| The effect of nutrition level during gestation on reproductive performance of primiparous sow was evaluated using 21 (LandreceX Meishan) gilts, allocated to four dietary treatments in single factorial arrangement. Treatments consisted of four nutrition levels (high, NRC, mid, low) during gestation, providing approximately 2, 1.2, 1, 0.6 times the requirement of maintenance during early gestation, increasing 20% on the base of prophase during mid pregnancy, and increasing 25% on the base of metaphase during late pregnancy. Diets provided similar amounts of miner, vitamin and fiber to all gilts. During gestation, all the experimental sows were raised in automatically weighted cages, weighted 7:00 in everyday morning. Metabolism experimentations were conducted during four 6-d periods at 3, 30, 85, 105 d of gestation; milk yield of lactating sows were measured during 1, 3, 7, 14, 21 and 28 d of lactation.The results showed:1. Supplying different nutrition levels to sows during gestation, affected pregnant weight gain obviously. As dietary nutrition increased during gestation, sows gained more. Early BW gained 4.3kg and mid BW gained 20.3kg, improved litter size and weight of individual piglet born. Enhancing late BW gain, increased litter size and weight of individual piglet born. Nutrition distribution during pregnancy: 0.5873g nitrogen/BW0.75/d and 0.1181 Meal DE /BW0.75/d during early pregnancy, 0.8295g nitrogen/BW0.75/d and 0.0884 Meal DE/BW0.75/d during mid pregnancy.2. Nutrition levels of sows during gestation, influenced litter size. Sows intaked low nutrition level diet(0.91g nitrogen/ BW075/d and 0.13Mcal DE/BW?S/d), enhanced litter size, decreased number born alive, weight of piglet born, weaning survive rate and subsequent productive performance. Number born of NRC and mid level were 3.34 and 0.67 piglets more than high level(1.82g nitrogen/ BW?5/d and 0.27Mcal DE/BW075/d). Increasing nutritionlevel during pregnancy, increased weight of individual piglet born and piglet productive performance, decreased sow feed intake and milk yield at first three days during lactating.3. Nutrition levels of sows during gestation affected milk yield of sows. Milk yield of sows in mid level was higher, in addition, milk yield of sow increased as nutrition level increased during gestation. Relation between milk yield of high level and number of days during lactating was cubic; as lactating extended, milk yield of sow in NRC and mid level increased; milk yield of low level reached highest at 24th day during lactating.4. In different levels, correlation between sow weight during late pregnancy and body length, body side length, circumference, perimeter of abdomen and hip width was positive. But body length, body side length and hip width were used to estimate sow weight, their credibility were low. So, using circumference and perimeter of abdomen, estimated sow weight, regression equation: weight = 0.0045x2 + 0.7888x - 22.902 (R2 = 0.425, P=0.000 x-circumference), weight = 0.0136x2 - 2.0698x + 149.818 (R2 = 0.504, P = 0.000 x- perimeter abdomen).5. Correlation of sow weight and backfat thickness was not significant (P>0.05), but correlation of gestation BW gain and backfat thickness was significantly positive. Pregnant BW gained 4.3kg during early pregnancy, their backfat thickness were 22mm; Pregnant BW gained 20.3kg during min pregnancy, their backfat thickness were 21mm; but correlation of pregnant BW gain and backfat thickness during late pregnancy was not significant.6. The rule of sow excreting feces and urine: High nutrition level contrast to other levels, color of its feces was lighter and more watery. Feces color in low nutrition level was deeper and dryer than other nutrition levels, frequency of excreting feces and urine increased, excretory quantity was little. Time of sow lying in high level was longer than other levels, but time of sow standing was longer than other levels. Sows in low nutrition level showed stereotyped behavior, such as frequency of drinking water increased, em...
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