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1.
1. Two experiments are described in which laying pullets maintained at constant temperatures were fed a range of diets with a view to defining optimum combinations of temperature and nutrient intake. 2. In the first experiment, all combinations of 6 temperatures (15 degrees, 18 degrees, 21 degrees, 24 degrees, 27 degrees and 30 degrees C) 9 diets (three protein concentrations and three energy contents) and two stocks were tested for 34 weeks using 4320 pullets. In experiment 2, all combinations of three rearing temperatures, three laying temperatures (18 degrees, 22.5 degrees and 27 degrees C) three diets (protein concentration) and two stocks were tested for 61 weeks using 2160 pullets. 3. As anticipated, higher dietary protein concentrations were needed to maintain egg output at higher temperatures. If diets suplying adequate amino acid intakes were provided, egg output was unaffected by temperatures in the range 15 degrees to 27 degrees C although, at the highest temperature, egg weight was slightly reduced and rate of lay (particularly in the later part of the laying year) was increased. At 30 degrees C, egg output was depressed whichever diet was fed. 4. Dietary energy content had small but significant effects on egg weight and egg output but did not interact with temperature. It was not possible to maintain egg weight or egg output at 30 degrees C by feeding a high energy, high protein diet. 5. Estimated heat output of the birds increased during the course of the experiment at the lower temperatures but decreased with time at 30 degrees C. Feather loss occurred earlier at the lower temperatures and this is interpreted as an effect of temperature on the timing of the annual moult, which also accounts for the better persistency of lay observed at 27 degrees C. 相似文献
2.
1. Pullets allowed to self-select nutrients from a protein concentrate and either a separate complete diet or cereal-based, energy-rich mixture showed preferences for protein and energy which varied in relation to the time of their onset of lay. 2. The selected protein:metabolisable energy (ME) intake ratio increased from 14 g protein per MJ of ME 2 to 3 weeks before sexual maturity to approximately 19 g protein per MJ of ME at and after sexual maturity. 3. This response to self-selection feeding was consistent with different temperatures, lighting patterns and dietary manipulations. 4. Egg mass output was improved by self-selection feeding at hot (25 degrees to 35 degrees C) temperatures in experiments 1 and 2 and at ambient temperatures in experiment 3. No beneficial response in egg mass from self-selection feeding was observed at cold (6 degrees to 16 degrees C) temperatures in experiment 1. 5. Providing 2 h of additional light during the dark (cool) part of the day, with or without 2 h of darkness in the middle of the extended light (hot) period, had no effect on the egg mass output of pullets at hot (25 degrees to 35 degrees C) temperatures. 相似文献
3.
1. The data compiled by Marsden and Morris (1987) to examine the relationships between environmental temperature and the long-term, adapted responses of laying pullets were divided at random into two subsets of 99 and 113 observations. The first subset was used to estimate regression coefficients for an econometric model, and the second subset to validate the model. 2. Equations to predict inputs (costs) and outputs (returns) were estimated with a three-stage least-squares regression model. Three stage least-squares estimation is a technique which corrects for the simultaneity of variables within the model and correlation across equations of the model. This results in more efficient estimates of the regression coefficients. 3. The final output and output equations were: MEI = 253.86-190.31EM+5.766EM2-0.546EM3 + 0.7034T-0.004388T3 + 695.08BW-120.23BW2 + 397.37ME-13.132ME2-1.06MEXT; R2 = 0.86; EO = 119 + 0.025MEI -0.0000045MEI2-1.462T-0.0791T2-135.3BW + 38.31BW2-1.483T X BW + 0.0288T2 X BW + 0.673 delta BW; R2 = 0.59 where MEI = daily metabolisable energy intake (kJ/bird d), T = environmental temperature (degree C), EO = egg output (g/bird d), BW = body weight, and ME = metabolisable energy concentration (kJ/g). The values for R2 indicate very good fits considering that the data were recorded over a 26-year period in 14 different laboratories. 4. This statistical model can serve as the basis for an econometric model of egg production to determine the environmental temperature that maximises profits from laying pullets of different body weights. 相似文献
4.
