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Essential Minerals for Chicks and Laying Hens
ESSENTIAL MINERALS FOR CHICKS AND LAYING HENS D. C. KENNARD Ohio Agricultural Experiment Station, Wooster
1 Jour. Agr. Research (1920) 18: 390. Amer. Jour. Physiology (1922) 59: 298. -'Pori-TBY SCIENCE, Vol. I, Feb.-Mar. (1922). 3 Jour. Amer. Assoc, of Instr. and Inv. of Poultry Husbandry (1920) 15: 20. 4 Mo. Bui., Ohio Agr. Exp. Sta., Nov.-Dec. (1922).
109
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The role of minerals in the diet for chickens is of prime importance although it often receives but secondary consideration. Laying hens not only have the usual requirements for growth, maintenance and body functions, but have an additional calcium requirement essential for the process of egg shell formation. In face of this heavy demand for minerals and the fact that the feed for chickens must be composed largely of concentrates, the majority of which are of vegetable origin and low in minerals, it is evident that much attention need be given the mineral factor in such rations if deficiencies in this respect are to be avoided. The fact that concentrates from vegetable sources are low in calcium, sodium, and chlorine was first established by work with other animals. Experiments conducted with growing chicks^ and laying hens' show that grains, seeds, or vegetable products aside from roughages fail to meet the mineral requirements of chickens also, and that the failure of the ration derived entirely from vegetable sources is due to the deficiency of minerals more than any other factor. When this deficiency is corrected by a suitable mineral supplement, vegetable protein concentrates may be successfully employed to replace meat scraps in whole or in part. In other words, work previously reported^ showed that baby chicks would live but a short time on a ration in which soybean meal replaced meat scraps, Avhereas the soybean meal ration with a mineral supplement proved equal to the meat scraps ration. For laying hens'* a simple mineral addition doubled the value of rations in which soybean meal, peanut meal or cotton-
110
POULTRY
SCIENCE
It will be noted that the calcium-phosphorus compound constitutes the larger proportion of the mixture. This compound may be secured from different sources in a variety of forms, such as bone meal in its different forms and modifications as raw bone, steamed bone, soluble or slightly acidulated bone meal, precipitated bone meal, bone ash, and ground rock phosphate (floats) ; each of which have given results about equally effective. The calcium carbonate may be obtained as a by-product in the manufacture of soap at a low cost, or it may be substituted by a high grade (95% CaCOs) ground agricultural limestone. There appears to be no need for an expensive complicated mineral mixture when this simple inexpensive combination has proven so effective. The tendency of commercial manufacturers of mineral mixtures is to use a variety of products which make a complicated formula and a higher selling price. Compounds of
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
seed meal constituted the protein supplement; whereby the value of the vegetable protein concentrates proved comparable though not equal to meat scraps. Aside from the general facts that vegetable concentrates are almost invariably low in essential minerals and that a simple inexpensive mineral addition will in most cases double their value for growth of egg production and that the laying hen needs a special supplement of calcium carbonate in suitable form for egg shells or reduced egg production will result, there are some special phases of the question of essential minerals for chickens which may be considered at this time. A simple inexpensive mineral mixture effective.—A mineral supplement for general economic use should be simple and inexpensive and easily procured. This naturally suggests : what are the essential minerals? At the beginning of the work a rather complicated formula Avas used.^ When it was found that the results secured were of practical significance it seemed desirable to eliminate any of the non-essentials, so as to develop a more simple and inexpensive supplement better adapted for practical use. It was f ound^ that three ingredients appeared to supply the essentials: bone meal or rock phosphate (floats) 60; calcium carbonate or ground limestone (95% CaCOj) 20; and sodium chloride 20.
