Delayed harvest of reed canary grass translocates more nutrients in rhizomes

Abstract

Two field experiments, one in large plots and the other in small framed plots, were conducted in Umeå, northern Sweden. The objectives were (1) to examine the seasonal patterns of rhizome growth and nutrient dynamics of the energy crop reed canary grass (Phalaris arundinacea L.) in ley I and II, and (2) to evaluate the roles of soil type (mineral vs. organic), fertilisation level (0, 50, and 100 kg N ha^?1s), and season/harvest time (Oct-96, May-97, and Aug-97) on the rhizome growth and nutrient dynamics by means of a factorially designed experiment. The general pattern of rhizome growth was that biomass was low in June during initiation of shoot growth, but increased steadily during the growing season, reached a peak in late autumn, and remained high until next spring. The N and P accumulation in rhizomes followed a similar pattern. During ley years I and II, reed canary grass rhizome growth was less dependent on soil type, and more dependent on fertilisation and season, with fertilisation being the most important predictor of growth. The season/harvest time, followed by soil type, was the most important factor for both concentrations and therefore total uptake of N, P, and K in rhizomes. Soil type affected N content in rhizomes significantly, and also interacted with season and enhanced the effect on N, P, and K content in rhizomes. The seasonal dynamics of the nutrient content in rhizomes indicate a remobilisation of the nutrients from rhizomes to the regrowth of shoots and roots in spring and relocation/storage from aboveground shoots to rhizomes during late summer and autumn. The results of this study suggest that delaying the harvest to later than October would result in considerably more energy and nutrient resources being translocated from aboveground shoots to rhizomes for growth in the next season.     

Grazing by Steers at Different Sward Surface Heights on Extensive Pastures: A Study of Weight Gain and Fat Deposition

Live weight gain of steers grazing at three different target sward heights, Low (3-6 cm), Medium (6-10 cm) and High (>10 cm), together with carcass fat deposition, were studied during two grazing seasons. Sward height was measured with a sward stick. The grassland consisted of seminatural grazing areas mixed with previously cultivated areas. Animals grazed continuously with small adjustments in animal numbers (year 1) or pasture area (year 2) to maintain sward height within the target for each treatment. The recorded average sward heights were 4.7, 6.8 and 11.1 cm for pastures on treatments Low, Medium and High, respectively. The animals weighed approximately 440 kg at the start of the grazing season and went directly from pasture to slaughter at the end of the experiment. No differences between years were found and data from both years were thus pooled, giving a total of 50 steers of the Swedish Red and White breed in the data set. Over the whole grazing season, the average daily live weight gain of animals on treatment Low (0.43 kg day     

Performance,health and behaviour of organic growing-finishing pigs in two different housing systems with or without access to pasture

Abstract

The effects of two housing systems (deep litter and straw-flow), with and without access to pasture during the summer period, were studied in an organic growing-finishing pig herd. Performance, health, skin lesions and daytime pig activity were studied in 29 pens of 16 pigs (total of 464 pigs, in 4 batches). Data from 21 pens were used for comparisons of deep litter and straw-flow and data from 16 pens for comparisons of access/no access to pasture. Pigs in the deep litter system had a lower carcass meat percentage (56.6% vs. 57.3%) and more locomotion problems (4.4% vs. 0%) than pigs in the straw-flow system. No difference in daytime pig activity was detected between the two housing systems. Under moderate temperatures, pigs with access to pasture and fed a commercial organic feed inside the building were not more active during daytime behaviour studies (7.30?h–16.30?h) than pigs without access to pasture. However, at 17 weeks of age the pigs with pasture access spent 21% of their time on pasture, less time inside the pig house (20% vs. 33%) and less time on the outside concrete area (4% vs. 12%) than the pigs without pasture. No difference in performance was detected between pigs with and pigs without access to pasture.     

Pup mortality in laboratory mice – infanticide or not?

Background

Despite being the most commonly used mammal in biomedical research, problems with perinatal mortality in mice have received little attention and the causes of pup death are still poorly known. Females are often housed alone with their litters and since the lost pups are generally eaten, it is commonly assumed that the mother has killed them. However, more detailed observations than have been reported previously in the literature are required to establish if the cause of death is infanticide. Litter loss can only be prevented efficiently after underlying causes have been carefully investigated and interpreted. The aim of this study was to investigate if females actively kill their pups by observing the behaviour of females and pups in litters that later were lost. We used video recordings of females that lost their entire litter to observe females in detail from parturition until the pups died. In total, 10 C57BL/6 females (wildtype and the knockouts Hfe^−/− and β2m^−/−) were studied, housed in Makrolon II cages with or without access to a small amount of nesting material.

Results

Three of the females had pups that were never seen moving, and another three females had one or two pups that never moved, indicating that some pups were most likely still-born. In five females with live-born pups, detailed observations from the time when a pup was last seen moving until it died were possible to carry out. We observed females eating dead offspring and interacting with both moving and dead pups. However, we never observed a pup stop moving when manipulated by the female, nor were any wounds seen in the pups. Hence, we found no evidence of infanticide when studying females that had lost their entire litter.

