Fatty acid composition of ruminal bacteria and protozoa,and effect of defaunation on fatty acid profile in the rumen with special reference to conjugated linoleic acid in cattle

Objectives of this study were to compare fatty acid (FA) composition of ruminal bacterial (B) and protozoal (P) cells, and to investigate effect of protozoa on FA profile in the rumen of cattle. Three cows were used to prepare ruminal B and P cells. Four faunated and three defaunated cattle (half‐siblings) were used to study effect of protozoa on ruminal FA profile. Proportions of C16:0 and C18:0 in total fatty acids in B cells were 20.7% and 37.4%, whereas those in P cells were 33.4% and 11.6%, respectively. Proportions of trans‐vaccenic acid (VA) and cis‐9, trans‐11 conjugated linoleic acid (CLA) in B cells were 3.9% and 1.0%, and those in P cells were 5.5% and 1.6%, respectively, being higher in P cells. Proportions of C18:1, C18:2 and C18:3 in P cells were two to three times higher than in B cells. Proportions of unsaturated fatty acids, VA and CLA in B cells of faunated cattle were higher than those of defaunated. VA and CLA in the ruminal fluid of faunated were also 1.6 to 2.5 times higher than those of defaunated. This tendency was similar for cell‐free fraction of ruminal fluid. These results indicate that protozoa contribute greatly in VA and CLA production in the rumen.     

Effects of protozoa on the antioxidant activity in the ruminal fluid and blood plasma of cattle

The objective of this study was to investigate the antioxidant status in ruminal fluid and blood plasma among three faunated and two defaunated (protozoa‐free) cattle (average bodyweight of 225 kg), fed hay plus concentrate. The extra cellular antioxidant activity of the mixed protozoa and bacteria suspensions were also studied in vitro. The antioxidant activity was detected by means of the free radical scavenging ability. The activity (units/microbial nitrogen) of the protozoal suspension increased from 59 (0 h) to 318 (18 h), and decreased to 40 (24 h) during incubation. The activity of the bacterial suspension also increased from 111 (0 h) to 644 (18 h), and decreased to 533 (24 h). The antioxidant activity (units/mL, U/mL) in the ruminal fluid of faunated (ranging from 116 to 254) and defaunated (ranging from 66 to 110) cattle was increased after 2 h and decreased after 5 h of feeding, being significantly higher in the faunated cattle. The antioxidant activity of blood plasma (U/mL) ranged from 248 to 316 in the faunated and 121–170 in the defaunated cattle during 0–5 h after feeding, being significantly higher in the faunated cattle. Therefore, defaunation possibly causes a decrease in the antioxidant level in the ruminal fluid, and may impair the health and performance of ruminants through an oxidant–antioxidant imbalance.     

Effect of ruminal protozoa on fecal microbiota in cattle using terminal restriction fragment length polymorphism

The effect of the presence of ruminal protozoa on the composition of fecal microbiota in cattle was investigated. Six castrated Holstein cattle (mean bodyweight 137 kg) were divided into two groups: three faunated and three unfaunated. The fecal bacterial composition of the faunated and unfaunated cattle was compared using a culture method and by terminal restriction fragment length polymorphism (T‐RFLP) analysis. Approximately 0.4 to 2.3% of the bacterial cells detected by microscopy formed colonies on medium 10. The major terminal restriction fragments were detected in the T‐RFLP profiles generated by Hha I and Msp I digestion in both the faunated and unfaunated cattle. In particular, the Bacteroides group, the Clostridium coccoides group and the Clostridium leptum subgroup might be the known bacterial groups that protozoa influence by Msp I digestion. From the dendrogram analysis by T‐RFLP patterns, the faunated and unfaunated cattle were divided into two clusters, I and II, respectively. These results suggest that absence of protozoa in the rumen changes the composition of fecal bacteria.     

