Sugar beet mash silage as a component of a total-mixed-ration for dairy cows--effects on parameters of digestion and animal performance.

Sugar beet mash silage (BMS) was offered in amounts up to 35% of DM to dairy cows as a component of a total-mixed-ration (TMR). Barley and molasses in the control ration were replaced by BMS half in ration BMS 1/2 and in total in ration BMS 1/1 on the basis of the calculated contents of net energy for lactation. Two trials were carried out. In trial I each ration was tested on parameters of rumen fermentation and digestibility of crude nutrients using 4 Holstein cows with rumen fistula. Chewing activity was tested on 2 Holstein cows for each ration. With the BMS rations the ruminal NH3 concentration was lower and the drop in pH was less than in the control ration. The pattern of volatile fatty acids in the rumen fluid from the BMS groups tended towards more propionic and butyric acid. The feeding of BMS showed no negative impact on chewing and rumination. Energy digestibility raised significantly from 59.8% in the control ration to 72.6% in the BMS 1/1 ration. In trial II the same rations were fed in a change-overdesign to a herd of 24 Holstein cows to test feed intake and animal performance. The results showed no significant effects of BMS rations on DM intake and milk production. The results of both trials indicate that even high amounts of cereals can be replaced by BMS without negative effects on rumen fermentation, milk yield and milk composition with slight drop in fat content. For a better handling of BMS, it is of advantage to include it in a TMR.     

The effect of sugar beets in the ration on metabolism in the forestomach of 11 to 20-week-old calves

The influence of the replacement of cereals by sugar beet in the rations was tested with 6 calves supplied with re-entrant duodenal or ruminal cannulae in 4 measuring periods between their 11th and 17th weeks of life. The control ration (A) consisted of 60% mixed feed, 20% hay and 20% wilted silage, the test ration (B) consisted of 30% mixed feed, 33% sugar beet, 20% hay and 17% wilted silage. A contained 15% crude protein, 32% starch and 2% sugar, B in the same sequence 14, 12 and 24% (amounts in % of DM). The following results were achieved: The functional development of the rumen is largely completed three weeks after weaning. There were no qualitative changes between the 11th and 17th weeks of life. The fermentation of organic matter in the rumen (50...52%) and bacterial protein yield (2.4...2.6 g N per 100 g digestible organic matter) corresponded to that of adult ruminants. The partial replacement of cereals by sugar beet resulted in a significant increase of the molar butyric acid quota to 20.8% (B) in comparison to 13% (A) with the same level of total volatile fatty acids in the rumen, the decrease of the quota of acetic acid to 61.4% (B) in contrast to 73.5% (A) and the reduction of the ruminal NH3 concentration after feeding. The feeding of sugar beets had a positive influence on the passage of starch in the duodenum. The DM-degradation of straw in polyamide bags was also positively influenced. 62.6% (A) and 73.9% (B) of the feed N were degraded in the forestomachs. Per kg DM intake 29.8 g (A) and 28.0 g (B) non-ammonia-N (NAN) were detected at the duodenum. 54% (A) and 64% (B) of NAN consisted of bacteria N. In contrast to adult ruminants at nutrition level 1 (maintenance) a considerable net influx of endogenous N into the rumen was to be observed at a crude protein concentration in the feed of 14 to 15% (in the DM) in both groups. Accordingly, the minimum protein content of the ration (in the DM) should be above 15% in the rearing range studied.     

Effect of different types of rations on various characteristics of ruminal and intermediary metabolism in sheep. 1. Formation of volatile fatty acids]

Studies on Ruminal Physiology were made with 15 growing female Merino sheep to investigate the influence of different types of rations on the fermentation of volatile fatty acids. The rations were constructed of green feed, straw and concentrates (type 1) or chemically treated straw pellets + concentrates (type 2). One ration (type 3) consisted of concentrates only. With regard to the total concentration of acids ration 3 was significantly superior to the 2 other types of rations. Moreover, ration 3 produced a specific fermentation pattern of the volatile fatty acids. This was characterized by a significant reduction in the molar proportion of acetate compared with ration 1 and 2 and a significant increase in the level of propionic and valeric acid relative to ration 1. Differences in the fermentation pattern between rations 1 and 2 were mainly limited to differences in the absolute and molar proportions of propionate where the straw pellet rations in each case produced the significant higher values. The acetate to propionate ratio was narrowed in the order of ration 1-3 (4.1 :1, 3.1:1, 2.6-2.9 :1). Statistically wellestablished negative correlations were found to exist between the concentrations of volatile fatty acids and the pH values which were established simultaneously.     

