Effect of arachis oil on the conservation of heavily wilted herbage ensiled in plastic containers. I. Effect on silage fermentation quality, nutritive value, nutrient losses and intake by sheep

Arachis oil was added to heavily wilted herbage of approximately 40% dry matter, before ensiling in polyethylene containers. The oil was added at a mean level of 4·16% of the total dry matter ensiled. The mean dry matter loss from the two control and the two oil-treated silages teas approximately 13%. There was a lower loss as inedible waste in the oil-treated silages and mould growth appeared to be inhibited by the oil. There was a lower percentage of butyric acid and propioiuc acid in the oil-treated silages than in the control silages, this effect being statistically significant. Ensiling resulted in a greater fall in digestibility of the control material than in the oil-treated material. The oil-treated silages had higher metabolisable energy contents than the control silages but the dry matter intakes of both silages by sheep were low.     

Conservation of wilted herbage ensiled in sealed plastic containers,with and without the addition of urea,and its intake by sheep

Timothy-meadow fescue grass was wilted to 27.7–33.9% dry matter content and two silos were filled with the wilted material alone and two with the wilted herbage to which urea, at a level of 1.38% of the dry matter ensiled, was added. The mean dry matter loss from the control silages was 16.7% and from the urea-treated silages 11.4%. No urea could be detected in the silage made from the urea-treated herbage. There was no evidence for any major differences in the fermentation pathways between the control and urea-treated silage. Voluntary intake of control and urea-treated silage by sheep was similar (1.7 times the maintenance metabolisable energy requirement) so that nitrogen intake was higher when the urea-silage was fed. No toxic effects of the treated silage were observed when assessed by blood urea and ammonia levels.     

Conservation of wilted and unwilted grass ensiled in air-tight metal containers with and without the addition of molasses

Italian ryegrass was ensiled in gas-tight silos in unwilted (21% dry matter) and wilted (42% dry matter) conditions without an additive and with the addition of molasses at a mean level of 8% in the dry matter. The total dry matter losses were 8·7, 7·2, 4·5 and 5·0% for unwilted, molassed unwilted, wilted, and molassed wilted grass silages respectively. The silages were all well preserved but the extent of fermentation had been reduced in the wilted silages. The losses of individual sugars during the silage process and the products of fermentation were used to assess the pathways of fermentation. The dominant pathway of fructose utilisation was by heterolactic fermentation. The addition of molasses reduced the ratio of fructose: glucose in the ensiled material and reduced the amount of mannitol produced during the ensilage process.     

Effect of calcium salts of fatty acids on rumen function and the digestibility of rations by sheep

Experiments were conducted to determine the effects of supplementing chopped ryegrass hay with 0, 1.5, 3, 6 or 12% calcium salts of fatty acids (CaSFA; Megalac) on digestion in the rumen of cannulated cows and on nutrient digestibility by sheep. In-situ ruminal disappearances of dry matter (DM) and cell wall fractions (acid detergent fibre, ADF, and neutral detergent fibre, NDF) were measured by the nylon bag technique. The DM, ADF and NDF disappearances were reduced for diets containing CaSFA at the 1.5, 3 or 6% levels after 48 h of rumen exposure. For diets containing 12% CaSFA, irrespective of the time of rumen incubation, DM disappearance was decreased, while ADF and NDF breakdown was improved. CaSFA supplementation did not influence invitro fermentation characteristics (pH, volatile fatty acid patterns). A digestibility experiment with six mature sheep showed no difference in nitrogen digestibility between unsupplemented and CaSFA-supplemented diets. However, digestibilities of DM, ADF and NDF were higher relative to the basal for the 12% CaSFA: 63.1 versus 60.6%, 63.8 versus 58.7% and 67.4 versus 62.7%, respectively. Ether extract digestion was enhanced by increasing the level of CaSFA, the corresponding values being 49.1, 66.5, 78.6, 81.9 and 77.9% at 0, 1.5, 3, 6 and 12% CaSFA, respectively. Apparent digestibility of energy was higher for the 12% CaSFA than the control diet 68.8 versus 62.1%). Nitrogen and energy retention was improved due to the decreases in urine and faecal excretion, respectively.     

