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71.
According to two properties of the life cycle and to fluctuation with parities, four mathematical models, the Poisson cycle model, the cubic polynomial model, the modified quadratic polynomial model-I and the modified quadratic polynomial model-II, were used to fit the records of litter size in Jiangquhai sows. From the viewpoint of statistics and biological significance, the modified quadratic polynomial model-I was found to be the optimum model. A single trait animal model and DFREML procedures were further used to estimate the heritability values of optimum model parameters. The results show that the heritability values for the coefficients A and B and the heritability value for the acme of the model pure quadric curve are larger than the heritability value for the litter size. This suggests that selection for model parameters may be more effective than direct selection for litter size. 相似文献
72.
Weight loss in overwintering below‐ground parts of perennial weeds has been attributed to respiration, but neither its temperature dependence nor its relevance for biomass dynamics under changing climate conditions have been investigated. In two experiments, we quantified weight loss of the perennial weed Sonchus arvensis, by measuring weight changes over time of sprouting roots in dark rooms at temperatures of 4, 8 and 18°C. Dry weight loss rates were 0.47, 0.64 and 1.47% day?1 at 4, 8 and 18°C, respectively, giving a half‐life time of 149, 110 and 47 days, respectively. A factor by which weight loss rates increase for every 10° rise in temperature (Q10) was equal to about 2.3. Cumulative weight loss may comprise >40% of the below‐ground biomass during overwintering periods. Applying weight loss rates and Q10 to elevated soil temperature projections showed that losses during winter seasons in central Sweden will remain basically constant, the effect of increased weight loss at higher temperatures being balanced by shorter winters. This implies that need for control of S. arvensis in a changing climate will persist, but that shorter winter seasons will provide a longer time window for control of S. arvensis prior to sowing crops. 相似文献
73.
74.
BackgroundPorcine epidemic diarrhea virus (PEDV) is a swine enteropathogenic coronavirus that has devastated the swine industry in South Korea over the last 30 years. The lack of an effective method to control the endemics has led to a surge in PEDV recurrences in affected farms throughout the country.ObjectivesIn the first step toward establishing systematic monitoring of and active control measures over the swine populations, we constructed an assessment model that evaluates the status of (1) biosecurity, (2) herd immunity, and (3) virus circulation in each of the PEDV-infected farms.MethodsA total of 13 farrow-to-finish pig farms with a history of acute PEDV infection on Jeju Island were chosen for this study. The potential risk of the recurrence in these farms was estimated through on-site data collection and laboratory examination.ResultsOverall, the data indicated that a considerable number of the PEDV-infected farms had lax biosecurity, achieved incomplete protective immunity in the sows despite multi-dose vaccination, and served as incubators of the circulating virus; thus, they face an increased risk of recurrent outbreaks. Intriguingly, our results suggest that after an outbreak, a farm requires proactive tasks, including reinforcing biosecurity, conducting serological and virus monitoring to check the sows’ immunity and to identify the animals exposed to PEDV, and improving the vaccination scheme and disinfection practices if needed.ConclusionsThe present study highlights the significance of coordinated PEDV management in infected farms to reduce the risk of recurrence and further contribute towards the national eradication of PEDV. 相似文献
75.
