Effects of ruminal infusion of volatile fatty acids on plasma concentration of growth hormone and insulin in sheep.

In an initial experiment we observed postprandial changes in plasma concentrations of growth hormone (GH), insulin, glucagon, and somatostatin (SRIF) in sheep. We then examined whether increasing the rumen concentration of volatile fatty acids (VFA) by infusing a VFA mixture at three rates (53.5, 107, and 214 micromol/kg/min for 4 hr) mimicked the postprandial changes in hormone secretion. Feeding significantly (P < 0.05) suppressed the plasma GH concentration for 6 hr, whereas it significantly (P < 0.05) increased plasma concentrations of insulin, glucagon, and SRIF. Plasma glucose levels tended to decrease after feeding but then gradually increased over the prefeeding level (P < 0.05). Intraruminal infusion of the VFA mixture at 107 micromol/kg/min caused similar changes in ruminal VFA concentrations to those seen after feeding. The infusion significantly (P < 0.05) suppressed GH secretion in a dose-dependent manner, whereas it caused a significant (P < 0.05) increase in insulin and glucose concentrations without changing glucagon concentrations. From these results, we conclude that the postprandial change in ruminal VFA concentration may be a physiological signal which modifies GH and insulin secretion in sheep.     

Effect of ruminal infusion of glucose, volatile fatty acids and hydrochloric acid on mineral metabolism in sheep

Two experiments were conducted to study the effects of alterations in ruminal pH and volatile fatty acid (VFA) concentrations on utilization of Mg and other minerals. In Exp. 1, two metabolism trials were conducted with 12 ruminally cannulated crossbred wethers fed 800 g/d of orchard-grass (Dactylis glomerata, L.) hay. After each feeding, wethers were ruminally infused with 500 ml (4.2 ml/min) or either 1) deionized water, 2) 40% (w/v) glucose solution, 3) .26 M propionic and .17 M butyric acid solution or 4) .35 M HCl. The pH of the VFA solution was adjusted to 6.8 with 10N NaOH. In Exp. 2, a metabolism trial was conducted with 12 ruminally cannulated crossbred wethers fed 600 g of orchard-grass hay and infused with a buffered VFA solution prepared as in Exp. 1 or with an unbuffered solution. In both experiments each trial consisted of a 5-d adaption period followed by four 5-d collections of feed, feces and urine. Compared with the glucose treatment, infusion of the buffered VFA solution produced similar acetic and propionic and higher (P less than .05) butyric acid concentrations (Exp. 1). The HCl solution produced changes in ruminal and pH values similar to those of the glucose infusion. In Exp. 1, apparent absorption of Mg was increased over twofold by the glucose infusion (P less than .05), but the other infusions had no effect. Apparent absorption of P was decreased (P less than .05) by HCl infusion, and K absorption was decreased by HCl and glucose infusions. In Exp. 2, infusion of the unbuffered VFA solution decreased apparent Mg absorption by 15.7%, compared with infusion of the buffered solution. These experiments suggest that the increased Mg absorption observed with carbohydrate supplementation is not due to alterations in ruminal pH or VFA levels.     

The chemical composition of Phyllanthus discoideus and its effect on the ruminal ammonia and volatile fatty acid concentration when fed to west African dwarf sheep.

