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《养殖与饲料．饲料世界》2016,(7)
山羊品种的好坏直接决定了羊的生产性能、饲料报酬、饲养周期、料肉比等,而圈舍育肥是提高商品肉山羊及其产品品质的有效途径之一,能显著提高养羊经济效益。本文介绍了肉山羊父母本的品种选育、商品肉山羊的圈舍育肥和相关的饲养管理技术。 相似文献
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在迄今尚无肉山羊生产系统理论和完整技术的情况下，本文从制约肉山羊生产的“品种、环境、社会”三方面的因素，提出了在我国山丘区农村条件下，提高肉山羊生产水平的途径，旨在合理利用资源、促进肉山羊生产的发展。 相似文献
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由于人们生活水平的提高，对羊肉的需求逐渐增大，但由于山羊品种个体小、生长速度慢、产肉能力差等原因制约着肉丰业的发展，难以满足人们对羊肉日益增长的需求．为了提高山羊品种的产肉能力，可采取放牧加合饲，当年羔当年出栏，引入肉羊品种改良本地山羊等措施提高山羊产肉能力．现将提高山羊产肉能力及经济效益的措施浅述如下．1利用经济杂交，提高山羊产肉能力由于本地山羊体格小，产肉能力差，可以引人肉用型品种，通过与本地山羊杂交，提高本地山羊的产肉性能．如我市1997年从陕西省畜牧所引人肉用型波尔山羊冷冻颗粒在新郑市改良本… 相似文献
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随着人们生活水平的提高,对羊肉的需求逐渐增多,但由于山羊品种个体小、生长速度慢、产肉能力差等原因制约着肉羊业的发展,难以满足人们日益增长的对羊肉的需求。为了提高山羊的产肉能力,可采取放牧加舍饲、当年羔当年出栏,引入肉羊品种杂交改良山羊等措施提高山羊产肉能力。现将提高山羊产肉能力及经济效益的措施总结如下。 相似文献
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波尔山羊是目前世界上最优秀的肉用山羊品种,其突出优点是繁殖力高,生长发育快,产肉力、屠宰率、净肉率高,肉的品质好,与国内本地山羊杂交后杂种优势明显,经济效益显著。由于引入数量有限,价格高,不能大量利用本交进行杂交改良,使 相似文献
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During different stages of lactation, different requirements of calcium have to be met depending on the milk amount. Vitamin D receptors (VDR) regulate calcium homeostasis by increasing the entry of Ca into blood from bone stores and dietary sources. The purpose of this study was to investigate if age and breed of cows influence VDR amounts across different segments of the gastrointestinal tract. Thirty-six cows were used (18 Brown Swiss, 18 Holstein Friesan, both > 5.5 years or < 4.5 years). Tissue specimens of the intestines were collected from the cows. Formaldehyde-fixed and microwave-treated paraffin sections were used for VDR immunohistochemistry employing a biotinylated monoclonal rat antibody and streptavidin peroxidase technique. The results showed that nuclei and cytoplasm of enterocytes stained positively for VDRs. Strongest immunoreactions were observed in intermediate and basal glandular cells. No significant differences were observed between the different groups. Vitamin D receptors immunoreactivities were prominent in duodenal mucosa, lower in jejunum and in colon, decreased further in ileum and were lowest in caecum. Decreases in number of positively marked cells and staining intensities resulted in reduced immunoreactions. The results of this study indicate that VDR are highly expressed at the site of maximal intestinal calcium absorption. No significant influence of age and breed was observed. The animals used were not in a negative Ca balance. The cows were all in the stage of late or mid lactation. During these periods, the Ca requirements are low and the diets are high in Ca concentration; and the animals are adapted to these circumstances. Passive absorption in adult animals seems to dominate when Ca intake is adequate or high. The active absorption may play a considerably more significant role during the peripartal period, when Ca homeostatic mechanisms are challenged because of tremendous Ca demand at the initiation of lactation. 相似文献
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Liesegang A Hatt JM Wanner M 《Journal of animal physiology and animal nutrition》2007,91(11-12):459-464
Calcium and phosphorus are very important minerals in reptile nutrition, but many diets are still not balanced. To achieve optimal growth, including a healthy skeleton and a strong shell, a well-balanced supply with these minerals is prerequisite. The purpose of this study was to evaluate the apparent digestibility in Hermann's tortoises of diets with different calcium levels with special emphasis on the digestibility of minerals. Eight adult Hermann's tortoises of the veterinary faculty in Zurich were used. The animals were housed indoors at a mean temperature between 23 degrees C and 26 degrees C. The animals were fed a diet, which consisted of vegetables, herbs and different supplementation of calcium carbonate. Daily faecal samples of all tortoises were collected from day 8 to day 12. A proximate analysis was performed and the HCl-insoluble ash was used as an indigestible natural indicator (marker) for the determination of the apparent digestibility of minerals. The calcium content of the mixed feedstuffs of diet I was 0.64% on a dry matter basis, and the Ca:P ratio in the food was 3:1. In diet II the Ca content was 1.29% on a dry matter basis, and the Ca:P ratio in the food was 6:1. The digestibility of Ca in diet I was 57%. The other examined minerals, Mg and P, had a digestibility of 46% and 58% respectively. In diet II the digestibility of Ca was 79%, of Mg 52% and of P 52%. The results of this study indicated, that higher Ca concentrations in the diet led to an increased apparent digestibility of Ca and Mg. 相似文献
