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1.
High moisture corn (HMC) can undergo fermentation during storage that may improve its nutritional value for pigs. Stored HMC used in this study contained ( n = 4) 75% dry matter (DM), and, on a DM basis, 63.8% starch, 0.5% mono and disaccharides, 9.9% protein, 19 mM acetic acid, 18 mM lactic acid (LA), 1.25 × 10 7 cfu g − 1 of LA producing bacteria, 2.88 g kg − 1 total phosphorus (P), and 1.26 g kg − 1 soluble P. The soluble P content was higher than in freshly harvested HMC (0.27 g kg − 1 DM) and indicates P release during storage. Studies were aimed at altering the nutritional value of stored HMC by controlled fermentation or steeping. Changes in LA content were not affected ( P > 0.05) by addition of exogenous Lactobacillus and Bacillus bacteria. Steeping of HMC with phytase (Ronozyme) was examined at four inclusion levels (0, 500, 750, 1000 FTU kg − 1) and at either 21 °C or 37 °C. At 37 °C added phytase released virtually all phytate P within 6 h irrespective of the level (levels increased by 1.44 g P kg − 1 DM); at 21 °C, the increase was maximized at 1.2 g P kg − 1 DM after 24 h. The feeding value of HMC for pigs can be altered by steeping with exogenous phytase and does not appear to require microbial inoculants. 相似文献
2.
A new methodology based on (1) national data concerning livestock and rearing practices and (2) a mass-flow approach was developed to quantify ammonia (NH 3), methane (CH 4) and nitrous oxide (N 2O) emissions resulting from manure management in France. A literature review was performed to determine emission factors for each animal type and each management stage. A Microsoft Access® database containing these emission factors, the census data and manure compositions was then developed, allowing the calculation of gaseous emissions by the mass-flow approach. From this database, a national gas emissions inventory resulting from manure management was drawn up for the year 2003. Total NH 3 emissions were estimated at 382 kt N, mainly arising from cattle (72%). Greenhouse gas emissions were estimated at 14.0 Tg CO 2-eq. for N 2O and 10.2 Tg CO 2-eq. for CH 4. Most of the N 2O emissions occurred after the deposition of manure on soil during cattle grazing, while the CH 4 was mainly produced during the period where cattle manure remained in livestock buildings and in outside storage facilities. Moreover, an evaluation of the uncertainty was performed considering the standard deviation obtained for the emission factors. 相似文献
3.
We explored the applicability of the 13C bicarbonate dilution technique for determination of energy expenditure (EE) in young bulls in comparison to whole body indirect calorimetry (IC). Twelve bulls of a F2 German Holstein x Charolais cross (4.5 months, 332 ± 16 kg BM) received a diet providing 1000 kJ ME d − 1 kg BM − 0.75 and 4.3 g crude protein d − 1 kg BM − 0.75. Bulls were housed in respiration chambers and received an intravenous bolus of NaH 13CO 3 (A: 3 μmol kg BM − 1 ( n = 2), B: 7 μmol kg BM − 1 ( n = 4), C: 17.5 μmol kg BM − 1 ( n = 6), 99 at.% 13C) into the jugular vein to measure EE. Simultaneously, EE was determined by IC. After the 13C administration blood samples and breath gas were collected from the animals in the respiration chamber during a 24-h period (7.00–7.00 h). The recovery of 13C in breath CO 2 (% of 13C dose) was irrespective of NaH 13CO 3 dose (A: 69.7 ± 2.7%, B: 70.5 ± 4.5%, C: 75.0 ± 4.9%; P > 0.05). Only small amounts of 13C were excreted in urine (3.4 ± 2.6%) and feces (2.0 ± 1.3%). The EE determined by the 13C bicarbonate method using breath and blood 13C recovery rates as correction factors was not different from that measured by IC (816 ± 81 [blood] or 827 ± 101 [breath] vs. 820 ± 90 kJ d − 1 kg BM − 0.75). Bland–Altman analysis showed a 95% confidence interval for EE of ± 99 and ± 109 kJ d − 1 kg BM − 0.75 based on blood and breath 13C recovery, respectively. In conclusion, the 13C bicarbonate dilution method is appropriate to obtain reliable estimates of EE in young bulls using blood CO 2 or breath CO 2 under standardized experimental conditions, i.e. in the fasting state. 相似文献
4.
