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The Effects of Dietary Nutrient Concentration, Crumbles Versus Mash and Age of Dam on the Growth of Broiler Chicks
The Effects of Dietary Nutrient Concentration, Crumbles Versus Mash and Age of Dam on the Growth of Broiler Chicks J. N. AUCKLAND AND R. B. FULTON Loughry College of Agriculture and Food Technology, Cookstown, N. Ireland (Received for publication March 6, 1972)
POULTKY SCIENCE 51: 1968-1975,
INTRODUCTION EVERAL reports indicate that chicks consume more food and grow faster when fed pellets or crumbles than when the same diets are fed as mash. Part of the growth response may be due to chemical changes during the pelleting process (Allred et al., 1956). This might involve destruction of growth inhibitors and breakdown of food components during heat treatment, although Bolton (1960) showed that the chemical composition and digestibility of the diet was not affected by pelleting. In another case the increase in growth rate obtained was apparently entirely due
S
1972
to an increase in voluntary food intake with pelleted diets (Hamm and Stephenson, 1959). Thus the growth response to pellets or crumbles seems to be largely or in some cases entirely due to an increase in food consumption. Therefore an increase in energy and protein intake, which might be induced by raising the concentration of these nutrients in a mash diet, may reduce or eliminate the growth response from crumbling at higher dietary nutrient levels. Such an interaction between dietary nutrient concentration and method of preparing feed was demonstrated with turkey poults by Pepper et al. (1960). This paper reports
1968
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ABSTRACT Two experiments were conducted to determine the effect of dietary nutrient concentration on the growth response to crumbles compared with mash in broiler starter diets. In the first experiment four diets with similar calorie: protein ratios and calculated energy levels of 2866, 2979, 3090 and 3205 kcal. M.E./kg. were fed ad libitum, as mash and as crumbles, to broiler chicks of mixed sex from 0 to 2 weeks of age. Biological determinations of metabolizable energy were done for the highest and lowest energy diets. These were in good agreement with calculated values. Determined values for crumbles were about one percent higher than corresponding values for mash. Differences between growth increments in favour of crumbles compared with mash were 35, 17, 11 and 9 percent as dietary nutrient concentration increased. With mash, growth rate increased by about 11, 4 and 2 percent for successive increases in dietary nutrient concentration. When the same diets were fed as crumbles no positive response was obtained and the lowest energy diet supported maximum growth. This experiment therefore demonstrated an interaction between dietary nutrient concentration and method of preparing feed. In the second experiment a third variable was introduced, body weight at day-old as influenced by age of dam when hatching eggs were laid, because it was considered that this would affect food intake and might influence the growth response to crumbles. In this experiment the highest and lowest energy diets were fed, as mash and as crumbles, to male chicks from 0 to 4 weeks of age. Half the chicks were obtained from younger dams and average body weight at day-old was 37g. The other half was obtained from older dams and their day-old weight was 44g. There were no significant interactions between dietary nutrient concentration, method of preparing feed and age of dam when hatching eggs were laid, for liveweight gain in the 0 to 4 week period. On average, chicks fed crumbles grew 9 and 6 percent faster than those fed mash, on the lower and higher energy diets respectively. Chicks ate more calories and grew faster on the higher compared with the lower energy diet. In the 0 to 4 week period chicks from older dams ate more food and grew significantly faster than chicks from younger dams. All groups were then fed the same pelleted grower diet from 4 to 8 weeks of age. Differences in early growth rate due to dietary nutrient concentration, crumbles versus mash and age of dam, were no longer apparent by 8 weeks of age.
ENERGY LEVELS AND CRUMBLES
two experiments designed to test this possibility with broiler chicks. In addition a third variable, body weight at day-old as influenced by age of dam when hatching eggs were laid, was introduced in the second experiment. Because it was considered that this would affect food intake and might influence the growth response to crumbles.
A total of 480 Ross broiler chicks were used in each experiment. These were of mixed sex in experiment 1 and males in experiment 2. In experiment 1 chicks were weighed at day-old and allocated at random to 32 groups of IS chicks in electrically heated battery brooders. Four groups were assigned at random to each of eight treatments. These consisted of 4 diets, each fed ad libitum as mash and as crumbles, from 0 to 2 weeks of age (1 January to 14 January, 1971). In experiment 2 the 480 day-old males, which were all hatched on the same day, consisted of 240 lighter chicks obtained from younger dams which were 31 weeks of age when hatching eggs were laid, and 240 heavier chicks from older dams of 54 weeks of age when eggs were laid. Within each of these categories, four groups of 15 chicks each were assigned at random to each of four feeding treatments in the same electrically heated battery brooders used in experiment 1. The feeding treatments consisted of two diets fed ad libitum as mash and as crumbles from 0 to 4 weeks of age (29 June to 27 July, 1971). At 4 weeks of age the four groups in each treatment were transferred and mixed in one of eight floor pens. All the birds in the experiment were then fed the same commercial pelleted diet from 4 to 8 weeks of age. This was to determine whether treatment differences in liveweight at day-old and at 4 weeks were maintained to market age.
