THE EFFECT OF VARIOUS DIET NUTRIENT DENSITIES AND ELECTROLYTE BALANCES ON SOW AND LITTER PERFORMANCE DURING 2 SEASONS OF THE YEAR

An experiment involving 289 farrowings during a 2-yr period was conduc ted to determine the effect of increasing dietary nutrient concentrati on; electrolyte balance, and season of the year on the lactational per formance of sows. Experimental diets were corn-soybean meal-based. The basal diet was formulated to meet or exceed the NRC requirements and the high-nutrient diet was formulated to contain approximately 20% hig her levels of the nutrients than the basal diet, with or without adjus tment of the electrolyte balance (Na+K-Cl) to 250 mEq/kg. Experimental diets were fed in both the warm (May through October) and cool (Novem ber through April) seasons of the year, resulting in a 2 x 2 x 2 facto rial arrangement of treatments. There were no season x treatment inter actions for any of the indices measured. During the first 21 d of lact ation, sows farrowing in the cool season consumed more feed(P < .001) and produced heavier (P < .001) pig weights and litter weight gains th an sows farrowing in the warm season. Increasing nutrient density from 100 to 120% of the NRC requirements resulted in decreased (P < .05) d aily feed consumption, but it increased (P < .001) daily CP and GE int ake, 21-d pig weights, and litter weight gains. Adjusting the dietary electrolyte balance from normal (130 mEq/kg) to 250 mEq/kg tended to i ncrease (P < .07) 21-d pig weights, but it had no effect on other indi ces measured. These data indicate that under the environmental and man agement conditions of this experiment, the nutrient requirements of th e lactating sow are higher than the current NRC standards.