Studies on the various sugar-urea and sugar-starch-urea relationships with reference to the fermentation in the rumen and the digestibility of nutrients in fattening cattle]

Recommendations are given saying that sugar-to-crude fibre rations of not more than 1.7:1 and sugar-to-urea ratios of 12:1 should be used in the fattening of cattle fed urea-supplemented rations of roughages in which 40% to 50% of the crude protein content of the ration had been replaced by urea. The amount of sugar per kg live-weight should not exceed 4 g. Higher quantities reduce the digestibility of crude fibre and, additionally, decrease the NH3 level and the pH in the rumen. At the same time the amount of volatile fatty acids is increased while the content of ruminal acetic acid decreases. Variations in the sugar-to-starch ratio had no statistically significant influence on the nitrogen balance whereas it was found that increasing quantities of sugar significantly decreased the digestibility of crude fibre. The proportional content of sugar in the readily metabolisable carbohydrates contained in the ration should not exceed 20% to 50%.     

The effect of citronellylseneciate on the utilization of feed in sheep

The influence of citronellylseneciate on the digestibility of nutrients and energy, as well as on the level of some rumen and blood metabolites, was studied in feed rations for rams. Citronellylseneciate was not found to have a significant influence on the digestibility of nutrients and energy and nitrogen balance in feed ration. Neither did citronellylseneciate influence the production of total volatile fatty acids and the molar percent of acetic, propionic and n-butyric acids. The addition of citronellylseneciate to feed ration resulted in a decrease in the pH value in rumen and in a non-significant increase in ammonia in rumen and urea in blood. The hematological profile showed increased levels of phosphorus and glutamate-oxalate transferase.     

The effect of straw in ground and pelleted form on the rumen fermentation and protozoa]

Cows possessing a large ruminal fistula were fed straw meal and pelleted wheat straw to investigate its effect on ruminal fermentation (concentration of NH3 and volatile fatty acids (FFS), pH, molar proportions of FFS, rates of FFS production) and on the protozoa population. The straw-concentrate mixture used in the present trial contained 40% of straw. The feeding of pelleted straw produced a significant rise in FFS concentrations (from 8.8. to 12.3 mMole/100 ml) and a corresponding decline of pH (from 6.7 to 6.1). With high molar proportions of acetate (72 mole%) the influence of the straw diet on molar FFS proportions was low. The NH3 peak observed 1 hr after feeding was higher with the pelleted straw than with the straw meal. The feeding of finely gound straw produced a higher level of FFS production (by 10%) than that of straw pellets. (3.88 and 4.29 mMole per gm DM). The number of protozoa (per ml of ruminal fluid) was 335,000 (straw meal) and 121,833 (pellets). The number of large infusorial cells (Isotricha, Diplodinium, Ophryoscolex) decreased correspondingly from 70,000 (straw meal) to 18,870 per ml (pellets). These results suggest that the feeding of pelleted straw-concentrate mixtures to cows as sole feed will not bring about optimum conditions for ruminal fermentation (FFS formation, protein synthesis) and for the layering of ruminal contents.     