Comparative digestion of cell wall components of alfalfa hay cubes between Sika deer (Cervus nippon) and cattle

Four female Sika deer (mean bodyweight, 48 kg) and three male Holstein cattle (mean bodyweight, 209 kg) were offered alfalfa hay cubes at 2% (deer) and 2.5% (cattle) of bodyweight, respectively. The digestibility of the cell walls and cell wall components (rhamnose, arabinose, xylose, mannose, galactose and glucose) in alfalfa and its retention time of the alfalfa in the digestive tract and rumen parameters were determined. Cell walls and xylose were less digestible in the deer than in the cattle (P < 0.01 and P < 0.05, respectively). The digestibility of galactose in the deer was as high as that in the cattle. The digestibility of the other sugars and total neutral sugars was numerically lower in the deer, but the differences were not significant. In the deer, mannose was most digestible, followed in order by galactose, arabinose, glucose, rhamnose and xylose; whereas, in the cattle, mannose was most digestible, followed in order by arabinose, glucose, galactose, rhamnose and xylose. The retention time in the digestive tract was shorter in the deer than in the cattle. In the deer, the number of ruminal protozoa was somewhat higher, and the concentrations of propionic acid and butyric acid were higher (P < 0.05) than in the cattle. These results indicate that Sika deer might utilize pectic polysaccharides as a carbon source in preference to glucose containing polysaccharides such as cellulose. The lower digestibility of all cell wall components except galactose in the Sika deer might be mainly due to its shorter retention time.     

Pipecolic acid in rumen fluid and plasma in ruminant animals

A survey was conducted to investigate the physiological levels of pipecolic acid (Pip) in rumen fluid and plasma of ruminants such as goats and cattle in the presence or absence of rumen protozoa. The concentration of Pip was determined using HPLC. Basal Pip levels in the rumen fluid and plasma of normal faunated animals were 21 ± 8 and 2.3 ± 1.3 µM, respectively, and levels increased 1–2 h after feeding. The Pip levels in the rumen fluid and plasma of faunated goats and cattle were significantly higher than those of defaunated goats and unfaunated cattle. A small amount of Pip was also found in the rumen fluids of the defaunated and unfaunated animals; this appeared to be derived from feeds such as hay cube and corn silage. The results obtained in the present study suggest that a significant amount of rumen‐produced Pip is likely to be absorbed into the plasma of the host animals and that rumen protozoa significantly enhance the concentration of Pip in the rumen fluid and plasma of ruminant animals.     

Comparison of digestibility, passage rate and rumen fermentation between sika deer (Cervus nippon) and cattle fed alfalfa hay cubes

Five female sika deer and three male Holstein cattle were offered alfalfa hay cubes at 2% (deer) and 2.5% (cattle) of bodyweight, respectively. The passage rate through the digestive tract, digestibility and rumen fermentation of the animals were determined. The rate of ruminal passage was higher and the total mean retention time in the digestive tract was shorter in deer than in cattle. In addition, the rate of post‐ruminal passage in deer was lower. The digestibilities of dry matter, organic matter, crude protein and fiber in deer were significantly lower than in cattle (P < 0.05). The concentration of total volatile fatty acids in the rumen was significantly higher in deer than in cattle. The molar percentage of acetic acid was lower and that of valeric acid was higher in deer (P < 0.05). The number of protozoa was somewhat higher in deer. These results suggested that the lower digestibility in deer might be a result of the shorter retention time in the digestive tract.     

The mcrA gene and 16S rRNA gene in the phylogenetic analysis of methanogens in the rumen of faunated and unfaunated cattle

The influence of rumen protozoa on the composition of rumen methanogens was studied by using seven growing Holstein cattle divided into two groups: four faunated and three unfaunated. 16S ribosomal RNA gene (rDNA) and methyl coenzyme‐M reductase (MCR) α subunit (mcrA) gene clonal libraries were constructed. The results of each analysis showed that Methanobacteriales was dominant in the rumen of both groups. By mcrA gene analysis, 22.1% of unfaunated clones were classified into unfaunated group 1, which was not detected from faunated cattle. The 16S rRNA gene analysis showed that the number of operational taxonomic units was higher in unfaunated than faunated cattle, suggesting the diversity of methanogens tended to be higher by the removal of protozoa. The results of the LIBSHUFF program indicated that the 16S rRNA gene and mcrA gene clone libraries for the faunated group differed from those for the unfaunated group (P = 0.001). It was suggested that the presence of protozoa strongly affected the composition of rumen methanogens.     

