Too Much Limestone Lowers Digestibility of Both Protein and Energy in Silage. 



In the course of the many experiments at this Station seeking the best 

 possible method of harvesting and storing home-grown roughages for winter 

 feeding, it was found that the digestibility and utilization of the protein of 

 the silage was lower than that of either the mow-cured or field-cured hays 

 from the same field. Because of the lower digestibility of the silage, it seemed 

 desirable to try to find out what caused this depression. It was thought that 

 pulverized limestone, a common mixed concentrate ingredient, might neu- 

 tralize the acidity of the silage and perhaps improve its digestibility. The 

 feeding of the limestone at a rate of 100 g. per day, however, caused a fur- 

 ther drop of 6 to 8% in the digestibility of the protein in the silage. This 

 very significant drop in digestibility of the protein posed the very important 

 question as to the possible harm inclusion of lower amounts of minerals might 

 cause to the digestibility of the ration. With that in view, an experiment was 

 set up whereby the animals received limestone at levels of 0, 50, and 100 

 grams per day. 



The animals receiving the 100 grams of limestone per day during the 

 second experiment also had a significantly lower digestibility of protein than 

 the animals receiving no limestone, thus confirming the results of the previ- 

 ous year. There was no significant difference in the digestibility of the pro- 

 tein by the animals receiving the 50 grams of pulverized limestone as com- 

 pared to the animals receiving no limestone. 



From the results of this study, it appears that the feeding of pulverized 

 limestone to dairy heifers being fed silage rations does not increase digesti- 

 bility of either the protein or energy. While rates of limestone up to 50 grams 

 per day were not detrimental, higher rates were. 



N. F. Colovos, H. A. Keener 

 H. A. Davis, A. E. Teeri 



Influence of the Ration on Vitamin Synthesis in the Rumen. 



The low quality of late-cut hay with respect to nicotinic acid and ribo- 

 flavin was reflected in the decreased excretion of these vitamins by cows fed 

 the hay. For the other rations fed, nicotinic acid excretion was unaffected, 

 while the excretion values for riboflavin indicated that silage and possibly 

 cane molasses favor the rumen or intestinal synthesis of this vitamin. Rumen 

 synthesis of the thiamine probably is of considerable importance in ruminant 

 nutrition, and the feeding of silage appears to favor this synthesis. 



A. E. Teeri. D. Josselyn 

 N. F. Colovos, H. A. Keener 



Does Sulfur Dioxide Affect Vitamin Synthesis in the Rumen? 



Preliminary results indicate that synthesis of thiamine, by rumen micro- 

 organisms, is greatly increased when the ration contains sulfur dioxide — 

 preserved silage. Hence, even though S0 2 destroys much of the thiamine in 

 the silage, increased rumen synthesis of the vitamin counteracts the resultant 

 deficiency in the ration. 



The thiamine synthesis — favoring action of S0 2 is nullified by the 

 presence of limestone but unaffected by molasses. 



A similar synthesis — favoring action of SO2 has been noted in con- 

 nection with nicotinic acid, but in this case the effect is much less pronounced. 



A. E. Teeri, D. Josselyn 

 N. F. Colovos, H. A. Keener 

 24 



