Research on the Effect of Plant Combination Types on the Shear Strength of the Root-soil Composite System of Alpine Grassland in the Source Region of the Yellow River北大核心CSCD

In this study,an alpine grassland in Henan County,Qinghai Province,in the source region of the Yellow River,was selected as the study area. The shear strength of root-soil composite system characteristics of 6 different plant combination types of grassland were explored by field investigation and sampling and indoor tests,which aimed to provide a theoretical basis for preventing and controlling soil erosion and shallow landslide caused by grassland degradation. The test results showed that the shear strength of root-soil composite system of 6 different combinations was a increasing trend with the decrease of altitude. Namely,the shear strength of the root-soil composite system of Stipa purpurea Griseb. + Kobresia pygmaea C. B. Clarke at the top of the sunny slope was 27.76 kPa and the value of Elymus nutans Griseb. at the bottom of the sunny slope was 37.53 kPa. The reasons why the shear strength of 6 kinds of combinations varied from large to small with the decrease of altitude were related to their density,moisture content,root content and dry weight of roots in the root-soil composite system samples. That is,the root content of composite system at the top,middle and bottom of the sunny slope were 6.2%,5.5% and 16.2%,respectively. The values at the top,middle and bottom of the shady slope were 8.0%,11.4% and 31.6%,respectively. © 2019 China Agricultural University. All rights reserved.     

The effect of tebuthiuron on the vegetation of the thorn Bushveld of the Northern Cape – a preliminary report

Abstract

Two formulations of tebuthiuron i.e. Graslan 20P and Graslan 40P are currently being evaluated in the Molopo area. Tebuthiuron was applied aerially at ten application rates, in combination with two application dates.

After only two seasons, the chemical has already shown a reasonable selectivity for the woody species. Of these, Acacia mellifera, A. reficiens and Grewia flava are very sensitive while A. erioloba and Dichrostachys cinérea are less sensitive and Boscia albitrunca seems almost resistant to the lower application rates (<1,0 kg a.i./ha).

The standing crop of grass on the treated plots increased by between 220 and 740 per cent. Changes in the total grass density and botanical composition can be ascribed to an increased density of Eragrostis lehmanniana.

At this stage of the trial, its selectivity in favour of the more desirable woody species, suggests that tebuthiuron shows great promise for controlling bush encroachment in the Northern Cape, although a final conclusion would only be possible 5 years after its application.     

Effect of prolonging the non‐productive period on the performance of moulted broiler breeders

1. The effect of prolonging the non‐productive period by offering cracked grain after food withdrawal on the performance of moulted broiler breeders was investigated.

2. Each increase in the non‐productive period resulted in a gradual decrease in egg production but a gradual increase in the percentages of hatching eggs, fertility and hatchability.

3. There were no significant differences between hens fed on cracked grain for 2 or 3 weeks for any of the performance characteristics, except fertility and hatchability. The best fertility and hatchability were observed in hens fed on cracked grain for 3 weeks.     

First Report on the Occurrence of ‘Helicobacter heilmannii’ in the Stomach of Rabbits

Gastric Helicobacter spp. have been described in a wide range of animal species, including dogs, cats, primates, swine, cattle and rodents. However, in lagomorphs--more specifically rabbits--gastric Helicobacter infections have never been reported. Biopsy specimens were collected from different stomach regions of 23 rabbits, including 10 pet rabbits, 10 industrial animals and 3 research animals. These were subjected to a PCR assay for the detection of Helicobacter DNA. Identification up to the species level was based on 16S rRNA sequence analysis and a recently developed multiplex PCR. Seven rabbits (four pet, one research animal and two industrial animals) tested positive in the Helicobacter genus-specific PCR in the stomach, with the corpus being predominantly positive. H. felis and H. salomonis, hitherto presumed to be naturally hosted by cats and dogs, were detected in three animals and one animal, respectively. One of these animals had been completely devoid of any form of contact with cats or dogs. A H. pullorum/H. rappini-like organism (96% 16S rDNA sequence similarity) was found in an industrially held rabbit. The helicobacters of the two remaining rabbits could not be identified up to the species level. To conclude, this is the first report on the occurrence of Helicobacter spp. in the stomach of rabbits. In view of the fact that H. felis and H. salomonis are put forward as having zoonotic potential, further research is necessary to investigate the implications of these findings not only for the rabbit but also for human health.     

