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The Effects of Different Protein and Energy Levels and Time of Change from Starter to Finisher Ration on the Performance of Broiler Chickens in the Tropics
The Effects of Different Protein and Energy Levels and Time of Change from Starter to Finisher Ration on the Performance of Broiler Chickens in the Tropics J. M. OLOMU and S. A. OFFIONG Department of Animal Husbandry and Biochemistry, National Animal Production Research Institute, Ahmadu Bello University, Shika, Zaria, Nigeria (Received for publication December 11, 1978)
1980 Poultry Science 59:828-835 INTRODUCTION One of t h e major setbacks of t h e broiler industry in Nigeria is t h e limited k n o w l e d g e of t h e n u t r i t i o n a l r e q u i r e m e n t s of p o u l t r y raised t h e r e . A t t e m p t s t o use feed formulas based o n protein and energy levels found suitable for t h e t e m p e r a t e zones have n o t been t o o successful. Very little w o r k has been d o n e o n t h e effects of p r o t e i n and energy levels o n t h e performance of broiler chickens raised in t h e tropics. B a b a t u n d e a n d Fetuga ( 1 9 7 6 ) recomm e n d e d crude p r o t e i n levels n o t less t h a n 2 4 and 18%, respectively, for broiler starters and finishers. These workers did n o t r e p o r t t h e effects of energy levels o n t h e p e r f o r m a n c e of t h e birds. Olomu ( 1 9 7 6 ) r e c o m m e n d e d a protein level of 2 3 % and m e t a b o l i z a b l e energy
(ME) of b e t w e e n 2 8 0 0 and 3 0 0 0 kcal/kg diet for broiler starters. N o information was given for broiler finishers. Both B a b a t u n d e and Fetuga ( 1 9 7 6 ) and O l o m u ( 1 9 7 6 ) based their r e c o m m e n d a t i o n s o n work d o n e in t h e s o u t h e r n , h u m i d parts of Nigeria. F u r t h e r research w o r k was t h u s t h o u g h t necessary in order t o o b t a i n values t h a t would b e widely applicable to t h e whole c o u n t r y . T h e limited information available o n t h e energy r e q u i r e m e n t s of broiler chickens and o n t h e o p t i m u m t i m e of change from broiler starter t o broiler finisher rations also necessitated further research w o r k . T h e present studies were u n d e r t a k e n t o determ i n e t h e o p t i m u m p r o t e i n and energy levels for broiler starters and finishers raised in t h e tropics as typified by t h e n o r t h e r n , drier part of 828
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ABSTRACT Three experiments were conducted to determine the optimum protein and energy levels for starting and finishing broiler chickens and the optimum time of change from broiler starter rations to broiler chicken finisher rations. We tested four protein levels (17, 20, 23, and 26%), each fed at three energy levels (2800, 3000, and 3200 kcal/kg diet). For starting chickens, maximum weight gains, feed efficiency, and lowest feed cost per kilogram live weight gain were obtained on the rations containing 23 or 26% protein. Differences in dietary energy levels did not significantly affect weight gain and feed consumption. Feed efficiency improved with increase in dietary energy levels although the differences in feed efficiency between any two consecutive groups were not significant. Feed cost tended to increase nonsignificantly with increase in energy level. For finishing broiler chickens, dietary protein level did not have any significant effects on weight gains. The poorest weight gain, feed efficiency, and feed cost per kilogram gain were obtained on the rations containing 17% protein. The differences in feed efficiency between protein levels of 20, 23, and 26% were not significant while no two consecutive protein levels among the 20, 23, and 26% protein diets gave feed cost per kilogram gain that was significantly different from each other. Weight gain, feed consumption, and feed cost per kilogram gain were not significantly affected by dietary energy levels. Efficiency of feed conversion tended to improve with increase in dietary energy levels, although differences in feed efficiency between 3000 and 3200 kcal/kg diet were not significant. Performances of birds fed the starter ration for 0, 1, 2, 3, or 4 weeks before changing to the finisher ration were not as good as those fed the starter ration for 5 or 6 weeks before being changed to the finisher ration or those fed the starter ration for the 9 weeks experimental period. The results of the present work indicate that a protein level of 23% and energy level of 2800 to 3000 kcal/kg diet may be recommended for starting broiler chicks raised in Nigeria. For finishing broiler chickens, a protein level of 20% and energy level of 3000 kcal/kg diet may be recommended. The optimum time of change from broiler starter to broiler finisher may be recommended at 5 or 6 weeks of age.
PROTEIN AND ENERGY FOR BROILER CHICKENS Nigeria. In addition, the optimum time of change from broiler starter to broiler finisher was also determined.
EXPERIMENTAL PROCEDURE
Experiment
3.
