Influence of dietary niacin on volatile fatty acids in rumen liquid of sheep and rumen dry matter degradability of untreated and ammonia-treated wheat straw

Three rumen fistulated sheep were fed with roughage (1200 g artificially dried grass) or a concentrate/roughage diet (600 g concentrate, 400 g artificially dried grass per animal and day). The diets were unsupplemented or 0.5, 1 and 2 g niacin per animal and day were added. After a 14-day adaptation period samples of rumen liquid were taken 0, 1, 2, 3, 4 and 6 h after morning feeding. In a second experiment untreated and NH3-treated wheat straw were incubated in nylon bags for 6, 12, 24, 48 and 72 h in the rumen of 5 sheep fed with 1.2 kg artificially dried grass and unsupplemented or supplemented with 1 g niacin per day. Niacin did not significantly influence the total concentration of volatile fatty acids, acetate and branched chain fatty acids in both types of diet (P less than 0.05). 0.5 and 1 g niacin in the roughage and 0.5 g niacin in concentrate/roughage diet increased the propionic acid concentration and reduced the butyric acid concentration in rumen liquid of sheep (P less than 0.05). Niacin resulted in a small decrease (P greater than 0.05) of dry matter degradability in rumen. After 48 h incubation time, the dry matter disappearance of untreated and NH3-treated wheat straw amounted to 35.4 and 46.2% resp. The effects of niacin on rumen fermentation may be useful in avoiding ketogenic situations in dairy cows.     

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.     

Profile of isoacids in rumen fluid and influence of added isoacids on in sacco dry matter disappearance of untreated and ammonia treated wheat straw

The influence of type of diet and time after feeding on concentration of isoacids in rumen fluid of 6 fistulated sheep were investigated. The concentration of isoacids in rumen fluid was higher in diets rich in concentrate and protein (5.6) than in roughage diets (3.4) or in straw-starch-urea diets poor in native protein (highest concentration: 2.1 mmol/l rumen fluid). Feeding of roughage diet or straw-starch-urea-diet effected a significant decrease of concentration of isoacids in the rumen fluid after morning feeding, but concentrate-roughage diet, increased the isoacids-concentration. Reasons for decreased concentration of isoacids may be a shortage of corresponding amino acids and a high activity of cellulolytic microbes. Infusion of isoacids (3 g per day) in the rumen of sheep fed with a straw-starch-sugar-urea diet did not significantly influence the in sacco dry matter degradability of untreated wheat straw, but increased the dry matter loss of ammonia treated wheat straw from 16.0; 26.6; 39.4; 54.0 and 58.8% to 17.3; 29.7; 43.1; 56.3 and 63.0% after 6; 12; 24; 48 and 72 h rumen incubation time respectively. Further experiments seem to be necessary. The effect of isoacids may be expected to occur with poor quality feeds, rich in fibre low in protein and hence low in branched-chain amino acids.     

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.     

Decreasing the roughage:concentrate ratio of a diet to determine the critical roughage part for beef cattle.

The critical roughage part (CRP) of 2 diet types was determined in a cross-over design with 6 double-muscled and 6 normally conformed Belgian Blue bulls fitted with rumen cannulae. The roughage:concentrate ratio was lowered weekly until signs of a lack of physical structure were observed. For diet 1, consisting of maize silage and concentrates, the initial proportion of maize silage was 25% of DM but it decreased weekly with 5% units of DM. For the second diet, consisting of wheat straw and concentrate, 12% straw (DM basis) was provided during the first week and thereafter the proportion of straw decreased weekly with 3% units of DM. Several directly observable parameters (rumen pH, feed intake, bloat, faecal consistency) were evaluated weekly for each bull. Apart from these direct indicators of acidosis, also other parameters, whose results were only available after the end of the trial, were determined (volatile fatty acid profile, lactic acid concentration, chewing time). The roughage part between the part fed when signs of a lack of physical structure was first observed and the part that was fed the week before, was considered as the CRP. Most animals showed no acute signs of clinical acidosis (directly observable parameters) and finished the trial on a 100% concentrate diet. However, in sacco rumen DM-degradabilities of maize silage, grass silage and wheat grain was depressed considerably when low roughage diets were fed. Based on all observed parameters, the mean CRP was calculated to be 14.7% for diet 1 and 8.1% for diet 2. The beef type (double-muscled or not) had no influence on the CRP.     

