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排序方式: 共有169条查询结果,搜索用时 15 毫秒
1.
W. G. Haile S. Banerjee A. Ayele T. Mestawet G. Klemetsdal T. Ådnøy 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2018,68(4):174-180
ABSTRACTThe present study was conducted to estimate milk production performance and fit lactation curves for groups of ewes of Local and of Awassi crosses, with a variable blood level, reared under farmer’s environment. The Weigh-Suckle-Weigh method plus hand milking was used to estimate milk yield for ewes. A total of 466 observations from 115 ewes were used. Estimated least-squares adjusted means for the milk production over 120 days were 0.56?kg day?1 (Local), 0.67 (<30% Awassi), 0.86 (30–50% Awassi), and 0.96 (>50% Awassi). Groups with 30–50% Awassi and >50% Awassi ewes produced significantly (p?<?0.05) more milk than Local ewes. Significant differences were observed between <30% Awassi and >50% Awassi crossbred groups. The best crosses (>50% Awassi) produced over 70% more milk than the local ewes which demonstrates the potential that exists in increasing milk production through the initiated crossbreeding programme with sheep in Ethiopia. 相似文献
2.
Xiaofeng Ren Xun Wei Haile Ma Huiji Zhou Jingjing Guo Shuyun Mao An Hu 《Cereal Chemistry》2015,92(2):193-197
We investigated the effects of a dual‐frequency frequency‐sweeping ultrasound (DFFSU) treatment on the functional properties and structure of zein. The solubility of ultrasound‐treated zein proteins increased slightly but significantly as the treatment time increased. The results showed that the DFFSU treatment had an obvious influence on the mean particle size and the size distribution. A significant (P < 0.05) increase in the size of the particles with respect to time was observed after a sonication time of more than 20 min in zein solutions. Differential scanning calorimetry results showed that sonication alters the thermal behavior of zein. Circular dichroism spectra showed a small increase in the percentage of ordered structure elements within the protein molecule. After 60 min of ultrasonication, the percentage of α‐helix structures increased by 0.9%, whereas the percentage of β‐sheets and β‐turns decreased by 0.5%. Microstructural analyses by scanning electron microscopy showed that several microholes appeared in the zein following ultrasonic pretreatment. Under the conditions investigated in this study, DFFSU treatment was found to affect the studied functional properties of the zein protein. This technology could be used to obtain improved functional properties in some protein samples. 相似文献
3.
采用超声波处理小麦胚芽球蛋白以提高其功能性质.研究了超声波处理对小麦胚芽球蛋白理化和功能性质的影响.结果表明:经超声波处理后,小麦胚芽球蛋白的巯基和二硫键含量、紫外光谱和荧光光谱均发生了显著的变化.随着超声波功率的增加,小麦胚芽球蛋白的疏水性、起泡性、起泡稳定性、乳化性和乳化稳定性都降低;当超声波功率大于900 W时,由于小麦胚芽球蛋白重新伸展,疏水基团暴露增多,引起疏水性、起泡性、起泡稳定性、乳化性和乳化稳定性增加.此外.超声波功率对小麦胚芽球蛋白的溶解度有显著影响,随着超声波功率的增加其溶解度明显增加.因此,通过选择适宜的超声波功率水平能够改善小麦胚芽球蛋白的理化和功能性质. 相似文献
4.
牡丹籽油超声波辅助提取工艺的响应面法优 总被引:7,自引:1,他引:6
为优化牡丹籽油的超声波辅助提取工艺,在单因素试验基础上,选择液料比、超声波功率、处理时间、处理温度为自变量,牡丹籽油得率为响应值,采用Box-Behnken试验设计方法,研究各自变量及其交互作用对牡丹籽油得率的影响.利用Design Expert软件得到回归方程的预测模型并进行响应面分析,确定超声波辅助提取牡丹籽油的最佳条件为:液料比11 mL/g,超声波功率300 W,处理时间60 min,处理温度54℃,提取次数为3次.在该工艺条件下,牡丹籽油得率达24.12%.GC-MS结果表明牡丹籽油中富含不饱和脂肪酸,其中亚油酸和亚麻酸的质量分数分别为22.78%和64.14%. 相似文献
5.
6.
The Effect of Season on Spermatozoa Motility,Plasma Membrane and Acrosome Integrity in Fresh and Frozen–Thawed Semen from Xinong Saanen Bucks
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W Wang J Luo S Sun L Xi Q Gao AB Haile H Shi W Zhang H Shi 《Reproduction in domestic animals》2015,50(1):23-28
The aim of this study was to evaluate whether the season of ejaculate collection influences seminal quality parameters of pre‐ and post‐freeze–thawing in Xinong Saanen bucks. Ejaculates were collected from eight bucks throughout the four seasons (spring, summer, autumn and winter) in a 12 months’ time period, identified in the Northern Hemisphere. Semen samples were evaluated by the combinations of conventional and Computer‐Assisted Sperm Analysis (CASA) when fresh and after frozen–thawed, respectively. The results clearly demonstrated that season of ejaculate collection influenced (p < 0.05) fresh semen quality. Highest semen quality was observed during autumn. On the contrary, undesirable indices (significantly lower, p < 0.05) were observed in winter as compared with the other remaining seasons. CASA has clearly shown the influences of seasonal variations on semen motility parameters. Furthermore, season of ejaculate collection was also found to influence sperm freezability. Semen characteristics after frozen–thawed followed a similar pattern with that of fresh ejaculate except in spring. The results revealed that sperm quality was higher (p < 0.01) in summer and autumn than in spring and winter. In conclusion, seasonal variation influences semen quality in Xinong Saanen bucks. In addition to summer and autumn, fresh ejaculates in spring can also be successfully used for AI. Sperm from ejaculates collected during summer and autumn are more suitable for cryopreservation. Hence, it is possible to increase the efficiency of goat breeding by manipulating the seasonal variations of semen quality for immediate AI and/or cryopreservation. 相似文献
7.
