The dynamics of the content of ammonia and volatile fatty acids in the rumen fluid during the use of dry feed rations in the cow

The development of the pH-value, the molar quota of volatile fatty acids and of the NH3 content in the change from silage rations to dried rations on the basis of pelleted feed and in dependence on the time after the beginning of feeding was tested in studies of the rumen fluid of four cows in order to explain the causes of the very low NH3 content of the rumen fluid in feeding experiments with rations based on pelleted straw-concentrate mixtures. An influence of the ration type and the time after the beginning of feeding on the molar quota of the individual volatile fatty acids and the NH3 content was ascertained. The ration type tested can cause an NH3 content in the rumen fluid below 1 mmol/l.     

Effect of donor animals and their diet on in vitro nutrient degradation and microbial protein synthesis using grass and corn silages

Two nonlactating cows and two wether sheep, all fitted with a permanent cannula into the rumen, were fed either hay plus concentrate, grass silage or corn silage to study the effect of the donor animal and its diet on in vitro fermentation and microbial protein synthesis. Rumen inoculum was obtained before the morning feeding. Grass silage or corn silage was incubated in a semi‐continuous rumen simulation system for 14 days. Four replicated vessels were used per treatment. Degradation of crude nutrients and detergent fibre fractions as well as microbial protein synthesis and the production of volatile fatty acids were studied. Additionally, total gas and methane production was measured with a standard in vitro gas test. Gas production and methane concentration was higher when the inoculum used was from sheep than that from cows. The donor animal also affected the degradation of organic matter and ether extract as well as the amount of propionate and butyrate, and the acetate‐to‐propionate ratio. The effect of the diet fed to the donor animal on fermentation was much greater than the effect of the donor animal itself. Feeding hay plus concentrate resulted in higher gas production and degradation of acid detergent fibre, but in lower degradation of ether extract and reduced microbial protein synthesis. Additionally, the pattern of volatile fatty acids changed significantly when the diet of the donor animals was hay plus concentrate or one of the silages. These results show that in vitro fermentation and microbial protein synthesis is different when based on inoculum from either cattle or sheep. The diet fed to the donor animal is more important than the animal species and is probably mediated by an adjusted microbial activity. With regard to standardized feed evaluations, these results further support the need to harmonize in vitro approaches used in different laboratories.     

体外法研究脂多糖对瘤胃发酵的影响

本试验旨在通过体外法研究脂多糖(LPS)对瘤胃发酵的影响。选取4头健康、体况相近、安装有永久性瘤胃瘘管的荷斯坦奶牛用于瘤胃液的采集。试验分为对照组(不添加LPS)和试验组(添加LPS 100 000 EU/m L),分别在发酵2、4、8、12、24 h后取样,测定发酵液p H及挥发性脂肪酸、氨态氮、微生物蛋白浓度。结果表明:随着发酵时间的延长,对照组与试验组发酵液p H逐渐下降,发酵液总挥发性脂肪酸、氨态氮、微生物蛋白浓度及乙酸、丙酸、丁酸含量逐渐增加,对照组与试验组之间均无显著差异(P0.05),但在8、24 h试验组发酵液p H与对照组相比有降低的趋势(0.05≤P0.10),4、8、24 h试验组氨态氮浓度与对照组相比有降低的趋势(0.05≤P0.10)。结果显示,在体外发酵条件下,添加LPS具有降低发酵液p H以及氨态氮浓度的趋势,但这一影响并不显著。     

