Investigation on the Possibility of Reducing Protein, Phosphorus, and Calcium Requirements of Laying Hens by Manipulation of Time of Access to These Nutrients 1 K. KESHAVARZ2 Department of Animal Science, Cornell University, Ithaca, New York 14853 ABSTRACT Experiments (Exp.) were conducted to determine whether the daily requirement of laying hens for protein, P, and Ca can be reduced by providing the hens with adequate levels of these nutrients only during those hours of the day that the physiological need for these nutrients for formation of various components of eggs are increasing. In Exp. 1, birds of the positive control were fed a 16% protein diet and birds of the negative control were fed a 13% protein diet continuously during the light period (0500 to 2100 h). The other groups were fed the 16% protein diet during the morning (0500 to 1300 h) and the 13% protein diet during the afternoon (1300 to 2100 h) or vice versa. The design of Exp. 2 was similar to Exp. 1. The birds of the positive control were fed a 0.4% available P (AP) and the birds of the negative control were fed a 0.2% AP diet, with other groups receiving the high-low AP or the lowhigh AP diets during the morning and the afternoon, Received for publication October 6, 1997. Accepted for publication April 14, 1998. 1Supported in part by ISA Babcock, P.O. Box 280, Ithaca, NY 14851-0280. 2To whom correspondence should be addressed: kk33@cornell.edu respectively. The birds of the negative controls in these Exp. had almost comparable performance to those fed the other dietary treatments. As a result, these Exp. did not have negative controls for comparison of different dietary treatments. Additionally, regardless of dietary treatments, birds consumed about 40% of their daily feed intake during the morning and about 60% during the afternoon in these Exp. Due to these two shortcomings, it was not possible to reach to a decisive conclusion pertaining to the objectives of the Exp. The results of Exp. 3 indicated that the above pattern of daily feed intake was not due to an increased appetite for Ca during the afternoon hours for shell formation. Various indices of shell quality were not improved when most parts of the daily Ca need was fed during the afternoon and evening and were not reduced when most parts of the daily Ca need was fed during the morning. (Key words: protein level, phosphorus level, calcium level, pattern of feed intake) INTRODUCTION Considerable quantities of N and P are excreted annually by commercial laying hens to the environment. Furthermore, protein and P are the two most expensive components in poultry rations. Consequently, any approach that could potentially reduce the intake and, as a result, the excretion of these nutrients without affecting the hen s productivity would have a significant impact in reducing the environmental pollution attributed to these nutrients and the cost of egg production. One approach for reducing N excretion is the use of low-protein amino acid-supplemented diets. It has been shown that satisfactory performance can be obtained by moderately reducing the dietary level of protein with proper amino acid supplementation. 1998 Poultry Science 77:1320 1332 However, when the protein level in the diet is reduced more drastically, production performance cannot be satisfactorily maintained with low-protein, amino-acid supplemented diets as with crude protein (Keshavarz et al., 1980; Keshavarz, 1984, 1986; Calderon and Jensen, 1990; Jensen et al., 1990; Penz and Jensen, 1991; Summers et al., 1991; Keshavarz and Jackson, 1992; Summers, 1993; Leeson and Caston, 1996). The possible reasons for the failure of the low-protein, amino acid-supplemented diet in maintaining optimum performance and the information that is required to overcome this shortcoming have been discussed elsewhere (Harms and Russell, 1993: Latshaw, 1997; Keshavarz, 1997). Recently, Penz and Jensen (1991) reported that the time of feeding of the low- and high-protein diets may be an important factor in using low-protein diets successfully in layer rations. When hens were fed a highprotein diet (16% protein) from 0400 to 0800 h and also Abbreviation Key: AP = available phosphorus; Exp. = experiments; SWUSA = shell weight per unit surface area; T = treatment. 1320
REDUCING PROTEIN, CALCIUM, AND PHOSPHORUS FOR LAYERS 1321 from 1400 to 2000 h and a low-protein diet (13% protein diet) from 0800 to 1400 h, egg production and egg weight were equivalent to hens of the control groups that continuously received the high-protein diet (16% protein). Other performance traits were not different among the control groups and the groups fed the altered protein regimen. However, the groups that were continuously fed the low-protein diet (13% protein) or fed the low-protein diet from 0400 to 0800 h and also from 1400 to 2000 h, and the high-protein diet from 0800 to 1400 h, produced significantly lower egg weights than hens of the control groups. These investigators hypothesized that the advantage of feeding the high-protein diet during the early hours of the day on egg weight was due to a greater need for protein during this period for albumen formation. The information from the study of Penz and Jensen (1991), however, was not adequate to determine whether the beneficial effect of feeding the high-protein diet during the early hours of the morning on egg weight was due to a higher daily protein intake by this group or was due to a higher protein intake when the majority of the hens had an egg in the magnum. However, their approach introduced a concept with the potential to satisfactorily reduce the protein level in laying hen diets. Based on the above information and the following rationale, we hypothesized that the requirement of laying hens, not only for protein, but also for phosphorus and calcium (among other nutrients), do not remain constant, but actually vary during different hours of the day, depending on physiological needs for these nutrients for formation of various components of eggs. Today s commercial strains of laying hens lay the majority of their eggs (about 90%) during the morning (Leeson and Summers, 1978). About 30 min after oviposition, the next ovulation takes place. It takes about 4 h for ovum to move from the infundibulum to the uterus (shell gland), with the majority of this time (3 to 3.5 h) spent in the magnum, where the egg white is formed and secreted. Thereafter, the ovum remains for about 18 to 20 h in the shell gland for shell deposition before the eggs are oviposited. The current commercial strains of laying hens have been selected for a high rate of egg production, and