Animal welfare and environmental protection are increasingly important. Housing systems must be found that offer animal welfare while minimizing the overall emissions of ammonia and greenhouse gases. The straw flow system is an animal friendly housing system for fattening pigs, which can be operated economically on commercial farms. Emissions from conventional slurry based pig houses have been intensively studied, but more research is needed into straw based systems. In this study, we quantified emissions of ammonia and greenhouse gases from a straw flow system with or without daily removal of slurry to an outside store. The effect of applying a solid cover during outside storage was also examined. Emissions of NH3, N2O, CH4, and volatile organic C (VOC) from a commercial straw flow system for fattening pigs in Upper Austria were measured between June 2003 and March 2004. Emissions of CH4 during housing were 1.24 and 0.54 kg CH4 per pig place per year without and with daily manure removal, respectively. The corresponding N2O emissions amounted to 39.9 and 24.5 g N2O per pig place per year, and NH3 emissions to 2.10 and 1.90 kg NH3 per pig place per year without and with daily manure removal. Emissions of CH4, N2O and NH3, and of total greenhouse gases, from the straw flow system were lower than literature reference values for forced ventilated fully slatted floor systems. Daily removal of the manure to an outside store reduced emissions from the pig house. Emissions during storage of pig slurry derived from a straw flow system were quantified between June 2004 and June 2005. Slurry was stored in pilot scale stores with or without a solid cover and emissions quantified by a large open dynamic chamber. The solid cover reduced NH3 and greenhouse gas emissions by 30 and 50%, respectively. During cold climatic conditions stored pig manure emitted less NH3 and greenhouse gases than when stored under warm climatic conditions. We recommend the use of separate emission factors for slurry storage in the colder and warmer periods in the national emission inventory, and the use of covers on pig slurry stores. Overall, it is concluded that the straw flow system may combine recommendations of animal welfare and environmental protection. 相似文献
5.
Livestock production and ruminants in particular are an integral part of the organic mixed farming concept. In this paper, the feeding patterns of 26 organic dairy farms in two different regions in Germany are analysed, with particular emphasis on the amount and proportion of concentrates and purchased feed related to the dairy performance expressed per cow and hectare. Calculated on an energy basis (MJ NEL), the annual average milk yield of 6737 kg cow − 1 is derived from roughage (74%), concentrates and cobs (23%), and commercial processing by-products (e.g., spent grains) (3%). Per cow and year, 937 kg dry matter (DM) (range: 0–2724 kg) of concentrates are fed with an intensity of 135 g kg − 1 milk (range: 0–378 g kg − 1). Approximately 65% of the concentrates and commercial processing by-products are purchased. The area-related milk yield is almost 7000 kg ha − 1. For fodder production, 0.96 ha per cow is needed, of which 0.85 ha is farm land. The equivalent production area for purchased fodder is 0.11 ha. In the analysed region in northwestern Germany, most correlations between milk yield and analysed feeding parameters are close and significant. This is in contrast to the region in the south, where the variability of amount and proportion of the different feed types is predominantly independent of the milk yield. Intensification of dairy production to increase milk performance using a higher proportion of concentrates and purchased feed at some of the analysed farms needs to be carefully assessed according to the organic farming profile. 相似文献
6.
