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1.
K Ashley S Wilson JR Young HP Chan S Vitou S Suon PA Windsor RD Bush 《Tropical animal health and production》2018,50(1):63-73
Forage technology has been successfully introduced into smallholder cattle systems in Cambodia as an alternative feed source to the traditional rice straw and native pastures, improving animal nutrition and reducing labour requirements of feeding cattle. Previous research has highlighted the positive impacts of forage technology including improved growth rates of cattle and household time savings. However, further research is required to understand the drivers, challenges and opportunities of forage technology for smallholder cattle households in Cambodia to facilitate widespread adoption and identify areas for further improvement. A survey of forage-growing households (n = 40) in July–September 2016 examined forage technology adoption experiences, including reasons for forage establishment, use of inputs and labour requirements of forage plot maintenance and use of forages (feeding, fattening, sale of grass or seedlings and silage). Time savings was reported as the main driver of forage adoption with household members spending approximately 1 h per day maintaining forages and feeding it to cattle. Water availability was reported as the main challenge to this activity. A small number of households also reported lack of labour, lack of fencing, competition from natural grasses, cost of irrigation and lack of experience as challenges to forage growing. Cattle fattening and sale of cut forage grass and seedlings was not found to be a widespread activity by interviewed households, with 25 and 10% of households reporting use of forages for these activities, respectively. Currently, opportunities exist for these households to better utilise forages through expansion of forage plots and cattle activities, although assistance is required to support these households in addressing current constraints, particularly availability of water, if the sustainability of this feed technology for smallholder cattle household is to be established in Cambodia. 相似文献
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Phytophthora root rot, caused byPhytophthora cinnamomi Rands, is the most important disease of avocado (Persea americana Miller). In an attempt to identify root rot-resistant rootstocks that could ultimately be used under conditions in southern
Florida, we screened open-pollinated progeny of avocado from the National Germplasm Repository in Miami. From 1996 to 1998,
a total of 2,355 seedlings from 51 accessions were examined in potting mix artificially infested withP. cinnamomi. Most seedlings developed severe root rot, but tolerance was observed in some families (i.e., progeny of certain accessions). Although the most susceptible families developed mean disease ratings of up to 97% root
necrosis, mean ratings for the most tolerant families were less than 60%. There was also a strong relationship between the
racial background of the female parent and the tolerance of seedlings. Seedlings of the West Indian race and hybrids between
it and the Guatemalan race were significantly more tolerant than those from other parents (P< 0.05). Individuals in several
families developed < 50% root necrosis, the arbitrary standard of tolerance in this study. Twelve families accounted for 82%
(188 of 229) of the tolerant seedlings, and only two of these did not have a West Indian or Guatemalan × West Indian pedigree.
Broad-sense heritability for PRR tolerance was 0.45. This is the first report on the inheritance of PRR tolerance in avocado
and on the influence of genotype and racial pedigree under controlled conditions. 相似文献
4.
Bluetongue (BT) is an insect transmitted viral disease of sheep that often causes mild or inapparent disease but rarely causes severe disease in cattle. Until recently, bluetongue viral infection was believed to be more prevalent in the Western United States, as compared with other regions of the country. However, a national survey for bluetongue antibody and clinical evidence of the disease in the Southeastern United States prompted the present investigation that was designed to determine the serological prevalence of BT virus in Alabama cattle. Results of the study demonstrated that 16% of the samples collected from 1,500 cattle in 64 of the 67 counties were positive. The prevalence of positive cattle in the western part of the State was significantly higher (P less than .001) than the prevalence in the eastern half of the State. On a herd basis, 52% of all herds tested had positive animals. Results of this study suggest that bluetongue infection is more common in the Southeastern United States than previously suspected. 相似文献
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Manufactured soil for landscaping purposes was produced by composting for 6 weeks (1) municipal green waste alone, (2) green
waste amended with 25% v/v poultry manure, or (3) green waste immersed in, and then removed from, a mixture of liquid grease trap waste/septage. Composting
temperatures increased most rapidly and reached highest values (78oC) in the grease trap/septage-amended green waste. In comparison
with green waste alone, addition of poultry manure prolonged the period of elevated temperatures and increased the maximum
temperature attained from 52oC to 61oC. Following composting, each of the materials was split into (1) 100% compost, (2) 80%
compost plus 20% v/v soil, and (3) 70% compost plus 20% soil plus 10% coal fly ash. Addition of poultry manure or grease trap/septage to green
waste prior to composting increased bulk density and reduced total porosity of the composted product. Addition of soil, or
soil and ash, to composts increased bulk density, reduced total porosity, decreased percentage macropores, and increased percentage
mesopores and available water-holding capacity. Bicarbonate-extractable P, exchangeable NH4+ and NO3−, electrical conductivity (EC), soluble C, soluble C as a percentage of organic C, basal respiration, and metabolic quotient
were all markedly greater in the grease trap/septage-amended than poultry manure-amended or green waste alone treatments.
