efflux and lower [CO₂] were observed in W than B, indicating that soil preparation creates two distinct soil functional zones with respect to C cycling. The [CO₂] and δ¹³[CO₂] decreased in both zonal positions with eucalypt stand development. Although the equilibrium in C fluxes and pools across multiple rotations is needed to fully account for the feedback of eucalypt planted forests to climate change, we provide quantitative information on soil CO₂ dynamics after afforestation and show how soil preparation can leverage the feedback of planted forests to climate change.

     

Mineral Nitrogen Associated Changes in Growth and Xylem-N Compounds in Amazonian Legume Tree

In nodulated young Inga edulis plants, nodule and plant growth, nitrogen (N) in xylem sap and tissues total contents of amino acid, ureide, and nitrate were determined in response to nutrition with nitrate, ammonium, or no mineral N. Additionally, the amount of soluble sugars in the different plant tissues was quantified. It was found that mineral N improved plant growth in height and diameter especially with ammonium. However, nitrate dramatically reduced nodule dry weight on a root dry weight basis and impaired N organic transport by xylem sap. Additionally, a higher amount of amino acids was observed in the roots and nodules of plants fed with mineral N but sugar levels remained constant. Although nitrate inhibited symbiosis, data support the idea that I. edulis is able to use both molecular and mineral nitrogen during the life cycle.     

Biomarkers predictive of long-term fertility found in vaginal lipidome of gilts at weaning

A marker indicative of the fertility potential of replacement gilts early in development would decrease culling rates in the sow herd, improve sow herd reproductive efficiency, and reduce production costs. The objective of this study was to determine if vaginal lipid profiles at 21 d postnatal (PN) could predict sow reproductive performance. Vaginal swabs of the anterior vagina were taken at 21 ± 4 d PN from gilts born on a commercial sow production facility for lipidomic analysis. Animals were followed prospectively for 2 yr and assigned to reproductive performance categories based on the observation of estrus or piglets weaned per sow per year (PSY) across two farrowings. Lipids were extracted from cellular material collected with swabs taken from high fertility (HF; n = 28; ≥26 PSY) and infertile (IF; n = 34; no estrus, no pregnancy) animals, and multiple reaction monitoring profiling was used for lipidome analysis. The relative abundance of arachidonic acid (C20:4) and docosahexaenoic acid (C22:6) was lower (P < 0.05) in IF gilts than HF gilts, whereas the abundance of the free fatty acids such as cerotic (C26:0), ximenic (C26:1), and nonadecanoic (C19:0) acids was greater (P < 0.05) in IF gilts. Additionally, eicosapentaenoic acid (C20:5), a precursor of prostaglandins, was higher (P < 0.05) in IF gilts. The perspective of having a panel of lipids captured with vaginal swabs at weaning that can predict the reproductive efficiency of gilts shows promise and warrants future research in this area.     

Leaf and canopy optical characteristics as crop‐N‐status indicators for field nitrogen management in corn

The primary constraint of predicting the economic optimum nitrogen rate (EONR) for corn (Zea mays L.) is the high variability of soil nitrogen (N) supply due to environments, soil types, manure, and cropping histories. Portable instruments have been developed to measure leaf and canopy optical characteristics for determining plant N status. The objectives of this field study were to: (1) evaluate leaf and canopy optical properties including transmittance, reflectance, and fluorescence as indicators of corn N status with soil types, developmental stages, and N‐application rates, (2) compare the efficiency of two commercial radiometers that are designed to measure canopy reflectance, and (3) assess the constraints of these crop‐based indicators as a possible guide for real‐time N sidedressing in corn. Field experiments with different levels of N, soil types, and corn hybrids were conducted at three sites in Ottawa, ON, Canada, in 2004 and 2005. Leaf chlorophyll concentrations (SPAD chlorophyll meter), chlorophyll fluorescence (OS‐30), leaf area, and canopy reflectance (NDVI measured by CropScan and GreenSeeker radiometers) were simultaneously measured at several growth stages, while grain yield was determined at harvest. Our results show that canopy reflectance (NDVI) displayed similar efficiency as an indicator of N status on both soil types and corn hybrids in the two consecutive years. The chlorophyll readings often differentiated N‐deficient from N‐sufficient plots and therefore were a promising indicator for predicting corn N requirements. The fluorometer device evaluated in this study was unable to characterize corn N status.     

Humoral immune response of water buffalo monitored with three different antigens of Toxocara vitulorum

Humoral immune response of water buffalo naturally infected with Toxocara vitulorum was monitored using three different antigens of this parasite in serum and colostrum of buffalo cows and calves. Soluble extract (Ex) and excretory/secretory (ES) larval antigens and perienteric fluid antigen (Pe) of adult T. vitulorum were used to measure the antibody levels by an indirect ELISA. Serum of 7-12 buffalo cows for the first 365 days and colostrum of the same number of buffalo cows for the first 60 days of parturition, and serum of 8-10 buffalo calves for the first 365 days after birth were assayed. The ELISA detected antibodies against all three T. vitulorum antigens in the colostrum and serum of 100% of buffalo cows and calves examined. The highest antibody levels against Ex, ES and Pe antigens were detected in the buffalo cow sera during the perinatal period and were maintained at high levels through 300 days after parturition. On the other hand, colostrum antibody concentrations of all three antigens were highest on the first day post-parturition, but decreased sharply during the first 15 days. Concomitantly to the monitoring of immune response, the parasitic status of the calves was also evaluated. In calves, antibodies passively acquired were at the highest concentrations 24 h after birth and remained at high levels until 45 days coincidentally with the peak of T. vitulorum infection. The rejection of the worms by the calves occurred simultaneously with the decline of antibody levels, which reached their lowest levels between 76 and 150 days. Thereafter, probably because of the presence of adults/larvae stimulation, the calves acquired active immunity and the antibodies started to increase slightly in the serum and plateaued between the days 211 and 365. All three antigens were detected by the serum antibodies of buffalo calves; however, the concentration of anti-Pe antibody was higher than anti-EX and anti-ES, particularly after 90 days of age. By conclusion, the buffalo cows develop immunity and keep high levels of antibodies against T. vitulorum-Ex, ES and Pe antigens and these antibodies are transferred to their calves through the colostrum. This passively acquired immunity does not protect the calves against the acquisition of the infection, but these antibodies, passively or actively acquired, may have an important role during worm rejection by the calves and prevention of intestinal reinfection.