Notes on the “wheaten” plumage phenotype of the domestic fowl

1. A study was made using a Light Sussex bantam hen to determine the allele present at the E locus. Conflicting results occurred on mating with different males suggesting the presence in one case of the dominant allele e^Wh and, in the other, of the recessive e^y.

2. Further examination of these apparently conflicting results suggests the possibility that there may be a single gene producing the wheaten phenotype which appears to be dominant if melanin restriction genes are present at other loci, or recessive by interaction with melanin intensifier genes. This gene may also require the presence of down‐diluting gene(s) to produce the wheaten phenotype.     

Some observations on the caecal micro‐flora of the chick during the first two weeks of life

1. Changes in the caecal flora of chicks aged from approximately 3 h to 14 d were studied.

2. Counts obtained by means of a conventional anaerobic plating method and a method for the stricter anaerobes remained comparable throughout but occasionally it was found that strains of anaerobic bacteria isolated from the predominant flora of 4‐ to 14‐d‐old birds could not be grown when tested by the conventional method.

3. During the 14‐d period approximately 100% of the organisms isolated on anaerobic plates utilised uric acid up to the third day but the incidence subsequently declined and in one case represented only 4% of the total flora.

4. The predominant uric acid‐utilising bacteria were Streptococcus faecalis and Escherichia coli up to 3 d of age and various types of anaerobic bacteria thereafter.

5. None of the isolates showed an absolute requirement for uric acid.     

Effects of avgard™ treatment on the microbiological flora of poultry carcases

1. The efficiency of the AvGard? (or Assur‐Rince? in the USA) trisodium phosphate poultry carcase decontamination process was evaluated during both manual and industrial trials against total aerobic mesophilic count (TAMC), thermotolerant coliforms, Pseudomonas, Enterobacteriaceae, Campylobacter, Listeria monocytogenes and Salmonella.

2. The TSP treatment proved to have significant effects on the bacterial decontamination of poultry neck skin, lowering the contamination by a factor of about 10 for TAMC and of 100 for Coliform and Pseudomonas.

3. Numeration of Salmonella with an innovative miniaturised most probable number method has proved that the effect upon these micro‐organisms was also close to 2 log₁₀ reduction.

4. The effect of TSP treatment on the ecological balance of psychrotrophic bacterial flora was also investigated to study the origin of the shelf‐life flora of treated carcases (Pseudomonas being reduced to the limit of detection) and to ascertain whether L. monocytogenes might gain a competitive advantage. In fact AvGard? reduced the number of L. monocytogenes on poultry carcases.

5. As a consequence of the virtual elimination of the Pseudomonas usually present, Brochothrix thermosphacta became the main species responsible for putrefaction.

6. Because the growth rate of Brochothrix thermosphacta was greater than that of L. monocytogenes at refrigeration temperature, it was considered that putrefaction would occur before the emergence of large numbers of L. monocytogenes.     

The influence of the tracer injection–acquisition interval on the distribution of 99mTc-ECD in the brain of laboratory cats

Single-photon emission computed tomography (SPECT) can be used to study the regional distribution of the cerebral blood flow in the feline brain without interference of anesthetics. When the tracer, ^99mtechnetium-ethyl cysteinate dimer (^99mTc-ECD), is injected in the awake animal, the acquisition can be performed afterward under general anesthesia, whereas the tracer distribution still represents the regional cerebral blood flow (rCBF) in the awake animal. The aim of this study was to look at the in vivo stability of ^99mTc-ECD in the feline brain. For this purpose, 6 cats (n = 6) were used, and 3 serial acquisitions were performed starting at 40 (T40), 60 (T60), and 85 (T85) minutes after tracer injection. Total counts and perfusion indices (PIs), normalized to the total brain and to the cerebellum, were calculated. When T85 was compared with T40, total counts decreased, depending on the brain region, with 29% (left thalamus) to 51% (bulbus olfactorius). These regional differences in tracer clearance resulted in significantly altered PIs at T85 as compared with T40. This study shows that ^99mTc-ECD SPECT can be used in cats for studying the rCBF and that the clearance of ^99mTc-ECD in the feline brain is region dependent. As a result, the acquisition should be started between 40 and 60 minutes after tracer injection.     

