In vitro metabolism of tyrosine by rumen bacteria, protozoa and their mixture

An anaerobic in vitro study of tyrosine (Tyr) metabolism by rumen bacteria (B), protozoa (P) and their mixture (BP) was conducted using an HPLC analytical method to obtain some basic and systematic information on aromatic amino acid metabolism in the rumen. Most of the Tyr (> 96%) disappeared after 12 h incubation in B and BP, but only 58% in P. Tyr was converted mainly to p‐hydroxyphenylacetic acid (HPA) in all microbial suspensions. About 45% of disappeared Tyr in B and P, and about 35% in BP were converted to HPA. An appreciable amount of phenylalanine (Phe), 13 and 3% of disappeared Tyr, and a small amount of tryptophan (Trp), 8 and 1% of disappeared Tyr, were also produced from Tyr by rumen bacteria and protozoa, respectively. Small amounts of p‐hydroxyphenylpyruvic acid (about 4 and 6% of disappeared Tyr) were produced from Tyr in B and P, respectively. A moderately large amount of phenylacetic acid (14% of disappeared Tyr) was produced from Tyr in P which was 1.9 times higher than that in B. Phenylpropionic acid and p‐hydroxybenzoic acid were produced only in B and BP. It was concluded that the Tyr degradation ability of rumen bacteria was about 1.5 times higher than that of rumen protozoa. Degraded Tyr mainly produces HPA and then two other aromatic amino acids, Phe and Trp, which are considered essential amino acids for ruminants. Therefore, it is speculated that the requirement for Phe and Trp in ruminants may be partially fulfilled if Tyr is sufficiently supplied in rations.     

A quantitative study on arginine catabolism by mixed ruminal bacteria,protozoa and their mixture in vitro

The catabolism of arginine (Arg) by mixed rumen bacteria (B), mixed rumen protozoa (P), and their mixture (BP) was quantitatively investigated in an in vitro system in order to confirm the metabolic pathway of Arg and provide basic information for enzymatic and molecular studies as well as an understanding of the quantitative distribution of metabolites. Rumen microbial suspensions (B, P, and BP) collected from fistulated goats were anaerobically incubated with or without 1 mmol/L Arg at 39°C for 12 h. Arg and other related compounds such as citrulline (Cit), ornithine (Orn), proline (Pro) and 5‐aminovaleric acid (5AV) in both supernatant and hydrolyzates of B, P, and BP suspensions were analyzed by HPLC. The metabolic pathways of Arg in mixed rumen bacteria and mixed rumen protozoa were considered to be as follows: rumen bacteria, Arg → Cit → Orn → Pro → 5AV → VFAs + NH₃; rumen protozoa, Arg → Cit → Orn → Pro → 5AV. The disappearance of Arg (1 mmol/L) was approximately 52.9 and 88.2% in B, 33.9 and 55.6% in P, and 52.8 and 85.2% in BP during 6 and 12 h incubations, respectively. When expressed in units of ‘per gram (g) of microbial nitrogen (MN)’, the net degradation rate of Arg in BP (50.3 µmol/g MN/h) was approximately 46% lower than that of B during a 12 h incubation period. The presence of protozoa tended to inhibit the production of Orn from Cit and the production of 5AV from Pro which were thought to be rate‐limiting steps of Arg metabolism in rumen microorganisms. As a result, protozoa appeared to have a saving effect on Arg metabolism, that is, protozoa protected Arg from wasteful exhaustion in the rumen.     