Effect of feeding pelleted feed on the level of volatile fatty acids in the digestive tract of sheep]

In an experiment with wethers we investigated the effect of complete pelleted feed ration on the concentration of volatile fatty acids in the rumen and intestinal tract. The animals consumed daily 1,300 g of dry matter of a diet which contained 41.81% of meadow hay, 25.28% of barley, 15.37% of sawdust, 14.98% of molasses, 1.32% of urea and 1.24% of a vitamin-mineral supplement for a period of six months. The pelleted diet increased the total amount of volatile fatty acids, the content of propionic acid and especially the content of butyric acid. There appeared a decrease in the ratio of acetate: propionate. On the basis of the greater energy efficiency of the volatile fatty acid production the animals fed pelleted feed showed a better energy balance. A higher VFA concentration was determined also in the large intestine and the cecum, which proves the importance of fermentation porcesses in these organs.     

The effect of the early feeding of solid and bulk foods on the dynamic development of the digestive processes in calves ina large-scale breeding facility

Digestive activities were studied in test calves (n = 12) in relation to age and feed intake. The calves were isolated after birth from adult cows. Since the 14th day of age, milk replacers were fed with concentrate feed mixture TG and alfalfa hay, i.e. the calves were in the period of plant feeding. The investigation lasted from the end of milk feeding (50th day) to the age of six months. Overall health condition was studied clinically. The characteristics of digestive activities studied in rumen fluid at weekly--monthly intervals were pH, ammonia content, total content of volatile fatty acids, content of particular volatile fatty acids, incidence and number of infusoria. At the age of 50 days, actual pH of rumen fluid was on the average 6.07 and it ranged from 5.84 to 6.76 in the next period. Ammonia content was the highest at the age of 50 days (21.49 mmol/l rumen fluid), then it dropped to 9.83 mmol/l rumen fluid at the age of 180 days. The average total concentration of volatile fatty acids (C2-C5) made 117.00 mmol/l during the first examination, it increased to 132.98 mmol/l at the age of 84 days, and it dropped to 94.16 mmol/l rumen fluid at the age of six months. A similar tendency was found in the volatile fatty acids. The infusoria were found out only at the age of 120 days--their numbers were 155 000 per ml; at the age of 180 days their numbers rose to 368 000 per ml rumen fluid. No disorders of health condition were recorded during the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)     

茴香秸秆和茴香秕壳对绵羊营养价值的评定

选择6只体重28 kg左右,安装永久瘤胃瘘管甘肃高山细毛羯羊, 采用3×3无重复拉丁方试验设计,通过消化代谢试验,对茴香秸秆和茴香秕壳对绵羊的营养价值进行了评定。结果表明,绵羊对茴香秸秆和茴香秕壳的干物质消化率、氮消化率、氮存留率、有机物消化率、中性洗涤纤维消化率、酸性洗涤纤维消化率、钙消化率、磷消化率和消化能分别为62.11%和61.63%,63.83%和65.63%,50.58%和47.72%,62.63%和62.50%,54.95%和53.02%,52.18%和49.50%,23.19%和20.35%,31.98%和35.03%,以及9.86和9.51 MJ/kg。绵羊对茴香秸秆和茴香秕壳的消化率较高。饲粮中添加茴香秸秆对绵羊瘤胃液pH、乙酸摩尔比、丙酸摩尔比、丁酸摩尔比、乙酸/丙酸以及瘤胃液中尿素氮和蛋白氮浓度均产生了显著的影响(P<0.05),对其他酸摩尔比、瘤胃液总挥发性脂肪酸(TVFA)、总氮和氨氮浓度无显著影响(P>0.05);饲粮中添加茴香秕壳对绵羊瘤胃液乙酸、丁酸和其他酸摩尔比产生了显著的影响(P<0.05),对pH、丙酸摩尔比、乙酸/丙酸、瘤胃液TVFA和氮浓度无显著影响(P>0.05)。     