Comparative Nutrient Digestibility in Blue Foxes (Alopex lagopus) and Mink (Mustela vison) Fed Diets with Diverging Fat: Carbohydrate Ratios

Abstract

Nutrient digestibilities were evaluated in comparative experiments with blue foxes and mink by using six diets differing in fat:carbohydrate (F:C) ratios. In mink, apparent digestibilities of N and amino acids decreased with decreasing F:C ratio. N digestibility, and most amino acid digestibilities, were higher in blue foxes than in mink (P < 0.01). Fat digestibility in mink, but not in blue foxes, declined as the F:C ratio decreased (P < 0.05). Fat digestibility was higher in blue foxes than in mink (P < 0.05). Carbohydrate digestibility was not affected by the F:C ratio, but high levels of carbohydrates were digested more completely by foxes than by mink. The use of mink digestibility values in feed evaluations for blue foxes will consequently underestimate digestibility. Thus, to evaluate feed correctly, separate digestibility determinations should be made for mink and foxes.     

Comparison of voluntary feed intake, rumen passage and degradation kinetics between crossbred Brahmam cattle (Bos indicus) and swamp buffaloes (Bubalus bubalis) fed a fattening diet based on corn silage

Three crossbred tropical cattle and three crossbred buffaloes, fitted with rumen cannulas, were used to investigate the differences in feed intake, digestibility and parameters with rumen degradation kinetics between cattle and buffalo fed a fattening diet in the Philippines. The animals were fed a diet consisting of 50% corn silage (CS), 30% brewer's grain (BG) and 20% concentrate mixture (CM) on a dry matter (DM) basis, at a level of 3% bodyweight (BW) as DM. Total DM intake (DMI) and rumen fill were greater (P < 0.05) for buffaloes than for cattle, but significant differences were not detected between the animal species when those were expressed as percentage of BW. The DMI per metabolic body size for BG and CM were greater for buffaloes than for cattle (P < 0.05), whereas that of CS did not differ between the species (P > 0.05). The weight proportion of consumed feedstuffs differed between cattle and buffaloes (P < 0.05), although nutrient intake per total DMI did not differ significantly (P > 0.05) between the animal species. Nutrients digestibility was higher (P < 0.05) for buffaloes than for cattle. Ruminal passage rate constant of feed particles and rumen fluid did not differ (P > 0.05) between the animal species. Higher DM degradation rate constant and effective degradability with CS were prominent for buffaloes than for cattle (P < 0.05). Degradation parameters did not differ (P > 0.05) between cattle and buffaloes, neither with BG nor CM. The results indicate that the greater digestibility with DM and energy for buffaloes are ascribable to greater effective degradability of CS fed ad libitum level.     

Ruminal ciliated protozoa in cattle fed finishing diets with or without supplemental fat

Ruminal samples were collected at slaughter from 364 unfasted steers fed different finishing diets to obtain information on numbers and species distribution of ciliated protozoa in feedlot cattle. Total numbers of protozoa averaged 1.59 X 10(5)/g of ruminal contents. A total of 47 steers (12.9%) were defaunated, but 4.1% of the steers possessed numbers of protozoa greater than 10(6)/g. Entodinium species did not always dominate the protozoan populations; 41 faunated steers (11.2%) were devoid of entodinia, and 79 additional steers (21.7%) possessed populations dominated (greater than 50%) by other genera. Isotricha was the most commonly occurring genus supplanting Entodinium, but Polyplastron and Epidinium were frequently present in high concentrations. Tallow and soybean soapstock supplementation reduced (P less than .05) numbers of protozoa in steers consuming wheat diets. However, yellow grease supplementation did not affect numbers of protozoa in steers fed either sorghum or corn diets. Average ruminal pH was 6.20 on the wheat diet, 6.05 on the corn diet, and 5.69 and 6.23 for the two sorghum diets, respectively. We found no correlation between ruminal pH and numbers of protozoa on any diet. The presence of relatively high protozoan concentrations and few defaunated animals in feedlot cattle necessitates reevaluation of the role that ciliated protozoa play in ruminal metabolism of animals fed processed, high-concentrate diets.     