Quantitative studies of the in vitro production of pipecolic acid by rumen protozoa and its degradation by rumen bacteria

An in vitro study was conducted to quantitatively investigate the metabolism of pipecolic acid (Pip), a neuromodulator, by mixed rumen bacteria (B), mixed rumen protozoa (P), a combination of B and P (BP), species‐enriched rumen protozoal suspension (Polyplastron sp., Diploplastron sp., entodinia and Entodinium caudatum) and pure cultures of several isolates of rumen bacteria (Prevetolla bryantii, Prevetolla albensis, Streptococcus bovis, Veillonella parvula, Megasphaera elsdenii and Ruminococcus albus). Only P produced Pip from L‐lysine (1.0 mmol/L L‐Lys) at a rate of 83.5 ± 1.6 µmol/L/h and even in BP, Pip was produced from L‐Lys by P and increased at a rate of 31.2 ± 3.8 µmol/L/h. Pip production by P was highest when the substrate (L‐Lys) concentration was 6 mmol/L and then the rate was 580 ± 36 µmol/L/h. Pipecolic acid production by P suspension enriched with different species of protozoa showed that Polyplastron sp. had the highest Pip production rate of 0.907 ± 0.092 µmol/L/mg protozoal protein per h, and Diploplastron sp. had the lowest rate of 0.55 ± 0.13 µmol/L/mg protozoal protein per h. The addition of D‐Lys (1.0 mmol/L) as a substrate to the P suspension revealed that P were also able to produce Pip from D‐Lys, though at a lower rate (1/3) compared with L‐Lys (1.0 mmol/L), suggesting the presence of epimerases in P. It was confirmed that B were unable to produce Pip from L‐ or D‐Lys. Only B degraded Pip (1.0 mmol/L) after a lag phase at a rate of 56.0 ± 1.5 µmol/L/h. The B suspension was able to degrade D‐Lys, though the products were not identified. Pip degradation by pure culture of some species of rumen bacteria showed that P. bryantii and R. albus had the highest rate followed by P. albensis, S. bovis and M. elsdenii with a low rate of Pip degradation. Veillonella parvula showed no ability to degrade Pip. The results suggest that a fairly large proportion of rumen‐produced Pip is likely to be absorbed by the host animal before degradation by rumen bacteria.     

日粮酪氨酸、苯丙氨酸、色氨酸水平和比例对泰和乌骨鸡生产性能及组织黑色素含量的影响

本试验旨在研究日粮酪氨酸、苯丙氨酸和色氨酸供给水平和比例对泰和乌骨鸡生产性能和组织黑色素含量的影响.选用612只1日龄泰和乌骨鸡,随机分成17个处理,每个处理设3个重复,每个重复12只鸡(公母各占1/2),饲养至4周龄.采用三因素二次回归正交组合设计试验方法,建立日粮三种氨基酸水平与泰和乌骨鸡日增重和组织黑色素含量的二次回归数学模型,得出0～4周龄泰和乌骨鸡分别取得最大日增重和组织黑色素含量时日粮三种氨基酸适宜供给量和比例模式.结果表明,日粮酪氨酸,苯丙氨酸和色氨酸供给水平和比例显著影响泰和乌骨鸡日增重和胸肌、腿肌黑色素含量(P<0.01),且泰和乌骨鸡取得最大日增重和组织黑色素含量时日粮三种氨基酸最适水平和比例模式各不相同.当日粮氨基酸含量分别为酪氨酸0.79%、苯丙氨酸1.06%和色氨酸0.13%,三者比例模式为Tyr:Phe:Trp=85:113:14(相对于日粮Lys含量的比值,Lys定为100)时,可取得最大日增重5.81 g/d;而当日粮三种氨基酸含量分别为酪氨酸0.81%、苯丙氨酸1.14%和色氨酸0.13%时,胸肌黑色素含量可取得最大值3.73%,三者最佳比例模式为Tyr:Phe:Trp=87:121:14.因此,通过调节日粮酪氨酸、苯丙氨酸和色氨酸供给水平和比例可改善泰和乌骨鸡生产性能以及体内黑色素的沉积.     

