Fermentation of liquid coproducts and liquid compound diets: Part 1. Effects on chemical composition during a 6-day storage period

The effects of a 6-day storage period on changes in dry matter, crude ash, crude protein, true protein, crude fat, starch, soluble starch, sugar and lactose of three liquid coproducts and two liquid compound diets were studied. The three liquid coproducts studied were: liquid wheat starch (LWS), mashed potato steam peel (PSP) and cheese whey (CW), and the two liquid compound diets were: liquid grower diet (LGD) and liquid finisher diet (LFD). The loss of corrected dry matter after a 6-day storage, expressed in relation to the initial content, was 1.9, 6.2, 9.6, 4.6 and 4.2% for LWS, PSP, CW, LGD and LFD, respectively. During storage, the total amount of starch decreased 2.7, 24.0, 28.1 and 33.3% for LWS, PSP, LGD and LFD, respectively. The total amount of lactose decreased 23.5% for CW. The gross energy value of the products did not change remarkably during the 6-day storage period; gross energy losses being less than 3% of the initial gross energy content.     

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

Three rumen fistulated wethers consumed a roughage (1200 g artificially dried grass) or a concentrate/roughage diet (600 g concentrate, 400 g dried grass per animal and day). The diets were unsupplemented or 0.5, 1 or 2 g choline per animal and day were added. After a 14-day feeding period, samples of rumen liquid were taken 0, 1, 2, 3, 4 and 6 h after morning feeding. In a second experiment, untreated and ammonia-treated wheat straw were incubated in nylon bags for 6, 12, 24, 48 and 72 h in rumen of 5 sheep fed on 1.2 kg dried grass and without or with 1 g choline per day. Choline supplementation decreased the total concentration of volatile fatty acids in rumen liquid in both types of diet (roughage: 106, 83, 89 and 87; concentrate/roughage: 142, 114, 91 and 106 mmol/l for 0, 0.5, 1 and 2 g choline per day resp.). Concentration of acetate and branched chain fatty acids in both diets and butyrate in concentrate/roughage diet was reduced as total acids. Butyrate in roughage diet was increased by added choline. Molar propionate concentration was not significantly influenced by choline (P greater than 0.05). Choline resulted in a little increase (P greater than 0.05) of dry matter degradability in rumen, especially when NH3-treated straw was incubated. The effect of choline on milk fat production of cows fed with diets rich in concentrate is probably not related to changes in rumen fermentation and digestion.     

嗜热链球菌产酸特性及其发酵乳中有机酸组分分析

选取实验室分离自自然发酵乳制品中的5株嗜热链球菌菌株为研究对象,进行单菌株发酵酸乳,在发酵期间和酸乳4℃贮藏504 h阶段,分别测定菌株发酵时间、滴定酸度、pH值、活菌数以及采用反相高效液相色谱法测定有机酸含量变化,研究嗜热链球菌发酵产酸特性及其酸乳贮藏期间后酸化及其有机酸组分的变化特性。结果表明：在42℃发酵期间,5株菌在发酵2h后pH值迅速下降,达到发酵终点时间在5～9h,发酵时间最短的是菌株IMAU10632和IMAU20772。在4℃贮藏504h期间,5株菌的pH值下降幅度在0.5左右,最终pH值稳定在4.2左右,产酸速度均较缓慢,均表现出嗜热链球菌后酸化能力弱的特点,且酸度值均在90oT以下。初步筛选出一株菌株IMAU10632,凝乳时间短、产酸速率快、后酸化能力较弱,在4℃贮藏期间活菌数维持在108CFU/mL以上。     

Performance and energy metabolism in restrictively fed weanling pigs are not affected by feeding either fermented cereals or their end‐products

