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“performance index” of growing chickens
Research Notes "PERFORMANCE I N D E X " OF GROWING CHICKENS H . R.
BIRD
Department of Poultry Husbandry, University of Wisconsin, Madison, Wisconsin (Received for publication March 26, 1955)
In commercial broiler production and in research on growth of chickens, it is common practice to compare groups with respect to weight and with respect to feed efficiency which is defined as the gain per unit of feed consumed. It often happens that groups are arranged in one sequence when compared on the basis of mean live weight and in an entirely different sequence when compared on the basis of efficiency. It then becomes desirable to make an over-all comparison that takes account of both weight and efficiency. Very frequently this is accomplished by multiplying mean live weight by efficiency or dividing mean live weight by feed conversion which is the reciprocal of efficiency. The resulting figure, designated the "performance index," "efficiency index," or "performance efficiency" has been used both by commercial broiler producers and by research workers (Lanson and Smyth, 1955; Wilder et al., 1955).
criticism. It would seem, however, that there is logical justification for the use of the "performance index," and the justification lies in the fact that research workers and producers are interested in two rates of gain, namely, rate of gain per unit of feed and rate of gain per unit of time. On this basis, the calculation of Wilder et al, becomes:
Wilder et al., after explaining that they obtained "performance efficiency" by multiplying weight gains by the reciprocal of the feed conversion figure and dividing by 100, stated, "While some persons hold that this calculation is invalid because it involves the weight gains twice along with the feed consumption, it nevertheless is a useful index in measuring over-all performance."
Performance index =
Performance index = Gain X
Gain Feed
=
Gain2 Feed
The writer has often heard the same
Performance index = Gain
Gain Unit
time-x-Unit
feed
100 Unit time was 8 weeks, unit feed was one gram, and gain was expressed in grams. Since Lanson and Smyth used average weight rather than average gain, expressed weight and feed in pounds, and multiplied by 100 rather than dividing by 100, their calculation becomes: Gain-(-initial weight
X-
Unit time Gain Unit feed
-X100
Unit time was 10 weeks, unit feed was 1 pound, and gain was expressed in pounds. In calculating performance index it is customary to give equal weight to gain per unit time and gain per unit feed. This practice appears to be justified by the report of McAllister and Bausman (1950). Their analysis of management practices in commercial broiler production indi-
1163
1164
RESEARCH NOTES
cated that the gain per pound of feed had a little more effect on net return than did gain per week, but the difference was small. REFERENCES Lanson, R. K., and J. R. Smyth, 1955. Pellets vs. mash plus pellets vs. mash for broiler feeding.
Poultry Sci. 34: 234-235. McAllister, W. T., and R. 0 . Bausman, 1950. Influence of management practices on cost of producing broilers in Delaware. Delaware Agr. Exp. Sta. Bui. 282. Wilder,O.H.M.,P.C.OstbyandB. R.Gregory, 1955. The nutritive value of meatscrap and tankage. Progress Report No. 20, American Meat Institute Foundation, Chicago.
THE RESTRICTION OF OOPORPHYRIN DEPOSITION ON EGG SHELLS BY DRUG FEEDING CECIL F. MCCLARY State College of Washington, Western Washington Experiment Station, Puyallup, Washington (Received for publication March 29, 1955)
The development, through research, of new growth stimulants and drugs for disease and parasite preventives and treatments in poultry might be expected to result in some "accidental" discoveries of fundamental value in research. One such discovery has resulted from the use of a new coccidiostat recommended for chickens under 12 weeks of age. The drug which is known by the trade name Nicarbazin (Merck) has the formula 4,4' dinitrocarbanilide, 2 hydroxy-4,6dimethylpyrimidine. Some indication of peculiar results of feeding this drug to certain breeds of laying hens prompted the work herein reported. In a preliminary test on the effect of nicarbazin on egg shell color, three White Rock hens were selected and initial individual egg shell color established. They were then moved to a small pen and changed from the conventional breeder ration to a ration containing .0125 percent nicarbazin. The hens were trapnested daily for seven days and the eggs were saved. The hens were then placed back on the coventional breeder ration and trapnesting was continued for four more days. The color of each egg laid from one day before drug feeding began until four
days after drug feeding ended, was recorded as to color grades according to a color standard supplied by Kosin (1954). Grade 1 was assigned to white eggs, grade 2 light cream, with each successive grade increasing in brown color intensity up to a medium dark brown egg at grade 6. Because of the many shades of brown color among eggs, all colors more intense than medium brown were also included in grade 6. Color grades for each hen's eggs by dates are listed in Table 1. It may be noted from Table 1 that some color change in egg shells was apparent within two days after the start of nicarbazin feeding. After three to four days on the drug, the egg shells had lost all of their brown surface color. One hen's eggs (hen #2890) were chalk white and the other two laid pink-white eggs that change to white with a green hue after long exposure to light. All eggs laid between the fourth TABLE 1.—Effect of Nicarbazin in diet on egg shell color of Single Comb White Plymouth Rock hens Days on drug Hen No.
