John Koolaard

A proposed taxonomy of anaerobic fungi (class neocallimastigomycetes) suitable for large-scale sequence-based community structure analysis.

Anaerobic fungi are key players in the breakdown of fibrous plant material in the rumen, but not much is known about the composition and stability of fungal communities in ruminants. We analyzed anaerobic fungi in 53 rumen samples from farmed sheep (4 different flocks), cattle, and deer feeding on a variety of diets. Denaturing gradient gel electrophoresis fingerprinting of the internal transcribed spacer 1 (ITS1) region of the rrn operon revealed a high diversity of anaerobic fungal phylotypes across all samples. Clone libraries of the ITS1 region were constructed from DNA from 11 rumen samples that had distinctly different fungal communities. A total of 417 new sequences were generated to expand the number and diversity of ITS1 sequences available. Major phylogenetic groups of anaerobic fungi in New Zealand ruminants belonged to the genera Piromyces, Neocallimastix, Caecomyces and Orpinomyces. In addition, sequences forming four novel clades were obtained, which may represent so far undetected genera or species of anaerobic fungi. We propose a revised phylogeny and pragmatic taxonomy for anaerobic fungi, which was tested and proved suitable for analysis of datasets stemming from high-throughput next-generation sequencing methods. Comparing our revised taxonomy to the taxonomic assignment of sequences deposited in the GenBank database, we believe that >29% of ITS1 sequences derived from anaerobic fungal isolates or clones are misnamed at the genus level.

Parenteral administration of twin-bearing ewes with L-arginine enhances the birth weight and brown fat stores in sheep

The objective of this study was to evaluate the effects of parenteral administration of L-arginine (Arg) to well-fed twin-bearing ewes from day (d) 100 of pregnancy to birth on fetal growth, body composition and neonatal behavior. Ewes received an i.v. bolus of either 345 μmol Arg-HCl/kg bodyweight or saline solution (control) 3 times a day. At d 140 of pregnancy, Arg-supplemented and control ewes were euthanized and fetal weight and fetal organ weight recorded, and maternal and fetal plasma concentrations of amino acids, hormones and metabolites analyzed. A subset of ewes was allowed to lamb and birth weight, body dimensions and behavior of the lambs in the first 2 hours(h) following birth recorded and blood samples collected. At d 140 of pregnancy, fetal weight internal organ weights were unaffected by treatment with the exception of brown fat stores which were increased by 16% in fetuses from Arg-supplemented ewes relative to controls (P < 0.05). At birth, there was an interaction (P = 0.06) between treatment and sex for birth weight of the lamb. The ewe lambs from Arg-supplemented ewes were 12% (P < 0.05) heavier at birth compared with controls whereas birth weight of male lambs did not differ. These results indicate that maternal Arg supplementation enhanced brown fat stores in the fetus and countered some effect of fetal growth restriction due to litter size in female lambs. Increasing birth weight of female lambs and enhancing brown fat stores of all lambs may have important implications for lamb survival and postnatal growth.

Selenium-Enriched Foods Are More Effective at Increasing Glutathione Peroxidase (GPx) Activity Compared with Selenomethionine: A Meta-Analysis

Selenium may play a beneficial role in multi-factorial illnesses with genetic and environmental linkages via epigenetic regulation in part via glutathione peroxidase (GPx) activity. A meta-analysis was undertaken to quantify the effects of dietary selenium supplementation on the activity of overall GPx activity in different tissues and animal species and to compare the effectiveness of different forms of dietary selenium. GPx activity response was affected by both the dose and form of selenium (p < 0.001). There were differences between tissues on the effects of selenium supplementation on GPx activity (p < 0.001); however, there was no evidence in the data of differences between animal species (p = 0.95). The interactions between dose and tissue, animal species and form were significant (p < 0.001). Tissues particularly sensitive to changes in selenium supply include red blood cells, kidney and muscle. The meta-analysis identified that for animal species selenium-enriched foods were more effective than selenomethionine at increasing GPx activity.

Plant vigour at establishment and following defoliation are both associated with responses to drought in perennial ryegrass ( Lolium perenne L.)

Highlight text We have developed a new methodology to assess individual perennial ryegrass plant performance under moisture stress and identified QTLs associated with improved performance during drought in this important forage species.