To study the effects of feeding fermented cereals or just fermentation end‐products on performance and energy metabolism, 18 restrictedly fed groups of eight pigs each were assigned to one of three dietary treatments: (i) a liquid control diet (C) containing 40% of a mixture of barley and wheat; or (ii) a liquid diet (F) containing 40% fermented barley and wheat; or (iii) a liquid diet as C with the addition of some important fermentation end‐products (FP; organic acids and ethanol) in concentrations similar to those in the fermented F‐diet. Energy and nitrogen balances, heat production, and performance traits were measured during two consecutive periods (days 1–5 and days 6–14). There was a considerable increase in average dry matter intake that tended (p = 0.06) to be higher in the FP‐group than in the other groups. Apparent fecal digestibility of dry matter, ash, nitrogen and energy during period 2 were not affected (p > 0.1). Averaged over both periods, none of the energy metabolism parameters were affected by the diets (p > 0.1). However, there were diet × period interactions for metabolizable energy‐intake (p = 0.07), energy retention (p < 0.05), the respiratory quotient (RQ; p < 0.01) and activity‐related heat production (H_ACT, p = 0.05). Additionally, there were some differences between the diets in the average hourly patterns in RQ and H_ACT. In conclusion, restricted feeding of either 40% fermented cereals nor their fermentation end‐products affected performance and energy metabolism traits in weanling pigs. Nevertheless, lower postprandial activity‐related heat production by pigs given the fermented cereals suggest a stimulating effect of fermented cereals on short term satiety that was not seen in pigs given fermentation end‐products only.     

Gut ecology, feed digestion and performance in weaned piglets fed liquid diets

Gut environment and microflora, digestibility, and performance were studied in weaned piglets in Central Vietnam fed a dry control diet (CO), a naturally fermented liquid diet (FE), and a liquid diet with inclusion of rice distiller's residue (RDR). Digesta samples were collected at the start (day 0) and at the end of experiment (day 42). Diet FE had a lower pH than diet RDR, contained more organic acids, had the lowest counts of E. coli and total coliforms (P < 0.05), and the highest counts of lactic acid bacteria (LAB) (P < 0.05). Piglets fed diets FE and RDR had lower pH (P < 0.05), and higher concentrations of organic acids in the stomach, ileum and mid-colon (P < 0.05) than piglets fed diet CO. Counts of LAB in stomach and ileum were higher in animals fed diets FE and RDR than CO (P < 0.05), while the number of E. coli and total coliforms along the gastrointestinal tract was reduced. The ileal digestibility of crude protein and organic matter was improved in piglets fed diet RDR (P < 0.05) compared with piglets fed diet CO. Piglets fed diet RDR had a higher weight gain (P < 0.05) and a better feed utilization (P < 0.05) than piglets fed the other diets. The present findings support the contention that fermented diets and/or fermented feedstuffs can be used for dietary manipulation to improve gut health and animal performance.     

Fermented liquid feed and fermented grain to piglets- effect on gastrointestinal ecology and growth performance

A study was carried out to determine the microbial and nutritional characteristics of dry feed, liquid feed containing fermented liquid cereal grain, and fermented liquid compound feed, and their effect on gastrointestinal ecology and growth performance of piglets. Three dietary treatments were designed: dry feed (DRY); fermented liquid cereal grain feed (FLG); and fermented liquid feed (FLF). The FLF was prepared by removing three times daily 50% of the mixture (feed and water) stored in a tank at 20 °C and replacing it with an equal amount of fresh feed and water. The FLG was similarly prepared but fermenting only the cereals (barley and wheat) and adding the remaining ingredients immediately before feeding. One hundred and twenty weaners were fed the diets during 6 weeks from weaning. The dietary content of lysine (g/100 g protein) was 6.01 in the DRY diet, 6.21 in the FLG diet, and 5.46 in the FLF diet. Feeding piglets with the FLG diet resulted in a higher density of yeasts, a higher concentration of ethanol in the GIT, and a change of the bacterial population of the stomach compared to feeding FLF. The FLG group had a numerically higher daily feed intake and daily body weight gain compared to the FLF group, but the values were not significant. Feeding liquid feed containing fermented liquid cereal grains as a means of avoiding microbial degradation of free amino acids in the feed and increasing feed intake by improving palatability seems promising.     

Dietary carbohydrates affect caecal fermentation and modify nitrogen excretion patterns in rats. I. Studies with protein-free diets.