1. Lohmann White and Lohmann Brown egg-type hybrids were reared on 6-, 8-, 10- or 12-h photoperiods, transferred to 12.5 h at 18 weeks and then given weekly increments to reach 14 h at 21 weeks. In a second experiment, Lohmann White pullets from the same rearing facility were transferred abruptly to 14 h at 18 weeks. 2. Body weight gain and feed intake to 6 and 18 weeks were positively correlated with rearing photoperiod in both breeds. Mortality to 18 weeks was unaffected. 3. Whether the photoperiod was increased abruptly or in a series of increments, Lohmann White pullets reared on 6 or 8 h matured 4 to 6 d later than pullets reared on 10 or 12 h. Rearing day-length had little effect on sexual maturity in Lohmann Brown pullets. 4. In both genotypes and each experiment, egg numbers, egg weight and shell strength increased with rearing photoperiod. Feed intake in the laying period was not significantly affected by rearing day-length, but a meta-analysis of all data showed a significant, though small, increase in adult feed intake with rearing photoperiod. Despite Lohmann White birds reared on 6 and 8 h having lower body weights throughout the laying period, they had larger body weight gains between 18 and 70 weeks than those reared on 10 or 12 h. There were no clear effects of rearing photoperiod on albumen height or mortality. 5. The heavier eggs and stronger shells of the birds reared on the longer day-lengths were correlated with heavier body weights at 18 weeks, and the superior egg numbers and higher feed intake were associated with age at sexual maturity. 相似文献
5.
1. Pullets in late growth and early lay were maintained at hot (25° to 35°C) or cold (6° to 16°C) ambient temperatures and either fed complete diets or allowed to self‐select nutrients from separate energy‐ and protein‐rich foods.
2. Manipulating the metabolisable energy (ME) and/or nutrient density (ND) of complete layer diets failed to improve egg output at hot temperatures to that obtained at cold temperatures.
3. At both temperatures self‐selection increased protein, but not ME, intake. This increased egg output and body weight gain at the hot, but not cold, temperatures. At the hot temperatures pullets fed by self‐selection were the only ones to gain weight between sexual maturity and 28 weeks of age.
4. Nutrient intake patterns, related to each pullet's physiological age of sexual maturity, identified distinctive changes in protein intake and the selected protein: ME intake ratio of pullets fed by self‐selection. Pullets attempted to maintain a preferred protein:ME intake ratio, irrespective of the markedly different intakes of ME and protein at the two temperatures.
5. Pullets trained to self‐select nutrients from separate energy‐ and protein‐rich foods are better able to sustain egg output and body weight at sexual maturity when food intake is limited by high ambient temperatures. 相似文献
6.
1. The effect of 100 g rapeseed meal (RSM)/kg diet on the energy metabolism of hybrid laying hens was examined by indirect calorimetry. Thyroid hormone concentrations, thyroid weight, liver weight and body weight, egg production and food intake were also measured. 2. Fasting heat production was significantly lower in hens receiving RSM than in controls, but this difference disappeared when the birds were fed. 3. Thyroid hormone concentrations decreased, while thyroid and liver weights increased slightly; none of these effects was significant. Body weight, egg production and food intake were unaffected and no liver haemorrhages were noted. 4. The maintenance metabolisable energy (ME) requirement of control and treated birds, estimated from short-term energy balance measurements, was 474 kJ/kg0.75 d; net availability of ME in both treatments was 0.85. 相似文献
7.
Increasing dietary metabolisable energy (ME) at particular amino acid: ME ratios significantly improved growth and food utilisation of broilers kept at moderate (18 to 26 degrees C) and high (25 to 35 degrees C) ambient temperatures during the finishing period from 22 d of age. The optimum amino acid: ME ratio varied with dietary ME concentration in the hot, but not in the moderate environment. Relatively greater increases in food intake and growth rate occurred in the hot environment when dietary ME was increased and the amino acid: ME ratio was reduced. The minimum rate of food intake did not coincide with the period of maximum temperature. Increasing the dietary protein at particular ME concentrations had little or no effect on the food intake and growth rate of birds kept at high temperatures. Supplementation with dietary fat had no beneficial effect on performance at high temperatures. The rectal temperatures of birds in the hot environment increased with age and, towards the end of the finishing period, when higher energy diets were fed. 相似文献
8.
Heat production, which accounts for 0.6 of gross energy intake, is insufficiently represented in predictions of food intake. Especially when heat production is elevated (for example by lower temperature or poor feathering) the classical predictions based on body weight, body-weight change and egg mass are inadequate. Heat production was reliably estimated as [35.5-environmental temperature (degree C)] x [Defeathering (=%IBPW) + 21]. Including this term (PHP: predicted heat production) in equations predicting food intake significantly increased accuracy of prediction, especially under suboptimal conditions. Within the range of body weights tested (from 1.6 kg in brown layers to 2.8 kg in dwarf broiler breeders), body weight as an independent variable contributed little to the prediction of food intake; especially within strains its effect was better included in the intercept. Significantly reduced absolute values of residual food consumption were obtained over a wide range of conditions by using predictions of food intake based on body-weight change, egg mass, predicted heat production (PHP) and an intercept, instead of body weight, body-weight change, egg mass and an intercept. 相似文献
9.
