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1.
本文根据具体机器动作协调性要求及其具体空间几何条件,采用了摆动从动件盘形凸轮机构。其摆杆推程在O°~52°及52°~62°范围内分别采用了等加速——等速合理拼接运动规律。回程在62°~153°范围内采用了正弦加速度运动规律。用极坐标矢量分析法建立方程、微分,通过电脑程序计算,设计制造出凸轮轮廓,用于禾苗移植机的擒纵机构处,完全符合生产要求,获得了理想的效果。 相似文献
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不同光质组合对生菜生长和能量利用效率的影响 总被引:1,自引:0,他引:1
【目的】筛选较优的光质组合,提高人工光植物工厂生菜产量和能量利用效率。【方法】以光强为200μmol/(m~2·s),R/B为4/1的红蓝光(RB)为对照,在光强为150μmol/(m~2·s),R/B为4/1的红蓝背景光基础上,分别添加50μmol/(m~2·s)的绿光(G)、黄光(Y)、橙光(O)和远红光(FR)组成4种不同光质组合处理,分别用RBG、RBY、RBO和RBFR表示,对不同光质组合处理生菜的生长及形态、光合能力、能量利用效率等指标进行比较研究。【结果】RBG、RBO和RBFR处理生菜地上部鲜质量较RB处理分别增加14.5%,14.5%和30.8%,地上部干质量分别增加13.3%,24.1%和29.9%(P0.05)。RBG处理可以增加生菜的株高、总叶面积、净光合速率和能量利用效率。与RB处理相比,RBY处理对生菜的地上部干、鲜质量影响不显著;RBO处理可以提高生菜叶片的光合能力和能量利用效率。RBFR处理可以增加生菜的地上部干、鲜质量,但在实际生产中,生菜叶片较易出现烧尖现象。【结论】RBG和RBO是工光植物工厂生产中较为合适的光质组合。 相似文献
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Emma T Helm Jason W Ross John F Patience Steven M Lonergan Elisabeth Huff-Lonergan Laura L Greiner Leah M Reever Chad W Hastad Emily K Arkfeld Nicholas K Gabler 《Journal of animal science》2021,99(1)
Although pork producers typically aim to optimize growth rates, occasionally it is necessary to slow growth, such as when harvest facility capacity is limited. In finishing pigs, numerous dietary strategies can be used to slow growth so pigs are at optimal slaughter body weights when harvest facility capacity and/or access is restored. However, the impact of these diets on pork carcass quality is largely unknown. Thus, this study aimed to evaluate the efficacy of dietary strategies to slow growth in late finishing pigs and evaluate their effects on carcass composition and pork quality. Mixed-sex pigs (n = 897; 125 ± 2 kg BW) were randomly allotted across 48 pens and assigned to 1 of 6 dietary treatments (n = 8 pens/treatment): (1) Control diet representative of a typical finisher diet (CON); (2) diet containing 3% calcium chloride (CaCl2); (3) diet containing 97% corn and no soybean meal (Corn); (4) diet deficient in isoleucine (LowIle); (5) diet containing 15% neutral detergent fiber (NDF) from soybean hulls (15% NDF); and (6) diet containing 20% NDF from soybean hulls (20% NDF). Over 42 d, pen body weights and feed disappearance were collected. Pigs were harvested in 3 groups (14, 28, and 42 d on feed) and carcass data collected. From the harvest group, 1 loin was collected from 120 randomly selected carcasses (20 loins/treatment) to evaluate pork quality traits. Overall, ADG was reduced in CaCl2, Corn, and 20% NDF pigs compared with CON pigs (P < 0.001). However, ADFI was only reduced in CaCl2 and 20% NDF pigs compared with CON (P < 0.001). Feed efficiency was reduced in CaCl2 and Corn pigs compared with CON (P < 0.001). Hot carcass weights were reduced in CaCl2 pigs at all harvest dates (P < 0.001) and were reduced in Corn and 20% NDF pigs at days 28 and 42 compared with CON pigs (P < 0.001). In general, CaCl2 and 20% NDF diets resulted in leaner carcasses, whereas the Corn diet increased backfat by 42 d on test (P < 0.05). Loin pH was reduced and star probe increased in CaCl2 pigs compared with CON pigs (P < 0.05); no treatments differed from CON pigs regarding drip loss, cook loss, color, firmness, or marbling (P ≥ 0.117). Overall, these data indicate that several dietary strategies can slow finishing pig growth without evidence of behavioral vices. However, changes to carcass composition and quality were also observed, indicating quality should be taken into consideration when choosing diets to slow growth. 相似文献
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John Ellis Sheryl Gow Carrie Rhodes Stacey Lacoste Lyndsay Kong Kristyna Musil Elisabeth Snead 《The Canadian veterinary journal. La revue veterinaire canadienne》2016,57(5):531-534
The immune responses in control dogs [1 to 4 years of age, body condition score (BCS): 4 to 5 out of 9] were compared to those of aging dogs (based on breed and body size) either categorized as lean (BCS: 4 to 5 out of 9) or obese (BCS: 8 to 9 out of 9). Of interest were the serum titers to the following common agents found in vaccines, canine parainfluenza virus (CPIV), canine parvovirus (CPV), canine distemper virus (CDV), canine respiratory coronavirus (CRCoV), and Bordetella bronchiseptica. There were no statistical differences in the antibodies to CPIV, B. bronchispetica, and CRCoV, among the age/weight categories, nor among the age/weight categories and the time, in days, between the date of sample collection and the date of the last recorded vaccination for CPIV, B. bronchiseptica, CPV, and CDV. For CPV, the control dogs had significantly (P < 0.002) higher serum neutralization (SN) titers than the lean geriatric dogs and the obese geriatric dogs. For CDV SN titers, the only statistically significant (P = 0.01) difference was that the control dogs had higher SN titers than the lean geriatric dogs. 相似文献
6.