MASH
1969
The experimental starter diets used in both experiments are shown in Table 1. The four diets were computer formulated by specifying energy levels calculated to increase in approximately equal steps from 2866 to 3205 kcal.M.E./kg. For each energy level appropriate minimum values were specified for 13 essential amino acids and calcium and phosphorus. Total protein was minimised to reduce unwanted surpluses of amino acids. Calorie:protein, calorie methionine and calorie:lysine ratios were calculated to be similar in each diet. However the calorie:protein ratios shown in Table 1 vary somewhat, because they were estimated using determined rather than calculated values for crude protein and in some cases for metabolizable enery. The diet fed to all groups in the 4 to 8 week period in experiment 2 was a proprietary compound estimated to support maximum growth at that stage. An amount of each of the four starter diets was mixed sufficient for experiment 1, but further mixing was necessary for the two starter diets used in experiment 2 (diets 1 and 4). Crude protein determinations were made on each mash mixture. In the case of the two diets 1 and 4, which were used in both experiments, crude protein determinations were in reasonable agreement for the two mixes and average values are therefore shown in Table 1. Determined crude protein values were 1 to 2 percentage points higher than calculated levels. Crumbles were made from pellets prepared using 6 mm. dies, after the mash had been exposed to a steam-heating process. As a check on the figures calculated using book values, biological determinations of metabolizable energy were done for diets 1 and 4 as mash and crumbles separately (see Table 1). Determinations were carried out by the total collection method over a 4 day period. This was not done on individuals. Instead, each diet was fed to a group of five 4 week old
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on May 24, 2015
MATERIALS AND METHODS
versus
1970
J. N. AUCKLAND AND R. B. FULTON TABLE 1.—Composition of starter diets 1
2
3
4
Maize Wheat Barley Soyabean meal Fish meal Groundnut oil Dried grassmeal DL-Methionine (98%) L-Lysine HC1 (97%) Limestone flour Dicalcium phosphate Salt Vitamins and trace minerals*
12.00 35.80 28.70 9.10 8.00 0.90 3.50 0.084 0.130 0.385 0.885 0.090 0.620
20.00 35.30 20.50 8.50 10.00 1.50 2.50 0.072 0.093 0.324 0.730 0.090 0.620
28.00 34.70 12.30 7.90 12.00 2.10 1.50 0.060 0.055 0.263 0.576 0.090 0.620
36.00 34.20 4.10 7.30 14.00 2.70 0.50 0.048 0.018 0.202 0.421 0.090 0.620
100
100
100
Calculated and determined analyses Mash Crumbles Calculated M.E., kcal./kg. Determined M.E., kcal./kg. 1 Calculated crude protein % Determined crude protein % 2 Calorie:protein ratio 3 Methionine % Methionine-(- cystine % Lysine % Calcium % Available phosphorus %
2866 2865 145
2979
146
Crumbles
Mash 3205
3090
2896 17.9 19.8 145 0.42 0.74 1.04 0.96 0.54
100
3300
3267 18.6 20.6 145 0.44 0.77 1.09 1.00 0.56
19.3 21.0 147 0.46 0.79 1.13 1.04 0.58
154
20.0 21.2 151 0.48 0.81 1.17 1.08 0.60
156
1 Each value was obtained using figures for total food intake and total droppings of 5 chicks over a 4 day period. 2 By kjeldahl analysis of mash diets. 3 Kcal. M.E./kg.^percent crude protein by kjeldahl. * Amounts furnished per kg. of diet—Vitamins: Vit. A 110001.U.; Vit. D 3 6001.U.; Vit. Ki 2.0 mg.; Ca pantothenate 9.8 mg.; niacin 9.8 mg., Choline CI 1326 mg.; Vit. Bi2 5.0 meg.; Folic acid 490 meg.; Vit. E 6 I.U. Trace minerals: copper sulphate 19 mg.; Iron sulphate 146 mg.; Zinc oxide 61 mg.; Manganese sulphate 69 mg.; Potassium iodide 1.3 mg.; Cobalt sulphate 2.4 mg.
chicks. Total food consumed and total droppings of each group were then used for the estimation of metabolizable energy. For diet 1 the determined value for mash was virtually identical to the figure calculated using book values, and the value for crumbles was about 1 percent higher. For diet 4, the determined value for mash was in reasonable agreement with the calculated value. And again the value for crumbles was about 1 percent higher than for mash. RESULTS
Experiment 1. Growth: Results of experiment 1 are shown in Table 2. Average body
weight at day-old was 41 g. per chick. Chicks fed crumbles grew faster than corresponding groups fed the mash diets. But differences in growth increments in favour of crumbles were greater at the lower than at the higher dietary nutrient levels—50, 27, 18 and IS g. per chick for diets 1, 2, 3 and 4 respectively. This interaction between dietary nutrient concentration and method of preparing feed approached significance at P = 0.05. With the mash diets growth rate increased by 11, 4 and 2 percent with successive increases in dietary nutrient concentration. This response suggests that the highest energy diet promoted near to the maximum growth rate possible
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Diet No.
ENERGY LEVELS AND CRUMBLES
with mash. When the same diets were fed as crumbles no positive response was obtained and the lowest energy diet was evidently adequate for maximum growth of these chicks.
versus
TABLE 2.—Results of Experiment 1 Treatment Code1
0.1421
IC
0.192J
0.167
Mortality 0-2 weeks, percent 6.7]
o.oj
3.3
2C
0.1571 (0.170 0.184J
0.01 1-3.3 6.7J
3M
0.1641
3C
0.182J
0.01 }0.8 1-7 J
4M
0.1671 (0.174 0.182)
5.0)
4C S.E. of each mean Least significant difference (P=0.05)
to. 173
1.71 (3.3
0.006 0.005 0.019 0.013
1
1, 2, 3, 4=diet numbers (see Table 1); M=mash, C = crumbles. 2 Liveweight less day-old weight.
