Effects of erythromycin on myoelectric activity of the spiral colon of dairy cows

The effects of erythromycin on myoelectric activity of the spiral colon of dairy cows were investigated in a prospective study. Four Simmental x Red-Holstein crossbred cows of similar body weight and condition with seven pairs of bipolar electrodes implanted in the intestine (one each in the distal ileum, caecum and proximal colon, and four in the spiral colon) were included. Erythromycin lactobionate (1 mg kg(-1)) and 0.9% sodium chloride solution (NaCl) were administered to each cow in a random order. Erythromycin was diluted with NaCl and both treatments were administered slowly intravenously over a period of 5 min 1 h after onset of a phase III of the bovine colonic migrating myoelectric complex (bcMMC). A 3-6-day washout period was scheduled between trials. Significant differences between the results of the treatments were observed for spike duration in phase I as well as for spike duration and duration of spiking activity during phase II of the second bcMMC, which were significantly higher after erythromycin treatment than after NaCl. These findings suggest an indirect effect of erythromycin on colonic motility in cattle.     

Myoelectric activity of the spiral colon in dairy cows

OBJECTIVE: To describe myoelectric activity of the spiral colon in healthy cows. ANIMALS: 7 lactating Simmental X Red-Holstein crossbred cows. PROCEDURE: Cows were implanted with 7 pairs of bipolar silver electrodes (4 in the spiral colon and 1 each in the cecum, distal part of the ileum, and proximal loop of the ascending colon [PLAC]). Myo-electric activity was recorded during 4 days for each cow. Patterns were analyzed, using computer-based methods. RESULTS: Myoelectric activity of the spiral colon was closely associated with motility of the ileum and PLAC and showed the typical organization of migrating myoelectric complexes (MMC). The MMC in the bovine spiral colon (bcMMC) had a mean +/- SD duration of 188.6 +/- 30.8 minutes and was divided into 4 phases. Phases I and II lasted 11.3 +/- 1.4 and 159.4 +/- 33.3 minutes, respectively. Phase III (duration, 5.4 +/- 1.2 minutes) was characterized by 5.2 +/- 0.9 regular spindles (35.4 +/- 5.4 seconds) and 1 final elongated spindle (137.2 +/- 56.4 seconds). Phase III most commonly (73.8 +/- 16.1%) was followed by phase IV (duration, 173 +/- 3.6 minutes). Propagation velocity of phase III was 4.4 +/- 0.5 cm/min, and 13.6% of bcMMC were incompletely propagated through the spiral colon. CONCLUSIONS: Myoelectric activity of the bovine spiral colon is composed of a recurring cyclic pattern similar to MMC of the small intestine. Data of colonic myoelectric activity in healthy cows will serve as a basis for studies on cecal dilatation and dislocation in cattle.     

脂肪酸添加剂对奶牛瘤胃挥发性脂肪酸和甲烷的影响

21头安装瘤胃瘘管的荷斯坦产奶牛随机分为对照组和试验Ⅰ~Ⅵ组,每组3头,对照组饲喂全混日粮(TMR),试验Ⅰ~Ⅵ组每天饲喂TMR加50.0 g、100.0 g、150.0 g、200.0 g、250.0 g、300.0 g/头复合脂肪酸日粮,主要探讨复合脂肪酸对奶牛瘤胃甲烷(CH4)产量、挥发性脂肪酸(VFA)、氨氮(NH3-N)浓度和pH值及产奶性能的影响。结果,TMR中每天添加150.0~200.0 g/头复合脂肪酸,明显(P<0.05)提高奶牛乳脂率和瘤胃乙酸浓度,显著(P<0.05)降低奶牛的CH4释放量、CH4能/GE值和瘤胃NH3-N浓度,对奶牛的标准乳(FCM)、乳干物质、乳蛋白和乳糖均有提高趋势,能有效地提高奶牛的经济效益和生态效益。     