Biosynthesis of arginine from citrulline and related compounds by mixed ruminal bacteria, protozoa and their mixture in vitro

Biosynthesis of arginine (Arg) from citrulline (Cit), ornithine (Orn), proline (Pro), and 5-aminovaleric acid (5AV) by mixed rumen bacteria (B), protozoa (P), and their mixture (BP) was quantitatively investigated in an in vitro system from the standpoint of protein nutrition in ruminants. Rumen microorganisms, collected from ruminally fistulated goats, were anaerobically incubated with or without 1 mmol/L each of substrates at 39°C for 12 h. Arginine and other related compounds, produced in both supernatants and acid-hydrolyzates of microorganisms in B, P, and BP suspensions, were analyzed by high-performance liquid chromatography. Arginine production from Cit in BP, when expressed with a unit of 'μmol/g microbial nitrogen', was approximately 70% and 94% higher than that in B and P, respectively, in a 12-h incubation period. In the case of Orn, the values were approximately 30% and 75%. Both rumen bacteria and protozoa could produce Cit and Orn from Pro, so it is assumed that they can produce Arg from Pro. Rumen protozoa were unable to degrade 5AV and it was the final product in the metabolism of Cit, Orn and Pro in P suspension. A trace amount of Orn and Pro produced from 5AV in B and BP suspensions indicated that the reversible reaction of 5AV formation was performed only by rumen bacteria. This is the first quantitative report on Arg biosynthesis from its precursors by rumen microorganisms.     

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.     

Oral and intravenous l‐[1‐13C]phenylalanine delivery measure similar rates of elimination when gastric emptying and splanchnic extraction are accounted for in adult mixed hounds1–4

There are few reported estimates of amino acid (AA) kinetics in adult mammals and none exist in adult dogs. The study objectives were to evaluate the use of oral isotope delivery in contrast to the more commonly used intravenous (IV) delivery to estimate AA kinetics in adult dogs and to estimate splanchnic extraction and gastric emptying using a commonly accepted mathematical model. Dogs received 25 × 1/2‐hourly meals (13 g/kg BW/day) and either an oral or IV bolus of l‐ [1‐¹³C]Phe (12 mg/kg BW). Blood samples were taken immediately before each feeding. Concentrations of plasma Phe were measured using liquid chromatography‐tandem mass spectrometry. There were no differences in baseline plasma Phe concentrations (34 μm ± 0.61), Phe distribution volume, Phe pool size and rate constants between dogs when the tracer was administered IV or orally (p > 0.25). Decay curve for plasma l ‐[1‐¹³C]Phe differed between IV and oral dosing protocols with IV dosing fit best using a two‐compartment model. Phe disappeared from plasma at a mean rate of 2.8%/min. Estimates of gastric emptying and splanchnic extraction did not differ based on oral or IV tracer dosing when the decay curves were fit with the two‐compartment model (p > 0.40). The half‐life for gastric emptying was 18 min, and first‐pass Phe extraction by the splanchnic bed was 24% of the dietary Phe. These results suggest that oral isotope dosing can be used as an alternative to IV isotope dosing in studies that utilize a primed, constant dosing approach to measure protein and amino acid kinetics.     

Comparative effects of individual amino acid excesses when added to a corn-soybean meal diet: effects on growth and dietary choice in the chick

Six experiments were conducted with 8-d-old crossbred chicks to evaluate the effects of 4% excesses of DL-methionine (Met), L-phenylalanine (Phe), L-tryptophan (Trp), L-lysine (Lys), L-histidine (His), L-threonine (Thr), L-isoleucine (Ile), L-arginine (Arg), L-valine (Val) or L-leucine (Leu) on growth or dietary "choice" (i.e., self-selection) when added to 23% protein corn-soybean meal (C-SBM) diets. Arginine and His were supplied as the free base and Lys as Lys X acetate to avoid acid-base problems. In the growth studies, weight gain was reduced 92, 79, 53, 50, 47, 31, 29, 15, 9, 4 and 0% by additions of 4% Met, Phe, Trp, His, Lys, Tyr, Thr, Ile, Arg, Val and Leu, respectively. Improvements (P less than .05) in weight gain, feed intake and gain/feed occurred by addition of 1% Arg to the C-SBM diet supplemented with 4% excess Phe or Tyr. Addition of 1% Arg to the C-SBM diet supplemented with 4% excesses of most of the other amino acids also tended to improve performance, although diets imbalanced with Lys, Val or Leu did not respond to supplemental Arg. Self-selection studies revealed that chicks preferred the C-SBM diet containing 4% excess Lys over diets containing 4% excesses of Met, Thr, Arg or Trp. Moreover, chicks preferred diets with 4% excess Met, Thr or Arg over those containing an equal excess of Trp. When given a choice between the C-SBM diet and this diet supplemented with 4% Leu, chicks consumed similar quantities of both diets.     

