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1.
1. Two experiments were performed to study the relationship between apparent metabolisable energy (AME) and true metabolisable energy (TME) values at different feed intakes. Rhode Island Red (RIR) adult cockerels were used in two bioassays, under standard conditions. 2. In the first experiment (precision feeding) the birds were not fed for 24 h and then various quantities of maize were fed. There were 6 replicates per treatment. Droppings voided during the 48 h of the experimental period were collected and assayed for gross energy and nitrogen. 3. In the second experiment, each bird was given a 3-d adaptation period, fasted for 24 h and then given maize as an admixture (conventional addition method: CAM) to the same rations as those used in the first experiment. During the 3 d of the experimental period, droppings were collected and frozen for chemical analysis. 4. The results showed that mean metabolisable energy (ME) values obtained by the precisionfeeding procedure were higher than those obtained by CAM. The endogenous energy loss (EEL) (FE m + UE e ) determined by precision feeding was lower than that given by CAM. 5. It was concluded that the method of feeding does not influence ME of maize at different feed inputs. However, differences among intercepts of the regression between ME and feed input suggest that EEL varies at different maize inputs. 6. The optimum maize quantity was approximately 35 to 40 g for adult RIR cockerels by both procedures.  相似文献   

2.
1. Endogenous losses of amino acids (EAAL) and energy (EEL) were determined in unfed adult cockerels. The intercepts of linear regression analysis were determined using 44 birds precision-fed on maize. During the experimental period (48 h), excreta of birds were collected, and the samples of maize and the excreta were dried, ground and assayed for gross energy and amino acids. 2. The EAAL and EEL in unfed cockerels influenced true available amino acid (TAAA) values. Therefore, the intercept of regressions showed an increase in TAAA values of maize. 3. The results indicated that there was no significant difference between the data obtained for EEL from the unfed birds and from regression analysis so, the figure from regression analysis could be used for calculating the true metabolisable energy (TME) value of maize. 4. The calculated EAAL from regression analysis caused an increase in the TAAA value in maize. The amounts of metabolic and endogenous amino acid excretions varied in voided excreta from unfed birds. These differences would be related to genetics, age, sex and environmental temperatures.  相似文献   

3.
1. A common reference procedure adopted by several European laboratories to determine apparent metabolisable energy corrected to zero-nitrogen balance (AMEn) is described. 2. Reproducibility has been estimated by comparing results from 4 diets measured in 7 laboratories. The standard deviations between laboratories of dry matter, gross energy, Kjeldahl nitrogen and AMEn were respectively, on average, 11.29 g/kg, 0.242 MJ/kg, 1.56 g/kg and 0.380 MJ/kg dry matter; the corresponding coefficients of variation between laboratories were 1.27, 1.29, 4.39 and 2.92%. 3. Effect of food intake was tested by comparing AMEn from birds fed either 0.90 or 0.45 of ad libitum: the amount of food intake had a negligible effect on AMEn values. Endogenous energy losses corrected (EELn) or not (EEL) to zero nitrogen balance were estimated either by regression between excreted energy and ingested energy or in fasted and glucose-fed cockerels. EELn estimated by regression was, on average, 8.7 kJ/bird/d.; it was independent of diet composition. EEL and EELn determined in fasted or glucose-fed birds were higher than those determined by regression. 4. AMEn values measured by individual laboratory procedures were very close to those obtained by the reference method, except from laboratories using a tube feeding procedure, where deviations were probably a consequence of overestimated EEL.  相似文献   

4.
1. The endogenous energy (EEL) and nitrogen losses of adult cockerels were studied during both when the animals were starved and when they were fed on a highly digestible nitrogen-free diet. The birds were fed three intakes by intubation and the effects of these intakes were compared. 2. During the 48-h study, the excretion of energy (EEL) was found to be 49.4 kJ, when the birds were given food. When starved this estimate was considerably higher, 70.3 kJ. 3. When endogenous energy per 48 h was corrected to zero nitrogen balance (EEL0), the value of starved animals of 30.1 kJ was still considerably higher than the 13.4 kJ for fed birds. 4. It was concluded that feeding a nitrogen free, highly digestible diet reduces the excretion of endogenous energy. Thus determinations from starved birds appear to give biased estimates of EEL and EEL0. Hence, true metabolisable energy values would also be overestimated where endogenous energy values from starved birds were used.  相似文献   

