| In livestock production, voluntary feed intake during lactation of of a sow is often not sufficient to meet nutrient demands for maintenance, milk production and body growth(for gilts). A low feed intake during lactation is often a cause of a bigger weight loss and a bigger backfat loss, even a bad effect on their reproductive performance, including a prolonged weaning to oestrus(WEI), a reduced ovulation rate and pregnancy rate, a higher embryonic mortality, these consequences is bad for the economic of a pig farm. In addition to nutritional factors, poor environment, poor feeding and management also make the sow to suffer a oxidative stress. Oxidative stress has become one of the factors that limiting the reproductive performance of sows. Oregano essential oil(OEO) has very strong antioxidant capacity, it can enhance the body immunity, promote animals to eat more. A appropriate use of OEO is expected to inhance the feed intake during lactation period of a sow and alleviate oxidative stress, improve her reproductive performance. But the accurate mechanism of the OEO to improve the reproductive performance of a sow is still not clear.The current expriment is conducted to explore the changes of the feed intake during lactation of a sow, the antibodies in blood and milk, the composition of the milk and colostrum, the piglets’ growth performance, the redox state during the reproductive cycle and insulin sensitivity after a supplement of OEO in the sow’ diet. We attempt to measure the whole changes of the reproductive performance after a sow consumed OEO, and to explore the the possible mechanisms. 80 large white sows with average parity 4 were randomly divided into 2 groups, each group with 40 sows. Among them, the control group was fed a basal diet, the experimental group was feed with basic diet added with 15 g/t OEO, for a trial period of breeding sows and weaned. During the test, the sows colostrum and milk and blood samples were analyzed. The results are as follows:1. The effects of OEO on sow’ weight and backfat, WEI, farrowing performance, and the average daily feed intake during lactation:(1) Compared with the control group, the weight at mating, at 107 d of pregnancy, at perturition, at weaning and the weight gain during gestation were not significantly changed(P > 0.05); lactation weight loss decresed(10.3±9.5kg vs 12.6±11.9kg), but the difference was not significant(P>0.05). Similaly, the backfat at mating, at 107 d of pregnancy, at perturition, at weaning, the backfat deposition during gestation and the backfat loss during lactation were not significantly changed(P>0.05). The WEI in OEO group decresed(4.63±0.77 d vs 4.9±0.69d), but the difference was not significant(P>0.05).(2) Compared with the control group, the total born and abnormal born were not significantly changed(P>0.05); the number born alive, birth weight, birth litter weight increased, the stillbirth and birth process decreased, but did not reach significant levels(P>0.05).(3)During pregnancy, the sows received almost the same quantity of feed(2.42±0.03 kg vs 2.43±0.02kg) Compared with the control group, although the feed intake of the first week and second week did not increased(P > 0.05), the feed intake of the third week increased significantly(6.00±0.78 kg vs 6.46±0.82kg)(P<0.05).2. The effects of OEO on the performance of piglets: while the number of weaned piglets and the breeding rate, sows with piglets, the 7d weight and 14 d weight of piglet, 7d litter weight, 14 d litter weight, 21 d litter weight, the average daily gain in the first week and second week, the litter weight gain of the first week and second week, 1-21 d average litter weight gain did not change significant(P>0.05); but the 21 d piglet weight(P=0.05), 1-21 d piglet average daily gain(P=0.05), the litter weight in the third week(P<0.05) change significantly; the average daily gain of the third week extremely omproved(P=0.01). These results indicate OEO can significantly promote the growth of the suckling piglets.3. The effects of OEO on the antibodies in blood and milk, and the ingredients of milk and colostrum: Ig G and Ig M content in maternal serum and colostrum did not change significant(P>0.05). The ingredients in colostrum and milk, such as milk fat, milk protein, lactose and total dry matter did not change significant(P>0.05).Therefore, OEO did not inhance the immunioty of the sow and the colostrum, OEO did not chaange the ingredients in colostrum or milk.4. The effects of OEO on the reproductive cycle of oxidative stress: Overview the entire reproductive cycle, oxygen free radical(reactive oxygen species, ROS), thiobarbituric acid reactive substances(thiobarbituric acid reactive substances, TBARS) in sows’ blood had increased at first and then decreased, respectively, on the parturition, or on the 109 d of pregnancy and on the parturition, they were significantly higher than other stage(P<0.05); 8-hydroxy deoxyguanosine(8-hydroxy-2’-deoxyguanosine, 8-OHd G) on the 10 d of pregnancy was minimum, the other stages were significantly higher than it(P<0.05); glutathione peroxidase(Glutathione peroxidase, GSH-Px) on the parturition compared to other phase was decreased, but the differences were not significant(P>0.05). Throughout the reproductive cycle, dietary supplementation of OEO had no significant effect on ROS levels in sows’ blood(P>0.05), but the TBARS on the parturition was significantly lower(P<0.05); on the 60d(P=0.08) in gestatin and on the parturition(P=0.07) day, the GSH-Px had an increasing trend; on the 109d(P=0.09) of pregnancy and on the parturition(P=0.06), the 8-OHd G had an decresing trend. These results indicate OEO can inhance the activities of antioxidase activity, reduce the degree of lipid peroxidation, reduce the attack of oxygen on DNA, alleviate the oxidative stress during late pregancy in sows.5. The effects of OEO on the insulin sensitivity in the reproductive cycle of the sow: On 10 d in pregnant, 3d and 7d in lactation, HOMA-IR and HOME-IS were not significantly affected by OEO(P>0.05). On 109 d in pregnant, HOMA-IR of the OEO group was lower(P=0.07) and HOMA-IS was significantly higher(P=0.035). The results indicate that, OEO improved insulin sensitivity in late pregnant sows, this may be one reason why OEO can improve the feed intake of sows during lactation period.In summary, dietary supplementation of OEO enhanced the antioxidant capacity of the late pregnant sows in a certain extent, alleviate the oxidative stress of sows, sows are conducive to maintaining good health; improved insulin sensitivity in late pregnant sows, this may increases feed intake of sows during lactation period, a increased feed intake during lactation period was supposed to promote the growth of the suckling piglets. |
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