98 MASS. EXPERIMENT STATION BULLETIN 388 



The Effect of an Excess of Calcium in the Diet. (M. S. Gutowska and R. T. 

 Parkhurst.) The results of this experiment showed that an excess of calcium in 

 the ration of laying hens lowered the production value of the diet, and that 3.95 

 percent of calcium in the diet of laying hens having a normal dietary level of 

 phosphorus and ample vitamin D intake was excessive. However, there was no 

 significant difference in the egg shell breaking strength, the average egg weight, 

 and the fertility and hatchability of eggs between the groups of birds receiving 

 the varying levels of calcium. 



The importance of a control of the mineral balance of laying rations by means 

 of chemical analysis at regular intervals is suggested. 



The Value of Pulverized Calcite Flour as a Source of Calcium for Laying Hens. 



(M. S. Gutowska and R. T. Parkhurst.) The object of this experiment was to 

 compare qualitatively two rations with different sources of calcium: pulverized 

 plain calcite and oyster shell meal, at the same quantitative level. The man- 

 ganese content of the rations was estimated to be close to the assumed optimum 

 for laying pullets. 



The data obtained from two flocks of 24 Rhode Island Red pullets during 12 

 months showed no significant differences in production, body and egg weight, 

 feed efficiency, egg shell breaking strength, hatchability, and fertility. The egg 

 quality was equal in the two flocks. 



It was concluded that pulverized plain calcite is as good a source of calcium as 

 oyster shell meal for lading pullets; but its biological value as a mineral supple- 

 ment for laying hens is not higher than that of oyster shell meal. 



The Phosphatase Activity as a Factor of Calcium Deposition and Egg-Shell 

 Formation. (M. S. Gutowska and R. T. Parkhurst, with the cooperation of 

 E. M. Parrott and R. M. Verberg of the Chemistry Department.) Phosphatase 

 activity as a factor of shell formation is studied by the determination of plasma 

 and oviduct phosphatase activity. Four groups of hens, good and poor producers, 

 with good and poor egg shell, are being compared in this regard. The phos- 

 phatase activity is determined according to a modification of King-Armstrong 

 method. 



Electric Brooding. (W. C. Sanctuary in cooperation with Professor C. I. 

 Gunness of the Engineering Department.) The use of soil cable under 4 inches 

 of sawdust litter materially reduced moisture content of litter, when used con- 

 tinuously, but at an excessive cost. The use of insulation plus restricted ventila- 

 tion also reduced the moisture content of the litter materially, but not so much 

 as the continuous use of the soil cable. The use of damp (40 percent moisture) 

 sawdust from the start of brooding produced no deleterious results except for a 

 large number of crooked toes thought to be due to cold floors. Because of high 

 moisture content, the litter froze into a solid block on cold nights. 



Combining Meat and Egg Production. (W. C. Sanctuary and J. H. Vondell.) 

 The standardization of body weight in Barred Plymouth Rocks at 6 pounds by 

 December 1 has been well established. The 1938 generation had a mean weight 

 just below 6 pounds. The generations of 1939 and 1940 had a mean weight just 

 a trifle above 6 pounds. There has been some improvement in meat quality as 

 measured by fleshing upon the breasts at 8 weeks of age and later as adults. 

 One adult male of the 1941 generation has approached the extreme "broad- 

 breasted" type now produced in one variety of turkey. Egg production has 

 improved also, three 300-eggers having been produced in the last two years 

 largely because of improvement in intensity (rate) of production. 