Effects of ruminal dosing of mechanical stimulating brush on digestibility and rumen fermentation status in Holstein steers fed low rice straw at different lengths

The objectives of the present study were to determine the effect of ruminal dosing of mechanical stimulating brush (Rumen faibu; RF) on digestibility and on rumen fermentation status in Holstein steers fed high concentrate and low rice straw. Eight steers (461 kg in average bodyweight) were used. Four steers were orally dosed three RF per head (RF‐dosing) and the other four were not dosed (non‐RF). All steers were fed enough concentrate and rice straw to gain 1.4 kg/day in bodyweight. Rice straw was cut 2 cm and 30 cm. The organic cell wall content of feeding diets was 17% in dry matter basis. Digestibility and nutritive value were not affected by RF dosing and length of rice straw. Ruminal pH was significantly lower in RF‐dosing group than in non‐RF group after feeding, and tended to be higher in long rice straw than in short rice straw throughout the day. There were no clear difference on total volatile fatty acid concentration and molar proportion of volatile fatty acid by RF dosing and length of rice straw throughout examined period. These present results suggest that digestibility and rumen fermentation status are not affected by RF dosing when organic cell wall content of feeding diets is approximately 17% in dry matter with rice straw over 2 cm.     

Effect of supplementation of soy sauce oil and Ca salts of fatty acids on rumen fermentation,milk production and conjugated linoleic acid in milk of dairy cows

Eight cows were used to evaluate the effects of supplementation of soy sauce oil (SO) or Ca salts of fatty acids (FA) on rumen fermentation and milk production. The control diet (CO) consisted mainly of hay, corn silage and a concentrate. In the experimental diets, 400 g/day per cow of SO or FA (soybean oil and rapeseed oil) was supplemented to the CO diet. Experimental period for the three treatments was 14 days, and milk samples were taken during the last 2 days and rumen sample was taken on the last day. Dry matter intake was not affected by the treatments. The number of rumen protozoa at 0 h increased by SO and FA diets. Total volatile fatty acids at 2 h after feeding of SO diet was decreased compared to CO. The milk composition yield did not differ among treatments, although the percentages of fat and protein were decreased by SO and FA diets. The proportions of C8–C16 fatty acids in milk fat decreased, and those of C18 increased by SO and FA diets. The proportion of cis‐9, trans‐11 conjugated linoleic acid in milk fat by SO and FA diets increased by 120% and 135%, respectively. In spite of the slight suppression of rumen fermentation by SO diet, negative effects on feed intake and milk production were not detected.     

不同加工处理日粮对绵羊瘤胃挥发性脂肪酸的影响

选用3只健康并安装永久性瘤胃瘘管的杂种羯羊,平均体重为24 kg,采用3×3无重复拉丁方试验设计,用3种不同日粮(全混合颗粒料日粮、粉碎精料+铡短粗料日粮和未粉碎精料+铡短粗料日粮)来研究对绵羊瘤胃挥发性脂肪酸(VFA)浓度的影响。结果表明,采食未粉碎精料+铡短粗料日粮绵羊的瘤胃总挥发性脂肪酸(TVFA)浓度显著高于采食全混合颗粒料日粮绵羊(P＜0.05),采食未粉碎精料+铡短粗料及粉碎精料+铡短粗料日粮的绵羊瘤胃丙酸摩尔比显著或极显著高于采食全混合颗粒料日粮绵羊(P＜0.05,P＜0.01),而(戊酸+异戊酸)摩尔比极显著低于全混合颗粒料日粮绵羊(P＜0.01),乙酸/丙酸显著或极显著低于采食全混合颗粒料日粮绵羊(P＜0.05,P＜0.01)。因此,用粉碎精料+铡短粗料或未粉碎精料+铡短粗料日粮饲喂绵羊能改善绵羊瘤胃发酵类型。     

