634 THE PHYSIOLOGY OF REPRODUCTION 



the lambing statistics for various flocks of Scottish sheep for the 

 years 1905, 1906, and 1907, it is shown that the percentage of 

 lambs born was, as a general rule, highest among sheep which had 

 been subjected to a process of artificial stimulation. The method 

 adopted was to feed the ewes upon turnips, oats^ maize, dried grains, 

 or other additional food at the tupping time and for about three 

 weeks previously, while maintaining them upon grass only during 

 the greater part of the year. Some flocks, however, received a 

 limited supply of extra food (generally turnips) during gestation, 

 and especially during the later part of this period. The additional 

 supply of turnips, which are specially rich in carbohydrate material, 

 was found to be in no way detrimental to fertility, but rather the 

 reverse, when accompanied by other food (pasture), and so not taken 

 in excess. The statistics show that in the flocks treated in the way 

 described, the percentage of lambs per ewes ^ was almost invariably 

 in excess of the average percentage for flocks which received no 

 special treatment, while the percentage of barren ewes was usually 

 also less in the specially fed flocks. In some cases the number of 

 lambs per ewes in the flushed flocks was nearly 200 per cent. 

 Among flocks belonging to the same breeds (Border Leicester or 

 half-bred Border Leicester) which received no sort of special 

 treatment, the average proportion of lambs per ewes was between 

 150 and 160 per cent., while flocks which were run upon superior 

 pasture at the approach of the sexual season, without being otherwise 

 specially fed, generally produced a slightly larger percentage of ■ 

 Iambs. The twins appear almost invariably to have been born early 

 during lambing, thus showing that the generative activity of the 

 ewes tends to be greatest at the commencement of the sexual season. 

 It has proved more difficult to obtain definite information 

 concerning the effects of flushing in one year upon the fertility of 

 the ewes in subsequent seasons. The more usual experience of 

 flockmasters seems to be that flushing is not in any way prejudicial 

 to breeding stock unless it is overdone, the object of the process 

 being to get the animals in an improving condition without 

 permitting them to put on too much fat. If the artificial feeding 

 is excessive and the sheep are forced to depend for the remainder 

 of the year upon a mere sustenance diet, it is easy to understand 

 that they would tend to deteriorate, and their subsequent fertility 

 become impaired, owing probably to a higher frequency of follicular 

 degeneration. It is seemingly for such a reason that some flock- 

 masters regard the practice of flushing as one altogether to be 

 deprecated. There is some evidence, however, that if sheep are 

 specially fed in one season, the process must be repeated in the next, 



1 That is to say, the number of lambs per 100 ewes. 