0
1
2
3
4
5
Days off drug 6
7
1 2
3
4
6 6
5 6 6 6
Egg shell color score 2737 2857 2890
6 6 6
6
5 6 3
1 1 — 1 1 3 1 1 1 1 1 — 1 1 1
2 — —
— 6 —
BIRD
Department of Poultry Husbandry, University of Wisconsin, Madison, Wisconsin (Received for publication March 26, 1955)
In commercial broiler production and in research on growth of chickens, it is common practice to compare groups with respect to weight and with respect to feed efficiency which is defined as the gain per unit of feed consumed. It often happens that groups are arranged in one sequence when compared on the basis of mean live weight and in an entirely different sequence when compared on the basis of efficiency. It then becomes desirable to make an over-all comparison that takes account of both weight and efficiency. Very frequently this is accomplished by multiplying mean live weight by efficiency or dividing mean live weight by feed conversion which is the reciprocal of efficiency. The resulting figure, designated the "performance index," "efficiency index," or "performance efficiency" has been used both by commercial broiler producers and by research workers (Lanson and Smyth, 1955; Wilder et al., 1955).
criticism. It would seem, however, that there is logical justification for the use of the "performance index," and the justification lies in the fact that research workers and producers are interested in two rates of gain, namely, rate of gain per unit of feed and rate of gain per unit of time. On this basis, the calculation of Wilder et al, becomes:
Wilder et al., after explaining that they obtained "performance efficiency" by multiplying weight gains by the reciprocal of the feed conversion figure and dividing by 100, stated, "While some persons hold that this calculation is invalid because it involves the weight gains twice along with the feed consumption, it nevertheless is a useful index in measuring over-all performance."
Performance index =
Performance index = Gain X
Gain Feed
=
Gain2 Feed
The writer has often heard the same
Performance index = Gain
Gain Unit
time-x-Unit
feed
100 Unit time was 8 weeks, unit feed was one gram, and gain was expressed in grams. Since Lanson and Smyth used average weight rather than average gain, expressed weight and feed in pounds, and multiplied by 100 rather than dividing by 100, their calculation becomes: Gain-(-initial weight
X-
Unit time Gain Unit feed
-X100
Unit time was 10 weeks, unit feed was 1 pound, and gain was expressed in pounds. In calculating performance index it is customary to give equal weight to gain per unit time and gain per unit feed. This practice appears to be justified by the report of McAllister and Bausman (1950). Their analysis of management practices in commercial broiler production indi-
1163
1164
RESEARCH NOTES
cated that the gain per pound of feed had a little more effect on net return than did gain per week, but the difference was small. REFERENCES Lanson, R. K., and J. R. Smyth, 1955. Pellets vs. mash plus pellets vs. mash for broiler feeding.
Poultry Sci. 34: 234-235. McAllister, W. T., and R. 0 . Bausman, 1950. Influence of management practices on cost of producing broilers in Delaware. Delaware Agr. Exp. Sta. Bui. 282. Wilder,O.H.M.,P.C.OstbyandB. R.Gregory, 1955. The nutritive value of meatscrap and tankage. Progress Report No. 20, American Meat Institute Foundation, Chicago.
THE RESTRICTION OF OOPORPHYRIN DEPOSITION ON EGG SHELLS BY DRUG FEEDING CECIL F. MCCLARY State College of Washington, Western Washington Experiment Station, Puyallup, Washington (Received for publication March 29, 1955)
The development, through research, of new growth stimulants and drugs for disease and parasite preventives and treatments in poultry might be expected to result in some "accidental" discoveries of fundamental value in research. One such discovery has resulted from the use of a new coccidiostat recommended for chickens under 12 weeks of age. The drug which is known by the trade name Nicarbazin (Merck) has the formula 4,4' dinitrocarbanilide, 2 hydroxy-4,6dimethylpyrimidine. Some indication of peculiar results of feeding this drug to certain breeds of laying hens prompted the work herein reported. In a preliminary test on the effect of nicarbazin on egg shell color, three White Rock hens were selected and initial individual egg shell color established. They were then moved to a small pen and changed from the conventional breeder ration to a ration containing .0125 percent nicarbazin. The hens were trapnested daily for seven days and the eggs were saved. The hens were then placed back on the coventional breeder ration and trapnesting was continued for four more days. The color of each egg laid from one day before drug feeding began until four
days after drug feeding ended, was recorded as to color grades according to a color standard supplied by Kosin (1954). Grade 1 was assigned to white eggs, grade 2 light cream, with each successive grade increasing in brown color intensity up to a medium dark brown egg at grade 6. Because of the many shades of brown color among eggs, all colors more intense than medium brown were also included in grade 6. Color grades for each hen's eggs by dates are listed in Table 1. It may be noted from Table 1 that some color change in egg shells was apparent within two days after the start of nicarbazin feeding. After three to four days on the drug, the egg shells had lost all of their brown surface color. One hen's eggs (hen #2890) were chalk white and the other two laid pink-white eggs that change to white with a green hue after long exposure to light. All eggs laid between the fourth TABLE 1.—Effect of Nicarbazin in diet on egg shell color of Single Comb White Plymouth Rock hens Days on drug Hen No.
0
1
2
3
4
5
Days off drug 6
7
1 2
3
4
6 6
5 6 6 6
Egg shell color score 2737 2857 2890
6 6 6
6
5 6 3
1 1 — 1 1 3 1 1 1 1 1 — 1 1 1
2 — —
— 6 —