Twenty four Duroc × Landrace male piglets, aged 21 days, were assigned to 1 of 4 experimental diets. Diets 1 and 2 contained 150 g kg − 1 wheat bran and diets 3 and 4 contained 90 g kg − 1 maize cobs as the major fibre source. All diets contained 480 g kg − 1 wheat and 200 g kg − 1 soybean meal. Diets 2 and 4 were supplemented with the following enzyme complex: 800 U/kg cellulase, 1800 U/kg glucanase and 2600 U/kg xylanase. The replacement of wheat bran by maize cobs increased the acetic (P < 0.05) and decreased the butyric acid production (P < 0.05) in the cecum. Piglets fed diets with maize cobs had lower (P < 0.05) levels of butyric acid in the colon than those fed wheat bran. The xylanolytic, pectinolytic and cellulolytic enzyme activities were higher (P < 0.05) in the cecum and colon of piglets fed the wheat bran based diets. The supplementation of the diet with the enzyme complex did not significantly affect the levels of short chain fatty acids formed in the small intestine and there was a non significant increase of the levels of acetic, propionic and butyric acids in the cecum and colon of piglets (P < 0.10). No interactions were present between fibre sources and enzyme addition. The results suggest that the enzyme supplementation of the diet did not bring significant benefits to the animals and that when maize cobs replaces wheat bran in diets it negatively affects butyric acid production and fibre-degrading enzyme activity in the hindgut of piglets. 相似文献
7.
Forty multiparous cows (599 kg ± 18 kg BW) were fed with a basal diet (19.6% CP, 35% RUP, and 1.7 Mcal kg − 1 NEl) with alfalfa, corn silage and concentrate (49% forage: 52% concentrate). After calving, cows were randomly assigned to the treatments, which consisted in four levels of ruminally protected methionine (RPM): 0, 8, 16 and 24 g d − 1 of Mepron®M85 (Degussa Co.). Experiment was conducted for 120 days with measurements of milk production, composition, body weight, body condition score and DM intake every 15 days (3 consecutive days) starting on day 5 postpartum. Data were analyzed with the repeated measures model (four treatments in 8 periods through lactation). No treatment effects were detected on DM intake (20.38 ± 2.51 kg d − 1), body weight (599.78 ± 19.78 kg), body condition score (2.51 ± 0.19 units) and milk fat. However, milk production and protein yield were increased with addition of RPM ( P < 0.01). Milk production responded quadratically to methionine level. Holstein cows with a mean production of 35 kg d − 1 milk require addition of ruminally protected methionine (16 g d −1) to improve milk production. 相似文献
8.
为了减少畜禽粪便引发的恶臭气体污染,本研究选用具有除臭功能的贝莱斯芽孢杆菌、枯草芽孢杆菌、产朊假丝酵母和干酪乳杆菌4种微生物菌种作为Box-Behnke设计的4个因素,将4种菌种经活化后接入粪便中,以对应活菌数1×10 4、1×10 5和1×10 6 CFU/g作为Box-Behnke设计的3个编码水平。利用响应面设计构建得到29种复合微生物菌株组合,以其对猪粪中吲哚、氨和硫化氢的去除率作为参考指标,优化得到了4株除臭菌种的最优添加比例。结果表明,当菌液浓度为1×10 8 CFU/mL的贝莱斯芽孢杆菌、枯草芽孢杆菌、产朊假丝酵母和干酪乳杆菌分别以0.47%、0.05%、0.01%和1.00%的比例加入猪粪便中,堆积发酵7 d后对猪粪便中的吲哚、氨和硫化氢的去除率分别为73.59%、63.60%和70.29%。由此可见,经响应面设计优化后的除臭微生物菌种组合具有良好的除臭效果,对控制畜禽粪便恶臭污染具有较高的应用价值。 相似文献
9.
