168 



Gestation of Cows. 



It appears also that the number of breeding females is less con- 

 siderably than the number of males, and to the number of males 

 ought generally to be added, as animals that will not breed, the 

 females who are twins with males. I have heard and believe, 

 that in some cases a cow-calf, twin with a bull, will breed ; but 

 in no instance in which I have bred twins of different sexes has 

 the female been a breeding heifer. The number of breeding 

 heifers from these 764 cows was 354 ; the number of bull-calves 

 422 ; and the number of heifers twin with bulls, usually called 

 fremartins, 11. 



There is a prevalent belief among farming men, and I believe 

 farmers, that, when the time of gestation of a cow is longer than 

 usual, the produce is generally a male calf. I must confess that 

 I did not believe this to be the case, but this table shows that 

 there is some foundation for the opinion. In order fairly to try 

 this, the cows who calved before the 260th day, and those who 

 calved after the 300th, ought to be omitted as being anomalous 

 cases, as well as the cases in which twins were produced ; and it 

 will then appear that, from the cows whose period of gestation did 

 not exceed 286 days, the number of cow-calves produced was 233, 

 and the number of bull-calves 234 ; while, from those whose 

 period exceeded 286 days, the number of cow-calves was only 90, 

 while the number of bull-calves was 152. 



I am not aware of any other conclusions which may be deduced 

 from the collection of cases which I have made, and, as I have 

 already stated, I do not see in Avhat manner the knowledge of 

 these conclusions can be practically useful ; but any information 

 elucidating the physiology of cattle may be advantageous in some 

 way which at the present moment I do not foresee. I think it 

 most probable that these results will be found generally applicable ; 

 but it must always be recollected that they are derived from the 

 observations of one breeder only ; and though I think it likely that 

 no other man in this country has made similar observations on so 

 large a number of individual cases, still it must be admitted that 

 there is a possibility that, from the circumstance of my experience 

 having been confined to one variety of cattle and to one farm, 

 there may be found a difference in the results to be deduced 

 from a similar experiment, if it was tried on land of different 

 quality, in a different locality, and upon cattle of some other 



21 calved between the 240th and 270th day, the mean term being 259^ 

 544 ditto 270th „ 299th „ „ 282 



10 ditto 299th „ 321st „ „ 303 



" In most cases, therefore, between 9 and 10 montbs may be assumed as the 

 usual period; though, with a bull-calf, she has been generally observed to 

 go about 41 weeks, and a_^ few days less with a feraale."_ Vol. ii. p. 438. — 

 F. Burke. 



