ARID AGRICULTURE. 339 



time being 330 day-. A mare will raise colts 

 until more than twenty-five years of age. 



THE cow Puberty in the cow occurs at from nine 



months old to two years old. Dairy breeds may 

 be bred very young, but beef cattle should no't 

 he allowed to have calves before two and one- 

 half years old. Cows usually come in heat 

 every twenty -one clays, and the periods of heat 

 last from one to four days, the average being 

 about thirty-six hours. The gestation period of 

 the cow is nine months, the average length of 

 time being 183 days. Heifer calves usually drop 

 in 182 days, and bull calves take one or two days 

 longer. Young heifers with first calf, and small 

 cows often go a day or two less. 



SHEEP AND The lamb sometimes reaches puberty as early 



GOATS as f[ ve months of age. With most breeds of 



sheep the heat or rutting season only comes in 

 the fall months. It usually begins about the 

 middle of September, lasts about twenty-four 

 hours, and recurs every fourteen to sixteen days 

 until the end of December. Some breeds, like 

 the Dorsett, may be made to breed at other sea- 

 sons of the year. This is much influenced by 

 the character of feed and treatment. The pe- 

 riod of gestation in the sheep and the goat is five 

 months, the average time being 148 or 149 days. 

 The Rambouillet carries its lambs one or two 

 days less time than the American Merino, and 



