Health y omega-3 fatty acids can benefit both the sow and her off spring. Francis Palmer explains a trial in which this was put to the test.
Over recent years research has highlighted the importance of omega-3 fatty acids in health nutrition. These are especially long-chain unsaturated fatty acids, only discovered in the 1960s with the advent of good detection techniques. Of the ten or so omega-3 fatty acids only two are of significance and they are EPA and DHA (eicosapentaenoic and docosahexaenoic) fatty acids. They are involved in cell division, structure and growth in all cells from brain to muscle. If the cell structure is weak it allows the penetration of bacteria and viruses into the cell. If there is a deficiency of EPA and DHA, the activity of muscles is reduced. In the case of fertility, as they are essential components of the spermatozoa tail muscle, needed for motility and good penetration of ova wall, fertilisation will be affected.
Pigs can not synthesise EPA and DHA and the natural sources would be grubs, worms and insects that obtain these omega-3 fatty acids from certain plants. With domestication these sources have been removed but animal products such as meat-and-bone meal, tallow and fishmeal have been good sources. These animal products have been largely derived from ruminants which stored the excess EPA and DHA – originally derived from grass - in the backfat, etc. Over recent years with the ban on the use of animal products and fishmeal in ruminant diets, and the change in feeding systems of ruminants, i.e less grass, there is less, if any EPA and DHA in the backfat and consequently the animal products contain less if any EPA and DHA meaning pig diets need to be supplemented. However, certain fish oils are good sources of EPA and DHA but tend to be expensive and very variable.
Role in fertility
Omega 3 fatty acids have an important role in pig fertility. The fertility cycle in pigs starts with the production of a wave of follicles, about 25 per wave for sows. For good piglet production all these follicles need to be strong and active. As they are cells, EPA and DHA are needed to make these cells strong and active. Once they reach a certain size they break through the ovary walls to form an ulcer, the corpus leutea. This releases progesterone that manifests itself as the sow being on heat. It is important that this secretion does not go on longer than three days, otherwise it will not allow conception to take place. So the ulcer must heal quickly and EPA and DHA facilitates this healing. After fertilisation the embryos float around in the uterus for about three weeks before implantation. During this time they have to stimulate their own food supply by making contact with the uterus wall. Failure to do this will cause them to die of starvation, hence the need for active follicles. When contact with the wall has been made it is important that the food supply is available and this is a function of the hormone oestrogen (oestradiol) that is EPA and DHA dependent. If these fatty acids are short then food supply will be short and embryos will die. In practise, the consequences of insufficient EPA and DHA are:
• Sows returning to service
• Fewer than potential piglets born
• Weak piglets
• Variable piglet weights
• Slower growth rates
• More subject to disease
• More piglet aggression
• More piglet crushing
Trials with piglets
Numerous trials have been done in research stations on these aspects but few commercial trials carried out because of the difficulty of doing accurate measurements. Ufac UK Ltd in conjunction with a commercial feed company was able to carry out such a trial in Northern Ireland to test the effects on piglets of feeding omega-3 fatty acids to lactating sows. The trial was carried out on a 780-sow commercial herd by feed company John Thompson & Sons Ltd in collaboration with the Hillsborough Agri-Food & Biosciences Institute, - formerly the Agricultural Research Institute. Omega 3 Premix for Pigs and Poultry from Ufac was added to the sow diet at 5% as a source of EPA and DHA fatty acids. Sixteen sows were allocated to treatment and control groups in two replicates. The EPA and DHA supplement was mixed into the existing diet and fed to dry sows from 60 days before farrowing and also in the lactating diet until weaning, but the creep diet was not supplemented.
The average feed intake for the lactating sows is shown in Table 1. No records were kept of sows’ feed intakes before farrowing. In the control group 10.82 piglets were born and in the trial group 10.5. The four day weight of the control piglets was 2.17 kg and the trial piglets weight was 2.27 kg. Although the extra 4.4% increase in piglet weight at four days is small, and may not be statistically significant, extra weight at this stage is hugely significant in subsequent performance.
The days to weaning were not available and creep-feed intakes were not measured. The weights at weaning were 7.86 kg for the control piglets and 8.46 kg for the trial piglets. A typical target weight at 28-day weaning is over 9 kg per piglets. The control group fell well below this but the treatment group was much closer at 8.46 kg. The difference between the two groups was 7.6% in favour of the EPA and DHA-fed pigs. Achieving good weaning weights pays dividends in greater growth potential. Literature shows EPA and DHA–fed pigs to achieve much better performance from 25 kg to finish than those not so fed. Assuming it takes 140 days from weaning to finish with the control group then an increase in growth rate of 7.6% would mean that this period is reduced to 130 days – a saving of 10 days or 10 x 2 kg of feed for maintenance. This is equivalent of 20 kg of feed. At £120 (€135) per tonne this is worth £2.40 (€2.69) per pig*. Sow performance after weaning in such trials is very important. Sow feed intake was increased and there was a reduction in days to service and more effective service. For optimum performance a sow needs to eat 6.5 kg per head per day. The control group was below this with 5.6 kg, whereas the treatment group is much closer to it at 6.2 kg. This 10% increase in feed intake must give significant responses later in terms of maintaining sow condition showing signs of heat and conception and – finally – numbers born in subsequent parities. Days to service for the control sows was 5.57 days for trial sows this was 4.45 days. Other parameters were not recorded.
From this trial it was shown that piglets from sows fed omega-3 fatty acids achieved increased four-day and 28-day weaning weights, resulting in estimated benefits of £2.40 (€2.69) per finished pig. However, it needs to be taken into account that the litter size was slightly smaller in the treatment group, which often means that the birth weight of the piglets is higher than the piglet weight in larger litters. The number of piglets born depends on the number of follicles shed before service – their vigour and strength, fertilisation and implantation. As EPA and DHA were not being fed at this period it would not be expected to make any difference. Consequently feeding EPA and DHA to sows before farrowing would have made this change in the foetus and this could be a nice angle to elaborate on this topic in future research studies.
* Prices based on time of printing
Source: Feed Mix magazine Volume 17. no. 3