5.
1. Several different methods of assaying the metabolisable energy (ME) of ground maize and a maize and glucose mixture were studied. Over a 24‐h period fasted cockerels lost more energy and nitrogen in their excreta than those fed 15 g maize and 15 g glucose monohydrate.

2. Discrepancies in ME values of maize were found between 1) Hill's method (substitution for glucose) and 2) Sibbald's method (the difference between energy ingested and excreted, corrected for endogenous losses by a comparison with fasted controls). These discrepancies were attributed to differences in endogenous energy losses between fed and fasted birds and interactions between the test substance and reference diet.

3. No significant differences could be detected when substitution for glucose was compared to substitution for the entire diet in three experiments.

4. Significant differences in the ME of maize because of the composition of the basal diet were found (semi‐purified: practical; 17·20:14·56 kJ/g; and 50 g/kg added fat: 100 g/kg added fat; 15·94:16·69 kJ/g).

5. Food intakes equal to 70, 60 or 30% of ad libitum did not affect the ME of maize when the substitution for glucose method was used.

6. It is concluded that basal diets for ME determinations should be carefully selected because of possible interactions between dietary components. When ME is determined by feeding small amounts of the test material, endogenous losses may be over‐estimated because the control birds are in a different physiological state (fasted).

  相似文献   

6.
1. A precision feeding experiment was conducted with turkeys, which had previously been fed diets with or without phytase, to study the effects on the excretions of endogenous energy (EEL), nitrogen (ENL), amino acids (EAAL) and minerals. 2. Female turkeys (BUT 6) which had been fed one of 4 experimental diets (low P maize-soya diets (control, C), C + 250 international units of phytase/kg diet (FTU), C + 500 FTU and C + 2500 FTU) were used in this study. All birds were fasted and then given 50 mL of glucose solution at 46 d of age. Birds were allocated to individual metabolism cages in a randomised block design with 8 replicates for each of the 4 previously-fed diets. 3. The response of EEL and ENL to phytase pre-exposure was linear. An increase of 100 FTU reduced the EEL and ENL by approximately 1·6 kJ and 20 mg respectively. The results suggest that a minimum activity of phytase of 500 FTU is needed to initiate the reduction of these losses. 4. Pre-exposure to phytase reduced the EAAL, which was best described as a linear response with increasing phytase dose in the pre-study period. An increase of 100 FTU reduced the losses of total endogenous amino acids by approximately 225 mg. 5. In contrast to the results for endogenous energy losses, turkeys pre-exposed to phytase linearly increased their excretions of Ca and Mg with increasing phytase activity in the pre-study period. 6. The effects of feeding turkeys with supplementary phytase continued for at least 4 d after the diets were withdrawn. This suggests that exposure to phytase alters the functionality and secretions of the gastrointestinal tract, which may influence the nutritive value of diets fed immediately after.  相似文献   