The feeding value of Phyllanthus discoideus (also called Margaritaria discoidea) leaves was evaluated using eight two-year-old West African Dwarf sheep fed natural grass hay. Four of the animals were fistulated ruminally and used for ammonia and volatile fatty acid determination in the fluid. Dried leaves of Phyllanthus discoideus were offered at two levels (25% and 50% of DMI, diets D25% and D50%, respectively) as supplements to the basal hay diet. The CP content of the control, D25% and D50% diets were 11.5, 12.6 and 13.6%, respectively, and their digestible energy amounted to 58.2, 61.1 and 56.9%, respectively. Rumen liquor was sampled one hour before and one, three and five hours after the morning feeding. Sheep fed the control diet had a higher ruminal ammonia concentration than those fed diet D25%. Similarly, ruminal ammonia concentration was higher in sheep fed the control diet than those fed the diet D50%. Five hours after feeding the ruminal ammonia concentration was significantly lower than one hour after feeding. The VFA concentrations in rumen fluid of sheep fed the control diet was inferior to those fed diets D25% and D50%. Sheep fed diet D50% showed significantly higher VFA concentrations than those fed diet D25%. Digestibility of organic matter and digestible energy did not show any significant difference. However, a marginal increase in organic matter digestibility of 3.5% was observed in diet D25% compared with the control diet. There was no significant difference in the N-digestibility in sheep fed the control, D25% and D50% diets. Nevertheless, a marginal improvement in N-digestibility (1.5%) and N-retention (2.7%) was observed with the highest level of Phyllanthus discoideus (D50%). In conclusion, Phyllanthus discoideus appears as a particularly valuable feedstuff because it contains low levels of condensed tannins (12.8 g/kg), high CP content (156 g/kg) and a relatively high GE content (19.3 kJ/g DM). Although the improvement in N-digestibility and N-retention were only marginal the feeding of Phyllanthus discoideus could be justified under extreme shortage of feed resources during dry season. It should also be mentioned that a much more pronounced effect by supplementation with Phyllanthus discoideus could be expected when poor quality grass hay prevalent in West Africa during the dry season is fed. Phyllanthus discoideus could serve as a supplement to poor quality grass at 25% to 50% of supplementation.     

Effects of fermented Yupingfeng on intramuscular fatty acids and ruminal microbiota in Qingyuan black goats

Our previous work has demonstrated that Yupingfeng, a Chinese herb medicine, considered as prebiotic showed beneficial properties in poultry health and disease prevention and regulated intestinal microbiota. The effects of Yupingfeng on fatty acids related to meat flavor and ruminal microbiota are not yet known in Qingyuan black goat. In this study, we supplemented fermented (FYP) and unfermented (UYP) Yupingfeng in different combinations to 90 goats. Compared with the normal control group, FYP and UYP significantly increased the concentration of palmitic acid, octadecanoic acid, and arachidonate acid (related to meat flavor) in the longissimus dorsi muscle (p < .05). In addition, the significant upregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid translocase (CD36) was observed in the FYP and UYP groups (p < .05). In addition, Firmicutes and Bacteroidetes were the most abundance in goat rumen. At the genus level, FYP and UYP significantly increased Ruminococcus related to fiber degradation, and Alistipes related to short-chain fatty acids production. In summary, Yupingfeng could improve fatty acids of goat meat, which is probably triggered by the increase of PPARγ and CD36, and microbial activity. Besides, FYP showed more beneficial effects than UYP, with increased flavor fatty acids and beneficial microbes.     

利用体外法研究不同水平苜蓿皂苷对山羊瘤胃内pH值和挥发性脂肪酸的影响

试验通过体外培养法研究日粮中添加苜蓿皂苷对山羊瘤胃微生物发酵功能的影响。试验分5组,各组苜蓿皂苷的添加水平分别为基础底物(2g)的0(对照组)、1%、2%、3%及4%,每组3个重复,体外厌氧培养24h,并分别测定各处理组pH值和挥发性脂肪酸含量。结果表明:添加苜蓿皂苷未对培养液pH值产生显著影响;添加1%～4%的苜蓿皂苷可极显著提高培养液中乙酸、丙酸浓度(P<0.01);添加1%的苜蓿皂苷可极显著提高丁酸浓度(P<0.01),2%组可显著提高丁酸浓度(P<0.05);各苜蓿皂苷添加组中乙酸/丙酸的比例均极显著低于对照组(P<0.01)。结论:本试验条件下,添加1%～4%的苜蓿皂苷可改善瘤胃发酵模式,提高反刍动物对发酵终产物的利用率,且添加1%的苜蓿皂苷效果最佳。     

Reduced energy density of close‐up diets decrease ruminal pH and increase concentration of volatile fatty acids postpartum in Holstein cows