tirely due to differences obtained for the lighter chicks. Since with heavier chicks from older dams the difference in growth rate in favour of crumbles was similar for each dietary energy level. The data for body weight at 8 weeks are also shown in Table 3. Least significant differences cannot be given since the 4 groups in each treatment were mixed together in one floorpen after 4 weeks of age. But the data strongly suggest that differences in early growth rate, in favour of chicks fed the higher energy starter diet, and in favour of crumbles rather than mash, were no longer apparent at 8 weeks of age. Similarly, early difference in favour of chicks from older dams had also disappeared by the 8 week stage. Unfortunately it could not be determined which treatment had the best overall feed efficiency, since food consumption in the 4 to 8 week period was not recorded. Food consumption: There were no significant treatment interactions for food consumption in the 0 to 4 week period (Table 4). On average, chicks fed the higher energy diet ate a similar amount of food and therefore considerably more calories and protein than groups fed the lower energy
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Experiment 2. Growth: Results of experiment 2 are shown in Tables 3 and 4. There were no significant interactions between dietary nutrient concentration, method of preparing feed and age of dam when hatching eggs were laid, for liveweight gain in the 0 to 4 week period (Table 3). On average, chicks fed the higher energy diet grew significantly faster than groups fed the lower energy diet. Chicks fed crumbles grew faster than those fed mash. Chicks from older dams were significantly heavier at one day of age and grew significantly faster than chicks from younger dams. Average growth increments were 0.577 and 0.S48 kg./bird for chicks from older and younger dams respectively. Although there were no significant interactions, there was a tendency for the growth response to crumbles to be smaller with the higher energy diet. Thus on average, chicks fed crumbles grew nearly 9 percent faster than those fed mash with the low energy diet. And with the higher energy diet, chicks fed crumbles grew nearly 6 percent faster than those fed mash (Table 3). And this tendency for the average growth response to crumbles to be less with the higher energy diet was en-
Liveweight gain2 0-2 weeks, kg./bird
IM
2M
Food consumption: Because of an error in recording food consumption in this experiment, the data for food consumption, nutrient intake and food conversion ratios are omitted. Mortality: There were no consistent differences in mortality due to dietary nutrient level but on the average mortality was greater for chicks fed crumbles than for those fed mash (Table 2).
1971
MASH
1972
J. N. AUCKLAND AND R. B. FULTON
Feed conversion ratios: The only significant interaction for feed conversion ratios in the 0 to 4 week period was between dietary nutrient concentration and age of dam (P = 0.05). This indicated that the faster-growing chicks from older dams had a similar or slightly more efficient feed conversion ratio on the lower energy diet but a somewhat poorer feed conversion ratio on the higher energy diet (Table 4). This was due to small and opposite differences in growth rate and feed consumption. Thus chicks from older dams ate about 5 percent more feed and grew about 7 percent faster than those from younger dams on the lower energy diet. But they ate about 9 percent more and grew only 4 percent faster on the higher energy diet (Tables 3 and 4). On average, feed conversion was significantly more efficient for chicks fed the higher compared with the lower energy diet (P = 0.001). Average feed conversion was marginally more efficient for chicks fed crumbles compared with those fed mash.
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diet. This indicated a marked inability to adjust food intake in response to changes in dietary nutrient concentration in this range. Chicks fed crumbles ate more food than those fed mash. Chicks from older dams ate more food than those from younger dams. Average food intake in the 0 to 4 week period was 38.5 and 36.0 g./bird day for chicks from older and younger dams respectively. These results for food consumption are consistent with the average growth responses obtained. Although there was no significant interaction, chicks fed crumbles ate on average about 7 percent more than those fed mash with the lower energy diet, whereas the corresponding increase was barely 5 percent with the higher energy diet (Table 4). This is consistent with the tendency for the growth response to crumbles to be somewhat smaller with the higher energy diet.
ENERGY LEVELS AND CRUMBLES
Mortality: On average, mortality was similar for chicks fed crumbles and those fed mash. Average mortality for chicks which were heavier at day-old and came from older dams was 3.3 percent, and for chicks from younger dams it was 3.9 percent. Mortality was lower for chicks fed the higher compared with the lower energy diet in this experiment (Table 3).
1973
MASH
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DISCUSSION Effect of age of dam when hatching eggs were laid. In spite of the lack of significant interactions in experiment 2, growth responses to crumbles and dietary nutrient concentration did tend to differ somewhat for the heavier and lighter chicks from older and younger dams. Increase in growth rate in the 0 to 4 week period, due to crumbles compared with mash, was similar for heavier and lighter chicks fed the lower energy diet. But with the higher energy diet it was 51 g. per chick for those from older dams and only 16 g. per chick for those from younger dams. For the heavier chicks the growth advantage in favour of crumbles was similar at each dietary energy level studied. Whereas for lighter chicks from younger dams the difference in favour of crumbles was 43 g. per chick on the lower energy diet and only 16 g. per chick on the higher energy diet. These tendencies for differences in response to dietary treatments, due to body weight at day-old, warrant further investigation. Differences in body weight at day-old due to age of dam when hatching eggs were laid, were still in evidence at 4 weeks but had apparently disappeared by 8 weeks of age. This is in general agreement with other investigations using both chicks and poults, which showed that the influence of egg size or body weight at hatching upon subsequent body weight was only apparent for a few weeks. Correlations between hatching weight and body weight at 8 or 12
versus
1974
J. N. AUCKLAND AND R. B. FULTON
weeks of age were insignificant and approached zero (Godfrey et al., 1953; Asmundson and Pun, 1954).