as a result, the time between two successive ovipositions is about 24 h or slightly greater particularly with younger hens. Although albumen and yolk have almost equal protein content, the proteins of the yolks are continuously synthesized in the liver and accumulated in the ovum until ovulation takes place (Morris and Taylor, 1967; Etches, 1996). On the other hand, the proteins of the albumen are synthesized in the oviduct and must be deposited on the ovulated ovum during a time period of 3 to 3.5 h while the ovum is in the magnum (Warren and Scott, 1935; Etches, 1996). According to Gilbert (1971) the bulk of the albumen proteins required for an egg are synthesized in the magnum between the passages of successive ova through the oviduct. Hiramoto et al. (1990) and Muramatsu et al. (1991) reported that the rate of protein synthesis in milligrams per hour per oviduct tissues were significantly increased when an ovum was in the magnum compared to when it was in the other segments of the oviduct. The results of a double label (3H/14C leucine) study of Shevchenko and Sherapanov (1986) indicated that about 70% of egg white protein is synthesized in the oviduct. These investigators suggested that the hen has a higher protein requirement during the morning, because it is exactly the time of extensive egg white protein synthesis for a majority of hens in their study. Failure of adequate protein synthesis in the magnum during this period may result in reduced egg white and egg size. Based on the aforementioned reasoning, it was logical to believe that the requirement for protein, at least for a majority of hens in a flock, would be greater during the morning hours when the ovum is anticipated to be in the magnum and egg white proteins are formed and secreted than during the afternoon and evening. On the other hand, shell is deposited around the albumen during the 18 to 20 h when the egg remains in the shell gland. The period of shell deposition coincides mainly with the afternoon and evening. Based on the above-mentioned reasoning, the requirement for Ca should be greater during the afternoon and evening, when shell calcification is taking place, than during the morning. In fact, several investigators reported that hens can regulate their daily Ca intake according to the need for shell formation (Taylor, 1970; Wood-Gush and Horne, 1971; Hughes, 1972; Leeson and Summers, 1997). Mongin and Sauveur (1974) reported that when hens are provided with a normal Ca diet (3.15%), the hourly intake of feed increased during the afternoon when shell calcification is in progress. When hens had ad libitum access to a low-ca diet (1%) and oyster shell, which were provided in separate feeders, the consumption of oyster shell increased substantially from 1600 to 2000 h, i.e., during the time that eggshell formation is in progress. Also, relative to the stage of egg formation, the voluntary intake of oyster shell increased sharply when the egg entered the shell gland. Clunies et al. (1992a, b) reported that feed, Ca, and P intake of hens increases on shell-forming days as compared with days on which shell formation does not take place. With regard to P, Roland and Harms (1976) reported that reducing the dietary P in the afternoon has beneficial effects on shell quality, whereas a converse approach has detrimental effects on shell quality, as compared to hens fed a diet with conventional level of P. Holcombe et al. (1975, 1976) presented information indicating that laying hens have the ability to regulate Ca and P intake according to their physiological need or anticipated need for these nutrients when they are given choice to consume diets with different concentrations of these minerals. They have shown that hens consume more P during the morning (0600 to 1400 h) than during the afternoon (1400 to 2000 h). The available information generally indicates that the current practice of providing the hens with one diet throughout the daily photoperiod might not be an ideal approach for optimum utilization of nutrients. Provid-
1322 ing the hens with one diet during the 16 h of daily photoperiod might result in wasteful use of nutrients due to either over-consumption of the nutrients at the time that the physiological need for the nutrients are minimal (such as high level of protein in the diet during the afternoon and evening hours) or over-consumption of feed for adequate intake of nutrients at the time that the need for nutrients are maximal (such as a greater need for Ca in the afternoon and evening). It has been shown that self-selection of nutrients results in a voluntary restriction of nutrient intake by laying hens (Leeson and Summers, 1978). These investigators reported that daily feed, energy, and protein consumption were reduced, and daily Ca intake was increased when hens were fed split-diets of high-energy, highprotein, and low-ca in the morning, and a diet with converse concentrations of these nutrients in the afternoon, as compared to hens fed a conventional layer diet. Production performance was not affected by dietary regimens used in their experiments. Furthermore, birds fed the split-diets had significantly greater carcass protein and significantly less carcass fat than those fed the conventional diet. The following experiments were conducted to determine whether the daily requirement of laying hens for protein, P, and Ca can be reduced by providing them with diets containing adequate levels of these nutrients only during those hours of the day when the physiological need for these nutrients for formation of various components of the egg are increasing. Although experiments under choice feeding conditions generally support this hypothesis, they may not apply under current commercial practices. Therefore, in conducting the current experiments, an approach was taken so that the results could have practical application. If the results of this study were successful, they could have the potential for diminishing the pollution problems associated with N and P excretion of poultry, and also would have the advantage of helping reduce feed costs involved in egg production. The results of the initial experiments are presented in this paper and the results of subsequent experiments are presented in an accompanying paper (Keshavarz, 1998). MATERIAL AND METHODS Protein Experiment Four hundred 30-wk-old pullets of a commercial Leghorn strain (Babcock B-300) were used. The pullets were housed five per shallow-designed cages (61 36 cm) in a high-rise environmentally controlled house. The pullets of four adjacent cages were considered an experimental replicate and each