Influence of dietary energy, nutrient density and environmental temperature on pullet performance in early lay 总被引：1，自引：1，他引：0
1. Alterations in dietary metabolisable energy (ME) concentration had a limited influence on food and nutrient intakes and egg mass output of hens in early lay kept at the prevailing air (10 degrees to 24 degrees C), cold (6 degrees to 16 degrees C) or hot (25 degrees to 35 degrees C) temperatures. 2. Energy intakes were not improved by increasing the dietary concentrations of nutrients other than energy. 3. At prevailing air and cold temperatures all dietary ME-nutrient density combinations allowed hens to meet the recommended daily protein intake but only hens fed the most concentrated diets were able to meet this recommendation at hot temperatures. 4. Even the highest intakes of ME and protein achieved at hot temperatures failed to increase egg mass output to the values attained on any diet at cold temperatures. 相似文献
10.
Rabello CB Sakomura NK Longo FA Couto HP Pacheco CR Fernandes JB 《British poultry science》2006,47(5):622-631
1. The objective of this study was to determine a metabolisable energy (ME) requirement model for broiler breeder hens. The influence of temperature on ME requirements for maintenance was determined in experiments conducted in three environmental rooms with temperatures kept constant at 13, 21 and 30 degrees C using a comparative slaughter technique. The energy requirements for weight gain were determined based upon body energy content and efficiency of energy utilisation for weight gain. The energy requirements for egg production were determined on the basis of egg energy content and efficiency of energy deposition in the eggs. 2. The following model was developed using these results: ME = kgW0.75(806.53-26.45T + 0.50T2) + 31.90G + 10.04EM, where kgW0.75 is body weight (kg) raised to the power 0.75, T is temperature ( degrees C), G is weight gain (g) and EM is egg mass (g). 3. A feeding trial was conducted using 400 Hubbard Hi-Yield broiler breeder hens and 40 Peterson males from 31 to 46 weeks of age in order to compare use of the model with a recommended feeding programme for this strain of bird. The application of the model in breeder hens provided good productive and reproductive performance and better results in feed and energy conversion than in hens fed according to strain recommendation. In conclusion, the model evaluated predicted an ME intake which matched breeder hens' requirements. 相似文献
11.
1. A total of 240 Shaver White and 240 ISA Brown pullets that had been reared in multi-bird cages on a 10-h photoperiod, and maintained at a light intensity of 3 or 25 lux, or changed from 3 to 25 lux or from 25 to 3 lux at 9 or 16 weeks of age, were moved into individual-bird cages at 20 weeks and transferred to 15-h photoperiods at 25 lux. 2. In both breeds, birds transferred from 3 to 25 lux at 16 or 20 weeks laid significantly more eggs than birds maintained on the brighter intensity from one day or increased to it at 9 weeks. 3. Mean egg weight, shell deformation, albumen height, feed intake and body weight gain in lay were not significantly affected by the light intensity treatments during the rearing period. There was, however, a small, but significant, negative correlation of egg numbers with mean egg weight, although this only partially explained the difference in egg numbers. The differences in egg production were unrelated to rate of sexual maturation. 相似文献
12.
Zero-activity heat production (HP), body temperature (Tb) and energy retention were measured in growing broilers maintained at 5 ambient temperatures (Ta) (14 degrees , 17 degrees , 22 degrees , 27 degrees and 32 degrees C) and at 5 feeding rates (ad libitum intake and 75%, 50%, 25% and 0% (fasting) of ad libitum). Zero-activity HP increased with decreasing Ta and increasing food intake. However, at 14 degrees C, zero-activity HP in birds fed ad libitum and 75% did not show further increase, but those in birds fed less than 75% of ad libitum increased rapidly. Results of the regression of zero-activity HP on Ta ranging from 32 degrees to 17 degrees C indicated that the slope was affected little by food intake, but the intercept decreased with decreasing food intake. Tb increased significantly with increasing food intake. There was little variation with Ta but, at and above 27 degrees C, a slightly increased Tb was observed only in birds fed ad libitum. Overall effects of Ta and food intake on HIF (% TME intake) were not found, but HIF tended to increase with decreasing food intake at 14 degrees C. Total energy retention and energy retention as fat decreased with decreasing Ta and food intake, although energy retention as protein decreased only with decreasing food intake. Results obtained here suggest that availability of TME is affected little by Ta ranging from 32 degrees to 17 degrees C and that HIF is utilised, in part, to maintain Tb at any Ta. 相似文献
13.