不同植物蛋白的日粮对山羊胃肠道食糜氨基酸和肽的影响

选择3只徐淮白山羊,采用4×3拉丁方设计研究不同植物性蛋白源日粮(A:豆粕、B:棉籽粕、C:菜籽粕、D:玉米酒糟)对瘤胃和十二指肠内氨基酸和肽的影响。结果表明:各处理组瘤胃内的游离氨基酸、肽氨基酸浓度分别为8.55、5.38、7.37和7.74mg/L和41.76、36.89、33.65、29.59mg/L;游离氨基酸组成以Glu、Pro所占比例相对较大,Gly、Thr、Leu和Phe所占比例相对较小。肽氨基酸组成以Asp、Glu、Ser、Pro、Val含量相对较高,而Arg、Phe含量相对较低。十二指肠食糜游离氨基酸、肽氨基酸浓度分别为48.71、32.26、35.72、51.23mg/L和11.28、8.54、9.95、12.54g、100gDM;其中游离氨基酸中以Tyr、Ala、Val、Leu、Phe含量相对较高,His、Cys含量相对较低。各组中总氨基酸含量以Ala、Val、Leu、Phe含量相对较高,His、Cys含量相对较低;进入十二指肠的菌体蛋白氨基酸含量,以豆粕组最高,进入十二指肠的饲料氨基酸含量,以玉米酒糟组最高。     

Muscle growth and plasma concentrations of amino acids, insulin-like growth factor-I, and insulin in growing pigs fed reduced-protein diets

Twenty barrows were used to determine if partial replacement of protein-bound AA with crystalline AA (CAA) reduces AA use for muscle tissue and whole-body growth. Barrows (44.2 +/- 1.3 kg of BW) were assigned to 4 diets in a randomized complete block design. Diets consisted of 16.1% CP with no CAA, and 12.8, 10.1, and 7.8% CP containing CAA. As the CP concentration decreased, CAA were gradually increased to meet requirements on a true ileal digestibility basis. Barrows were weighed on d 0 and 13. Blood samples were collected before the morning feeding on d 0, 6, and 12 (prefeeding), and 2 h after the morning feeding on d 13 (postfeeding). Pigs were euthanized on d 13, and liver and right LM were removed and weighed. The reduction in the dietary CP concentration linearly decreased (P < 0.01) ADG, G:F, LM weight, and the CP content of LM. Reducing the CP concentration decreased pre- and postfeeding plasma concentrations of IGF-I (linear, P < 0.01) and insulin (linear, P < 0.10). The reduction in the dietary CP concentration increased prefeeding plasma concentrations of Ala, Gln, Gly, and total AA but decreased Arg, Asn, His, Ile, Phe, Trp, and Tyr (linear, P < 0.05). Plasma concentration of total indispensable AA decreased initially and increased thereafter as the dietary CP concentration decreased from 16.1 to 7.8% (quadratic, P < 0.01). The reduction in the dietary CP concentration increased postfeeding plasma concentrations of Ala, Lys, Met (linear, P < 0.01), and Gly (linear, P = 0.073) and decreased Asn, Ser, Tyr, Arg, His, and Leu (linear, P < 0.05). Plasma concentrations of Ile, Phe, Thr, Trp, and Val decreased initially and increased thereafter as the dietary CP concentration decreased from 16.1 to 7.8% (quadratic, P < 0.05). In muscle tissue, concentrations of free Ala, Asp, Glu, Gln, Gly, and Lys increased (linear, P < 0.05) as the dietary CP concentration decreased. Concentrations of free His, Ile, Phe, Thr, Trp, and Val in muscle tissue decreased initially and increased thereafter as the dietary CP concentration decreased from 16.1 to 7.8% (quadratic, P < 0.05). In summary, the reduction in the dietary protein-bound AA decreased whole-body and LM growth, altered the free AA pool profile in muscle tissue, and decreased plasma insulin and IGF-I. As the replacement of protein-bound AA with CAA increased, 1) free Ala and Gln in muscle tissue increased, indicating an increase of muscle tissue protein breakdown; and 2) utilization of indispensable AA in muscle tissue decreased.     