dietary treatment was fed to five replicates (100 hens per treatment). The composition of the 16 and 13% protein diets used in this experiment are shown in Table 1 (Diets 1 and 2, respectively). These diets were isocaloric and contained KESHAVARZ similar levels of linoleic acid and choline. The 16% protein diet contained all the nutrients to satisfy or exceed the NRC (1984, 1994) recommendations. The 13% protein diet was supplemented with methionine, lysine, isoleucine, and tryptophan to ensure adequate intake of these amino acids. The birds of T 1 (positive control) and T 2 (negative control) were fed the 16 and the 13% protein diets, respectively, throughout the 16 h of daily photoperiod (0500 to 2100 h). The birds of T 3 were fed the 16% protein diet during the morning (0500 to 1300 h), and the 13% protein diet during the afternoon (1300 to 2100 h). The birds of T 4 were fed the 13% protein diet during the morning and the 16% protein diet during the afternoon. Regardless of the dietary treatments, the morning and the afternoon feeds were delivered from two feed cans in order to determine feed consumption during the morning and the afternoon separately. The afternoon feeds were delivered at 1300 h every day. All leftover feed belonging to the afternoon was manually removed from the feeders immediately after the lights went off (2100 h) using a flashlight. The feeders were then filled with the morning feed during the dark hours (usually between 2100 to 2200 h) so that at lights on at 0500 h of the next morning, hens would have access to the morning feed. The morning feeds were replaced with the afternoon feeds at 1300 h. This cycle continued during the period of the experiment (30 to 38 wk of age). Daily egg production and weekly feed consumption were recorded during the experiment. All eggs produced during the last 3 d of every bi-weekly period (from 1300 of the 1st d to 1300 h of the 3rd d) were saved for the measurement of egg weight, grade (according to the USDA grading system), and specific gravity. A 20% random sample of eggs from each egg grade category was used for measurement of the egg components. Body weight was determined at the beginning and at the end of the experiment. At the termination of the experiment, one bird from each replicate that had a hard shell in the uterus (by palpation) was killed shortly after oviposition and the weight and the length of the different segments of oviduct was determined. Specific gravity was determined using salt solutions varying in specific gravity from 1.058 to 1.102 in increments of 0.004 units. Shell weight was determined after breaking the eggs and cleaning the shell from the adhering albumen using a paper towel. Yolk weight was determined after rolling the yolk on a damp paper towel to remove adhering albumen. Albumen weight was determined by subtracting the egg weight from the yolk plus shell weight. Phosphorus Experiment Four hundred pullets of the same strain and similar age as those used in the protein experiment were used in this experiment. The number of birds per replicate, the number of replicates per treatment, the period of the experiment, and the procedures for feeding the experimental diets and collecting performance and shell quality information were similar to those described for
REDUCING PROTEIN, CALCIUM, AND PHOSPHORUS FOR LAYERS 1323 TABLE 1. Composition of experimental diet, protein, and phosphorus experiments Diet 1 Diet 2 Diet 3 (16% protein (13% protein (16% protein Ingredients and analysis and 0.4% AP 1 ) and 0.4% AP) and 0.2% AP) (%) Corn 66.68 63.664 66.68 Barley... 11.5... Soybean meal, dehulled 20.764 11.8 20.764 Limestone 9.23 9.28 9.62 Mono-dicalcium phosphate 1.5 1.53 0.52 Salt 0.26 0.26 0.26 Vitamin mix 2 0.25 0.25 0.25 Mineral mix 3 0.15 0.15 0.15 Sodium bicarbonate 0.1 0.1 0.1 Blended fat 1 1 1 L-lysine HCl... 0.166... DL-methionine 0.066 0.166 0.066 Isoleucine... 0.085... Tryptophan... 0.02... Choline chloride, 60%... 0.029... Sand...... 0.59 Calculated analysis 4 Energy, kcal ME/kg 2,834 2,834 2,834 Protein 16 13 16 Lysine 0.82 0.7 0.82 Methionine 0.35 0.4 0.35 TSAA 0.6 0.6 0.6 Isoleucine 0.78 0.68 0.78 Tryptophan 0.2 0.17 0.2 Calcium 3.8 3.8 3.8 AP 0.4 0.4 0.2 Linoleic acid 1.76 1.75 1.76 Choline 5, mg/kg 1,201 1,202 1,202 1AP = available phosphorus. 2Vitamin premix provided per kilogram of diet: vitamin A (retinyl acetate), 8,800 IU; cholecalciferol, 2,200 IU; DL-a-tocopheryl acetate, 11 IU; menadione sodium bisulfite, 2.2 mg; riboflavin, 4.4 mg; D-calcium pantothenate, 8.8 mg; nicotinic acid, 44 mg; pyridoxine hydrochloride, 2.2 mg; folic acid, 0.55 mg; d-biotin,.11 mg; thiamine hydrochloride, 2.5 mg; vitamin B 12, 0.007 mg; choline chloride, 253 mg; ethoxyquin, 125 mg. 3Trace mineral premix provided per kilogram of diet: MnSO 4 H 2 O, 185 mg; ZnO, 62 mg; FeSO 4 7H 2 O, 149 mg; CuSO 4 5H 2 O, 19.6 mg; KI, 1.4 mg; Na 2 SeO 3, 0.22 mg. 4Based on NRC (1984) tables of feed composition. 5Including choline provided by vitamin mix. protein experiment. Diets 1 and 3 (Table 1) were used in this experiment. The composition of these diets were identical except that available P (AP) was reduced from 0.4% in Diet 1 to 0.2% in Diet 3 by reducing the level of mono-dibasic calcium phosphate and adjusting the levels of limestone and sand. The birds of T 1 and T 2 were fed 0.4% and 0.2% AP diets, respectively, during the 16-h photoperiod (0500 to 2100 h). The birds of T 3 were fed the 0.4% AP diet during the morning (0500 to 1300 h) and the 0.2% AP diet during the afternoon (1300 to 2100 h). The birds of T 4 were fed the 0.2% AP diet during the morning and the 0.4% AP during the afternoon. Experiments on the Pattern of Daily Feed Intake These trials were conducted concurrently. Two hundred young hens (27-wk-old) and 200 old hens (53- wk-old) were used in the first and the second trials, respectively. In each trial, birds were housed in groups of five hens per shallow-designed cages similar to those used in the previous experiments. Four adjacent cages were considered an experimental replicate and 10 replicates were considered for each trial. The period of these trials was 2 wk. In the third trial, 60 27-wk-old hens were used. The hens were housed in individual cages and the birds of 10 adjacent cages were considered an experimental replicate. Six replicates were considered for this trial. The period of the trial was 10 d. The hens in these trials were fed the Cornell layer-breeder diet for ad libitum consumption during the morning (0500 to 1300 h) and the afternoon (1300 to 2100 h). The feeding procedure was similar to the one described for the protein and P experiments. At the termination of these trials, the tests continued for an additional 48 h and feed consumption and egg production were recorded on 4-h basis during the photophase (0500 to 2100 h) and also during the 8-h scotophase (2100 to 0500 h). Calcium Experiment One hundred and twenty-five 42-wk-old hens were used in this experiment. The hens were housed in individual cages. The birds of five adjacent cages