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Effect of dietary nutrient concentration on the response to crumbles. In both experiments chicks offered crumbles grew faster than when the same diets were fed as mash, In experiment 1 the growth response to crumbles decreased markedly and progressively as dietary nutrient concentration was increased. Chicks fed crumbles grew 35 and 9 percent faster than those fed mash, with the lowest and highest energy diets respectively. In experiment 2 dietary nutrient concentration had a less marked effect on the response to crumbles. On average, chicks fed crumbles grew about 9 and 6 percent faster than those fed mash, on the lower and higher energy diets. Giirocak (1971) found that growth of broilers in the 0 to 8 week period was 7.4 and 6.9 percent faster with pellets than with mash on low and higher energy diets respectively. This seems to support the smaller influence of dietary energy level on the growth response to crumbles obtained in the second experiment. However, the different age intervals considered (0-2 weeks experiment 1 and 04 weeks in experiment 2) and/or sex differences (mixed sex in experiment 1 and males in experiment 2) could conceivably have been responsible for this difference in magnitude of interaction in the two experiments. Growth responses to crumbles were of comparative magnitude for chicks fed the higher energy diet in the two experiments —nine percent in experiment 1 and six percent in experiment 2. It was at the lower dietary nutrient concentration where the response to crumbles was considerably greater in the first experiment. This difference between the two experiments cannot be adequately explained. It seems likely to be a reflection of differences in voluntary
food intake. The growth data for experiment 1 suggest that chicks were unable to adjust food intake, as nutrient concentration was lowered in the more bulky mash diets, with the result that chicks fed the lowest energy diet as mash probably ate an inadequate amount of calories and protein and therefore grew slowly. Whereas with crumbles voluntary food intake was apparently precisely adjusted so as to maintain a similar nutrient intake, as suggested by the similar growth rates obtained on the lowest and highest energy diets. Consequently there was a large growth advantage from feeding crumbles as opposed to mash with the lowest energy diet. In experiment 2 on the other hand, chicks fed crumbles were for some reason only slightly less inefficient than chicks fed mash at adjusting food intake in response to changes in dietary nutrient concentration. Thus with mash there was zero adjustment in the sense that voluntary food intake was identical for the lower and higher energy diets. With crumbles, food consumption was only about 2 percent greater and calorie intake consequently about 8 percent less, on the lower energy diet (see Table 4). However, in both experiments the growth response to crumbles did decrease as dietary nutrient concentration increased. In both cases there was still a growth advantage of 6 to 9 percent in favour of crumbles even with the highest energy diet fed. Although it is possible that a dietary energy concentration greater than 3.3 kcal. M.E./g. might have further reduced or even eliminated the growth responses to crumbles which were obtained. On the other hand it seems likely that a small amount of extra growth, probably mainly as extra body fat, may be obtained from crumbles as opposed to mash even at higher dietary energy levels and calorie intakes. Because determined metabolizable energy values were about 1 percent higher
ENERGY LEVELS AND CRUMBLES
MASH
1975
celerating. Since by definition this means that growth rate at any point in this phase tends to be proportional to growth already made or body weight to which it is being added (Brody, 1926). Thus a nutrition induced weight advantage at 4 weeks of age should theoretically be increased, or at least maintained at the same absolute level, to 8 weeks of age. REFERENCES Allred, J. B., L. S. Jensen and J. McGinnis, 1956. Studies on the growth promoting effect induced by pelleting feed. Poultry Sci. 35: 1130. Asmundson, V. S., and C. F. Pun, 1954. Growth of Bronze turkeys. Poultry Sci. 33 : 981-986. Bolton, W., 1960. The digestibility of mash and pellets by chicks. J. Agric. Sci. 55: 141-142. Brody, S., 1926. Growth and development with special reference to domestic animals, iii. Growth rates, their evaluation and significance. Missouri Agric. Exp. Sta. Bull. No. 97. Godfrey, G. F., C. Williams and C. E. Marshall, 1953. The relative influence of egg size, age at sexual maturity and mature body weight on growth to 12 weeks of age. Poultry Sci. 32 : 496-500. Giirocak, L., 1971. Investigations concerning the influence of pelleting broiler rations on the performance. World Poultry Sci. J. 27: 174-175. Hamm, D., and E. L. Stephenson, 1959. The pelleting response in broiler feeding. Poultry Sci. 38: 1211. Pepper, W. F., S. J. Slinger and J. D. Summers, 1960. Studies with chickens and turkeys on the relationship between fat, unidentified factors and pelleting. Poultry Sci. 39: 66-74. Reddy, C. V., L. S. Jensen, L. H. Merrill and J. McGinnis, 1961. Influence of pelleting on metabolizable and productive energy of a complete diet for chicks. Poultry Sci. 40: 1446.
