Toposequential Variation in Soil Fertility and Rice Productivity of Rainfed Lowland Paddy Fields in Mini-Watershed (Nong)in Northeast Thailand

Abstract

Mini-watersheds called Nongin Thai are geographical components of rainfed lowland rice culture in Northeast Thailand, and constitute distinct units in understanding environmental constraints for low and unstable rainfed rice production there. The toposequential variation of soil fertility and its relation to rice productivity within mini-watersheds, was examined by phytometry of sampled soils and field measurements of rice growth and yield. The phytometry experiment with irrigated potted rice using soils sampled from various rice fields within each mini-watershed, revealed that soil fertility as evaluated by rice dry matter production showed a 5 times difference among the fields at most. The difference in the soil fertility was ascribed primarily to that in nitrogen (N) supply capacity, which itself had a strong correlation with soil organic carbon (SOC) content. Accordingly, the biomass production of pot-grown rice was proportional to SOC. content, which suggested the usefulness of SOC as an index for soil fertility evaluation. The effect of clay on the soil fertility was much less than that of SOC. The actual rice yield in each field also showed quite large field-to-field variation, most of which was explained by the SOC content, rice growth duration and fertilizer application rate even though water availability also affected the yield. The yield positively correlated with growth duration and hence with earlier transplanting. Both SOC and clay contents of fields showed steep gradients with ascending field elevation within mini-watersheds, resulting in a marked toposequential distribution of rice yield. The toposequential distributions of SOC and clay contents imply that rice culture after deforestation accelerated soil erosion from upper to lower fields. The large toposequential gradient in soil fertility requires different resource and crop management for each toposequential position, in order to improve rice productivity of the mini-watershed as a whole.     

土壤肥力对高产小麦品种烟农1212旗叶叶绿素荧光特性和产量的影响

为了解土壤肥力对小麦旗叶叶绿素荧光特性和籽粒产量的影响,以高产小麦品种烟农1212为材料,比较分析了常年小麦产量水平为12 000和9 000kg·hm-2的高低两种土壤肥力条件下麦田土壤贮水消耗量、小麦旗叶叶绿素含量、叶绿素荧光参数、叶面积指数和籽粒灌浆速率的差异。结果表明:(1)高肥力下小麦全生育期60～100cm土层土壤贮水消耗量显著高于低肥力。(2)相对于低土壤肥力,高土壤肥力显著增加了小麦旗叶开花后21～35d的叶绿素相对含量和实际光化学效率(ΦPSⅡ)、开花后28d和35d的最大潜在光化学效率(Fv/Fm)、光化学猝灭系数(qp)以及开花后14～35d相对电子传递速率(ETR)。高土壤肥力下小麦在孕穗期、开花期、开花后21～35d具有较高的叶面积指数。(3)高土壤肥力可显著提高灌浆中后期的籽粒灌浆速率,显著增加籽粒产量及其构成因素、水分利用效率和氮肥偏生产力。由此可见,高土壤肥力能够改善小麦光合能力,有利于产量形成,进而提高产量和促进水肥高效利用。     

Artificial insemination in pigs: predicting male fertility

Efficient artificial insemination (AI) is essential for future challenges in the pig industry. Knowledge on the exact relation between semen quality characteristics and fertility can have a major impact on both the genetic merit of future animals and the efficiency of AI. Variation in fertility is caused not only by farm- or sow-related parameters but also by boar- and semen-related parameters. In pig AI there is no gold standard concerning semen quality assessment. Assessing semen quality characteristics objectively and relating them to large field fertility datasets leads to an efficient production of insemination doses, which results in an efficient dissemination/descent of the breeding program required genes. Overall, this contributes to the development of semen quality assessments, which improves the prediction of porcine male fertility. Knowing which semen characteristics, and to what extent, contribute to male fertility and makes the field fertility more predictable.     

LRH-3、PMSG、HCG对人工授精母蓝狐产仔效果影响的比较(Ⅲ)

通过PMSG +LRH - 3和PMSG +HCG的组合使用 ,结果表明 ,使用PMSG +LRH - 3的试验组母狐的产仔率比对照组提高了 2 0 % ,胎平均产仔数提高了 0 2只。而使用PMSG +HCG组合母狐的产仔率与对照组相同 ,但胎平均产仔数提高了 0 5只。     

兽用繁殖控制疫苗研究现状

兽用繁殖控制疫苗研究发展迅速,本文阐述了兽用繁殖控制疫苗的研制以及抑制生殖激素的疫苗、抗配子抗原疫苗、增加受精率的疫苗等方面的研究现状,并介绍了相关的商品化产品。     

