Association of fertility with group mating behavior in ewes.

It was hypothesized that values for fertility variables would vary with number of rams ewes mated with in a group mating management system. In Experiment 1, for adult ewes (n = 872) joined with rams for 35-38 days, 19.0 ± 2.2 %, 19.2 ± 3.5 %, 34.4 ± 1.3 % and 27.4 ± 3.3 % were marked by zero, one, two or three rams during the first 17 days, respectively. In general, as number of rams with which ewes mated increased, number of lambs born (NLB) increased, however, ovulation rate (OR) did not. In mated ewes, embryo survival (ES) increased (P < 0.05) as number of rams with which ewes mated increased. In Experiment 2, ewes that mated with zero or one ram had lesser concentrations of estradiol than ewes that mated with two or three rams when evaluated 30 h after initiation of the follicular phase. Following breeding on the subsequent estrus, number of fetuses at mid-gestation was less in ewes that had mated, in the previous estrus, with zero or one ram compared to two or three rams. In summary, ewes mating with a larger number of rams had greater values for the fertility variables that were evaluated compared with those mating with fewer rams. When ewes mated with fewer rams during the estrous period there were lesser concentrations of estradiol, potentially associated with the decreased ES.

Differences between ultrastructure and protein composition in straight hair fibres.

Mammalian hairs are internally patterned from both a morphological and proteomic perspective to exhibit specific functional traits, including curvature, which is important for coat structure affecting thermo-insulation. Most functional traits in mammalian coats are complex emergent phenomena associated with single-fibre properties that are themselves multi-variate and poorly understood. Here we compare hair curvature, ultrastructure, microstructure, protein composition and felting (a functional attribute) between fibres from natural straight-wool mutants of domestic sheep (felting lustre-mutant sheep), their wild-type relatives and also with a straight-haired semi-lustrous breed, English Leicester. Proteomic and structural results confirmed that the straight lustre mutant fibres had a normal cuticle and the same cortical protein and ultrastructural building blocks as wild-type fibres, but differed from equivalent fibres from wild-type relatives and English Leicester in layout and relative proportions. While curved wild-type fibres had bilaterally arranged orthocortex and paracortex, and English Leicester fibres had a scatter of paracortex on a background of orthocortex, lustre mutant fibres typically had a complete or partial ring of orthocortex surrounding a paracortex core, and sometimes a central orthocortex (similar to straight human and goat hairs). Lustre mutant fibres also had a reduced abundance of some high glycine-tyrosine proteins, normally associated with the orthocortex, with a possible relationship between the protein expression of the KAP8 and KAP16 protein families and fibre felting properties. We conclude that through control of the internal fibre patterning, multiple-solutions to hair curvature are possible, and variation may affect mechanical phenotype differently. Felting lustre mutant sheep will be a useful tool for discriminating cause and effect from non-causative correlation in mammalian fibre development.

Nitrate leaching losses during pasture renewal - Effects of treading, urine, forages and tillage.

Pasture renewal is a key component of intensive temperate grassland farming. This practice is performed to improve pasture yields, but it may increase nitrate (NO3-) leaching losses, which can impact on water quality. Farmers face many choices when renewing pasture, however, there is limited information to guide decisions to reduce leaching losses. An experiment was established to study how different management practices and grazing affect biomass production and NO3- leaching during pasture renewal on a heavy soil. Long-term pasture was either re-sown into ryegrass (Lolium perenne) in autumn (GG) or into forage rape (Brassica napus) followed by ryegrass in spring (GCG). Rape was established following ploughing or direct-drilling. Grazing was simulated in winter, whereby split plots ±urine (600 kg N ha-1) and ±treading were established. Nitrate concentrations at 1 m depth were measured with suction cups and drainage predicted using a crop model. Estimated NO3- leaching losses at 1 m depth ranged from 16 to 38 kg N ha-1, with little difference between GCG and GG. However, the risk of future leaching was much greater below GCG plots. At the end of the study, soil NO3- between 0.6 and 1 m ranged from 28 to 130 kg N ha-1 in GCG plots and 1-28 kg N ha-1 in the GG plots. Timing of leaching differed between renewal systems, reflecting the differences in plant N uptake and fallow period. Overall, there was no difference in dry matter production between the two systems. Treading resulted in greater compaction, especially in tilled plots and reduced NO3- leaching by c. 40% - this can be attributed to increased denitrification. Our study demonstrates the complex nature of management and environmental factors and their interaction during pasture renewal. We show that management practices affect the risk and timing of N leaching. Practical implications for farmers are discussed.

Variability of Escherichia coli Concentrations in Rivers during Base-Flow Conditions in New Zealand.

concentrations in rivers are known to vary considerably. Much research has focused on storm events and the relationships between fecal microbe concentrations and flows. However, there is still considerable variability in microbial concentrations during base-flow conditions, and little research has been conducted to understand this short-term variability in rivers. We investigated the variability of concentrations in base flows at the time scales of minutes, hours, and days and compared this to variability from laboratory replication of the measurement methods. This was conducted in three different-sized rivers in both summer and winter seasons. Estimates of variability were analyzed using the coefficient of variation (CV). The variability at the minute time scale was 17%, compared with the laboratory replication variability of 15%. The CV then increased to approximately 32 and 60% at the hourly and daily time scales, respectively. There is strong evidence that both time scale ( < 0.001) and river ( < 0.001) significantly affect the variation in concentrations. The concentrations were higher in summer than winter, with a marked effect in the smallest stream, where at one site the concentrations were >2000 most probable number (mpn) 100 mL in all summer samples. This variability of concentrations should be considered when interpreting the results from a one-off grab sample used to compare against water quality standards or for calibrating models.

Soil carbon sequestration potential of permanent pasture and continuous cropping soils in New Zealand.

Understanding soil organic carbon (SOC) sequestration is important to develop strategies to increase the SOC stock and, thereby, offset some of the increases in atmospheric carbon dioxide. Although the capacity of soils to store SOC in a stable form is commonly attributed to the fine (clay + fine silt) fraction, the properties of the fine fraction that determine the SOC stabilization capacity are poorly known. The aim of this study was to develop an improved model to estimate the SOC stabilization capacity of Allophanic (Andisols) and non-Allophanic topsoils (0-15 cm) and, as a case study, to apply the model to predict the sequestration potential of pastoral soils across New Zealand. A quantile (90th) regression model, based on the specific surface area and extractable aluminium (pyrophosphate) content of soils, provided the best prediction of the upper limit of fine fraction carbon (FFC) (i.e. the stabilization capacity), but with different coefficients for Allophanic and non-Allophanic soils. The carbon (C) saturation deficit was estimated as the difference between the stabilization capacity of individual soils and their current C concentration. For long-term pastures, the mean saturation deficit of Allophanic soils (20.3 mg C g-1 ) was greater than that of non-Allophanic soils (16.3 mg C g-1 ). The saturation deficit of cropped soils was 1.14-1.89 times that of pasture soils. The sequestration potential of pasture soils ranged from 10 t C ha-1 (Ultic soils) to 42 t C ha-1 (Melanic soils). Although meeting the estimated national soil C sequestration potential (124 Mt C) is unrealistic, improved management practices targeted to those soils with the greatest sequestration potential could contribute significantly to off-setting New Zealand's greenhouse gas emissions. As the first national-scale estimate of SOC sequestration potential that encompasses both Allophanic and non-Allophanic soils, this serves as an informative case study for the international community.