Snead EC 《The Canadian veterinary journal. La revue veterinaire canadienne》2007,48(8):848-851
A rare, large granular lymphocyte (LGL) tumor causing a protein-losing enteropathy and thrombocytopenia was diagnosed in an Irish wolfhound. The case had an aggressive clinical course, like most LGL tumors in humans. Immunophenotyping suggested that the LGL tumor in this dog was derived from a natural-killer cell. 相似文献
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Rubber mats covering concrete slatted flooring are a developing market in dairy barns but remain rare in beef cattle facilities. The aim of this study was to investigate the effects of covering slatted concrete floor with perforated rubber mats on behaviour and occurrence of skin and claw lesions in fattening bulls. The groups of six bulls each with a total average age of 9.8 months were kept over 1 year on either slatted concrete (CONCRETE PEN) or on slatted concrete covered completely (RUBBER PEN) or partially (CHOICE PEN) with perforated rubber mats. Every quarter-year, behaviour (preference of flooring, lying, aggression, mounting) was recorded. In two-weekly intervals the incidence of skin lesions was examined. At 12 and 18 months of age the rising time of the bulls was measured. At the beginning of the study and after slaughter claw dimensions were recorded. Bulls in the CHOICE PEN preferred (P<0.01) the rubber coated area throughout the experiment. Animals in the RUBBER and the CHOICE PENS showed more lying periods (P<0.01) and had a lesser incidence of skin lesions (P<0.01) compared to bulls in the CONCRETE PEN. Bulls in the CHOICE PEN needed less time for rising (2.7+/-0.3s) than bulls in the CONCRETE PEN (4.4+/-0.5s, P<0.01). Net claw growth differed significantly between all pens (RUBBER>CHOICE>CONCRETE; P<0.05). In conclusion, the results of this study indicate that rubber coated slatted flooring has a positive influence on the housing conditions of beef cattle. 相似文献
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Journal of Plant Diseases and Protection - This study explores the food plant spectrum of the sugar beet weevil (Asproparthenis punctiventris Germar; Coleoptera: Curculionidae), one of the most... 相似文献
9.
Chitrita DebRoy Elisabeth Roberts 《Journal of veterinary diagnostic investigation》2006,18(6):597-600
Several outbreaks of Escherichia coli O157 have been reported in petting zoos, resulting in hospitalization of many children. At present, no standard procedure has been adopted to monitor the presence of enterohemorrhagic E. coli (EHEC) or Shiga-toxin-producing E. coli (STEC) in petting zoo animals. Direct detection of these strains from rectal swabs of animals in petting zoos was developed and obviated the need to culture the organisms. DNA extracted from bacteria in the swabs was tested for the presence of wecA gene specific for E. coli by polymerase chain reaction (PCR). The wecA positive samples were further tested for Shiga-toxin genes stxl and stx2, and the intimin eae by multiplex PCR and for the presence of O157 and H7. Swabs (n=104) from 15 animal species in a petting zoo were tested; 7 goats and 3 cows were found to carry STEC. The method is rapid and convenient for monitoring potentially pathogenic E. coli in petting zoo animals. 相似文献
10.
Leila Feiz Muhammad Irshad Rafael F Pont-Lezica Hervé Canut Elisabeth Jamet 《Plant methods》2006,2(1):10-13