?A0 ANNUAL REPORT OF THE Off. Dor. 



the formation of those parts which are most highly prized. By se- 

 lection and skill In breeding, he has also relatively increased the pro- 

 portion of the most desirable parts. Not only is the amount of meat 

 produced from a given quantity of food greatly increased, but its 

 quality or value is also greatly enhanced. 



It is my thought to discuss with you, if possible, one phase of 

 economical meat production in swine; namely, the relationship be 

 tween age and growth, or age and meat production from food con- 

 sumed. It has been long known that the young of domestic animals 

 make relatively a much more rapid growth than do those animals 

 which are further advanced in their life's history, but not until 

 quite recent times have accurate data been determined with a suffi- 

 ciently large number of animals to give us anything like a general 

 law or principle. Since the establishment of the Federal Experiment 

 Stations, in 1887, numerous experiments have been made, which en- 

 able us to determine in advance the average development of a con- 

 siderable number of animals with a marked degree of certainty. 



A few years ago, Professor Henry, Director of the Wisconsin Ex- 

 periment Station, gathered together the results of American Ex- 

 periment Stations which pertained to the feeding of pigs at various 

 ages, and averaged those that were comparable and tabulated the 

 results. From these results, which were gathered from widely differ- 

 ing sources and made with a large number of animals, it is shown 

 that pigs during the first seven days after birth gain about seventy- 

 six per cent, of their total weight. During the third week, about 

 forty per cent. During the fifth week, about twenty-five per cent. 

 During the seventh week, about twenty-two per cent. During the 

 ninth week, about nineteen per cent. While the decrease in per- 

 centage gain, as the birth period is receded from, is fairly constant, 

 yet it does not decrease in proportion to the increase in total weight, 

 or as the age of the animal increases. That is, the percentage in- 

 crease in weight is most rapid immediately after birth. This grows 

 rapidly less for a few weeks and then more gradually less and less 

 until a time or period is reached when there is no further gain. From 

 experiments made with hundreds of older animals, the percentage 

 increase in weight has been quite accurately determined for aver- 

 age good conditions under which swine are usually kept. 



Pigs weighing thirty-eight and one-half pounds a piece showed an 

 increase of sixteen per cent, in one week; those weighing seventy- 

 eight pounds, an increase of seven per cent.; of one hundred and 

 twenty-eight pounds, six per cent.; of two hundred and seventy-one 

 pounds, three and eight-tenths per cent.; of three hundred and twenty 

 pounds, three and one-tenth per cent. These tests were made by a 

 number of Experiment Stations and with hundreds of animals. Some 

 of the averages were determined from more than a hundred trials 



