Metabolic and endocrine profiles and reproductive parameters in dairy cows under grazing conditions: effect of polymorphisms in somatotropic axis genes

<p>Abstract</p> <p>Background</p> <p>The present study hypothesized that GH-AluI and IGF-I-SnabI polymorphisms do change the metabolic/endocrine profiles in Holstein cows during the transition period, which in turn are associated with productive and reproductive parameters.</p> <p>Methods</p> <p>Holstein cows (Farm 1, primiparous cows, n = 110, and Farm 2, multiparous cows, n = 76) under grazing conditions were selected and GH and IGF-I genotypes were determined. Blood samples for metabolic/endocrine determinations were taken during the transition period and early lactation in both farms. Data was analyzed by farm using a repeated measures analyses including GH and IGF-I genotypes, days and interactions as fixed effects, sire and cow as random effects and calving date as covariate.</p> <p>Results and Discussion</p> <p>Frequencies of GH and IGF-I alleles were L:0.84, V:0.16 and A:0.60, B:0.40, respectively. The GH genotype was not associated with productive or reproductive variables, but interaction with days affected FCM yield in multiparous (farm 2) cows (LL yielded more than LV cows) in early lactation. The GH genotype affected NEFA and IGF-I concentrations in farm 1 (LV had higher NEFA and lower IGF-I than LL cows) suggesting a better energy status of LL cows.</p> <p>There was no effect of IGF-I genotype on productive variables, but a trend was found for FCM in farm 2 (AB cows yielded more than AA cows). IGF-I genotype affected calving first service interval in farm 1, and the interaction with days tended to affect FCM yield (AB cows had a shorter interval and yielded more FCM than BB cows). IGF-I genotype affected BHB, NEFA, and insulin concentrations in farm 1: primiparous BB cows had lower NEFA and BHB and higher insulin concentrations. In farm 2, there was no effect of IGF-I genotype, but there was an interaction with days on IGF-I concentration, suggesting a greater uncoupling somatropic axis in AB and BB than AA cows, being in accordance with greater FCM yield in AB cows.</p> <p>Conclusion</p> <p>The GH and IGF-I genotypes had no substantial effect on productive parameters, although IGF-I genotype affected calving-first service interval in primiparous cows. Besides, these genotypes may modify the endocrine/metabolic profiles of the transition dairy cow under grazing conditions.</p

18O Fractionation in the coralline aragonite of Porites lobata: Implications in oceanic paleothermometry studies

This study is fundamentally focused on a simple, but relatively unpondered problem: the coral δ18O temperature sensitivity (dδ/dT). Previous paleotemperature studies of corals have involved the use of either: 1) the calcite’s δ18O temperature sensitivity for mollusks (Epstein et al., 1953) or 2) the slope value (Δδ/ΔT) obtained by comparing annual temperature extrema versus annual δ18O extrema in the annual growth bands of coral skeletons. Because both perspectives involve the use of different values for the thermal sensitivity of the coral skeleton, significant discrepancies may be obtained while reconstructing oceanic paleotemperatures. In order to solve this problem, a field calibration was conducted by comparing the δ18O composition of coral skeletons of Porites lobata with sea surface temperature (SST). A paleotemperature equation for P. lobata was determined by comparing the sclerochronologicaly determined monthly skeletal δ18O values with monthly SST values for the Costa Rican coast. Additionally, when δw effects were considered in the coral skeletons, it was found that Porites yields a temperature dependent 18O isotopic fractionation between 0.222 and 0.235‰/ºC. This study reveals that the thermal sensitivity of the coralline aragonite is slightly larger than that for mollusk’s calcite. Therefore, future oceanic paleotemperature applications that involve corals should avoid the use of the thermal sensitivity of the δ18O of biogenic calcite, as has been done in the past. The use of the slope value proposed here may also eliminate the common problem of the seasonal ΔTºC not matching the Δ(δc-δw) observed in the coral skeletons

Stable isotope paleoenvironmental record of a coral from Cabo Pulmo, entrance to the Gulf of california, mexico

A 17-year-long record of δ18O and δ13C from a Cabo Pulmo coral (Pavona gigantea) was analyzed. Although the coral δ18O signal is mainly temperature controlled (~70%), the seasonal arrival of surface water masses to the Gulf of California produces an isotopic effect in the opposite direction to that produced by temperature. During summer and fall, the arrival of Equatorial water effectively reduces the annual range in the δ18O of the coral skeletons by increasing the δ18O value of water, even though this occurs during the rainy season. The incursion of Equatorial water masses to the entrance of the Gulf of California during El Niño years is so strong that even during the strongest ENSO years there is no important isotopic shift in the skeleton, even though temperature records show significant positive temperature anomaly in the region. The same effect occurs for La Niña years, but in the opposite direction. By deconvoluting the temperature signal from the isotopic record, the seasonal interplay of the water masses from the California Current and the Costa Rica Coastal Current can be effectively deduced. Changes in the coral δ13C seem to coincide with periods of upwelling events in the gulf, with the highest value coinciding with the annual maximum in pigment concentration for the region

Calibration of Sr/Ca and Mg/Ca paleothermometers in coral Porites sp. from San Benedicto Island, Revillagigedo Archipelago, Mexico