7.
1. Energy balance of adult hens divergently selected for high (R + ) or low (R- ) residual food consumption was investigated using indirect calorimetry. Three experiments were conducted: feeding behaviour of individual hens, hens having free access to food or fasting and hens tube-fed at 70, 100 or 130% of the control intake of both lines. 2. R + hens ate significantly more than R- (+ 48%). This difference was maximum at the onset of the light (+ 120%) and not significant during the rest of the light period. Although both lines spent the same total time eating, R + hens exhibited more frequent but shorter meals than R- ones, suggesting a higher feeding activity in R + hens. 3. True metabolisable energy (TME) intake was 28% greater in R+ than in R- birds. Basal heat production did not differ significantly between genotypes. Heat increment of feeding (HI) or diet-induced thermogenesis was significantly enhanced in R + birds: + 23.9 vs 13.7 kJ/100 kJ TME intake in R- . 4. When tube-fed and placed in darkness, restricted-fed R + hens had the same HI as R- birds. When fed at 100% and 130% of control intake, R + hens demonstrated a regulatory thermogenesis, which allowed them to dissipate the excess of energy ingested compared to R- hens. 5. No significant modification was observed in plasma triglyceride, phospholipid, uric acid, glucose or insulin concentrations between lines, suggestive of the use of similar thermogenic pathways. While plasma triiodothyronine (T3) concentrations did not differ between genotypes, plasma thyroxine (T4) appeared higher in unfed R + birds and equal in fed conditions in both lines. 6. A regulatory part of HI allowed R + hens to get rid of their excessive energy intake. An increased turnover of lipids could be involved.  相似文献   

8.
Long-term feed withdrawal has been shown to increase ileocecal intestinal colonization and fecal shedding of Salmonella enterica serovar Enteritidis in challenged hens. Less information is available regarding effects of fasting on crop colonization. Two trials were conducted to compare effects of 14-day feed withdrawal vs. full feed on crop colonization in hens challenged with Salmonella Enteritidis. The levels of Salmonella Enteritidis in the crops of fasted hens were significantly higher than in nonfasted hens on days 3 and 10 and days 3, 9, and 16 postinfection (PI) in trials 1 and 2, respectively. Fecal shedding of Salmonella Enteritidis was significantly increased in the fasted hens on day 10 PI in trial 1. Analysis of crop IgA anti-Salmonella Enteritidis lipopolysaccharide levels in crop lavage samples of hens in trial 1 revealed a humoral response PI in both treatment groups with no significant differences, although peak response for fasted hens occurred 1 wk later. Histologic evaluation of hematoxylin and eosin-stained crop sections from trial 1 birds revealed mild to moderate heterophilic infiltration within the crop lamina propria (LP) or LP and epithelium of nonfasted infected hens at 24 and 96 hr PI. In comparison, heterophils in crops of fasted hens infected at this time point were sparse, indicating a possible diminished heterophil response in the fasted birds. Multifocal areas of tissue inflammation, as indicated by marked heterophil infiltration, with necrosis and sloughing of epithelium, were observed in crops from fasted hens at day 11 PI (14th day of feed withdrawal) but not in the fed groups. This severe heterophilic inflammation was observed in both challenged and nonchallenged fasted hens, suggesting that some factor other than Salmonella Enteritidis was responsible. These results indicate that feed withdrawal can have a dramatic effect on the integrity of the crop and its ultimate response to infection.  相似文献   

9.
1. The efficiency of utilisation of metabolisable energy (ME) for maintenance (k(m)) from diets containing maize and broken rice (BR) at 500 g/kg was studied in old White Leghorn (WL) and Rhode Island Red (RIR) laying hens using the respiration calorimetry technique. The maize-based diet contained 180.8 g crude protein (CP)/kg and 16.4 MJ gross energy (GE)/kg while the BR-based diet contained 173.2 g CP/kg and 16.3 MJ GE/kg. Diets were fed for 10 d, while an energy and nitrogen metabolism study was conducted during 3 d on an ad libitum-fed diet followed by another 3 d on two-thirds of the ad libitum-fed quantity. 2. ME values for the maize- and BR-based diets for WL hens were 73.3% and 77.6% of the GE, whereas for the RIR hens these were 77.7% and 80.0%, respectively. 3. Fasting heat productions, determined at the end of 24 h fast for WL and RIR hens were 473.2 and 366.1 kJ/kg W0.75/d, respectively. During fasting WL and RIR hens utilised body energy reserves with efficiencies of 84.9% and 73.7%, respectively. 4. The k(m) of maize- and BR-based diets for the WL hens were 81.6% and 79.6%, whereas for the RIR hens these were 74.2% and 76.0%, respectively. 5. ME for maintenance of WL and RIR hens were 589 and 499.6 kJ/kg W0.75/d, respectively. 6. It is concluded that although WL and RIR hens differ significantly in energy metabolism, their efficiency of utilisation of energy from maize- and BR-based diets are similar.  相似文献   