Performance and nitrogen metabolism of calves fed conventionally or following an enhanced-growth feeding program during the preweaning period

Thirty-seven Holstein and seven crossbred female calves (16.1 ± 4.60 days, and an initial BW of 36.5 ± 3.19) were used to study the effects of conventional (CF) vs enhanced-growth feeding programs (EF) on performance, plasma amino acid (AA) concentrations, and rumen microbial development. After 1 week of adaptation to milk replacer (MR), the CF calves received 4 l/day of MR at 12.5% DM throughout the preweaning period, and the EF calves were offered MR at 18% DM: 6 l/day from 1 to 6 days, 8 l/day from 7 to 26 days, and 4 l/day from 27 days to weaning day (38 days). Calf starter and water were offered ad libitum throughout the study (87 days). Calves fed EF were heavier (P < 0.05) than CF calves at the end of the study (111.7 vs 102.6 ± 1.72 kg, respectively). Until the 27 days, average daily gain (ADG) was greater (P < 0.001) for EF than for CF calves (1.00 vs 0.49 ± 0.061 kg/day, respectively), but it was lower (P < 0.001) from days 27 to 45 of the study (0.32 vs 0.71 ± 0.061 kg/day, respectively), coinciding with the days around weaning. Starter intake was greater (P < 0.001) for CF than for EF calves during the first 45 days of the study (0.60 vs 0.27 ± 0.061 kg/day, respectively) but similar afterwards. As a consequence, EF treatment may have delayed rumen function as suggested by total daily purine derivatives urinary excretion (49.52 vs 33.27 ± 3.095 mmol/day, in CF and EF calves, respectively). Linear regression analyses showed a positive relationship between plasma Trp and Phe concentrations and ADG, and a negative relationship between these two AA and plasma urea concentrations, suggesting that Trp and Phe could be limiting growth in calves fed conventional feeding programs.     

Study on the bacterial community structure and fermentation characteristics of fresh and ensiled paper mulberry

Two experiments were conducted to investigate the bacterial community of fresh and ensiled paper mulberry prepared with or without lactic acid bacteria (LAB) inoculants in South China. In Experiment 1, the bacterial community, chemical composition, and fermentation products of paper mulberry were analyzed. The results showed that fresh paper mulberry had high crude protein content, buffering capacity value, and amounts of uncultured bacteria. Ensiled paper mulberry showed poor fermentation with high pH value, ammonia–N content, and butyric acid content. In addition, Enterobacter was the dominant genus in silage, followed by Lactobacillus and Enterococcus. Water-soluble carbohydrates, ammonia–N, propionic acid, pH, and lactic acid (LA) were the main factors affecting bacterial community of silage. In Experiment 2, the BP17 (Lactobacillus plantarum) from natural fermented paper mulberry silage and two commercial inoculants (Silage-help [SH] and Chikuso-1 [CH]) were used as additives. Compared with other treatments, BP17 inoculant decreased (p < 0.05) pH and ammonia–N content and increased (p < 0.05) LA content of silage. Inoculation of BP17 also increased the dominance of desirable Lactobacillus and inhibited the growth of harmful bacteria in silage. These results confirmed that paper mulberry could be ensiled and epiphytic LAB inoculant can improve its fermentation quality.     

