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1.
Eight pea genotypes characterized for their major protein fractions were used to investigate the effect of seed protein composition variability on protein digestibility in poultry. These genotypes of various pea types, were also variable in other seed components. They showed variations in their carbohydrate (insoluble fibre compounds, soluble fibre, soluble carbohydrates) and trypsin inhibitor (TI) contents. To exclude the effect of tannins and of particle size, the seeds were dehulled and micro-ground. They were incorporated as the only protein source in isoproteinaceous diets with similar metabolisable energy content and fed to cecectomized chickens. The average amino acid digestibility (apparent and true) and endogenous amino acid excretion were related with pea diet characteristics (protein composition, carbohydrate composition and TI activity). This allowed to precise which of the diet characteristics affect protein digestibility and endogenous excretion. Average apparent digestibility of amino acids was negatively correlated with insoluble fibre components (R = − 0.71 to − 0.72; p < 0.05) and TI activity (R = − 0.93; p < 0.001). Average endogenous losses of amino acids were positively correlated with soluble carbohydrate content (R = 0.77; p < 0.05) and TI activity (R = 0.84; p < 0.01). Average true digestibility of amino acids was positively correlated with the PA2 albumin level (R = 0.71; p < 0.05), and negatively with the legumin level (R = − 0.72; p < 0.05). Resistant peptides extracted from chicken excreta were analysed through electrophoresis and identified by immunodetection. Intensity of detected resistant peptides showed variation among genotypes. However, for the 8 pea genotypes, the pea proteins, which persisted at the end of the digestive tract, were mainly albumin PA1b and lectin. Other minor peptides were also detected: vicilin, albumin PA2 and legumin peptides which migrated at the same level as β-subunits.  相似文献   

2.
A digestibility trial on piglets was conducted to study the effect of an enzyme complex derived from Trichoderma longibrachiatum (Roxazyme G2) supplemented to a rye-based diet on apparent ileal digestibility of amino acids and NSP-constituting sugars. Enzyme supplementation at 200 mg kg− 1 increased (P < 0.05) the digestibility of total amino acids from 67.1 to 70.8. As the dietary concentration of Roxazyme G2 increased from 0 to 100 mg/kg, the ileal digestibility of the NSP constituents gradually increased. No further increase was observed with the supplementation level of 200 mg/kg. The improvement in the digestibility of arabinose + xylose (685%, P < 0.05) was much higher than that of the remaining sugars (110%, P < 0.05). The apparent ileal digestibility of galactose was positively influenced by Roxazyme G2 but it remained negative in all dietary treatments, presumably due to the high concentration of galactose in endogenous secretions. It is concluded that Roxazyme G2 effectively degrades non-starch polysaccharides in upper digestive tract and marginally improves amino acid availability in young pigs.  相似文献   

3.
Two digestibility experiments were carried out to comparatively measure true phosphorus (P) digestibility and the faecal endogenous P loss associated with soybean meal (SBM) and wheat middling meal (WM) for growing pigs by the simple linear regression analysis technique and the substitution method. Eight barrows, with an average initial body weight 21 kg, were randomly divided into two groups of four pigs with each group being fed four test diets according to a 4 × 4 Latin square design. Eight maize starch-based diets containing four levels (on dry matter basis) of P (0.20, 0.24, 0.36 and 0.42%) and P (0.181, 0.26, 0.36, and 0.43%) were formulated from SBM and WM as a sole source of P, respectively. Chromic oxide (0.30%) was used as a digestibility marker. Each experimental period comprised 8 d with a 4-d adaptation and a 4-d collection of faecal samples. Levels of the assay ingredient substitutions had no effects (P > 0.05) on true P digestibility and the endogenous P loss associated with SBM and WM measured by the substitution method. There were no differences (P > 0.05) between the regression technique and the substitution method in measuring the true P digestibility (SBM: 49.4 ± 3.51 vs. 50.6 ± 2.4; WM: 63.7 ± 5.0 vs. 63.2 ± 5.4%) as well as the faecal endogenous P loss (SBM: 0.62 ± 0.10 vs. 0.71 ± 0.11; WM: 0.65 ± 0.16 vs. 0.70 ± 0.17 g/kg dry matter intake) for the growing pig. Thus, true P digestibility and the faecal endogenous P loss in feed ingredients for pigs may be measured by using the regression analysis technique and the substitution method.  相似文献   