10.
The objective of this study was to investigate the effect of dietary protein level on nitrogen retention and compare nitrogen metabolism in Lohmann Brown adult roosters and layers. The nitrogen maintenance requirement ( Nm ) was determined based on the nitrogen balance. Thirty Lohmann Brown adult roosters and 30 laying hens at 27 weeks of age were randomly divided into five groups of six birds per group. The birds were fed with one of five diets containing 10.46%, 11.77%, 13.79%, 16.77% or 18.29%of crude protein. Nitrogen intake, nitrogen retention and nitrogen retention efficiency were higher in roosters than in laying hens, and the average nitrogen retention rate for groups fed with CP level of 11.77%,13.79%, 16.77% and 18. 29% was improved by 9.14%. The nitrogen maintenance requirement for Lohmann Brown roosters and laying hens at 27 weeks of age were 0.4245 g/d and 0.5059 g/d, respectively,and Nm based on average body weight (BW) and metabolic body weight ( BW0.75 ) was 0.2364 g/kg BW and 0.2739 g/kg BW0.75 for laying hens and 0.2754 g/kg BW and 0.3208 g/kg BW0.75 for roosters, respectively. The regression equations for daily N gain ( NB, protein accretion) vs. daily N intake ( NI )for Lohmann Brown layers and roosters were NB =0.3743NI -0. 1589(R2 =0.79) and NB =0.6228NI -0.3151 (R2 =0.85),respectively. The results of this study indicate that nitrogen intake and nitrogen retention at the same dietary CP level were higher in roosters than in laying hens.  相似文献   

11.
鹅和鸡4种常用饲料原料的代谢能比较   总被引：1，自引：0，他引：1  
本试验旨在比较鹅和鸡常用饲料原料的代谢能差异.选用体重为(3.76±0.23)kg的成年扬州鹅(公)和体重为(2.57±0.17)kg的成年新扬州鸡(公)各10只,采用Sibbald真代谢能法测定玉米、豆粕、稻谷、麦麸4种常用饲料原料的代谢能值,内源能测定采用饥饿法.结果表明:玉米、豆粕的表观代谢能(AME)鹅与鸡差异不显著(P＞0.05),真代谢能(TME)鹅显著低于鸡(P＜0.05);而稻谷、麦麸的AME鹅显著高于鸡(P＜0.05),TME鹅与鸡差异不显著(P＞0.05).每小时内源能排出量,除强饲豆粕条件下鹅略高于鸡但差异不显著外(P＞0.05),强饲其他3种饲料条件下,鹅均显著高于鸡(P＜0.05).由此表明,鹅的饲料代谢能与鸡的并不完全相同,部分饲料的代谢能鹅和鸡之间存在显著差异,并且鹅的内源能排出量高于鸡.  相似文献   

12.
As part of a series of studies to characterize innate and specific immune responses of indigenous chicken lines, birds from Bolivia and India were screened serologically for MHC class IV (BG) polymorphism by direct haemagglutination using haplotype-specific antisera (B2, B4, B12, B13, B14, B15, B19, B21). The sample consisted of 95 Bolivian indigenous chickens and 119 hens from the four most common North Indian 'back-yard' chicken lines: Yellow Aseel (AP), Kadaknath (KN), frizzled typed (Ff-) and naked neck (NN). Of all chickens tested, the majority were haplotyped as B2, B15, B19 and B21. Of the Bolivian chickens, 89.5% could be haplotyped: 54.9% were homozygous (including 43.3% B15), and 34.6% were heterozygous (including 15.7% B15). B2-like haplotypes were not found among the Bolivian hens, and only 3.2% of these birds showed homozygous B21-like proteins. Of the Indian hens, MHC (BG)-like proteins could be detected in 60.0% of the AP birds, 6.7% of the KN birds; 40.0% of the Ff- birds; and 10.3% of the NN birds. In these lines, a total of 40.1% (AP), 6.7% (KN), 30.1% (Ff-) and 10.3% (NN) were homozygous for the B-haplotype. Only in the AP line (19.9%), and the Ff- line (9.9%) were heterozygous B-haplotypes types found. The B2 haplotype was found in all Indian chicken lines. Most Indian birds have completely unknown haplotypes, indicating a potentially interesting genetic pool. Subgrouping the Bolivian and Indian indigenous hens into monomorphic BG populations revealed individual differences based on the B-types.  相似文献   