ESSENTIAL
MINERALS
FOR
POULTRY
111
TABLE I ·— EGG PRODUCTION AS AFFECTED BY A REDUCED A M O U N T OF MEAT SCRAPS SUPPLEMENTED BY ADDITIONAL MINERALS
Basal Ration* Plus
Breed
Relative feed consumption Eggs first year Per cent per bird mortality Time grain Per cent meat scraps to total 1 yr. as mash consumed grain & mash
Leghornst 122 Barred Roeks§ 134
10.00 6.66
1.17 1.47
9.25. 8.11
119 Meat scraps 10% Leghorns Mineral m i x t u r e t Barred Rocks 139
14.00 23.33
1.27 1.40
4.40 4.17
105 Meat scraps 10% Legliorns No mineral mixt. Barred Rocks 114
14.00 23.33
1.39 1.87
4.91 3.49
Meat scraps 20%
*Mash: Ground corn 2, and std. wheat middlings 2; Grain : Corn 3, wheat 2. t Bone meal 60, calcium carbonate 20, and sodium chloride 20. $ 50 to each ration. § 30 to each ration.
The results (Table I) in case of both Leghorns and Rocks indicate that the minerals rather than the protein are the first limiting factor when the meat scraps is radically reduced. Thus it may be that additional minerals in connection with the reduced quantity of meat scraps may enable some reduction without
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
doubtful value may be included instead of adhering to materials serving only specific purposes. May the meat scraps be reduced hy use of a mineral supplement? Since the usual 50% protein meat scraps serves as a double supplement of protein and minerals, which becomes the first limiting factor, the protein or the minerals when the meat scraps are reduced below minimum requirements? If minerals become the first limiting factor, it would seem that a suitable mineral supplement might be used in connection with a less amount of meat scraps with equal effectiveness, and thereby reduce the cost of the ration. The experiments.-—As it is customary to use 20 per cent meat scraps in the mash for layers, this amount was used in the control ration. In the second ration, the mash contained 10 per cent meat scraps and 2 per cent mineral mixture ; whereas in the third ration, 10 per cent of meat scraps was added to the mash, but the mineral mixture omitted. The test involved fifty Wliite Leghorns and thirty Barred Rocks to each ration.
112
POULTRY
SCIENCE
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lowering egg production. The results are not conclusive and do not warrant any change in the common practice of using 20 per cent meat scraps in the mash for egg production. They do, however, offer some suggestions. In the first place, the intake of meat scraps depends as much upon the proportion of grain to mash consumed as upon the amount of meat scraps in the mash. The proportion of mash the birds eat depends upon its palatibility, the method of feeding, and condition of the birds. If, as is sometimes the ease, three or four times as much grain as mash is consumed, 20 per cent meat scraps in the mash would undoubtedly fail to supply the essential mineral matter and possibly the protein would be deficient since the meat scraps would constitute only 4 or 5 per cent of the entire ration. It would thus appear that the per cent of meat scraps should be based upon the total of grain and mash rather than upon the mash only. In other words, if meat scraps (50 per cent protein) are to supply the required minerals and protein, they should constitute not less than 7.5 to 10 per cent of the total grain and mash. It will be observed in Table I that the Rocks ate a larger proportion of grain than the Leghorns. This is according to expectation, since they have larger bodies and more grain is required for heat and energy. The grain was fed sparingly in the morning and a full feed was given at night. With both breeds the groups receiving 10 per cent meat scraps in mash without additional minerals ate less mash in proportion to grain than the other lots. Whether the mineral mixture made the mash more palatable or whether the increased egg production stimulated greater consumption of mash, is a question. There was little difference between the consumption of the mash containing 10 per cent meat scraps and 2 per cent mineral mixture and that containing 20 per cent meat scraps. The mortality of birds was practically the same in all the groups. When should a mineral supplement he usedf—It is doubtful if any advantage is to be derived from adding a mineral supplement to the ration for chickens, having access to direct sunlight and an abundance of green feed, if milk products or animal packing house by-products are liberally fed. These products are usually good sources of essential minerals. For example, 50 per cent protein meat scraps contains about 20 to 25 per cent
