4 MASS. EXPERIMENT STATION BULLETIN 321 



vice versa. The rations were reversed three times so that each group received each 

 ration for two different periods of forty days each. Results have been reckoned 

 from the last thirty days of each period, the first ten days being considered pre- 

 liminary, to allow the cows to become accustomed to the change in feed and to 

 offset any lag in the effect of the previous ration on milk production. Table 2 

 shows the schedule of the experiment. 



The composition of the grain mixtures is given in Table 3. 



Table 1. — Status of the two groups of cows at the beginning of the 



experiment. 



Group A Group B 

 Breed: 



Shorthorns 3 2 



Ayrshires 1 2 



Holsteins 4 4 



Guernseys 3 2 



Jerseys 1 2 



Average age 5 years 4 months 5 years 6 months 



Average weight 1148 pounds 1147 pounds 



Average stage in lactation 81 days 77 days 



Average daily milk yield 32.8 pounds 32.8 pounds 



Average butter fat 4.18 per cent 4.35 per cent 



Table 2. — Schedule of feeding periods. 



Period 



Nov. 19 — Dec. 28, inclusive 

 Dec. 29 — Feb. 6, inclusive 

 Feb. 7 — Mar. 18, inclusive 

 Mar. 19 — Apr. 27, inclusive 



Ration fed to 

 Group A 

 Soybean-cottonseed 

 Tankage 



Soybean-cottonseed 

 Tankage 



Ration fed to 

 Group B 

 Tankage 



Soybean-cottonseed 

 Tankage 

 Soybean-cottonseed 



Table 3. — Formulas of grain mixtures. 



Soybean- 

 Ingredients cottonseed Meal Tankage 



Mixture Mixture 



(Pounds) (Pounds) 



Wheat bran 400 400 



Ground oats 500 500 



Hominy feed 640 640 



Soybean meal (41% protein). . . . 200 



Cottonseed meal (41% protein). 200 



Corn starch ... 100 



Tankage ... 340 



Steamed bone meal 40 



Salt 20 20 



TOTAL 2000 2000 