In
the
experiment,
the
optimum time of change from broiler starter ration to broiler finisher ration was determined. The composition of the rations used together with the prices of the ingredients are shown in Table 2. The chicks were placed on the experimental treatments from day-old and the experiment was terminated when the birds were 9 weeks old. Details of the time of change from broiler starter ration to broiler finisher ration are outlined in Table 6. In all experiments the chickens were weighed in groups at weekly intervals and feed consumption was recorded. A record of mortality was kept. RESULTS Experiment 1. Results of Experiment 1 are presented in Table 3. Weight gain, feed efficiency, and feed cost per kilogram of gain improved as the protein level was increased stepwise from 17 to 23%. Analysis of variance of these data (Table 4) showed the differences to be significant at the one percent level, and the trend with increase in protein level being quadratic in nature. Weight gain and feed cost per kilogram of gain at the 23 and 26% protein levels did not differ significantly from each other but were significantly better than those obtained on the lower protein levels. Feed efficiency improved significantly with increase in protein levels up to 23% and deteriorated significantly at 26% protein. Feed consumption was not significantly affected by protein levels. Dietary energy levels did not exert any significant effects on weight gain, feed consumption and feed cost per kilogram gain. The significant effect of energy levels on feed efficiency was linear in nature at the one percent level. The feed efficiency at the highest energy level (3200 kcal/kg diet) was significantly better than that at the lowest energy level (2800 kcal/kg diet) but not significantly better than that at the medium energy level (3000 kcal/kg diet). There was no significant interaction between the protein and energy levels in all the parameters studied. Apart from the ration containing 17% protein, other rations gave performance better than the commercial ration. Mortality on all the treatments was generally low (less than 2%) and not significantly affected by dietary protein or energy levels. Experiment 2. The results of this experiment are summarized in Table 5. Analysis of variance
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Three experiments were conducted using Ross broiler-type chicks of mixed sexes. The chicks were randomly distributed into groups of fifty and assigned to floor pens (3.05 X 1.22 m/pen) which were heated during the first four weeks of the birds' lives. Each experimental diet was fed to two pens of 50 chicks per pen in each experiment. Thus, two replicates of 50 birds per replicate were assigned to each experimental ration. Feed and water were supplied ad libitum. Continuous lighting was provided. Daily ambient temperatures were measured and relative humidity determined by means of a wet and dry bulb thermometer. Experiments I and 2. These experiments were conducted to determine the optimum protein and energy levels for starting and finishing broiler chickens, respectively. In these experiments, four protein levels (17, 20, 23, and 26%) and three metabolizable energy levels (2800, 3000, and 3200 kcal/kg diet) were tested. The metabolizable energy levels were calculated using the individual metabolizable energy values of the ingredients as outlined by NRC (1971). The composition of the experimental rations used and prices of individual ingredients are shown on Table 1. A thirteenth ration consisted of a commercial broiler ration containing 23% protein (Experiment 1) or a broiler finisher ration containing 20% protein (Experiment 2). In Experiment 1, day-old chicks averaging 45 g per chick were used and the experiment was terminated when the birds were five weeks old. In Experiment 2, the birds were fed the ration found optimum from Experiment 1 for 6 weeks before they were used to determine the requirements for energy and protein. The birds weighed approximately 1060 g per chicken when they were placed on the experimental treatments. The experiment was terminated when the birds were nine weeks old. At the end of Experiment 2, 10 chickens per replicate were randomly selected and slaughtered for carcass evaluation. All data collected during the experiments were subjected to analysis of variance and significance of differences assessed at 5% level of significance (Steel and Torrie, 1960).
829
.83
.83
.328
.83
.334
.323
1.22
1.22
1.22 .317
.83
1.22
.82
.75
.95 .69
26.1 2800 1.16
23.1 2800 1.06
.84 .62
20.1 2800
.30 .50
.1Q .50
.30 .50
.30 .50
.05
2.00 1.00
.05
2.00 1.00
44.45 39.20 5.00 7.50
.05
4
2.00 1.00
50.00 29.65 9.00 7.50
55.55 20.10 13.00 7.50
3
.05
2
2.00 1.00
61.10 10.55 17.00 7.50
17.1 2800
1
.30 .50
59.45 11.80 14.50 7.50 2.95 2.00 1.00
.352
.83
1.22
.84 .62
17.1 3000
5
.30 .50
.348
.83
1.23
.95 .68
.30 .50
48.35 30.90 6.50 7.50 2.95 2.00 1.00
.342
.83
1.23
.75
23.1 3000 1.05
(%)
7
Rations
53.90 21.35 10.50 7.50 2.95 2.00 1.00
20.1 3000
6
26.
. .
42. 40. 2. 7. 2. 2. 1.
. .
. 1.
1.
3000
8
Costs are based on prices of ingredients during period of experiment.
Supplied per kilogram ration: vitamin A, 10,000 IU; vitamin D 3 2000 ICU; vitamin E, 5 IU; vitamin K, 2.24 panthothenate, 10 mg; niacin, 25 mg; choline chloride, 350 mg; folic acid, 1 mg; manganese, 56 mg; zinc, 50 mg; co 125 mg; terramycin, 100 mg.
Yellow corn Groundnut cake Wheat bran Fish meal Palm oil Bone meal Periwinkle shell Common salt Premix a Calculated analysis: Crude protein (%) ME (kcal/kg diet) Lysine (%) Methionine (%) Calcium (%) Phosphorus (%) Cost," $/kg ration
Ingredients
TABLE 1. Composition of rations used in Experiments 1 and 2
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831
PROTEIN AND ENERGY FOR BROILER CHICKENS TABLE 2. Prices of ingredients and composition of rations ued in Experiment 3 Ingredients price/metric ton Experiment 1 and 2
Ingredients
d
Experiment 3
467 203 117
343 187 109 935 866 156 156 347 1948
Composition of rations (Experiment 3)
48.35 30.90 6.50 7.50 2.95 2.00 1.00
1091 1351 L56 156 519
Finisher ration
Starter ration - (%)
53.85 24.70 9.45 5.00 2.95 2.25 1.00 .30 .50
.30 .50
1948
23.1 3000 1.05
20.1 3000
.75
.82 .65
1.23
1.23
.83
.83
.435
.424
See Table 1.
of these data (Table 6) showed that the dietary protein levels did not significantly affect weight gain and feed consumption. The significant effects of protein levels on feed efficiency were linear at the 1% level. The differences between protein levels of 17, 20, and 23% were not
significant, nor were the differences significant in feed efficiency between protein levels of 20, 23, and 26%. The differences in feed cost per kilogram gain were significant, the trend being linear at the 1% level. The differences in feed cost per kilogram gain between protein levels of
TABLE 3. Effects of varying protein and energy levels on performance of starting broiler chicks (0 to 5 weeks, Experiment l)a
Ration no.