ESSENTIAL
MINERALS
FOR POULTRY
Hg
5 Twenty-sixth Annual Report, N. Y. Agr. Exp. Sta., Part III (1908).
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
inorganic matter and 10 to 12 per cent milk solids. I t is only for certain special purposes that additional minerals may be expected to yield positive results, viz. : when it is desired to replace or partially substitute animal protein products by vegetable protein concentrates; or if a high protein, say 75 to 85 per cent meat scraps is to be used; and when the animal protein is reduced or eliminated for purpose of retarding sexual development of early hatched pullets. Recently special grades of meat scraps have appeared on the market which carry 75 to 85 per cent protein. In other words, they are essentially a meat or protein product and are low in minerals. Since it is an established fact that the usual grade of meat scraps, 50 per cent protein, carries two supplements (mineral and protein) of equal importance, it is at once evident that the special grades containing 75 to 85 per cent protein and but 5 to 10 per cent mineral matter will serve as a protein rather than a mineral supplement. In view of the vital function of minerals it would seem that the 50 per cent protein meat scraps might readily prove the more valuable than the high per cent protein product unless minerals are added to the latter. To avoid any chance of a mineral deficiency, the high per cent protein meat scraps should be supplemented by 2 or 3 per cent (by M^eight of total mash) of the mineral mixture. In order that a ration may be modified for special purposes it is sometimes desired to reduce the protein concentrate partiallj»· or entirely. Reduction of the animal protein automatically reduces the minerals. It may sometimes be desirable to radically reduce the protein, but under no circumstances should the minerals be reduced below minimum requirements. Therefore, if the animal feed concentrates, carrying the principal source of minerals, are to be reduced, the corresponding reduction of minerals should be corrected by means of a mineral supplement. This applies particularly to early hatched pullets in which it is desired to secure body growth, but retard sexual development. Calcium for egg shells.—More than one-third of the total dry matter of an egg is mineral matter, chifly the calcium qorbonate of the shell. Wheeler^ of the Geneva Station, reported that ordinary feed and water supplied but 15 per cent of the lime re-
POULTRY
114
SCIENCE
TABLE I I — LIMESTONE GKIT ( 9 5 % CaCOa) v s . OY-STEE S H E L L S — ΤΗΙΚΤΎ B^vREED ROCK PULLETS TO E A C H R A T I O N *
Basal Eationf Plus ' Oyster Shells and Mica Grit
'
Experiment Eggs per Number Bird (1-12 mo.i Ϊ34 — . , >^^__^^ ^^_^ ^go
Per Cent Mortality 6.66 20.00
Limestone Grit
fl-12 mo. | 2 - 1 0 mo.
112 94
23.23 20.00
Oyster Shells and Limestone Grit
(1-12 mo. ) 2-10 mo
132 115
20.00 10 00
Mica Grit
(1-12 mo. 2-10 mo.
100 80
16.66 6.66
* Birds confined indoors until June in botli experiments. t Grain : Corn 3, wheat 2. . Mash : Meat scrap 1, ground corn 2, std. wheat mids. 2. Î October 10, 1922, to October 10. 1923. § October 10, 1923, to August 1, 1924.
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quirement for egg shell formation. More recently, experiments conducted at the Wisconsin and Ohio stations show that if the balance of the requirement is not supplied a reduction in egg production results somcAvhat comparable to the omission of the protein concentrate. Since reduced egg production rather than production of shell-less (soft-shelled) eggs resulted when the hens were denied lime for egg shells, contrary to popular, opin ion, the so-called soft-shelled eggs appear to be due to complica tions not directly related to a deficiency of calcium carbonate for egg-shell formation. Limestone versus oyster shells.—Since oyster shells are avail able locally in but few of, the poultry producing states, other sources of lime for this purpose are desirable. In most sections of the country tliere is an abundance of high-grade limestone. Since limestone as well as oyster shells contains a high per cent of calcium corbonate (95 per cent) may it not serve the purpose as well? For some light on this question, an experiment was con ducted with thirty Barred Rock pullets to each of four different groups as indicated in Table. The first year's experiment has been, completed, and the test is being repeated this year with another set of pullets with the results given in Table I I . These results show that calcium carbonate in a suitable form is about as essential as any other part of the ration for successful
ESSENTIAL
MINERALS
FOR POULTRY
II5
TABLE I I I — S I Z E AND CRUSHING STKENGTH OF EGGS AS AFFECTED BY O i i i s s i o i i OP OYSTEK S H E L L S FROM RATION FOE LAYERS*
Basal Rationf and Oyster Shells and Mica Grit
Average Wt. Exp. Number of Per IDozeii No. Eggs Weighed in Eggs Ounces 1
479
22.7
2
289
23.3
1
389
22.2
2
223
23.8
1
494
22.4
2
244
23.3
1
443
20.6
2
180
21.4
Limestone Grit Oyster Shells and Limestone Grit Mica Grit
Number of Eggs Used in Crushing Tests
Average Crushing Test in Pounds
1st test—29 2nd test—23 3rd test—57
39.0Î 21.5§ • 20.811
1st test—22 2nd test—15
39.0Î 19.7§
1st test—16 2nd test—16
37.0ί 18.7§
1st test—16 2nd test—15 3rd test—43
33.0Î 16.3§ 18.41
* Birds confined indoors until June, t Grain: Corn 3. wheat 2. Mash : Ground corn 2, std. Avlieat middlings 2, and meat scraps 1. t Ends of eggs placed in sockets, i Ends of eggs placed on flat surface. ΐ Same as second test, but after birds were out of doors.
