702 FEEDS AND FEEDING 



among breeders that breeding immature females retards the growth of 

 the young mother and diminishes her ultimate size, and also that it 

 results in offspring which are smaller and less thrifty. To study this 

 matter Mumford and colleagues have conducted extensive investigations 

 covering over 12 years at the Missouri Station, 26 in which some sows and 

 their offspring in the following generations have been bred as early as 

 they came in heat. Other sows and their offspring have been bred for 

 the first time at 18 months of age, and still others not until they were 30 

 months of age. All were fed liberally on well-balanced rations. 



It was found that immature sows bred at 5 months of age and twice 

 a year thereafter may be expected to develop into somewhat smaller 

 animals at maturity than if they had not been bred until later. This 

 results not from any checking of the growth during gestation, for preg- 

 nancy tended to increase the rate of growth in young sows. The smaller 

 size was due to the lactation period being a heavy drain on the dam, 

 which checked the growth of the immature sow while nursing her young. 

 Mumford concludes: "The diminished size of mature sows bred at an 

 early age has no very important practical significance in the production 

 of swine for market, since the difference in size at maturity between 

 animals bred at a very young age and those bred at a later age, is not 

 significant. ' ' 



With reference to the effect of early breeding on the offspring of 

 young mothers he states, 27 "The only apparent effect upon the offspring 

 of very young mothers is the effect which would be anticipated as the 

 result of the failure on the part of the young mother to supply a sufficient 

 amount of milk for the most rapid growth of the offspring. This effect 

 is not commercially significant, and as an average of many years of 

 experiment it seems probable that it requires about ten days longer for 

 the offspring of very young sows to reach a weight of 250 Ibs., than for 

 the offspring of mature animals to reach the same weight. ' ' 



Had early breeding been combined with scant feeding, the result on 

 both the dams and the offspring would have unquestionably been marked. 



1037. Number of litters a year; fall pigs. Whether his sows should 

 have one or two litters a year is a problem of great importance that 

 every swine raiser must decide. The answer should depend on the local 

 conditions, especially on the winter climate, the shelter which can be 

 furnished, and the feeds available. In mild climates the sows should 

 raise two litters as a rule, for this will reduce the cost of pork production 

 materially. (1041) The fall litters in such sections should prove as 

 satisfactory as the spring pigs, for they can be furnished pasture until 

 late in the year and, in the southern states, even during the winter. 

 Often even better profits can be made from fall pigs under favorable 

 conditions than from the spring litters, for they reach market in the 

 spring or summer when the prices are usually materially higher than in 

 autumn. 



28 Mo. Res. Bui. 45. "Information to the authors. 