不同精粗比日粮对奶山羊瘤胃液pH值、VFA及血液VFA含量的影响

本试验旨在探讨不同精粗比日粮对奶山羊瘤胃液pH值、VFA以及血液中VFA含量的影响。选择8只安装永久性瘤胃瘘管的奶山羊作为试验动物,采用完全随机分组试验设计随机分为2组,分别饲喂精粗比为6∶4和4∶6的日粮,预饲期15 d,采样期3 d。结果表明,高精料组(HC组)瘤胃液pH值显著低于低精料组(HR组)(P<0.05);在采食后3 h,HC组与HR组瘤胃液pH值均下降至最低值,分别为5.71和6.08。除了乙酸含量外,HC组瘤胃液丙酸、异丁酸、丁酸、异戊酸、戊酸以及总挥发性脂肪酸(TVFA)含量分别比HR组提高4.99%、5.58%、21.81%、17.95%、18.27%、1.66%。HC组血浆中各种VFA的含量均高于HR组,其中丙酸、丁酸含量两组间差异达到显著水平(P<0.05)。HC组瘤胃液以及血浆中乙酸与丙酸比值均低于HR组,但两组间差异均不显著(P>0.05)。HC组瘤胃液乙酸、丙酸、TVFA浓度在采食后2 h达到最大值,HR组在采食后3 h达到最大值,两组日粮血浆中VFA浓度均在采食后2 h达到最大值,然后逐渐恢复到采食前水平。结论:高精料日粮导致瘤胃液pH值显著降低,瘤胃液和血浆中VFA含量增加;瘤胃液VFA生成速率HC组高于HR组。     

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.     

Effect of feeding regime on the metabolism of ochratoxin A during the in vitro incubation in buffered rumen fluid from cows.

Pure ochratoxin A (OA) was added to buffered rumen fluid collected from two fistulated cows and incubated under anaerobic conditions. Both animals were fed six diets containing grass, grass silage or hay, and two different amounts of concentrate consisting of barley and soybean meal. Four incubations per animal and diet were carried out at consecutive days. The concentration of OA declined exponentially to a very low or non-detectable level under all conditions examined, with half-lives at 0.51 to 2.76 h. The disappearance of OA was accompanied by the appearance of ochratoxin alpha (O alpha) with an average amount of O alpha formed relative to the disappearance of OA near 100%, independent of diet and animal. Based on four incubations per animal and diet the rate of OA disappearance was affected (P < 0.1) by the origin of rumen fluid from two animals, as well as by the type of basic component and amount of concentrate in the diet, with interactions between these factors. The disappearance of OA mostly was accelerated (P < 0.1) by replacing grass silage or hay by fresh grass and by increasing the content of concentrate from 10 to 50% of dry matter. It is concluded that the capacity of the rumen to detoxify OA is not limited by the yield of Oa from OA but is strongly dependent on animal and diet.     

Investigations on the effects of Ca-soap of linseed oil on rumen fermentation in sheep and on milk composition of goats

Six rumen-cannulated wethers were fed by a diet composed of alfalfa hay and concentrate and supplemented by 75 g Ca-soap of linseed oil (5.4% in dry matter, DM) daily. A model trial was performed to detect the effects of the Ca-soap on rumen fermentation parameters and on fibre digestion. Approximately 3 h after feeding Ca-soap, ratio of C2:C3 decreased (from 4.33 to 4.02) and the production of i- and n-butyrate and i- and n-valeriate increased by 28, 5.3, 11.76% and 6.80% respectively. Total volatile fatty acid concentration in rumen fluid did not change (126.1 vs. 126.4 mm) as a result of Ca-soap supplementation. The in vitro trial showed no detrimental influence of Ca-soap on the acid detergent fibre (ADF) degradation. Using feed samples containing Ca-soap to be incubated in tubes, ADF digestion proved to be significantly higher (p < 0.001). Approximately 14 goats (Saanen breed, 30-70 days in lactation) were used to test the effects of Ca-soap on milk composition. Their ration contained alfalfa hay, millet straw and a concentrate. In the experimental group (seven goats) the diet was supplemented with Ca-soap of linseed oil (75 g/animal/day). The milk composition was changed (slightly reduced solid content, sometimes significantly reduced milk fat contents), when Ca-soap was included in the diet of lactating goats.     

