The response to N fertilization of a short-duration pigeonpea genotype, ICPL 87, was studied in the field to assess the scope for genetically improving symbiotic N2 fixation by pigeonpea. The field study was undertaken during 1985, 1986 and 1987 growing seasons on Vertisol and Alfisol at ICRISAT Center (peninsular India), Inceptisol at Gwalior (central India) and Entisol at Hisar (northern India) in as non-limiting environmental conditions as possible. Nitrogen fertilizer was applied to the soil at various growth stages to determine when N becomes most limiting. There was a significant response in grain yield to fertilizer N applied at flowering in Vertisol but not in Alfisol, Inceptisol or Entisol. This suggests that biological N2 fixation by short-duration pigeonpea was not adequate to meet N requirements of the crop grown in Vertisol but that it was probably adequate in the other three soil types. These results are discussed in relation to the nodulation and acetylene reductase activity of pigeonpea and also N mineralization potential of different soils. It can be concluded that there is a need for genetic improvement of N2 fixing ability of short-duration pigeonpea grown on heavy textured soils such as Vertisols. 相似文献
The objective of this study was to determine how interactions between dietary ruminally degradable protein (RDP) level and ruminally fermentable carbohydrate (RFC) alter urea N transfer to the gastrointestinal tract (GIT) and the utilization of this recycled urea N in rapidly growing lambs fed high-N diets. Four Suffolk ram lambs (34.8 +/- 0.5 kg of BW) were used in a 4 x 4 Latin square design with 21-d periods and a 2 x 2 factorial arrangement of dietary treatments. The dietary factors studied were 1) dry-rolled vs. pelleted barley as the principal source of RFC and 2) dietary levels of RDP of 60 vs. 70% (% of CP). All diets contained 28.8 g of N/kg of DM. Experimental diets were composed of 80% concentrate mixture and 20% barley silage (DM basis) and were fed twice daily at 0900 and 1700 as total mixed rations. Nitrogen balance was measured from d 15 to 20, and urea N kinetics were measured from d 15 to 19 using intrajugular infusions of [(15)N(15)N]-urea. Nitrogen intake (P = 0.001) and fecal (P = 0.002) and urinary (P = 0.03) N excretion increased as dietary RDP level increased, but the method of barley processing had no effect. Feeding dry-rolled compared with pelleted barley (P = 0.04) as well as feeding 60% RDP compared with 70% RDP (P = 0.04) resulted in a greater N digestibility. Whole-body N retention was unaffected (P >/= 0.74) by dietary treatment. Dietary treatment had no effect on endogenous production of urea N and its recycling to the GIT; however, across dietary treatments, endogenous production of urea N (45.8 to 50.9 g/d) exceeded N intake (42.3 to 47.9 g/d). Across dietary treatments, 30.6 to 38.5 g/d of urea N were recycled to the GIT, representing 0.67 to 0.74 of endogenous urea N production; however, 0.64 to 0.76 of urea N recycled to the GIT was returned to the ornithine cycle. In summary, although dietary treatment did not alter urea N kinetics, substantial amounts of hepatic urea N output were recycled to the GIT under the dietary conditions used in this study, and additional research is required to determine how this recycled urea N can be efficiently captured by bacteria within the GIT. 相似文献
Previously reported cases of congenital cutaneous mast cell tumours in calves were characterized by multiple discrete nodules. The calf presented herein is, to the authors' knowledge, the first documented case of congenital diffuse cutaneous mastocytosis. The entire skin was thickened and wrinkled with particularly prominent skin folds on the head, ventrum, and legs. Histological examination of two haired skin specimens (eyelid, muzzle margin) revealed that the dermis was diffusely infiltrated by sheets of neoplastic mast cells. 相似文献
The economic and performance effect of supplementing smallholder cattle by substituting commercial feed with iso-nitrogenous and iso-energetic diets based on alternative protein sources was investigated in two trials. In trial 1, three diets (commercial concentrate, commercial concentrate partially substituted with mucuna, and commercial concentrate partially substituted with lablab–cowpea) compared with veld grass were allocated to 12 cattle in a complete randomised block design. In trial 2, a double complete randomised block design with 40 cattle assigned to four forage legume-based diets, a poultry-based diet and a commercial beef concentrate was carried out. Diets were offered at 1.5% of body weight daily over 56 d. Average daily weight gain (ADWG) was measured weekly in trial 1 and fortnightly in trial 2. In trial 1, ADWG was significantly (p < 0.05) higher for animals on supplements compared with non-supplemented cattle. In trial 2, ADWG was significantly highest on the groundnut stover-based diet and least on the poultry litter diet. Supplementation had a positive effect on ADWG and economic performance of smallholder beef cattle. Substitution of commercial concentrates with alternative protein sources reduced diet costs and significantly improved gross margins. 相似文献