Two experiments were conducted to study the effects of growth hormone-releasing factor (GRF) and thyrotropin-releasing factor (TRF) administration on hormone concentrations in dairy cows. In the first trial, 12 cows were used on 5 consecutive days to determine the effect of four sc doses of GRF (0, 1.1, 3.3 and 10 μg•kg −1 BW) and three sc doses of TRF (0, 1.1 and 3.3 μg•kg −1 BW) combined in a factorial arrangement. GRF and TRF acted in synergy (P = .02) on serum growth hormone (GH) concentration even at the lowest dose tested and GH response to the two releasing factors was higher than the maximal response observed with each factor alone. TRF increased (P<.01) prolactin (Prl), thyrotropin (TSH), triiodothyronine (T 3) and thyroxine (T 4) concentrations similarly at the 1.1 and 3.3 μg•kg −1 doses and GRF did not interact (P>.40) with TRF on the release of these hormones. In the second trial, the effect of GRF (3.3 μg•kg −1 BW, sc) and TRF (1.1 μg•kg −1 BW, sc) was tested at three stages (18, 72 and 210 days) of lactation on serum Prl and TSH concentrations. Eighteen cows (n = 6 per stage of lactation) were used in two replicates of a 3 × 3 latin square. The TRF and GRF-TRF treatments were equipotent (P>.05) in increasing Prl and TSH concentrations. Prl and TSH responses were similar (P>.40) throughout lactation. In summary, GRF at doses ranging from 1.1 to 10.0 μg•kg −1 and TRF at doses ranging from 1.1 to 3.3 μg•kg −1 act in synergy on GH release and do not interact on Prl, TSH, T 3 and T 4 concentrations in dairy cows. Furthermore, Prl and TSH response to TRF are not affected by stage of lactation. 相似文献
10.
Phytases catalyse the hydrolysis of phytate rendering phosphorus (P) available for absorption. Endogenous plant phytases are to some extent present in cereals (depending on species and varieties) while microbial phytases are added to cereal based diets to increase the digestibility of phytate bound P. The present study compared two different microbial phytases. The basal diet was composed of wheat, barley, soybean and rapeseed meal without feed phosphate. The diet was initially expanded, pelleted at 90 °C and crumbled. Phytases were added at 250, 500 and 750 FTU kg − 1 diet ( Aspergillus niger; Phytase 1) and 375 and 750 FYT kg − 1 diet ( Peniophora lycii; Phytase 2). The experiment comprised 6 treatment groups of 6 pigs each kept in metabolism crates and fed one of the 5 test diets or a diet with no added microbial phytase. The diets were fed for 12 days, 5 days for adaptation and 7 days for total collection of faeces and urine. Phosphorus digestibility of the basal diet averaged 43% and increased to 55, 61 and 66% following addition of 250, 500 and 750 FTU/kg of Phytase 1 and 54 and 60% following addition of 375 and 750 FYT/kg of Phytase 2, respectively. In conclusion, equivalent effects were obtained when Phytase 2 was given at 1.5 times the doses of Phytase 1. 相似文献
11.
Smallholder farmers in Africa recognise the important role of manure in maintaining soil fertility. For smallholder farmers who use little fertiliser, efficient management of nutrients in manure is key for crop production. We describe a simple model to analyse the effect of manure management on the efficiency of mass and nutrient retention. We used on-farm data on manure excreted and manure management, experimental results, literature and fuzzy logic to model losses during manure storage. The model was used to analyse N cycling efficiency (NCE) within smallholder farms in western Kenya. Simulations showed that manure management during collection and storage had a large effect on the efficiency of C and nutrient retention. Differences in NCE between farmers of different wealth classes arose due to differences in resource endowment. For poorer farmers, large N losses occur at all stages of manure recycling. Urinary-N losses occurred on all farms but their impact on NCE for poor and medium-class farmers was larger due to the smaller amount of N recycled. With current management the poor farmer recovered < 1 kg N y − 1 in composted manure from 15 kg N y − 1 excreted. Improved manure storage had little effect on increasing overall NCE for the poor farmer due to large losses before storage. For the wealthier farmer improvement of manure storage increased NCE and allowed recycling of 30% of N excreted (ca. 30 kg N y − 1) with small investment in infrastructure. Covering manure heaps with a polythene film reduced mass and N losses considerably. For the poor to increase overall NCE, investment in cattle housing and recycling of urinary-N is required. Increasing cattle numbers or improved feeding would have a larger effect on manure availability but this is constrained by feed scarcity and investment capacity. The absolute amounts of N recycled (1–6, 4–17 and 7–18 kg N y − 1 for poor, medium and wealthier farmers) were small compared with maize N demand (> 50 kg N ha − 1), but significant given the small farm sizes (0.1–1.1 ha). Although absolute amounts of N recycled with improved manure management may have little immediate impact on crop productivity, manure is often the only input available. Manure provides other nutrients for crops and maintains soil organic matter — both vital to guarantee efficient use of fertiliser N — which justifies the search for interventions to assist farmers make better use of manure. 相似文献
12.