The objective of this study was to determine the effect of reduced energy density of close‐up diets on ruminal fermentation parameters in transition cows. Fourteen Holstein dry cows were blocked and assigned randomly to three groups fed a high energy density diet (HD, 1.62 Mcal of net energy for lactation (NE_L)/kg dry matter (DM)), or a middle energy density diet (MD, 1.47 Mcal NE_L/kg DM), or a low energy density diet (LD, 1.30 Mcal NE_L/kg DM) prepartum, and were fed the same diet postpartum. The reduced energy density diets decreased the average dry matter intake (DMI) prepartum and tended to increase the DMI postpartum. The ruminal pH of the LD group was significantly higher prepartum and lower during the first week of lactation compared with the other two groups. The reduced energy density diet depressed the average ruminal concentration of propionate and butyrate prepartum, and increased the average concentration of total volatile fatty acids (VFA) postpartum. The LD group had higher populations of Butyrivibrio fibrisolvens and Ruminococcus flavefaciens relative to HD and MD groups on 7 days in milk. In conclusion, the cows fed reduced energy density diet prepartum had higher VFA concentration, but were more susceptible to subacute ruminal acidosis postpartum.     

A note on the relationship between the production rates of volatile fatty acids and their concentration,digestible organic matter and total digestible nutrient intake in buffalo calves

Volatile fatty acid (VFA) production rates were measured by isotope dilution technique in the rumen of buffalo calves fed on wheat straw plus concentrate, green maize, cow pea and berseem. Correlations derived between the VFA production rates and their concentration and DOM were significant except in animals fed on cow pea. The VFA production rates were also significantly correlated with the TDN intake in all the four feeds tested.The regression equations obtained for the four feeds were different, which suggested that VFA production may vary with the quantity and quality of feed digested. These experiments suggest the use of different regression equations for different feeds.     

Lysozyme concentrations in the tears of cattle, goats, and sheep

Tear samples were collected from 1 eye of each of 40 cows, 27 sheep, 5 goats, and 5 human beings. Additionally, 10 bovine tear samples were pooled and concentrated. Spectrophotometric assays, using Micrococcus lysodeikticus, were performed on each sample to detect lysozyme activity expressed in hen egg lysozyme (HEL) equivalents. Lysozyme activity was not detected in tears of cows, but 158.8 +/- 159.3 mg of HEL/ml was detected in tears of sheep, 220.7 +/- 37.5 mg of HEL/ml in tears of goats, and 216.3 +/- 86.2 mg of HEL/ml in tears of human beings. In pooled bovine tear samples, lysozyme activity was not detected on plate assay and lysozyme protein was not detected on polyacrylamide gel electrophoresis, column chromatography, or immunoelectrophoresis with rabbit anti-bovine tear antibodies. On the basis of these observations, we concluded that the basic ocular protective mechanism in bovine tears is not lysozyme. Other anti-bacterial proteins such as lactoferrin, transferrin, complement, or beta-lysin may, therefore, be of primary importance in protecting the bovine eye.     

Comparison of pepsinogen forms in cattle, sheep and goats

Different types and subtypes of pepsinogen extracted from bovine, ovine and caprine abomasa were found to differ according to their phosphate content and relative molecular mass (Mr). Bovine pepsinogens had organic phosphate contents ranging from 1.65 to 2.22 mol of phosphate mol-1 of pepsinogen. Ovine pepsinogens were in the range 1.50 to 2.36 and caprine pepsinogens were in the range 1.42 to 2.00. The major types of pepsinogen from each species were different in size. Bovine pepsinogen had an Mr of 39,000, ovine had an Mr of 43,000 and caprine pepsinogen had an Mr of 42,000.     

Dynamics of digestion in cattle, sheep, goats and deer

Four experiments were conducted to study factors affecting digestibility of forages in cattle, sheep, goats and white-tailed deer. In a series of digestion trials (Exp. 1), the dry matter digestibility of a moderately high fiber diet was greater in cattle than in deer. Digestibilities of the diet in sheep and goats were intermediate and not different from either extreme. In a second series of trials (Exp. 2), relative organic matter digestibilities were for goats more than sheep more than deer. However, in Exp. 2, intake in goats was very low and digestibility appeared to be positively related to retention time and inversely related to turnover rate. Results of three trials (Exp. 3) suggested that rate of digestion was related more to diet than to the animal species consuming the diet. In grazing animals (Exp. 4), goats digested a smaller percentage of consumed material than either cows or sheep during three of four seasons even though diets were of similar in vitro digestibility. This difference was related to a faster turnover and shorter retention time in goats. These data support the concept that there are species differences in gastrointestinal dynamics which may be which may be important determinants of adaptability to grazing conditions.     