placed endAvise in sockets so shaped as to distribute the pressure over a considerable area of the egg. In the t\vo other tests the eggs were placed endwise against a flat surface on each end in0 Wisconsin Bui. 350 (1923). τ Research Bui. 250, Kentucky Agr. Exp. Sta. (1924).
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egg production. The poultry keeper's egg crop will be cut short about the same if he neglects to provide a suitable form of Calcium carbonate for egg shells as if he attempts to omit the protein concentrate, such as meat scraps, milk, etc., from the ration for layers. While the results do not ofEer conclusive evidence as to the relative value of oyster shells and limestone grit, the indications are that oyster shells are superior. An average of three similar tests conducted at the Wisconsin Station" showed the relative value of limestone grit (dolomitie) to be 71 per cent that of oyster shells, which is practically the same as obtained by the Ohio Station. These results are contrary to those reported by Buekner, Martin and Peter,'' in which they found limestone equal to oyster shells in an eight months' test. The crushing test of eggs was made by use of a machine used for breaking strength of bones. In the iirst test the egg was
Xlg
POULTRY
SCIENCE
SUMMARY
The deficiency of essential minerals in vegetable protein concentrates appeared to be more responsible than any other factor for their inferiority as compared with meat scraps. A simple mineral supplement composed of bone meal 60, cal-
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
stead of the sockets. In all tests the ends of eggs were against one-sixteenth inch thickness of soft rubber. While nature usually tends to produce a complete product, especially as regards reproduction of either animal or vegetable organisms, or deny reproduction altogether, in case of hens fed a ration deficient in lime for egg shells there is evidence of a compromise on two points: the size of egg, and the texture of shells. (Table III.) If the texture of shell is affected it would seem that in a few extreme cases soft-shelled eggs may occasionally be due to lack of lime. The size of eggs from pullets not receiving oyster shells or limestone grit were consistently less than the others, being about two ounces per dozen less in weight in both experiments. While the data obtained from crushing tests is only preliminary, yet it rather consistently indicates that lack of lime causes weaker shells. The relative crushing strength of eggs from the mica grit lot in the three tests stated in per cent was 85, 76 and 89 respectively, when compared to the eggs received from the group which received oyster shells given an assumed value of 100. The fact that oyster shells are more relished by the fowls may be an advantage in that a greater intake results. Also the oyster shells are more readily pulverized than most grades of limestone. The question might arise, Avould it be an advantage to add finely ground limestone to the mash ? The evidence available indicates that the calcium carbonate for shell formation must be fed in the form of grit or coarse material rather than fine. If fine material is put in hoppers, the hens do not relish it. At the same time, the necessary amount could not be added to the mash without seriously interfering with the birds' digestive functions. It is questionable if more than 1 per cent powdered calcium carbonate should be added to the mash, whereas 6 or 7 per cent would be required to meet the hen's requirement during egg production.
ESSENTIAL
MINERALS
FOR POULTRY
H'J
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cium carbonate 20, and sodium chloride 20, proved effective for the correction of rations deficient in minerals. When the meat scraps (50 per cent protein) supplying both proteins and minerals was reduced below minimum requirements for laying hens, it seems that the minerals rather than the proteins were the first limiting factor. Rations containing a small amount of meat scraps should be supplemented with minerals. This would also apply to rations in which meat scraps containing 75 to 85 per cent protein is used. When laying hens were not supplied with calcium carbonate in suitable form for egg shells, reduced egg production resulted. Oyster shells appeared to be superior to limestone (95% Ca CO3) grit.