The effect of Rumensin on the metabolic profile of rumen fluid in feedlot cattle

The effects were studied of sodium monensinate dosed 125 mg on the metabolic profile of rumen fluid. The experiment was conducted under current farming conditions in a pavilion cattle fattening house. The experiment, which lasted 367 days, comprised 985 bulls of the Bohemian Spotted breed. The feed ration was based on silage with an additive of dried poultry litter and concentrates. The additive was administered in concentrate mixture, 125 mg per head/day. After the start of the experiment want of appetite to sodium monensinate was observed. The animals took approximately four weeks to adapt completely to the additive. The following characteristics were investigated to study the metabolic profile of rumen fluid: actual acidity, total titration acidity, ammonia, total nitrogen, lactic acid, total volatile fatty acids, per cent acetic acid, per cent propionic acid, molar ratio acetic acid: propionic acid, per cent iso- and n-butyric acid, absolute number of infusoria and energy net yield of volatile fatty acids. Increased levels of the clinico-biochemical parameters of the metabolic profile of rumen fluid were found in lactic acid, propionic acid and energy net yield of volatile fatty acids. The per cent of propionic acid increased at some samplings by up to 116%. A drop was recorded in total nitrogen, per cent acetic acid, per cent butyric acid, molar ratio C2 : C3 and total number of infusoria. The decrease in the per cent of acetic acid ranged around 16% and the drop in butyric acid level amounted at some samplings up to 78%. No response to the additive was observed in the other characteristics of the metabolic profile of rumen fluid.     

Dependence of rumen fatty acid production on the composition of rations

In three experiments with two Black-and-White dairy cows the influence of soybean oil and coconut fat as well as that of rations rich in roughage and concentrated feed on the production of fatty acids were determined with the isotope dilution method. A change in the method of sampling from the rumen in the course of the investigations resulted in distinctly different absolute production quotas, which can presumably be traced back to the disproportionate mixing in of the isotope and/or different production quotas in various regions of the rumen. The relative differences between the production quotas dependent on the rations, however were approximately the same with both sampling methods, so that they make the comparison of the rations concerning rumen fermentation possible. The production of acetic acid and the total production of fatty acids (C2--C4) correlated closely both with the intake of digestible energy and the intake of digestible organic matter. There was also a highly significant correlation o that they make the comparison of the rations concerning rumen fermentation possible. The production of acetic acid and the total production of fatty acids (C2--C4) correlated closely both with the intake of digestible energy and the intake of digestible organic matter. There was also a highly significant correlation o that they make the comparison of the rations concerning rumen fermentation possible. The production of acetic acid and the total production of fatty acids (C2--C4) correlated closely both with the intake of digestible energy and the intake of digestible organic matter. There was also a highly significant correlation between the relation of acetic and propionic acid in the rumen fluid and the quotient from acetic and propionic acid produced. In contrast to this, a significant relation between the concentration of fatty acids and the production of fatty acids could not be ascertained. Soybean oil and coconut fat brought about a slightly better utilisation of the fat-free organic matter for the production of fatty acids in the rumen. This could mainly be traced back to the increased production of propionic acid. The production of acetic acid per kg fat-free organic matter was insignificantly reduced. A reduced quota of roughage in the ration as well as the use of feed fats resulted in a decrease in the production of acetic acid and an increase in the production of propionic acid. The influence of the quota of roughage, however, was bigger than that of the use of fats. When rations rich in roughage were given, the share the energy contained in the total fatty acids has in the total of the digested energy was, on an average of both animals, slightly lower in comparison to rations rich in concentrated feed. However, the reason for this is not to be found in a lower share the energy digested in the stomachs has in the total of digested energy but in a higher amount of fermentation losses with a nutrition rich in roughage.     

The use of a partly-hydrolysed straw meal in the feeding of weaned piglets. 2. Concentration and production of volatile fatty acids in the large intestine by the use of test rations with various portions of straw