Effect of carbon-4 and carbon-5 volatile fatty acids on growth of mixed rumen bacteria in vitro

Mixed ruminal bacteria (400 mg cells/liter) were incubated in artificial media containing ammonia, sodium carbonate, macrominerals, vitamins, sulfide, microminerals, acetate, propionate, and butyrate. When mixed carbohydrates (equal parts glucose, maltose, sucrose, cellobiose, and soluble starch) were added at 155 mg/liter per h for 10 h, average bacterial growth rate was slow, and dry weight yield was greater than 23%. Additions of isobutyrate, valerate, isovalerate, and 2 methylbutyrate had little influence on synthesis of bacterial dry weight, deoxyribonucleic acid, ribonucleic acid, or carbohydrate. When a timothy hay inoculum was used, isovalerate and 2 methyl-butyrate increased protein synthesis by 11.2 and 16.4%, but isobutyrate and valerate alone were without effect. All four acids combined increased bacterial protein by 18.7%. Responses with an inoculum of 60% concentrate and mixed hay were smaller and not statistically different from control incubations. Low concentrations of Trypticase (less than 250 mg/liter) improved efficiency of microbial protein synthesis from organic matter, but more was associated with decreased efficiency and utilization of extracellular ammonia.     

Form of calf diet and the rumen. II: Impact on volatile fatty acid absorption

Diet is known to affect rumen growth and development. Calves fed an all-liquid diet have smaller and less developed rumens and a decreased ability to absorb volatile fatty acids (VFA) compared to calves fed both liquid and dry feed. However, it is unknown how rumens respond when challenged with a defined concentration of VFA. The objective of this study was to assess the effects of 2 different feeding programs on VFA absorption in preweaned calves. Neonatal Holstein bull calves were individually housed and randomly assigned to 1 of 2 diets. The diets were milk replacer only (MRO; n = 5) or milk replacer with starter (MRS; n = 6). Diets were isoenergetic (3.87 ± 0.06 Mcal of metabolizable energy per day) and isonitrogenous (0.17 ± 0.003 kg/d of apparent digestible protein). Milk replacer was 22% crude protein, 21.5% fat (dry matter basis). The textured calf starter was 21.5% crude protein (dry matter basis). Feed and ad libitum water intakes were recorded daily. Calves were exposed to a defined concentration of VFA buffer (acetate 143 mM, propionate 100 mM, butyrate 40.5 mM) 6 h before euthanasia on d 43 ± 1. Rumen fluid samples were obtained every 15 to 30 min for 6 h to measure the rate of VFA absorption. Rumen tissues were obtained from the ventral sac region and processed for morphological and immunohistochemical analyses of the VFA transporters monocarboxylate transporter 1 (MCT1) and 4 (MCT4). Body growth did not differ between diets, but empty reticulorumens were heavier in MRS than MRO calves (0.67 vs. 0.39 ± 0.04 kg) and MRS calves had larger papillae areas (0.76 vs. 15 ± 0.08 mm²). We observed no differences between diets in terms of the abundance of MCT1 and MCT4 per unit area. These results indicate that the extrapolated increase in total abundance of MCT1 or MCT4 in MRS calves was not due to increased transporter density per unit area. Modeled VFA absorption metrics (flux, mmol/h, or 6 h absorbed VFA in mmol) were not different across diets. These results demonstrate that the form of calfhood diet, whether solely MR or MR and starter, does not alter VFA absorption capacity when the rumen is exposed to a defined concentration of VFA at 6 wk of age.     

Influence of methionine hydroxy analog and DL-methionine on rumen protozoa and volatile fatty acids

Three lactating Holstein cows with rumen cannulae were used in a 3 X 3 Latin square arrangement of treatments to study effects of methionine source on ciliated protozoa numbers and volatile fatty acid concentrations in the rumen. Cows were fed total mixed diets twice daily of 60% grain mix, 21% corn silage, and 19% alfalfa hay (dry basis). Methionine hydroxy analog, DL-methione, and sodium sulfate were added on an equal sulfur basis. Experimental periods were 14 d with four rumen samples taken daily on d 13 and 14. Total ciliated protozoa were higher when cows were fed DL-methionine than when fed methionine hydroxy analog or sodium sulfate. Ruminal concentrations of butyric acid and isobutyric acid were higher for the DL-methionine treatment than for analog or sodium sulfate treatments. Isovaleric acid concentrations were also higher in fluid from cows fed methionine compared with cows fed the analog.     