Protein level
Energy level (kcal/kg diet)
2800 2800 2800 2800 3000 3000 3000 3000 3200 3200 3200 3200 13 Commercial broiler starter 1 2 3 4 5 6 7 8 9 10 11 12
17 20 23 26 17 20 23 26 17 20 23 26
Average weight gain (g)
Feed consumption (g feed/bird)
EFC
(g/feed g gain)
Feed cost/kg live weight gain ($)
654 789 838 838 661 800 854 839 667 800 841 798 785
1617 1688 1668 1755 1645 1668 1662 1622 1649 1668 1635 1514 1730
2.48 2.14 1.99 2.10 2.48 2.08 1.94 1.94 2.38 2.08 1.94 1.90 2.10
.83 .70 .64 .66 .87 .73 .67 .66 .89 .76 .70 .67 .92
a Average maximum temperature 30.6 C; average minimum temperature, 14.0 C; average relative humidity, 11.5%
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Yellow corn Groundnut cake Wheat bran Fish meal Palm oil Bone meal Periwinckle shell Common salt Premixa Calculated analysis: Crude protein (%) ME (kcal/kg diet) Lysine (%) Methionine (%) Calcium (%) Phosphorus (%) Cost, $/kg ration
($)
OLOMU AND OFFIONG
832
TABLE 4. Analysis of variance for data obtained from Experiment 1 Mean squares df
Weight gain
Treatments (T) Protein level (P) P linear P quadratic P cubic Energy level (E) E linear E quadratic PX E
11 3 1 1 1 2 1 1 6
11514.70** 41282.94** 87511.86** 36201.21** 135.74 297.51 38.72 556.31 369.64
6777.62 3889.80 100.06 10023.78 1545.57 13052.98 25821.08 283.87 6129.73
EFC
Feed cost/ kg gain
.096** .306** .781** .132** .006 .045* .083** .007 .007
.015** .052** .137** .017** .001 .003 .004 .001 .001
*(P<.05). **(P<.01).
20, 23, and 26% were not significant while the lowest protein level (17%) significantly increased feed cost per kilogram gain. Dietary energy levels did not signifcantly affect weight gain, feed consumption, and feed cost per kilogram gain. Feed consumption, however, tended to decrease with increase in dietary energy level. The significant effects exerted by dietary energy levels on feed efficiency were linear at the 1% level. Feed efficiency improved significantly when the energy was increased from 2800 to 3000 kcal/kg diet. The improvement obtained when the energy was further increased from 3000 to
3200 kcal/kg diet was not significant. There were no significant interactions between the protein and energy levels in all the parameters studied. The effects of dietary treatments on mortality were minimal (less than 1%) and did not follow any particular trend. The commercial ration gave the lowest weight gain, poorest feed efficiency, and highest feed cost per kilogram of gain. Dietary treatments did not exert any significant effects on the percentages of carcass plus neck, gizzard, liver, and heart (Table 7). Experiment 3. Summarized in Table 8 are
TABLE 5. Effects of varying protein and energy levels on performance of finishing broiler chickens (6 to 9 weeks, Experiment 2)a
Ration no.
Protein level
Energy level (kcal/kg diet)
2800 2800 2800 2800 3000 3000 3000 3000 3200 3200 3200 3200 13 Commercial broiler finisher
1 2 3 4 5 6 7 8 9 10 11 12
17 20 23 26 17 20 23 26 17 20 23 26
Average weight gain (g)
Feed consumption (g feed/bi rd)
EFC
792 845 878 902 846 939 938 962 824 932 932 890 708
2484 2550 2593 2466 2382 2508 2549 2456 2239 2409 2368 2364 2268
3.13 3.04 2.96 2.78 2.82 2.68 2.72 2.56 2.72 2.58 2.55 2.66 3.20
(g feed/g gain)
Feed cost/kg live weight gain ($)
1.01 .97 .92 .86 .97 .90 .89 .83 .98 .92 .89 .92
1.31
Average maximum temperature, 32.3 C; average minimum temperature, 18.9 C; relative humidity, 13.75%.
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Source
Feed consumption
83 3
PROTEIN AND ENERGY FOR BROILER CHICKENS TABLE 6. Analysis of variance for data obtained from Experiment 2. Mean squares df
Weight gain
Treatment (T) Protein level (P) P linear P quadratic P cubic Energy level (E) E. linear E quadratic PX E
11 3 1 1 1 2 1 1 6
4905.19 5321.82 11662.41 4030.04 273.01 11419.62 16965.06 5874.19 2525.40
11923.97 4605.02 404.54 12312.99 1097.53 28718.04 57435.72 .359 9985.43
EFC
Feed cost/ kg gain
.073** .053* .149** .004 .007 .282** .497** .068 .013
.006* .015** .043** .001 .001 .004 .001 .006 .002
*(P«.05). **(P«.01).
the results of Experiment 3. As compared to the group fed the starter ration up to market weight, weight gains of the birds were only significantly depressed when the birds were changed from starter to finisher ration at less than three weeks of age. Comparable weight gains with the control ration (Treatment 1) were obtained when the birds were fed starter ration for 5 or 6 weeks (Treatment 7 or 8) before being changed to the finisher ration. Weight gains obtained on Treatments 1, 7, and 8 were significantly better than those on Treatment 2 (finisher ration). Feed consump-
tion, feed efficiency, and feed cost per kilogram of gain were not significantly affected by dietary treatment. DISCUSSION The trend of improving weight gains and feed efficiency with increasing dietary protein up to 23% for starting broiler chicks is in agreement with previous findings in the tropics (Olomu, 1976). Similar improvement in weights and feed efficiency as the dietary protein level increased from 14% to 24% had also been
TABLE 7. Effects of varying protein and energy levels on carcass dressing percentages of broiler chickens (Experiment 2)a
Ration
Protein level
no.
(%)
Energy level (kcal/kg diet)
Carcass + neck
Gizzard
1 2 3 4 5 6 7 8 9 10 11 12
17 20 23 26 17 20 23 26 17 20 23 26
2800 2800 2800 2800 3000 3000 3000 3000 3200 3200 3200 3200
71.52 67.02 69.62 68.41 68.88 70.15 70.44 68.90 69.71 68.10 68.52 69.58 67.17
2.48 2.27 2.16 2.18 2.44 2.27 1.98 2.00 2.07 2.16 2.18 2.16 2.26
13 Commercial broiler finisher l
All column values were not significantly different .(P<.05).
(">)
Liver
Heart
2.05 2.10 1.93 2.10 2.17 2.07 1.72 1.80 1.92 2.00 1.88 2.06 2.40
.676 .606 .654 .642 .716 .672 .584 .616 .618 .628 .619 .616 .654
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Source
Feed consumption
834
OLOMU AND OFFIONG TABLE 8. Effects of time of change from broiler chicken starter ration to broiler chicken finisher ration (Experiment 3)1
Treatment no.