The effect of xylo-oligosaccharides (XOS), a probiotic culture of Saccharomyces cerevisiae (SC) and the combined administration of XOS and SC on the piglet intestinal microbiota was investigated. Twenty four weaned piglets were fed during 4 weeks with one of the following diets: (BD) basal diet; (BD + XOS) basal diet supplemented with xylo-oligosaccharides (20 g kg − 1); (BD + SC) basal diet supplemented with S. cerevisiae (6 × 10 9 CFU kg − 1); and (BD + XOS + SC) basal diet supplemented with xylo-oligosaccharides and S. cerevisiae. Samples from the ileum, caecum and colon were collected and analysed for total anaerobes growing in XOS or glucose, xylose and arabinose (GXA) containing media. Specific primers were used to evaluate differences in Bifidobacterium and Lactobacillus populations and ERIC PCR to fingerprint the intestinal microbiota. The lowest number of culturable bacteria was obtained from the ileum of animals fed BD + XOS. The highest PCR titres with Lactobacillus group-specific primers in BD and BD + SC were obtained in the caecal contents. In XOS-supplemented diets the PCR titres were increased or maintained, from the caecum to the colon. Bifidobacteria were not detected in any samples using genus-specific primers. In the dendrogram from ERIC PCR, the piglets fed with XOS diets presented the highest similarity between samples and probiotic reference strains. 相似文献
13.
Heat stability of commercial preparations of phytase has been of concern for quite some time, and efforts have been made to develop new preparations of this enzyme. A study was conducted to determine the stability of commercially available phytase product (granulate; Phytase A) and the new experimental product (powder; Phytase B). In the in vitro study, incubation of 100 mg of each of Phytase A and B with 200 μl of buffer for 2 min (30 s at desired temperature) resulted in 27.6 and 10.4% loss of activity at 60 °C and 80.6 and 53.9% at 70 °C, respectively. Both enzyme products were further subjected to steam pelleting in feed mills located in Manitoba and British Columbia. In the Manitoba study, the temperature of pellets as recorded at the discharge averaged 67 °C and was similar to that determined in British Columbia (70 °C). Under such temperatures, which may have been lower than the actual temperatures within the pellet mill, the loss of endogenous phytase activity averaged 58.5% (from 451 to 187 U kg − 1) and 42.5% (from 287 to 165 U kg − 1) in the two mills, respectively. Following correction for endogenous phytase activity, Phytase A and B recovery averaged 36.4 and 49.9%, respectively, at the Manitoba site and 44.1 and 49.4% at the British Columbia site. It appears evident from this study that the heat stability of enzyme (protein) per se rather than the granulation technology is a primary factor determining the stability of microbial phytase during steam pelleting. 相似文献
14.