气相色谱-质谱联用法测定瘤胃液中的甲酸和其他6种挥发性脂肪酸

本试验旨在建立一种测定瘤胃液中甲酸、乙酸、丙酸、异丁酸、丁酸、异戊酸和戊酸的气相色谱-质谱联用方法。样品选用湘东黑山羊和荷斯坦奶牛的瘤胃液,18000 r/min离心10 min,取上层清液。将上层清液与25%的偏磷酸按照9∶1(v∶v)的比例混合均匀,静置0.5 h后,4℃条件下18000 r/min离心10 min,取上清液过0.22μm滤膜,进行气相色谱-质谱分析。以DB-FFAP毛细管柱进行分离,甲酸、乙酸、丙酸、异丁酸、丁酸、异戊酸和戊酸在9 min内达到基线分离。结果表明:这7种组分色谱峰保留时间的相对标准偏差均小于0.5%,峰面积的相对标准偏差均小于5.0%。甲酸、乙酸、丙酸、异丁酸、丁酸、异戊酸和戊酸分别在0.8~121.0μg/mL、0.3~3081.0μg/mL、0.4~1165.2μg/mL、0.4~275.1μg/mL、0.2~543.0μg/mL、0.5~129.9μg/mL和0.4~271.5μg/mL内线性关系良好,线性相关系数均达到0.998以上,检出限(3倍信噪比)在0.069~0.252μg/mL。山羊和奶牛瘤胃液样品的加标回收率分别为91.8%~103.8%和78.7%~95.2%。本试验建立的测定瘤胃液中甲酸以及其他6种挥发性脂肪酸的气相色谱-质谱联用方法选择性强、样品用量少、操作简单,可为反刍动物瘤胃碳水化合物代谢及甲烷生成的相关研究提供技术支撑。     

Fiber digestion in various segments of the hindgut of horses fed grass hay or silage

We studied in vivo fiber digestibility and fermentation parameters such as volatile fatty acid concentration and in vitro degradation in each segment of hindgut of horses fed timothy hay or silage made from the same sward. Six Thoroughbred horses were fed timothy hay or silage in equal amounts (1.6% of bodyweight per day, bodyweight mean 572 kg) every 3 h per day, then slaughtered. There were no differences between hay and silage in the concentration of the total volatile fatty acids, the apparent digestibility of dry matter, organic matter, and fiber, and in vitro neutral detergent fiber (NDF) disappearance rate in each segment. The total volatile fatty acid concentration and the apparent digestibility of dry and organic matter and fiber differed ( P  < 0.01) depending on the digestive segments. Both for hay and silage, the concentration of total volatile fatty acids in the digesta liquid phase largely increased ( P  < 0.01) from the cecum to the right ventral colon, and kept a constant value from the right ventral colon to the right dorsal colon, and then decreased from the right dorsal colon to the small colon. For dry and organic matter and fiber components, the apparent digestibility changed in the same manner from former to hinder segments of the hindgut. Regardless of diet, dry and organic matter and fiber components showed lower values in the cecum and the right ventral colon and increased ( P  < 0.01) largely from the right ventral colon to the left dorsal colon, then kept constant values in segments to the rear of left dorsal colon. There were no differences in in vitro NDF disappearance among cecum, ventral colon and dorsal colon.     

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.     

Effects of total replacement of corn silage with sorghum silage on milk yield,composition, and quality

Background: In the last years, difficulties occurring in corn cultivation(i.e., groundwater shortages, mycotoxin contamination) have been forcing dairy farmers to consider alternative silages. Some experiments conducted on lactating cows have proven that the total replacement of corn silage with sorghum silage did not reduce milk yield.However, this kind of substitution involves supplementing sorghum-based diets with grains, to compensate for the lower starch content of sorghum silage compared to corn silage. Change of silage type and inclusion of starch sources in the diet would influence rumen fermentations, with possible effects on milk composition(i.e., fatty acid profile) and coagulation properties. A worsening of milk coagulation properties would have a negative economic impact in Italy, where most of the milk produced is processed into cheese.This study was designed to compare milk composition and quality, with emphasis on fatty acid profile and coagulation properties, in dairy cows fed two diets based on corn or sorghum silage.Results: The sorghum diet reduced milk yield(P = 0.043) but not 4% fat corrected milk(P = 0.85). Feeding sorghum silage did not influence milk contents of protein(P = 0.07) and lactose(P = 0.65), and increased fat content(P = 0.024).No differences emerged for milk concentrations of saturated(P = 0.61) and monounsaturated fatty acids(P = 0.50),whereas polyunsaturated fatty acids were lower(P 0.001) for the sorghum diet. Concentrations of n-6(P 0.001) and n-3 fatty acids(P = 0.017) were lower in milk of cows fed the sorghum diet. Milk coagulation properties did not differ between the two diets, except the "a30"(the curd firmness, expressed in mm, 30 min after rennet addition), that was lower(P = 0.042) for the sorghum diet.Conclusions: Feeding a forage sorghum silage, properly supplemented with corn meal, as total replacement of corn silage maintained milk composition and did not influence negatively milk coagulation properties, which have a great economic relevance for the Italian dairy industry. Thus, silages obtained from forage sorghums could have a potential as substitute of corn silages in dairy cow diets.     