In a two-factorial experiment on 96 young male rats, the effects of substituting 10% raw potato starch (PS), pectins (PEC), or cellulose (CEL) for corn starch (CS) were studied using an unsupplemented protein-free (PF) diet or a PF diet supplemented either with DL-methionine or urea. The pH and the short chain fatty acids (SCFA) content in caecal digesta, as well as caecal digesta and tissue weights were determined and used as the criteria of caecal fermentation intensity. Blood urea level, amount of N excreted via faeces and urine, DAPA content, and amino acid composition of faecal protein were analyzed as indices of protein metabolism. A 10-day adaptation period to the carbohydrates fed with the casein diet preceded the experimental period of feeding the respective carbohydrates with protein-free diets. Dietary carbohydrates significantly influenced total and individual SCFA content in caecal digesta, as well as other parameters related to the intensity of fermentation. Potato starch and pectins were more intensively fermented than cellulose. Supplementation of the PF diet with methionine and urea affected only caecal isobutyric and valeric acid content in a way dependent on the carbohydrates present in the diet. Carbohydrates significantly altered the routes of N excretion. Faecal excretion was increased by all carbohydrates studied compared to corn starch, pectins had the most marked effect. Urinary excretion was significantly increased by cellulose (as compared with the PEC and PS groups) and decreased by pectins as compared with all other groups. There was an interaction between the effects of carbohydrates and type of protein-free diet on faecal and urinary excretion. The sum of amino acids in faecal protein was the lowest on the PEC diet, but the amino acid composition expressed as a per cent of total amino acid content was similar in all groups. It can be concluded that dietary carbohydrates alter the excretion patterns of endogenous nitrogen in rats in different ways and that this effect is related to the intensity of their fermentation in the hind gut.     

The effect of monensin on the fermentation of feed with different proportions of hay and concentrate in an artificial rumen (rumen simulation technic)

An experiment was conducted with rumen pouch (RUSITEC--Rumen Simulation Technique). In four fermentation vessels (V), percent proportions of hay and barley were as follows: V1--40:60, V2 - 60:40, V3--80:20 and V4--100:0. Every day 5 mg of monensin dissolved in 1 ml 96% ethanol were added to each fermentation vessel. All diets were isonitrogenous, and after an addition of urea the crude protein (CP) content made 13% in each diet. The experiment lasted 12 days: so called steady state period took the first six days when the fermentation conditions were stabilized. Monensin reduced dry matter digestibility, production of total volatile fatty acids, acetic acid, n-butyric and isovaleric acids and acetate: propionate proportion, and it increased the production of propionic and n-valeric acids. The production of methane and CO2 decreased. The higher proportion of hay in diets decreased dry matter digestibility, digestibility of detergent fibre, total and individual volatile fatty acids, CO2, methane energy yield of volatile fatty acids (E), glucose utilization, production of adenosine triphosphate and production of fermented hexoses. The production, utilization and recovery of metabolic hydrogen also decreased. The effectiveness of microbial matter synthesis (YATP = 11.3) was highest during the fermentation of feed containing 60% hay and 40% barley.     

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 genotype and diet on steer performance, manure odor, and carriage of pathogenic and other fecal bacteria. III. Odorous compound production

Three beef cattle diets were assessed for their potential to produce odorous compounds from cattle feces excreted during the growing and finishing periods. Eight pens containing 51 steers of varying proportions of Brahman and MARC III genotypes were fed either a chopped bromegrass hay diet or a corn silage diet for a 119-d growing period. After the growing period, all steers were switched to the same high-corn finishing diet (high corn) and fed to a target weight of 560 kg (finishing period). Fecal slurries were prepared from a composite of fresh fecal pats collected in each pen during both periods and incubated anaerobically. In additional flasks, starch, protein, or cellulose was added to the composite fecal subsamples to determine the preferred substrates for fermentation and odorous compound production. The content and composition of the fermentation products varied both initially and during the incubation, depending on the diet fed to the steers. The corn silage and high corn feces had the greater initial content of VFA (381.0 and 524.4 micromol/g of DM, respectively) compared with the bromegrass feces (139.3 micromol/g of DM) and accumulated more VFA than the bromegrass feces during the incubation. l-Lactic acid and VFA accumulation in the high corn and corn silage feces was at the expense of starch, based on starch loss and the production of straight-chain VFA. In the bromegrass feces, accumulation of branched-chain VFA and aromatic compounds and the low starch availability indicated that the protein in the feces was the primary source for odorous compound production. Substrate additions confirmed these conclusions. We conclude that starch availability was the primary factor determining accumulation and composition of malodorous fermentation products, and when starch was unavailable, fecal microorganisms utilized protein.     