1 Jour. Agr. Research (1920) 18: 390. Amer. Jour. Physiology (1922) 59: 298. -'Pori-TBY SCIENCE, Vol. I, Feb.-Mar. (1922). 3 Jour. Amer. Assoc, of Instr. and Inv. of Poultry Husbandry (1920) 15: 20. 4 Mo. Bui., Ohio Agr. Exp. Sta., Nov.-Dec. (1922).
109
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
The role of minerals in the diet for chickens is of prime importance although it often receives but secondary consideration. Laying hens not only have the usual requirements for growth, maintenance and body functions, but have an additional calcium requirement essential for the process of egg shell formation. In face of this heavy demand for minerals and the fact that the feed for chickens must be composed largely of concentrates, the majority of which are of vegetable origin and low in minerals, it is evident that much attention need be given the mineral factor in such rations if deficiencies in this respect are to be avoided. The fact that concentrates from vegetable sources are low in calcium, sodium, and chlorine was first established by work with other animals. Experiments conducted with growing chicks^ and laying hens' show that grains, seeds, or vegetable products aside from roughages fail to meet the mineral requirements of chickens also, and that the failure of the ration derived entirely from vegetable sources is due to the deficiency of minerals more than any other factor. When this deficiency is corrected by a suitable mineral supplement, vegetable protein concentrates may be successfully employed to replace meat scraps in whole or in part. In other words, work previously reported^ showed that baby chicks would live but a short time on a ration in which soybean meal replaced meat scraps, Avhereas the soybean meal ration with a mineral supplement proved equal to the meat scraps ration. For laying hens'* a simple mineral addition doubled the value of rations in which soybean meal, peanut meal or cotton-
110
POULTRY
SCIENCE
It will be noted that the calcium-phosphorus compound constitutes the larger proportion of the mixture. This compound may be secured from different sources in a variety of forms, such as bone meal in its different forms and modifications as raw bone, steamed bone, soluble or slightly acidulated bone meal, precipitated bone meal, bone ash, and ground rock phosphate (floats) ; each of which have given results about equally effective. The calcium carbonate may be obtained as a by-product in the manufacture of soap at a low cost, or it may be substituted by a high grade (95% CaCOs) ground agricultural limestone. There appears to be no need for an expensive complicated mineral mixture when this simple inexpensive combination has proven so effective. The tendency of commercial manufacturers of mineral mixtures is to use a variety of products which make a complicated formula and a higher selling price. Compounds of
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
seed meal constituted the protein supplement; whereby the value of the vegetable protein concentrates proved comparable though not equal to meat scraps. Aside from the general facts that vegetable concentrates are almost invariably low in essential minerals and that a simple inexpensive mineral addition will in most cases double their value for growth of egg production and that the laying hen needs a special supplement of calcium carbonate in suitable form for egg shells or reduced egg production will result, there are some special phases of the question of essential minerals for chickens which may be considered at this time. A simple inexpensive mineral mixture effective.—A mineral supplement for general economic use should be simple and inexpensive and easily procured. This naturally suggests : what are the essential minerals? At the beginning of the work a rather complicated formula Avas used.^ When it was found that the results secured were of practical significance it seemed desirable to eliminate any of the non-essentials, so as to develop a more simple and inexpensive supplement better adapted for practical use. It was f ound^ that three ingredients appeared to supply the essentials: bone meal or rock phosphate (floats) 60; calcium carbonate or ground limestone (95% CaCOj) 20; and sodium chloride 20.
ESSENTIAL
MINERALS
FOR
POULTRY
111
TABLE I ·— EGG PRODUCTION AS AFFECTED BY A REDUCED A M O U N T OF MEAT SCRAPS SUPPLEMENTED BY ADDITIONAL MINERALS
Basal Ration* Plus
Breed
Relative feed consumption Eggs first year Per cent per bird mortality Time grain Per cent meat scraps to total 1 yr. as mash consumed grain & mash
Leghornst 122 Barred Roeks§ 134
10.00 6.66
1.17 1.47
9.25. 8.11
119 Meat scraps 10% Leghorns Mineral m i x t u r e t Barred Rocks 139
14.00 23.33
1.27 1.40
4.40 4.17
105 Meat scraps 10% Legliorns No mineral mixt. Barred Rocks 114
14.00 23.33
1.39 1.87
4.91 3.49
Meat scraps 20%
*Mash: Ground corn 2, and std. wheat middlings 2; Grain : Corn 3, wheat 2. t Bone meal 60, calcium carbonate 20, and sodium chloride 20. $ 50 to each ration. § 30 to each ration.
