胚胎移植安格斯犊牛适应性研究

湖北省于 2 0 0 0年 5月和 11月分两批利用胚胎移植技术 (以地方黄牛为受体 )引进了新西兰安格斯肉牛品种。本项目对第 1批胚移所产犊牛在湖北的适应性进行了研究。这批胚移犊牛表现了较好的生长发育与良好的适应性。它们的平均出生重与 3月龄内的日增重分别为 33.7(母 )～ 37.6 (公 )kg和 0 .75 1(公 )～ 0 .75 6 (母 )kg。但也发现了犊牛培育上出现的某些问题 ,如生长速度不很高 ,有一定的发病率 (如腹泻、上呼吸道感染、贫血 )。研究认为 ,出现这些问题的原因主要有 :没有充分满足生长犊牛的营养需要 ,湖北襄阳的生态环境条件与引入地 (新西兰 )的差别 ,饲养方式上从放牧向舍饲的改变 ,兽医缺乏犊牛的临床经验等。建议应用胚胎移植技术引进牛品种和培育胚移犊牛时 ,应注意尽量选择杂交牛与个体较大、尻部 (骨盆腔 )发育好的母牛做受体 ,重视母牛科学饲养 ,喂好犊牛初乳 ,重视犊牛补饲 ,改善环境条件 ,加强卫生防疫与防病治病工作。     

The potential of small ruminant farming as a means of poverty alleviation in rural southern India

Small ruminant production has the potential to address the global challenge of greatly increased food production in impoverished rural areas in a manner that is socioeconomically sustainable and carbon efficient. Twenty-six small ruminant landless farmers in three villages in the Kanchipuram District of the state of Tamil Nadu were surveyed with regard to their sheep farming practice and production indices, with the preliminary aim of evaluating the potential of small ruminant farming in alleviating poverty in parts of rural in southern India. The small ruminant farmers reared mostly indigenous Madras Red sheep as a means of generating primary or supplementary income. Participatory interviews were undertaken to enable the completion of a questionnaire pertaining to sheep production over the four most recent annual production cycles (referred to as instances) at the time of the study. When calculating the annual farm profits without taking into consideration the opportunity cost of labour, 83% of annual sheep production cycles over a 4-year period added to household incomes. Further, 23% of the instances that accounted for the opportunity cost of labour, household income was raised above the Indian Government’s defined poverty line solely through small ruminant farming. Management practices were identified, while participating in landless farmer interviews provided an insight into the husbandry, or lack thereof, which resulted in low lambing percentages and rates of high ewe losses, perinatal lamb mortality and abortion. The study showed both the vulnerability and potential resilience of small ruminant farming to natural disaster, in this case catastrophic flooding in 2015. While small ruminant farming generated income in most instances, the way it is practiced creates opportunities for simple changes in husbandry and management that could make it more efficient in poverty alleviation.

     

Evaluation of the long-term oral consequences of equine exodontia in 50 horses

The aims of this study were to objectively evaluate and quantify the process of post-extraction cheek teeth (CT) dental drift in horses, and to report on associated disorders of CT wear and long-term periodontal health. Fifty horses that had CT oral extraction because of apical infection were prospectively re-examined and a full oral examination, including measurements of some dental parameters, was performed.Narrowing of the extraction space was noted in all cases with complete closure occurring in 18% of horses. The rate of dental drift was calculated as 15.7% of extraction space/year (range 4–50%) and was not associated with the age at extraction (P = 0.78) or frequency of dental care since extraction (P = 0.48). There was a significant negative relationship between the rate of dental drift and the duration of time since extraction (P = 0.008). Overgrowths were present on the opposite CT row in 98% of horses, including opposite the extracted CT and on the Triadan 06s and 11s. No significant difference was noted in either the number of diastemata (P = 0.9) or periodontal disease score (P = 0.8) between the extraction and the contralateral cheek tooth rows.     