Fibre degrading enzymes and Lactobacillus plantarum influence liquid feed characteristics and the solubility of fibre components and dry matter in vitro

The effect of fibre degrading enzymes in combination with Lactobacillus plantarum on feed viscosity and pH and on solubilisation of non-starch polysaccharides (NSP) was studied in vitro using diets composed of cereals and soybean meal. The diet was incubated over time up to 24 h as liquid feed or liquid feed added L. plantarum and in addition both feeds were treated without or with fibre degrading enzymes.

Spontaneous fermentation developed in the liquid feed without L. plantarum and became noticeable after a period of 6 to 8 h, when pH began to drop. From 8 to 24 h there was a slow but steady reduction in pH down to a level of about pH 4.3. This development was irrespective of enzyme supplementation level. The L. plantarum treatment had already reached a pH of 4.2 after 8 h and a pH of 3.6 after 24 h.

The viscosity was reduced with supplementation with a high enzyme dose (6000 FXU and 600 FBG per kg diet), compared to the control diet (without enzymes). Treatment with L. plantarum (1.8 × 1011 CFU/kg feed) increased the viscosity over time, even with enzyme supplementation, compared to the control treatment.

Diets without and with enzyme supplementation and pre-treated as dry feed (control), liquid feed (incubated for 8 h) or liquid feed fermented with L. plantarum (incubated for 24 h), were subjected to an in vitro digestion procedure. Both pre-treatment as liquid feed and enzyme supplementation lead to a reduction in dry matter and in the insoluble NSP fraction during digestion in comparison with the control based on the original dry feed.

It may be concluded that enzyme supplementation to liquid or fermented feed may cause a reduction in the insoluble dietary fibre content as well as a reduction in feed viscosity, while the pH is not influenced.     

Effect of feeding fermented liquid feed and fermented grain on gastrointestinal ecology and growth performance in piglets

To investigate the microbial and nutritional characteristics of dry feed, liquid feed containing fermented liquid cereal grains, and fermented liquid feed, and their effect on gastrointestinal ecology and growth performance, 120 piglets from 40 litters were used and housed in pens with 5 animals in each. The 3 dietary treatments (all nonheated and nonpelleted diets) were: a dry meal diet (DRY); a fermented, liquid cereal grain feed (FLG); and a fermented liquid feed (FLF). The FLG diet was prepared by storing the dietary cereals (barley and wheat) and water (1:2.5, wt/wt) in a closed tank at 20 degrees C and adding the remaining dietary ingredients immediately before feeding. The FLF diet was prepared by storing compound feed and water (1:2.5, wt/wt) in a closed tank at 20 degrees C. Three times daily, 50% of the fermented cereals or compound feed and water stored in the tanks was removed and replaced with an equal amount of fresh cereals or feed and water. On d 14, 1 piglet from each pen was killed and samples from the gastrointestinal tract were obtained. The pH of the fermented cereals was 3.85 (SD = 0.10), that of the FLG diet was 5.00 (SD = 0.18), and the pH of the FLF diet was 4.45 (SD = 0.11). The dietary concentration of lysine (g/16 g of N) pointed to a decreased concentration in the FLF (5.46, SD = 0.08) compared with the DRY (6.01) and FLG (6.21, SD = 0.27) diets, and the concentration of cadaverine was greater in the FLF diet (890 mg/kg, SD = 151.3) than in the DRY (32 mg/kg) or FLG (153 mg/kg, SD = 18.7) diets. Fermenting only the cereal component of the diet (FLG) promoted the growth of yeasts to a greater extent than fermenting the whole diet (FLF). Terminal RFLP profiles of diets and digesta from the stomach and midcolon showed differences among dietary groups. The number of yeasts able to grow at 37 degrees C in the stomach and caudal small intestine was greatest in the FLG group compared with the other 2 dietary groups (P < 0.01). In the cecum and colon, the differences were only significant between piglets fed the FLG and the FLF diets (P < 0.05). The greatest number of yeasts able to grow at 20 degrees C was detected in the animals fed the FLG diet. However, the values were different from the FLF-fed piglets only in the stomach (P < 0.05) and midcolon (P < 0.05). There was a tendency (P < 0.10) for greater ADG of the piglets fed the FLG compared with the FLF diet. Feeding liquid feed containing fermented, liquid cereal grains as a means of avoiding microbial decarboxylation of free amino acids in the feed and increasing feed intake by improving palatability seems promising but requires further investigation.     