In an experiment with broilers (origin Tetra B) and with rats (albino, Wistar line) with 2 animals each, heat production was ascertained by measuring CO2 production and O2 consumption over 20 minutes after their feeding 18 h and 1 h before the beginning of measuring at ambient temperatures of 30, 25, 20, 15 and 10 degrees C. Every variant was followed through over 6 h/d in 12 measuring sections. The feed amount/ánimal and day was adapted to energy maintenance requirement. At the beginning of the experiments the broilers and rats were 14 and 21 weeks old resp. and weighed 2.2 kg and 220 g resp. The variation of the ambient temperature did not influence the heat production of the broilers. In contrast to this, the time of feeding in relation to the beginning of measuring had a distinct effect on heat production. Whereas a heat production of 342 +/- 34 kJ/kg LW0.75.d was ascertained in the postabsorptive state 18 h after the last feed intake, it increased by 11% to 393 +/- 32 kJ/kg LW0.75.d when measuring began 1 h after feeding. The very act of feed intake increased heat production by 75%. Rats showed a distinct increase of heat production caused by a decreasing ambient temperature. In the temperature range of 30-25 degrees C the increase was shallower than in the range of 25-10 degrees C. Per 1 degrees C below 25 degrees C heat production increased by 30 kJ/kg LW0.75.d. The increase was independent of the metabolism level, which was influenced by the feeding variants. The results are discussed in connection with Rubner's theory of heat compensation. 相似文献
14.
1. In four trials during consecutive years individually‐caged birds were weighed at first egg, and in the first two trials they were then killed to determine abdominal and skin fat, in order to establish whether there is a minimal body weight and/or body fat pool required for the start of egg production in broiler breeder hens. 2. There were negative correlations ranging from significant to negligible between body weight and age at first egg. For birds of the same strain on a conventional food restriction regimen, the average weight range at first egg in the four trials was 3·3 to 3·7 kg, which may be a strain characteristic. 3. In spite of severe food restriction, all birds were very fat at first egg. The correlations between fat concentration and age at first egg were negative. 4. In mature pullets a minimum concentration of stored, easily mobilised fat may be essential for yolk formation and ovulation. 相似文献
15.
1. Four rearing temperature regimes (15, 20, 25, 30 °C) and three feeding schedules (ad libitum, restricting to the ad libitum intake of the 12th week and feeding 70% of this rate) were carried out with layer replacement pullets to 170 d of age. From this age, during lay, birds were kept at either 21 °C or on a 24‐h cycle of 21 for 18 h and 28 °C for the 6 h before lights out. Both a white and a brown egg‐laying strain were used.
2. Body weight at 169 d of age varied from, on average, 1409 g (15 °C, ad libitum) to 943 g (30 °C, 70% schedule) for the white strain and 1947 to 1250 g for the same treatments respectively for the brown strain. Sexual maturity was considerably delayed by the 70% feeding schedule, only slightly by rearing at 30 °C.
3. Rearing at 30 °C tended to depress subsequent egg output. The 70% feeding schedule at least maintained egg output compared with birds fed ad libitum in rearing.
4. There was a highly significant effect of temperature treatment during lay on food intake. The reduction in food intake due to the 21–28 °C cycle, however, appeared small. 相似文献
16.
The aim of this study was to determine if the negative effects of high ambient temperature (34 degrees C) on egg production, egg quality, digestibility of nutrients, and mineral content of egg yolk could be alleviated by dietary vitamin E (dl-alpha-tocopheryl acetate) supplementation in laying Japanese quails (Coturnix coturnix japanica). Japanese quails (n=240; 7-week-old) were divided into eight groups, 30 birds per group. The quails were fed either a basal diet or the basal diet supplemented with either 125, 250 or 500 mg of dl-alpha-tocopheryl acetate/kg of diet. Birds were kept at 22 degrees C and 55% relative humidity (RH). At 14 weeks of age, the thermo-neutral (TN) group remained in the same temperature as at the beginning of the experiment, whereas the heat stress (HS) group was kept at an environment-controlled room at 34 degrees C and 44% RH for 3 weeks. Heat exposure decreased performance when basal diet was fed (P=0.001). With 250 and 500 mg/kg of diet, an increase in body weight (P=0.01), feed intake (P=0.01), egg production (P=0.001), and improvement in feed efficiency (P=0.01) was found with vitamin E supplementation in quails reared under heat stress conditions (HS). Similarly, egg weight (P=0.01), egg specific gravity (P=0.01), egg shell thickness (P=0.05) and Haugh unit (P=0.01) were positively influenced by vitamin E supplementation. Heat exposure decreased digestibility of dry matter (DM) (P=0.03), organic matter (OM) (P=0.05), crude protein (CP) (P=0.02), ether extract (EE) (P=0.05) and were elevated by supplemental vitamin E (P相似文献
17.
