Most farm commodity futures declined on the nation's major exchanges today. The continuing bitter cold in some sections of the country and snow-clogged rural roads tended to influence some buying early, but the late profit taking turned prices around in several pits.

Early demand in grains was fairly active, and was led as usual by commercial interests. These included processors, exports, elevators and millers. Minutes after the opening - which has produced some irreguarl price levels - local professionals set into buying oats, corn and wheat, and prices rose from 1 1/2 to about 3 cents.

The weatheer was the major buying factor early in grains. Late in the session, the locals took profits and oats turned under previous closes, while the corn gain was about halved.

The Agriculture Department noted that soybeans, meal and oil prices would continue at firm to strong levels until the Brazilian soybean crop is marketed later this year. Then prices should ease. When the domestic harvest gets under the way, there should be a mild easing of prices, too. But any weather problems during the growing season could change the prices picture.

Prices in the soybean complex also were mixed to steady, then improved briefly under local buying. After about an hour, however, local professionals and some commission house orders introduced spreading activity. Old-crop, or nearby, contracts were bought because prices would continue at high levels, and new-crop, or deferreds, were sold because the brazilian crop will be in competition.

Old-crop soybeans advanced more than 7 cents, while deferreds fell as much. Soy meal and oil old and new crops also showed a disparity, but although beans and oil closed mixed, there was a gain of up to $2.50 a ton in meal. Iced broilers fell 1/2 cent a pound, largely under commercial and local liquidation.

Shell egg futures opened on a firm tone, the tumbled for losses up to 200points, the allowable daily limit. Some improvement in the weather where broiler production is high and concern that plentiful offerings now will be made influenced the selling. Sellers in live cattle futures also expected increase over Wednesday's cattle inventory report. Deliveries against the February contracts also were of some concern.

Live hogs fell 60 cents per hundredweight despite a steday to strong cash market.