Effects of nonstructural carbohydrates and protein sources on intake, apparent total tract digestibility, and ruminal metabolism in vivo and in vitro with high-concentrate beef cattle diets

To investigate the effects of synchronizing nonstructural carbohydrate (NSC) and protein degradation on intake and rumen microbial fermentation, four ruminally fistulated Holstein heifers (BW = 132.3 +/- 1.61 kg) fed high-concentrate diets were assigned to a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments studied in vivo and in vitro with a dual-flow continuous culture system. Two NSC sources (barley and corn) and 2 protein sources [soybean meal (SBM) and sunflower meal (SFM)] differing in their rate and extent of ruminal degradation were combined resulting in a synchronized rapid fermentation diet (barley-SFM), a synchronized slow fermentation diet (corn-SBM), and 2 unsynchronized diets with a rapidly and a slowly fermenting component (barley-SBM, and corn-SFM). In vitro, the fermentation profile was studied at a constant pH of 6.2, and at a variable pH with 12 h at pH 6.4 and 12 h at pH 5.8. Synchronization tended to result in greater true OM digestion (P = 0.072), VFA concentration (P = 0.067), and microbial N flow (P = 0.092) in vitro, but had no effects on in vivo fermentation pattern or on apparent total tract digestibility. The NSC source affected the efficiency of microbial protein synthesis in vitro, tending to be greater (P = 0.07) for barley-based diets, and in vivo, the NSC source tended to affect intake. Dry matter and OM intake tended to be greater (P > or = 0.06) for corn- than barley-based diets. Ammonia N concentration was lower in vitro (P = 0.006) and tended to be lower in vivo (P = 0.07) for corn- than barley-based diets. In vitro, pH could be reduced from 6.4 to 5.8 for 12 h/d without any effect on ruminal fermentation or microbial protein synthesis. In summary, ruminal synchronization seemed to have positive effects on in vitro fermentation, but in vivo recycling of endogenous N or intake differences could compensate for these effects.     

Effects of graded levels of liquid brewer's yeast on chemical composition and fermentation quality in cassava pulp and rice straw‐based total mixed ration silage

This study aimed to evaluate the effect of liquid brewer's yeast (LBY) addition on chemical composition and fermentation quality of mixture of LBY and cassava pulp (CVP) with rice straw (RS) in different ratios during preservation periods. Four mixtures of LBY, CVP and RS were made, that is mixture ratio of LBY : CVP : RS of 0% LBY, 20% LBY, 35% LBY and 50% LBY were 0:70:30, 20:50:30, 35:35:30 and 50:20:30 as fresh matter, respectively. The bags were opened at weeks 0, 1, 2, 4 and 8 after storage. The contents of dry matter, organic matter, crude protein (CP), ether extract (EE), neutral detergent fiber and acid detergent fiber ranged 36.4‐40.0, 88.9‐90.8, 4.0‐12.0, 1.1‐1.3, 58.8‐61.6 and 37.6‐40.0, respectively, and the contents of CP and EE increased and the other components decreased in proportion to LBY inclusion (P < 0.01). 50% LBY had the highest (P < 0.05) pH (4.81) and ammonia nitrogen per total nitrogen (NH₃‐N/TN) (7.40%) and the lowest V‐score (90.3). Propionic and butyric acid contents were 0.01% or lower in each mixture and storage period. There were rapid pH decrease and NH₃‐N/TN increase during the first week of the storage period. The increases of NH₃‐N/TN and acetic acid content and decreases of pH, lactic acid content and V‐score during the preservation were more drastic as LBY inclusion increased. Although higher proportion of LBY produced higher CP and lower fiber contents in the mixture, attention should be paid for the reduction of fermentation quality during longer storage periods.     