The effect of formalin and lower volatile fatty acids on silage fermentation

Lolium multiflorum was ensiled in 3 kg capacity PVC silos after treatment with formalin, formic acid, acetic acid and propionic acid applied singly and in mixtures of two, three and four at a constant application rate of 4.5 g kg^?1 fresh grass. The extent of fermentation was assessed by measuring pH, WSC, VN and TSN, and by microbiological analysis of total microorganisms and yeasts. The stability of the silages on exposure to air was measured using a specially constructed temperature recording apparatus. All additives restricted fermentation, although acetic acid and propionic acid were less effective than formalin, formic acid and mixtures of additives. The most aerobically stable silages were those treated with propionic acid, formic/acetic acids, and formic/acetic/propionic acids.     

Effect of free fatty acids on the flavour of frying oil

Lauric acid imparts soapy taste to edible oil and to fried bread in the concentration of less than 1 g·kg^-1, palmitic acid and stearic acid taste neutral in the concentration of up to 20 g·kg^-1, oleic acid is neutral in the same concentration range, while purified linoleic acid tastes slightly bitter, and the flavour of linolenic acid is bitter and rancid at the concentration of 1 g·kg^-1.     

Studies on rumen metabolism. IX. Contribution of plant lipases to the release of free fatty acids in the rumen

The role of plant lipases in the hydrolysis of dietary lipids in the rumen of pasture-fed ruminants has been investigated by means of in vitro and in vivo experiments with rumen contents. Lipases present in the leaves of numerous pasture plants remained highly active for at least 5 h in the presence of metabolising rumen microorganisms, leading to the hydrolysis of triglyceride. Parallel experiments showed that the lipase activity of actively metabolising micro-organisms in rumen fluid was very low. A slight increase in lipolytic activity attributable to micro-organisms occurred after incubations of about 4 h with plant extract when the metabolic activity of the microbial population had passed its peak. In vivo experiments showed that the lipolytic activity of rumen fluid, obtained 0.5 to 5.0 h after feeding fresh grass, was about twice that of rumen fluid obtained after overnight fasting. Paired feeding experiments showed that lipase activity was higher in rumen fluid obtained from a pasture-fed, than from a hay-fed animal. Nevertheless, there was appreciable activity in the rumen contents obtained from the hay-fed twin, which is consistent with the presence of lipase activity in the extracts of dried grass. Multiple forms of plant esterases and phosphatases were present in the soluble fraction of rumen fluid several hours after feeding. It is concluded that the rapid release of free fatty acids which follows the ingestion of pasture is due mainly to the activity of plant enzymes and that rumen microorganisms have a subsidary role in hydrolysing ingested lipid.     

烹饪方式对胡麻油不饱和脂肪酸的影响

通过设计不同温度下、不同加热时间、冷锅冷油及热锅冷油试验,分析其对胡麻油不饱和脂肪酸的影响。结果表明:不同加热温度、时间对胡麻油不饱和脂肪酸影响显著,随着加热温度的升高,不饱和脂肪酸含量有下降趋势,相同加热温度下时间越长,不饱和脂肪酸含量下降越快。冷锅冷油和热锅冷油的烹饪方式对胡麻油不饱和脂肪酸影响差异不显著,随着加热温度的升高,某未知物质有了显著升高,冷锅比热锅更容易生成该物质且变化明显。加热温度、加热时间与胡麻油不饱和脂肪酸呈负相关性。     

Development and origin of the volatile fatty acids in budu

The origin and mechanism of formation of the volatile fatty acids (VFA) present in budu were investigated. The acids did not appear to derive from the breakdown of the fish lipid. When the fish was allowed to spoil, a single bacterial species predominated, and as the fermentation progressed, the appropriate VFA were formed. Using (U^?14C)-protein hydrolysate it was shown that amino acids are the precursors of the n-butanoic and n-pentanoic acid and also contributed to the formation of other acids. The bacterium did not use glucose as a carbon source nor did any particular combination of unlabelled amino acids produce the fatty acids. The metabolic route by which the fatty acids are produced from the amino acids is not known. An experiment that allowed spoilage to occur, prior to salting, in the normal environment involved in the preparation of budu, showed that the VFA were produced.     