Methane emissions from lactating and non-lactating dairy cows and growing cattle fed fresh pasture

Currently, a fixed methane (CH4) emission factor is used for calculating total CH4 emissions from cattle in the national greenhouse gas inventory of New Zealand, independent of diet composition, cattle class (beef, dairy) or physiological state (growing, lactating, non-lactating). The objectives of this study were to determine CH4 emissions from lactating and non-lactating dairy cows (118 dairy cows; 81 lactating and 37 non-lactating, over 10 periods) and growing dairy heifers (12 measured twice) fed 100% fresh pasture forage in respiration chambers, which in combination with the published data of beef cattle (36 measured twice) fed fresh pasture were used to determine the relationship between CH4 emissions and dry matter intake (DMI), feed quality, cattle class (dairy vs beef) and physiological state (lactating, non-lactating and growing). Before regression analysis the dominant variables (DMI, CH4) needed to be transformed using natural logarithms (Ln) to make the variation in CH4 emissions more homogeneous across the range of data (i.e. stabilise the variance). Over all periods, average DMI ranged from 3.1 to 13.9 kg/day, average CH4 production from 64 to 325 g/day and average CH4 yield from 21.4 to 26.5 g/kg DMI. The DMI alone explained 90.8% of the variation in CH4 production (LnCH4 (g/day) = 3.250 + 0.9487 × LnDMI). Regression was improved to a minor extent (<3%, with associated increased prediction error) by including physiological status, cattle class or dietary composition in the model, in addition to LnDMI, on LnCH4 production. In conclusion, DMI alone was the strongest predictor for CH4 emissions from cattle fed fresh pasture with minor but irrelevant improvements in the prediction when considering pasture quality, cattle class or physiological status.

Fungicide control of head smut (Sporisorium reilianum) of sweetcorn (Zea mays)

Abstract A field trial was carried out to compare the efficacy of the fungicides carboxin + thiram (Vitafio®), carbendazim (Prolific®), tebuconazole (Raxil®), propiconazole (Tilt®), fiutriafol + imazalil sulphate (Vincit™), and azoxystrobin (Amistar®) as seed applications for the control of head smut of sweetcorn (Zea mays), caused by the fungus Sporisporium reilianum (Sphacelotheca reiliana). The trial was carried out in the Poverty Bay region of New Zealand in a field that had a previous history of head smut. Carbendazim, fiutriafol + imazalil sulphate, propiconazole, and azoxystrobin seed treatments resulted in significantly greater plant numbers and increased early plant growth compared with the untreated experimental control, carboxin + thiram, and tebuconazole treatments. Plots in the control and carboxin + thiram treatments had a relatively high number of stunted plants (<10 cm) 1 month after sowing (7.6% and 14.9% respectively). Carbendazim, tebuconazole, propiconazole, fiutriafol + imazalil sulphate, and azoxystrobin seed treatments all produced low numbers of stunted plants (0.4–3.1%). Of the plants in the untreated control plots, an average of 8.7% were infected with head smut at harvest maturity. Seed treatment with carboxin + thiram didnotreduce numbers of smutted plants compared with the untreated control. All other fungicides reduced the proportion of diseased plants. The most effective were propiconazole and fiutriafol + imazalil sulphate, which respectively gave 2.3% and 2.4% plants infected with head smut. Carbendazim, tebuconazole, and azoxystrobin were slightly less effective reducing infection to 5–6%. Fiutriafol + imazalil sulphate and propiconazole both offer alternatives to carboxin + thiram for control of head smut of sweetcorn.

The effect of maternal arginine supplementation on the development of the thermogenic program in the ovine fetus

Brown adipose tissue (BAT) is a specialised fat store that is metabolised by the newborn lamb to ensure effective adaptation to the cold challenge of the extra-uterine environment. Increasing BAT reserves therefore has the potential to increase neonatal thermogenesis and survival. It is established that arginine supplementation can increase fetal BAT stores but the biological mechanisms involved are unclear. The objective of this study was to test the hypothesis that increased fetal BAT stores resulting from maternal arginine supplementation is mediated by activation of the thermogenic program. Brown adipose tissue was collected from fetuses of ewes supplemented with arginine from 100 to 140 days of gestation. Increased peri-renal fat stores in fetuses from arginine-supplemented ewes was associated with an increase in uncoupling protein 1 (UCP-1) and PRD1-BF-1-RIZ1 homologous domain containing protein-16 expression, but not proliferator-activated receptor gamma or proliferator-activated receptor gamma-co-activator-1α in BAT. The activity of UCP-1 is regulated by hormones including cortisol and thyroid hormones. Cortisol level in fetuses from supplemented sheep was 68% greater than those from control ewes, indicating that cortisol may control upregulation of UCP-1 expression in the ovine neonate. The DNA and RNA concentration in BAT of both groups suggest that increased peri-renal fat stores is not associated with an increase in cell number or number of ribosomes, but rather an increase in the size of individual fat cells. Collectively, these results indicate that maternal arginine supplementation during mid to late gestation improved the thermoregulatory ability of lambs and this could potentially increase their survival in early life.