The ad libitum influence of various quotas of partly hydrolysed straw meal (PHSM) on the fermentation and production of volatile fatty acids (VFA) in the colon in the measuring periods 2nd and 8th weeks of keeping was checked within a feeding experiment with weaned piglets of the country species (42nd-98th day of life; 1st-8th week of keeping). The straw hydrolysis product was fed in a parallel experiment without or after neutralization with CaCO3 in quotas of, 5, 10 and 15% related to dry matter in comparison to the feeding of sole concentrate feed. The measuring in the 2nd week of keeping (adaptation phase) was blurred by the diarrhea in the groups with regard to the concentration, production and molar proportion of VFA. The concentration and production quota of VFA was diminished and the C2:C3 relation as well as the molar quota of branched-chain fatty acids increased in the comparison of the groups above all under the feeding conditions of the sole use of concentrate and--less distinctly--of quotas of 5% PHSM (insufficient dietetic effect) in the feed mixture. Measuring in the 8th week, in which diarrhea did not play a role in any of the groups, showed a significant, ration specific influence on the fermentation pattern of VFA. With the increasing quota of PHSM in the feed mixture (x) a significantly positive relation with the molar acetate quota (y) could be calculated (y = 52.6 + 0.36x;r = 0.50). The C2:C3 relation after sole concentrate feeding rose to 2.6:1 at a 15% PHSM integration. In this, the molar increase of acetate was predominantly linked with a decrease of the butyrate and valerate quotas. A falling tendency of the molar iso-acid quota in the colon digesta was registered with the growing straw quota in the feed mixture. The daily production quota of VFA varied in the measuring period in the 8th week of keeping between 400 and 800 mmol/animal.d without an ascertainable influence of the crude fibre quota of the straw. In comparative calculations with other test results, however, a significant positive correlation between the daily intake of digestible organic matter and the production of VFA in the large intestine could be proved.     

日粮精粗比对奶牛瘤胃内环境的影响

本文主要讨论了日粮精粗比对奶牛瘤胃内环境的影响,包括对瘤胃细菌菌群数量、瘤胃pH值、瘤胃内容物稀释率和外流速度、氨态氮浓度以及挥发性脂肪酸的影响。     

Rumen fermentation response to a direct-fed xylanase enzyme preparation from Thermomyces lanuginosus in sheep

A study was conducted to obtain data on the effects of a fungal fibrolytic enzyme preparation (Rumino-zyme, with 250 FXU/g xylanase activities) from Thermomyces lanuginosus on some rumen fermentation parameters in sheep. Ruminal fluid samples were taken just before the morning feeding and then 2 h and 4 h after feeding. Xylanase activity, pH, concentration of ammonia and volatile fatty acids were measured. The enzyme supplementation did not affect the pH but increased the xylanase activity and the total VFA concentration of the rumen fluid. The molar proportion of acetate increased, propionate was not affected and butyrate decreased after enzyme administration. The concentration of ammonia also decreased after supplementation with the enzyme product. It can be concluded that the xylanase enzyme preparation from T. lanuginosus induced favourable changes in the major rumen fermentation parameters in sheep.     

Ammonia, pH and volatile fatty acids in the bovine rumen after feeding with hay.

The effect of feeding level and interval between feedings on the fermentation pattern in the bovine rumen have been investigated in experiments with hay. The animals were completely adapted heifers fitted with rumen cannulas, and the parameters measured were ammonia, pH, volatile fatty acids (VFA) and non-glucogenic/glucogenic ratio (NGGR) in the VFA mixture.Increasing feeding levels, ranging from 2/3 to 4/3 of maintenance level, resulted in higher average concentrations of VFA and lower pH in the rumen fluid. Further the highest level of intake caused a considerable diurnal variation in the pH and the concentration of total VFA, and increased the variation in the molar composition of the VFA mixture.Three feeding intervals ranging from 8 to 16 hrs., with hay administered at maintenance level, caused no changes in the fermentation pattern.Typical variations in the concentrations of ammonia and valeric acid as related to time after feeding were demonstrated, but the concentrations of the branched-chain fatty acids in the rumen fluid were found to be quite constant.It may be concluded that a representative mean value of the parameters measured, except for ammonia and valeric acid, may be based on relatively few samples when feed intake does not exceed maintenance level, whereas sampling every hour is required at higher feeding levels.     

Influence of yeast (Saccharomyces cerevisiae as Yea-Sacc or Levaferm) on in Sacco dry matter degradability and ruminal parameters of variously fed small ruminants.