Finisher3 ration (weeks)
Average weight gain (g)
Feed consumption (g/bird)
EFC (g feed/g gain)
Feed cost/kg live weight gain ($)
0-9 1 -9 2-9 3 -9 4-9 5- 9 6-9
1928 a 1739 c 1768bc 1743 c 1856abc 1849abc 1928 a 1919 a
4693 4497 4510 4486 4681 4660 4791 4769
2.43 2.58 2.56 2.58 2.52 2.52 2.49 2.44
1.06 1.09 1.09 1.09 1.08 1.06 1.06 1.06
0-9 0 - 1 0-2 0-3 0-4 0-5 0-6 a
' ' c Column values with same superscript are not significantly different (P<.05).
1
Average maximum temperature, 28.8 C: average minimum temperature, 19.7 C; average relative humidity, 17%. 2 Period for which chicken broiler starter ration was fed. 3 Period for which chicken broiler finisher ration was fed.
reported by Babatunde and Fetuga (1976). The level of protein (23%) found optimum in this. study may thus be considered optimum for starting broiler chicks in Nigeria and is in agreement with the recommendation for some temperate countries (NRC, 1971). The results obtained in the present studies also agree with previous findings (Farrell et al., 1973; Olomu, 1976) that there is an optimum energy concentration in a ration beyond which performance of chicks does not appear to improve and, in some cases, actually deteriorates. In the present study with starting chicks, no statistically significant improvement in weight gain, feed consumption, and feed cost per kilogram gain were recorded for diets containing over 2800 kcal/kg diet. There was, however, a significant improvement in feed efficiency when the energy level was increased from 2800 to 3000 kcal/kg diet and no further significant improvement when the energy was increased from 3000 to 3200 kcal/kg diet. The optimum energy level for broiler chicks in the drier Guinea Savanna zone of Nigeria may thus be set at 2800 to 3000 kcal/kg diet in agreement with levels recommended for the more humid forest areas of Nigeria (Olomu, 1976). The recommended energy level is lower than that (3200 kcal/kg diet) recommended for some temperate countries by NRC (1971) and that (3100 kcal/kg diet) assumed by ARC (1975) as optimum. It is possible that broiler chicks perform better at lower dietary energy levels in the tropics
because of the higher environmental temperature which probably calls for lower energy needs to maintain basal metabolism. This may be true irrespective of whether the birds are raised in the humid forest zones of Nigeria (Olomu, 1976) or in the drier Guinea Savanna zones of Nigeria (present studies). The study with finishing broiler chickens indicates an obvious advantage of the ration containing 3000 kcal/kg diet over other rations in terms of at least weight gain and feed cost per kilogram of liveweight gain. No further improvement in feed efficiency was obtained when the energy level was increased from 3000 to 3200 kcal/kg diet. Protein levels above 20% did not exert any additional advantage. No published information with finishing broiler chickens in Nigeria is available at present to compare with the present results. The recommended protein level, however, agrees with that recommended for some temperate countries, but the energy level is lower than that recommended (3200 kcal/kg) for some temperate countries (NRC, 1971). The present results with finishing broiler chickens also indicate that within the range of protein and energy tested, it is difficult to alter the dressing percentages of the carcass plus neck and the giblets by dietary alteration of protein and energy. The results of the third experiment indicate that broiler chickens should not be changed
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1 2 3 4 5 6 7 8
Starter 2 ration (weeks)
PROTEIN AND ENERGY FOR BROILER CHICKENS
concentrates that will give a final energy level that is consistent with optimum broiler production in Nigeria and that is lower than that found optimum in temperate zones. ACKNOWLEDGMENTS
The authors wish to thank Saka Nuru, Director, National Animal Production Research Institute for permission to publish this paper. The assistance of S. A. S. Olorunju in statistical analysis is acknowledged. REFERENCES Agricultural Research Council, 1975. The nutrient requirements of farm livestock. No. 1, Poultry. 2nd ed. (rev.) ARC, London. Babatunde, G. M., and B. L. Fetuga, 1976. Determination of the minimum crude protein requirements of broiler starters and finishers in the tropics. Nigerian J. Anim. Prod. 3:126—138. Farrell, D. J., R. B. Cumming, and J. B. Hardaker, 1973. The effects of dietary energy concentration on growth rate and conversion of energy to weight gain in broiler chickens. Brit. Poultry Sci. 14:329-340. National Research Council, 1971. Nutrient requirements of poultry. 6th ed. Nat. Acad. Sci., Washington, DC. Olomu, J. M., 1976. Determination of optimum protein and energy levels for broiler chicks in the tropics. Nigerian J. Anim. Prod. 3:177-183. Olomu, J. M., A. R. Robblee, and D. R. Clandinin, 1974. Effects of processing and amino acid supplementation on the nutritive value of rapeseed for broilers. Poultry Sci. 53:175-184. Olomu, J. M., A. R. Robblee, and D. R. Clandinin, 1975. Utilization of full fat rapeseed and rapeseed meals in ration for broiler chicks. Can. J. Anim. Sci. 55:461-469. Steel, R. G. D., and Torrie, J. H., 1960. Principles and procedures of statistics. McGraw-Hill Book Company, Inc., New York.