The effect of monensin on rumen fermentation and weight gain in bulls fed a diet containing nontraditional feed

Two groups of bullocks, each consisting of 125 animals, were subjected to a trial to study the effect of monensin (Rumensin premix) administered at doses from 125 to 175 mg per head/day on rumen fermentation and weight gains. For 135 days the animals were given a diet based on green juicy forage with a supplement of chopped straw and concentrate mixture; this mixture contained 20-30% of dried poultry droppings. In the experimental group with monensin, the concentration of total and protein nitrogen and the molar percentage of propionic acid significantly increased (23.7 and 28.5%, respectively, P less than 0.01) and the acetate: propionate ratio decreased four hours after feeding. Further, the energy yield of the production by volatile fatty acids (VFA) significantly increased in the rumen contents (76.89%, 78.64%, respectively, P less than 0.05). The levels of ammonia and non-protein nitrogen were not affected by the addition of monensin. The average daily live weight gains were 713 g in the control group and 800 g in the experimental group; this means that the gains of the experimental animals rose by 12.2%. Monensin had a positive influence on the proportions of the rumen-produced VFA in favour of propionic acid which, in turn, favourably influenced the energy balance of nutrient conversion and efficiency.     

Characteristics of water soluble markers for measuring rumen liquid volume and dilution rate

The utility of five water soluble markers (WSM) for measuring rumen liquid volume and dilution rate was examined in nine in vitro and in vivo experiments. The WSM tested included polyethylene glycol (PEG) and ethylenediaminetetraacetic acid (EDTA) complexes of Cr, Co, Fe and Yb. Feedstuffs incubated in vitro absorbed variable amounts of distilled H2O and autoclaved rumen fluid with roughages imbibing greater (P less than .05) amounts of fluid than feeds higher in starch. Liquid present in the feeds tested reached equilibrium with added WSM in about 20 min. Corn grain in the whole or ground form appeared to exclude 4 to 16% of the WSM while imbibing water. Cottonseed hulls reduced detectable PEG due to some water soluble substance present. The WSM tested did not produce different estimates of dilution rate (P = .65) and volume (p = .29) of steers fed either 80% whole shelled corn, 90% chopped alfalfa hay or 90% prairie hay diets. Ruminal liquid measured by hand removal was about 4% greater than volume estimated by WSM. The percentage of total ruminal water associated with solids varied from 27 to 86% among steers. Compared with steers fed an 80% whole shelled corn diet, steers fed equal dry matter from alfalfa hay had 15% more dry matter in the rumen, 21% larger liquid volume, 80% greater ruminal liquid dilution rate and 116% greater rate of liquid flow from the rumen. Dilution rate of ruminal liquid during feeding was examined with six steers fed a 90% chopped alfalfa hay diet once daily at 1.8% of body weight. Dilution rate estimated with Co EDTA increased by 166% during the 4 h after feeding. The WSM did not influence (P greater than .10) digestibility of dry matter with steers fed a 90% roughage or a 90% concentrate ration. Recovery of WSM administered via a rumen cannula ranged from 96.8 to 99.7% in feces and 1.2 to 3.4% in urine. All WSM examined appeared suitable for estimating rumen liquid volume and dilution rate for diets not containing cottonseed hulls.     

