The Effect of Season of the Year and Advancing Lactation upon Milk Yield of Jersey Cows

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Abstract
The Florida station dairy herd earlier consisted of both registered and high grade Jersey cows, the majority of which were bred and raised on the farm. As described recently (3), the herd is located in the middle of the north end of the Florida peninsula, under an environment which varies less than does that of many dairy regions, due to proximity of large bodies of water and the general direction of the prevailing winds. Feeding practises have been relatively uniform over the period of years for which records were studied (1917 to 1932, inclusive), except for modifications in mineral con- tent brought about mainly by inclusion of bone-meal in the concentrates. The rations and feeding practises followed were described in Florida station technical bulletin 262. REVIEW OF LITERATURE The influence of the season of freshening on total milk yield has been the object of a number of investigations. McDowell (13) assembled records of 64 cow testing associations between 1910 and 1920, comprising 10,870 cow-years. He found that the fall-fresh cows were the highest producers, followed by those calving during winter, summer and spring. Cannon (4) tabulated 68,000 records of Iowa dairy herd improvement association cows of all breeds for the years 1925 to 1930, and noted that the cows fresh during November produced the most milk, and those fresh during June yielded the least milk during the year. Wylie (18) analyzed 2,900 Jersey Register of lVierit records completed in the United States in 1921, an.d noted that those Jerseys fresh in July produced the most, and those calving in November were the next highest in milk production. The group of cows that calved during August were lowest in milk yields.
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