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from broiler starter rations to broiler finisher rations earlier than 3 weeks of age. The best time to change seemed to be 5 or 6 weeks of age. No data are available at the moment in Nigeria to compare with the present results, although the time of change agrees with that recommended for some temperate countries by NRC (1971). It is also interesting to note that the broiler starter ration could be fed for the whole period without any added cost in terms of feed cost per kilogram of diet. At the recommended protein and energy levels, the performance of chickens fed the broiler starter was as good as that of chickens fed broiler starters reared in North America on a similar protein but a higher energy level by Olomu et al. (1974, 1975). At 9 weeks of age, weights and feed conversion obtained were also similar to those outlined for temperate zones by NRC (1971). The implications of the present and previous studies become pertinent in view of the lack of feed standards in Nigeria. A committee set up by the Nigerian Federal Government is already working on drawing up feed standards for the country but is being limited in its work by the lack of adequate data on optimum levels of nutrients for farm animals. Since the present and previous studies were carried out in two different areas of the country, representing two different ecological zones, the data obtained may be used to set up preliminary feed standards for broiler chickens, at least with respect to protein and energy. The results may also prove useful to foreign feed enterpreneurs who export their concentrates to Nigeria. It may be necessary in the future that such enterpreneures formulate
835
1980 Poultry Science 59:828-835 INTRODUCTION One of t h e major setbacks of t h e broiler industry in Nigeria is t h e limited k n o w l e d g e of t h e n u t r i t i o n a l r e q u i r e m e n t s of p o u l t r y raised t h e r e . A t t e m p t s t o use feed formulas based o n protein and energy levels found suitable for t h e t e m p e r a t e zones have n o t been t o o successful. Very little w o r k has been d o n e o n t h e effects of p r o t e i n and energy levels o n t h e performance of broiler chickens raised in t h e tropics. B a b a t u n d e a n d Fetuga ( 1 9 7 6 ) recomm e n d e d crude p r o t e i n levels n o t less t h a n 2 4 and 18%, respectively, for broiler starters and finishers. These workers did n o t r e p o r t t h e effects of energy levels o n t h e p e r f o r m a n c e of t h e birds. Olomu ( 1 9 7 6 ) r e c o m m e n d e d a protein level of 2 3 % and m e t a b o l i z a b l e energy
(ME) of b e t w e e n 2 8 0 0 and 3 0 0 0 kcal/kg diet for broiler starters. N o information was given for broiler finishers. Both B a b a t u n d e and Fetuga ( 1 9 7 6 ) and O l o m u ( 1 9 7 6 ) based their r e c o m m e n d a t i o n s o n work d o n e in t h e s o u t h e r n , h u m i d parts of Nigeria. F u r t h e r research w o r k was t h u s t h o u g h t necessary in order t o o b t a i n values t h a t would b e widely applicable to t h e whole c o u n t r y . T h e limited information available o n t h e energy r e q u i r e m e n t s of broiler chickens and o n t h e o p t i m u m t i m e of change from broiler starter t o broiler finisher rations also necessitated further research w o r k . T h e present studies were u n d e r t a k e n t o determ i n e t h e o p t i m u m p r o t e i n and energy levels for broiler starters and finishers raised in t h e tropics as typified by t h e n o r t h e r n , drier part of 828
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ABSTRACT Three experiments were conducted to determine the optimum protein and energy levels for starting and finishing broiler chickens and the optimum time of change from broiler starter rations to broiler chicken finisher rations. We tested four protein levels (17, 20, 23, and 26%), each fed at three energy levels (2800, 3000, and 3200 kcal/kg diet). For starting chickens, maximum weight gains, feed efficiency, and lowest feed cost per kilogram live weight gain were obtained on the rations containing 23 or 26% protein. Differences in dietary energy levels did not significantly affect weight gain and feed consumption. Feed efficiency improved with increase in dietary energy levels although the differences in feed efficiency between any two consecutive groups were not significant. Feed cost tended to increase nonsignificantly with increase in energy level. For finishing broiler chickens, dietary protein level did not have any significant effects on weight gains. The poorest weight gain, feed efficiency, and feed cost per kilogram gain were obtained on the rations containing 17% protein. The differences in feed efficiency between protein levels of 20, 23, and 26% were not significant while no two consecutive protein levels among the 20, 23, and 26% protein diets gave feed cost per kilogram gain that was significantly different from each other. Weight gain, feed consumption, and feed cost per kilogram gain were not significantly affected by dietary energy levels. Efficiency of feed conversion tended to improve with increase in dietary energy levels, although differences in feed efficiency between 3000 and 3200 kcal/kg diet were not significant. Performances of birds fed the starter ration for 0, 1, 2, 3, or 4 weeks before changing to the finisher ration were not as good as those fed the starter ration for 5 or 6 weeks before being changed to the finisher ration or those fed the starter ration for the 9 weeks experimental period. The results of the present work indicate that a protein level of 23% and energy level of 2800 to 3000 kcal/kg diet may be recommended for starting broiler chicks raised in Nigeria. For finishing broiler chickens, a protein level of 20% and energy level of 3000 kcal/kg diet may be recommended. The optimum time of change from broiler starter to broiler finisher may be recommended at 5 or 6 weeks of age.
PROTEIN AND ENERGY FOR BROILER CHICKENS Nigeria. In addition, the optimum time of change from broiler starter to broiler finisher was also determined.
EXPERIMENTAL PROCEDURE
Experiment
3.
In
the
experiment,
the
optimum time of change from broiler starter ration to broiler finisher ration was determined. The composition of the rations used together with the prices of the ingredients are shown in Table 2. The chicks were placed on the experimental treatments from day-old and the experiment was terminated when the birds were 9 weeks old. Details of the time of change from broiler starter ration to broiler finisher ration are outlined in Table 6. In all experiments the chickens were weighed in groups at weekly intervals and feed consumption was recorded. A record of mortality was kept. RESULTS Experiment 1. Results of Experiment 1 are presented in Table 3. Weight gain, feed efficiency, and feed cost per kilogram of gain improved as the protein level was increased stepwise from 17 to 23%. Analysis of variance of these data (Table 4) showed the differences to be significant at the one percent level, and the trend with increase in protein level being quadratic in nature. Weight gain and feed cost per kilogram of gain at the 23 and 26% protein levels did not differ significantly from each other but were significantly better than those obtained on the lower protein levels. Feed efficiency improved significantly with increase in protein levels up to 23% and deteriorated significantly at 26% protein. Feed consumption was not significantly affected by protein levels. Dietary energy levels did not exert any significant effects on weight gain, feed consumption and feed cost per kilogram gain. The significant effect of energy levels on feed efficiency was linear in nature at the one percent level. The feed efficiency at the highest energy level (3200 kcal/kg diet) was significantly better than that at the lowest energy level (2800 kcal/kg diet) but not significantly better than that at the medium energy level (3000 kcal/kg diet). There was no significant interaction between the protein and energy levels in all the parameters studied. Apart from the ration containing 17% protein, other rations gave performance better than the commercial ration. Mortality on all the treatments was generally low (less than 2%) and not significantly affected by dietary protein or energy levels. Experiment 2. The results of this experiment are summarized in Table 5. Analysis of variance
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on February 26, 2015
Three experiments were conducted using Ross broiler-type chicks of mixed sexes. The chicks were randomly distributed into groups of fifty and assigned to floor pens (3.05 X 1.22 m/pen) which were heated during the first four weeks of the birds' lives. Each experimental diet was fed to two pens of 50 chicks per pen in each experiment. Thus, two replicates of 50 birds per replicate were assigned to each experimental ration. Feed and water were supplied ad libitum. Continuous lighting was provided. Daily ambient temperatures were measured and relative humidity determined by means of a wet and dry bulb thermometer. Experiments I and 2. These experiments were conducted to determine the optimum protein and energy levels for starting and finishing broiler chickens, respectively. In these experiments, four protein levels (17, 20, 23, and 26%) and three metabolizable energy levels (2800, 3000, and 3200 kcal/kg diet) were tested. The metabolizable energy levels were calculated using the individual metabolizable energy values of the ingredients as outlined by NRC (1971). The composition of the experimental rations used and prices of individual ingredients are shown on Table 1. A thirteenth ration consisted of a commercial broiler ration containing 23% protein (Experiment 1) or a broiler finisher ration containing 20% protein (Experiment 2). In Experiment 1, day-old chicks averaging 45 g per chick were used and the experiment was terminated when the birds were five weeks old. In Experiment 2, the birds were fed the ration found optimum from Experiment 1 for 6 weeks before they were used to determine the requirements for energy and protein. The birds weighed approximately 1060 g per chicken when they were placed on the experimental treatments. The experiment was terminated when the birds were nine weeks old. At the end of Experiment 2, 10 chickens per replicate were randomly selected and slaughtered for carcass evaluation. All data collected during the experiments were subjected to analysis of variance and significance of differences assessed at 5% level of significance (Steel and Torrie, 1960).