Studies on the avian shell gland during egg formation: The effect of acetazol‐amide on the transfer of ions to the albumen 1

1. Twenty‐five laying hens were fed on a diet containing 100 mg acetazolamide/kg in order to determine the effects of a decrease in the activity of carbonic anhydrase on the transfer of minerals to the egg albumen.

2. Treatment with acetazolamide decreased the rate of shell formation by 44%; reduced the concentrations of water and Na+ in the albumen at the beginning of the plumping stage but increased the accumulation of water during plumping; increased the concentration of Cl‐ in the albumen after the 6‐h stage without any appreciable change in K+ and Ca²⁺ concentrations.

3. The computed relationships between the concentrations of different ions also showed that the transfer of water and Na+ were linked during egg formation, that a water‐independent, acetazolamide‐sensitive reabsorption of Na+ occurred after the 10‐h stage and that Na+ and Cl‐moved simultaneously up to 14 h but with the ratio of Cl‐ to Na+ three times higher in the treated group.

4. It is concluded that acetazolamide impairs the transfer of Na+ and Cl‐ between the albumen and the extracellular fluid and that secretion of Ca²⁺ into the uterine lumen seems to depend on Na+ and Cl‐ reabsorption.     

Effect of Supplement of Lysine on the Nutrients Arriving at the Abomasum of Polled Dorset譙mall-tail Han Lambs

将8只40日龄安装永久性皱胃瘘管的无角陶赛特与小尾寒羊杂交F1代母羔(平均体重为8.90 kg±0.38 kg)根据体重分为2组,每组4只,在60~80、81~120和121~240日龄分别饲喂日粮1、2和3,并分别添喂1.2%、0.8%和0.4%的赖氨酸,以研究添喂赖氨酸对到达羔羊皱胃营养物质的影响。结果表明,与对照组相比,在日粮1、2和3中添喂不同水平的赖氨酸,使羔羊到达皱胃的干物质分别增加了7.01%(P＞0.05)、11.59%(P＜0.01)和10.65%(P＜0.05),有机物分别增加了8.48%(P＞0.05)、13.01%(P＜0.05)和12.14%(P＜0.01),粗蛋白质分别增加了11.12%(P＞0.05)、21.73%(P＜0.01)和12.44%(P＜0.05),微生物蛋白分别增加了13.46%(P＜0.05)、26.85%(P＜0.01)和15.08%(P＜0.05),总氨基酸分别增加了39.22%(P＜0.01)、35.52%(P＜0.01)和28.27%(P＜0.05),总必需氨基酸分别增加了49.21%(P＜0.01)、34.40%(P＜0.01)和28.11%(P＜0.05),赖氨酸分别增加43.77%(P＜0.01)、37.25%(P＜0.01)和34.38%(P＜0.05)。在对照组和试验组中,到达皱胃的赖氨酸主要为结合赖氨酸,而游离赖氨酸一般低于总赖氨酸量的1%。添喂赖氨酸使羔羊的干物质自由采食量分别比对照组提高了12.57%(P＞0.05)、19.38%(P＜0.01)和16.29%(P＜0.01),前胃干物质消化量分别增加了20.81%(P＞0.05)、35.64%(P＜0.01)和19.97%(P＜0.01),日增重分别提高了17.34%(P＜0.05)、21.30 %(P＜0.01)和17.76%(P＜0.05)。因此,给60~240日龄羔羊添喂赖氨酸可增加到达皱胃的营养物质的量和前胃有机物的消化量,从而增加羔羊的营养供应。     

Effects of 2 training methods on stress-related behaviors of the dog (Canis familiaris) and on the dog–owner relationship

Instrumental learning plays an important role in dog–human interactions. The recent demand for pet dog training has resulted in the development of various training methods. The present exploratory study aims to compare the effects of 2 training methods on both the behavioral welfare of the dog and the dog–owner relationship: the first method is based on positive reinforcement (appearance of an appetitive stimulus), whereas the second method is based on negative reinforcement (disappearance of an aversive stimulus). The study compared behaviors linked to signs of stress and attentive behaviors toward the owner in 2 dog training schools, which used different methods. Walking on-leash activity and obeying the “sit” command were studied. The results show that dogs from the school using a negative reinforcement–based method demonstrated lowered body postures and signals of stress, whereas dogs from the school using a positive reinforcement–based method showed increased attentiveness toward their owner. However, neither method affected avoidance behaviors. This exploratory study reveals the differential effects of the 2 training methods on dogs' behaviors; it suggests that training methods based on positive reinforcement are less stressful and potentially better for their welfare.     

