SECTIONAL TRANSACTIONS.— M. 431 



Tuesday, August 10. 



10. Prof. R. A. Berry. — Suhstitnlion of Silage for Roots in the Feeding of 



Dairy Cows. 



11. Sir Arnold Theiler, K.C.M.G., Dr. H. H. Green and Dr. P. J. Du 



ToiT. — Minimum Mineral Requirements of Cattle. 



The experiments recorded in this paper were undertaken with the object of 

 determining the physiological muiimum requirements of cattle for phosphorus, 

 calcium, sodium, potassium, and chlorine ; main stress was laid on phosphorus and 

 calcium. Incidentally the recent views (of Marek and others), that the ratio of the 

 various minerals in the food is of dominant importance, were tested experimentally, 

 and found to be incorrect for cattle. 



The sixteen heifers used (in pairs) in the eight experiments described were kept 

 on a basic ration extremely low in mineral constituents. To this ration different 

 minerals were added in the various experiments. 



The two animals kept on low phosphorus (about 5 gm. Pj O5 daily) and low 

 calcium (about 7 gm. CaO) remained stunted and developed the disease known as 

 ' Styfsiekte ' (stiff-sickness) in South Africa. The addition in another experiment of 

 calcium to the ration (5 gm. Pj O5, 29 gm. CaO) did not modify the adverse effect of 

 low phosphorus, but seemed to intensify it : both animals developed • styfsiekte,' 

 although the mineral ratio, according to Marek, must be considered favourable. 

 With the addition of bonemeal (100 gm. per day, bringing total P2 O5 to 28 gm., and 

 total CaO to 37 gm.) to the ration, the animals developed normally and, at the end of 

 eighteen months, were in excellent condition. Bran (high in phosphorus, low in 

 calcium) had the same effect : two animals receiving 2 lb. per day (total P., O5 24 gm., 

 total CaO 8-2 gm.) showed no sign of deficiency disease in spite of the low ratio of 

 CaO to P2O5. 



Two animals from whose diet salt was omitted, thus receiving very little sodium 

 (2 gm. Na.jO per day !) and chlorine (5 gm.), but whose diet was supplemented with 

 phosphorus and calcium (100 gm. bonemeal per day) developed normally. The 

 addition of potassium chloride to the ration of two other heifers (44 gm. K»0 as 

 against 2 gm. NajO) caused no disturbance. 



One of the outstanding features of the above experiments was that all animals 

 which received sufficient phosphorus throve in spite of the practically entire absence 

 of vitamines from their diet. Two heifers which served as vitamine control and 

 received a daily ration of green forage developed no better than the others. The 

 sonclusion seems justified that the vitamine requirements of cattle are negligible. 



12. Discussion on The Feeding of the Dairy Cow. 



Prof. F. B. Wood, F.R.S., Mr. R. Boutflour, Mr. W. R. Peel. 