NEWS AND NOTES (Continued from page 1962) E. H. Miller, 1104 W. Gambier St., Mount Vernon, Ohio 43050 (Includes many of the original records of the A.P.A. Richard I. Miller, Extension Poultryman, University of Rhode Island, Kingston,
A
Rhode Island 02881 M. R. Nash, P.O. Box 102, Murphyboro, Illinois 62966 Everette Nelms, Montgomery, Louisiana 71454
(Continued on page 2009)
C C C
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for crumbles than for the same diets fed as mash. In addition, pelleting or crumbling may slightly increase the efficiency of utilization of metabolizable energy. In this respect Reddy et al. (1961) demonstrated an increase in the productive energy content of the diet due to pelleting. They attributed this to a reduction in energy used for prehension of food. Because chicks fed pellets were shown to spend considerably less time eating than those fed mash. Thus small increases in early liveweight gain due to crumbles can perhaps be expected even with high energy diets. If so, a further consideration relevant to the choice between crumbles and mash in starter diets would be whether or not differences in body weight at, say, 4 weeks of age, were maintained to market weight. The results of experiment 2, in which all groups were fed the same pelleted diet from 4 to 8 weeks of age, suggested that early differences in growth rate due both to dietary nutrient concentration and crumbles versus mash were no longer apparent at 8 weeks of age. If this were a real effect capable of repetition, then considerations of nutrient levels and method of preparing feed in starter diets might seem somewhat academic, if by market age differences of this magnitude had already disappeared. But this effect may have been due to chance. Because compensatory growth after a period of relative undernutrition would not be expected in the 4 to 8 week stage when incremental growth rate is normally still ac-
versus
POULTKY SCIENCE 51: 1968-1975,
INTRODUCTION EVERAL reports indicate that chicks consume more food and grow faster when fed pellets or crumbles than when the same diets are fed as mash. Part of the growth response may be due to chemical changes during the pelleting process (Allred et al., 1956). This might involve destruction of growth inhibitors and breakdown of food components during heat treatment, although Bolton (1960) showed that the chemical composition and digestibility of the diet was not affected by pelleting. In another case the increase in growth rate obtained was apparently entirely due
S
1972
to an increase in voluntary food intake with pelleted diets (Hamm and Stephenson, 1959). Thus the growth response to pellets or crumbles seems to be largely or in some cases entirely due to an increase in food consumption. Therefore an increase in energy and protein intake, which might be induced by raising the concentration of these nutrients in a mash diet, may reduce or eliminate the growth response from crumbling at higher dietary nutrient levels. Such an interaction between dietary nutrient concentration and method of preparing feed was demonstrated with turkey poults by Pepper et al. (1960). This paper reports
1968
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on May 24, 2015
ABSTRACT Two experiments were conducted to determine the effect of dietary nutrient concentration on the growth response to crumbles compared with mash in broiler starter diets. In the first experiment four diets with similar calorie: protein ratios and calculated energy levels of 2866, 2979, 3090 and 3205 kcal. M.E./kg. were fed ad libitum, as mash and as crumbles, to broiler chicks of mixed sex from 0 to 2 weeks of age. Biological determinations of metabolizable energy were done for the highest and lowest energy diets. These were in good agreement with calculated values. Determined values for crumbles were about one percent higher than corresponding values for mash. Differences between growth increments in favour of crumbles compared with mash were 35, 17, 11 and 9 percent as dietary nutrient concentration increased. With mash, growth rate increased by about 11, 4 and 2 percent for successive increases in dietary nutrient concentration. When the same diets were fed as crumbles no positive response was obtained and the lowest energy diet supported maximum growth. This experiment therefore demonstrated an interaction between dietary nutrient concentration and method of preparing feed. In the second experiment a third variable was introduced, body weight at day-old as influenced by age of dam when hatching eggs were laid, because it was considered that this would affect food intake and might influence the growth response to crumbles. In this experiment the highest and lowest energy diets were fed, as mash and as crumbles, to male chicks from 0 to 4 weeks of age. Half the chicks were obtained from younger dams and average body weight at day-old was 37g. The other half was obtained from older dams and their day-old weight was 44g. There were no significant interactions between dietary nutrient concentration, method of preparing feed and age of dam when hatching eggs were laid, for liveweight gain in the 0 to 4 week period. On average, chicks fed crumbles grew 9 and 6 percent faster than those fed mash, on the lower and higher energy diets respectively. Chicks ate more calories and grew faster on the higher compared with the lower energy diet. In the 0 to 4 week period chicks from older dams ate more food and grew significantly faster than chicks from younger dams. All groups were then fed the same pelleted grower diet from 4 to 8 weeks of age. Differences in early growth rate due to dietary nutrient concentration, crumbles versus mash and age of dam, were no longer apparent by 8 weeks of age.
ENERGY LEVELS AND CRUMBLES
two experiments designed to test this possibility with broiler chicks. In addition a third variable, body weight at day-old as influenced by age of dam when hatching eggs were laid, was introduced in the second experiment. Because it was considered that this would affect food intake and might influence the growth response to crumbles.
A total of 480 Ross broiler chicks were used in each experiment. These were of mixed sex in experiment 1 and males in experiment 2. In experiment 1 chicks were weighed at day-old and allocated at random to 32 groups of IS chicks in electrically heated battery brooders. Four groups were assigned at random to each of eight treatments. These consisted of 4 diets, each fed ad libitum as mash and as crumbles, from 0 to 2 weeks of age (1 January to 14 January, 1971). In experiment 2 the 480 day-old males, which were all hatched on the same day, consisted of 240 lighter chicks obtained from younger dams which were 31 weeks of age when hatching eggs were laid, and 240 heavier chicks from older dams of 54 weeks of age when eggs were laid. Within each of these categories, four groups of 15 chicks each were assigned at random to each of four feeding treatments in the same electrically heated battery brooders used in experiment 1. The feeding treatments consisted of two diets fed ad libitum as mash and as crumbles from 0 to 4 weeks of age (29 June to 27 July, 1971). At 4 weeks of age the four groups in each treatment were transferred and mixed in one of eight floor pens. All the birds in the experiment were then fed the same commercial pelleted diet from 4 to 8 weeks of age. This was to determine whether treatment differences in liveweight at day-old and at 4 weeks were maintained to market age.