S. Gizaw J.A.M. van Arendonk A. Valle‐Zárate A. Haile B. Rischkowsky T. Dessie A.O. Mwai 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2014,131(5):350-357
A simulation study was conducted to optimize a cooperative village‐based sheep breeding scheme for Menz sheep of Ethiopia. Genetic gains and profits were estimated under nine levels of farmers' participation and three scenarios of controlled breeding achieved in the breeding programme, as well as under three cooperative flock sizes, ewe to ram mating ratios and durations of ram use for breeding. Under fully controlled breeding, that is, when there is no gene flow between participating (P) and non‐participating (NP) flocks, profits ranged from Birr 36.9 at 90% of participation to Birr 21.3 at 10% of participation. However, genetic progress was not affected adversely. When there was gene flow from the NP to P flocks, profits declined from Birr 28.6 to Birr ?3.7 as participation declined from 90 to 10%. Under the two‐way gene flow model (i.e. when P and NP flocks are herded mixed in communal grazing areas), NP flocks benefited from the genetic gain achieved in the P flocks, but the benefits declined sharply when participation declined beyond 60%. Our results indicate that a cooperative breeding group can be established with as low as 600 breeding ewes mated at a ratio of 45 ewes to one ram, and the rams being used for breeding for a period of two years. This study showed that farmer cooperation is crucial to effect genetic improvement under smallholder low‐input sheep farming systems. 相似文献
8.
Although research on dairy goat mammary gland have referred extensively to molecular mechanisms, research on lines of dairy goat mammary epithelial cells (MECs) are still rare. This paper sought to establish an immortal MEC line by stable transfection of human telomerase. MECs from a lactating (45 days post‐parturition) Xinong Saanen dairy goat were cultured purely and subsequently transfected with a plasmid carrying the sequence of human telomerase. Immortalized MECs by human telomerase (hT‐MECs) exhibited a typical cobblestone morphology and activity and expression levels of telomerase resembled that of MCF‐7 cells. hT‐MECs on passage 42 grew vigorously and ‘S’ sigmoid curves of growth were observed. Moreover, hT‐MECs maintained a normal chromosome modal number of 2n = 60, keratin 8 and epithelial membrane antigen (EMA) were evidently expressed, and beta‐casein protein was synthesized and secreted. Beta‐casein expression was enhanced by prolactin (P < 0.05). Lipid droplets were found in hT‐MECs, and messenger RNA levels of PPARG, SREBP, FASN, ACC and SCD in hT‐MECs (passage 40) were similar to MECs (passage 7). In conclusion, the obtained hT‐MEC line retained a normal morphology, growth characteristics, cytogenetics and secretory characteristics as primary MECs. Hence, it can be a representative model cell line, for molecular and functional analysis, of dairy goat MECs for an extended period of time. 相似文献
9.
合成含有鸡法氏囊病毒抗原表位核酸序列的4条引物,利用SOE-PCR (重叠延伸PCR法)方法克隆得到含鸡法氏囊病毒多抗原表位串联肽的核酸序列。通过EcoR I和Sal I 两个酶切位点使该核酸序列插入原核表达载体(pET32a)。SDS-PAGE 实验结果表明鸡法氏囊病毒重组多抗原表位串联肽在大肠杆菌中的表达量为20%左右。Western blotting试验和免疫琼脂扩散沉淀试验(AGP)的结果均表明鸡法氏囊病毒重组多抗原表位串联肽具有明显的抗原性。 相似文献
10.
Effectiveness of stone bunds in controlling soil erosion on cropland in the Tigray Highlands, northern Ethiopia 总被引:4,自引:0,他引:4
Desta Gebrernichael J. Nyssen J. Poesen J. Deckers Mitiku Haile G. Govers J. Moeyersons 《Soil Use and Management》2005,21(3):287-297
Abstract Use of stone bunds to enhance soil and water conservation was first introduced to Tigray, northern Ethiopia in 1981. This study was designed to examine the factors that control the effectiveness of bunds installed on cropland. Qualitative and quantitative assessments of soil loss and sediment accumulation were conducted on 202 plots at 12 representative sites in Dogu'a Tembien district. Mean annual soil loss from the foot of the bunds due to tillage erosion was estimated at 39kgm−1 yr−1 or 20tha−1 yr−1 , a rate which decreased with increasing age of bund. The assessed mean annual soil loss rate by sheet and rill erosion in the absence of stone bunds is 57tha−1 yr−1 . The mean measured annual rate of sediment accumulation behind the stone bunds is 119kgm−1 yr−1/sp or 59tha−1 yr−1 . The measurements show that the introduction of stone bunds to the region has led to a 68% reduction in annual soil loss due to water erosion. This reduction is due to the accumulation of sediment behind the stone bunds, which occurs faster in the early years after construction and decreases as the depression behind the bunds becomes filled with sediment. New stone bunds are particularly effective in trapping sediment in transport, but regular maintenance and increase in height of the bunds is necessary to maintain their effectiveness. The average USLE P factor for stone bunds in the study area is estimated to be 0.32. 相似文献