The results (Table I) in case of both Leghorns and Rocks indicate that the minerals rather than the protein are the first limiting factor when the meat scraps is radically reduced. Thus it may be that additional minerals in connection with the reduced quantity of meat scraps may enable some reduction without
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
doubtful value may be included instead of adhering to materials serving only specific purposes. May the meat scraps be reduced hy use of a mineral supplement? Since the usual 50% protein meat scraps serves as a double supplement of protein and minerals, which becomes the first limiting factor, the protein or the minerals when the meat scraps are reduced below minimum requirements? If minerals become the first limiting factor, it would seem that a suitable mineral supplement might be used in connection with a less amount of meat scraps with equal effectiveness, and thereby reduce the cost of the ration. The experiments.-—As it is customary to use 20 per cent meat scraps in the mash for layers, this amount was used in the control ration. In the second ration, the mash contained 10 per cent meat scraps and 2 per cent mineral mixture ; whereas in the third ration, 10 per cent of meat scraps was added to the mash, but the mineral mixture omitted. The test involved fifty Wliite Leghorns and thirty Barred Rocks to each ration.
112
POULTRY
SCIENCE
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
lowering egg production. The results are not conclusive and do not warrant any change in the common practice of using 20 per cent meat scraps in the mash for egg production. They do, however, offer some suggestions. In the first place, the intake of meat scraps depends as much upon the proportion of grain to mash consumed as upon the amount of meat scraps in the mash. The proportion of mash the birds eat depends upon its palatibility, the method of feeding, and condition of the birds. If, as is sometimes the ease, three or four times as much grain as mash is consumed, 20 per cent meat scraps in the mash would undoubtedly fail to supply the essential mineral matter and possibly the protein would be deficient since the meat scraps would constitute only 4 or 5 per cent of the entire ration. It would thus appear that the per cent of meat scraps should be based upon the total of grain and mash rather than upon the mash only. In other words, if meat scraps (50 per cent protein) are to supply the required minerals and protein, they should constitute not less than 7.5 to 10 per cent of the total grain and mash. It will be observed in Table I that the Rocks ate a larger proportion of grain than the Leghorns. This is according to expectation, since they have larger bodies and more grain is required for heat and energy. The grain was fed sparingly in the morning and a full feed was given at night. With both breeds the groups receiving 10 per cent meat scraps in mash without additional minerals ate less mash in proportion to grain than the other lots. Whether the mineral mixture made the mash more palatable or whether the increased egg production stimulated greater consumption of mash, is a question. There was little difference between the consumption of the mash containing 10 per cent meat scraps and 2 per cent mineral mixture and that containing 20 per cent meat scraps. The mortality of birds was practically the same in all the groups. When should a mineral supplement he usedf—It is doubtful if any advantage is to be derived from adding a mineral supplement to the ration for chickens, having access to direct sunlight and an abundance of green feed, if milk products or animal packing house by-products are liberally fed. These products are usually good sources of essential minerals. For example, 50 per cent protein meat scraps contains about 20 to 25 per cent