MASH
1969
The experimental starter diets used in both experiments are shown in Table 1. The four diets were computer formulated by specifying energy levels calculated to increase in approximately equal steps from 2866 to 3205 kcal.M.E./kg. For each energy level appropriate minimum values were specified for 13 essential amino acids and calcium and phosphorus. Total protein was minimised to reduce unwanted surpluses of amino acids. Calorie:protein, calorie methionine and calorie:lysine ratios were calculated to be similar in each diet. However the calorie:protein ratios shown in Table 1 vary somewhat, because they were estimated using determined rather than calculated values for crude protein and in some cases for metabolizable enery. The diet fed to all groups in the 4 to 8 week period in experiment 2 was a proprietary compound estimated to support maximum growth at that stage. An amount of each of the four starter diets was mixed sufficient for experiment 1, but further mixing was necessary for the two starter diets used in experiment 2 (diets 1 and 4). Crude protein determinations were made on each mash mixture. In the case of the two diets 1 and 4, which were used in both experiments, crude protein determinations were in reasonable agreement for the two mixes and average values are therefore shown in Table 1. Determined crude protein values were 1 to 2 percentage points higher than calculated levels. Crumbles were made from pellets prepared using 6 mm. dies, after the mash had been exposed to a steam-heating process. As a check on the figures calculated using book values, biological determinations of metabolizable energy were done for diets 1 and 4 as mash and crumbles separately (see Table 1). Determinations were carried out by the total collection method over a 4 day period. This was not done on individuals. Instead, each diet was fed to a group of five 4 week old
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on May 24, 2015
MATERIALS AND METHODS
versus
1970
J. N. AUCKLAND AND R. B. FULTON TABLE 1.—Composition of starter diets 1
2
3
4
Maize Wheat Barley Soyabean meal Fish meal Groundnut oil Dried grassmeal DL-Methionine (98%) L-Lysine HC1 (97%) Limestone flour Dicalcium phosphate Salt Vitamins and trace minerals*
12.00 35.80 28.70 9.10 8.00 0.90 3.50 0.084 0.130 0.385 0.885 0.090 0.620
20.00 35.30 20.50 8.50 10.00 1.50 2.50 0.072 0.093 0.324 0.730 0.090 0.620
28.00 34.70 12.30 7.90 12.00 2.10 1.50 0.060 0.055 0.263 0.576 0.090 0.620
36.00 34.20 4.10 7.30 14.00 2.70 0.50 0.048 0.018 0.202 0.421 0.090 0.620
100
100
100
Calculated and determined analyses Mash Crumbles Calculated M.E., kcal./kg. Determined M.E., kcal./kg. 1 Calculated crude protein % Determined crude protein % 2 Calorie:protein ratio 3 Methionine % Methionine-(- cystine % Lysine % Calcium % Available phosphorus %
2866 2865 145
2979
146
Crumbles
Mash 3205
3090
2896 17.9 19.8 145 0.42 0.74 1.04 0.96 0.54
100
3300
3267 18.6 20.6 145 0.44 0.77 1.09 1.00 0.56
19.3 21.0 147 0.46 0.79 1.13 1.04 0.58
154
20.0 21.2 151 0.48 0.81 1.17 1.08 0.60
156
1 Each value was obtained using figures for total food intake and total droppings of 5 chicks over a 4 day period. 2 By kjeldahl analysis of mash diets. 3 Kcal. M.E./kg.^percent crude protein by kjeldahl. * Amounts furnished per kg. of diet—Vitamins: Vit. A 110001.U.; Vit. D 3 6001.U.; Vit. Ki 2.0 mg.; Ca pantothenate 9.8 mg.; niacin 9.8 mg., Choline CI 1326 mg.; Vit. Bi2 5.0 meg.; Folic acid 490 meg.; Vit. E 6 I.U. Trace minerals: copper sulphate 19 mg.; Iron sulphate 146 mg.; Zinc oxide 61 mg.; Manganese sulphate 69 mg.; Potassium iodide 1.3 mg.; Cobalt sulphate 2.4 mg.
chicks. Total food consumed and total droppings of each group were then used for the estimation of metabolizable energy. For diet 1 the determined value for mash was virtually identical to the figure calculated using book values, and the value for crumbles was about 1 percent higher. For diet 4, the determined value for mash was in reasonable agreement with the calculated value. And again the value for crumbles was about 1 percent higher than for mash. RESULTS
Experiment 1. Growth: Results of experiment 1 are shown in Table 2. Average body
weight at day-old was 41 g. per chick. Chicks fed crumbles grew faster than corresponding groups fed the mash diets. But differences in growth increments in favour of crumbles were greater at the lower than at the higher dietary nutrient levels—50, 27, 18 and IS g. per chick for diets 1, 2, 3 and 4 respectively. This interaction between dietary nutrient concentration and method of preparing feed approached significance at P = 0.05. With the mash diets growth rate increased by 11, 4 and 2 percent with successive increases in dietary nutrient concentration. This response suggests that the highest energy diet promoted near to the maximum growth rate possible
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Diet No.
ENERGY LEVELS AND CRUMBLES
with mash. When the same diets were fed as crumbles no positive response was obtained and the lowest energy diet was evidently adequate for maximum growth of these chicks.
versus
TABLE 2.—Results of Experiment 1 Treatment Code1
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0.192J
0.167
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0.1641
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4M
0.1671 (0.174 0.182)
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to. 173
1.71 (3.3
0.006 0.005 0.019 0.013
1
1, 2, 3, 4=diet numbers (see Table 1); M=mash, C = crumbles. 2 Liveweight less day-old weight.