The aim of this experiment was to study the effect of the application of pig slurry on potential pathogen (total and faecal coliform bacteria) presence in a Typic Xerofluvent soil. The experiment was conducted in field conditions, in the Segura River valley in the South East of Spain. Four treatments, in a fully-randomised design with three replicates per treatment, were established in experimental plots of 16 m 2 each. Fertiliser treatments were: MF, mineral fertiliser (with a complex 16N–16P 2O 5–16K 2O) equivalent to 150 kg N ha − 1; PSF, organic fertilisation with swine manure slurry, at two different rates (supplying 150 and 210 kg N ha − 1), and C, a controlled treatment without fertilisation. A high variability of the concentrations of total and faecal coliforms was observed during the experiment, mainly depends on the time and the treatment. The pig slurry amendment induced the highest initial and also persistent presence of total and faecal coliform bacteria. The higher application rate seemed to induce a long-lasting persistence of the total, but especially the faecal coliform, population in the amended soils compared to the lower rate. In most cases, an increase in the total coliforms content was observed in the soils amended with mineral fertiliser compared to controlled soils, probably due to an increase in soil microorganisms populations. In general, the total coliform bacteria was 2–3 log 10 units higher than the faecal ones. Mostly, a tendency to decrease with time was observed in both indicator microorganisms, in all the treatments. 相似文献
15.
Growth hormone (GH)-releasing factor (GRF) at concentrations of 10− 12 through 10− 7M for 6 hr linearly increased GH release (b 1 = 10.4 ± .3) from bovine anterior pituitary cells in culture. Maximum release of GH (262% above controls) occurred at 10− 7M GRF. In contrast, GH release-inhibiting factor (SRIF) at 10− 12 through 10− 5M had no effect on basal concentrations of GH. In a second experiment, as the proportion of SRIF relative to GRF increased. SRIF suppression of GRF-induced GH release from anterior pituitary cells increased. In a third experiment, anterior pituitary cells cultured in media containing fetal calf serum (FCS) were treated with cortisol (0 or 10 ng/ml media) for 24 hr before exposure to 10− 13 through 10− 7M GRF. GRF linearly increased GH secretion (b 1 = 7.4 ± .3) and cortisol augmented this response (b 1 = 10.5 ± .6). However, when cells were cultured in media containing dextran-charcoal treated FCS, cortisol did not alter GRF-induced GH release. Our results demonstrate that GH response of bovine anterior pituitary cells to GRF was modulated negatively by SRIF. However, augmentation of GRF-induced GH release by cortisol was evident only when cells were cultured in media supplemented with untreated FCS. 相似文献
16.
Three experiments were performed to study effects of decreased concentrations of estradiol-17β (E 2) on lifespan and function of ensuing ovine corpora lutea (CL). In experiment 1, 52 follicles were collected from 10 ewes and placed into individual culture with 0 or .01 μCi 3H-androstenedione (10 ng; 3H-A) and 0, 10 −11, 10 −9, 10 −7, or 10 −5 M of a nonsteroidal aromatase inhibitor, CGS16949A (CGS). Concentrations of E 2 secreted into the medium, and synthesis of estrogens as estimated by formation of 3H-water from 3H-A were decreased by 10 −5 and 10 −7 (P<.01), but not 10 −9 or 10 −11 M CGS. In experiment 2, luteolysis was induced in 24 ewes by injection of PGF 2 on days 5 to 10 of the estrous cycle (0 hr). Ewes received 0, 0.5, 1.0, 2.0 or 4.0 mg CGS per kg BW i.v. at −12, 0, 12 and 24 hr, and an ovulatory dose of hCG at 36 hr. Jugular (P<.001) and vena caval (P<.001) concentrations of E 2 were decreased by CGS at all doses tested for 8 to 10 hr, but had returned to levels similar to control ewes by the time of the next injection. Concentrations of E 2 around the time of the LH surge were similar in control and treated ewes. During the subsequent luteal phase, concentrations of progesterone (P 4) were similar in control and treated ewes. Thus, transient decreases in E 2 during the follicular phase were not deleterious to the subsequent luteal phase. In experiment 3, luteolysis was induced in 18 ewes by injection of PGF 2 on days 6 or 7 (0 hr) of the estrous cycle. Ewes received 0 or 1 mg CGS per kg BW i.v. every 8 hr from 0 to 40 hr. Ovulation was induced with hCG at 36 hr. CGS reduced jugular (P<.001) and vena caval (P<.001) concentrations of E 2, prevented an endogenous surge of LH (P<.05) and increased (P<.001) concentrations of FSH. All ewes had ovulated a marked follicle by 72 hr, but onset of the luteal phase, as assessed by concentrations of P 4, was delayed (P<.01) in ewes receiving CGS. Delayed luteal phases were not solely attributable to the presence of new CL or to luteinization of follicular cysts. When data were aligned according to the day ewes were observed in estrus, profiles of P 4 did not differ with treatment. Therefore, normal luteal function ensued following estrus whether or not ewes re-ovulated. In conclusion, decreased secretion of E 2 by the preovulatory follicle was not involved in the ontogeny of CL of short lifespan or subnormal function. Instead, adequate production of E 2 or precisely timed E 2 secretion may be required during follicular development for subsequent functional luteinization. 相似文献
17.