Feeding flaxseed in grass hay and barley silage diets to beef cows increases alpha-linolenic acid and its biohydrogenation intermediates in subcutaneous fat

The objective of the study was to determine temporal fat deposition and fatty acid profiles in beef cows fed hay- or barley silage-based diets, with or without flaxseed. Crossbred cull beef cows (n = 64, >30 mo of age, 620 ± 5 kg) were removed from grassland pastures, randomly assigned to 16 pens, and given ad libitum access to 50:50 (wt/wt, DM basis) forage:concentrate diets containing 0 or 15% ground flaxseed (DM basis, 5.2% added fat). Diets consisted of hay control (HC), hay+flaxseed (HF), barley silage control (SC), and silage+flaxseed (SF). Backfat biopsies were obtained from each cow at 0, 6, and 12 wk, and at slaughter (~20 wk) to assess fatty acid composition. With the exception of feed efficiency, flaxseed × forage interactions were not significant for backfat accumulation or performance parameters. Flaxseed improved (P < 0.01) feed conversion when supplemented to hay-based diet and increased ADG (P = 0.03), resulting in a heavier (P = 0.02) BW. Compared with hay, barley silage increased (P < 0.01) DMI, ADG, and feed efficiency. Subcutaneous fat contained 0.68% n-3 fatty acids at wk 0, and reached 0.68, 0.81, and 0.94% in HF cows after 6, 12, and 20 wk, respectively (Y(n-3) = 0.0133X + 0.6491, r = 0.87). It was 0.67% at wk 0, and reached 0.65, 0.77, and 0.90% in SF cows after 6, 12, and 20 wk, respectively (Y(n-3) = 0.0121X + 0.6349, r = 0.75). In contrast, weight percentage of n-3 fatty acids decreased in HC cows from 0.63, 0.50, and 0.47, to 0.43%, and in SC cows from 0.63, 0.40, and 0.36, to 0.33% over the 20 wk. A forage × flaxseed interaction (P < 0.05) occurred for many of the α-linolenic acid (ALA) biohydrogenation intermediates, including vaccenic acid (C18:1 trans-11) and CLA (combined C18:2 trans-7,cis-9 and cis-9,trans-11) in plasma, and in subcutaneous fat this also included non-CLA dienes. Concentrations of most α-linolenic acid biohydrogenation intermediates were greater when feeding flaxseed with hay. In conclusion, forage source altered plasma concentrations and rate of accumulation of ALA biohydrogenation products in subcutaneous fat from beef cows fed flaxseed. Factors responsible for this response are yet to be defined, but may include forage-mediated changes in ruminal biohydrogenation of ALA, as well as alterations in fatty acid metabolism and deposition.     

不同粗饲料日粮对西门塔尔繁殖母牛瘤胃发酵和血液指标的影响

[目的] 分析不同粗饲料日粮对西门塔尔繁殖母牛瘤胃液pH值、瘤胃挥发性脂肪酸含量及血液指标的影响。[方法] 选择体重相近的西门塔尔繁殖母牛18头,按同质原则分为3组,每组6头。日粮1组粗饲料为干玉米秸秆,日粮2组粗饲料为全株玉米青贮,日粮3组粗饲料为全株玉米青贮+干玉米秸秆。预试期14 d,正试期42 d。采集试验牛的瘤胃液和血液样本,进行瘤胃液pH值、挥发性脂肪酸（volatile fatty acid,VFA）含量及血液指标测定。[结果] 3组繁殖母牛的瘤胃液pH值差异不显著（P> 0.05）。全株玉米青贮组的瘤胃内乙酸含量显著（P<0.05）高于干玉米秸秆组,全株玉米青贮组和全株玉米青贮+干玉米秸秆组的瘤胃内丙酸含量显著（P<0.05）高于干玉米秸秆组,全株玉米青贮组的瘤胃内正丁酸和异丁酸含量显著（P<0.05）高于其他组。干玉米秸秆组的血清SOD活力和T-AOC活力显著（P<0.05）低于其他组,GSH-Px活力显著（P<0.05）低于全株玉米青贮+干玉米秸秆组。干玉米秸秆组血清中的铁（Fe）和锌（Zn）含量显著（P<0.05）低于全株玉米青贮组,干玉米秸秆组和全株玉米青贮组血清中的硒（Se）含量显著（P<0.05）高于全株玉米青贮+干玉米秸秆组。干玉米秸秆组血清中VD和VE含量显著（P<0.05）低于其他组。[结论] 饲喂以全株玉米青贮或者全株玉米青贮+干玉米秸秆为粗饲料的日粮,西门塔尔繁殖母牛的瘤胃发酵和血液生化指标优于饲喂以干玉米秸秆为主要粗饲料的日粮。结合饲养成本和农区粗饲料供给情况,生产中推荐全株玉米青贮+干玉米秸秆的粗饲料饲喂模式。     

