尿素-麻饼型日粮条件下绵羊瘤胃内烟酸产生、消失及流通规律研究

选用3只体重为35-43 kg安装永久性瘤胃痿管、十二指肠近端瘘管的内蒙古半细毛羯羊,在饲喂尿素-麻饼型日粮条件下,通过非同位素Co标记烟酸的启动-连续灌注方法,测定绵羊瘤胃烟酸的基本产生、消失、外流速率及十二指肠的流通速率。试验结果表明:饲喂尿素-麻饼型日粮的绵羊瘤胃烟酸的基本产生速率为2．92 mg/h。通过灌注的方法提高烟酸产量后,烟酸在瘤胃内的产生速率为5．62 mg/h;消失速率为2．65 mg/h;瘤胃内烟酸的外流速率为2．97 mg/h;同时得出烟酸在十二指肠的流通速率为1．74 mg/h。     

麻饼型日粮条件下绵羊瘤胃内烟酸的产生、消失及流通规律

选用3只体重为35～43kg安装永久性瘤胃瘘管、十二指肠近端瘘管的内蒙古半细毛羯羊,在饲喂麻饼型日粮条件下,通过非同位素标记烟酸的启动——连续灌注方法,测定绵羊瘤胃烟酸的基本产生速率。并通过连续灌注的方法,提高烟酸在瘤胃内的产生速率后,再测定烟酸在瘤胃内的消失速率、瘤胃内烟酸的外流速率及十二指肠的流通速率。结果表明,饲喂麻饼型日粮的绵羊瘤胃烟酸的基本产生速率为2.69mg/h。通过灌注的方法提高烟酸产量后,烟酸在瘤胃内的产生速率为5.09mg/h;消失速率为1.77mg/h;瘤胃内烟酸的流通速率为3.32mg/h;同时测得烟酸在十二指肠的流通速率为1.80mg/h。     

豆粕型日粮条件下绵羊瘤胃内烟酸的产生、消失及流通规律

选用3只体重为35-43kg、安装永久性瘤胃瘘管、十二指肠近端瘘管的内蒙古半细毛羯羊，在饲喂豆粕型日粮条件下，通过非同位素标记烟酸的启动-连续灌注方法，测定绵羊瘤胃烟酸的基本产生、消失、外流速率及十二指肠的流通速率。试验结果表明，饲喂豆粕型日粮的绵羊瘤胃烟酸的基本产生速率为2．50mg／h。通过灌注的方法提高烟酸产量后，烟酸在瘤胃内的产生速率为5．06mg／h；消失速率则为1．90mg／h；瘤胃内烟酸的外流速率为3．16mg／h；同时得出烟酸在十二指肠的流通速率为1．73mg／h。     

尿素-麻饼型日粮中添加烟酸对绵羊瘤胃发酵的影响

烟酸是畜禽必需的维生素之一，是动物体内2个重要脱氢酶的辅酶NAD^ 和NADP^ 的重要成分，在动物机体代谢中起着至关重要的作用。麻饼作为反刍动物常用的一种饲料原料，可以提供瘤胃蛋白来源,而尿素又是一种反刍动物最常用的非蛋白含氮物质．研究它们配合后的日粮对反刍动物及其瘤胃发酵的影响是非常有必要的。试验利用体外试验法，以内蒙古半细毛羯羊为试验动物，在以尿素一麻饼型日粮为培养底物的培养液中补加不同剂量的烟酸后,测定其若干瘤胃指标。用以确定烟酸适宜添加剂量范围，为配制舍饲育肥绵羊预混料提供理论依据。     