4.
The influence of a dietary supplementation with Saccharomyces cerevisiae (SC) during the first and the second phase of lactation on dry matter (DM) intake, organic matter digestibility, milk yield and quality and haematological profile was evaluated in buffalo cows. Lactating buffaloes (n = 190), 118.7 days in milk (DIM), were randomly divided into Group C (control, n = 95) and Group T (fed diet supplemented with 98 billion CFU of S. cerevisiae, n = 95). Eight buffaloes for each group (Groups T1 and C1), 85.4 DIM, were used to study the in vivo digestibility and the haematological profile. No differences were found for DM intake (16.5 kg·day− 1) and haematological profile. The SC supplementation increased milk yield (7.9 ± 0.2 vs. 7.4 ± 0.2; P < 0.01) but did not affect milk fat and protein. SC supplementation increased OM digestibility, mainly, in the first phase of lactation (< 135 days), thus allowing a higher energy availability for milk yield and reduced fat mobilization.  相似文献   

5.
Ileal indigestible protein may be an important factor for the occurrence of post weaning diarrhoea in piglets. Depending on the quantity of indigested protein, an imbalance in the microbial community can occur, resulting in an overgrowth of pathogens. Diet viscosity may influence nutrient digestibility and substrate availability for microbial growth. Therefore, we examined the effect of dietary viscosity in piglet nutrition. Carboxymethylcellulose (CMC) was added as a model substance in order to increase diet viscosity. The effect of 1% supplemented CMC on nutrient digestibility, morphological and physiological parameters was measured in piglets 3 weeks post weaning at 26 days of age. The main effects of inclusion of CMC were:
– A 10% slower gastric emptying rate (P = 0.18).

– An increased protein hydrolysis in the gastric fraction, measured as increased nitrogen concentration in the liquid phase of gastric contents (26% in control vs. 34% in experimental group; P = 0.13).

– An increased production of the protein hydrolysing enzyme amino-peptidase from 359 U/g protein for the control diet to 516 U/g protein for the experimental diet (P < 0.01).

– A numerical increase in apparent ileal protein digestibility by 6% from 75.2% to 79.5% (P = 0.22) and a significant increase in faecal protein digestibility by 5% (P = 0.044).

These results indicate that an optimized diet viscosity might be one factor exerting a beneficial influence on protein digestibility. We hypothesize that the effect of diet viscosity on gastric emptying rate is the major factor.  相似文献   


6.
Value-added processing of cereals produces high-value fractions for food and bio-processing application and by-products that are used in animal nutrition to reduce feed costs. Wheat by-products contain arabinoxylans that might limit nutrient digestibility. Effects of xylanase supplementation (0 or 4375 U/kg feed) on energy digestibility were studied in a wheat control and by-product diets (30% millrun, middlings, shorts, screenings, and bran) in a 2 × 6 factorial arrangement. The wheat control diet was formulated to contain 3.34 Mcal digestible energy (DE)/kg and 2.8 g apparent digestible lysine/Mcal DE, and included 0.4% chromic oxide as a marker for digestibility. Twelve ileal-cannulated pigs (32.5 ± 2.5 kg) were each fed seven of 12 diets. Faeces and then digesta were each collected for 2 d, and diet digestibility values are reported. Wheat had higher ileal and total-tract energy digestibility than by-products (P < 0.01). Xylanase improved energy digestibilities for by-products (P < 0.001) but not for wheat. Among by-products, ileal energy digestibility was lowest for middlings (62%), then bran < screenings < millrun, and highest for shorts (66%). Xylanase improved (P < 0.05) ileal energy digestibility of millrun by 19% to 76%. Total-tract energy digestibility of millrun improved from 72 to 79% (similar to wheat) with xylanase (P < 0.05). In summary, xylanase improved energy digestibility in the selected wheat by-product diets, indicating that arabinoxylans in wheat by-products limit nutrient digestibility.  相似文献   