Effects of different source additives and wilt conditions on the pH value,aerobic stability,and carbohydrate and protein fractions of alfalfa silage

To improve the silage quality and reduce the silage additive cost, the present experiment was designed to evaluate the potential of applying the fermented juice of epiphytic lactic acid bacteria (FJLB) as an additive in alfalfa silage. The effects of FJLB on the fermentation quality, carbohydrate and protein fractions, and aerobic stability of alfalfa silage wilted under five different conditions were investigated and compared with commercial lactic acid bacteria (CLAB) and the control. The FJLB application decreased the pH value, the volatile fatty acids and non‐protein nitrogen content, and the loss of sugar by 9.9%, 22.9%, 19.6% and 9.6%, respectively; it increased the lactic acid concentration by 29.5% and the aerobic stability by 17 h in comparison to the control. The FJLB application also decreased the pH value (4.44 vs. 4.66) and volatile fatty acid content (38.32 vs. 44.82) and increased the lactic acid concentration (68.99 vs. 63.29) in comparison to the CLAB‐treated silage. However, the FJLB treatment had lower aerobic stability (254 h vs. 274 h) than the CLAB treatment. The FJLB application improved silage quality in comparison to the control; in addition, its effect as a fermentation stimulant may be comparable to or even better than CLAB.     

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.     

Rumen fermentation,milk production and conjugated linoleic acid in the milk of cows fed high fiber diets added with dried distillers grains with solubles

The effects of corn dried distillers grains with solubles (DDGS) feeding on rumen fermentation and milk production in cows were evaluated using diets high in neutral detergent fiber (NDF, 45.9–46.6%). The control diet (Control) consisted mainly of hay, corn silage and concentrates. In the experimental diets, the concentrates were replaced with DDGS as 10% dry matter (DM) (10%DDGS) and 20% DM (20%DDGS). Eight cows were used for each 14‐day treatment period. Effect of DDGS feeding on DM intake was not significant. Ruminal volatile fatty acids and ammonia‐N at 5 h after feeding of 20%DDGS were decreased compared to Control, whereas protozoal count at 2 h after feeding of 20%DDGS was higher than that of 10%DDGS. Milk yield of cows fed DDGS diets was greater than that of Control, although percentages of milk protein and solids‐not‐fat were decreased by DDGS diets. The proportions of C10:0, C12:0, C14:0 and C16:0 in the milk fat decreased, and those of C18:0, C18:1, C18:2 and cis‐9, trans‐11 conjugated linoleic acid (CLA) increased markedly with elevated DDGS. Increase in trans‐11 C18:1 was observed in the rumen fluid at 5 h after feeding. These findings suggest that DDGS feeding enhanced milk yield, as well as CLA synthesis under a high dietary NDF condition.     

Effect of replacing corn with brown rice grain in a total mixed ration silage on milk production,ruminal fermentation and nitrogen balance in lactating dairy cows

Nine multiparous Holstein cows were used in a replicated 3 × 3 Latin square design to determine the effects of substituting corn grain with brown rice (BR) grain in total mixed ration (TMR) silage on milk yield, ruminal fermentation and nitrogen (N) balance. The TMR silages were made from the ensiling of TMR containing (dry matter basis) 50.1% forage in rice silage and corn silage combination, and 49.9% concentrate. The grain portion of the diets contained 31.2% steam‐flaked corn, 31.2% steam‐flaked BR or an equal mixture of corn and BR. Dietary treatments did not affect dry matter intake, milk yield and milk fat, protein and lactose yields. The ruminal pH and total volatile fatty acid concentrations were not affected by dietary treatment. The urinary N excretion decreased linearly (P < 0.01) in response to increased levels of BR, with no dietary effect on N intake, N secretion in milk and fecal N excretion. Our results indicate that steam‐flaked BR is a suitable replacement for steam‐flaked corn in dairy cow diets, and that it can be included in rations to a level of at least 31.2% of dry matter without adverse effects on milk production, when cows were fed rice silage and corn silage‐based diets.     