Relationship between thiamine concentration and fermentation patterns in the rumen fluid of dairy cows fed with graded concentrate levels

The objective of this study was to investigate the relationship between the thiamine concentration and the fermentation patterns [pH, concentration of short-chain fatty acids (SCFA)] in the free liquid (FRL) and particle-associated liquid (PARL) of the rumen in dairy cows fed with graded concentrate levels in the diet. Four ruminally cannulated Holstein cows in mid lactation were fed [semi-ad libitum, 18 kg dry matter (DM)/day] diets consisting of hay (H) and slowly degradable concentrate (C), offered in five different H:C ratios (% DM basis) in the following sequence: period 1, 30:70; period 2, 40:60; period 3, 50:50; period 4, 60:40 and period 5, 75:25. A negative quadratic relationship was observed between thiamine concentration in FRL and intake of dietary thiamine (R(2) = 0.36), of concentrate (R(2) = 0.38) and of digestible non-fibre carbohydrates (R(2) = 0.37). The thiamine concentration in PARL was higher (p < or = 0.05) compared to FRL. The ruminal thiamine concentration correlated negatively to pH and positively to concentrations of SCFA and propionate in the rumen. R(2) of these relationships varied markedly (0.002 and 0.77), depending on time after feeding and fluid digesta compartment. The higher R(2) were observed at 8 and 11 h after the morning feeding for FRL (R(2) 0.46-0.71) and PARL (R(2) 0.41-0.77), respectively.     

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.     

Effect of sodium bicarbonate and sodium bentonite on digestion, solid and liquid flow, and ruminal fermentation characteristics of forage sorghum silage-based diets fed to steers

Six ruminally cannulated steers, five Holsteins and one Hereford (250 to 295 kg), were fed 84% forage sorghum silage plus 16% supplement or 50% forage sorghum silage plus concentrate and supplement diets containing either no addition (controls), 1% sodium bicarbonate (NaHCO3) or 2% sodium bentonite in a 2 X 3 factorial arrangement of treatments in a 6 X 6 Latin-square experiment with 3-wk periods. Sodium bicarbonate increased dry matter (DM) intake when concentrate was included, but neither compound affected intake of the 84% silage diet. Bentonite lowered DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibilities, but NDF disappearance from nylon bags was unchanged. Ruminal pH, osmolality and L(+) and D(-) lactate were not affected by treatment. Both NaHCO3 and bentonite tended to lower ruminal NH3-N concentrations. Bentonite lowered the molar proportion of isobutyrate in ruminal fluid relative to controls, but proportions of other volatile fatty acids (VFA) and total VFA concentrations were unchanged. Neither NaHCO3 nor bentonite affected ruminal liquid or solid volumes, dilution rate constants or ruminal outflow rates. Markers overestimated volumes, but correction with measured volumes did not change interpretation of treatment effects. It was concluded that control diets had sufficiently high baseline values of pH, dilution rate and acetate proportion to preclude changes induced by either compound, especially at 1 or 2% of DM intake. An effect on palatibility through neutralization of silage acids may have been responsible for the intake response to NaHCO3.     