13.
The objective of this study was to investigate the effect of dietary protein level on nitrogen retention and compare nitrogen metabolism in Lohmann Brown adult roosters and layers. The nitrogen maintenance requirement (Nm) was determined based on the nitrogen balance. Thirty Lohmann Brown adult roosters and 30 laying hens at 27 weeks of age were randomly divided into five groups of six birds per group. The birds were fed with one of five diets containing 10.46%, 11.77%, 13.79%, 16.77% or 18.29% of crude protein. Nitrogen intake, nitrogen retention and nitrogen retention efficiency were higher in roosters than in laying hens, and the average nitrogen retention rate for groups fed with CP level of 11.77%, 13.79%, 16.77% and 18.29% was improved by 9.14%. The nitrogen maintenance requirement for Lohmann Brown roosters and laying hens at 27 weeks of age were 0.4245 g/d and 0.5059 g/d, respectively, and Nm based on average body weight (BW) and metabolic body weight (BW0.75) was 0.2364 g/kg BW and 0.2739 g/kg BW0.75 for laying hens and 0.2754 g/kg BW and 0.3208 g/kg BW0.75 for roosters, respectively. The regression equations for daily N gain (NB, protein accretion) vs. daily N intake (NI) for Lohmann Brown layers and roosters were NB = 0.3743NI–0.1589 (R2 = 0.79) and NB = 0.6228NI–0.3151 (R2 = 0.85), respectively. The results of this study indicate that nitrogen intake and nitrogen retention at the same dietary CP level were higher in roosters than in laying hens.  相似文献   

14.
1. Metabolisable energy values (AME, AMEn, TME and TMEn) of three raw materials (maize, sunflower meal and soyabean meal) were determined in adult cockerels using two classical feeding e techniques (ad libitum and force-feeding of dry food) and a new one in which birds were force-fed wet diets. 2. In the wet force-feeding assay nitrogen balances and food intakes were similar to those achieved with ad libitum feeding. The duration of the assay using wet force-feeding was only 2 d as compared to the 3 or 7 d experimental periods for the dry or the ad libitum assays respectively. 3. TMEn values were not dependent on the feeding technique used; AME and AMEn data obtained in the ad libitum and wet force-feeding assays were close to TMEn values. As expected, these values were underestimated in the dry force-feeding assay.  相似文献   

15.
1. This trial studied the effects of strain and age on tonic immobility (TI) duration, emergence time (ET) and social reinstatement time (SRT) in laying hens and investigated the consistency of individual behavioural characteristics over rearing and laying periods and the correlations between these behavioural traits. 2. One hundred chicks from each of ISA Brown (ISA) and Lohmann Tradition (LT) laying hens were reared from one day old in pens. At 3 weeks, birds of each line were divided into 4 groups. Twenty birds in one group of each line were marked individually for repeated testing and the other groups were assigned for single testing to test the habituation effect and possible age effects at a group level. 3. ISA birds had higher overall means for TI duration and latency to leave the start box. ISA also showed longer latency in SRT at week 28 than Lohmanns. TI duration increased from weeks 3 to 10 and then decreased to week 35 in both lines. The latency to explore the test area and to reinstate decreased from weeks 10 to 35. 4. Tonic immobility, exploratory and social reinstatement behaviours were consistent over time in both lines, as revealed by Kendall's W coefficient of concordance. 5. In social test situations, an inter-situational consistency was found, that is, birds emerged quickly from the start box and reinstated quickly with their companion. TI (non-social test) was negatively correlated with ET and SRT. Thus the two lines of laying hens respond differently in social and non-social tests.  相似文献   