Effect of the last diet on the selective feeding behavior of heifers

The present study examined and discussed the way the basal diet (BD) during the preliminary phase and the last diet (LD) before the food selection test affected the selective feeding behavior of heifers. For the BD and LD, oat hay and concentrate were used. Three different levels of roughage content (low, medium and high) were prepared by changing the mix ratios of oat hay and concentrate. Low and high roughage diets were used for the BD, and all three of the roughage levels were used for the LD. A mixture of orchard grass and white clover (MIX), and Japanese pampas grass leaf (JP) were used as testing foods. In the preliminary phase, all heifers were fed the BD three times per day. In the test phase, heifers were fed the LD for the first meal (06.00–12.00 hours), and food selection under different BD and LD was examined during the second meal (13.00–16.00 hours) of the day. The effects of the BD were significant for MIX dry matter intake (DMI), JP DMI and the rate of MIX DMI for total DMI. Under the high roughage BD condition, heifers ingested more MIX than under the low roughage BD condition. The effect of the LD was significant on JP DMI, whereas the rate of MIX DMI for total DMI was not significant. Selective feeding behavior was strongly affected by the BD and slightly by the LD.     

Effect of monensin on rumen ciliate protozoa in sheep

In a first experiment 4 rams consumed over a period of 70 days 0; 82; 208 and 345 mg of monensin daily, respectively. All doses of monensin caused a marked decrease in total numbers of rumen protozoa in samples taken after this period. More than 90% of total protozoal numbers belonged to the genus Entodinium. The sensitivity of the genus Entodinium to monensin was found to be lower than that of genera Dasytricha and Isotricha. In the second experiment 24 lambs were fed hay and concentrates in the ratio 60:40% (groups 1 and 2) and 40:60% (groups 3 and 4). Groups 2 and 4 received 40 mg monensin per animal daily during 16 weeks. The decrease in protozoal numbers due to monensin in samples taken after this period was significant (P less than 0.001) in lambs fed the concentrate diet (groups 3 and 4) and also in lambs from groups 1 and 2 fed the roughage diet (P less than 0.05). The statistical evaluation of the inhibition of total protozoal numbers by monensin (%) in lambs fed both diets has shown that the antiprotozoal effect of monensin was significantly more intensive with the concentrate diet (P less than 0.025) than with the roughage diet.     

Nutrient intake of horses in Thoroughbred and Standardbred stables

SUMMARY Twenty-five Thoroughbred (TB) and 25 Standardbred (SB) stables were visited to determine their feeding practices. The ingredients of the main feed of the day for a mature gelding of average size in full training were weighed at each stable. Nutrient content of diets was calculated using published data for the individual ingredients. Results are expressed as mean±sd. The estimated body weight of TB horses was 493±34 kg and 437±32 kg for SB horses. There was considerable variation in diet composition and nutrient intake between stables. The TB trainers fed 11.0±2.4 kg and SB trainers 11.8±2.5 kg per day. The concentrate component of the diet weighed 7.8±1.6 and 7.7±2.3 kg for TB and SB stables, respectively, and the roughage component for TB horses 3.3±1.4 and SB horses 4.1±1.4 kg per day. The digestible energy intake of horses at TB stables was 129±29 MJ per day and at SB stables 132±31 MJ per day. Crude protein intake of TB horses was 1452±363 g and SB horses 1442±338 g per day. There were differences in some feeding practices at TB and SB stables. Standardbred trainers fed more roughage than TB trainers. Standardbred trainers fed chaffed lucerne (alfalfa) and cereal hays as the major roughage, whereas TB trainers fed more hay. The major hay type fed by TB trainers was lucerne, whereas many SB trainers preferred clover hay. Both trainers fed oats as the major grain, but TB trainers fed slightly more maize (corn) than SB trainers. The SB trainers fed barley as part of the concentrate component of the diet, whereas TB trainers usually fed boiled barley and linseed oil in winter only. Although many trainers used vitamin and mineral supplements, this appeared unnecessary in many Instances, especially with respect to Iron. Calcium and NaCI supplementation was necessary for some diets. We concluded that while there was a wide range in feed intake and diet composition for both TB and SB horses, average nutrient intakes were similar to National Research Council (1989) recommendations for horses performing intense work.     