枣粉与包被蛋氨酸对育肥牛生长性能、养分表观消化率、瘤胃发酵和血清生化指标的影响

本试验旨在研究饲粮添加枣粉(JP)和包被蛋氨酸(CMet)对育肥期肉牛生长性能、养分表观消化率、瘤胃发酵和血清生化指标的影响。采用双因子试验设计,试验因素分别为JP(JP替代饲粮玉米比例为0或15%,JP-/JP+)和CMet(饲粮添加0或1.08 g/kg蛋氨酸有效成分,CMet-/CMet+)。将20头月龄与体重相近的育肥期肉牛(西门塔尔×本地黄牛)随机分为4组,分别饲喂基础饲粮、基础饲粮+JP、基础饲粮+CMet以及基础饲粮+JP+CMet,每组5个重复,每个重复1头牛。试验期共70 d,其中预试期10 d,正试期60 d。结果表明：1)饲粮添加JP显著提高了干物质采食量和平均日增重(P <0.05);而添加CMet仅显著提高了平均日增重(P <0.05);JP与CMet对生长性能互作效应不显著(P>0.05)。2)饲粮添加JP显著提高了粗蛋白质、酸性洗涤纤维和非纤维碳水化合物表观消化率(P<0.05);饲粮添加CMet则显著提高了粗蛋白质、有机物和非纤维碳水化合物表观消化率(P<0.05);JP与CMet对粗蛋白质和非纤维碳水化合物表观消化率互作效...     

Effect of cooking and fermentation of a pig diet on gut environment and digestibility in growing pigs

The effect of pre-feeding treatment of a pig diet on gut environment and digestibility was studied in a double 3 × 3 Latin-square experiment using growing castrated PVTC cannulated male pigs. The diets were based on local feed resources and were fed raw (R), cooked (C) or naturally fermented (F). There were no differences (P > 0.05) in pH and butyric acid concentration of ileal digesta between diets. However, on diet F concentrations of acetic, lactic and propionic acid in ileal digesta were higher (P < 0.05) than on diets R and C. The relative proportions of individual organic acids in ileal digesta were not a reflection of the fermentation profile found in diet F. The ileal apparent digestibility of crude protein, crude fiber and NDF were higher (P < 0.05) on diet F than on diets R and C. The total tract apparent digestibility of crude protein was higher (P < 0.05) on diet F diet than on diets R and C, while there were no differences in total tract apparent digestibility between diets for any other dietary component. In conclusion, when compared with a pig diet in the raw form, fermentation influenced the gut environment and improved the digestibility of some dietary component, while cooking prior to feeding had no measurable effects.     

Rumen fermentation pattern of dairy heifers fed restricted amounts of low, medium, and high concentrate diets without and with yeast culture

Restricted feeding and high concentrate diets are potential strategies for growing dairy heifers. Ruminal manipulation with additives such as Saccharomyces cerevisiae yeast culture (YC) has been shown to alter digestibility when added to this type of diet. An experiment was conducted to investigate the ruminal fermentation and in situ digestibility of diets with 3 different levels of forage to concentrate (F:C) fed at restricted intake without and with YC addition. Three cannulated post-pubertal Holstein heifers (age 18.0 ± 1.2 months; body weight 449.6 ± 19.7 kg) were fed diets consisting of corn silage as the sole forage source in a 3 period (35-day) Latin square design. Heifers were fed diets for 21 days with no YC addition, followed by 14 days where YC was added to the diet (1 g/kg as fed basis). Low (LC), medium (MC), and high (HC) concentrate diets (20, 40, and 60% concentrate) were fed once daily on a restricted basis to provide 0.22 Mcal ME/kg empty BW^0.75. Rumen fluid was sampled on days 18 and 32 of each period, and rumen contents were evacuated on days 21 and 35 of each period. An in situ study was done on days 14 to 17 and on days 28 to 31. Mean ruminal pH was not different between dietary treatments and no YC effect was detected. Mean total volatile fatty acids (VFA) and ruminal ammonia-nitrogen (NH₃-N) concentration was also not different among diets with different F:C. Molar proportions of acetate were decreased, and propionate were increased; while the acetate-to-propionate ratio was decreased as the concentrate level increased from LC to HC. Total VFA, propionate, and acetate as well as isoacids concentration increased, yet NH₃-N concentration decreased with YC addition in all diets. From these results we conclude that feeding HC diets in restricted amounts had minimal effects on rumen fermentation rate between different F:C diets. The addition of YC modified NH₃-N and volatile fatty acid concentrations in the rumen in all 3 diets in this study, presumably through alterations in end-product production and utilization.