The effects of long-chain polyunsaturated fatty acids (LC PUFAs) have been frequently investigated in sows because the profitability of pig production depends mainly on reproduction performance. In feeding trials, different sources and doses of n-3 PUFAs-rich feeds were used with various breeds and stages of production; however, a discrepancy in the response of n-3 PUFAs on sow reproduction has been observed. According to the results of the previous studies, n-3 fatty acids can postpone the time of parturition, decreasing the synthesis of prostaglandins, which are necessary for uterus contraction during labour. These effects could also be useful during the post-weaning period when low prostaglandin levels are indispensable for embryo survival. The n-3 fatty acids fed during the lactation period secreted in milk, may improve piglet performance. In this review, we will focus on the contradictory results of previous studies concerning practical swine nutrition. The main purpose of the review is to highlight those periods of swine breeding when the use of n-3 fatty acids may be advantageous in case of the deficiency of these essential nutrients. In finding the appropriate dose of n-3 PUFAs in terms of sow nutrition, the n-6 PUFAs levels in the given feeds must be taken into account to ensure that there are no significant reductions in the final n-6/n-3 ratio. Despite the numerous previous field trials, there are no current feeding recommendations available for PUFAs in swine nutrition. Hence, more research is required in different practical feeding situations to certify the assumptions and conclusions of this review.

The effects of n-6 and n-3 fatty acid supplementation on the fatty acid profile of sow milk were investigated using traditional fatty acid analysis and a novel method of the electronic nose (EN). The control group received 6.3 g of sunflower oil (SO) rich in n-6 fatty acids per kg feed, and experimental animals received the same amount of fish oil (FO) as an n-3 fatty acid source. The diets were corn- and soybean meal-based diets. Supplementation of SO enhanced the amount of linoleic acid (C18:2, n-6) (SO: 8.43 mg/mL vs. FO: 6.63 mg/mL milk), and significantly increased (p < 0.02) the amount of total polyunsaturated fatty acids (SO: 9.92 mg/mL vs. FO: 8.61 mg/mL milk) in the sow’s milk. On the contrary, FO significantly increased the amount of n-3 polyunsaturated fatty acids (FO: 1.17 mg/mL vs. SO: 0.69 mg/mL milk), especially eicosapentaenoic acid (C20:5, n-3), docosapentaenoic acid (C22:5, n-3), and docosahexaenoic acid (C22:6, n-3), in the milk (p < 0.001). FO and SO supplementation did not affect the analytical composition of milk. Milk samples collected from the differently fed individuals could be clearly separated according to the feeding groups based on the odour profile described by the EN.

Background: Sows are exposed to severe stress and hormonal challenges during their whole productive life. As polyunsaturated fatty acids play an important role in immune and reproductive functions, with a better understanding of their role in breeding sows’ nutrition, improved performance and more sustainable pig production can be achieved.Objectives: In this study, we investigated the effects of omega‐6 and omega‐3 fatty acid supplementation on the antioxidant status and hormone levels of sows.Methods: A total of 48 Danish Large white × Danish Landrace sows were supplemented either with sunflower oil (SO) as a control group or with fish oil (FO) as experimental group at the same dose of 10 g/kg feed. Blood samples were collected on day 14 of lactation, 5 days after weaning (insemination), and 30 days after insemination. To estimate antioxidant and reproductive effects, the amounts of reduced glutathione (GSH), thiobarbituric acid reactive substance, the activity of glutathione peroxidase (GPx), serum 17β oestradiol (E2), progesterone (P4), and 6‐keto prostaglandin F1α (6‐keto PGF1α) levels were investigated.Results: FO‐based supplementation increased GPx activity on day 14 of lactation. Five days after weaning, the concentration of GSH in FO‐fed sows was significantly higher than that in SO‐fed sows. The E2 content of blood was significantly lower in the experimental group than in the control group for two of the three examined periods (day 14 of lactation and 30 days after insemination), whereas P4 levels were significantly higher in the experimental group 5 days after weaning. We found that 6‐keto PGF1α levels were systematically lower in the experimental group throughout the trial.Conclusions: This study provides evidence of the major impact of omega‐6 and ‐3 fatty acids on the tested hormone levels, which serve as precursors for the production of E2 and P4 but have an opposite effect on PGF2α production.