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Létourneau-Montminy MP Narcy A Lescoat P Magnin M Bernier JF Sauvant D Jondreville C Pomar C 《Journal of animal science》2011,89(11):3596-3611
Environmental effects of excess P from manure and the soaring price of phosphates are major issues in pig production. To optimize P utilization, it is crucial to improve our capacity to predict the amount of P absorbed, while taking into account the main factors of variation. Mathematical modeling can represent the complexity of the processes and interactions in determining the digestive utilization of P in growing pigs. This paper describes and evaluates a model developed to simulate the fate of the dietary forms of P in the digestive tract of growing pigs, with particular emphasis on the effect of dietary Ca and exogenous phytase on P digestive utilization. The model consists of 3 compartments associated with specific anatomical sections: stomach, proximal small intestine, and distal small intestine. The main metabolic processes occurring in these sections are, respectively, P solubilization/insolubilization and phytate P hydrolysis, and P absorption and P insolubilization. Model parameters governing these flows were derived from in vitro and in vivo literature data. The sensitivity analysis revealed that the model was stable within a large range of model parameter values (±1.5 SD). The model was able to predict the efficacy of Aspergillus niger microbial phytase in accordance with literature values, as well as the decreased efficacy of plant phytase compared with microbial phytase. The prediction capabilities of the model were assessed by comparing actual and simulated P and Ca apparent total-tract digestibility (ATTD) based on published pig data not used for model development. Prediction of P digestibility across 66 experiments and 281 observations was adequate [P ATTD observed = 0.24 (SE, 0.943) + 0.98 (SE, 0.0196) × P ATTD predicted; R(2), 0.90; disturbance error (ED), 96.5%], whereas prediction of Ca digestibility across 47 experiments and 193 observations was less accurate (Ca ATTD observed = 11.1 + 0.75 × Ca ATTD predicted; R(2), 0.78; ED, 20.4%). A lack of agreement between experimental and simulated Ca digestibility was found. This model is, therefore, useful in evaluating P digestibility for different feedstuffs and feeding strategies. It can also be used to provide insight for improving dietary P utilization, especially from plant sources, by quantifying the effect of the mean sources of variation affecting P utilization. 相似文献
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A comparative meta‐analysis on the relationship of faecal calcium and phosphorus excretion in mammals 
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下载免费PDF全文 L. F. Böswald B. Dobenecker M. Clauss E. Kienzle 《Journal of animal physiology and animal nutrition》2018,102(2):370-379
To investigate the relationship between faecal calcium (Ca) and phosphorus (P) excretion in different mammalian species, a meta‐analysis on digestibility data derived from the literature was conducted. Seventy‐three studies on carnivores, omnivores, large and small hindgut fermenters, ruminants and hippos (a total of 21 mammalian species, precondition for inclusion dietary Ca/P ratio 1.5/1 – 3.0/1) were analysed for Ca and P digestibility. Dietary Ca/P ratios were lower than faecal Ca/P ratios in carnivores, omnivores, ruminants and hippos. In hindgut fermenters, dietary Ca/P ratios were higher than faecal Ca/P ratios, indicating higher intestinal Ca absorption in these species. In all species investigated, there was a significant positive relationship between Ca intake and faecal Ca excretion and between P intake and faecal P excretion. In the biologically relevant range, these equations predicted lower faecal Ca losses in hindgut fermenters than ruminants, for faecal P vice versa. In all species, faecal Ca and P excretion correlated significantly. In carnivores, this highly linear correlation was exceptionally strong (R² = .92). Yet, the linearity of the correlation was questionable in omnivores and ruminants. Possibly, the strong linear correlation of faecal Ca and P excretion in carnivores is due to the formation of insoluble Ca/P complexes in their relatively short and simple gastrointestinal tract. Another hypothesis is that in carnivores, Ca homeostasis relies on modifying bone turnover to a higher degree than on changes in intestinal Ca absorption. For the formation of bone matrix, a constant ratio of Ca and P absorption is of advantage. 相似文献