1324 KESHAVARZ TABLE 2. Composition of experimental diets, Ca experiment Ingredients and analysis 2% Ca 3% Ca 3.08% Ca 3.8% Ca 5% Ca (%) Corn 62.4 62.4 62.4 62.4 62.4 Soybean meal, dehulled 21.6 21.6 21.6 21.6 21.6 DL-methionine 0.07 0.07 0.07 0.07 0.07 Salt 0.35 0.35 0.35 0.35 0.35 Limestone 4.62 7.25 7.46 9.36 12.52 Mono-dicalcium phosphate 1.16 1.16 1.16 1.16 1.16 Vitamin mix 1 0.25 0.25 0.25 0.25 0.25 Mineral mix 2 0.15 0.15 0.15 0.15 0.15 Blended fat 1.5 1.5 1.5 1.5 1.5 Sand 7.9 5.27 5.06 3.16... Calculated analysis 3 Energy, kcal ME/kg 2,750 2,750 2,750 2,750 2,750 Protein 16 16 16 16 16 Methionine 0.35 0.35 0.35 0.35 0.35 TSAA 0.6 0.6 0.6 0.6 0.6 Calcium 2 3 3.08 3.8 5 Available phosphorus 0.33 0.33 0.33 0.33 0.33 1Vitamin premix provided per kilogram of diet: vitamin A (retinyl acetate), 8,800 IU; cholecalciferol, 2,200 IU; DL-a-tocopheryl acetate, 11 IU; menadione sodium bisulfite, 2.2 mg; riboflavin, 4.4 mg; D-calcium pantothenate, 8.8 mg; nicotinic acid, 44 mg; pyridoxine hydrochloride, 2.2 mg; folic acid, 0.55 mg; d-biotin,.11 mg; thiamine hydrochloride, 2.5 mg; vitamin B 12, 0.007 mg; choline chloride, 253 mg; ethoxyquin, 125 mg. 2Trace mineral premix provided per kilogram of diet: MnSO 4 H 2 O, 185 mg; ZnO, 62 mg; FeSO 4 7H 2 O, 149 mg; CuSO 4 5H 2 O, 19.6 mg; KI, 1.4 mg; Na 2 SeO 3, 0.22 mg. 3Based on NRC (1984) tables of feed composition. consuming feed from the same feed trough were considered an experimental replicate and each dietary treatment was fed to five replicates for 6 wk. Five dietary treatments were used in this experiment. The Ca content of these diets were 2, 3, 3.08, 3.8, and 5% (Table 2). The experimental diets were isocaloric and isonitrogenous with similar levels of methionine, TSAA, and AP. Feeding procedures were similar to those described for the previous experiments. Body weight was determined at the beginning and at the end of the experiment. Daily egg production and weekly feed consumption were recorded throughout the experiment. Various indices of shell quality were measured on all eggs produced during the last 3 d of each biweekly period. The procedure for measurement of specific gravity was similar to that described for the protein experiment. Shell weight was determined after breaking eggs and cleaning shell from the adhering albumen and drying them in oven at 60 C. Shell weight per unit surface area (SWUSA) was determined using shell weight and surface area of each egg. The surface area of eggs was calculated according to approach of Ousterhout (1980). Shell thickness was measured on three pieces of shell from the equator of the egg with membranes intact using a micrometer. Data were analyzed by one-way analysis of variance (SAS Institute, 1988) and means were compared by Duncan s multiple range test (1955). RESULTS AND DISCUSSION Protein Experiment The objective of this experiment was to determine whether daily protein requirement of laying hens could be satisfactorily reduced by providing the hens with most parts of their daily protein need during the morning, which coincides with the time of albumen formation and secretion. The dietary regimens were selected with the assumption that hens consume approximately similar quantities of feed during the 8-h photoperiod in the morning (0500 to 1300 h) and the 8-h photoperiod in the afternoon (1300 to 2100 h). In contrast to our expectations, regardless of dietary regimen, about 40% of the daily feed intake was consumed during the morning and about 60% during the afternoon (Table 3). This pattern of feed intake remained consistent during every week throughout the experiment. Total daily feed intake for the entire experiment was not different among treatments, except that hens fed a 13% protein diet during both the morning and afternoon (T 2 ) had a lower total daily feed intake than hens of T 4, which were fed a 13% protein diet during the morning and a 16% protein diet during the afternoon (P < 0.05). Body weight gain and egg production performance were not different for hens continuously fed a 13% protein diet (T 2 ) and those fed a high-low protein (T 3 ) or a lowhigh protein (T 4 ) diets as compared to hens continuously fed a 16% protein diet (T 1 ) for the entire experiment (P > 0.05, Table 4). Due to the pattern of 40% feed consumption during the morning and 60% feed consumption during the afternoon, protein intake with each dietary treatment was considerably greater during the afternoon than the morning. As a result of this difference, it was not possible to determine whether production performance can be maintained satisfactorily when hens receive an adequate level of protein only during the morning, which coincides with the time of albumen formation and secretion and low protein level during the afternoon. The morning protein
REDUCING PROTEIN, CALCIUM, AND PHOSPHORUS FOR LAYERS 1325 ps7266 tab3 ps7266 tab4
1326 intake of birds of T 3 was very close to birds of T 1 ; however, the afternoon protein intake was considerably lower for the birds of T 3 than for the birds of T 1. The overall production performance of birds of these regimens (T 1 vs T 3 ) was not different. This result supports the hypothesis that providing the hens with an adequate protein level only during the morning can support optimum performance. Nevertheless, protein intake of birds of T 4 was significantly lower than the birds of T 3 during the morning (P < 0.05), but was greater than the birds of T 3 during the afternoon (P < 0.05). If adequate protein intake only during the morning was crucial, then one would expect to observe inferior performance for hens of T 4 than for the hens of T 3. However, the production performance of birds of T 3 and T 4 were not different (P > 0.05). The information obtained from this experiment suggests that optimum performance may be expected as long as the daily protein intake is adequate, regardless of whether maximum daily protein need occurs in the morning or the afternoon hours. Specific gravity was not different among various dietary regimens (P > 0.05). The weight or length of different segments of the oviduct were not influenced by protein regimens (Table 5). The only exception was the weight of the magnum, which was significantly heavier