Multiple trait genetic evaluation of ewe traits in Icelandic sheep

The prolificacy of the ewes was measured as the number of lambs born per ewe mated (NLB) when the ewes were 1–4 years of age. The ewe productivity related to the same age interval was measured by special ewe production indices (EPI). The genetic parameters for these traits were estimated by a series of bivariate REML analyses using animal models. The material used for the genetic analysis contained records on 193 213 ewes. The heritability estimates for NLB were h² = 0.17, 0.13, 0.11, 0.10 for the four respective age classes. Corresponding estimates for EPI were h² = 0.16, 0.17, 0.17, 0.15. The genetic correlations among NLB at different ages ranged from 0.63 to 0.98 and among EPI from 0.82 to 0.99. The genetic correlations between NLB and EPI were generally low. The material used for estimating the breeding values by the MT‐BLUP Animal Model consisted of 1.5 million individuals in the pedigree file. In total 815 782 ewes had records for the NLB and 763 491 ewes had production index (at least 1 year). The records were registered in the years 1990–2006. All possible missing patterns were present in the data. In the iteration process expected values for missing traits were generated and solutions were obtained on canonical transformed scale. The genetic evaluations were run independently for NLB and EPI for computational convenience given the correlations between these traits were negligible.     

Supplementing a skimmed milk–egg yolk-based extender with L-carnitine helps maintain the motility,membrane integrity and fertilizing capacity of chilled ram sperm

This study examines the effect of L-carnitine (LC) on chilled ram semen stored for up to 96 hr. Semen samples were collected, placed in a skimmed milk + 6% egg yolk extender, pooled, aliquoted and diluted with the same extender supplemented with different LC concentration: 0 (control), 1 mM (LC1), 2.5 mM (LC2.5), 5 mM (LC5), 7.5 mM (LC7.5) or10 mM (LC10). Sperm kinetics and membranes (plasma, acrosome and mitochondrial) were examined using the CASA system and triple fluorescence staining (PI/ PNA-FITC/Mitotracker). The progressive motility was greater (p < .05) with LC7.5 treatment than the control sperm at 96 hr. The curvilinear velocity (p < .01) and the percentage of sperm with intact membranes (plasma/acrosome/mitochondria) (p < .01) were greater with all LC treatments than the control group at all times. Straight line velocity was greater (p < .01) with LC5 and LC7.5 treatments than the control group after 48 hr. The LC5 group also returned lower ALH values (p < .05) than these seen for the control groups after 48 hr. The fertilizing capacity of LC5 samples stored at 15°C for 2 hr (LC5-15°C-2h) and at 5°C for 24 hr (LC5-5°C-24h) was tested in three ewe groups via cervical fixed-time artificial insemination. In two groups, the fertilizing capacity of the LC5-5°C-24h was reduced (p < .001). In the remaining group, however, no significant difference was seen between the LC5-15°C-2h and LC5-5°C-24h sperm in this respect (pregnancy rates 52.4% versus 42.8%; p > .05). Overall, the present results suggest that supplementing skimmed milk–egg yolk-based extenders with LC has a positive effect on chilled sperm variables and fertilizing capacity.     

Supplementing rumen‐protected methionine to lactating multiparous dairy cows did not improve reproductive performance

There is evidence that supplementing methionine has positive effects on uterine environment, oocyte quality and embryo development in cattle. Thus, the objective of this study was to evaluate reproductive traits of cows supplemented with rumen‐protected methionine (RPM) during early to mid‐lactation in comparison with an untreated control group (CON). An additional focus was on the effect of puerperal diseases on reproductive performance parameters in RPM‐supplemented group MET and in CON. A total of 1,709 multiparous Holstein‐Friesian cows were enrolled in this field trial conducted on a commercial dairy farm in Slovakia. Cows were allocated at approximately 12 days post‐partum (dpp) to either CON or MET, the latter supplemented with 25.0 g–27.2 g RPM per cow per day incorporated into the total mixed ration (TMR) until leaving the study pen at approximately 140 dpp. The amount of RPM was calculated based on individual feed ingredients analysis and adjusted during the study period when TMR changed. Cows were monitored during the post‐partum period by vaginal examination (day 5 pp), measuring of beta‐hydroxybutyrate in blood (3, 5, and 8 dpp) and by vaginal examination, uterine cytology and measuring of back fat thickness by ultrasound (all at 31 ± 3 dpp). Compared with CON, cows supplemented with RPM did not show better reproduction performance parameters (first service submission rate, days to first service, conception risk, days open 140). Results from binary logistic regression model for the risk of conception showed that metritis had a significant effect, but the supplementation of methionine had not. Results of Cox regression analysis for the odds of conception within 140 dpp revealed only metritis and clinical endometritis as significant factors. In conclusion, supplementation of RPM had no beneficial effect on reproductive performance in this study farm compared with an untreated control group.     