Plasma and Follicular Fluid Fatty Acid Profiles in Dairy Cows

Composition of follicular fluid to which the preovulatory follicle is exposed may be one of the major factors determining subsequent fertility, as fatty acids are a precursor of hormones involved in dominance, ovulation and atresia mechanisms. The objective of this paper is to observe fatty acid profiles in various lipid classes according to estrogenic activity of follicles. For each of the 18 cows, we analysed plasma and follicular fluid fatty acid profiles of phospholipids, non-esterified fatty acid (NEFA), cholesteryl esters and triglycerides fractions. Follicles were classified as active (ratio oestrogen to progesterone E2/P4 > 1) and inactive (E2/P4 < 1). For seven cows, we get both types of follicles, six had only one active follicle and five cows had only one inactive follicle. The NEFA profile for palmitic acid, stearic acid, oleic acid, linoleic acid, C20:3n6, arachidonic acid and docosapentaenoic acid (DPA; p < 0.001) is different between inactive and active follicles and plasma. Compared with active follicular fluid and plasma, follicular fluid of inactive follicles showed lower stearic acid, higher oleic acid, arachidonic acid and DPA (p < 0.05) in phospholipids. No significant differences were observed in the cholesteryl ester fraction, which is composted mainly of linoleic acid. Triglyceride concentrations were too low to get reliable results. This study suggests that follicles have a specific fatty acid metabolism depending on oestrogen activity.     

The protozoa population in the rumen of fattening bulls fed varying feed and the effect of artificial transfer of protozoa]

High protozoa concentrations were found in the ruminal fluid of fattening bulls weighing 400 kg which were raised for the first five months of age in a large-size calf-raising plant. The ruminal fluid of these bulls, however, contained no protozoa of the group Holotricha. If the animals were fed a mixture of concentrates and pelleted straw (pH 6, 12.5 mMole of volatile fatty acids per 100 ml) 1 ml of the ruminal fluid was found to contain 827,000 protozoa whereas if the animals received rations rich in concentrates (pH 5.8, 14 mMole of volatile fatty acids) 1 ml of ruminal fluid contained only 578,000. Through protozoa transfer carried out by infusing 41 of a mixture of ruminal fluid from other cows per animal it was possible to settle other species, viz. Isotricha, Dasytricha and Ophryoscolex; this, in turn, produced a concomitant decrease in the number of Entodinium and a noticeable decline in the total protozoa population. Further work will be necessary to find out whether it would be advisable to influence the protozoa population of growing cattle kept in large-size cow plants in similar ways as described above.     

Effect of brewer's grain on rumen fermentation, milk production and milk composition in lactating dairy cows

Six lactating Holstein cows were divided into two groups (n = 3) and used in a double reversal trial with three periods of 14 days each to evaluate the rumen fermentation, milk production and milk composition of cows fed brewer's grain (BG). The control diets contained 14% chopped Sudangrass hay, 24% corn silage, 18% alfalfa hay cube, 34% concentrate mixture‐1 and 10% concentrate mixture‐2 (wheat bran, soybean meal and cottonseed). In the experimental diet, wet BG replaced the concentrate mixture‐2. The protozoal population, concentration of ammonia‐N and volatile fatty acids in the ruminal fluid did not differ between the control and BG diets. The molar percentage of acetic acid was significantly higher (P < 0.05) with the BG diet at 5 h after feeding. The milk yield, the percentage of protein, lactose, solids not‐fat and somatic cell counts of milk did not differ between the two diets. The percentage of milk fat tended to increase with the BG diet. The BG diet significantly increased the proportions of C18:0 and C18:1 in milk fat (P < 0.01, P < 0.05, respectively) and tended to increase that of conjugated linoleic acid.     