利用体外培养法研究奶牛瘤胃中奇链支链脂肪酸与微生物菌群的相关性

以纯碳水化合物为体外发酵底物,旨在探讨奶牛瘤胃中奇链支链脂肪酸含量与微生物菌群相对丰度的相关关系。试验选取3头安装永久性瘤胃瘘管的荷斯坦奶牛作为瘤胃液供体,以不同比例的纤维素(F)和淀粉(S)为培养底物(F∶S=0∶100,25∶75,50∶50,75∶25,100∶0)进行体外发酵。于体外发酵6,12,18,24 h采集发酵液并测定奇数和支链脂肪酸含量和微生物菌群相对丰度。结果显示:瘤胃液中奇数直链脂肪酸占总OBCFA的比例最大,且C15及其异构体所占的比例大于C17及其异构体的比例;F∶S对iso C15、anteiso C15、C15、iso C16、iso C17、anteiso C17和C17含量均有显著影响(P<0.05)。白色瘤胃球菌、黄色瘤胃球菌、溶纤维丁酸弧菌、嗜淀粉瘤胃杆菌和牛链球菌相对丰度受F∶S影响(P<0.05)。此外,白色瘤胃球菌和黄色瘤胃球菌的种群数量与iso C15和C15含量正相关(r=0.25～0.70,P<0.05),与iso C16和anteiso C17负相关(r=-0.28～-0.38,P<0.05);而嗜淀粉瘤胃杆菌与iso C15和C15含量负相关(r=-0.26～-0.43,P<0.05),与iso C16和anteiso C17正相关(r=-0.26～0.35,P<0.05);溶纤维丁酸弧菌的种群数量与iso C15、anteiso C15、iso C16、iso C17、anteiso C17和C17呈负相关(r=-0.35～-0.57,P<0.05);而牛链球菌与iso C15、anteiso C15、iso C16、iso C17、anteiso C17和C17呈正相关(r=0.34～0.43,P<0.05);反刍兽新月单胞菌与C15含量正相关(r=0.31,P<0.05),与anteiso C17负相关(r=-0.26,P<0.05)。由此可见,碳水化合物结构能显著影响瘤胃奇链支链脂肪酸的含量,以及纤维分解菌和淀粉分解菌的菌群丰度,并且奇链支链脂肪酸与瘤胃微生物存在相关性,因而可以间接反映细菌种群变化情况。     

The microflora and concentrations of volatile fatty acids in the rumen of cattle fed on single component rations

The composition of the rumen microflora and the volatile fatty acids were examined in cattle free-grazing on grass or stall-fed on hay, grass pellets, oats or dried beet pulp with molasses. Total and viable counts of anaerobic bacteria were highest on the grass feeding, but viable counts as a percentage of total counts were highest when oats or beet pulp with molasses were fed. Counts of cellulolytic bacteria were lowest on these latter 2 diets, and highest on grass or grass pellet diets. Studies of the anaerobic flora showed that the composition in animals fed on grass pellets resembled more that found in animals free-grazing on grass than in those fed on hay. Counts of aerotolerant bacteria were only a small percentage of the total count, but were highest on the hay diet. On this latter diet and on grass-feeding the streptococci (identified as Streptococcus bovis) were predominant, but contrary to expectation, streptococci were found only in small numbers on the oats diet, where coryneform rods were the major type present. Although a period of 4–6 weeks was allowed for the animals to adapt to the feeds, the 2 periods of feeding on oats and dried beet pulp with molasses markedly affected the composition of the rumen flora in the subsequent periods of feeding grass pellets and hay. Ruinen volatile fatty acid analysis showed a propionogenic effect of oats and the highest percentage of butyric acid when beet pulp with molasses was fed. The expected propionogenic effect of grass pellets was not observed.     

Utilization of glucose and long-chain fatty acids in lactating dairy cows fed a fat-enriched diet

The fate of carbon from long-chain fatty acids and glucose in dairy cows which were fed with protected fat was studied using stable isotope technique. The experiment was carried out on two groups of dairy cows (n=16 in each group) during the first 15 weeks of the lactation period. The cows were fed isoenergetic and isoproteinogenous diets based on corn silage. About 1.8 kg of tapioca starch in the diet of the starch group was substituted by about 0.7 kg of rumen protected fat (Ca salts of palm oil and soybean oil) in the diet of the fat group. The carbon atoms of dietary fat were naturally depleted in 13C as compared to carbon atoms of starch. Daily milk performance and lactose output were significantly (P < 0.05) higher among the cows fed with fat diet. In comparison to the starch group, the enrichment of milk fat with 13C was significantly lower, while that of breath CO2 was significantly higher in the fat group (P < 0.05). This means the fatty acids were incorporated into milk fat in preference to metabolic oxidation. Further studies showed that blood glucose is oxidized to a lower extent and is used for the synthesis of lactose to a higher proportion if the cows were fed with the fat diet. The glucose entry rate into the body glucose pool was not different between the diets. In conclusion, the dietary fatty acids perform a glucose sparing effect and improve the glucose supply for the mammary gland.     