Temporal dynamics of nutrient and carbohydrate distribution during crop cycles of Rosa spp. ‘Kardinal’ in response to light availability

Rose plants that are flush harvested exhibit episodic growth patterns. During these crop cycles little biomass accumulation occurs immediately following harvest; and as new shoots emerge a period of rapid shoot growth and biomass accumulation occurs. The temporal changes in whole-plant nutrient and carbohydrate distribution during these crop cycles and the role of storage in new shoot growth are not well documented. The objective of this project was to quantify N, P, K, and total non-structural carbohydrates (TNC) distribution in roots, base stems, base leaves, and new shoots during crop cycles in response to light availability. Plants were grown in solution culture under high or low light (mean daily light integral 45.3 or 13.1 mol m⁻² d⁻¹, respectively) during 30–35 day crop cycles. Every five days destructive sampling was used to determine biomass and N, P, K, and TNC concentration of rose plant compartments. N and TNC accumulated in base plant compartments during the first ten days of the crop cycles. N, P, K, and TNC in base plant compartments declined during days 10–25 during a crop cycle concurrent with the rapid growth of flower shoots. N, P, and K storage in base plant parts represents 27, 22, and 24% of the potential N, P, and K required by flower shoots under high light; and 19, 21, and 22% of requirements under low light. TNC storage in base plant parts represents 4–10% of the final biomass of flower shoots. Mobilization of N, P, K, and TNC stored from base plant parts appears to be important during the stage of rapid flower shoot growth when absorption by roots or photosynthesis by shoots was insufficient to meet flower shoot demands. Plant carbohydrate status was improved under high light conditions; storage of N and TNC declined under low light.     

Identification of recombination hotspots and quantitative trait loci for recombination rate in layer chickens

Background: The frequency of recombination events varies across the genome and between individuals, which may be related to some genomic features. The objective of this study was to assess the frequency of recombination events and to identify QTL(quantitative trait loci) for recombination rate in two purebred layer chicken lines.Methods: A total of 1200 white-egg layers(WL) were genotyped with 580 K SNPs and 5108 brown-egg layers(BL)were genotyped with 42 K SNPs(single nucleotide polymorphisms). Recombination events were identified within half-sib families and both the number of recombination events and the recombination rate was calculated within each0.5 Mb window of the genome. The 10% of windows with the highest recombination rate on each chromosome were considered to be recombination hotspots. A BayesB model was used separately for each line to identify genomic regions associated with the genome-wide number of recombination event per meiosis. Regions that explained more than 0.8% of genetic variance of recombination rate were considered to harbor QTL.Results: Heritability of recombination rate was estimated at 0.17 in WL and 0.16 in BL. On average, 11.3 and 23.2 recombination events were detected per individual across the genome in 1301 and 9292 meioses in the WL and BL,respectively. The estimated recombination rates differed significantly between the lines, which could be due to differences in inbreeding levels, and haplotype structures. Dams had about 5% to 20% higher recombination rates per meiosis than sires in both lines. Recombination rate per 0.5 Mb window had a strong negative correlation with chromosome size and a strong positive correlation with GC content and with CpG island density across the genome in both lines. Different QTL for recombination rate were identified in the two lines. There were 190 and 199 non-overlapping recombination hotspots detected in WL and BL respectively, 28 of which were common to both lines.Conclusions: Differences in the recombination rates, hotspot locations, and QTL regions associated with genomewide recombination were observed between lines, indicating the breed-specific feature of detected recombination events and the control of recombination events is a complex polygenic trait.     

Assessment of gastrointestinal nematode infection,anthelmintic usage and husbandry practices on two small-scale goat farms in Malaysia

Haemonchosis is a common problem on goat farms in tropical countries such as Malaysia. Prevention of production losses generally depends on the use of anthelmintic drugs, but is threatened by the emergence of anthelmintic resistance. This study investigates anthelmintic efficacy on small-scale Malaysian goat farms and describes putative risk factors. Adult goats had moderate to high pre-treatment faecal trichostrongyle egg counts, despite being housed on slatted floors and fed on cut-and-carry forage, raising questions about the source of nematode infection. Our results show multiple resistance to benzimidazole and macrocyclic lactone anthelmintic drugs and allow us to discuss the genetic origins of resistance with reference to farm husbandry and management. We conclude that improvement in Malaysian goat production efficiency will require the development of sustainable helminth control strategies, underpinned by a better understanding of the origins and population genetics of anthelmintic resistance.