Effect of TEX-OE® treatment on the development of heat shock proteins in commercial broiler chicks and the impact on performance indicators in the grow-out period

1. Heat shock proteins (HSPs) are highly conserved proteins, shown to protect organisms against physical and physiological stress.

2. TEX-OE^® is a patented total extract of the fruit of Opuntia ficus indica, which has been demonstrated to accelerate the development of HSPs in several animal species.

3. One-day-old commercial broiler chicks were treated with TEX-OE^®; HSP was measured by enzyme-linked immunosorbent assay (ELISA), and a large commercial field trial investigated key performance indicators (KPIs) in treated versus untreated controls chicks.

4. TEX-OE^® significantly increased HSP concentrations in treated chicks versus controls. Final cumulative mortality, liveweight and percentage factory-rejects were better than in controls.

5. The accelerated HSP response may enable chicks to cope with early stressors, which is reflected in improved KPIs.     

Elevation of shoot‐apices of two ecotypes of Themeda triandra on the Transvaal Highveld

In a series of investigations from 1965 to 1970 on the Transvaal Highveld it was found that trie elevation of shoot apices of two ecotypes of Themeda triandra was affected by season, ecotype and treatment. The absence of defoliation increased the susceptibility of the ecotypes to defoliation, whereas the shorter the defoliation the greater the subsequent resistance to grazing. The most important finding was that general application of earlier research findings from Natal was not possible in this case.     

The influence of the cuticle on egg‐shell strength

1. Sixty sound eggs, assumed to have shell cuticle, were paired according to egg‐shell deformation value.

2. Egg weight and shell quality characteristics were recorded for the eggs and the cuticle was then removed from one egg of each pair.

3. Egg weight and shell quality were re‐assessed for the eggs from which the cuticle had been removed.

4. The cuticle made a significant (P<0.01) contribution to shell thickness and removal of it appeared to reduce shell strength when measured directly, but the method of measurement was too variable to establish this with statistical significance.     

Survey of brucellosis at the wildlife–livestock interface on the Zimbabwean side of the Great Limpopo Transfrontier Conservation Area

A cross-sectional study was conducted to determine the seroprevalence of bovine brucellosis in communal cattle and wildlife at a wildlife–livestock interface in the southeast lowveld of Zimbabwe, part of the Great Limpopo Transfrontier Conservation Area. RBT and c-Elisa were used in serial for detection of antibodies against Brucella spp. Between July 2007 and October 2009, a total of 1,158 cattle were tested and the overall seroprevalence of brucellosis was 9.9%. A total of 97 wild animals (African buffaloes (n = 47), impala (n = 33), kudu (n = 16), and giraffe (n = 1)) were tested and only one animal (giraffe) was seropositive for brucellosis (1.03%). Brucella seroprevalence showed an increasing trend with age, with adult cattle (>6 years) recording the highest seroprevalence (11.1%), but the differences were not statistically significant. Similarly, female cattle recorded a relatively higher seroprevalence (10.8%) compared to males (7.9%), but the difference was not significant. However, a significant (P < 0.001) association between Brucella seropositivity and abortion history was recorded in female cattle. Similarly, Brucella seropositivity was significantly (P < 0.01) associated with a history of grazing in the park for female cattle. Overall, from the interface area, cattle with a history of grazing in the park recorded a significantly (P < 0.01) higher Brucella seroprevalence (13.5%) compared to those with no history of grazing in the park (4.9%). The significant association between abortion history and seropositivity observed in this study illustrates the potential economic significance of Brucella in cattle in this area. Hence, public awareness and further epidemiological studies of the disease in wildlife, livestock, and humans in the study area are of great importance.