for hens continuously fed the 16% protein diets than for those continuously fed the 13% protein diets (T 1 vs T 2 ). Similar to egg weight for the entire experiment, the average weight of 20% eggs selected from each egg grade category for determining of egg components were not significantly different among different treatments (P > 0.05, Table 6). Egg components were not influenced by dietary regimens (P > 0.05). Phosphorus Experiment The objective of this experiment was to determine whether daily P requirement of laying hens can be satisfactorily reduced by providing the hens with most parts of their daily P need during the morning hours. In contrast to egg yolk, albumen has only a small quantity of P. Consequently, the rationale for conducting this experiment was not to provide the birds with most parts of their daily P need during the time that albumen formation and secretion are in progress. Rather, we were interested in determining whether shell quality, as suggested by Roland and Harms (1976), can be increased without affecting production performance by providing the hens with an adequate level of AP only during the morning hours. This approach could have the potential of reducing daily P requirements by providing the hens a low-p diet during the afternoon. This experiment was conducted concurrently with the protein experiment. Similar to the results of the protein experiment, regardless of dietary regimens, about 40% of the daily feed intake was consumed during the morning and 60% during the afternoon (Table 7). This pattern of feed consumption with small changes remained consistent every week during the experiment. Total daily feed consumption for the entire KESHAVARZ ps7266 tab5
REDUCING PROTEIN, CALCIUM, AND PHOSPHORUS FOR LAYERS 1327 TABLE 6. The effect of different protein regimens on egg components, protein experiment Protein level Egg components Morning 1 Afternoon 1 Egg weight 2 Yolk Albumen Shell (%) (g) (g) NS NS NS NS T 1 16 16 56.67 15.74 35.38 5.76 T 2 13 13 55.69 15.74 34.19 5.77 T 3 16 13 55.64 15.73 34.22 5.70 T 4 13 16 56.32 15.76 34.84 5.72 SEM 0.55 0.14 0.42 0.04 1Morning feeds were fed from 0500 to 1300 h and afternoon feeds were fed from 1300 to 2100 h. 2Average egg weight of 20% eggs from each egg grade category, which were used for determination of egg components. experiment was not different for hens continuously fed a diet with 0.2% AP (T 2 ), or hens fed the high-low (T 3 ) or the low-high (T 4 ) P diets, than the control group (T 1 ), which received a diet with 0.4% AP continuously during the morning and the afternoon. However, feed consumption tended to be lower for the hens continuously fed 0.2% AP diet (T 2 ) than the other treatments, although the differences were only significant between treatments of T 2 and T 3 (P < 0.05). Production performance and specific gravity were not different among different dietary regimens (Table 8). The only exception was body weight gain, which was lower (P < 0.05) for hens continuously fed 0.2% AP diet (T 2 ) than for hens fed the other dietary treatments. The daily AP intake for the entire experiment was about 200 mg per hen per d for hens fed the 0.2% AP diet continuously. Due to the loss of body weight, this level of AP intake appeared to be marginal to support optimum performance. On the other hand, daily AP intake of hens of high-low AP regimen (T 3 ) was 282 mg per hen per d for the entire experiment. This level of AP intake was sufficient to satisfy the requirement of laying hens during a period of high egg production. The hens of T 3 received a similar level of AP to those of T 1 during the morning, but with considerably lower AP intake than T 1 during the afternoon. The production performance of hens on these dietary treatments (T 1 vs T 3 ) were not different (P > 0.05). These results apparently support the hypothesis that the efficiency of P utilization may be improved and, as a result of this, the daily AP requirement may be reduced by providing the hens with an adequate level of AP only during the morning. However, no improvement in shell quality was observed due to intake of low AP level during the afternoon than the morning. On the other hand, birds of T 4 were receiving considerably lower AP than the birds of T 3 during the morning and about twice as much AP than the birds of T 3 during the afternoon. This increase in P intake during the afternoon as compared to morning did not have adverse effects on the shell quality of birds of T 4. The pattern of 40: 60% feed consumption during the morning and afternoon, prevented the appearance of a more severe reduction of P intake during the afternoon on shell quality. Nevertheless, similar to the results of the protein experiment, the information obtained from this experiment suggests that optimum production performance can be obtained as long as the daily P intake is adequate regardless of whether the maximum daily P need is during the morning or the afternoon. Experiments on Pattern of Daily Feed Intake These trials were conducted to examine the repeatability of the pattern of feed consumption observed in the protein and phosphorus experiments. The patterns of morning and afternoon feed consumption were consistent with the observations in the previous experiments indicating that hens consumed about 40% of their daily feed intake from 0500 to 1300 h and the next 60% from 1300 to 2100 h (Table 9). This pattern was consistent regardless of the hens ages or the numbers of birds per cage. The results of a subsequent 48-h test indicated that feed consumption with multiple hens per cage tended to be increased consistently as the time of day proceeded from 0500 to 2100 h (Table 10). However, such a distinct pattern was not apparent with individually caged hens, except that feed consumption was considerably greater during the afternoon, particularly during the last 4 h prior to lights off. The feed consumption during the dark period (2100 to 0500 h) was negligible and probably the small amount of feed intake was attributed to the time of changing the feed at 2100 h, although feed was changed during the dark period and a flashlight was used. The egg production data indicated that 97 to 98% of daily eggs were laid during the morning (0500 to 1300 h), and most parts of the remaining during the afternoon (1300 to 2100 h) with young hens (27-wk-old). With older hens (53-wkold) about 91% of the eggs were laid during the morning (0500 to 1300 h) and most parts of the remaining were laid during the afternoon (1300 to 2100 h). The number of eggs produced during the dark period (2100 to 0500 h) were negligible for young or old hens.