硫酸钠对奶牛瘤胃发酵的影响

本文旨在研究不同添加水平的硫酸钠对泌乳中期奶牛瘤胃发酵的影响。试验选用4头体重、胎次、产奶量均相近的荷斯坦奶牛,采用4×4拉丁方设计,试验分4个处理组,添加不同水平的硫酸钠,即0%(对照组)、0.4%(试验1组)、0.8%(试验2组)与1.2%(试验3组),试验分为4期,每期18 d(预试期15 d,正试期3 d)。结果表明:(1)饲粮中添加硫酸钠对瘤胃液pH、NH3-N平均浓度无显著影响(P>0.05);(2)饲粮中添加硫酸钠后,瘤胃内原虫数均有所提高,其中试验2组和试验3组与对照组相比均差异显著(P<0.05);(3)添加硫酸钠的试验2组瘤胃液菌体蛋白浓度与对照组相比显著提高(P<0.05)。结果说明,日粮中添加适量的硫酸钠可以改变瘤胃发酵环境,提高瘤胃液菌体蛋白浓度。     

不同瘤胃细菌培养物添加水平对奶牛瘤胃发酵及BCP含量的影响

本文旨在研究不同剂量的瘤胃细菌培养物对荷斯坦奶牛瘤胃发酵及菌体蛋白(BCP)含量的影响。试验采用单因素试验设计,选用4头装有永久性瘤胃瘘管,体况相近的荷斯坦奶牛,取其瘤胃液混匀,添加不同剂量的瘤胃细菌培养物进行体外培养,分别为:对照组(0 CUF/g),试验Ⅰ组(添加量为3%,4.4×108CUF/g),试验Ⅱ组(添加量为5%,7.8×108CUF/g),试验Ⅲ组(添加量为10%,1.2×109CUF/g),每组分别设2、4、8、12、24、36、48 h 7个指标测定时间点,每个时间点3个重复。结果表明:(1)添加瘤胃细菌培养物使瘤胃液pH有所降低,但始终在6.5～7.0,对瘤胃内环境无不良影响;(2)添加3%的瘤胃细菌培养物显著降低氨态氮(NH3-N)的含量(P<0.05),显著增加了培养液BCP的浓度(P<0.05);(3)添加3%的瘤胃细菌培养物可一定程度增加总挥发性脂肪酸(TVFA)和乙酸浓度,但对其他各挥发性脂肪酸及乙酸/丙酸比值无显著影响。由此可见,添加3%剂量的瘤胃细菌培养物可改变瘤胃的发酵环境,提高BCP浓度。     

The effects of high levels of rumen degradable protein on rumen pH and histamine concentrations in dairy cows

An experiment was conducted to test the hypothesis that the supplementation of crude protein (CP) results in rumen acidosis and increased histamine concentrations in dairy cows. Six ruminally fistulated, non-pregnant dry cows were fed three experimental rations in a replicated 3 × 3 Latin square design. The CP contents in the low-CP, the high rumen undegradable protein (high-RUP) and the high rumen degradable protein (high-RDP) rations were 112, 259 and 266 g/kg dry matter (DM) respectively. The cows were fed 7.7 kg DM of the concentrates and 2.7 kg DM of rice straw. High levels of RDP in the ration significantly increased the ammonia, total volatile fatty acid (VFA) and histamine concentrations in the rumen fluid. However, supplemental CP, whether degradable or undegradable, did not significantly affect the pH of rumen fluid. Plasma urea nitrogen concentration was higher in both high-RDP and high-RUP in relation to cows fed the low-CP ration. The rise in ruminal histamine concentrations was physiologically non-relevant, most likely because rumen pH was not affected by supplemental CP at the installed level of DM intake. Therefore, it can be concluded that the issue of supplemental CP, rumen pH and ruminal histamine concentrations has not yet been settled. Further research is warranted to understand these relationships.     

