Can sow diets enriched with extruded flaxseed replace antibiotics in starter feeds?

Saturday, October 3, 2015

With the use of in-feed antibiotics being phased out over the next three years, finding alternate strategies to help piglets cope at weaning time has taken on new importance

by L. EASTWOOD, D.A. GILLIS, M.R. DEIBERT and A.D. BEAULIEU

In order to help combat the stress/immune response at the time of weaning, piglets are often fed a diet containing a low level of antibiotics. This helps the piglets cope with any potential secondary infections which may be contracted while their immune system is vulnerable. In many markets, the use of in-feed antibiotics is banned. In April 2015, Health Canada announced that the use of in-feed antibiotics will be phased out over the next three years. Finding alternate strategies to help piglets cope at the time of weaning is important, and nutritional modulation for this purpose is a growing
area of interest.    

Flaxseed is a rich source of omega-3 fatty acids, which are known to have many different health benefits, including anti-inflammatory properties. Omega-3s can be easily transferred to piglets via the milk when sows are fed diets containing a good quality source (Eastwood, 2014). Additionally, changing the fatty acid profile of sow diets by adding omega-3 can affect the inflammatory responses of their offspring (Eastwood et al., 2012). It is possible that by improving the health of piglets prior to weaning, through nutritional modulation of the sow, we can remove antibiotics in the nursery diets. An experiment was designed to test that hypothesis when piglets were weaned at three or four weeks of age.

A total of 103 sows were used for this trial, 52 weaned at four weeks of age and 51 at three weeks. Within each weaning group, sows were fed one of two diets (control or omega-3) throughout lactation. At the time of weaning, 10 piglets from each litter were selected, moved to the nursery and housed in two groups of five piglets each (two nursery pens per litter). One half of the litter (one pen) was fed a starter diet containing antibiotics (LS20), and the other half received the same diet without antibiotics. After one week, all piglets were switched to a common phase two diet for the remainder of the study. Prior to weaning, nurseries skipped a single-wash cycle to ensure that each weaning cohort was immunologically challenged. Regardless of weaning age, all piglets completed the trial at 56 days of age.

Piglet performance was determined in both the farrowing and nursery rooms. Sow milk was collected during mid-lactation to determine the fatty acid profile. Piglet health was determined by testing complete blood count (CBC) and monitoring chemistry blood panels two days post-weaning. A total of 1,181 piglets completed the lactation portion of the trial. Of those, 1,021 piglets were used for the nursery portion.  

Feed intake was not affected during any of the other weeks on trial for these piglets. For piglets weaned at four weeks of age, ADG tended to be greater in piglets fed diets with antibiotics for week one of the trial, which also lead to improved G:F ratios during that week  Growth and G:F were unaffected by the inclusion of antibiotics from weeks two to four in the nursery. Feed intake tended to be higher in piglets fed antibiotics during week three and was significantly higher in week four relative to piglets who received no antibiotics in the first week post-weaning (930 g/d vs. 900 g/d); however, this did not impact G:F. We observed no dietary effects (sow diet or nursery diet) on the final body weight of piglets when they left the nursery. However, regardless of dietary treatment, piglets weaned at three weeks of age were about 1.5 kg heavier than those weaned at four weeks.

We found no effects of sow or phase one diet on any of the blood measures taken when piglets were weaned at three weeks of age. When piglets were weaned at four weeks of age, piglets weaned from sows fed diets containing omega-3 fatty acids had lower white blood cell counts relative to those weaned from sows fed the control diet. White cell counts were unaffected by phase one diet, and neither sow nor phase one diet affected any of the other blood parameters measured.

Regardless of diet, piglets weaned at three weeks of age had lower creatine kinase (CK), aspartate aminotransferase (AST) and white blood cell (WBC) counts relative to those weaned at four weeks. CK and AST are enzymes involved in muscle catabolism, which may be a factor in why pigs weaned at three weeks of age were heavier at the end of the trial.

To summarize, we hypothesized that feeding omega-3 fatty acids to sows in the form of flaxseed would allow for the removal of antibiotics in starter feeds. Based on the findings from this trial, we can neither accept nor reject this hypothesis as we found that, in our high-health herd, antibiotics had no benefit when fed for the first week post-weaning.

Results from this trial have clearly shown that, in a high-health situation, the use of in-feed antibiotics post-weaning had no benefit, regardless of weaning age. This experiment has also shown that, at nursery exit (eight weeks old), piglets weaned at three weeks of age had heavier body weights than those weaned at four weeks, which in part may be due to the fact that piglets weaned at three weeks had lower WBC, CK and AST counts relative to those weaned at
four weeks.

Based on the findings from this trial, when piglets are raised in a clean, high-health facility, there is no need to include antibiotics in the phase one diets post-weaning. Additionally, weaning piglets at three weeks of age may be more beneficial to the producer if they are able to produce piglets with the same nursery exit weights relative to pigs weaned at four weeks. This may vary across facilities and should be monitored closely to ensure final output is not compromised, but may be a strategy to help reduce the cost of raising pork and help improve sow longevity. BP

The authors acknowledge with gratitude project funding provided by the Saskatchewan Ministry of Agriculture and the Canada-Saskatchewan Growing Forward bi-lateral agreement, as well as the Western Grains Research Foundation. Additional project support has been provided by O&T Farms. The authors would also like to acknowledge the strategic program funding provided by Sask Pork, Alberta Pork, Ontario Pork, the Manitoba Pork Council and the Saskatchewan Agriculture Development Fund. In addition, we  also wish to acknowledge the support of the production and research technicians at Prairie Swine Centre that make it possible to conduct this research.