1328 KESHAVARZ ps7266 tab7 ps7266 tab8
REDUCING PROTEIN, CALCIUM, AND PHOSPHORUS FOR LAYERS 1329 TABLE 9. Pattern of daily feed intake with young and old hens housed in individual or multiple-hen cages Age at Hens per the start Period of Daily feed consumption Cage type cage of experiment experiment Morning Afternoon Total Morning Afternoon (no.) (wk) (d) (g) (%) Individual hens per cage 1 27 10 46.3 67.2 113.5 40.8 59.2 Multi-hens per cage 5 27 14 42.8 68.8 111.6 38.4 61.6 Multi-hens per cage 5 53 14 44.0 67.8 111.8 39.4 60.6 Average 44.4 67.9 112.3 39.5 60.5 Calcium Experiment We were interested to determine the reasons for higher feed consumption in the afternoon and evening than in the morning. The most logical reason to us was an increased appetite for Ca during these hours for shell formation. Consequently, the objectives of this experiment were to determine: 1) if the pattern of daily feed consumption can be changed by manipulation of Ca level in the morning and the afternoon feeds?; 2) if shell quality can be improved by providing most parts of the daily Ca need during the afternoon?; and 3) if the efficiency of Ca utilization can be improved, and as a result, the daily Ca need be reduced by providing an adequate level of Ca only during the afternoon? The rationale for selecting the dietary Ca levels for this experiment (Table 2) was as follows: We hypothesized that regardless of the levels of dietary Ca used in this experiment, birds still consume about 40% of their daily feed intake during the morning and 60% during the afternoon. The birds of T 1 served as the control group and were fed a diet containing 3.8% Ca both during the morning and the afternoon. The birds of T 2 were fed a diet with 2% Ca during the morning and 5% Ca during the afternoon. These dietary Ca levels were selected so that the birds of T 2 would receive most of the daily Ca intake TABLE 10. Feed consumption and egg production pattern of laying hens exposed to 16 h daylight, average of 2-d test Feed consumption 1Average of six replicates of 10 hens each ± SD. 2Average of ten replicates of 20 hens each ± SD. during the afternoon, i.e., the time that coincided with shell formation. We expected to observe better shell quality with birds of T 2 than T 1. Based on a pattern of 40% feed consumption during the morning and 60% during the afternoon, the daily total Ca intake of T 1 and T 2 was expected to be equal for a daily feed consumption of about 100 g per hen per d. The birds of T 3 served as a negative control for T 2 and were fed a diet with 5% Ca during the morning and 3% Ca during the afternoon. It was expected that most of the daily Ca intake would be consumed during the morning, but the total daily Ca intake of T 3 would remain equal to T 1 and T 2. Due to the possibility of palatability problems, the dietary Ca level in the morning feed of T 3 was not increased above 5%. It was anticipated that shell quality of birds of T 3 would remain inferior to birds of T 2 or T 1, because most of the daily Ca need was expected to be consumed during the morning, which did not coincide with the time of shell formation. Treatment 4 (T 4 ) was used to determine whether the efficiency of Ca utilization could be increased and as a result, the daily Ca need could be reduced by providing the hens with a similar Ca level to T 1 only during the afternoon (3.8%), but with a much lower level of Ca during the morning (2%). We expected to find similar shell quality for birds of T 4 and T 1, but the daily Ca requirement was expected to be Egg production 1 hen per cage 1 5 hens per cage 2 1 hen per cage 1 5 hens per cage 2 Time 28.5 wk old 29 wk old 55 wk old 28.5 wk old 29 wk old 55 wk old (g/hen) (%) 0500 to 0900 h 22.3 ± 2.4 19.5 ± 1.8 20.3 ± 1.2 58.3 ± 16.8 77.9 ± 9.1 33.8 ± 9.3 0900 to 1300 h 22.2 ± 1.4 26.8 ± 1.6 25.8 ± 1.5 38.4 ± 17.9 19.9 ± 8.8 57.4 ± 10.7 1300 to 1700 h 32.8 ± 2.4 31.5 ± 1.4 30.9 ± 1.6 3.3 ± 2.6 0.6 ± 1.2 7.0 ± 5 1700 to 2100 h 38.4 ± 1.8 41.1 ± 1.3 42.5 ± 2.5 0.0 ± 0.0 0.8 ± 1.8 1.5 ± 2.2 2100 to 0500 h 1.4 ± 0.2 1.0 ± 1.3 2.3 ± 0.6 0.0 ± 0.0 0.8 ± 1.3 0.3 ± 5.6 Total (0500 to 0500 h) 117.1 ± 5 119.9 ± 4.6 121.9 ± 1.6 100.0 100.0 100.0 0500 to 1300 h 38.0 ± 1.6 38.6 ± 1 37.9 ± 1.9 96.7 ± 2.6 97.8 ± 2.2 91.2 ± 5.6 1300 to 2100 h 60.8 ± 1.6 60.6 ± 0.9 60.2 ± 1.9 3.3 ± 2.6 1.4 ± 1.9 8.5 ± 5.4 2100 to 0500 h 1.2 ± 0.2 0.8 ± 0.4 1.9 ± 0.5 0.0 ± 0.0 0.8 ± 1.3 0.3 ± 5.6 (%)
1330 reduced only to 3.08 g for a daily feed consumption of about 100 g per hen per d. Treatment 5 (T 5 ) served as a control for T 4 and birds of this treatment were fed a diet with 3.08% Ca during the morning and the afternoon. Although the daily Ca intake was expected to be equal among the birds of T 5 and T 4, we anticipated better shell quality with T 4 than T 5, because most parts of the daily Ca need was expected to be consumed during the afternoon by birds of the T 4. Regardless of dietary Ca levels, birds consumed about 40% of their daily feed intake during the morning and about 60% of their daily feed intake during the afternoon (Table 11). These results do not confirm the notion that the greater feed intake during the afternoon than the morning may be due to an increased appetite for Ca for shell formation. If this were the case, then one would expected to see reduced