829
.83
.83
.328
.83
.334
.323
1.22
1.22
1.22 .317
.83
1.22
.82
.75
.95 .69
26.1 2800 1.16
23.1 2800 1.06
.84 .62
20.1 2800
.30 .50
.1Q .50
.30 .50
.30 .50
.05
2.00 1.00
.05
2.00 1.00
44.45 39.20 5.00 7.50
.05
4
2.00 1.00
50.00 29.65 9.00 7.50
55.55 20.10 13.00 7.50
3
.05
2
2.00 1.00
61.10 10.55 17.00 7.50
17.1 2800
1
.30 .50
59.45 11.80 14.50 7.50 2.95 2.00 1.00
.352
.83
1.22
.84 .62
17.1 3000
5
.30 .50
.348
.83
1.23
.95 .68
.30 .50
48.35 30.90 6.50 7.50 2.95 2.00 1.00
.342
.83
1.23
.75
23.1 3000 1.05
(%)
7
Rations
53.90 21.35 10.50 7.50 2.95 2.00 1.00
20.1 3000
6
26.
. .
42. 40. 2. 7. 2. 2. 1.
. .
. 1.
1.
3000
8
Costs are based on prices of ingredients during period of experiment.
Supplied per kilogram ration: vitamin A, 10,000 IU; vitamin D 3 2000 ICU; vitamin E, 5 IU; vitamin K, 2.24 panthothenate, 10 mg; niacin, 25 mg; choline chloride, 350 mg; folic acid, 1 mg; manganese, 56 mg; zinc, 50 mg; co 125 mg; terramycin, 100 mg.
Yellow corn Groundnut cake Wheat bran Fish meal Palm oil Bone meal Periwinkle shell Common salt Premix a Calculated analysis: Crude protein (%) ME (kcal/kg diet) Lysine (%) Methionine (%) Calcium (%) Phosphorus (%) Cost," $/kg ration
Ingredients
TABLE 1. Composition of rations used in Experiments 1 and 2
om http://ps.oxfordjournals.org/ at Florida Atlantic University on February 26, 2015
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PROTEIN AND ENERGY FOR BROILER CHICKENS TABLE 2. Prices of ingredients and composition of rations ued in Experiment 3 Ingredients price/metric ton Experiment 1 and 2
Ingredients
d
Experiment 3
467 203 117
343 187 109 935 866 156 156 347 1948
Composition of rations (Experiment 3)
48.35 30.90 6.50 7.50 2.95 2.00 1.00
1091 1351 L56 156 519
Finisher ration
Starter ration - (%)
53.85 24.70 9.45 5.00 2.95 2.25 1.00 .30 .50
.30 .50
1948
23.1 3000 1.05
20.1 3000
.75
.82 .65
1.23
1.23
.83
.83
.435
.424
See Table 1.
of these data (Table 6) showed that the dietary protein levels did not significantly affect weight gain and feed consumption. The significant effects of protein levels on feed efficiency were linear at the 1% level. The differences between protein levels of 17, 20, and 23% were not
significant, nor were the differences significant in feed efficiency between protein levels of 20, 23, and 26%. The differences in feed cost per kilogram gain were significant, the trend being linear at the 1% level. The differences in feed cost per kilogram gain between protein levels of
TABLE 3. Effects of varying protein and energy levels on performance of starting broiler chicks (0 to 5 weeks, Experiment l)a
Ration no.
Protein level
Energy level (kcal/kg diet)
2800 2800 2800 2800 3000 3000 3000 3000 3200 3200 3200 3200 13 Commercial broiler starter 1 2 3 4 5 6 7 8 9 10 11 12
17 20 23 26 17 20 23 26 17 20 23 26
Average weight gain (g)
Feed consumption (g feed/bird)
EFC
(g/feed g gain)
Feed cost/kg live weight gain ($)
654 789 838 838 661 800 854 839 667 800 841 798 785
1617 1688 1668 1755 1645 1668 1662 1622 1649 1668 1635 1514 1730
2.48 2.14 1.99 2.10 2.48 2.08 1.94 1.94 2.38 2.08 1.94 1.90 2.10
.83 .70 .64 .66 .87 .73 .67 .66 .89 .76 .70 .67 .92
a Average maximum temperature 30.6 C; average minimum temperature, 14.0 C; average relative humidity, 11.5%
Downloaded from http://ps.oxfordjournals.org/ at Florida Atlantic University on February 26, 2015
Yellow corn Groundnut cake Wheat bran Fish meal Palm oil Bone meal Periwinckle shell Common salt Premixa Calculated analysis: Crude protein (%) ME (kcal/kg diet) Lysine (%) Methionine (%) Calcium (%) Phosphorus (%) Cost, $/kg ration
($)
OLOMU AND OFFIONG
832
TABLE 4. Analysis of variance for data obtained from Experiment 1 Mean squares df
Weight gain
Treatments (T) Protein level (P) P linear P quadratic P cubic Energy level (E) E linear E quadratic PX E
11 3 1 1 1 2 1 1 6
11514.70** 41282.94** 87511.86** 36201.21** 135.74 297.51 38.72 556.31 369.64
6777.62 3889.80 100.06 10023.78 1545.57 13052.98 25821.08 283.87 6129.73
EFC
Feed cost/ kg gain
.096** .306** .781** .132** .006 .045* .083** .007 .007
.015** .052** .137** .017** .001 .003 .004 .001 .001
*(P<.05). **(P<.01).