甘肃省不同区域人工草地土壤肥力特征研究

以甘肃省不同区域人工草地土壤样品为研究对象,测定12个不同区域[民乐县(ML1、ML2)、安定区(AD)、通渭县(TW1、TW2、TW3、TW4)、宁县(NX1、NX2)、靖远县(JY1、JY2、JY3)]人工草地土壤的pH值、有机质、全氮、速效磷、速效氮、速效钾。结果表明:AD的p H值最大,JY3的pH值最小;TW2有机质含量最高,AD有机质含量最低,TW2较AD提高了78.95%,在TW2种植陇东苜蓿对土壤有机质影响大;TW2、TW3速效氮含量较高,约为AD速效氮含量的3倍,在TW2、TW3种植陇东苜蓿对土壤速效氮影响大;JY2速效钾含量是AD的3倍,TW2速效钾的含量最低,在JY2种植陇东苜蓿对速效钾影响大;ML1、ML2速效磷含量较高,NX1、NX2速效磷含量较小,在NX1、NX2种植陇东苜蓿对土壤速效磷影响小;TW2全氮含量最高,较AD提高了85.07%,在TW2种植陇东苜蓿对土壤全氮影响大。综合分析结果显示,TW2土样的关联度值最大(0.787 9),综合肥力最好,为最优土样;NX2土样的关联度最小(0.500 7),综合肥力最差。     

Effect of peripartal administration of mycobacterium cell wall fraction on health and fertility of Holstein cows under organic-certified management

The main objective of this study was to evaluate the effect of peripartal administration of a commercially available nonspecific immune stimulant (mycobacterium cell wall fraction; MCWF [Amplimune, NovaVive Inc., Napanee, ON, Canada]) on the incidence of disease during early lactation and subsequent fertility of dairy cows. A second objective was to characterize the dynamics of circulating white blood cells (WBC) and metabolic markers following treatment administration. Cows in an United States Department of Agriculture (USDA) organic-certified dairy herd were blocked by parity and, based on sequential calving dates, randomly assigned to receive two injections (5 mL s.c.) of either a placebo (saline solution) as a control (CON; n = 71) or MCWF (n = 65) at enrollment (7 d before expected calving) and within 24 h after calving. Blood samples were collected from a subsample of the study population (MCWF = 16; CON = 18) for WBC count at enrollment, at day 2 post enrollment, and at days 1, 3, 7, and 14 after calving. Serum fatty acids, beta-hydroxybutyrate, and Ca concentrations were determined at days 1 and 7 postpartum (MCWF = 21; CON = 21). Main outcome variables included incidence risk of peripartal and early lactation health disorders and pregnancy at first artificial insemination (AI), at 100, and at 150 days in milk (DIM). In addition, the average daily milk yield up to 90 DIM and death and live culling before 305 DIM were compared. Treatment effects were assessed using multivariable logistic regression, time-to-event analyses, and repeated measures analysis of variance (ANOVA). A treatment effect on the incidence risk of some of the health disorders in the study was established. Incidence risk of metritis and clinical mastitis <28 DIM was smaller in MCWF than in CON cows (36.9% vs. 50.7% and 6.3% vs. 19.7%, respectively). On the contrary, the incidence risk of respiratory disease <28 DIM was smaller in CON (0%) than in MCWF (7.7%). Reproductive performance of multiparous cows was affected by MCWF administration: pregnancy at first AI and pregnancy at 100 and 150 DIM were greater in MCWF than in CON (35.6% vs. 19.2%; 51.1% vs. 25.0%; and 64.4% vs. 40.4%, respectively). Overall, median intervals from calving to pregnancy were 90 vs. 121 d in MCWF and CON cows, respectively. No treatment effects on the dynamics of circulating WBC or in postpartum metabolic status were established. No differences for milk yield or for the proportion of cows that survived up to 305 DIM were determined, although cows in MCWF left the herd earlier than cows in CON. In conclusion, incidence risks of metritis and mastitis in early lactation were smaller in cows receiving MCWF, whereas the incidence risk of respiratory disease was smaller in CON. Fertility significantly improved in MCWF compared with CON cows. As this study was performed in an organic-certified dairy, specific health and reproductive management practices may affect the external validity of the current findings.