ESSENTIAL
MINERALS
FOR POULTRY
Hg
5 Twenty-sixth Annual Report, N. Y. Agr. Exp. Sta., Part III (1908).
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
inorganic matter and 10 to 12 per cent milk solids. I t is only for certain special purposes that additional minerals may be expected to yield positive results, viz. : when it is desired to replace or partially substitute animal protein products by vegetable protein concentrates; or if a high protein, say 75 to 85 per cent meat scraps is to be used; and when the animal protein is reduced or eliminated for purpose of retarding sexual development of early hatched pullets. Recently special grades of meat scraps have appeared on the market which carry 75 to 85 per cent protein. In other words, they are essentially a meat or protein product and are low in minerals. Since it is an established fact that the usual grade of meat scraps, 50 per cent protein, carries two supplements (mineral and protein) of equal importance, it is at once evident that the special grades containing 75 to 85 per cent protein and but 5 to 10 per cent mineral matter will serve as a protein rather than a mineral supplement. In view of the vital function of minerals it would seem that the 50 per cent protein meat scraps might readily prove the more valuable than the high per cent protein product unless minerals are added to the latter. To avoid any chance of a mineral deficiency, the high per cent protein meat scraps should be supplemented by 2 or 3 per cent (by M^eight of total mash) of the mineral mixture. In order that a ration may be modified for special purposes it is sometimes desired to reduce the protein concentrate partiallj»· or entirely. Reduction of the animal protein automatically reduces the minerals. It may sometimes be desirable to radically reduce the protein, but under no circumstances should the minerals be reduced below minimum requirements. Therefore, if the animal feed concentrates, carrying the principal source of minerals, are to be reduced, the corresponding reduction of minerals should be corrected by means of a mineral supplement. This applies particularly to early hatched pullets in which it is desired to secure body growth, but retard sexual development. Calcium for egg shells.—More than one-third of the total dry matter of an egg is mineral matter, chifly the calcium qorbonate of the shell. Wheeler^ of the Geneva Station, reported that ordinary feed and water supplied but 15 per cent of the lime re-
POULTRY
114
SCIENCE
TABLE I I — LIMESTONE GKIT ( 9 5 % CaCOa) v s . OY-STEE S H E L L S — ΤΗΙΚΤΎ B^vREED ROCK PULLETS TO E A C H R A T I O N *
Basal Eationf Plus ' Oyster Shells and Mica Grit
'
Experiment Eggs per Number Bird (1-12 mo.i Ϊ34 — . , >^^__^^ ^^_^ ^go
Per Cent Mortality 6.66 20.00
Limestone Grit
fl-12 mo. | 2 - 1 0 mo.
112 94
23.23 20.00
Oyster Shells and Limestone Grit
(1-12 mo. ) 2-10 mo
132 115
20.00 10 00
Mica Grit
(1-12 mo. 2-10 mo.
100 80
16.66 6.66
* Birds confined indoors until June in botli experiments. t Grain : Corn 3, wheat 2. . Mash : Meat scrap 1, ground corn 2, std. wheat mids. 2. Î October 10, 1922, to October 10. 1923. § October 10, 1923, to August 1, 1924.
Downloaded from http://ps.oxfordjournals.org/ at North Dakota State University on June 16, 2015
quirement for egg shell formation. More recently, experiments conducted at the Wisconsin and Ohio stations show that if the balance of the requirement is not supplied a reduction in egg production results somcAvhat comparable to the omission of the protein concentrate. Since reduced egg production rather than production of shell-less (soft-shelled) eggs resulted when the hens were denied lime for egg shells, contrary to popular, opin ion, the so-called soft-shelled eggs appear to be due to complica tions not directly related to a deficiency of calcium carbonate for egg-shell formation. Limestone versus oyster shells.—Since oyster shells are avail able locally in but few of, the poultry producing states, other sources of lime for this purpose are desirable. In most sections of the country tliere is an abundance of high-grade limestone. Since limestone as well as oyster shells contains a high per cent of calcium corbonate (95 per cent) may it not serve the purpose as well? For some light on this question, an experiment was con ducted with thirty Barred Rock pullets to each of four different groups as indicated in Table. The first year's experiment has been, completed, and the test is being repeated this year with another set of pullets with the results given in Table I I . These results show that calcium carbonate in a suitable form is about as essential as any other part of the ration for successful
ESSENTIAL
MINERALS
FOR POULTRY
II5
TABLE I I I — S I Z E AND CRUSHING STKENGTH OF EGGS AS AFFECTED BY O i i i s s i o i i OP OYSTEK S H E L L S FROM RATION FOE LAYERS*
Basal Rationf and Oyster Shells and Mica Grit
Average Wt. Exp. Number of Per IDozeii No. Eggs Weighed in Eggs Ounces 1
479
22.7
2
289
23.3
1
389
22.2
2
223
23.8
1
494
22.4
2
244
23.3
1
443
20.6
2
180
21.4
Limestone Grit Oyster Shells and Limestone Grit Mica Grit
Number of Eggs Used in Crushing Tests
Average Crushing Test in Pounds
1st test—29 2nd test—23 3rd test—57
39.0Î 21.5§ • 20.811
1st test—22 2nd test—15
39.0Î 19.7§
1st test—16 2nd test—16
37.0ί 18.7§
1st test—16 2nd test—15 3rd test—43
33.0Î 16.3§ 18.41
* Birds confined indoors until June, t Grain: Corn 3. wheat 2. Mash : Ground corn 2, std. Avlieat middlings 2, and meat scraps 1. t Ends of eggs placed in sockets, i Ends of eggs placed on flat surface. ΐ Same as second test, but after birds were out of doors.