20, 23, and 26% were not significant while the lowest protein level (17%) significantly increased feed cost per kilogram gain. Dietary energy levels did not signifcantly affect weight gain, feed consumption, and feed cost per kilogram gain. Feed consumption, however, tended to decrease with increase in dietary energy level. The significant effects exerted by dietary energy levels on feed efficiency were linear at the 1% level. Feed efficiency improved significantly when the energy was increased from 2800 to 3000 kcal/kg diet. The improvement obtained when the energy was further increased from 3000 to
3200 kcal/kg diet was not significant. There were no significant interactions between the protein and energy levels in all the parameters studied. The effects of dietary treatments on mortality were minimal (less than 1%) and did not follow any particular trend. The commercial ration gave the lowest weight gain, poorest feed efficiency, and highest feed cost per kilogram of gain. Dietary treatments did not exert any significant effects on the percentages of carcass plus neck, gizzard, liver, and heart (Table 7). Experiment 3. Summarized in Table 8 are
TABLE 5. Effects of varying protein and energy levels on performance of finishing broiler chickens (6 to 9 weeks, Experiment 2)a
Ration no.
Protein level
Energy level (kcal/kg diet)
2800 2800 2800 2800 3000 3000 3000 3000 3200 3200 3200 3200 13 Commercial broiler finisher
1 2 3 4 5 6 7 8 9 10 11 12
17 20 23 26 17 20 23 26 17 20 23 26
Average weight gain (g)
Feed consumption (g feed/bi rd)
EFC
792 845 878 902 846 939 938 962 824 932 932 890 708
2484 2550 2593 2466 2382 2508 2549 2456 2239 2409 2368 2364 2268
3.13 3.04 2.96 2.78 2.82 2.68 2.72 2.56 2.72 2.58 2.55 2.66 3.20
(g feed/g gain)
Feed cost/kg live weight gain ($)
1.01 .97 .92 .86 .97 .90 .89 .83 .98 .92 .89 .92
1.31
Average maximum temperature, 32.3 C; average minimum temperature, 18.9 C; relative humidity, 13.75%.
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Source
Feed consumption
83 3
PROTEIN AND ENERGY FOR BROILER CHICKENS TABLE 6. Analysis of variance for data obtained from Experiment 2. Mean squares df
Weight gain
Treatment (T) Protein level (P) P linear P quadratic P cubic Energy level (E) E. linear E quadratic PX E
11 3 1 1 1 2 1 1 6
4905.19 5321.82 11662.41 4030.04 273.01 11419.62 16965.06 5874.19 2525.40
11923.97 4605.02 404.54 12312.99 1097.53 28718.04 57435.72 .359 9985.43
EFC
Feed cost/ kg gain
.073** .053* .149** .004 .007 .282** .497** .068 .013
.006* .015** .043** .001 .001 .004 .001 .006 .002
*(P«.05). **(P«.01).
the results of Experiment 3. As compared to the group fed the starter ration up to market weight, weight gains of the birds were only significantly depressed when the birds were changed from starter to finisher ration at less than three weeks of age. Comparable weight gains with the control ration (Treatment 1) were obtained when the birds were fed starter ration for 5 or 6 weeks (Treatment 7 or 8) before being changed to the finisher ration. Weight gains obtained on Treatments 1, 7, and 8 were significantly better than those on Treatment 2 (finisher ration). Feed consump-
tion, feed efficiency, and feed cost per kilogram of gain were not significantly affected by dietary treatment. DISCUSSION The trend of improving weight gains and feed efficiency with increasing dietary protein up to 23% for starting broiler chicks is in agreement with previous findings in the tropics (Olomu, 1976). Similar improvement in weights and feed efficiency as the dietary protein level increased from 14% to 24% had also been
TABLE 7. Effects of varying protein and energy levels on carcass dressing percentages of broiler chickens (Experiment 2)a
Ration
Protein level
no.
(%)
Energy level (kcal/kg diet)
Carcass + neck
Gizzard
1 2 3 4 5 6 7 8 9 10 11 12
17 20 23 26 17 20 23 26 17 20 23 26
2800 2800 2800 2800 3000 3000 3000 3000 3200 3200 3200 3200
71.52 67.02 69.62 68.41 68.88 70.15 70.44 68.90 69.71 68.10 68.52 69.58 67.17
2.48 2.27 2.16 2.18 2.44 2.27 1.98 2.00 2.07 2.16 2.18 2.16 2.26
13 Commercial broiler finisher l
All column values were not significantly different .(P<.05).
(">)
Liver
Heart
2.05 2.10 1.93 2.10 2.17 2.07 1.72 1.80 1.92 2.00 1.88 2.06 2.40
.676 .606 .654 .642 .716 .672 .584 .616 .618 .628 .619 .616 .654
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Source
Feed consumption
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OLOMU AND OFFIONG TABLE 8. Effects of time of change from broiler chicken starter ration to broiler chicken finisher ration (Experiment 3)1
Treatment no.