7.
The effect of bile extract on microbial gas formation and composition, production of volatile fatty acids (VFA) and methane and on reductive acetogenesis was studied in vitro. As substrates cellulose and potato starch in combination with graded levels of bile extract concentrations (0; 333; 666; 1333 mg/l) were incubated with a faecal suspension from pigs as microbial inoculum according to procedures of a modified “Hohenheim gas formation test” (HFT). Bile extract concentration of 1333 mg/l in the in vitro system reduced total gas production from cellulose significantly (p < 0.05) compared to incubation without bile extract. After 24 h of incubation, bile extract concentration of 1333 mg/l lead to a decrease in methane production from cellulose (p < 0.05) in comparison to incubation without bile extract. Increasing levels of bile extract reduced total production of VFA (p < 0.05) from cellulose. Furthermore, bile extract concentration of 1333 mg/l increased molar percentage of propionate from cellulose and starch after 24 h of incubation (p < 0.05). Bile extract concentration of 333 mg/l increased molar percentage of propionate from cellulose after 48 h of incubation (p < 0.05). The results may contribute to explain the differences in gas and methane production between the rumen and the hindgut of monogastric animals.  相似文献   

8.
This study was conducted to determine the effect of addition of essential amino acids (EAA) to low-protein diets on N balance in barrows. Thirty barrows (Duroc × Yorkshire) with an initial BW of 36 kg were fed 5 corn- and soybean meal-based diets containing 13.6 to 18.2% crude protein (CP) for 10 d in a randomized complete block design. The 18.2% CP diet was formulated without addition of EAA (Lys, Met or Thr). The other diets contained 13.6 to 16.5% CP and were supplemented with EAA to provide 0.83% true digestible lysine equal to that in the 18.2% CP diet. Fecal, urinary, and total N excretion as well as N retention (g/d) decreased with decreasing dietary CP level (P < 0.01). The apparent digestibility of N was almost the same for the 18.2 and 16.5 CP diets, but the value was 2% higher (P = 0.07) than that for the 13.6% CP diet. These findings indicate that, compared with the 18.2% CP diets, supplementation with three EAA to the lowest-protein diets (13.6 CP) is inadequate for maximum intestinal protein digestion, amino acid absorption, or tissue protein deposition in growing barrows.  相似文献   

9.
The objectives of this study were to determine the effects of microwave irradiation on ruminal degradability and intestinal digestibility of crude protein (CP) and to monitor the fate of true proteins of cottonseed meal (CSM) in the rumen. Duplicate nylon bags of untreated or irradiated CSM (microwave power of 800 W for 2, 4 and 6 min) were suspended in the rumen of four non-lactating Holstein cows for up to 48 h, and resulting data were fitted to non-linear degradation model to calculate degradation parameters of CP. Proteins of untreated and treated CSM bag residues were fractionated by gel electrophoresis. Intestinal digestibility of CP was measured using the mobile nylon bag technique. From in situ results, microwave irradiation decreased (P < 0.05) the water soluble fraction and degradation rate, but increased the potentially degradable fraction of CP. The effective degradability of CP decreased (P < 0.05) as processing period increased. Irradiation for 2 and 4 min increased (P < 0.05) intestinal digestibility of ruminally undegraded CP, but extending to 6 min lowered (P < 0.05) the beneficial effect that 4 min had on intestinal CP digestibility. Electrophoretic results indicated that globulin 9S in untreated CSM (whereas globulin 9S, globulin 5S and albumin 2S in microwave irradiated CSM) make the bulk of escaped protein. Based upon these results, microwave irradiation at a power of 800 W for 4 min had the greatest potential to increase digestible undegraded protein.  相似文献   