Extending the Collection Duration of Breath Samples for Enteric Methane Emission Estimation Using the SF6 Tracer Technique

Simple Summary Extended sample collection for the SF6 tracer technique is desirable for extensive grazing systems. Breath samples from eight cows were collected while lucerne silage was fed to achieve fixed intakes among the cows. Samples were collected over a 10-day period, using either apparatuses used in New Zealand (NZL) or Argentina (ARG), and either daily, over two consecutive 5-day periods or over a 10-day period (in duplicate). The NZL system had a greater sampling success and more consistent CH4 emission estimates than the ARG system, with no differences in mean emissions among sample collection periods. This study showed that extended sample collection is feasible, but definitive evaluation under grazing situation is required before a decision on recommendation can be made. Abstract The daily sample collection protocol of the sulphur hexafluoride (SF6) tracer technique for the estimation of methane (CH4) emissions from ruminants may not be practical under extensive grazing systems. Here, under controlled conditions, we evaluated extended periods of sampling as an alternative to daily sample collections. Eight rumen-fistulated cows were housed and fed lucerne silage to achieve common daily feed intakes of 6.4 kg dry matter per cow. Following SF6 permeation tube dosing, eight sampling lines were fitted to the breath collection harness, so that a common gas mix was available to each line. Half of the lines collected samples into PVC yokes using a modified capillary system as commonly used in New Zealand (NZL), and half collected samples into stainless steel cylinders using a ball-bearing flow restrictor as used in Argentina (ARG), all within a 10-day time frame, either daily, across two consecutive 5-day periods or across one 10-day period (in duplicate). The NZL system had greater sampling success (97.3 vs. 79.5%) and yielded more consistent CH4 emission estimates than the ARG system. Emission estimates from NZL daily, NZL 5-day and NZL 10-day samplings were 114, 110 and 111 g d−1, respectively. Extended sample collection protocol may be feasible, but definitive evaluation of this alternative as well as sample collection systems is required under grazing situations before a decision on recommendation can be made.

Genetic analysis of sweetness and textural attributes in winter squash (Cucurbita maxima)

Abstract Quantitative genetics of chemical and textural attributes of quality of winter squash (Cucurbita maxima) were studied using the F1, F2, and backcrosses of the two crosses ‘Scarlet Warren’ × ‘CF2’ and ‘Scarlet Warren’ × ‘CF4’. The 3‐parameter additive‐dominance model adequately explained the variation among generation means of ‘Scarlet Warren’ × ‘CF2’ for dry matter (DM), alcohol‐insoluble solids, sucrose, glucose, fructose, soluble pectin, springiness, and adhesiveness but failed with total pectin, fracture hardness, and cohesiveness. Among generation means of ‘Scarlet Warren’ × ‘CF4’, the model explained the variation in all attributes except DM and springiness. Additive gene effects were negative for DM, alcohol‐insoluble solids, sucrose, soluble pectin, and adhesiveness but positive for glucose, fructose, total pectin, and springiness. Dominance gene effects were negative for alcohol‐insoluble solids and total pectin but positive for all three sugars, soluble pectin, springiness, and adhesiveness. Low heritability for most attributes other than sucrose indicated that environmental impacts (attributed to different growing climates for the two sites used for this study) were larger than genetic effects. Thus, breeding to produce sweeter squash is feasible, but breeding for textural improvement would seem to be problematic because the environment has an overriding effect on textural attributes.

cAMP Signaling Regulates Synchronised Growth of Symbiotic Epichloë Fungi with the Host Grass Lolium perenne

The seed-transmitted fungal symbiont, Epichloë festucae, colonizes grasses by infecting host tissues as they form on the shoot apical meristem (SAM) of the seedling. How this fungus accommodates the complexities of plant development to successfully colonize the leaves and inflorescences is unclear. Since adenosine 3′, 5′-cyclic monophosphate (cAMP)-dependent signaling is often essential for host colonization by fungal pathogens, we disrupted the cAMP cascade by insertional mutagenesis of the E. festucae adenylate cyclase gene (acyA). Consistent with deletions of this gene in other fungi, acyA mutants had a slow radial growth rate in culture, and hyphae were convoluted and hyper-branched suggesting that fungal apical dominance had been disrupted. Nitro blue tetrazolium (NBT) staining of hyphae showed that cAMP disruption mutants were impaired in their ability to synthesize superoxide, indicating that cAMP signaling regulates accumulation of reactive oxygen species (ROS). Despite significant defects in hyphal growth and ROS production, E. festucae ΔacyA mutants were infectious and capable of forming symbiotic associations with grasses. Plants infected with E. festucae ΔacyA were marginally less robust than the wild-type (WT), however hyphae were hyper-branched, and leaf tissues heavily colonized, indicating that the tight regulation of hyphal growth normally observed in maturing leaves requires functional cAMP signaling.