Two series of experiments with rumen fistulated castrated male sheep and goats were carried out. In experiment I three sheep each consumed rations rich in concentrate (700 g concentrate, 200 g chopped wheat straw) or roughage (700 g artificially dried ryegrass, 200 g chopped wheat straw per animal per day) and supplemented with 0, 1, 2 or 4 g Yea-Sacc (Saccharomyces cerevisiae; USA) per sheep per day. In experiment II three sheep were fed with 1000 g artificially dried ryegrass and 200 g concentrate, three goats consumed 750 g ryegrass and 150 g concentrate. 0, 0.5, 1 or 2 g Levaferm (Saccharomyces cerevisiae; Germany) per animal per day were added. Rations of all animals were supplemented with minerals and vitamins. After 14 days of feeding wheat straw, ammonia treated wheat straw and artificially dried grass (exp. I) or wheat straw and artificially dried grass (exp. II) were incubated in nylon bags in the rumen for 6, 12, 24, 48 and 72 hours. At the end of the experiments rumen fluid was taken via cannulae and parameters of rumen fermentation were measured. Higher levels of added Yea-Sacc decreased in sacco dry matter degradability of all incubated feeds. Depression was much higher if Yea-Sacc was added to the concentrate ration (overall mean for 24, 48 and 72 h incubation time: 55.1, 47.1, 46.1 and 44.5 for 0, 1, 2 and 4 g Yea-Sacc) than to the roughage diet (58.7, 56.3, 55.0 and 54.1%). Levaferm did not significantly influence the rumen dry matter degradability of incubated feeds (overall mean for 24, 48, and 72 h incubation time: 64.0; 64.9; 64.9 and 64.2% for sheep; 63.0; 63.2; 63.2 and 61.6% for goats, if added with 0, 0.5, 1 and 2 g Levaferm per animal per day). Rumen pH, concentration of volatile fatty acids and molar concentration of fatty acids in rumen fluid were not significantly influenced by added yeasts. More research seems necessary to find out the mode of action of yeast and to quantify and to reproduce the effects of added yeast.     

TMR制作粒度对肉牛增重与瘤胃微生物发酵的影响

为研究不同粒度全混合日粮(TMR)对肉牛增重和瘤胃发酵的影响,试验选取新疆褐牛(♂)与哈萨克牛(♀)杂交一代、体重为(305.6±5.6)kg的公牛70头,随机分为2组,预试期14 d,正试期44 d。日粮为不同搅拌时间的TMR,使用宾州筛进行粒度分布测定。对照组TMR搅拌时间为30 min,平均粒度为7.1 mm;试验组TMR搅拌时间为40 min,平均粒度为6.1 mm。结果表明:与对照组相比,试验组第1层(>19 mm)比例下降了6.3个百分点,第2层(>8 mm)和底层(≤1.18 mm)比例下降了3个百分点(P<0.01);结合剩料粒度分析结果研究发现,虽然延长搅拌时间后没有提高TMR总采食量,但提高了肉牛对TMR中粒度大于8 mm长纤维饲料的进食量,并提高了肉牛育肥全期平均日增重(P<0.05),饲料转化效率提高了12.7%(P=0.01);对TMR及宾州筛各层样品采用体外瘤胃发酵测试结果表明,延长TMR搅拌时间对体外干物质消化率、发酵产气量与产气速率、氨氮和挥发性脂肪酸(VFA)生成量无影响;但随着筛分粒度的下降,总VFA生成量升高(P=0.02),其中乙酸比例下降而丁酸比例升高(P<0.05)。综上所述,通过延长搅拌时间降低TMR粒度虽未能提高采食量,但可促进肉牛生长继而显著提高饲料转化效率,并有利于维持瘤胃微生物的正常发酵功能。     