10.
A feeding trial was carried out for 90 days to asses the supplementing effect of tagasaste forage as a substitute for a concentrate supplement (wheat bran–noug seed cake (Gizotia abyssinica) mixture in 3:1 proportion) using 24 Menz male sheep (initial weight of 18.3 ± 1.6 kg). The sheep were fed on natural pasture hay as basal diet. The treatments were iso-nitrogenous supplements of 100% concentrate offered at 200 g DM/sheep/day (T1), 67% concentrate + 33% tagasaste (T2), 33% concentrate + 67% tagasaste (T3) and 100% tagasaste (T4). Digestibility tests of treatment diets were done for 10 days following the feeding trial using the same experimental animals. At the end of the experiment, carcass parameters were also evaluated. In situ degradability of feeds was determined using three rumen fistulated crossbred steers. Tagasaste forage contains more CP (215 g/kg), ADF (221 g/kg), ADL (69 g/kg); and less NDF (351 g/kg) compared to the concentrate. The concentrate had a high immediately soluble fraction (a), and a low insoluble but potential degradable matter (b), while tagasaste had a low a and higher b values and the overall potential degradability was 755, 702, and 586 g/kg, for tagasaste, concentrate and natural pasture hay respectively. Tagasaste forage had also shown higher rates of degradation (c) compared to the concentrate which might increase the total effective degradability. In the feeding trial the supplements made 26.8, 27.0, 28.3 and 29% of the total dry matter (DM) intake for T1, T2, T3, and T4, respectively. Increasing the inclusion of tagasaste forage significantly (P < 0.01) decreased the daily total DM intake of the basal diet and total metabolizable energy (ME), and increased the CP intake. The average weight gain of sheep did not show significant difference (P > 0.05), but had a decreasing trend, with 44.4, 41.4, 38.9 and 38.1 g/sheep for T1, T2, T3, and T4, respectively. The in vivo digestibility of DM and nutrients generally followed the order of T1 > T2 > T3 > T4. The dressing percentage of the carcass was 40.4% and all other parameters measured did not show significant variation due to treatment diets (P > 0.05). However, weight of liver, kidney and spleen was higher for sheep fed with higher tagasaste forage diet. The result of this study revealed that tagasaste can substitute wheat bran–noug seed cake concentrate mixture as a protein supplement. Options to increase the low ME and minimize the effect of the anti nutritional factors will improve nutrient digestibility in tagasaste forage and will enhance the overall efficiency of feed utilization.  相似文献   

11.
The relationship between passage rate of digesta (PRD) and apparent faecal dry matter digestibility (DMD) was investigated in five trials. In trial 1, 2, and 3, 36 weanling (16.9 ± 3.0 kg), 24 growing (51.3 ± 8.8 kg), and 23 finishing (104.8 ± 5.2 kg) barrows were housed in metabolic crates. The beginning and end of 5-day collection periods were marked by the addition of 0.5% indigo carmine to the feed for total faeces collection and PRD determination by observing the time required for the marker to appear. In trial 4 and 5, 21 gestating gilts (215.0 ± 15.0 kg), and 19 lactating sows were individually penned. Addition of 0.5% chromic oxide to the feed enabled indirect determination of DMD and PRD. The PRD, which ranged from 12 to 80 h, was positively correlated with DMD in weanling (R2 = 0.483, P < 0.001), growing (R2 = 0.425, P < 0.01), and finishing (R2 = 0.553, P < 0.001) pigs. Body weight and DMD were not significantly correlated in weanling (R2 = 0.001, P = 0.893), growing (R2 = 0.000, P = 0.995), or finishing (R2 = 0.092, P = 0.156) pigs. A positive correlation between PRD, which ranged from 27 to 102 h, and DMD occurred in gestating gilts (R2 = 0.231, P < 0.05), but not in lactating sows (R2 = 0.014, P = 0.633). The results indicate that longer retention times of digesta improve DMD in swine. Also the results indicate the importance of PRD as a potential independent variable in digestibility assessments.  相似文献   