Effects of protozoa on bacterial nitrogen recycling in the rumen

The effects of protozoa on ruminal NH3-N kinetics and bacterial N recycling were measured in five sheep (57.6+/-7.1 kg BW, x +/- SD) with ruminal and duodenal cannulas in naturally faunated, defaunated, and refaunated periods. The sheep were fed a diet of 239 g of alfalfa haylage and 814 g of barley concentrate per day (DM basis) divided into 12 equal portions and allocated at 2-h intervals. A pulse dose of 300 mg of 15N as [15N]NH4Cl was administered into the rumen (on d 1 and 15) and 300 mg of 15N as [15N]urea was administered intravenously to the blood (d 8). Enrichment of 15N was measured in ruminal NH3-N, bacterial N, and plasma urea N over a period of 35 h. Total collection of urine was made for 5 d and analyzed for purine derivatives to calculate the flow of microbial N. Ruminal parameters and nutrient digestibilities were also measured. Sheep were defaunated using a rumen washing procedure 50 d prior to measurements in the defaunated period. Sheep were refaunated with ruminal contents from a faunated sheep receiving the same diet. Measurements began 26 d following refaunation, at which time protozoal numbers had returned to those in the originally faunated sheep. Data reported in parentheses are for faunated, defaunated, and refaunated sheep, respectively. Total culturable and cellulolytic bacterial numbers were unaffected by defaunation, but there was an increase in flow of microbial N from the rumen (10.8, 17.3, and 11.1 g N/d; P < .05) in the defaunated period. Flux, irreversible loss, and intraruminal recycling of NH3-N and recycling of NH3-N from plasma urea N were not affected by defaunation. Defaunation had no effect on reducing the absolute amount (13.8, 10.0, and 11.3 g N/d; P > .20) of bacterial N recycling and the percentage of N flux through the bacterial N pool. Total-tract digestion was reduced in defaunated compared with faunated sheep by 8, 17, 15, and 32% for OM, N, NDF, and ADF, respectively. In conclusion, defaunation improved ruminal N metabolism through the enhancement of bacterial protein synthesis, and improvement in the flow of microbial protein to the host animal.     

Effects of adding urea on fermentation quality of pruned persimmon branch silage and its digestibility,preference, nitrogen balance and rumen fermentation in beef cattle

Four cattle were used in a 4 × 4 Latin square design experiment to study digestibility, ruminal fermentation, nitrogen retention and preference of ensiling pruned persimmon branch (PPB) chips treated with urea. After 60 days of ensiling, urea‐treated PPB showed higher (P < 0.05) pH, acetic acid and ammonia‐N levels than no‐urea PPB. Both urea‐treated PPB and rice straw diets showed higher (P < 0.05) apparent digestibility and digestible nutrient content in cattle than no‐urea PPB diet. Neither mold nor yeast was detected in any urea‐treated PPB. Urinary and fecal excretion as well as nitrogen retention in cattle fed urea‐treated PPB were higher (P < 0.05) than in those fed no‐urea PPB and rice straw. With the exception that ruminal ammonia‐N levels in cattle fed urea‐treated PPB were higher (P < 0.05) than in those given no‐urea PPB and rice straw, ruminal pH, volatile fatty acid concentrations, and the acetic : propionic acid ratio of rumen content were unaffected by diets. The rank order of preference was rice straw > low‐urea > no‐urea > high‐urea. The results suggested that urea treatment of PPB inhibited growth of mold and yeast during silage storage, enhanced its digestibility and had nutritive value almost equivalent to that of rice straw.     

Effects of urea and sodium bicarbonate supplementation of a high-fiber diet on nutrient digestion and ruminal characteristics of defaunated sheep.