Phenylalanine requirement of the lactating sow

Six mature Yorkshire X Landrace sows were randomly assigned to a 6 X 6 Latin-square experiment on d 3 of lactation to determine the phenylalanine (Phe) requirement in the presence of excess tyrosine (Tyr). A control diet of corn sugar, cornstarch, whey, L-glutamic acid, solka floc, soybean oil, amino acids, minerals and vitamins was supplemented with L-Phe to provide .175, .250, .325, .400, .475 and .550% Phe and .47% Tyr. Each diet was fed to a maximum of 5.5 kg/d within each of six 7-d periods. Sow milk yield and average pig weight gain decreased (cubic, P less than .01) with increasing time period. Feed intake and average pig weight gain were depressed (quadratic, P less than .05) on the lowest Phe diet, but milk yield was not significantly affected. Daily nitrogen (N) intake was depressed (quadratic, P less than .01) when sows consumed the .175% Phe diet, but percent fecal N was not affected. Percent urine N decreased (quadratic, P less than .001) and percent N retained (without milk) increased with increasing Phe to .288 and .296%, respectively. Daily secretion of milk N as a percentage of N intake was not affected by diet. Percent overall N balance (with milk) increased with increasing Phe to .307%. Urea N decreased with increasing dietary Phe in both plasma (linear, P less than .01) and urine (quadratic, P less than .001) to a breakpoint at .285% Phe. A sharp rise (quadratic, P less than .01) in plasma Phe occurred at .299% dietary Phe. Plasma Tyr increased (quadratic, P less than .05) as dietary Phe increased, but no clear inflection point was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)     

丙酸镁对西门塔尔牛尿嘌呤衍生物和微生物蛋白的影响

选用4头年龄3.5岁,体况良好,体重500kg的中国西门塔尔牛阉牛。采用4×4拉丁方设计,研究日粮添加丙酸镁(100g/d)、丙酸(87g/d)和氧化镁(24g/d)对尿嘌呤衍生物(PD)和微生物蛋白(MCP)的影响。结果表明:日粮中添加丙酸镁、丙酸和氧化镁后,丙酸镁组和丙酸组尿囊素、PD、微生物氮(MN)、MCP较对照组和氧化镁组显著提高(P<0.05),但丙酸镁组和丙酸组差异不显著(P>0.05)。日粮添加丙酸镁、丙酸和氧化镁对尿酸(uric acid)含量无显著影响(P>0.05)。日粮中添加丙酸镁和丙酸提高了尿囊素含量和PD、MN和MCP产量,但处理对尿酸没有影响。     

Meat goat diet supplementation with crude glycerine: Ruminal fermentation metabolism,blood chemistry profile,animal performance and carcass traits

The objective of this experiment was to determine the effects of feeding varying levels of crude glycerine (CG) on dry matter intake (DMI), animal performance, carcass traits and rumen volatile fatty acids (VFA) concentration in meat goats. Twenty-four intact male Boer goats (23.9 ± 1.0 kg initial BW and 4–5 months of age) were randomly assigned to one of four experimental diets (n = 6) containing 30% bermudagrass hay plus 70% concentrate mix with 0, 5, 10 or 15% CG in the diet on an as-fed basis, substituted for the corn portion of the concentrate. Feed offered and refusals were monitored daily for 84 days. Goats were weighed at 28-days interval. Blood and rumen samples were collected on day 84. At the end of the 84-days feeding period, goats were harvested, and carcass characteristics measured. Feed intake, average daily gain (ADG), gain-to-feed ratio (G:F), carcass traits and VFA concentrations were analysed as a completely randomized design. The CG did not influence animal body weight (BW) changes, ADG and G:F ratio but tended to (p = 0.06) decrease DMI. Molar per cent propionic acid increased linearly (p < 0.05) with increasing CG. The acetate: propionate (A:P) ratio decreased (p < 0.05) with increasing amounts of CG in the diet. The CG addition tended to increase (p = 0.09) the longissimus muscle (LM area) in meat goats. In conclusion, CG can replace corn in diet for growing meat goats when fed up to 15% of diet, improving ruminal propionate concentration, but decreasing A:P ratio without affecting animal performance and carcass traits.     