加热对油茶籽油中反式脂肪酸形成的影响

通过研究不同加热条件下(200、260、300℃)油茶籽油中脂肪酸组成,来分析反式脂肪酸形成和变化特征。结果表明,加热温度和加热时间是导致油茶籽油中反式脂肪酸形成和变化的影响因素。随着加热温度的升高和时间的延长,反式脂肪酸含量和种类有增加的趋势;而且反式脂肪酸的种类和含量还受未加热油茶籽油中顺式脂肪酸的影响。因此,在油茶籽油烹饪过程中,应掌握好加热温度和时间,以避免形成反式脂肪酸。     

Studies of the effects on the fermentation pattern in the rumen of the addition of various sources and levels of the lower volatile fatty acids

The short term effects on rumen fermentation of the direct addition to the rumen of 1·5 M and 3 M of acetate, propionate and butyrate, given as the Ca²⁺, Na⁺, and NH⁺₄ salts and as the free acid were measured in a mature cow. Longer term effects of the oral addition of I·5 M of calcium and ammonium acetates were also measured in growing heifers. For all volatile fatty acids (VFA) each rate of addition consistently increased the level of VFA in rumen liquor, but these fell gradually over about 4 h. Total volatile fatty acids (TVFA) were lower when free acids were given than when their salts were used. There was little effect on rumen pH. Calcium acetate was unpalatable when offered orally, and it tended to depress TVFA levels. Mean effects of acetate salts given orally on molar percentage of acetate in rumen liquor were smaller than those found by direct addition.     

油脂脱色过程对反式酸形成和不饱和度的影响

脱色过程对油脂的品质具有多方面的影响,吸附剂在发生吸附的同时对油脂的分解和脂肪酸的异构化等反应具有一定的催化作用。采用FT-IR检测技术对油脂脱色过程中反式酸和不饱和度的变化进行了综合评价,在油脂脱色体系中,脂肪酸异构化反应是温度和吸附剂共同作用的结果,吸附剂在此过程中起到了催化作用,温度对反式酸的形成起到了关键作用,脱色过程对亚油酸和亚麻酸等多烯脂肪酸的破坏导致了油脂总不饱和度的降低。     

Production of volatile fatty acids in the rumen and cecum-colon of steers as affected by forage:concentrate and forage physical form

Contribution of cecal and ruminal VFA to metabolizable energy was investigated in steers with cannulas in both the rumen and cecum. Animals were fed ad libitum so that data would be applicable to the lactating dairy cow. Diets assigned within a 4 x 4 Latin square were: 20% long alfalfa hay and 80% concentrate; 15% pelleted alfalfa, 5% hay and 80% concentrate; 80% hay and 20% concentrate; 60% pellets, 20% hay and 20% concentrate. Intake of DM was unaffected by diet. Cecal fluid pH, osmolality, and concentrations of valerate and isovalerate were unaffected by diet. Concentrations of total VFA, acetate, propionate, butyrate, and lactate in the cecum increased with proportion of grain in the diet. The high grain diets depressed cecal ammonia concentration and acetate to propionate ratio. Acetate production in the cecum was higher with the high grain diets whereas that in the rumen was lower. Production of propionate and butyrate in both the cecum and rumen was unaffected by diet. Cecal VFA provided 8.6% of metabolizable energy intake, on average. Contribution of ruminal VFA to total metabolizable energy was affected by diet, accounting for 72, 51, 74, and 52% of metabolizable energy from the 20% hay, 20% pelleted alfalfa, 80% hay, and 80% pelleted alfalfa, respectively. Cecal VFA were an important source of energy for ad libitum-fed steers; this contribution would undoubtedly increase with increasing feed intake.