向日葵秆和向日葵盘对绵羊营养价值的评定

试验选用6只体重28 kg左右安装永久瘤胃瘘管的甘肃高山细毛羯羊, 采用3×3无重复拉丁方设计, 通过消化代谢试验, 对向日葵秆和向日葵盘对绵羊的营养价值进行了评定。结果表明:向日葵秆和向日葵盘风干样品中干物质、粗蛋白质、粗脂肪、粗纤维、中性洗涤纤维、酸性洗涤纤维、粗灰分、钙、磷分别为90.73%, 5.72%, 0.89%, 30.15%, 53.09%, 39.40%, 11.61%, 0.84%, 0.13%和89.63%, 11.84%, 2.13%, 12.48%, 23.51%, 15.41%, 14.04%, 0.97%, 0.29%;向日葵秆和向日葵盘对绵羊干物质消化率、氮消化率、氮存留率、有机物消化率、中性洗涤纤维消化率、酸性洗涤纤维消化率、钙消化率、磷消化率及消化能分别为61.61%, 65.37%, 34.72%, 65.19%, 48.18%, 44.89%, 29.10%, 26.07%, 8.75 MJ/kg和70.96%, 69.57%, 41.60%, 76.26%, 60.87%, 58.60%, 37.98%, 44.75%, 9.97 MJ/kg。饲粮中添加向日葵秆对绵羊瘤胃液中乙酸摩尔比及氨氮含量产生了显著的影响(P<0.05),对瘤胃液pH、总挥发性脂肪酸、丙酸摩尔比、丁酸摩尔比、其他酸摩尔比及瘤胃液中总氮、尿素氮、蛋白氮浓度均无显著影响(P>0.05);饲粮中添加向日葵盘对绵羊瘤胃液乙酸摩尔比、丙酸摩尔比和乙酸/丙酸产生了显著的影响(P<0.05),对pH、总挥发性脂肪酸、丁酸摩尔比、其他酸摩尔比和瘤胃液含氮量无显著影响(P>0.05)。     

银合欢叶粉中含羞草素在牛瘤胃内代谢降解的研究

6头从未接触过银合欢叶粉饲料的杂交黄牛被用于研究含羞草素在瘤胃中的代谢降解，试验牛第1～26天日采食2kg银合欢叶粉，27－29天增加到4kg，30天以后日采食量达7kg。试验第1、8、15、22、28和31天为瘤胃液采样日期，采样日期投喂银合欢叶粉后第0、2、4、6、8、12和24小时为采样时间。瘤胃液样本经处理后测定含羞草素、总挥发性脂肪酸、氨态氮浓度以及各种挥发性脂肪酸的比例。试验结果表明：试验牛瘤胃微生物开始接触银合欢叶粉不久即具有降解含羞草素的能力，喂后1小时瘤胃中含羞草素达到峰值浓度，喂后2小时即下降60％以上，含羞草素并不影响瘤胃发酵程度和发酵类型。     

日粮硝酸盐水平对湖羊瘤胃硝态氮动态消失率、发酵参数及血液高铁血红蛋白含量的影响

本试验研究日粮硝酸盐的添加量对湖羊瘤胃还原硝态氮程度和对发酵参数及血液高铁血红蛋白的影响。试验选取6头湖羊,采用随机区组试验设计,每期分别饲喂含0%,1%,2%,3%,4%,5%硝酸钾的日粮。测定喂后0,0.5,1.0,1.5,2.0,4.0,6.0,8.0 h瘤胃液硝酸盐和亚硝酸盐含量及瘤胃发酵参数。晨饲后2.0 h通过颈静脉采血,测定高铁血红蛋白含量。结果表明,湖羊在采食1.0 h后硝酸盐含量达到最高(0.952.14 g/L),之后快速消失,亚硝酸盐含量在喂后1.5 h达到最高(0.936.22 μmol/L),之后降低。高铁血红蛋白的含量随硝酸盐添加量的增加而显著升高(P<0.01),最高达0.32%。添加硝酸盐显著提高瘤胃液pH值(P<0.01)和2.0 h的氨态氮含量(P<0.01)以及乙酸/丙酸,添加量高于3%会降低微生物蛋白和总挥发性脂肪酸的浓度,2%的硝酸盐添加量微生物蛋白和总挥发性脂肪酸的合成量最高,最有利于微生物发酵。