利用体外培养研究麻饼型日粮添加烟酸对绵羊瘤胃发酵的影响

以麻饼——玉米型日粮为培养底物及瘤胃液供体动物日粮,试验用瘤胃液来自3只安装永久性瘤胃瘘管的绵羊,体外试验按不同烟酸添加剂量分为13个试验组(0,50,150,250,350,400,450,500,600,700,800,900,1000mg／kg),每个试验组4个重复。在培养24h后,测定培养液中NH3-N、瘤胃细菌N产量、原虫数量、总VFA产量及乙酸、丙酸、丁酸产量和乙酸／丙酸值,用以确定在该氮源日粮条件下,添加烟酸对瘤胃发酵的影响,并对烟酸最适添加范围进行了研究。结果表明,在麻饼型日粮来源培养底物中,最适烟酸添加范围为450～500mg／kg。     

麻饼型日粮中添加烟酸对绵羊瘤胃发酵底物降解动力学研究

本试验旨在研究麻饼型日粮中添加一定量烟酸(450mg/kg)后,在体外培养过程中,发酵底物在不同培养时间内培养液中NH3-N浓度、瘤胃细菌N产量、原虫数量、总VFA量及乙酸、丙酸、丁酸产量和乙酸/丙酸值的降解动力学特征.体外试验瘤胃液来自3只安装永久性瘤胃瘘管的绵羊,饲喂添加烟酸的麻饼型基础日粮.试验结果表明,添加烟酸可提高培养液NH3-N利用率;培养液中添加烟酸后瘤胃细菌N产量在整个培养过程中高于未添加组;培养液中原虫教在培养4 h时达最高值,且此时添加组原虫产量显著(P＜0.05)高于未添加组;总VFA量及乙酸、丙酸、丁酸的产量随培养时间变化而呈增加趋势;但丁酸量和乙酸/丙酸值与对照组相比差异不显著(P＞0.05).     

体外培养法测定不同氮源日粮中烟酸的动态降解规律

本试验按培养底物的氮源不同分为3个系列,分别为豆粕、麻饼和尿素—麻饼系列,每个系列又分为试验组(烟酸添加量为450mg/kg)和对照组,再按不同培养时间分为11个采样点(0h、0.5h、1h、2h、4h、6h、8h、12h、16h、20h、24h),每个采样点有3个重复。在每一个时间点采样后测定其烟酸量,研究烟酸的动态降解规律。结果表明,在体外培养过程中,3种氮源日粮中添加烟酸后,在培养0～8h,烟酸的合成量均大于降解量。在培养12～24h,合成量均小于降解量。在不添加烟酸情况下,当培养0～8h时,烟酸的合成量均大于降解量。当培养12～24h,合成量均小于降解量。     

肉鸭对杂粕型日粮烟酸的需要

烟酸又名尼克酸、维生素PP或抗癫皮病维生素,为白色、无味的针状结晶,是具有生物学活性的嘧啶类衍生物,理化性质稳定,不易被酸、碱和热破坏。烟酸作为辅酶的重要前提物质,参与体内多支     

间接法评定绵羊瘤胃丙酸产生、吸收和流通规律研究

利用非同位素标记丙酸的启动－连续灌注的方法，采用非标记酸灌注条件下计算丙酸基本产生量的原理，研究了绵羊瘤胃碳水化合物产生丙酸的基本速率和通过灌注提高丙酸产生速率后，丙酸在瘤胃的消失率，离开瘤胃的流通速率；丙酸在瓣胃和真胃及小肠的吸收及其它有关液相指标的影响。研究表明：当试验绵羊饲喂粗精比为54：46的日粮并满足维持饲养水平时，测得的丙酸基本产生速率为22．4mmol/h，瘤胃丙酸库容量为51.94mmol,仅占丙酸日产量的9．6％，还确定了瘤胃灌注丙酸后获得稳态的条件是：瘤胃液相pH的变异系数CV＜0．5％，丙酸浓度的变异系数＜6％，标记物Co浓度的变异系数＜5％；丙酸在瘤胃的吸收速率与其在瘤胃的产生速率成正比（P＜0．01），当丙酸的产生速率从37．14提高至145.07mmol/h时，瘤胃吸收的丙酸占丙酸产生量的2／3以上，而随液体离开瘤胃的丙酸不足丙酸产生量的1／3。进一步的研究证实，离开瘤胃的丙酸在瓣胃和真胃有96％以上被吸收，有3％－4％进入十二指肠；同时还获得了一系列通过瘤胃丙酸产生速率（PROD丙酸，mmol/h）预测其它液相特性指标的关系方程。     