12.
Phosphorus (P) from plant-derived feedstuffs is mainly in the form of phytic-P, which has a very low bioavailability in monogastric animals. The non-absorbed phytic-P may contribute to P pollution, reduce mineral bioavailability and might reduce protein digestibility. The aim of this study was to evaluate the effects of the recommended levels of Ronozyme® P CT 5000 (750 U/kg — RP) and Natuphos® 5000 (500 U/kg — Nat) on the ileal apparent digestibility of total P, phytates (Phy), calcium (Ca), total nitrogen (N), energy, and amino acids (AA) in 60-day-old ileo-rectal anastomosed pigs. In a double Latin square design they were fed ad libitum either a maize–rapeseed meal based diet or this diet supplemented with RP or with Nat. RP and Nat increased the digestibility of P by 148% and 162%, of Phy by 84% and 76%, and of Ca by 44% and 50%, respectively. The total N digestibility was increased by 4% with RP (P < 0.01) and by 1% with Nat. A numerically increase of the digestibility of most of the AA was observed for Nat and of all AA for RP. Threonine digestibility was significantly increased by RP (P < 0.05). The results of this study indicate that phytases are able to increase the availability of proteins.  相似文献   

13.
The effect of phytase and xylanase supplementation of a wheat-based pig diet on the ileal and total tract apparent digestibility of dietary components and minerals were studied in eight growing pigs fitted with a PVTC cannula in a randomized block design experiment. The diets (A and B) were similar in major ingredient composition and in nutrient content. In diet A, part of the limestone was replaced with di-calcium phosphate to increase the content of available phosphorus (P). Diet B was fed without or with supplementation with phytase (500 FTU/kg; diet BP), xylanase (4000 XU/kg; diet BX) and phytase + xylanase (500 FTU and 4000 XU/kg; diet BPX). There were no differences (P > 0.05) between diets in the ileal or total tract digestibility of organic matter (OM), NDF and crude protein (CP). The ileal and total tract digestibility for P and Ca differed (P < 0.05) between diets, while there were no treatment effects for Zn. The ileal and total tract digestibility for P and Ca was higher (P < 0.05) on diets BP and BPX than on the other diets. In conclusion, phytase improved the utilization of dietary P and Ca in a wheat-based diet, while xylanase had no additional benefits in terms of OM and CP digestibility or mineral utilization. Phytase had no effect on the digestibility of OM, CP or NDF.  相似文献   

14.
A 2 × 2 factorial arrangement was used to investigate the interaction between lactose level (170 vs. 275 g/kg) and enzyme supplementation (with or without Endo-1,3 (4)-β-glucanase) in barley based diets (250 g/kg) on piglet performance post weaning. Ninety six weaned piglets (24 days old, 6.5 kg live weight) were blocked on the basis of live weight and were assigned to one of 4 dietary treatments (n = 6) for 21 days. There was an interaction (P < 0.05) between lactose level and β-glucanase supplementation on average daily gain (ADG), food conversion ratio (FCR) and apparent digestibilities of dry matter (DMD), organic matter (OMD) and nitrogen (N). Pigs offered 170 g/kg lactose and β-glucanase supplementation had an improved FCR and ADG compared to the 170 g/kg lactose and unsupplemented barley. However, β-glucanase supplementation at 275 g/kg lactose had no effect on FCR and ADG compared to the 275 g/kg lactose and untreated barley. Pigs offered the diet containing the low level of lactose and β-glucanase supplementation increased (P < 0.05) DMD, OMD and N digestibility compared to the β-glucanase supplemented high lactose diet. However, there was no effect of lactose level in the unsupplemented diets. In conclusion, the inclusion of β-glucanase at the 170 g/kg lactose level improved ADG, FCR and diet digestibility. β-glucanase had a negative effect on FCR and ADG at the 275 g/kg lactose level.  相似文献   