The effects of diet on water flux and volatile fatty acid concentrations in the rumen of growing beef steers fed once daily

In vivo temporal changes in ruminal liquid flow, liquid volume and VFA concentrations were determined in growing steers following once-daily feeding. Crossbred beef steers (n = 8; 278 +/- 8 kg), used in a crossover design, were trained to consume 180% of their maintenance energy intake within 2 h of either a high-forage (54% hay: 46% concentrate; HF) or high-concentrate (28% hay: 72% concentrate; HC) diet. For each animal on each diet, ruminal VFA concentrations, liquid volumes and liquid dilution rates were determined during a 2-h period before feeding and during three consecutive 2-h periods following feeding. Water was withheld during these periods to observe physiologically rather than behaviorally induced changes. At equal energy intakes, diet alone had no effect on VFA concentrations (P greater than .10), although changes in total VFA, acetic and isobutyric acids differed during the time periods following feeding due to diet (diet x time period interaction; P less than or equal to .10). Ruminal volume and dilution rate were altered in a reciprocal manner due to diet, with greater volumes and lower dilution rates observed in HC than in HF steers. Differences among time periods were observed for dilution rate and propionic acid concentrations. In general, these differences can be explained by comparison of the prefeeding time period with the postfeeding time periods. A numerical, but not statistically significant, increase in ruminal volume was observed following feeding. The effects of diet on volume and liquid dilution rate of the rumen must be considered when assessing total nutrients available for animal absorption.     

Volatile fatty acids in the rumen of sheep fed a synthetic diet

A trial was conducted with wethers to study the effect of the administration of a synthetic diet (composition: 30.125% starch, 30.125% sucrose, 25% cellulose, 5.25% urea, 8.125% mineral supplement, 1.25% maize oil and 0.125% cholinechloride) upon rumen fermentation. The adaptation to the synthetic diet lasted three months, the proportion of the synthetic diet increasing every week (by 10%) to the detriment of a traditional diet (composition: 0.5 kg meadow hay, 0.3 kg barley, 0.2 kg wheat bran, salt and straw ad libitum). In the 10th week the animals consumed 0.5 kg granular synthetic diet, 0.2 kg cellulose flakes and 0.01 kg polystyrene. After three weeks of the administration of the fully synthetic diet, the rumen fluid was sampled after morning feeding in intervals of 0, 1, 3, 5 and 7 hours. In the dynamics of fermentation, statistically significant differences were found only in isobutyric and isovaleric acid between the 0th and 1st and between the 5th and 7th hours (P less than 0.05--P less than 0.001). The data for all the time intervals were recalculated to average values. These were as follows: total volatile fatty acids 63.03 mmol/l, acetic acid 51.00 mol%, propionic acid 26.75 mol%, butyric acid 19.43 mol%, isobutyric acid 0.91 mol%, isovaleric 1.27 mol%, valeric acid 0.62 mol%, energy efficiency of VFA production 78.23%. The obtained data are confronted with literary data on synthetic diets which contained urea and various energy sources.     

Effects of general anesthesia on myoelectric activity of the intestine in horses.

Myoelectric activity was monitored from the terminal ileum, cecum, and colonic pelvic flexure by use of AgpAgCl bipolar electrodes in 4 adult horses before, during, and after general anesthesia. Horses were anesthetized by way of 3 commonly used regimens, including xylazine (1.1 mg/kg of body weight) and ketamine hydrochloride (2.2 mg/kg); thiopental sodium (7.7 mg/kg), followed by halothane vaporized in oxygen; and thiopental sodium (2.5 g) in guaifenesin (100 mg/ml) solution given to effect, followed by halothane in oxygen. All 3 anesthetic regimens decreased intestinal spike-burst activity in the areas monitored. The slowest return to preanesthetic myoelectric activity was observed after xylazine and ketamine administration. After both of the barbiturate/halothane anesthetic regimens, there was a rebound increase in spike-burst frequency, without alteration in the proportion of propagative myoelectric events. All 3 anesthetic regimens appeared to reset the timing of the small and large intestinal migrating myoelectric complexes. By 9 hours after recovery from anesthesia, the effects of anesthesia, irrespective of regimen, had disappeared. Although anesthesia significantly (P less than 0.05) altered intestinal myoelectric activity, no particular anesthetic regimen had a prolonged effect. Results of our study indicate that the particular chosen regimen of general anesthesia is unimportant in development of motility disturbances in horses after anesthesia.     

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.     

