Has the introduction of modern rice varieties changed rice genetic diversity in a high-altitude region of Nepal?

We surveyed the uptake of three modern rice varieties by farmers in high-altitude villages in the Kaski district of Nepal and found that their uptake had displaced some traditional landraces in the district. The three varieties, Machhapuchhre-3 (M-3), Machhapuchhre-9 (M-9) and Lumle 2, were developed using client-oriented, participatory plant breeding methods and the first was introduced to farmers in 1996. By 2004 up to 60% of the land area was used to grow these modern varieties. Molecular markers (SSR) were used to assay levels of genetic diversity to test if adoption of modern varieties in the place of landraces had changed genetic diversity. The modern varieties were found to contain diverse alleles with a high proportion from the local parent variety, Chhomrong Dhan. We found a high level of allelic richness in the landraces, and although seven had been dropped in favour of the modern varieties, other diverse landraces were still being cultivated by farmers in the study villages on up to 40% of the rice area. Genetic diversity may be maintained even when landraces are displaced by modern varieties. Using a model we found that the partial replacement of landraces increased genetic diversity if the modern varieties were adopted on up to 65% of the area. Only above these levels did overall diversity decline.     

Survival of scrapie agent after exposure to sodium dodecyl sulphate and heat.

Fifty mg aliquots of macerated mouse-brain infected with the 22A strain of scrapie agent were treated by exposing them without mechanical mixing to (a) distilled water for 2 h, (b) 5% sodium dodecyl sulphate (SDS) for 2 h, (c) autoclaving at 121 degrees C for 15 min in distilled water, (d) autoclaving at 121 degrees C for 15 min in 5% SDS, or (e) boiling in 5% SDS for 15 min. Prior to injection into mice, all samples were washed by a procedure that is described and was shown not to reduce infectivity titres. Although the infectivity titre of the sample that was autoclaved in SDS was reduced considerably, infectivity was present in all of the samples exposed to cold or hot SDS.     

Selection line x diet interactions for two lines of pigs fed 12 or 24% protein diets

An experiment with crossbred swine was conducted over six generations of selection based on an index (Index) of average daily gain in weight (ADG) in a test period from 56 d of age to 91 kg gross weight and average backfat thickness (ABF) measured from ultrasonic scans at 91 kg. Test pigs of the high protein select (HS) and control (HC) lines were fed a 24% crude protein (CP) diet and pigs of the low protein select (LS) and control (LC) lines were fed a 12% CP diet during the test period. The extent of genetic (selection line) x environmental (dietary) interaction effects was determined based on feeding closely related boars and gilts from both the HS and LS lines on both diets. Tests were conducted in 1986 and 1987 with progeny of the fifth and sixth generations of selection. Records for 472 pigs sired by 37 boars and out of 101 dams were analyzed for effects of selection and diets on AGE of pig at 91 kg, ADG, ABF, LMA (longissimus muscle area at the last rib) and Index. Statistically significant interactions effects of line x diet were noted (P less than .01) for AGE, ADG and Index, traits with low to moderate heritabilities (h2). For ABF and LMA, body composition traits with moderate or higher h2, interaction effects of line x diet were near zero. These results suggest that for best all-around future performance, traits such as AGE and ADG, selection probably should be practiced under dietary conditions under which future populations will be produced. For body composition traits such as ABF and LMA, selection probably would be more effective if pigs were fed a more enriched protein diet. However, as a practical matter, to more rapidly improve the genetic merit of the swine population, both the central station and on-the-farm testing programs should be conducted under standard commercial production systems.     

