126 



FEEDS AND FEEDING 



Bull-Emmett standards for fattening lambs 



It will be noted that the requirements for protein are expressed in 

 terms of crude protein instead of true protein, as in the Armsby stand- 

 ards. Bull and Emmet t state that the figures for lambs weighing 110 to 

 150 Ibs. are only approximations, owing to the small amount of data 

 available for animals of these weights. It will be noted that as the lambs 

 become more mature the amount of protein required per 1,000 Ibs. live 

 weight grows less. 



176. Ration for maintaining the steer. To illustrate the method of 

 using the Armsby standards and table of net energy values, let us com- 

 pute a ration for maintaining a mature steer weighing 1,000 Ibs., when 

 neither gaining nor losing weight, assuming that there are available corn 

 stover, oat straw, dent corn, and cottonseed meal. According to the 

 standard, an animal of this weight requires 0.5 Ib. digestible protein and 

 6.0 therms of net energy. As corn stover and oat straw are much cheaper 

 than the concentrates, let us first see how nearly a ration of these rough- 

 ages alone will meet the requirements. Suppose that we select for a 

 trial ration 10 Ibs. of corn stover and 8 Ibs. of oat straw. This ration will 

 furnish the dry matter, digestible protein and net energy shown in the 

 table. 



First trial ration for maintaining 1,000-lb. steer 



This ration furnishes enough net energy but is deficient in digestible 

 protein. Corn, which is high in net energy but low in protein, will not 

 improve the ration, while cottonseed meal, which is rich in protein, will 

 make up the deficiency. Let us therefore substitute 1 Ib. of choice 

 cottonseed meal for 2 Ibs. of oat straw. We then have : 