Conclusion

These results suggest that other causes than infanticide plays a major role in mouse pup death, and stress the need for more systematic and careful investigations of the causality of litter loss.     

Restoration fire and wood-inhabiting fungi in a Swedish Pinus sylvestris forest

A growing awareness of the negative consequences of efficient fire prevention in boreal Fennoscandia has resulted in an increasing use of fire as a restoration method. The primary purpose of restoration fire is to recreate features of natural forests that have been lost during long periods of fire suppression. We used the occurrence of fruiting bodies from wood-inhabiting fungi to assess the conservation value of and gain ecological information about restoration fire in a Pinus sylvestris dominated forest. The general pattern for the majority of the species was a drastic decline the first two years after the restoration fire. However, our results clearly demonstrate that most of the species that declined the first years after the fire rebounded after four years and were frequently found on charred wood. Species that increased after the fire and often occurred on charred logs were: Antrodia sinuosa, Botryobasidium obtusisporum, Galzinia incrustans, Phlebia subserialis and Tomentella spp. In addition, three threatened, red-listed and fire-favored species were also found on heavily charred logs: Antrodia primaeva, Dichomitus squalens and Gloeophyllum carbonarium. Our results indicate that fire disturbance creates a unique type of dead wood important for fungal species richness. The results also support the use of restoration fires in maintaining forest biodiversity.     

Hunting reduces recruitment of primate-dispersed trees in Amazonian Peru

Hunting with firearms decimates primates of large and medium body size (>2 kg) that disperse the seeds of large-seeded trees. In continuous, un-fragmented forests of southeastern Peru regularly hunted with firearms for 30-40 years, large primates are extirpated and medium-sized (medium) primates are reduced 61% compared with protected forests. At hunted sites seedlings and small juveniles (<1 m height) of trees dispersed by primates heavier than 2 kg are reduced 46%, a loss of one species m⁻², and abiotically-dispersed plants are 284% more common, adding eight individuals m⁻², compared with protected forests. Here we provide evidence consistent with the long-held prediction that commercial hunting changes plant communities. We show that the composition of seedling and small juvenile tree communities that ultimately regenerate future forests differs markedly in forests hunted with firearms compared with protected forests. This opens the possibility of shifts in tree species composition, even in hunted forests that are not logged or fragmented, towards forests dominated by trees dispersed by wind or non-game animals.     

Confirmation of a Campylobacteriosis Outbreak Associated with Chicken Liver Pâté Using PFGE and WGS

In May 2012, an outbreak of campylobacteriosis occurred in southern Sweden at a wedding reception affecting 44 persons. A total of 17 cases were notified (13 were culture positive for Campylobacter spp.). Epidemiological investigation suspected chicken liver pâté as the source of infection. The liver pâté had been deliberately undercooked, lightly fried to keep the right texture and mixed with spices. Campylobacter isolates from six cases as well as three Campylobacter isolates from chicken flocks previously raised by the producer delivering the liver were subtyped using pulsed‐field gel electrophoresis and whole‐genome sequencing. Indistinguishable PFGE profiles were identified among five human and one chicken C. jejuni isolates as well among the two C. coli isolates, one from a human case and one from a chicken. WGS supported the PFGE findings; the six C. jejuni isolates belonged to one cluster. All these six isolates were of MLST type ST 50 (ST‐CC 21). This study highlights the importance of a combination of strict biosecurity at the flock‐level as well as adequate cooking of chicken liver to prevent transmission of Campylobacter to humans.     

Intestinal macromolecular transmission in underprivileged and unaffected newborn pigs: implication for survival of underprivileged pigs.

Passive immunisation of the newborn pig depends upon intestinal macromolecular transmission to the blood, which ceases within 18 to 36 hours after birth in fed pigs. Macromolecular transmission in newborn, unsuckled pigs was tested by gavage feeding bovine serum albumin and fluorescein isothiocyanate-labelled dextran (molecular weight 70 kDa) together with sow colostrum. Serum levels measured four hours after feeding showed that underweight pigs under 1.0 kg, both apparently normal and weak, had a greater capacity for transmission than did apparently normal pigs over 1.0 kg (unaffected). Weak pigs 1.0 kg, or more, had a transmission equivalent to that of unaffected pigs, indicating that they may be otherwise normal animals affected by birth. Splayleg pigs and their clinically unaffected littermates also showed a greater capacity for transmission than unaffected pigs; splayleg apparently involves the entire litter, although the expression of the syndrome varies. The capacity for transmission in the unaffected pig increased with litter size and decreased with an increase in weight and age after birth. In addition, it was shown that transmission was greater in pigs with higher glucose, insulin and alpha-fetoprotein concentrations and lower haemoglobin, cortisol and alpha 2-macroglobulin f concentrations at birth. It was concluded that immature pigs have a greater capacity for intestinal macromolecular transmission at birth than unaffected pigs over 1.0 kg. Since the capacity for macromolecular transmission decreases with age, the probability of their survival depends very much on the husbandry practices in the herd.