N. Jackson 《British poultry science》1970,11(1):93-102
Two experiments are described in which the daily metabolisable energy intake of laying hens fed a concentrated diet (ME = 3550 kcal/kg) was restricted on an individual hen basis. Performance on this diet was compared with that of hens fed a high‐energy diet (ME = 2690 kcal/kg). In experiment 1 medium‐weight hybrid pullets were used and in experiment 2 two light‐weight hybrid strains were used.
In both experiments maximum egg production was obtained from the birds fed the high‐energy diet ad libitum. Restriction of the concentrated diet caused a significant reduction of body weight gain and a statistically insignificant fall in the total weight of egg product and in percentage production in both experiments.
Restriction of the concentrated diet caused improvements of 22 and 18 per cent in the efficiency of utilisation of metabolisable energy in experiments 1 and 2 respectively.
The data are discussed in relation to the relevant literature and the current cost of concentrated sources of energy. 相似文献
18.
1. The accuracy of equations to predict metabolisable energy intake of laying hens was compared using a random sample of the data set of Marsden and Morris (1987). 2. The equation of Pesti et al. (1992) was found to be significantly better at predicting metabolisable energy intake than the equations of Byerly (1941), Emmans (1974), Byerly et al. (1980), and the National Research Council (1984) when equation residual mean square errors were tested. 3. The equation of Pesti et al. (1992) had the highest coefficient of determination (R2), the smallest average residual, and smallest mean square error. The NRC equation predicted the average metabolisable energy intake best, indicating that over- and under-predictions offset each other. 4. The equations of Emmans (1974) and Pesti et al. (1992) were essentially without bias across temperature zones: less than 20, greater than = 20 less than 25, greater than = 25 less than 30, and greater than = 30 degrees C. The equation of Byerly (1941) over-predicted below 25 and above 30 degrees C, but under-predicted between 25 and 30 degrees C. The equation of Byerly et al. (1980) under-predicted below 30 degrees C while the NRC (1984) equation under-predicted above 20 degrees C. 相似文献
19.
1. The chemical composition of dried papaya (Carica papaya) skin (DPS) was determined and the effect of diets containing different concentrations of this ingredient (0, 30, 60 and 90 g/kg) was studied using growing pullets as experimental animals. 2. Crude protein concentration was determined to be 229 g/kg and metabolisable energy content was estimated to be 6.4 MJ/kg. 3. Use of DPS in the diet up to 90 g/kg did not produce any significant difference in weight gain, food intake, food conversion and protein efficiency when compared with birds that received the control diet. 4. Survivability of growing pullets fed on DPS was 100%, as in the control group. 5. It was concluded that DPS can safely be used up to 90 g/kg in the diet of growing pullets. 相似文献
20.
1. Sex-linked dwarfing genes from 2 broiler stock origins (EU and US) were each introgressed into 2 White Leghorn populations that had been divergently selected for antibody response to sheep erythrocytes. 2. When the resulting backcrossed populations were 87.5% of their respective White Leghorn line, non-dwarf pullets were assessed for body weights, shank lengths, immunoresponsiveness, age and body weight at sexual maturity, egg production, average egg weight, and duration of fertility. For measurements where there were no differences between non-dwarf pullets from the 2 origins of the dwarfing genes, then the dwarf pullets (which were full sisters to the non-dwarfs) were compared. 3. Shank length at 8 weeks of age and mature (24-week) body weights were higher for dwarf pullets from EU than US dwarf origin. Immune response and several egg production traits were higher for dwarf pullets from the high antibody backcross than from those of the low antibody backcross. 4. There were few differences in expression of the dwarfing genes from 2 origins in the unrelated backcross populations used in this study. Also each of the dwarfing genes, when introgressed into different genomic backgrounds, was not discernibly different in its expression in terms of antibody response or egg production characteristics. 相似文献