16.
1. The effect of long-term, moderate heat stress (30 to 32 degrees C) on heat shock protein 70 (Hsp70) concentration in mononuclear blood cells and plasma concentrations of 3,5,3'-triiodothyronine (T3) and corticosterone in laying hens was investigated. 2. Three groups of 48 hens each (Ethopian line [Angete Melata, Na], New Hampshire [NH], F1 cross [Na x NH]) were divided into an experimental group (24 each) and a control group (24 each, ambient temperature 18 to 20 degrees C), respectively. All hens were kept in individual cages up to an age of 68 weeks and performance data were recorded. 3. Blood samples were taken from the wing vein of 12 hens from each group at weeks 22, 38, 51 and 65 (12 hens x 3 lines x 2 treatments). Mononuclear blood cells were isolated and Hsp70 concentrations were determined by Western Blot analysis with a monoclonal anti-Hsp70 antibody. T3 and corticosterone were measured with commercially available ELISA and RIA kits, respectively. 4. The moderate heat stress caused significantly increased Hsp70 levels compared with the control groups in weeks 51 and 65. However, the responses of the lines were not uniform at different ages. 5. In contrast, T3 levels were significantly decreased in stressed birds regardless of line and age. There was no effect of treatment and line on corticosterone levels during the experimental period. 6. Our results indicate that Hsp70 and T3 levels are affected by mild heat stress applied over a long period but are both involved in independent mechanisms of acquisition of thermotolerance. Further investigations are necessary to clarify whether the observed differences in Hsp70 response between the genotypes are indicators for differences in thermotolerance.  相似文献   

17.
1. An experiment was carried out to examine the suitability of using maize silage, barley-pea silage and carrots as foraging materials for egg-laying hens. Production performance, nutrient digestibility, gastrointestinal characteristics, including the composition of the intestinal microflora as well as feather pecking behaviour were the outcome variables. 2. The protein content of the foraging material (g/kg DM) was on average 69 g in carrots, 94 g in maize silage and 125 g in barley-pea silage. The starch content was highest in the maize silage (312 g/kg DM), and the content of non-starch polysaccharides (NSP) varied from 196 to 390 g/kg, being lowest in carrots. Sugars were just traceable in the silages, whereas carrots contained on average 496 g/kg DM. 3. Egg production was highest in hens fed either carrots or maize silage, whereas hens fed barley-pea silage produced less (219 vs. 208). Although the consumption of foraging material was high (33, 35 and 48% of the total feed intake on 'as fed' basis for maize silage, barley-pea silage and carrots, respectively) only a minor effect on nitrogen corrected apparent metabolisable energy (AME(n)) and apparent digestibility was seen. At 53 weeks of age, hens fed maize silage had AME(n) and apparent digestibility values close to the control group (12.61 and 12.82, respectively), whereas access to barley-pea silage and carrots resulted in slightly lower values (12.36 and 12.42, respectively). Mortality was reduced dramatically in the three groups given supplements (0.5 to 2.5%) compared to the control group (15.2%). 4. Hens receiving silage had greater relative gizzard weights than the control or carrot-fed groups. At 53 weeks of age, the gizzard-content pH of hens receiving silage was about 0.7 to 0.9 units lower than that of the control or carrot-fed hens. Hens fed both types of silage had higher concentrations of lactic acid (15.6 vs. 3.2 micromoles/g) and acetic acid (3.6 vs. 6.1 micromoles/g) in the gizzard contents than the other two groups. The dietary supplements had a minor effect on the composition of the intestinal microflora of the hens. 5. Access to all three types of supplements decreased damaging pecking in general (to feathers as well as skin/cloaca), reduced severe feather pecking behaviour and improved the quality of the plumage at 54 weeks of age. 6. In conclusion, access to different types of foraging material such as silages and carrots improved animal welfare.  相似文献   