Finisher3 ration (weeks)
Average weight gain (g)
Feed consumption (g/bird)
EFC (g feed/g gain)
Feed cost/kg live weight gain ($)
0-9 1 -9 2-9 3 -9 4-9 5- 9 6-9
1928 a 1739 c 1768bc 1743 c 1856abc 1849abc 1928 a 1919 a
4693 4497 4510 4486 4681 4660 4791 4769
2.43 2.58 2.56 2.58 2.52 2.52 2.49 2.44
1.06 1.09 1.09 1.09 1.08 1.06 1.06 1.06
0-9 0 - 1 0-2 0-3 0-4 0-5 0-6 a
' ' c Column values with same superscript are not significantly different (P<.05).
1
Average maximum temperature, 28.8 C: average minimum temperature, 19.7 C; average relative humidity, 17%. 2 Period for which chicken broiler starter ration was fed. 3 Period for which chicken broiler finisher ration was fed.
reported by Babatunde and Fetuga (1976). The level of protein (23%) found optimum in this. study may thus be considered optimum for starting broiler chicks in Nigeria and is in agreement with the recommendation for some temperate countries (NRC, 1971). The results obtained in the present studies also agree with previous findings (Farrell et al., 1973; Olomu, 1976) that there is an optimum energy concentration in a ration beyond which performance of chicks does not appear to improve and, in some cases, actually deteriorates. In the present study with starting chicks, no statistically significant improvement in weight gain, feed consumption, and feed cost per kilogram gain were recorded for diets containing over 2800 kcal/kg diet. There was, however, a significant improvement in feed efficiency when the energy level was increased from 2800 to 3000 kcal/kg diet and no further significant improvement when the energy was increased from 3000 to 3200 kcal/kg diet. The optimum energy level for broiler chicks in the drier Guinea Savanna zone of Nigeria may thus be set at 2800 to 3000 kcal/kg diet in agreement with levels recommended for the more humid forest areas of Nigeria (Olomu, 1976). The recommended energy level is lower than that (3200 kcal/kg diet) recommended for some temperate countries by NRC (1971) and that (3100 kcal/kg diet) assumed by ARC (1975) as optimum. It is possible that broiler chicks perform better at lower dietary energy levels in the tropics
because of the higher environmental temperature which probably calls for lower energy needs to maintain basal metabolism. This may be true irrespective of whether the birds are raised in the humid forest zones of Nigeria (Olomu, 1976) or in the drier Guinea Savanna zones of Nigeria (present studies). The study with finishing broiler chickens indicates an obvious advantage of the ration containing 3000 kcal/kg diet over other rations in terms of at least weight gain and feed cost per kilogram of liveweight gain. No further improvement in feed efficiency was obtained when the energy level was increased from 3000 to 3200 kcal/kg diet. Protein levels above 20% did not exert any additional advantage. No published information with finishing broiler chickens in Nigeria is available at present to compare with the present results. The recommended protein level, however, agrees with that recommended for some temperate countries, but the energy level is lower than that recommended (3200 kcal/kg) for some temperate countries (NRC, 1971). The present results with finishing broiler chickens also indicate that within the range of protein and energy tested, it is difficult to alter the dressing percentages of the carcass plus neck and the giblets by dietary alteration of protein and energy. The results of the third experiment indicate that broiler chickens should not be changed
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1 2 3 4 5 6 7 8
Starter 2 ration (weeks)
PROTEIN AND ENERGY FOR BROILER CHICKENS
concentrates that will give a final energy level that is consistent with optimum broiler production in Nigeria and that is lower than that found optimum in temperate zones. ACKNOWLEDGMENTS
The authors wish to thank Saka Nuru, Director, National Animal Production Research Institute for permission to publish this paper. The assistance of S. A. S. Olorunju in statistical analysis is acknowledged. REFERENCES Agricultural Research Council, 1975. The nutrient requirements of farm livestock. No. 1, Poultry. 2nd ed. (rev.) ARC, London. Babatunde, G. M., and B. L. Fetuga, 1976. Determination of the minimum crude protein requirements of broiler starters and finishers in the tropics. Nigerian J. Anim. Prod. 3:126—138. Farrell, D. J., R. B. Cumming, and J. B. Hardaker, 1973. The effects of dietary energy concentration on growth rate and conversion of energy to weight gain in broiler chickens. Brit. Poultry Sci. 14:329-340. National Research Council, 1971. Nutrient requirements of poultry. 6th ed. Nat. Acad. Sci., Washington, DC. Olomu, J. M., 1976. Determination of optimum protein and energy levels for broiler chicks in the tropics. Nigerian J. Anim. Prod. 3:177-183. Olomu, J. M., A. R. Robblee, and D. R. Clandinin, 1974. Effects of processing and amino acid supplementation on the nutritive value of rapeseed for broilers. Poultry Sci. 53:175-184. Olomu, J. M., A. R. Robblee, and D. R. Clandinin, 1975. Utilization of full fat rapeseed and rapeseed meals in ration for broiler chicks. Can. J. Anim. Sci. 55:461-469. Steel, R. G. D., and Torrie, J. H., 1960. Principles and procedures of statistics. McGraw-Hill Book Company, Inc., New York.
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from broiler starter rations to broiler finisher rations earlier than 3 weeks of age. The best time to change seemed to be 5 or 6 weeks of age. No data are available at the moment in Nigeria to compare with the present results, although the time of change agrees with that recommended for some temperate countries by NRC (1971). It is also interesting to note that the broiler starter ration could be fed for the whole period without any added cost in terms of feed cost per kilogram of diet. At the recommended protein and energy levels, the performance of chickens fed the broiler starter was as good as that of chickens fed broiler starters reared in North America on a similar protein but a higher energy level by Olomu et al. (1974, 1975). At 9 weeks of age, weights and feed conversion obtained were also similar to those outlined for temperate zones by NRC (1971). The implications of the present and previous studies become pertinent in view of the lack of feed standards in Nigeria. A committee set up by the Nigerian Federal Government is already working on drawing up feed standards for the country but is being limited in its work by the lack of adequate data on optimum levels of nutrients for farm animals. Since the present and previous studies were carried out in two different areas of the country, representing two different ecological zones, the data obtained may be used to set up preliminary feed standards for broiler chickens, at least with respect to protein and energy. The results may also prove useful to foreign feed enterpreneurs who export their concentrates to Nigeria. It may be necessary in the future that such enterpreneures formulate
835