日粮精粗比对活体外瘤胃发酵和烟酸、烟酰胺合成的影响

本试验旨在研究日粮精粗比对活体外瘤胃发酵和烟酸、烟酰胺合成的影响。以4头装有永久性瘤胃瘘管的成年荷斯坦阉公牛作为瘤胃液供体,选用淀粉、微晶纤维素、酪蛋白3种成分配制成相同粗蛋白质水平(13.5%,DM)和不同精粗比(30:70、50:50、70:30,DM)的3种纯合日粮作为发酵底物。应用人工瘤胃体外产气量法进行培养发酵并测定产气量、挥发酸及发酵液中烟酸、烟酰胺含量的变化。结果表明,提高日粮精粗比可极显著降低发酵液pH、乙酸/丙酸摩尔比、乙酸摩尔比(L,P<0.01),显著降低氨态氮浓度(L,P<0.05),但却极显著增加72 h产气量、总挥发酸浓度、丙酸和丁酸摩尔比(L,P<0.01)。随日粮精粗比的提高,瘤胃发酵液中总烟酸(烟酸+烟酰胺)、烟酰胺浓度在24和48 h均呈线性增加(L,0.050.10)。由此得出,日粮精粗比可改变活体外瘤胃发酵模式和影响瘤胃微生物合成总烟酸和烟酰胺,且随日粮精粗比的上升,瘤胃合成总烟酸、烟酰胺的数量呈线性增加趋势。     

Effects of soybean meal supplementation on ruminal kinetics of feed particle size reduction and passage in dairy cows fed rice straw

Six ruminal-cannulated nonlactating Holstein Friesian cows (mean body weight:660 ± 42.9 kg) were used to investigate the effect of soybean meal (SBM) supplementation on voluntary rice straw (RS) intake, feed particle size reduction, and passage kinetics in the rumen. They were allocated to two dietary treatments: RS alone or RS supplemented with SBM. Voluntary dry matter intake of RS and total tract fiber digestibility was increased by SBM supplementation (p < 0.05). Supplementation with SBM decreased rumination time per dietary dry matter (DM) and neutral detergent fiber (NDFom) intake (p < 0.01). Particle size distribution in the rumen and total ruminal NDFom digesta weights were not affected by SBM supplementation. However, the disappearance rates of total digesta and large and small particles from the rumen were increased by SBM supplementation (p < 0.01). Moreover, SBM supplementation increased the rate of size reduction in ruminal particles (p < 0.05). In situ disappearance of DM and NDFom of RS in the rumen was greater in SBM-supplemented cows than in nonsupplemented cows (p < 0.05). This study clearly showed that increased ruminal RS particle size reduction, passage, and fermentation due to SBM supplementation accelerated the RS particle clearance from the rumen and resulted in increased voluntary RS intake of dairy cows.     

不同处理对大豆浓缩蛋白（SPC）粗蛋白含量及提取率的影响

分别用超声波处理不同粉碎粒度的高温脱脂豆粕,然后采用醇法浸提工艺提取其中的大豆浓缩蛋白（SPC）。结果显示：40目、60目及80目豆粕提取的大豆浓缩蛋白中粗蛋白含量分别为51．85％、55．50％和54．32％（P〈0．05）。提取率分别为97．65％、97．51％和95．80％（P〈0．05）;超声波处理之后提取的大豆浓缩蛋白中粗蛋白含量分别为55．44％、55．11％和58．77％（P〈0．05）,提取率分别为97．50％、96．78％和95．65％（P〈0．05）。不同的粉碎粒度对大豆浓缩蛋白中粗蛋白的含量及提取率有显著影响,粒度越小,粗蛋白含量越高,提取率越低;在相同的粉碎粒度下,超声波处理能提高大豆浓缩蛋白中粗蛋白的含量,但是对其提取率无显著影响。     