The effect of lasalocid on apparent digestibility, characteristics of rumen fermentation and fattening and slaughter output of bulls

Four digestion experiments with 5 wethers each (Feeding: artificially dried grass; 0, 15, 30 or 60 mg lasalocid per animal and day), two short time experiments (Exp. 1: 3 rumen fistulated sheep; feeding; artificially dried grass; 0, 15, 30 or 60 mg lasalocid per animal and day; exp. 2: 20 bulls; feeding; 2 kg concentrates per animal and day; wheat straw ad libitum; 0, 150 or 300 mg lasalocid per animal and day) and one individual feeding experiment (24 bulls per group; duration: 279 days, feeding: 2 kg concentrates per animal and day, corn silage and whole barley-grass silage ad libitum; 0 or 100/200 mg lasalocid per animal and day) were carried out in order to investigate the influence of the ionophore lasalocid on digestibility, figures of rumen fermentation as well as fattening and slaughtering results of bulls. Higher doses of lasalocid (30 and 60 mg per animal and day) decreased significantly digestibility of organic matter (1.8 and 2.8 units) and crude fibre (5.8 and 7.2 units). Relative acetate (22 to 120 mmoles per mol) and butyrate concentration (23 to 58 mmoles per mol) were decreased and molar propionate concentration of rumen liquid (25 to 154 mmoles per mol) was increased depending on level of lasalocid supplementation. Lasalocid did not significantly influence the dry matter intake; daily weight gain and slaughtering results were increased (4.4 and 6.1%), energy efficiency was improved (3.8%). Effects of lasalocid are similar to that of monensin. A dose of 20 to 30 mg lasalocid per kg dry matter is recommended.     

饲粮中燕麦干草含量对绵羊瘤胃液pH及微生物区系的影响

本试验旨在研究饲粮燕麦干草含量对绵羊瘤胃液p H及微生物区系的影响。选取9只体况和体重[(70.32±2.14)kg]相近、装有永久性瘘管的德国美利奴与蒙古羊杂种公羊,采用3×3拉丁方设计,随机分为3组,每组3只,各组分别采用全株玉米青贮、全株玉米青贮+燕麦干草(1∶1)(混合组)、燕麦干草为粗饲料。饲粮精粗比34.50∶65.50。进行3期饲养试验,每期20 d,15 d预试期,5 d采样期。采集饲喂前(0 h)和饲喂后1、3、5和7 h的瘤胃液,测定p H,采用实时定量PCR方法测定微生物相对含量。结果表明:1)全株玉米青贮组的瘤胃液p H在1、5 h均显著低于燕麦干草组(P0.05),在3 h极显著低于混合组(P0.01);2)混合组和燕麦干草组瘤胃液真菌的相对含量在0 h均极显著高于全株玉米青贮组(P0.01),燕麦干草组在5 h真菌相对含量显著高于全株玉米青贮组(P0.05);3)混合组原虫的相对含量在1、5 h显著低于全株玉米青贮组(P0.05);4)饲喂后5 h,混合组和燕麦干草组的纤维分解菌相对含量均较高,其中燕麦干草组黄色瘤胃球菌相对含量显著高于全株玉米青贮组(P0.05),白色瘤胃球菌和产琥珀酸丝状杆菌的相对含量极显著高于全株玉米青贮组(P0.01)。综上所述,在精粗比为34.50∶65.50的饲粮中采用全株玉米青贮+燕麦干草(1∶1)的粗饲料,有利于维持绵羊瘤胃内环境的稳态及瘤胃微生物的生长,白色瘤胃球菌和产琥珀酸丝状杆菌为优势菌。     

Selective feeding behavior of calves is affected by basal diet

The present study examined the way the selective feeding behavior of calves was affected by basal diet. Three basal diets containing oat hay and concentrate, with the addition of different levels of roughage content (low, medium and high) were prepared by changing their mix ratios. Orchard grass (OG) and Japanese pampas grass leaf (JP) were used as testing foods. In the preliminary phase, all calves were fed each basal diet three times per day and then food selection between JP and OG was examined. Dry matter intake (DMI) of JP and OG throughout the test was significantly different. Increasing the roughage rate in the basal diet decreased the DMI of JP, whereas the DMI of OG was increased. There was no significant effect of basal diet condition on nutrient intake, whereas the acid detergent fiber and neutral detergent fiber ingestive efficiency were affected by the basal diet condition. It is suggested that calves prefer food that complement the basal diet, even if nutrient requirements are met.