Five sheep (average BW 48 kg) with ruminal, duodenal, and ileal cannulas were fed 63% roughage: 37% concentrate diets (CP = 14.5%) in a 5 x 5 Latin square design to study effects of urea and sodium bicarbonate supplementation on nutrient digestion and ruminal characteristics of defaunated sheep. Diets were fed twice daily (DMI = 1,076 g/d). Defaunation was accomplished with 25-ml doses of alkanate 3SL3/sheep daily for 3 d. Control sheep were faunated (Treatment 1) and fed soybean meal as the major N supplement. Remaining sheep were maintained defaunated and fed either the same diet as Treatment 1 (Treatment 2), Treatment 1 with urea replacing 30% of the soybean meal N (Treatment 3), or Treatment 1 with 2% sodium bicarbonate in the diet (Treatment 4). Treatment 5 was a combination of Treatments 3 and 4. Compared with the faunated control, defaunation decreased (P less than .05) total tract DM, OM, NDF, ADF, and CP digestibilities (71.5 vs 69.4, 73.8 vs 71.7, 64.6 vs 61.4, 58.7 vs 55.8, and 74.2 vs 70.6%, respectively) and average (2 to 12 h postfeeding) ruminal fluid ammonia (23.5 vs 13.7 mg/dl) and isobutyrate (.9 vs .7 mM) concentrations. However, defaunation increased (P less than .05) linoleic and linolenic acid flows (.58 vs .45 g C18:2/d; .17 vs .14 g C18:3/d) to and disappearance (.50 vs .39 g C18:2/d; .14 vs .11 g C18:3/d) from the small intestine. Urea supplementation increased (P less than .05) total tract DM (70.2 vs 68.6%) and OM (72.3 vs 71.0%) digestibilities of defaunated sheep but lowered (P less than .05) ruminal fluid isobutyrate concentration (.6 vs .8 mM). Sodium bicarbonate supplementation increased (P less than .05) ruminal fluid pH (6.4 vs 6.2), isobutyrate concentration (.75 vs .60 mM), total tract ADF digestibility (57.6 vs 54.2%), and ruminal NDF (41.6 vs 28.5%), ADF (36.6 vs 22.8%), and CP (-5.5 vs -26.8%) digestibilities in defaunated sheep. Dietary supplementation of urea or sodium bicarbonate increased nutrient digestion by defaunated sheep.     

Effects of Saccharomyces cerevisiae cell wall extract and poplar propolis ethanol extract supplementation on growth performance,digestibility, blood profile,fecal microbiota and fecal noxious gas emissions in growing pigs

A total of 105 growing pigs (24.91 ± 1.06 kg) were used in a 6‐week trial to investigate the effects of including Saccharomyces cerevisiae cell wall extract and poplar propolis ethanol extract (SPE) in the diet on growth performance, digestibility, blood profiles, fecal microbiota and fecal noxious gas emissions. Pigs were randomly allocated to one of three dietary treatments (seven pens/treatment, five pigs/pen) according to initial body weight and sex (two gilts and three barrows). Treatments consisted of a corn soybean meal basal diet supplemented with 0, 0.05 or 0.10% SPE. There was a significant linear improvement (P < 0.05) in average daily gain, gain/feed, the apparent total tract digestibility of dry matter, nitrogen, and gross energy, blood lymphocyte percentage, immunoglobulin G concentration, fecal Escherichia coli and Lactobacillus counts as well as fecal NH₃ and H₂S emissions associated with the inclusion of SPE in the diet. Average daily feed intake, red blood cells and white blood cells concentration were not significantly (P > 0.05) affected by SPE supplementation in the diets. In conclusion, results indicate that dietary SPE supplementation can improve growth performance, digestibility and fecal microbiota, and decrease fecal gas emissions in growing pigs.     

Nutritive defaunation of the rumen in steers with subsequent refaunation using a cryopreserved monoculture of Entodinium caudatum

This study evaluated a technique for the nutritive defaunation of the rumen of cattle with subsequent single species refaunation using a cryopreserved monoculture of Entodinium caudatum (family Ophryoscolecidae). Four mature steers were nutritionally defaunated in two periods using two steers in each period. A diet containing (dry matter basis) 68% ground wheat grain, 7% wheat bran, 8% soybean oil and 17% wheat straw was used to decrease the pH of ruminal contents and to eliminate rumen ciliate protozoa. Protozoa‐free rumens were observed on day 8 and 9 in the first and second period, respectively, after the start of defaunation. A monoculture of E. caudatum (34/89/94) was transported from the Institute of Animal Physiology, Slovak Academy of Sciences in Ko?ice to the University of Kiel (Germany) in liquid nitrogen in October 1996. The inoculation was accomplished on day 15 in the second period by applying 30 ml culture medium with a monoculture of E. caudatum (34/89/94; average concentration of protozoal cells 2 650/ml) into the rumen of a defaunated steer via the ruminal fistula. The mono‐faunated steer was successfully inoculated with an average concentration of E. caudatum cells at 4.1 × 10³/ml (SD = 0.2) on day 2 after the inoculation.     