大豆油不同添加水平对瘤胃体外发酵和产气的影响

本试验通过体外培养,研究在精粗比为30:70(偏粗型)日粮类型条件下,不同大豆油添加水平对产气量、甲烷产量、pH值和纤维降解率的影响.结果表明:随着大豆油添加水平的提高,产气量和甲烷产量逐渐降低,且各添加组显著低于对照组;pH值随着培养时间的延长,各添加水平在不同培养时间点与对照组相比均上升,其中添加量为4%和6%与对照组相比差异显著(P<0.05),添加量为8%时,与对照组相比差异极显著(P<0.01);培养24 h后.纤维降解率的抑制潜力8%水平最大,与对照组相比差异极显著(P<0.01),其次是6%的添加水平.与对照组相比差异显著(P<0.05).而2%和4%添加水平对纤维降解率的抑制程度与对照组相比差异不显著(P>0.05).通过产气量、pH值和纤维降解率综合考察大豆油对瘤胃体外发酵和产气的影响,本试验得出大豆油的最适添加量为4%.     

The particulate passage rate,nutrient composition and fermentation characteristics across gastrointestinal tracts in lactating dairy cows fed three different forage source diets

This study was conducted to investigate the particulate passage rate, nutrient characteristics and fermentation parameters across the gastrointestinal tract (GIT) in lactating dairy cows fed cereal straws in comparison with alfalfa hay. Eighteen multiparous Holstein cows were randomly assigned to one of three experimental diets consisting of 55% concentrate, 15% corn silage and 30% different forage sources as follows (% of dry matter [DM]): (i) 23% alfalfa hay and 7% Chinese wild rye hay (AH); (ii) 30% corn stover (CS); and (iii) 30% rice straw (RS). The Cr‐mordanted corn silage‐neutral detergent fibre was used to estimate the passage flow at week 14. After 14‐week feeding, the animals were slaughtered to collect the gastrointestinal digesta. Dietary forage sources had little effect on the fractional passage rates in the rumen (range from 5.05 to 6.25%/hr) or hindgut (range from 4.49 to 5.24%/hr). Total volatile fatty acid (VFA) concentration in the caecum was highest, followed by the rumen, colon and rectum, and the lowest in the abomasum and duodenum, indicating that the large intestines, especially caecum, are the important positions for carbohydrate degradation. Greater proportion of propionate and butyrate and lower acetate were found in the AH compared to CS or RS in colon, but higher acetate in abomasum was found in the cows fed CS or RS compared to AH. In conclusion, cereal straw diets did not change the particulate passage rate in the rumen and hindgut which might be mainly due to the similar DM intake among these three diets. Different forage source diets significantly changed VFA proportion in the abomasum and colon, indicating the existence of different digestion or absorption rates in these tracts among the experimental diets.     

Seasonal changes in digestibility, passage rate and rumen fermentation of alfalfa hay in sika deer (Cervus nippon) under restricted feeding

To investigate seasonal variations in the digestive functions of sika deer, five female sika deer were provided with an amount of alfalfa hay cubes equivalent to voluntary food intake during winter. We measured the rate at which the food passed through the digestive tract, digestibility and rumen fermentation during the summer (August), autumn (November), winter (February) and spring (May). Total mean retention time in the digestive tract during summer and autumn was numerically longer than that in winter and spring, but the difference did not reach significance. Organic matter and fiber were less digestible in summer and autumn than in winter and spring (P < 0.05), whereas the digestibility of the dry matter tended to vary with the seasons (P < 0.1). Ruminal pH values seasonally changed (P < 0.01), and were the lowest in autumn. The concentration of ruminal ammonia‐nitrogen differed significantly among the seasons (P < 0.05), increasing in winter and decreasing during spring and summer. The numbers of protozoa changed significantly among the seasons (P < 0.05), being higher in autumn than in winter and spring, and intermediate in summer. The concentration of total volatile fatty acids was not seasonally affected, but the molar percentages of propionic acid and butyric acid significantly changed according to season (P < 0.05 and P < 0.01, respectively), and the ratio of acetic to propionic acid tended to change with the seasons (P < 0.1). The results of this study suggested that the digestive functions in sika deer, fed a commercial diet at a restricted level, differed notably among the seasons and these variations might partially be due to environmental effects.     