丙二醇对围产期奶牛日粮养分消化率的影响

选用24头体重(683.1±14.9)kg、胎次(2.5±0.2)、上一泌乳期305 d,产奶量(7 339±18)kg和预产期(24.5±0.2)d的经产奶牛,随机分为4组,从分娩前19 d到分娩后36 d分别在基础日粮中添加丙二醇0、150、300和450 ml/d,研究丙二醇对围产期奶牛采食量和日粮养分消化率的影响,结果表明:奶牛分娩后7、21和35 d干物质(DM)、有机物质(OM)、粗蛋白质(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)采食量显著高于分娩前(-21 d和-14 d),分娩后35 d各养分采食量显著高于分娩后7 d(P<0.05)。从分娩前14 d到分娩后35 d各组奶牛DM、OM和CP消化率呈先降低后升高的趋势,但差异均不显著;而分娩后7、21和35 d日粮NDF和ADF消化率显著低于分娩前(-21 d和-14d)(P<0.05)。日粮添加不同水平的丙二醇对围产期奶牛各养分采食量均无显著影响(P>0.05)。与对照组相比,日粮添加丙二醇300 ml/d和450 ml/d,显著提高分娩前14 d和分娩后7、21和35 d DM、NDF和ADF消化率,显著提高分娩后7、21和35 d OM消化率,显著提高分娩后7和21 d CP消化率(P<0.05)。本试验结果表明在日粮中添加丙二醇有益于改善围产期奶牛日粮消化率,适宜添加量为300 ml/d。     

异麦芽糖对泌乳早期奶牛瘤胃发酵及生产性能的影响

为了研究异麦芽糖对泌乳早期奶牛瘤胃发酵及生产性能的影响,选择4头泌乳天数为20 d、日产奶量30 kg左右、体重550 kg左右的经产(二胎)中国荷斯坦泌乳奶牛,随机分为2组,对照组饲喂基础日粮,试验组在基础日粮中添加60 g异麦芽糖,采用2×2交叉试验设计,每期21d。结果表明:添加异麦芽糖可以显著提高奶牛瘤胃中挥发性脂肪酸(VFA)的含量(P0.05),显著降低氨态氮(NH_3-N)的含量(P0.05),其中瘤胃液中丁酸含量有极显著差异(P0.01),乙酸和丙酸的含量呈上升趋势,但无显著差异(P0.05)。对奶样进行分析,添加异麦芽糖可以显著提高牛奶的乳脂率(P0.05),显著降低乳体细胞数(P0.05),产奶量、乳蛋白和尿素氮浓度均无显著差异(P0.05)。综上所述,异麦芽糖有助于改善奶牛的瘤胃发酵功能,提高牛奶的乳脂率。     

Effects of fat coated rumen bypass lysine and methionine on performance of dairy cows fed a diet deficient in lysine and methionine

Two experiments were conducted to evaluate the effect of fat coated rumen bypass lysine (RPLys) and methionine (RPMet) on the lactation performance of dairy cows. In Experiment 1, three lactating cows were supplied with RPLys and fat coated DL‐Met which was highly protected (H‐RPMet) as an indigestible marker, and total fecal emission was collected for 72 h following administration. Measuring the proportional difference in fecal excretion of lysine derived from RPLys relative to methionine derived from H‐RPMet, the intestinal availability of RPLys was estimated to be 66.2%. In Experiment 2, 20 multiparous Holstein cows producing approximately 40 kg/day of milk were assigned to two treatments; fed RPLys (16 g/day as lysine) and RPMet (6.5 g/day as methionine) or none (control) from 5 to 21 weeks postpartum. The consumption of dry matter, organic matter, crude protein, neutral detergent fiber and acid detergent fiber were significantly more in the control cows throughout the experimental period. Their milk protein yield, the contents of their milk protein and milk fat were higher by 0.03 kg (P = 0.03), 0.06% (P < 0.001) and 0.11% (P = 0.07), respectively, in the treatment group compared to the control. These results suggest that the RPLys and RPMet used in this study improved the lactation performance of dairy cows.     

Effect of the roughage sequence and concentrates in animal feed on carbohydrate digestion and bacterial protein synthesis in the rumen of dairy cows

In experiments with dairy cows provided with rumen fistulas and duodenal re-entrant canulas, the order of feeding roughage (chopped forage and pellets) and concentrates (maize and barley) was found to influence carbohydrate digestion and bacterial protein synthesis in the rumen. Feeding the roughage 90 min. before the concentrate caused a wider C2:C3 ratio and a sustained course of the pH-value (greater than 6.5) than the ratio other way round. This favoured cellulose digestion in the rumen when feeding chopped roughage. When feeding roughage before concentrates, the nonbacterial N-proportion in the duodenal contents proved greater than in the reverse order and revealed the highest values for roughage fed in pelleted form. Feeding structured roughage as first component of the diet with concentrates given afterwards is, therefore, recommended for dairy cows.