A study was conducted to compare conception rates in 71 Tuli and 86 Afrikander beef cattle bred using either artificial insemination (AI) or the bull. Animals were bred using either artificial insemination or natural service at Matopos Research Station. Animals were grouped into three groups of heifers (parity 0; P0), second calvers (parity 1; P1) and mature cows (parity 2; P2) before being randomly assigned to one of the two breeding methods. A binary logistic regression was used for statistical analysis where breeding method (AI vs natural service) was the treatment factor and conception rate was the measured response while breed, parity and last calving date were non-treatment factors. No significant differences were observed in conception rates between breeds (P > 0.05). However, the method of breeding animals, parity and calving interval affected (P < 0.05) conception rates. The breeding method, parity and calving interval had a positive Kendall’s tau-b correlation coefficients to conception. More animals were pregnant when AI (77.6%) was used compared with natural mating (56.79%). Conception rates were significantly lower (P < 0.05) in C1 compared with C2 cattle. The odds ratio for breeding method and parity are positive and significant (P < 0.05). In conclusion, the study confirms that artificial inseminated animals had similar conception rates to naturally serviced animals for both Tuli and Afrikander breeds. As such, artificial insemination technology can be used to complement or substitute natural service in indigenous cattle’s of Zimbabwe.
Land-use changes can modify soil carbon contents. Depending on the rate of soil organic matter (SOM) formation and decomposition, soil-vegetation systems can be a source or sink of CO2. The objective of this study was to determine the influence of land-use change on SOM distribution, and microbial biomass and respiration in an Andisol of the Chilean Patagonia. Treatments consisted of degraded natural prairie (DNP), thinned and pruned Pinus ponderosa plantations (PPP), and unmanaged second-growth Nothofagus pumilio forest (NPF). The soil was classified as medial, amorphic, mesic Typic Hapludands. Soil microbial respiration and microbial biomass were determined in the laboratory from soil samples taken at 0–5, 5–10, 10–20 and 20–40 cm depths obtained from three pits excavated in each treatment. Physical fractionation of SOM was performed in soil of the upper 40 cm of each treatment to obtain the three following aggregate-size classes: macroaggregates (>212 μm), mesoaggregates (212–53 μm) and microaggregates (<53 μm). Plant C content was 68% higher in PPP than in DNP and 635% higher in NPF than in PPP. Total soil and vegetation C content in both DNP and PPP were less than half of that in NPF. Total SOC at 0–10 cm depth decreased in the order DNP (7.82%) > NPF (6.16%) > PPP (4.41%), showing that land-use practices affected significantly (P < 0.01) SOC stocks. In all treatments, microbial biomass C and respiration were significantly higher (P < 0.05) in the upper 5 cm. Soil microbial respiration was also correlated positively with microbial biomass C and SOC. The different land uses affect the formation of organic matter, SOC and microbial biomass C, which in turn will affect soil microbial respiration. Conversion of DNP to PPP resulted in a 44% decrease of SOC stocks in 0–10 cm mineral soil. The largest amount of SOC was stabilized within the mesoaggregate fraction of the less disturbed system, NPF, followed by PPP. In the long term, formation of stable mesoaggregates in soils protected from erosion can behave as C sinks. 相似文献