feed consumption with T 2 during the afternoon because of the presence of the abundance of Ca in the diet during this period. Morning feed consumption was lower for birds of T 3 than birds of T 1 (P < 0.05), although the daily feed consumption was not different among these treatments. Apparently increasing the dietary Ca to 5% had some deleterious effect on feed consumption during the morning but not during the afternoon (T 2 vs T 3 ). Although, some differences in egg production and egg weight were observed among various treatments, egg mass, which is the product of these traits, was not different among dietary regimens. Feed conversion of birds of T 3 was superior to the other dietary treatments. Body weight gain was slightly but significantly lower for hens of T 5 than T 1 (P < 0.05). Birds of T 2 consumed significantly more Ca during the afternoon and less Ca during the morning than the birds of T 1 (P < 0.05, Table 12). However, the total daily Ca intake was not different between these treatments. The greater Ca intake of the birds fed T 2 as compared to birds of T 1 during the afternoon did not have a beneficial effect on various indices of shell quality. On the other hand, birds of T 3 received significantly more Ca during the morning and less Ca during the afternoon than the birds of T 1 and T 2 (P < 0.05). The total daily Ca intake was slightly, but significantly, lower for the birds of T 3 than T 1. These differences in the pattern of morning and afternoon Ca intake of birds of T 3 as compared to birds of T 1 and T 2 did not have an adverse effect on various indices of shell quality (T 3 vs T 1 or T 2 ). In fact, shell weight was slightly, but significantly greater for birds fed T 3 than T 1. Birds of T 4 received significantly more Ca during the afternoon and less Ca during the morning than birds of T 5. Again, the higher afternoon Ca intake of birds of T 4 as compared to T 5 did not have a beneficial effect on various indices of shell quality. Total daily Ca intake was not different among the birds of T 4 and T 5, but was significantly lower than the other dietary treatments. Indices of shell quality were not different among the birds of T 4 and T 5 or among these groups and the birds of T 1 ; however, some of the indices of shell quality of birds KESHAVARZ ps7266 tab11
REDUCING PROTEIN, CALCIUM, AND PHOSPHORUS FOR LAYERS 1331 TABLE 12. The effect of variation of daily calcium intake on shell quality, Ca experiment Ca in the diet Ca intake Shell quality Morning 1 Afternoon 1 Morning Afternoon Total Specific gravity Shell weight Percentage shell Shell thickness SWUSA (%) (g/hen/d) (g) (%) (mm) (mg/cm 2 ) T 1 3.8 3.8 1.87 b 2.6 b 4.47 a 1.0775 ab 5.55 b 9.33 0.378 ab 78.1 T 2 2 5 0.92 d 3.42 a 4.34 ab 1.0787 a 5.61 ab 9.42 0.384 a 78.8 T 3 5 3 2.21 a 2.04 c 4.25 b 1.0786 a 5.76 a 9.45 0.386 a 79.7 T 4 2 3.8 0.96 d 2.69 b 3.65 c 1.0766 b 5.62 ab 9.27 0.379 ab 78.0 T 5 3.08 3.08 1.42 c 2.09 c 3.51 c 1.0765 b 5.61 ab 9.24 0.372 b 77.7 SEM 0.04 0.06 0.12 0.0006 0.06 0.1 0.003 0.7 a dmeans within columns with no common superscript differ significantly (P < 0.05). 1Morning feeds were fed from 0500 to 1300 h and afternoon feeds were fed from 1300 to 2100 h. fed T 4 or T 5 were lower than for birds fed T 2 or T 3. This effect might have been due to a lower daily Ca intake of birds of the former than the latter groups. This study generally failed to indicate that providing most parts of the daily Ca need during the afternoon has a beneficial effect on shell quality. Comparing shell quality indices of birds of T 1 with those of T 4 indicated that the daily Ca requirement may be reduced by providing adequate Ca only during the afternoon. The results of protein and P experiments were inconclusive. In both experiments, the pattern of 40% feed consumption during the morning and 60% feed consumption during the afternoon reduced the sensitivity of the experiments. Additionally, the level of protein and AP of the negative controls in these experiments were not low enough to result in producing significant adverse effects on performance. The results of the Ca experiment failed to indicate that the higher feed consumption during the afternoon was due to an increased appetite for Ca during this period for shell formation. The Ca experiment also failed to indicate that providing most parts of the daily Ca intake during the afternoon and evening as compared to the morning has a beneficial effect on shell quality. Further experiments on the pattern of daily feed intake and more detailed experiments pertaining to dietary protein, P, and Ca levels during the morning and the afternoon are required to reach to decisive conclusions. These were the subject of experiments presented in a companion paper (Keshavarz, 1998). REFERENCES Calderon, V. M., and L. S. Jensen, 1990. The requirement for sulfur amino acid by laying hens as influenced by protein concentration. Poultry Sci. 69:934 944. Clunies, M., D. Parks, and S. Leeson, 1992a. Calcium and phosphorus metabolism and eggshell formation of hens fed different amounts of calcium. Poultry Sci. 71:482 489. Clunies, M., D. Parks, and S. Leeson, 1992b. Calcium and phosphorus metabolism and eggshell thickness in laying hens producing thick or thin shells. Poultry Sci. 71:490 498. Duncan, D. B., 