15.
Eighteen Iberian barrows of 100 kg initial BW were used in a comparative slaughter experiment to investigate the effects of feeding level (FL; 0.70 and 0.95 × ad libitum) on growth, protein- and fat-deposition rates and body composition. They were fed on a diet supplying the optimum level of digestible ideal protein:ME ratio (4.82 g/MJ) and slaughtered at 150 kg BW. The apparent digestibility of DM, OM, total N and GE, and the ME:GE and ME:DE ratios were not affected by FL. The average daily gain increased with the increase in FL (691 and 918 g/day respectively). Neither the gain:feed (g/g DM) nor the gain:ME intake (g/MJ) ratios were significantly affected however. An energy cost of 59.9 kJ ME/g gain was calculated. The rate of whole-body protein deposition was not significantly altered by FL. On average it reached 80 g/day. The pigs fed at the lowest level exhibited lower fat deposition (P < 0.01) and total energy retention (P < 0.01) than those in the group subjected to only a slight feed restriction. The overall efficiency of utilization of ME for energy gain (ER:ME intake) remained at 0.363 on average, irrespective of the FL imposed. Relative proportions of energy retained as protein and fat were not statistically altered by changes in FL. Mean values for ERP:ER and ERF:ER were 0.100 and 0.903 respectively. No differences between treatments were observed in fat, ash, water or energy content of the whole-body (g/kg) at 150 kg empty BW, the mean values (n = 12) being 512 ± 8.5, 27.6 ± 0.63 and 353 ± 6.7 g/kg for fat, ash and water respectively and 22.90 ± 0.31 MJ/kg for energy. Nevertheless, the proportion of protein tended to decline with the increase in FL (111 vs 104; P = 0.069). At 150 kg the Iberian pigs contained more fat and energy and less ash and water than at 100 kg. Whilst the percentage of lean tissue decreased significantly (P < 0.05) and protein content in the carcass showed a strong tendency to decline in the pigs fed close to ad libitum (104 vs 96; P = 0.056), the proportions of fat, ash, water and energy remained constant at 564 ± 9.0, 22.2 ± 0.91, 312 ± 6.6 g/kg, and 24.82 ± 0.32 MJ/kg, respectively. It was concluded that a degree of feed restriction may result in a discernible improvement in carcass quality.  相似文献   

16.
The objective of this study was to study the effect of fibrolytic enzyme (FE) inclusion on nutrient digestibility and growth performance of Awassi lamb fed on a high concentrate diet. Thirty weaned Awassi lambs (initial body weight = 20.4 ± 3.0 kg) were fed a high concentrate diet (with or without the addition of FE (15 lambs/treatment)) for 60 d in a completely randomized design. The diet contained 17, 7, 58.5, 15, and 2.5% wheat straw, wheat bran, barley grain, soybean meal and minerals, respectively. Lambs were fed ad libitum twice daily at 08:00 and 15:00 h. Dry matter, OM, CP, and NDF intakes were all similar (P > 0.05) for lambs fed diet with or without the FE and averaged 1078, 941, 171, and 432 g/d, respectively. Metabolizable energy intake was also not affected (P > 0.05) by the enzyme supplementation and averaged 2.87 Mcal/d. Dry matter, OM, CP, and NDF digestibilities were all unaffected (P > 0.05) by the enzyme inclusion and averaged 64.8, 67, 65.7 and 60.4%. Final body weight, average daily gain, and feed to gain ratio were all unaffected (P > 0.05) by the FE inclusion and averaged 34.9 kg, 222 g/d, and 5.4, respectively. In summary, FE treatment of high concentrate diet for lambs had no effect on nutrient intake or any of the growth performance parameters. Therefore, supplementing such diets with FE for fatting Awassi lambs is not recommended.  相似文献   

