Abstract: The objective of this study was to explore the effects of different proportions of alfalfa meal in the diet of replacement gilts and pregnant sows on production and reproductive performance. 640 healthy gilts (Landrace×Large white) 110 days of age and 45 kg live weight were randomly divided into four treatment groups; control group (0% alfalfa meal), 5% alfalfa meal group, 10% alfalfa meal group and 15% alfalfa meal. Each treatment was replicated 4 times with 40 pigs in each replicate. The gilts offered 5% alfalfa meal had the best daily weight gain and estrus percentage. These animals were selected for on-going assessment and divided into a control group-Ⅰ(0% alfalfa meal), 10% alfalfa meal group, 15% alfalfa meal group and 20% alfalfa meal group following estrus and artificial insemination. The replacement gilts in the initial control group were retained in the control group (0% alfalfa meal) during the gestation period. There were 5 treatments with 4 replicates each treatment and 3 pigs in each replicate during pregnancy. The results showed that in replacement gilts weighing 45-70 feed intake of the alfalfa meal groups was lower than the control group, with greater reductions as alfalfa meal proportion increased. The daily gain and feed conversion rate in the 5% alfalfa meal group were significantly higher than those of 10% and 15% alfalfa meal groups (P<0.05), however, there were no differences between 5% alfalfa and control group. The weight gain cost of the 5% alfalfa meal group was lower than the control group. At 70-130 kg live weight, both feed intake and the daily gain in the three alfalfa meal groups were lower than the control group; the 10% and 15% alfalfa meal groups were significantly lower than the control group (P<0.05), declining linearly as alfalfa meal increased. The F/G (ratio of feed to gain) and the weight gain cost of the 3 alfalfa meal groups were higher than the control group, and had an increasing tendency with increasing % of alfalfa meal in the diets; the 15% alfalfa meal group was significantly higher than the control group (P<0.05). The estrus rate of gilts in the 5% alfalfa group was improved, but there were no difference among the 4 treatments. In pregnancy, the back fat thickness of the all alfalfa meal groups were significantly higher than the control group and the control group- Ⅰ(P<0.05). The live birth litter size of control group-Ⅰand the 10%, 15%, 20% alfalfa meal groups was significantly higher than that of control group, and the newborn litter weight was increased by 14.9%, 6.9%, 12.3% and 24.5% respectively, while the % of weak piglets declined by 53.44%, 36.39%, 87.37% and 62.78%, respectively. It was concluded that the growth performance of gilts fed 5% alfalfa meal was not affected but estrus rate and reproductive performance were improved. During pregnancy, live birth litter size, birth litter weight and piglets' health were greatest in the group fed 20% of alfalfa meal in the diet.

Key words: replacement gilts, pregnant sows, number born, newborn litter weight