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Plant breeders developing cultivars to minimize the hazards of grass tetany are concentrating largely on increasing herbage Mg concentrations in cool-season (C3) grasses. Significant genetic variation has been found for Mg, Ca and K concentrations within C3 grass species studied to date. For most C3 forage grass species, heritability estimates are highest for Mg, slightly lower for Ca and lowest for K concentrations. The largest genotype x environmental interactions are found for K values, whereas small environmental effects have been observed for Mg and Ca values. No C3 forage grass cultivar has been developed to date that would eliminate hypomagnesemia. Grass breeders need to develop more experimental C3 plant populations that have high Mg and Ca concentrations. These experimental synthetics with genetically altered mineral concentrations need to be fed to ruminants susceptible to grass tetany to determine whether grass tetany can be eliminated or reduced. Limited feeding trials using ruminants show that improved animal performance can be expected when feeding forage grasses bred for higher Mg concentrations. 相似文献
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中型褐壳产蛋鸡饲粮钙适宜水平的研究 总被引：5，自引：0，他引：5
用 2 0周龄的商品代北京红鸡 1 5 0只 ,按完全随机设计以体重随机分为 5个处理组 ,分别喂以含钙水平为 2 .5 %、3.0 %、3.5 %、4.0 %和 4.5 %及非植酸磷水平均为 0 .2 5 %的玉米 豆粕型饲粮 2 0周 ,研究中型褐壳产蛋鸡在 2 0～ 40周龄产蛋阶段的饲粮钙适宜水平。饲粮钙水平对产蛋率、蛋重、产蛋量、耗料量、饲料效率、蛋形指数、哈夫单位、蛋壳百分率和血浆钙含量无明显影响 (P >0 .1 0 ) ,而显著影响了蛋壳厚度、蛋壳强度、蛋壳重、骨灰及蛋壳钙含量 (P <0 .0 5 )。随着饲粮钙水平的增加 ,蛋壳厚度、蛋壳强度和蛋壳重均呈曲线型增加 ,当饲粮钙水平升至 4.0 %时均增至最大。本次研究结果表明 ,蛋壳厚度、蛋壳强度和蛋壳重是评价中型褐壳产蛋鸡饲粮钙营养需要量的敏感指标 ;北京红中型褐壳产蛋鸡在 2 0～ 40周龄产蛋阶段的玉米 -豆粕型饲粮中钙水平以 4.0 %(实测值为 3.94%,每日钙进食量为 4.1 8g)为宜 ,比美国现行NRC( 1 994)对中型褐壳产蛋鸡饲粮钙建议需要量 ( 3.2 7%钙 ,每日钙进食量为 3.60g)的高 相似文献
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The involvement of Ca++ ions as secretory mediators in pig jejunal epithelia has been investigated with an in vitro system. Omission of Ca++ from the Ringer-HCO3 bathing media on both sides of the tissue had minor effects on the basal electrical activity of pig jejunal mucosa. There were only slight decreases in transepithelial potential difference and increases in conductance with Ca++ free media. Low EGTA concentrations which reversibly blocked potential difference responses to secretory agents also had minimal effects on basal electrical activity. The in vitro secretory responses to A23187, to theophylline, and to Escherichia coli heat-stable enterotoxin were all eliminated by Ca++ depletion and restored by replacing normal Ca++ concentrations in the bathing media. Dantrolene prevented the secretory response but not the potential difference increases caused by heat-stable enterotoxin and A23187, suggesting that intracellular Ca++ stores may be reservoirs of secretory signal agent. Verapamil only blocked the secretory response to heat-stable enterotoxin. Chlorpromazine had negligible effects on basal conditions, but totally blocked both the secretory response and the Ca++-dependent effects of A23187 and heat-stable enterotoxin on potential difference. The response to theophylline was only partially inhibited by chlorpromazine, implying some involvement of both cAMP and Ca++ as secretory signals for theophylline. Cytoplasmic Ca++ concentrations appear to be at least as important as cyclic nucleotides in regulating the secretory effects of pig jejunum. 相似文献