17.
The hypothesis that increase in dietary phytin amplifies phytin binding to protein thereby reducing protein digestion, which is alleviated by phytase, was tested. A 2 × 2 factorial arrangement of dietary treatments was used to investigate the response of growing pigs to supplemental phytase (0, or 1200 units/kg) in low- or high-phytin P diets (2.2 or 3.9 g/kg). Eight crossbred barrows (28–30 kg) were canulated and assigned to crates using a double, 4 × 4 Latin Square design. Pigs were fed each of the 4 diets at 3 times metabolic BW (0.09  BW kg 0.75) for 7 d. Ileal digesta was collected for 12 h on d 6 and d 7 by attaching plastic bags to the cannula. Feed and ileal digesta were analyzed for N, energy and P. Phytase had no effect on apparent ileal digestibility (AID) of N or AAs. The AID of some AAs was higher in the high-phytin diet, which contradicts the hypothesis that higher phytin content would have a negative impact. In contrast, the AID of P was depressed by high dietary phytin (P < 0.01) and increased by phytase (P < 0.01) more so at the higher dietary phytin resulting in a phytin × phytase interaction (P < 0.01).  相似文献   

18.
M. Terr  M. Devant  A. Bach 《Livestock Science》2006,105(1-3):109-119
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.  相似文献   

19.
Six ileal-cannulated pigs that averaged 100 kg BW and 16 adult cecectomized cockerels that averaged 2.35 kg BW were used to determine apparent and true digestibilities of amino acids (AA) in a complete crystalline AA mixture and in casein. A protein-free (PF) diet was included as a treatment to estimate endogenous AA losses. Fasted cockerels were compared to cockerels fed PF diets for calculation of true digestibility of AA in cockerels. For the AA diet, true digestibility of indispensable AA in the pig ranged from a low of 97.2% for leucine to a high of 100.5% for arginine (Arg). True digestibility of indispensable AA in casein ranged from a low of 93.5% for isoleucine (Ile) to a high of 99.9% for Arg. Correcting for endogenous losses increased digestibilities of lysine (Lys) and threonine (Thr) in pigs fed the AA diet by 2.4 and 7.1%, respectively, and increased Lys and Thr digestibility in pigs fed the casein diet by 1.8 and 6.1%, respectively. Feeding a PF diet to chickens to correct for endogenous losses resulted in higher true digestibility values for all AA with the exception of tryptophan, methionine, and Arg than those obtained using fasted animals. True digestibilities of Thr were 88.3 and 86.6% for AA and casein diets, respectively, using fasted controls but were 97.5 and 94.5% when the PF control was used. Proline digestibility was increased (P < .05) substantially in both pigs and cockerels when the PF control was used to correct for endogenous AA losses. Regardless of species, Ile in casein had a lower true digestibility value than any other indispensable AA. The results of this study indicated that true digestibilities of AA in a mixture of crystalline AA and in casein are essentially 100% in both pigs and cockerels.  相似文献   

20.
Four mature Icelandic geldings were used in a balance trial to investigate the effect of stage of maturity of timothy (Pleum pratence L.) haylage fed at maintenance level on coefficients of total tract apparent digestibility (CTTAD), and nitrogen and energy metabolism in a 4 × 4 change-over arrangement of treatments. The content of fibre increased and crude protein content decreased with advancing stage of maturity. Very high CTTAD values were found for DM, OM, CP, CF, NDF and ADF in the first two cuts. Overall, there was a negative relationship between stage of maturity (p < 0.05) and the CTTAD of all measured dietary components. Nitrogen (N) intake, N losses in urine and N balance were affected (p < 0.05) by stage of maturity, while the N losses in the faeces were unaffected. There was a strong correlation (r2 = 0.95) between N balance and water intake. Gross energy intake and losses in urine (as % of digestible energy intake) were unaffected by stage of maturity, while the energy balance was affected (p < 0.05). The digestible energy content of the timothy haylage studied ranged from 14.1 to 9.0 MJ/kg DM.

In conclusion, early-cut timothy haylage (stem elongation to flowering) has the energy content required to form the basis of diets for high-performing horses. Late-cut timothy haylage (seeding to late seeding), on the other hand, can be used to fulfil the energy and protein needs of maintenance-fed Icelandic horses.  相似文献   


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