Comparison of digestibility, passage rate and rumen fermentation between sika deer (Cervus nippon) and cattle fed alfalfa hay cubes

Five female sika deer and three male Holstein cattle were offered alfalfa hay cubes at 2% (deer) and 2.5% (cattle) of bodyweight, respectively. The passage rate through the digestive tract, digestibility and rumen fermentation of the animals were determined. The rate of ruminal passage was higher and the total mean retention time in the digestive tract was shorter in deer than in cattle. In addition, the rate of post‐ruminal passage in deer was lower. The digestibilities of dry matter, organic matter, crude protein and fiber in deer were significantly lower than in cattle (P < 0.05). The concentration of total volatile fatty acids in the rumen was significantly higher in deer than in cattle. The molar percentage of acetic acid was lower and that of valeric acid was higher in deer (P < 0.05). The number of protozoa was somewhat higher in deer. These results suggested that the lower digestibility in deer might be a result of the shorter retention time in the digestive tract.     

Effects of dietary protein and carbohydrate source on rumen fermentation and nutrient flow in sheep

The effects of decreasing levels of rumen degradable protein (RDP) and nonstructural carbohydrate (NSC) (Diet 1: 74% RDP and 38% NSC; Diet 2: 57% RDP and 32% NSC; Diet 3: 48% RDP and 23% NSC) were studied in cannulated sheep. Total volatile fatty acid (VFA) content rose in response to increasing NSC content. The molar ratio of acetate to propionate was the narrowest for Diet 1. Ruminal concentrations of ammonia and urea increased in response to the rising level of RDP. Flow of organic matter (OM) to the duodenum was increased for Diet 3, which resulted in the lowest apparent and true ruminal digestion of OM. Duodenal flow of total nitrogen (N) increased as RDP content decreased. The highest quantity of undegraded feed protein in duodenal digesta was measured in sheep fed Diet 3. Microbial N flow and microbial efficiency were unaffected by the diets. These results indicate that an NSC level lower than 25% and an RDP content lower than 50% did not exert any negative effect on microbial N production. This phenomenon supports the theory that if the level of RDP is lowered with a concomitant decrease in NSC, uncoupled fermentation cannot be observed.     

低豆粕日粮对产蛋鸡生产性能及蛋品质的影响

试验选用1 600只生产性能相同、体况良好的33周龄罗曼蛋种鸡,随机分为4组,在总蛋白质含量相同和满足必需氨基酸需要量的情况下,用价格较低的蛋白饲料取代蛋鸡日粮中豆粕,研究氨基酸平衡的低豆粕日粮对蛋种鸡生产性能和蛋品质的影响。结果表明:氨基酸平衡的低豆粕日粮对蛋鸡产蛋率、种蛋合格率、健雏率、蛋形指数、蛋比重、蛋壳厚度、哈氏单位等指标无显著影响(P>0.05),但当日粮中的豆粕含量降低8～15个百分点时,蛋种鸡的日平均蛋重、日采食量、受精率、孵化率等显著低于正常豆粕日粮(P<0.05),而考虑综合因素日粮中的豆粕含量降低8个百分点的第1组,与正常豆粕日粮相比,差异不显著(P>0.05),而且能降低饲料成本,可以提高蛋鸡养殖效益,具有实际意义。