tirely due to differences obtained for the lighter chicks. Since with heavier chicks from older dams the difference in growth rate in favour of crumbles was similar for each dietary energy level. The data for body weight at 8 weeks are also shown in Table 3. Least significant differences cannot be given since the 4 groups in each treatment were mixed together in one floorpen after 4 weeks of age. But the data strongly suggest that differences in early growth rate, in favour of chicks fed the higher energy starter diet, and in favour of crumbles rather than mash, were no longer apparent at 8 weeks of age. Similarly, early difference in favour of chicks from older dams had also disappeared by the 8 week stage. Unfortunately it could not be determined which treatment had the best overall feed efficiency, since food consumption in the 4 to 8 week period was not recorded. Food consumption: There were no significant treatment interactions for food consumption in the 0 to 4 week period (Table 4). On average, chicks fed the higher energy diet ate a similar amount of food and therefore considerably more calories and protein than groups fed the lower energy
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Experiment 2. Growth: Results of experiment 2 are shown in Tables 3 and 4. There were no significant interactions between dietary nutrient concentration, method of preparing feed and age of dam when hatching eggs were laid, for liveweight gain in the 0 to 4 week period (Table 3). On average, chicks fed the higher energy diet grew significantly faster than groups fed the lower energy diet. Chicks fed crumbles grew faster than those fed mash. Chicks from older dams were significantly heavier at one day of age and grew significantly faster than chicks from younger dams. Average growth increments were 0.577 and 0.S48 kg./bird for chicks from older and younger dams respectively. Although there were no significant interactions, there was a tendency for the growth response to crumbles to be smaller with the higher energy diet. Thus on average, chicks fed crumbles grew nearly 9 percent faster than those fed mash with the low energy diet. And with the higher energy diet, chicks fed crumbles grew nearly 6 percent faster than those fed mash (Table 3). And this tendency for the average growth response to crumbles to be less with the higher energy diet was en-
Liveweight gain2 0-2 weeks, kg./bird
IM
2M
Food consumption: Because of an error in recording food consumption in this experiment, the data for food consumption, nutrient intake and food conversion ratios are omitted. Mortality: There were no consistent differences in mortality due to dietary nutrient level but on the average mortality was greater for chicks fed crumbles than for those fed mash (Table 2).
1971
MASH
1972
J. N. AUCKLAND AND R. B. FULTON
Feed conversion ratios: The only significant interaction for feed conversion ratios in the 0 to 4 week period was between dietary nutrient concentration and age of dam (P = 0.05). This indicated that the faster-growing chicks from older dams had a similar or slightly more efficient feed conversion ratio on the lower energy diet but a somewhat poorer feed conversion ratio on the higher energy diet (Table 4). This was due to small and opposite differences in growth rate and feed consumption. Thus chicks from older dams ate about 5 percent more feed and grew about 7 percent faster than those from younger dams on the lower energy diet. But they ate about 9 percent more and grew only 4 percent faster on the higher energy diet (Tables 3 and 4). On average, feed conversion was significantly more efficient for chicks fed the higher compared with the lower energy diet (P = 0.001). Average feed conversion was marginally more efficient for chicks fed crumbles compared with those fed mash.
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diet. This indicated a marked inability to adjust food intake in response to changes in dietary nutrient concentration in this range. Chicks fed crumbles ate more food than those fed mash. Chicks from older dams ate more food than those from younger dams. Average food intake in the 0 to 4 week period was 38.5 and 36.0 g./bird day for chicks from older and younger dams respectively. These results for food consumption are consistent with the average growth responses obtained. Although there was no significant interaction, chicks fed crumbles ate on average about 7 percent more than those fed mash with the lower energy diet, whereas the corresponding increase was barely 5 percent with the higher energy diet (Table 4). This is consistent with the tendency for the growth response to crumbles to be somewhat smaller with the higher energy diet.
ENERGY LEVELS AND CRUMBLES
Mortality: On average, mortality was similar for chicks fed crumbles and those fed mash. Average mortality for chicks which were heavier at day-old and came from older dams was 3.3 percent, and for chicks from younger dams it was 3.9 percent. Mortality was lower for chicks fed the higher compared with the lower energy diet in this experiment (Table 3).
1973
MASH
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DISCUSSION Effect of age of dam when hatching eggs were laid. In spite of the lack of significant interactions in experiment 2, growth responses to crumbles and dietary nutrient concentration did tend to differ somewhat for the heavier and lighter chicks from older and younger dams. Increase in growth rate in the 0 to 4 week period, due to crumbles compared with mash, was similar for heavier and lighter chicks fed the lower energy diet. But with the higher energy diet it was 51 g. per chick for those from older dams and only 16 g. per chick for those from younger dams. For the heavier chicks the growth advantage in favour of crumbles was similar at each dietary energy level studied. Whereas for lighter chicks from younger dams the difference in favour of crumbles was 43 g. per chick on the lower energy diet and only 16 g. per chick on the higher energy diet. These tendencies for differences in response to dietary treatments, due to body weight at day-old, warrant further investigation. Differences in body weight at day-old due to age of dam when hatching eggs were laid, were still in evidence at 4 weeks but had apparently disappeared by 8 weeks of age. This is in general agreement with other investigations using both chicks and poults, which showed that the influence of egg size or body weight at hatching upon subsequent body weight was only apparent for a few weeks. Correlations between hatching weight and body weight at 8 or 12
versus
1974
J. N. AUCKLAND AND R. B. FULTON
weeks of age were insignificant and approached zero (Godfrey et al., 1953; Asmundson and Pun, 1954).