18.
An experiment was conducted to evaluate the effect of scavenging on diet selection and the comparative performance of Rhode Island Red and Fayoumi breeds of chicken. The breeds were compared under three feeding/management regimes: (1) a choice of ground noug cake and cracked maize, with confinement; (2) a choice of ground noug cake and cracked maize, but being allowed to scavenge for about 6 h; and (3) a commercial layer mash, with confinement. Scavenging did not change the pattern of diet selection. About 90% of the daily intake of both the confined and scavenging birds under choice feeding comprised maize. The efficiency of feed utilization and nutrient intake were also similar in these groups. The Fayoumi were more efficient in terms of feed conversion, although the egg production performance of the two breeds did not vary significantly. Scavenging hens had a significantly lower egg production than the birds under confinement offered a choice of feeds. Scavenging significantly increased the mortality in both breeds. In conclusion, scavenging affected the performance adversely and, despite the provision of a choice of feed providing a source of energy and protein, both the scavenging and confined birds on choice feeding failed to eat sufficient to meet their protein requirements.  相似文献   

19.
A 24-week performance trial was conducted to evaluate the efficacy of an experimental phytase on performance, egg quality, tibia ash content and phosphorus excretion in laying hens fed on either a maize- or a barley-based diet. At the end of the trial, an ileal absorption assay was conducted in order to determine the influence of phytase supplementation on the apparent absorption of calcium and total phosphorus (P). Each experimental diet was formulated either as a positive control containing 3.2 g/kg non-phytate phosphorus (NPP), with the addition of dicalcium phosphate (DCP), or as a low P one, without DCP addition. Both low P diets (containing 1.3 or 1.1 g/kg NPP) were supplemented with microbial phytase at 0, 150, 300 and 450 U/kg. The birds were housed in cages, allocating two hens per cage as the experimental unit. Each of 10 dietary treatments was assigned to 16 replicates. Low dietary NPP (below 1.3 g/kg) was not able to support optimum performance of hens during the laying cycle (from 22 to 46 weeks of age), either in maize or barley diets. Rate of lay, daily egg mass output, feed consumption, tibia ash percentage and weight gain were reduced in hens fed low NPP diets. The adverse effects of a low P diet were more severe in hens on a maize diet than in those on a barley diet. Low dietary NPP reduced egg production, weight gain, feed consumption and tibia ash content and microbial phytase supplementation improved these parameters. Hens given low NPP diets supplemented with phytase performed as well as the hens on positive control diets containing 3.2 g/kg of NPP. A 49% reduction of excreta P content was achieved by feeding hens on low NPP diets supplemented with phytase, without compromising performance. Phytase addition to low NPP diets increased total phosphorus absorption at the ileal level, from 0.25 to 0.51 in the maize diet and from 0.34 to 0.58 in the barley diet. Phosphorus absorption increased linearly with increasing levels of dietary phytase. Mean phosphorus absorption was higher in barley diets than in maize diets (0.49 vs 0.39).  相似文献   

20.
1. During a cycle of 14 h artificial light and 10 h darkness, dry matter and enzyme concentrations were measured in the pancreas and gut of egg-forming hens. 2. Dry or fresh pancreas weight did not show significant variation but pancreatic enzyme activities increased gradually from 2 to 22 h after oviposition. 3. Total wet and dry matter contents of the small intestine gradually increased from 2 to 18 h after oviposition and then decreased significantly. Intestinal tryptic activity followed the same pattern whereas intestinal amylase gradually decreased from 2 h after oviposition; intestinal lipase activity tended to decrease during the light period (2 to 10 h after oviposition) and to increase during the dark period (14 to 22 h after oviposition). 4. By contrast, patterns of enzyme activity in the pancreas were similar. It is proposed that modification of the chyme and transit rates during the day may affect pancreatic enzyme fate and distribution in the small intestine. 5. In non-egg-forming birds intestinal contents and enzyme activities were less than in egg-forming birds. The reverse was observed in the case of the pancreas where contents and enzyme activities were increased. A relationship with food intake pattern is discussed.  相似文献   

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