Values for extractable P and EC were considered large enough to be damaging to plant growth and germination index (GI) of
watercress was less than 60% for all grease trap/septage composts. Extractable P and EC were also high, and GI was <100%,
in the green waste alone and poultry manure-amended green waste alone treatments. Addition of soil or soil and ash to these
composts resulted in GI values >100%. 相似文献
7.
为探究人工施用竹炭对卷心菜叶绿素含量和荧光参数的影响,进而明确卷心菜的最适竹炭有机肥施用量,在田间试验条件下设置了无碳(CK)、中碳(MC)和高碳(SC)3个处理,对卷心菜莲座期和结球期的叶绿素含量及荧光参数进行测量研究.结果表明:(1)结球期的卷心菜叶绿素含量极显著高于莲座期(p0.01),且随着竹炭量的增加,两个时期的叶绿素含量变化趋势一致,从高到低依次为:MC,CK,SC.(2)结球期的卷心菜初始最小荧光Fo、初始最大荧光Fm、PSⅡ的最大光化学效率Fv/Fm,PSⅡ的潜在活性Fv/Fo、非光化学猝灭系数qN均低于莲座期,而PSⅡ实际光化学效率ΦPSⅡ、光化学猝灭系数qP高于莲座期,且随着竹炭量的增加,两个时期的这些参数均表现出一致的变化趋势,Fo和qN均呈"V"型变化,而Fm,Fv/Fm,Fv/Fo,ΦPSⅡ和qP均呈现倒"V"趋势,但对ΦPSⅡ和qP没有显著影响(p0.05).说明结球期的卷心菜光合作用高于莲座期;当竹炭量由CK增加到MC,有利于提高叶片叶绿素含量,增强光能利用率,减少植株热耗散,提高植株光合作用;但随着竹炭量进一步增加到SC,卷心菜叶片叶绿素含量降低,光能利用率减弱,热耗散增加,光合作用受到抑制,即中炭(MC)处理条件下,此卷心菜长势最优,表明中炭是该卷心菜生长的最适竹炭有机肥施用量. 相似文献
8.
PA Accorsi N Govoni R Gaiani C Pezzi E Seren C Tamanini 《Reproduction in domestic animals》2005,40(3):217-223
Leptin may play a role in the endocrine-metabolic processes that guarantee the physiological course of lactation in dairy cattle. This study was aimed at determining the changes in plasma concentrations of leptin and some of the main hormones and metabolites involved in the lactogenetic process in high-yielding dairy cows throughout lactation; we also wanted to assess whether leptin secretion is subjected to seasonal influences. Blood samples were collected from 23 Italian Friesian dairy cows from the end of a lactation to the ninth month of the subsequent one; in addition, blood was sampled from 47 dairy cows in different phases of lactation during February and July. Plasma concentrations of leptin, growth hormone (GH), insulin, prolactin (PRL), glucose, non-esterified fatty acids (NEFA) and urea were quantified by either validated radioimmunoassay (RIA) or enzymatic colorimetric methods. At the beginning of lactation, GH concentrations significantly increased, while a significant reduction occurred in leptin and insulin. This endocrine condition, such as the significant increase in NEFA plasma concentrations, is indicative of a marked lipid mobilization. In the more advanced stages of lactation, when both energy and protein balances become positive, leptin plasma concentrations increased, whereas GH and NEFA concentrations declined. During the summer months, a significant increase in leptin plasma concentrations, irrespective of the phase of lactation, was observed. Collectively, our findings suggest that, in dairy cows, leptin may represent a 'metabolic signal' of animal's status of fattening and nutritional level; in addition, leptin seems to be influenced by photoperiod and environmental temperature. 相似文献
9.
Diflufenican, a pre- and early post-emergence herbicide, was found to be highly active against a wide range of weeds at application rates of 50–250 g ha-1. Studies on the mode of selectivity with [14C]diflufenican have demonstrated that selectivity between cereal crops and selected weed species is primarily due to differential uptake and indirectly to translocation; ‘depth protection’ appears to be the major reason for selectivity of soil-applied diflufenican. 相似文献
10.