This study was undertaken to measure certain carbon (C) fluxes in a Pinus ponderosa-based silvopastoral systems (SPS) in Patagonia, Chile. Results are compared to those from adjacent 18-year-old managed pine plantations (PPP) and natural prairie (PST). Litter decomposition was determined using the litterbag method. Leached soil solution was collected with tension lysimeters at 80 cm depth, and soil respiration evaluated in situ with the soda lime technique. Wind direction influenced the litterfall distribution in SPS, with 94 % falling in the tree strips and within 3 m on the east side. In the first 6 months the initial needle decomposition was low and less than 5 % of the initial mass. The overall soil organic carbon (SOC) and N contents (0–40 cm depth) decreased significantly in the order SPS > PST > PPP, and within SPS were greater in the alleys, starting at 2.5 m from the tree strip, with the highest values always eastward of the strip, suggesting influence by the wind direction. Total soil respiration decreased in the order PST > SPS > PPP and leached C decreased in the order PPP > PST > SPS. In general, the mean annual soil moisture in the pasture alleys of SPS was twice that of PST. The air/soil temperatures decreased significantly in the second year only in PST and at 2 m and beyond from the tree strip in SPS. Soil moisture varied significantly among treatments, but showed the strong influence exerted by trees in the creation of a favorable microclimate within the pasture alleys of SPS. 相似文献
To access the process of nitrogen mineralization in soil, the buried-bag technique was used among traditional agroforestry systems in the Bhabhar belt of Kumaun Himalaya. The present study, determined the relationship between various parameters of N-mineralization with agroforestry systems, seasons and soil depths. Season and soil depth have significantly (p?<?0.001) affected the process of ammonification, nitrification and net N-mineralization. The soil ammonium-N pool was comparatively higher than the nitrate-N pool. Highest amount of ammonium and nitrate-N were recorded in the agri-horticulture (AH) system, and lowest in the agri-horti-silviculture (AHS) system. Among the systems, highest amount of inorganic-N (ammonium?+?nitrate) was recorded during rainy season while, lowest during winter season. The highest ammonification rate (6.47?±?1.47 mg kg?1 month?1) was observed in agri-silviculture system and lowest (5.67?±?1.68 mg kg?1 month?1) in AHS system, while nitrification value was maximum (2.53?±?0.40 mg kg?1 month?1) in AH system and minimum (2.23?±?0.37 mg kg?1 month?1) in AHS system. The values of net N-mineralization were ranged from 4.03?±?0.53 to 13.29?±?0.44 mg kg?1 month?1. The values of inorganic-N and net N-mineralization were significantly more (P?<?0.01) in the surface soil layer (0–20 cm) than the subsurface layers (20–40 cm and 40–60 cm). Nitrogen mineralization was negatively correlated with the soil pH and positively correlated with soil organic carbon and total soil nitrogen. Higher rate of N-mineralization in AHS system indicated rapid turnover of nitrogen due to soil management practices and suggested that the changes in agroforestry based land-use systems alter the process of net N-mineralization, nitrification and ammonification.
Variance components for production traits were estimated using different models to evaluate maternal effects. Data analysed were records from the South African pig performance testing scheme on 22 224 pigs from 18 herds, tested between 1990 and 2008. The traits analysed were backfat thickness (BFAT), test period weight gain (TPG), lifetime weight gain (LTG), test period feed conversion ratio (FCR) and age at slaughter (AGES). Data analyses were performed by REML procedures in ASREML, where random effects were successively fitted into animal and sire models to produce different models. The first animal model had one random effect, the direct genetic effects, while the additional random effects were maternal genetic and maternal permanent environmental effects. In the sire model, the random effects fitted were sire and maternal grand sire effects. The best model considered the covariance between direct and maternal genetic effects or between sire and maternal grand sire effects. Fitting maternal genetic effects into the animal model reduced total additive variance, while the total additive variance increased when maternal grand sire effects were fitted into the sire model. The correlations between direct and maternal genetic effects were all negative, indicating antagonism between these effects, hence the need to consider both effects in selection programmes. Direct genetic correlations were higher than other correlations, except for maternal genetic correlations of FCR with TPG, LTG and AGES. There has been direct genetic improvement and almost constant maternal ability in production traits as shown by trends for estimated (EBVs) and maternal breeding values (MBVs), while phenotypic trends were similar to those for EBVs. These results suggest that maternal genetic effects should be included in selection programmes for these production traits. Therefore, the animal–maternal model may be the most appropriate model to use when estimating genetic parameters for production traits in this population. 相似文献