The comparative study digestion and metabolism of nitrogen and purine derivatives in male, Thai, Swamp buffalo and Thai, Brahman cattle

Studies on in vivo digestion, rates of passages, metabolism of nitrogen, urinary purine derivative excretion and blood metabolites were carried out in Thai Brahman cattle and Thai swamp buffaloes (16 months old). The animals were fed mixed diets based on pineapple (Ananas comusus) waste silage containing urea‐N (NPN) and true protein from a concentrate (TP). The Brahman cattle (310 ± 15 kg) were heavier than the swamp buffaloes (195 ± 9.4 kg) and had higher dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) intakes when compared on the basis of their metabolic body weight (BW^0.75), but these intakes did not differ significantly when the diets of each animal species were compared. The total tract, apparent digestibilities of dry matter (DM) and organic matter (OM) were not significantly different between the animal species when comparing the two types of diets. The NDF digestibility was significantly (P < 0.01) decreased in both animal species when fed the TP diet, but was significantly (P < 0.01) greater in cattle than in swamp buffaloes. The passage rate digesta k₁ (P < 0.01) and the passage rate digesta k₂ (through the caecum and proximal colon) (P < 0.03) were significantly slower, and the total mean retention time (TMRT) (P < 0.01) was significantly longer in swamp buffaloes when compared to Brahman cattle, but the transit time (TT) showed no difference (P = 0.07) between the animal species or the diets. The N intakes were not different in both animal species and diets, but urine‐N was greater (P < 0.05) in Brahman cattle than that in swamp buffaloes. Urine N and digestibility of N were significantly (P < 0.04) higher in animals fed the NPN diet than those fed the TP diet. Urinary purine derivatives (PD) and the creatinine (Cr) excretion of swamp buffaloes were significantly (P < 0.01) lower than those in Brahman cattle. Plasma urea‐N (BUN) concentration was significantly (P < 0.01) higher in swamp buffaloes than that in Brahman cattle, but plasma glucose and insulin concentrations were significantly (P < 0.01) higher in Brahman cattle than in swamp buffaloes. The concentrations of non‐esterified fatty acids (NEFA) were not significantly (P > 0.05) different in animals fed different diets. The present study demonstrated that Brahman cattle were better in fiber digestibility than swamp buffaloes at utilizing pineapple waste silage with both N sources.     

Effects of 2-methylbutyrate on Daily Gain,Dietary Nutrient Digestion and Methane Emissions in Simmental Cattle

The objective of this study was to evaluate the effects of 2-methylbutyrate on daily gain,dietary nutrient digestion and methane emissions in Simmental cattle.Thirty-six Simmental cattle (12-month-old) consuming a corn straw diet were divided randomly into four groups (control group,experimental groups 1,2 and 3) and supplemented with four levels of 2-methylbutyrate as 0,1.0,2.0 and 3.0 g/(kg·BW),respectively.Dietary nutrient digestibilities,average daily gain and methane emissions were determined.The results showed that OM digestibilities of the cattles in experimental group 2 and 3,CP digestibilities of the cattles in experimental groups 2 were significantly higher than that in control group (P<0.05).NFE digestibilities were not affected by adding 2-methylbutyrate (P>0.05).NDF digestibilities of the cattles in experimental group 2 were significantly higher than that in control group and experimental group 1 (P<0.05),while their ADF digestibility were significantly higher than that in control and other experimental groups (P<0.05).Compared with control group,the average daily gains of cattles increased significantly in experimental groups 2 and 3 (P<0.05),the dry matter intakes of cattles decreased significantly in experimental group 2 (P<0.05),and the feed gain ratio decreased significantly in experimental groups 2 and 3 (P<0.05).In addition,the methane emissions were decreased significantly in experimental groups 2 and 3 (P<0.05).The results indicated that the average daily gain,nutrient digestion could be improved,and methane emissions could be restrained by supplementing 2-methylbutyrate in Simmental beef cattle,the optimal dose of 2-methylbutyrate supplementation was 2.0 g/(kg·BW).     