A note on the effect of dietary proportions of kale (Brassica oleracea) and grass silage on rumen pH and volatile fatty acid concentrations in dry dairy cows

The objective of this study was to evaluate the effect of varying proportions of dietary kale on rumen pH and volatile fatty acid production. Four pregnant dry dairy cows permanently fitted with ruminal cannulae were randomly assigned to four kale: grass silage dietary proportions (0:100, K0; 60:40, K60; 85:15, K85 and 100:0, K100) on a dry matter basis in a 4 × 4 Latin Square design with four 20 day periods. Cows were acclimatised for 15 days, followed by a five-day period of experimental sampling and measurement. Internal pH meters were installed to continuously monitor rumen pH while rumen liquor collection tubes were used to sample rumen liquor for volatile fatty acid analysis at 0, 4, 8 and 12 h after feeding on each sampling day. Cows on treatment K85 had a lower (P < 0.001) ruminal pH compared to cows on treatments K100, K60 or K0 (6.26, 6.32, and 6.32 vs. 5.91, respectively). While a gradual decrease in rumen pH was observed over an eight-hour period for K85 before recovery, offering K100 did not reduce rumen pH below 6.0 or induce acidosis. Increasing the dietary proportion of kale did not affect (P > 0.05) acetate:propionate ratio production (3.71, 3.65, 3.86, 3.78 mmol L^− 1 for K0, K60, K85 and K100, respectively). Offering cows K60 had increased (P < 0.05) rumen VFA concentration (71.67 mmol L^− 1) relative to K0 (53.45 mmol L^− 1), while offering K85 and K100 had no affect on rumen VFA concentration (61.74 and 59.35 mmol L^− 1) (Table 2). Offering dry cows K100 relative to K0 reduced dry matter intake by 17.5% (7.32 vs. 8.87 kg DM day^− 1, respectively) which may be associated with the presence of S-methyl-L-cysteine sulphoxide which can cause haemolytic anaemia and depressed DM intake. The results suggest that increasing the dietary proportion of kale was associated with a progressive decrease in dry matter intake but with minimal effects on rumen pH, total volatile fatty acid concentration and individual volatile fatty acid proportions.     

Feeding value of total mixed ration silage with spent mushroom substrate

Six wethers were used in a digestibility experiment arranged as replicated 3 × 3 Latin square to evaluate the nutritive value of total mixed ration (TMR) silages that were made from ensiling of TMR containing 0, 6.5 and 13.0% (dry matter basis) of spent mushroom substrate (SMS) for 45 days (treatments denoted as CSMS, LSMS and HSMS, respectively). The amount of SMS replaced the same amount of timothy hay in the respective TMR. All TMR were well preserved as indicated by their low pH, low ammonia‐N and high lactic acid contents. Increasing levels of SMS in the TMR silage quadratically reduced (P < 0.05) nutrient digestibility with the exception of ether extract. The difference of total digestible nutrients and digestible energy contents between LSMS and CSMS TMR silage were less than those between LSMS and HSMS. Increasing concentration of SMS in the ration tended to decrease content of total volatile fatty acids in rumen fluid but increased the ratio of acetate to propionate and pH. The study suggests that a SMS level of 6.5% in the diet DM can be recommended for silage based TMR.     

甘露寡糖对围产期奶牛瘤胃微生物区系的影响

试验旨在研究饲粮中添加不同水平的甘露寡糖(MOS)对荷斯坦奶牛围产后期瘤胃微生物区系的影响.选取60头荷斯坦奶牛,随机分4组,每组15头.对照组饲喂基础饲粮,低、中、高剂量组分别在基础饲粮基础上添加5、10、15 g/(头·d)MOS.结果 显示,随着MOS添加量的增加,奶牛产后21 d瘤胃液中微生物蛋白含量、总挥发性...     

An analysis of the buffer system in the rumen of dairy cattle.

A method is presented for the analysis of buffer systems in the rumen using the first derivation of titration curves. Bicarbonate and volatile fatty acids (VFA) are the main components of the buffering system in the rumen fluid of dairy cattle under widely different feeding conditions. Phosphate from saliva is of little importance as a buffer, but neutralizes acids produced in the rumen. After studying five cows during the peripartal period a spontaneous and transient increase in the concentrations of VFA and a soluble marker (PEG) as well as a drop in pH and in the bicarbonate concentrations not related to feeding was observed in two animals that were sampled several hours before parturition. The potential risk of provoking rumen disturbances upon feeding animals close to the time of parturition, when buffering capacity may be minimal, is stressed.