A better understanding of the global climate system depends on our ability to expand the limited instrumental records of sea surface temperature (SST) of tropical regions. The Sr/Ca and Mg/Ca ratios contained in the growth bands of corals have proved to be an accurate tool to reconstruct SST variability. In this study we show the calibration obtained from the seasonal geochemical measurement of the Sr/Ca and Mg/Ca molar ratios in the skeleton of coral of the genus Porites from San Benedicto Island, in the Revillagigedo Archipelago, and SST. The geochemical ratios measured (precision ±0.2%, 2σ) showed a high seasonal covariation closely related to the region's SST. The calibration equation calculated for the Sr/Ca–SST relation (n = 52) was Sr/Ca (mmol mol–1) = 10.467 (±0.067) – 0.0524 (±0.003) × SST (r2 = 0.894), and for the Mg/Ca?SST relation it was Mg/Ca (mmol mol–1) = 1.550 (±0.095) + 0.0956 (±0.0043) × STT (r2 = 0.906). When comparing the SST time series reconstructed from the Sr/Ca and Mg/Ca ratios with the mean SST of a spatial grid of 2º × 2º (longitude × latitude) that comprises San Benedicto Island, we found a high concordance between both temperatures, showing the robustness of the procedure. A drawback of this method is that no unique calibration exists for the Sr/Ca–SST and Mg/Ca–SST relations, and the different calibrations published generate discrepancies of up to 8ºC in the calculated temperature, regardless of whether the thermal sensitivity (i.e., the slope of the paleotemperature equation) of corals is similar. We therefore concluded that the Sr/Ca and Mg/Ca paleothermometers are highly reliable in this region of the Pacific Ocean, provided that a specific equation exists for the area under study

Accumulation of Corg, Norg, Porg and BSi off the Magdalena, BCS, (México) during the past 26 kyr

The rates of accumulation of organic carbon, nitrogen and phosphorus (Corg, Norg, Porg), and of biogenic silica (BSi) were measured in sediment cores (GC31 and PC08) collected within the oxygen minimum zone of the Magdalena margin, off western Baja California Sur (Mexico). The rates of Corg, Norg and Porg accumulation were similar during marine isotopic stage 2 (MIS-2), the last glacial maximum (LGM) and the Late Holocene (LH, 3 kyr–Recent), whereas the rate of BSi accumulation was greater during LGM and MIS-2 than during LH. In general, primary productivity during the MIS-2 and the LGM was similar to that observed during LH. The N/P ratio during the MIS-2 and the LGM was equivalent to that found during LH, suggesting that N and P were not limiting factors. In fact, the BSi/C ratio was relatively high (intense upwelling) when the N/P ratio was relatively low, indicating similar levels of primary productivity during the MIS-2, the LGM and LH. The results show that the productivity levels during LH are characteristic, at least, of those that existed during the MIS-2. This indicates that the wind system has persisted since then, favouring an Ekman transport along the coast of California and Baja California, generating diatomdominated primary productivity

Growth of the hermatypic coral Montastraea cavernosa in the Veracruz Reef System

The hermatypic coral Montastraea cavernosa is one of the most important reef-builders in the Veracruz Reef System, an ecosystem that has developed in a highly turbid environment. Despite the ecological importance of this species, studies about its growth rate are scarce. This study therefore aims to present the annual growth rates of the scleractinian coral M. cavernosa for the period 1923–2001 in the southern Gulf of Mexico (SGM). Average extension rate was 2.9 ± 0.9 mm yr–1 (σ), which is slightly lower, although not significantly different, than previous records for this species from other reef settings. No correlation was found between sea surface temperature and extension rate, indicating that growth could be influenced by some other factor. We suggest that, as the coastal SGM is a turbid environment, the conditions for coral development are harsher than in other reef areas with pristine waters, and that this could negatively affect the coral's performance, reducing its growth rate.

Contribution of sedimentary resuspension to non-conservative fluxes of dissolved inorganic phosphorus in San Quintin Bay, Baja California: An experimental estimate

 Abiotic processes like sedimentary resuspension may contribute to non-conservative fluxes of dissolved inorganic phosphorus (DIP) in shallow systems like San Quintín Bay (SQB), because suspended particles may adsorb or desorb inorganic phosphate. The contribution of suspended sediments to DIP concentrations in SQB was determined in the laboratory through adsorption-desorption experiments with two types of sediments (fine sand and sandy silt), and different concentrations of suspended particles, the initial concentration of DIP and resuspension time. The zero equilibrium phosphate concentration (EPC0) was observed during the first step of the adsorption process (fast step), which occurred before 10 h. The EPC0 was exceeded after 24 h of resuspension, indicating the diffusion of P from the surface toward the interior of particles (slow step). Adsorption was the dominant process in the experiments, and the intensity of adsorption-desorption was emphasized with an increase in the amount of resuspended particles. From the comparison of the non-conservative fluxes of DIP estimated using the LOICZ model with those estimated with resuspension experiments, we conclude that adsorption may lead to an underestimation of ~20% of net heterotrophy in SQB calculated with the LOICZ model, as excess respiration leads to a net release of DIP to the water column, but adsorption by particles masks this net release