去盲肠和未去盲肠公鸡测定饲料氨基酸消化率的比较研究

应用Sibbald“TME”方法,比较了去盲肠和未去盲肠公鸡对饲料氨基酸的消化率。试验测定了10种饲料的去盲肠和未去盲肠公鸡的氨基酸消化率。结果表明,未去盲肠鸡对10种饲料的氨基酸表观和真消化率均高于去盲肠鸡。轻度受热鱼粉、重度受热鱼粉、脱毒棉籽饼、未脱毒棉籽饼和豆饼的表观氨基酸消化率在去盲肠鸡和未去盲肠鸡之间存在显著差异(P<0.05),未受热鱼粉和芝麻饼的表观氨基酸消化率在去盲肠鸡和未去盲肠鸡之间不存在显著差异(P>0.05)。轻度受热鱼粉、重度受热鱼粉、豆饼的真氨基酸消化率在去盲肠鸡和未去盲肠鸡之间存在显著差异(P<0.05);未受热鱼粉、脱毒棉籽饼、未脱毒棉籽饼和芝麻粕的真氨基酸消化率在去盲肠鸡和未去盲肠鸡之间不存在显著差异(P>0.05)。去盲肠鸡内源氨基酸排出量显著高于未去盲肠鸡(P>0.05)。微生物对未消化食糜中的肽类、氨基酸具有降解作用。     

Apparent digestibility of nitrogen and amino acids in protein feedstuffs by growing pigs

Eight digestion trials were conducted with pigs fitted with ileal T-cannulas to determine the apparent digestibilities of N and amino acids in common protein feedstuffs. Trial-to-trial variation was minimal as determined by the variation in digestibilities for soybean meal, which was evaluated in each trial. Apparent digestibilities varied widely; ileal N digestibility ranged from 88 to 63%, and ileal lysine digestibility ranged from 93 to 40%. In general, ring-dried blood meal, corn gluten meal, Menhaden fish meal, poultry-by-product meal and extruded whole soybeans were the most digestible, followed by canola meal, sunflower meal, peanut meal and meat and bone meal. Cottonseed meal and feather meal were the least digestible. Mean values for each feedstuff agree well with published data. Variation in digestibilities among samples of the same feedstuff was greater for the meat and bone meals. Regression of ileal essential amino acid digestibilities on ileal and fecal N digestibility indicated that amino acid digestibilities can be predicted more precisely from ileal N digestibility than from fecal N digestibility. However, neither ileal nor fecal N digestibility could be used with a high degree of certainty to predict ileal amino acid digestibilities.     

Determination of in vitro digestibility of forage species used in ruminant feeding

Within the evaluation of the quality of forage resources, the main parameter that defines it is the digestibility of dry matter, which together with the amount of neutral and acidic detergent fibers and crude protein constitutes the basic information to assess forages which are supplied in the diet of the cattle. This research was carried out at the University of Los Llanos (Villavicencio, Colombia), and its objective was to determine the digestibility of three forages in cattle through three different in vitro techniques: inoculation with ruminal fluid and with feces and enzymatic digestibility technique, making the comparison with the in situ technique in order to validate the techniques and equipment that are being used for these procedures. The following species were evaluated: Pennisetum purpureum (PP), Tithonia diversifolia (TD), and Bauhinia variegata (BV), assessing the curve and rate of degradation of dry matter (DM), neutral detergent fiber (NDF), and total protein (TP) (0 to 72 h). A design of repeated measures was used, under which the analysis of variance was carried out to determine the ranges of deviation between the techniques and thus establish the trend of the data; the variables evaluated were the DM, NDF, and TP digestibilities of the three forages using the four techniques (three in vitro and one in situ). After verifying the differences between the variances of the digestibilities and checking the sphericity assumption with the Mauchly test, multiple comparisons were made with the Bonferroni test with a significance of 5%. The digestibility of DM, NDF, and TP varied between 38.62 and 44.22, 54.18 and 66.97, and 47.54 and 57.05%; 49.07 and 70.70, 72.52 and 75.44, and 62.61 and 74.02%; 29.93 and 34.84, 26.21 and 70.88, and 25.67 and 50.60% respectively in forages PP, TD, and BV, depending on the technique used for their estimation. Despite finding statistically significant differences between several of the comparisons made in the digestibility techniques, a high coefficient of determination and a high correlation between the in vitro estimations with respect to the in situ estimation were found; therefore, it is possible to use these techniques routinely thus avoiding the need to have cattle with fistulae to perform digestibility tests, with enzymatic digestibility technique being the most practical one.