An investigation into the aetiology of 'wool slip': alopecia in ewes which are housed and shorn in winter

Alopecia in housed ewes which are shorn in winter, 'wool slip', was investigated by taking wool and blood samples, skin scrapings and biopsies from affected and unaffected animals. Epidemiological information was also obtained from farm records, and reports from a local weather station. No pathological lesions were seen and no ectoparasites or forage mites were seen in wool samples or skin scrapings. The plasma zinc and copper concentrations of both groups were within the normal range but the copper concentrations were significantly lower in the unaffected animals. There was no difference between the prevalence of the disease in ewes of different breeds or between those producing single or twin lambs. A comparison of the mean temperatures during years of summer and winter shearing suggested that cold stress alone was not involved. Skin biopsies revealed that the wool follicles of affected animals were in an early growth phase (anagen) whereas those of unaffected animals were in the inactive phase (telogen). The clinical and histological signs of the disease were similar to those seen experimentally when corticosteroids are used as chemical depilatory agents. It is suggested that wool slip is due to the high levels of corticosteroids which occur as a result of the combination of housing and shearing and on this basis methods of control are proposed.     

Organophosphorus residues in wool grease resulting from specified on-farm lice and flystrike control treatments

Objective To investigate wool organophosphorus concentrations resulting from a range of farm pesticide application methods.
Design Random sampling of wool for pesticide residues and on-farm interviews to determine associated treatments.
Procedure Tasmanian fleece wool lots were sampled at random and tested for organophosphorus residues. The grower was identified and the pesticide treatments applied to the sheep were ascertained by on-farm interview.
Results The residue concentrations showed a large variation that was not accounted for by differences in treatments by growers. Organophosphorus concentrations were proportional to the number of treatments applied, and inversely related to the time between pesticide application and the subsequent shearing, and were significantly influenced by the method of application. After allowing for the time of application, plunge dipping resulted in pesticide residue concentrations 2 to 2.5 times greater than shower dipping, using spray races or hand jetting, and the use of these methods caused larger residues than the use of jetting races.
Conclusions We recommend that plunge or shower dipping should not be used more than 7 weeks after shearing, nor at higher concentration than the standard dose rate used for lice control, whereas jetting may be satisfactory for up to 7 months after shearing, provided only one application is administered.     

Effects of intravenous xylazine hydrochloride on blood glucose, plasma insulin and rectal temperature in neonatal foals

The effects of intravenous xylazine hydrochloride on blood glucose, plasma insulin and rectal temperature were investigated in six foals at 10 and 28 days of age. These variables were also measured in three foals at 19 days of age when saline alone was injected. Rectal temperature fell significantly after 30 mins in both groups of xylazine treated foals and was still depressed after 120 mins. Hypothermia did not occur in the saline control group. There was no significant change in blood glucose or plasma insulin concentrations during the 120 mins following either xylazine or saline administration and no significant differences between the three groups of foals. When foals were allowed to suckle after being away from their dams for 2 h, there was a significant (P less than 0.01) rise in plasma insulin levels in all the groups. Blood glucose showed a concomitant rise but this was only significant in the saline group. Unlike adults, intravenous xylazine (1.1 mg/kg) does not produce hypoinsulinaemia and hyperglycaemia in foals. This study suggests that the inhibition of insulin release from pancreatic beta-cells by xylazine, which in adults is alpha 2-adrenoceptor mediated, is immature or absent in foals under one month of age.     

Effects of exogenous porcine growth hormone administration between 30 and 60 kilograms on the subsequent and overall performance of pigs grown to 90 kilograms

Twenty-eight barrows were used to investigate the effects of exogenous porcine growth hormone (pGH) administration (0 and 100 micrograms.kg-1.d-1) between 30 and 60 kg on the subsequent and overall performance and carcass composition of pigs grown to 90 kg. The pGH was administered by daily i.m. injection and all pigs were fed one diet. Control animals were pair-fed to the intake noted for pGH-treated pigs between 30 and 60 kg and all pigs were fed ad libitum from 60 to 90 kg. Pigs administered pGH had an improved rate (36%) and efficiency (28%) of gain and an improved protein accretion rate (46%) compared to excipient-treated pigs. Pigs previously treated with pGH continued to exhibit superior (P less than .01) rate and efficiency of gain, and the gain was associated with enhanced protein accretion during the quiescent (postinjection) period compared with excipient counterparts. Administration of pGH between 30 and 60 kg reduced carcass fat and increased carcass protein and water at 90 kg, although fat accretion rate was comparable to that of control pigs. Results indicate that, to varying degrees, the stimulatory effects of pGH on growth performance are sustained following cessation of hormone treatment.