Effects of crystalline amino acid supplementation to the diet on odor from pig manure

The objective of this study was to determine the effects of specific crystalline AA supplementation to a diet on odor emission, odor intensity, odor hedonic tone, and ammonia emission from pig manure, and on manure characteristics (pH; ammonia N; total nitrogen; sulfurous, indolic, and phenolic compounds; and VFA concentrations). An experiment was conducted with growing pigs (n = 18) in a randomized complete block design, with 3 treatments in 6 blocks. Treatment groups were (1) a 15%-CP basal diet with 3 times the requirement of sulfur-containing AA (14.2 g/kg of diet, as-fed basis); (2) the basal diet with 2 times the requirement of Trp and Phe+Tyr (2.9 and 20.4 g/kg of diet, respectively, as-fed basis); and (3) the basal diet with AA supplementation to levels sufficient for maximum protein gain. Pigs with an initial BW of 41.2 +/- 0.8 kg were individually penned in partly slatted floor pens and offered a daily feed allowance of 2.8 times the maintenance requirement for NE (293 kJ/kg of BW(0.75)). Feed was mixed with water at 1:2.5 (wt/wt). Feces and urine of each pig was allowed to accumulate in separate manure pits under the slatted floor. After an adaptation period of 2 wk, and after cleaning the manure pits, manure was subsequently collected. In wk 5 of the collection period, separate samples were collected directly from each manure pit for odor, ammonia, and manure composition analyses. Air samples were analyzed for odor concentration and for hedonic tone and odor intensity above the odor detection threshold. Results showed that supplementing crystalline S-containing AA in surplus of the requirement increased odor emission (P < 0.001) and odor intensity (P < 0.05) and reduced odor hedonic tone (P < 0.05) from the air above the manure pits. Supplementing crystalline Trp, Tyr, and Phe in surplus of the recommended requirements did not affect odor emission, odor intensity, or odor hedonic tone. Regardless of dietary treatment, all pigs had similar performance levels. No differences were observed in ammonia emission from manure of pigs fed different levels of AA supplementation (P = 0.20). To reduce odor from pig manure, dietary S-containing AA should be minimized to just meet the recommended requirements.     

Effect of Adding Different Mannan Oligosaccharide to Diets with Different Concentrate to Forage Ratios on Rumen Degradability of Fiber in Sheep

To investigate the effect of adding mannan oligosaccharide to diets with different concentrate to forage ratios on the degradability of neutral detergent fiber (NDF) and acid detergent fiber(ADF) in rumen of sheep by nylon bags technique,6 wethers (White Suffolk♂×Small-tailed Han sheep♀) installed permanent rumen fistula were used for offering rumen fluid.The 4×6 two-factor experimental design was chosen and the two factors were the ratio of concentrate to forage (A1(20:80),A2(30:70),A3(40:60),A4(50:50)) and the dose of mannan oligosaccharide (B1 (0),B2 (0.4%),B3 (0.8%),B4 (1.2%),B5 (1.6%),B6 (2.0%)).The results showed that the rumen degradability of NDF and ADF in different times,degradation parameters and effective degradability were influenced by the factor A significantly (P< 0.05).The rumen degradability of NDF and ADF in each time of group A1 were higher than group A3 and A4 (P< 0.05).Expect for 24 h,the rumen degradability of ADF were influenced significantly by the factor B,and the rumen degradability of ADF in group B5 was higher than group B1 and B2 (P< 0.05).The rumen effective degradability of NDF in group A3 was significantly higher than groups A1 and A2 (P< 0.05), and a little higher than group A4 (P >0.05),which showed that the rumen effective degradability of NDF and ADF were higher when the ratio of concentrate to forage was 40:60.     