This study investigated the productive adaptability of pig breeds under different smallholder production conditions in Vietnam, comparing an indigenous with a Vietnamese improved breed. Fieldwork was conducted in four villages with different remoteness in North Vietnam from 2001 to 2002, in 64 households keeping the improved Mong Cai or indigenous Ban as sow breeds and progeny for fattening. Four visits per farm yielded 234 structured interviews. Reproductive performances were derived from 135 litters. Individual weights of pigs ( n = 755) were obtained. Data were analysed by regression, linear and generalised linear, especially loglinear models. Two distinct pig production systems were identified, that differed in remoteness, market access, resource availability, distribution of pig breeds and pig production intensity. Higher performances of 1.4 and 1.5 litters year− 1, 8.4 and 8.4 piglets weaned litter− 1, 66.6 and 93.0 kg piglets weaned sow− 1 year− 1, and 136 and 177 g day− 1 ADG were found in two villages near town with semi-intensive production conditions and a high rate of improved Mong Cai sows and MC and LW × MC offspring in the observed population. Lower performances of 1.1 and 1.1 litters year− 1, 4.6 and 5.5 piglets weaned litter− 1, 20.5 and 30.9 kg piglets weaned sow− 1 year− 1, and 66 and 85 g day− 1 ADG were observed in parallel to higher incidences of indigenous Ban pigs away from town under extensive conditions. Total live weight offtake per household per year was higher near town and in one village distant to town. MC and LW × MC remained even under demand-driven conditions below the performance potential reported for improved genotypes. Under resource-driven conditions with a saving-oriented production pattern, the higher-yielding but more demanding Mong Cai might not be an efficient production alternative as a further performance reduction can be assumed. A considerable live weight output was observed under resource-driven conditions and with a higher percentage of crossbred LW × Ban offspring in the population, possibly representing a promising production alternative. Factors influencing the performance expression of pigs, and the suitability of different methods for the assessment of performance parameters on-farm are discussed. 相似文献
18.
An experiment was conducted to examine the effect of dietary protein on the pathophysiology iof acute haemonchosis in Finn Dorset/Dorset horn lambs. Erythrokinetic and metabolic studies using 51Cr-red cells, 59Fe-trasferrin and 125I-albumine and digestive efficiency and nitrogen balance measurements wer conducted between 19 and 39 days after infection. Identical radioisotopic and nutritional studies were conducted later on pair-fed control lambs. The results demonstrated that lambs on a law protein diet (88 g crude protein (CP) kg−1 dry matter (DM)) were less able to withstand the pathyphysiological consequences of infection with 350 Haemonchus contortus larvae kg−1 body weight than lambs given a high protein (170 g CP kg−1 DM) diet, despite similar worm budens. Erythrokinetic studies indicated that abomasal blood loss was similar in both groups of infected lambs, and circulating red cell volumes were reduced and plasma volumes were expanded to a similar degree in both groups. The majority of infected lambs in both dietary groups responded equally well to the gastric haemorrhage by increasing the rate of red cell production and their absorption of dietary iron was greater than in the control lambs. Albumin catabolism was increased in both groups of infected lambs, particularly in those given the low protein diet. Within each dietary group there were no differences in the digestibilities of the various proximate fractions of the experimental diets and no differences in the urinary of faecal nitrogen losses between infected lambs and their pair-fed control. However, loss of appetive was a major feature of the disease, particularly in the lambs given the low protein diet and this feature appeared to be crucial in determining the ability of the infected sheep to withstand the pathophysiological effects of the parasite. 相似文献
19.