Aguinaga MA Gómez-Carballar F Nieto R Aguilera JF 《Journal of animal physiology and animal nutrition》2011,95(6):771-780
Sixteen pure-bred Iberian (IB) sows were used in two trials to determine the efficiency of utilization of milk protein and amino acid (AA) for growth in suckling piglets. It was hypothesized that there may be one or more strongly limiting essential AA (EAA) responsible for the slow rate of growth of the IB piglet. This AA will show the highest fractional retention. Daily milk yield and composition were determined weekly over a 34-day lactation period. Within each litter, one piglet at birth and four piglets on d 35 of life were slaughtered. The protein content of the IB sow milk was similar to that reported for conventional breeds. However, branched-chain AA, Thr, Pro, Asp and Ala were in concentrations somewhat below the range of literature values and Arg and Met, substantially above it. Milk intake per piglet tended to be greater in Trial 2 (832 vs. 893 g/day respectively; p = 0.066). However, the IB piglets grew at 168 ± 3.3 g/day, irrespective of the trial. The whole-body protein of piglets at weaning and the protein deposited in their body during the lactating period showed very close AA pattern. Among EAA, His and Arg show the highest fractional retentions (g AA retained/g AA ingested) in whole-body tissues (1.019 ± 0.025 and 0.913 ± 0.017 respectively) and also the highest body to milk ratios (1.50 and 1.41 respectively). Gly and Ala presented, among non essential AA, the highest efficiencies of utilization for tissue deposition (1.803 ± 0.057 and 1.375 ± 0.026 respectively) and body to milk ratios (2.75 and 2.12 respectively). These results suggest that the low efficiency of utilization of milk protein and the low rate of gain of the IB suckling piglet can be explained by a marked shortage in His supply, in addition to the suboptimal milk provision of Arg, Gly and Ala. 相似文献
76.
妊娠后期日粮中添加不同水平N-氨甲酰谷氨酸对母猪繁殖性能的影响 总被引:1,自引:0,他引:1
本试验研究了日粮中添加不同水平N-氨甲酰谷氨酸(N-carbamylglutamate,NCG)对妊娠后期母猪繁殖性能的影响,并对其作用机理进行初步探讨.选用妊娠80 d的长大母猪32头,随机分成4组(对照组和试验组1、2、3),每组8个重复.对照组饲喂基础日粮,试验组在基础日粮中分别添加0.04%、0.08%、0.12% NCG.母猪妊娠第110天采血分离血浆用于测定血浆游离氨基酸、NO、NOS、激素含量和血液生化指标.结果表明,母猪妊娠后期日粮中添加0.08%NCG比空白对照组窝产活仔数提高11.75%(10.75 vs.9.62,0.05<P<0.1),窝产活仔总质量提高13.23%(16.52 kg vs.14.59 kg,P<0.05),窝产死胎数降低57.14%(0.75 vs.1.75,P<0.05),降低了血浆尿素氮含量(P<0.05),同时提高了血浆精氨酸、NO、生长激素、锌离子浓度(P<0.05).日粮中添加0.04%和0.12% NCG也改善了母猪部分繁殖性能.上述结果表明,母猪妊娠后期日粮中添加NCG提高了母猪的繁殖性能,其作用机制可能是NCG有效提高了母猪内源精氨酸的合成,改善了母猪子宫内环境和胎猪营养供给,保证了胎猪的存活和生长. 相似文献
77.
北京市繁殖猪舍高温环境控制状况 总被引:8,自引:3,他引:5
高温是影响猪繁殖性能的重要环境因素。为了缓解北京市繁殖猪的热应激,于2009年对北京市猪舍的建筑类型、降温方式进行了调查,对常见猪舍外墙类型的隔热指标进行了计算评价,并对繁殖猪舍内温度进行了测试,结果表明:北京市猪舍建筑类型调查样本中,有窗封闭式、半开放式和温室大棚式猪舍的比例分别为74.0%、23.7%和2.3%;繁殖猪舍的降温方式中,通风降温和以水为媒介的降温方式各占50%左右;在现有猪舍外墙构造类型中,外贴聚苯板内砌砖的复合墙体的隔热性能最好。北京市夏季繁殖猪舍内温度与舍外变化趋势基本一致,多数时间内舍内温度高于舍外。最后,提出北京市目前繁殖猪舍的高温环境调控建议。 相似文献
78.
饲料中添加2%麦饭石对猪生产性能的影响 总被引:1,自引:0,他引:1
马如英 《青海畜牧兽医杂志》2011,41(4):27-28
试验结果显示:生产母猪饲料中添加2%麦饭石,母猪产仔成活率提高21.82%;猪育肥增重试验,断奶仔猪增重提高20.08%,提高饲料报酬34.21%:4月龄育肥猪增重提高18.38%,提高饲料报酬25.58%。 相似文献
79.
80.