Efficiency of utilisation of different diets with contrasting forages and concentrate when fed to sheep in a discontinuous feeding pattern

The effects of feeding different levels of forages and concentrate, in a discontinuous feeding pattern, on the efficiency of feed utilisation and rumen function were studied using rumen fistulated sheep. Experiment 1 was a 4 × 4 latin square design to determine the whole tract digestibility and rumen characteristics of diets comprising 15% (C15), 25% (C25), 35% (C35) and 45% (C45) concentrate (energy-dense dairy pellets) with the rest of the diet being a combination of fresh short rotation ryegrass (Lolium mutiforum) and conserved (lucerne hay and maize silage) forages. In Experiment 2, the rumen degradation characteristics of feed ingredients were determined using the nylon bag technique. Daily dry matter intake (either expressed as g/kg LW or g/kg W ^0.75) was 10% lower (p = 0.03) for the C15 diet compared with C25, C35 and C45 diets. The apparent in vivo digestibility of dry matter (DM) for C15 diet was 4% higher (p = 0.04) than the C35 and C45 diets which may be attributed to the high quality of the forage (ryegrass) used.Fibre digestibility decreased as proportion of concentrate in the diet increased. However, this was unlikely due to changes in the rumen fermentation pattern, as neither pH (6.1 ± 0.23) nor ammonia concentration (24.4 ± 6 mg/dl), were different (p > 0.05) among diets. Instead, the lower fibre digestion was most likely the result of different type and proportion of fibre among diets, as total rumen degradability and rate of fibre degradation in the rumen were higher (p = 0.001) for ryegrass than for other feedstuffs. There was no significant difference in total nitrogen balance and urinary allantoin excretion among diets, which indicated similar total microbial protein synthesis (MPS). The asynchrony observed, for N and energy availability in the rumen for different diets using Sinclair et al. [Sinclair, L.A., Garnsworthy, P.C., Newbold, J.R., Buttery, P.J., 1993. Effect of synchronizing the rate of dietary energy and nitrogen release on rumen fermentation and microbial protein synthesis in sheep. J. Agric. Sci. 120, 251–263] equation, was due to the feeding pattern used in this study leading to excess of N in relation to total organic matter digested in the rumen. In conclusion, feeding concentrates in the diets as PMR with conserved forages in a discontinuous feeding pattern may be valuable to develop feeding strategies in a pasture based system for high producing dairy cows without affecting the rumen system.     

Influence of fibrolytic enzymes in total mixed ration containing urea-molasses-treated sugarcane bagasse on the performance of lactating Holstein–Friesian crossbred cows

The aim of this study was to determine the effect of different levels of fibrolytic enzyme on nutrient utilization and milk production in dairy cows. Four multiparous early-to-mid-lactation Holstein–Friesian crossbred cows were randomly allocated in a 4 × 4 Latin square design. Cows were fed a balanced total mixed ration (TMR) on a dry matter (DM) basis containing 0, 1.2, 2.4, and 3.6 g/kg DM of fibrolytic enzyme in TMR, where the TMR comprises 60% concentrate supplemented with a fibrolytic enzyme at 0, 2, 4, and 6 g/kg DM of concentrate, and 40% urea-molasses-treated sugarcane bagasse (UMSB) was used as a roughage source. Fibrolytic enzyme supplementation in TMR containing UMSB did not affect dry matter intake (DMI) of dairy cows (p > 0.05). There was a quadratic effect of fibrolytic enzyme levels on the digestibility of DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) (p < 0.05), and the maximal response was reached at 1.2–2.4 g/kg DM of fibrolytic enzyme added in the TMR. Furthermore, 3.5% fat-corrected milk, milk fat, total volatile fatty acids, and propionic acid were greater in a cow fed with 1.2–2.4 g/kg DM of fibrolytic enzyme, resulting in a lower ratio of acetic acid to propionic acid (p < 0.05). In conclusion, adding a fibrolytic enzyme in TMR containing UMSB improved nutrient utilization, rumen fermentation, and milk production of lactating dairy cows.