DNDC(denitrifiction-decompostion)模型是以生物地球化学进程为基础模拟碳氮循环的模型,被广泛用来预测稻田温室气体的排放,但利用DNDC模型研究苜蓿绿肥对稻田生态系统的相关研究尚未见报道。因此,本研究结合两种绿肥在上海地区的使用,模拟了4个不同处理:对照(未施氮肥和绿肥)、氮肥(200 kg/hm 2)、紫花苜蓿绿肥(3000 kg DM/hm 2)+氮肥和蚕豆绿肥(3000 kg DM/hm 2)+氮肥,研究苜蓿绿肥对水稻产量和稻田温室气体排放的影响,同时,对DNDC模型进行本地化修正,建立适宜我国长江中下游地区绿肥-水稻轮作生态系统的DNDC模型,结果表明,与对照相比,苜蓿、蚕豆和氮肥处理下的水稻产量分别提高了41.85%,29.81%和25.36%;蚕豆绿肥处理下的CH 4排放量高于苜蓿绿肥处理,温室气体的排放强度在苜蓿绿肥处理下未显著提高。通过对DNDC模型多个参数的调整和模拟,DNDC模型对水稻产量和CH 4排放的模拟值与实测值十分接近,其中,水稻产量实测值和模拟值的决定系数R 2为0.89,相对平均误差RMD为-0.8%。大气温度、大气CO 2浓度、土壤有机碳和土壤粘粒对稻田CH 4和N 2O排放十分敏感,其中,大气温度、CO 2浓度和土壤有机碳与CH 4和N 2O的排放强度呈显著的正相关关系,而土壤粘粒与CH 4排放呈显著的负相关关系,本研究结果说明本地化改进的DNDC模型能够准确模拟紫花苜蓿绿肥对水稻产量和稻田温室气体排放的作用效果。 相似文献
20.
Manure management systems are conducive to nutrient and carbon losses, but the magnitude of the loss highly depends on the nutrient element, the manure management system and the environmental conditions. This paper discusses manure management systems in the 27 Member States of the European Union (EU-27) and nutrient losses from these systems, with emphasis on nitrogen (N). In general, losses decrease in the order: C, N >> S > K, Na, Cl, B > P, Ca, Mg, metals. Assessments made with the integrated modeling tool MITERRA-EUROPE indicate that the total N excretion in 2000 by livestock in EU-27 was 10,400 kton. About 65% of the total N excretion was collected in barns and stored for some time prior to application to agricultural land. Almost 30% of the N excreted in barns was lost during storage; approximately 19% via NH 3 emissions, 7% via emissions of NO, N 2O and N 2, and 4% via leaching and run-off. Differences between Member States in mean N losses from manure storages were large (range 19.5–35%). Another 19% of the N excreted in animal housing systems was lost via NH 3 emissions following the application of the manure to land. The results indicate that maximally 52% of the N excreted in barns was effectively recycled as plant nutrient. Various emission abatement measures can be implemented and have been implemented already in some Member States to reduce the emissions of NH 3 and N 2O, and the leaching of N and P. There is scope to reduce NH 3 emissions by 30% relative to the reference year 2000, although the uncertainty in estimated emissions and in the estimated effects of emission abatement measures is relatively large. 相似文献
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