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Effect of dietary nutrient concentration on the response to crumbles. In both experiments chicks offered crumbles grew faster than when the same diets were fed as mash, In experiment 1 the growth response to crumbles decreased markedly and progressively as dietary nutrient concentration was increased. Chicks fed crumbles grew 35 and 9 percent faster than those fed mash, with the lowest and highest energy diets respectively. In experiment 2 dietary nutrient concentration had a less marked effect on the response to crumbles. On average, chicks fed crumbles grew about 9 and 6 percent faster than those fed mash, on the lower and higher energy diets. Giirocak (1971) found that growth of broilers in the 0 to 8 week period was 7.4 and 6.9 percent faster with pellets than with mash on low and higher energy diets respectively. This seems to support the smaller influence of dietary energy level on the growth response to crumbles obtained in the second experiment. However, the different age intervals considered (0-2 weeks experiment 1 and 04 weeks in experiment 2) and/or sex differences (mixed sex in experiment 1 and males in experiment 2) could conceivably have been responsible for this difference in magnitude of interaction in the two experiments. Growth responses to crumbles were of comparative magnitude for chicks fed the higher energy diet in the two experiments —nine percent in experiment 1 and six percent in experiment 2. It was at the lower dietary nutrient concentration where the response to crumbles was considerably greater in the first experiment. This difference between the two experiments cannot be adequately explained. It seems likely to be a reflection of differences in voluntary
food intake. The growth data for experiment 1 suggest that chicks were unable to adjust food intake, as nutrient concentration was lowered in the more bulky mash diets, with the result that chicks fed the lowest energy diet as mash probably ate an inadequate amount of calories and protein and therefore grew slowly. Whereas with crumbles voluntary food intake was apparently precisely adjusted so as to maintain a similar nutrient intake, as suggested by the similar growth rates obtained on the lowest and highest energy diets. Consequently there was a large growth advantage from feeding crumbles as opposed to mash with the lowest energy diet. In experiment 2 on the other hand, chicks fed crumbles were for some reason only slightly less inefficient than chicks fed mash at adjusting food intake in response to changes in dietary nutrient concentration. Thus with mash there was zero adjustment in the sense that voluntary food intake was identical for the lower and higher energy diets. With crumbles, food consumption was only about 2 percent greater and calorie intake consequently about 8 percent less, on the lower energy diet (see Table 4). However, in both experiments the growth response to crumbles did decrease as dietary nutrient concentration increased. In both cases there was still a growth advantage of 6 to 9 percent in favour of crumbles even with the highest energy diet fed. Although it is possible that a dietary energy concentration greater than 3.3 kcal. M.E./g. might have further reduced or even eliminated the growth responses to crumbles which were obtained. On the other hand it seems likely that a small amount of extra growth, probably mainly as extra body fat, may be obtained from crumbles as opposed to mash even at higher dietary energy levels and calorie intakes. Because determined metabolizable energy values were about 1 percent higher
ENERGY LEVELS AND CRUMBLES
MASH
1975
celerating. Since by definition this means that growth rate at any point in this phase tends to be proportional to growth already made or body weight to which it is being added (Brody, 1926). Thus a nutrition induced weight advantage at 4 weeks of age should theoretically be increased, or at least maintained at the same absolute level, to 8 weeks of age. REFERENCES Allred, J. B., L. S. Jensen and J. McGinnis, 1956. Studies on the growth promoting effect induced by pelleting feed. Poultry Sci. 35: 1130. Asmundson, V. S., and C. F. Pun, 1954. Growth of Bronze turkeys. Poultry Sci. 33 : 981-986. Bolton, W., 1960. The digestibility of mash and pellets by chicks. J. Agric. Sci. 55: 141-142. Brody, S., 1926. Growth and development with special reference to domestic animals, iii. Growth rates, their evaluation and significance. Missouri Agric. Exp. Sta. Bull. No. 97. Godfrey, G. F., C. Williams and C. E. Marshall, 1953. The relative influence of egg size, age at sexual maturity and mature body weight on growth to 12 weeks of age. Poultry Sci. 32 : 496-500. Giirocak, L., 1971. Investigations concerning the influence of pelleting broiler rations on the performance. World Poultry Sci. J. 27: 174-175. Hamm, D., and E. L. Stephenson, 1959. The pelleting response in broiler feeding. Poultry Sci. 38: 1211. Pepper, W. F., S. J. Slinger and J. D. Summers, 1960. Studies with chickens and turkeys on the relationship between fat, unidentified factors and pelleting. Poultry Sci. 39: 66-74. Reddy, C. V., L. S. Jensen, L. H. Merrill and J. McGinnis, 1961. Influence of pelleting on metabolizable and productive energy of a complete diet for chicks. Poultry Sci. 40: 1446.
NEWS AND NOTES (Continued from page 1962) E. H. Miller, 1104 W. Gambier St., Mount Vernon, Ohio 43050 (Includes many of the original records of the A.P.A. Richard I. Miller, Extension Poultryman, University of Rhode Island, Kingston,
A
Rhode Island 02881 M. R. Nash, P.O. Box 102, Murphyboro, Illinois 62966 Everette Nelms, Montgomery, Louisiana 71454
(Continued on page 2009)
C C C
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for crumbles than for the same diets fed as mash. In addition, pelleting or crumbling may slightly increase the efficiency of utilization of metabolizable energy. In this respect Reddy et al. (1961) demonstrated an increase in the productive energy content of the diet due to pelleting. They attributed this to a reduction in energy used for prehension of food. Because chicks fed pellets were shown to spend considerably less time eating than those fed mash. Thus small increases in early liveweight gain due to crumbles can perhaps be expected even with high energy diets. If so, a further consideration relevant to the choice between crumbles and mash in starter diets would be whether or not differences in body weight at, say, 4 weeks of age, were maintained to market weight. The results of experiment 2, in which all groups were fed the same pelleted diet from 4 to 8 weeks of age, suggested that early differences in growth rate due both to dietary nutrient concentration and crumbles versus mash were no longer apparent at 8 weeks of age. If this were a real effect capable of repetition, then considerations of nutrient levels and method of preparing feed in starter diets might seem somewhat academic, if by market age differences of this magnitude had already disappeared. But this effect may have been due to chance. Because compensatory growth after a period of relative undernutrition would not be expected in the 4 to 8 week stage when incremental growth rate is normally still ac-
versus