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The influence of Ca2+ ions on the cytotoxic activity of Pasteurella haemolytica leukotoxin was investigated. The divalent cation influenced the cytotoxic effect of the leukotoxin for sensitive BL-3 target cells, but its absence did not eliminate cytotoxicity. In short-term 1-h assays using neutral red uptake as a measure of cell viability, depletion of Ca2+ either by exhaustive dialysis or by addition of the Ca2+ chelators EDTA and EGTA eliminated the cytolytic effect of low doses of the toxin. Addition of Ca2+ to target cell cultures depleted of the divalent cation restored the cytolytic effect of the leukotoxin. Prolonged exposure of the BL-3 cells to the toxin abrogated the protective effect of EDTA and EGTA. Cell death measured by uptake of neutral red, exclusion of trypan blue and 51Cr release indicated that protection observed in the absence of free Ca2+ was temporary. Toxin-induced cytolysis equivalent to that observed in the presence of Ca2+ occurred following the initial 2-h exposure. In addition, verapamil, a Ca2+ channel blocker, prevented cell death during 1-h cytotoxicity assays. The protection afforded by verapamil was dose-dependent and was influenced by the concentration of Ca2+ in the buffer medium. The results suggest that Ca2+ positively influences the rapid initial phase of cell death resulting from exposure to the toxin, but is not required for the entirety of the cytolytic process. 相似文献
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Schröder B Breves G 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2006,7(1-2):31-41
Adequate blood calcium (Ca) concentrations are a prerequisite to maintain several physiological functions of mammals such as pig and ruminants. Thus, blood Ca levels have to be regulated within very close limits. This is basically ensured through the coordinated effects of the calcitropic hormones parathyroid hormone (PTH) and calcitriol (1,25-dihydroxyvitamin D3). If plasma Ca decreases, one main effect of subsequently secreted PTH is the stimulation of renal reabsorption of Ca from the glomerular filtrate to reduce urinary Ca loss. Another important action of PTH is the induction of the renal enzyme 1 alpha-hydroxylase, which is responsible for the production of calcitriol. In most monogastric species, so far investigated, one of the most important effects of calcitriol is to stimulate active absorption of Ca from the gastrointestinal tract, particularly the upper small intestines, via a vitamin D-receptor-mediated genomic action. Whether this concept can be transferred without any constrictions to ruminants is still under discussion. Marked interspecies differences have to be recognized with respect to ruminant or non-ruminant animals, particularly with respect to individual segments along the gastrointestinal axis and with respect to vitamin D sensitivity of Ca transport mechanisms. This review will elucidate some of the current concepts related to the mechanisms and sites of Ca absorption in pigs and ruminants with special emphasis on dairy cows where Ca homeostasis is occasionally compromised at the time of parturition. 相似文献
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van Doorn DA van der Spek ME Everts H Wouterse H Beynen AC 《Journal of animal physiology and animal nutrition》2004,88(11-12):412-418
Literature data show conflicting results on the effect of feeding high calcium (Ca) levels on phosphorus (P) digestibility in ponies. None of the studies reported involved a dose response as to the effect of Ca intake on apparent P digestibility while keeping P intake constant. Thus, the influence of high dietary Ca level on apparent P digestibility was studied in balance trials by feeding six mature ponies three different Ca levels against a constant P intake. The ponies received 148, 316 and 535 mg Ca/kg BW/day with the low, intermediate and high Ca diet. Phosphorus intake was approximately 125 mg P/kg BW and magnesium (Mg) intake was approximately 35 mg Mg/kg BW/day. The intermediate and high Ca level decreased apparent digestibility, renal excretion and retention of P when compared with the low Ca level. However, apparent digestibility and renal excretion of P were not different between the intermediate and high Ca level. The high Ca level resulted in a retention of 66 mg Ca/kg BW/day. The percentage apparent digestibility of Ca was lower for the intermediate and high Ca level compared with the low Ca level. Magnesium digestibility was not affected by high dietary Ca level. In practice, high absolute amounts of Ca should be prevented especially when low amounts of P are fed; P digestibility will be depressed and a negative P balance may occur. 相似文献