placed endAvise in sockets so shaped as to distribute the pressure over a considerable area of the egg. In the t\vo other tests the eggs were placed endwise against a flat surface on each end in0 Wisconsin Bui. 350 (1923). τ Research Bui. 250, Kentucky Agr. Exp. Sta. (1924).
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egg production. The poultry keeper's egg crop will be cut short about the same if he neglects to provide a suitable form of Calcium carbonate for egg shells as if he attempts to omit the protein concentrate, such as meat scraps, milk, etc., from the ration for layers. While the results do not ofEer conclusive evidence as to the relative value of oyster shells and limestone grit, the indications are that oyster shells are superior. An average of three similar tests conducted at the Wisconsin Station" showed the relative value of limestone grit (dolomitie) to be 71 per cent that of oyster shells, which is practically the same as obtained by the Ohio Station. These results are contrary to those reported by Buekner, Martin and Peter,'' in which they found limestone equal to oyster shells in an eight months' test. The crushing test of eggs was made by use of a machine used for breaking strength of bones. In the iirst test the egg was
Xlg
POULTRY
SCIENCE
SUMMARY
The deficiency of essential minerals in vegetable protein concentrates appeared to be more responsible than any other factor for their inferiority as compared with meat scraps. A simple mineral supplement composed of bone meal 60, cal-
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stead of the sockets. In all tests the ends of eggs were against one-sixteenth inch thickness of soft rubber. While nature usually tends to produce a complete product, especially as regards reproduction of either animal or vegetable organisms, or deny reproduction altogether, in case of hens fed a ration deficient in lime for egg shells there is evidence of a compromise on two points: the size of egg, and the texture of shells. (Table III.) If the texture of shell is affected it would seem that in a few extreme cases soft-shelled eggs may occasionally be due to lack of lime. The size of eggs from pullets not receiving oyster shells or limestone grit were consistently less than the others, being about two ounces per dozen less in weight in both experiments. While the data obtained from crushing tests is only preliminary, yet it rather consistently indicates that lack of lime causes weaker shells. The relative crushing strength of eggs from the mica grit lot in the three tests stated in per cent was 85, 76 and 89 respectively, when compared to the eggs received from the group which received oyster shells given an assumed value of 100. The fact that oyster shells are more relished by the fowls may be an advantage in that a greater intake results. Also the oyster shells are more readily pulverized than most grades of limestone. The question might arise, Avould it be an advantage to add finely ground limestone to the mash ? The evidence available indicates that the calcium carbonate for shell formation must be fed in the form of grit or coarse material rather than fine. If fine material is put in hoppers, the hens do not relish it. At the same time, the necessary amount could not be added to the mash without seriously interfering with the birds' digestive functions. It is questionable if more than 1 per cent powdered calcium carbonate should be added to the mash, whereas 6 or 7 per cent would be required to meet the hen's requirement during egg production.
ESSENTIAL
MINERALS
FOR POULTRY
H'J
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cium carbonate 20, and sodium chloride 20, proved effective for the correction of rations deficient in minerals. When the meat scraps (50 per cent protein) supplying both proteins and minerals was reduced below minimum requirements for laying hens, it seems that the minerals rather than the proteins were the first limiting factor. Rations containing a small amount of meat scraps should be supplemented with minerals. This would also apply to rations in which meat scraps containing 75 to 85 per cent protein is used. When laying hens were not supplied with calcium carbonate in suitable form for egg shells, reduced egg production resulted. Oyster shells appeared to be superior to limestone (95% Ca CO3) grit.