挥发性脂肪酸和乳酸的测定方法研究

乙酸、丙酸、丁酸、戊酸、异戊酸等广泛地存在于自然界中,它们的共同特点是具有较强的挥发性,生物学上一般称之为挥发性脂肪酸(Volatile FattyAcids,VFA)。VFA在动物科学和食品科学上具有十分重要的意义,其代谢和含量是这些研究领域中常遇到的问题。因此,一个好的测定方法是研究中十分必要的。挥发性脂肪酸的测定方法有比色法、滴定法、色谱法等。相比之下,气相色谱法以快速、准确、简便,能分别测定各个组分而适用于多种样品(如:青贮饲料、瘤胃液、血液、饮料等)。但是,气相色谱法也受多种条件的影响,如色谱条件、样品的处理方法等。利…     

挥发性腊肪酸和乳酸的测定方法研究

乙酸、丙酸、丁酸、戊酸、异戊酸等广泛地存在于自然界中．它们的共同特点是具有较强的挥发性．生物学上一般称之为挥发性脂肪酸（Volatile Fatty Acids，VFA）。VFA在动物科学和食品科学上具有十分重要的意义，其代谢和含量是这些研究领域中常遇到的问题。因此，一个好的测定方法是研究中十分必要的．     

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.     

Chiral behaviour of the metabolite albendazole sulphoxide in sheep, goats and cattle

Three sheep, three goats and three cattle were dosed orally with 5.0, 7.5 and 10 mg albendazole kg-1 bodyweight, respectively. Blood samples were taken at intervals for 48 hours after administration. The enantiomeric ratio of the metabolite albendazole sulphoxide (SO.ABZ) was determined by liquid chromatography on chiral stationary phases. At To, the plasma concentration ratio (+)SO.ABZ/(-)SO.ABZ was estimated at 3.0 in sheep, 1.5 in goats and 4.0 in cattle. The proportion of the (+) enantiomer then increased linearly as a function of time during the course of the kinetics. In comparison to the area under the curve for total SO.ABZ, the (+) enantiomer represented 86 per cent in sheep, 80 per cent in goats and 91 per cent in cattle. The specific behaviour of the two enantiomers is probably the result of the enantioselectivity of the flavine adenosine dinucleotide and cytochrome P450 dependent enzymatic systems which are involved in the sulphoxidation and the sulphonation of ABZ.     

Lasalocid and dietary sodium and potassium effects on mineral metabolism, ruminal volatile fatty acids and performance of finishing steers

Thirty Angus steers averaging 357 kg were used to: 1) determine the effect of feeding lasalocid (33 mg/kg diet) on mineral metabolism and 2) determine the effects of varying dietary sodium (Na) and potassium (K) on finishing steers fed lasalocid. Treatments consisted of: 1) control (.25% Na, .5% K); 2) lasalocid (.05% Na, .5% K); 3) lasalocid (.25% Na, .5% K); 4) lasalocid (.05% Na, 1.4% K) and 5) lasalocid (.25% Na, 1.4% K). Ruminal fluid and blood samples were collected on d 28 and 90 of the 102-d study. Gain and feed conversion tended to be higher for steers fed lasalocid with the exception of the .05% Na, 1.4% K treatment. Control steers had lower (P less than .05) erythrocyte K concentrations, reduced (P less than .05) soluble concentrations of magnesium and copper in ruminal fluid and decreased plasma concentrations of zinc (P less than .05) and phosphorus (P less than .10) at 90 d compared with steers fed lasalocid and similar concentrations of Na (.25%) and K (.5%). Increasing dietary Na from .05 to .25% in the presence of lasalocid increased (P less than (P less than .05) molar proportion of ruminal acetate at 28 and 90 d reduced (P less than .05) propionate at 90 d. Increasing K from .5 to 1.4% decreased (P less than .01) soluble Na and increased (P less than .01) soluble K concentrations in ruminal fluid. Steers fed lasalocid (.25% Na, .5% K) had lower concentrations of K (P less than .10) and zinc (P less than .10) in liver than control steers. Sodium and K level also affected tissue concentrations of certain minerals. Results suggest that dietary Na and K influence mineral metabolism and that dietary Na affects ruminal molar proportion of acetate in cattle fed lasalocid.