This study was conducted to investigate the effects of supplemental n-6 and n-3 fatty acids on sow’s milk fatty acid composition during the lactation period and on reproductive efficiency of sows in the subsequent gestation period. Data were collected on a total of 213 DanBred sows (108 control and 105 experimental) representing parity of 2–7, respectively. Control and experimental sows were placed in the same housing conditions during lactation and gestation period. Control group received 6.3 g of sunflower oil (SO) per kg feed as n-6 fatty acid supplementation, whilst experimental animals received the same amount of fish oil (FO) as n-3 fatty acid source. Diets were corn meal-extracted soybean meal based. The experiment was conducted in one replication as being a part of a longer and more comprehensive trial. It was found that the consumed long-chain polyunsaturated fatty acids (LC-PUFAs) appeared in the sow’s milk and changed its fatty acid profile. With this alteration, the n-6/n-3 ratio of experimental (FO) sows’ milk were narrower than in SO group (SO: 13.82 vs. FO: 5.89). The benefits of n-3 fatty acids supplementation were evident for the subsequent reproduction cycle, when experimental sows heated more reliable and earlier than control (weaning to oestrus interval: SO: 5.86 vs. FO: 4.48 days). Only 2.33% of experimental sows (FO) did not heat within 7 days after weaning, but this was 12.36% in the control group (SO). The present study requires further research to evaluate the effect of n-3 fatty acids on maintenance of pregnancy and improved subsequent litter size.

Összefoglalás. A kutatás célja olyan n-3 zsírsavakra alapozott takarmányozási módszer fejlesztése, ami javíthatja a nagy teljesítményű tenyészkocák termelési mutatóit, és ezáltal gazdaságosabbá teheti termelésüket. A kifejlesztett kiegészítő takarmányok hatásainak vizsgálata nagyüzemi körülmények között, több kísérletben, különböző dózisokban és eltérő időszakokban etetve történt. Az eredmények pontosabb értékelése céljából a hagyományos vizsgálatok mellett gyorsvizsgálati módszerek (pl. elektronikus orr) alkalmazására is sor került. A kísérletek eredményei alapján olyan etetési stratégia kidolgozása van folyamatban, amely hatékonyan képes kiegészíteni a magyarországi sertés késztakarmányok esszenciális zsírsavkészletét, és hosszú távon eredményesen javíthatja a tenyészkocák teljesítménymutatóit. Summary. The research aimed to develop a feeding strategy based on n-3 fatty acids, which can improve the production parameters of high-performance breeding sows and thereby make their production more economically advanced. To earn this, the effects of the developed supplementary feeds on the performance of sows and their piglets in several large-scale swine farm experiments, at different doses and periods were investigated. In the first trial, the effects of n-6 and n-3 fatty acid supplementation on the performance parameters of sows and the fatty acid profile of sow milk were examined. Besides traditional fatty acid analysis, a novel electronic nose method was also used. The control group received 10 g of sunflower oil-based supplementation rich in n-6 fatty acids per kg feed. Experimental animals received the same amount of fish oil as an n-3 fatty acid source. The diets were corn- and soybean meal-based. Supplementation of fish oil reduced the wean to oestrus interval (non-significantly) in the trial group and decreased the number of sows having oestrus later than seven days after weaning. The treatments did not affect the performance of the subsequent farrow of sows. Supplementation of fish oil significantly increased the amount of n-3 polyunsaturated fatty acids, especially eicosapentaenoic acid (C20:5, n-3), docosapentaenoic acid (C22:5, n-3), and docosahexaenoic acid (C22:6, n-3), in the milk (p < 0.001). The chemical composition of milk was not affected by the treatments. The electronic nose could separate milk samples collected from control and trial groups based on their odour profile. In the second trial, the effects of n-3 fatty acid supplementation on the performance parameters of sows and their piglets were investigated in a special nutritional situation when α-linolenic acid (C18:3, n-3) was already high in the sows’ compound feeds. The control group received no supplementation during the trial, but experimental animals received 5 g of fish oil-based supplement instead of linseed meal-based supplementation. The diets were corn- and soybean, and linseed meal-based. Supplementation of fish oil during lactation reduced the weaning mortality of piglets in the trial groups (1st replication: p < 0.00; 2nd replication: p < 0.04). Wean to oestrus interval decreased significantly in the case of the trial group in the 1st replication (p < 0.019) but was not changed in the 2nd. The rate of late oestrus, conception, and farrowing were apparently improved in the trial group in both replications compared to the control. The results of the subsequent farrow were also better in the trial group, where the number of live-born piglets increased in both replications compared to the recent farrow. Based on the results, a feeding strategy is being developed that can effectively supply Hungarian sow feeds with those n-3 fatty acids, which can improve the long-term performance parameters of breeding sows.

Az omega-3 zsírsavak etetése jelentős hatással lehet a tenyészkocák szaporodásbiológiai teljesítményére, mivel pozitívan befolyásolják a tüszők érését, növekedését és az embriók túlélési esélyét. A szerzők által elvégzett kísérlet, valamint petefészek-vizsgálatok eredményei igazolták, hogy a szoptatás alatti 12,6 g/kg dózisú halolaj etetése, napraforgóolajjal szemben, eredményesen javította a tenyészkocák fialási teljesítményét a következő fialás során, valamint az említett fialás utáni szoptatás során etetve szintén pozitív hatást gyakorolt a kocák petefészekképleteire.