The Relation of Season of Freshening to Milk Production

Abstract

Milk yields for 22,212 Connecticut cows averaged highest for cows freshening in Feb. and lowest for cows freshening in July. The most favorable month of calving came later in the fall-winter season than had been found in studies in other areas. Production for cows calving in the most favorable month of freshening exceeded that in the least favorable month by 13.7%. This was much greater than found by Woodward in a 12-state analysis but less than was found in recent studies in New Hampshire, and about the same as found in New York. The association of milk yield with month of calving was similar for each of the 4 breeds[long dash]Guernsey, Holstein, Ayrshire, and Jersey. The association also was similar for each of the most important age groups, although the difference in yields between the most favorable and least favorable month of calving became relatively greater as age increased. In determining differences in yields associated with month of calving, statistical procedures taking into account the joint relationship of age with season of freshening were necessary. As the cows in Connecticut herds increased in age, a smaller proportion freshened in the fall months.