1955. Multiple range and multiple F-test. Biometrics 11:1 42. Etches, R. J., 1996. Chapter 7. Egg Formation in: Reproduction in Poultry. CAB International. University Press, Cambridge, UK. Gilbert, A. B., 1971. Transport of the egg through the oviduct and oviposition. Pages 1345 1352 in: Physiology and Biochemistry of the Domestic Fowl. Vol. 3. D. J. Bell and B. M. Freeman, ed. Academic Press, London, UK. Harms, R. H., and G. B. Russell, 1993. Optimizing egg mass with amino acid supplementation of a low-protein diet. Poultry Sci. 72:1892 1896. Hiramoto, K., T. Muramatsu, and J. Okumura, 1990. Protein synthesis in tissues and in the whole body of laying hens during egg formation. Poultry Sci. 69:264 269. Holcombe, D. J., D. A. Roland, Sr., and R. H. Harms, 1975. The ability of hens to adjust calcium intake when given diets containing two levels of calcium. Poultry Sci. 54:552 561. Holcombe, D. J., D. A. Roland, Sr., and R. H. Harms, 1976. The ability of hens to regulate phosphorus intake when offered diets containing different levels of phosphorus. Poultry Sci. 55:308 317. Hughes, B. O., 1972. A circadian rhythm of calcium intake in the domestic fowl. Br. Poult. Sci. 13:485 493. Jensen, L. S., V. M. Calderon, and C. X. Mendonca, Jr., 1990. Response to tryptophan of laying hens fed practical diets varying in protein concentration. Poultry Sci. 69:1956 1965. Keshavarz, K., N. M. Dale, and H. L. Fuller, 1980. The use of nonprotein nitrogen compounds, sugar beet molasses and their combinations in the growing chicks and laying rations. Poultry Sci. 59:2492 2499. Keshavarz, K., 1984. The effect of different dietary protein levels in the rearing and laying periods on performance of White Leghorn chickens. Poultry Sci. 63:2229 2240. Keshavarz, K., 1986. The effect of protein levels in pre- and postpeak production periods on performance of laying hens. Nutr. Rep. Int. 34:473 487. Keshavarz, K., 1997. Investigations on the use of low-protein, amino acid-supplemented diets for poultry. Pages 155 163 in: Proceedings Cornell Nutrition Conference, Rochester, NY. Keshavarz, K., 1998. Further investigations on the effects of dietary manipulation of protein, phosphorus, and calcium for reducing the daily requirement of laying hens. Poultry Sci. 77:1333 1347. Keshavarz, K., and M. E. Jackson, 1992. Performance of growing pullets and laying hens fed low-protein, amino acidsupplemented diets. Poultry Sci. 71:905 918.
1332 KESHAVARZ Latshaw, D., 1997. A comparison of the isoleucine and lysine requirements in laying hen diets. Poultry Sci. 76(Suppl. 1):62. (Abstr.) Leeson, S., and L. J. Caston, 1996. Response of laying hens to diets varying in crude protein and available phosphorus. J. Appl. Poult. Res. 5:289 296. Leeson, S., and J. D. Summers, 1978. Voluntary food restriction by laying hens mediated through dietary self-selection. Br. Poult. Sci. 19:417 424. Leeson, S., and J. D. Summers, 1997. Chapter 4. Feeding Programs for Laying Hens in: Commercial Poultry Nutrition. 2nd ed. University Books, Guelph, ON, Canada. Mongin, P., and B. Sauveur, 1974. Voluntary food and calcium intake by the laying hens. Br. Poult. Sci. 15:349 359. Morris, B. A., and T. G. Taylor, 1967. The daily food consumption of laying hens in relation to egg formation. Br. Poult. Sci. 8: 251 257. Muramatsu, T., K. Hiramoto, and J. Okumura, 1991. Changes in ovalbumin and protein synthesis in vivo in the magnum of laying hens during the egg production cycle. Comp. Biochem. Physiol. 99B:141 146. National Research Council, 1994. Nutrient requirements of poultry. 9th rev. ed. National Academy Press, Washington, DC. National Research Council, 1984. Nutrient requirements of poultry. 8th rev. ed. National Academy Press, Washington, DC. Ousterhout, L. E., 1980. Effect of calcium and phosphorus level on egg weight and shell quality in laying hens. Poultry Sci. 59:1480 1484. Penz, A. M., Jr., and L. S. Jensen, 1991. Influence of dietary protein concentration, amino acid supplementation, and daily time of access to high- and low-protein diets on egg weight and egg components in laying hens. Poultry Sci. 70: 2460 2466. Roland, D. A., Sr., and R. H. Harms, 1976. The influence of feeding diets containing different calcium-phosphorus ratios on laying hens. Poultry Sci. 55:637 641. SAS Institute, 1988. SAS/STAT User s Guide, Release 6.03 Edition. SAS Institute Inc., Cary, NC. Shevchenko, V. G., and G. G. Sherapanov, 1986. Evaluation of the egg protein synthesis dynamics in the oviduct of laying hens. Sel Skokhozyaistvennaya Biologiva. No. 7: 110 114. Summers, J. D., J. L. Atkinson, and D. Spratt, 1991. Supplementation of a low protein diet in an attempt to optimize egg mass output. Can. J. Anim. Sci. 71:211 220. Summers, J. D., 1993. Reducing nitrogen excretion of the laying hen by feeding lower crude protein diets. Poultry Sci. 72: 1473 1478. Taylor, T. G., 1970. The provision of calcium and carbonate for laying hens. Pages 108 128 in: Proceedings of 4th Nutrition Conference of Feed Manufacturers. H. Swan and D. Lewis, ed. Churchill, London, UK. Warren, D. C., and H. M. Scott, 1935. The time factor in egg formation. Poultry Sci. 14:195 207. Wood-Gush, D.G.M., and A. R. Horne, 1971. The effect of egg formation and laying on the food and water intake of Brown Leghorn hens. Br. Poult. Sci. 11:459 466.