IMPROVE IRON STATUS with high doses of phytase


By Dr. Peter Wilcock and Dr. Gustavo Cordero, AB Vista


With today’s sows producing more pigs per litter, it is not uncommon to see lower average weaning weights as a consequence. Improving post-weaning pig performance is still a key focus of pig production systems and one area of interest that is worth investigating further is the iron status of piglets at weaning. Typically newly weaned piglets are injected with iron (200 mg) to


avoid iron deficiency. This is important as piglets born indoors have a low level of iron stores and do not have access to oral iron in the form of soil, while sows’ milk is low in iron. Without iron injection, pigs will become iron deficient or anaemic, characterized by an insufficient number of red blood cells, an insufficient amount of haemoglobin, loss of appetite, lethargy, increased respiration rate, poor growth and mortality.


INCIDENCE OF ANAEMIA ON COMMERCIAL FARMS With anaemia causing production losses, the iron status of piglets has received greater attention. A recent study in Canada has indicated that even with an iron injection, modern pigs from high production systems may still become borderline anaemic by weaning. This anaemia is often associated with the fastest growing or heaviest pigs at weaning. The Canadian study looked at the iron status of over 1000 piglets from 20 commercial farms. Each commercial farm had the management practice of using iron injection (200 mg) with newly weaned piglets, but even with iron injection there was still a higher percentage of piglets (≈35%) that were iron deficient or anaemic at weaning (Figure 1). Surprisingly, despite the pigs moving on to iron-supplemented feed,


Figure 1. Percent of pigs measured at weaning that were classed as anaemic, deficient, normal in relation to blood haemaglobin levels; 20 commercial farms (> 1000 piglets) Reference: Perri et al, 2016


7% 28% 28% 7% 65% 65%


the level of iron deficiency further increased to 60% at three weeks post-weaning, and this was exacerbated by higher level of zinc oxide in the diet. Furthermore, piglets that were anaemic at weaning were 0.83 kg lighter at 21 days post-weaning. This research on commercial pig farms suggests that even with


the use of iron injection, piglets are still susceptible to anaemia and poor post-weaning growth. Although generally seen as mitigating anaemia, iron injections may also have some potential negative effects associated with higher oxidative stress on the animal. Indeed, studies have indicated that the requirement for biological antioxidants increases in piglets that have had an iron injection.


SHIFT IN DIETARY PROTEIN SOURCES CONTRIBUTING TO PROBLEM One area of consideration that may impact iron status of piglets is the change in starter feed diets over the last few years. Traditionally, piglet diets consisted of high digestible animal proteins such as fishmeal and in certain markets plasma protein which relative to vegetable based proteins contain higher levels of iron. However more recently with a focus on lower cost diets, coupled with a greater understanding of raw materials and digestible amino acid requirements of the piglet, a greater emphasis on vegetable-based proteins has resulted. With increasing vegetable proteins such as soybean meal, soy protein concentrates and cereal by products replacing animal proteins, the result is starter feed diets that are lower in dietary iron. Even with iron supplementation (100 to 200 ppm from iron sulphate), the higher phytate levels associated with the high vegetable protein content results in a high phytate:iron ratio. Phytate is a strong chelator of divalent metal ions such as iron and so this dietary change, of increased dietary phytate and lower dietary iron, results in both lower levels and poor bioavailability of dietary iron. With marginal iron status on commercial farms, this trend towards higher vegetable proteins and phytate levels in starter feeds may potentially be a contributing factor to higher incidence of anaemia seen on farms today.


Normal (Hb >11 g/dl) Normal (Hb >11 g/dl) Deficient (Hb > 9 g/dl < 11 g/dl Deficient (Hb > 9 g/dl < 11 g/dl PAGE 28 MARCH/APRIL 2018 FEED COMPOUNDER Anemic ( < 9 g/dl) Anemic ( < 9 g/dl)


HIGH DOSES OF PHYTASE TO UNLOCK THE DIETARY IRON POTENTIAL BOUND BY PHYTATE Traditionally 500 FTU/kg phytase has not been used in starter feeds (wean to 21d) for phosphorus release due to the lower levels of dietary phytate associated with animal protein based feeds and the high use of zinc oxide. However, with dietary phytate well recognised as an anti-nutrient, the use of high doses of phytase in starter feeds to target >80% phytate destruction has resulting in improved post-weaning


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