Alternatives to zinc oxide By Niels J Kjeldsen, Senior Specialist, PhD Animal Science, SEGES, Danish Pig Research Centre
Introduction For decades, pig producers in Denmark and abroad have used 2,500 ppm zinc (as zinc oxide) in piglet feed the first 14 days post-weaning as an efficient way to control post-weaning diarrhoea. As of 2004, the use of zinc oxide as a medicinal product required a prescription issued by the herd veterinarian. Records show an annual use of zinc oxide in Danish piglet production of roughly 400 tonnes of zinc in recent years. Most of the zinc used in Denmark is not deposited in the pigs;
approx. 95% ends up in the soil via pig slurry and consequently zinc concentrations in Danish soil are increasing. In 2017, the EU decided to terminate the use of medicinal zinc in pig feed by June 2022, primarily due to environmental considerations, but also due to indications that zinc may play a part in antibiotic resistance to, for instance, MRSA. Danish authorities are currently monitoring the development of alternatives to zinc oxide and are prepared to ban zinc oxide before the 2022 deadline if reliable, cost-effective alternatives become available. SEGES Danish Pig Research Centre has therefore drawn up an
action plan with two purposes: to increase research and development efforts and to strengthen the implementation of existing knowledge in Danish pig production. Several feed-based solutions have been tested on SEGES Danish
Pig Research Centre’s trial station and on commercial farms. Below, two recently completed trials are described.
Individual products as alternatives to zinc oxide The aim of this trial was partly to study the effect of 1,500 ppm vs 2,500 ppm zinc (as zinc oxide) and partly to test the effect of three additives: seaweed (Ocean Feed), probiotic (MiyaGold) and GærPlus (blend of probiotic and yeast). The test comprised six groups with 60 replicates totalling 4,200 pigs from weaning at 7 kg until 30 kg. All trial groups were compared with a diet without zinc oxide. All three additives generated significantly lower productivity in the
7-9 kg period and the 7-30 kg period com-pared with the two zinc oxide groups (2,500 ppm and 1,500 ppm zinc) and did not differ from the group with no zinc oxide. Results revealed a markedly higher frequency of diarrhoea among the pigs given the three additives compared with the pigs given 2,500 ppm and 1,500 ppm zinc. There were no differences in productivity and treatments for diarrhoea between the pigs given 2,500 ppm zinc and 1,500 ppm zinc [1]. The outcome of this test confirmed the outcome of multiple trials: replacing zinc oxide with one additive does not generate the same level of productivity and low diarrhoea frequency as feed with zinc oxide, ie. it is hardly possible to find a single ’silver bullet’ to replace zinc oxide. The test also established that 1,500 ppm zinc is as effective as 2,500 ppm zinc. In Denmark, the advisory system and Danish veterinarians are cooperating to implement 1,500 ppm zinc as standard for weaned piglets.
PAGE 42 JANUARY/FEBRUARY 2019 FEED COMPOUNDER
Feeding concepts as alternatives to zinc oxide Recognizing that individual additives are unlikely to be the answer, SEGES Danish Pig Research Centre ran a concept test in which international players were encouraged to participate. Twenty-three commercial companies applied of which four were selected for the trial: FraMelco (the Netherlands), Trouw Nutrition (the Netherlands), Evonik (Germany), and Vitfoss (Denmark). The concept test comprised six groups with 63 replicates totalling roughly 4,200 pigs in the 7-30 kg period. The four commercial concepts were compared with a positive control group (2,500 ppm zinc the first 14 days post-weaning) and with a negative control group (0 ppm zinc). Results showed that the negative control group (0 ppm zinc) and the four concepts generated a significantly lower productivity in the 7-9 kg period compared with the positive control group (2,500 ppm zinc). Only the pigs given the concept from Trouw Nutrition showed a significantly better productivity than the negative control group. In the entire 7-30 kg period, the concepts from FraMelco and Evonik were level with the negative control. The concept from Vitfoss was level with the positive control group, and the concept from Trouw Nutrition was significantly better than the positive control in terms of productivity. Results showed significantly fewer diarrhoea outbreaks among
the pigs given 2,500 ppm zinc than the pigs given 0 ppm zinc and the concepts from FraMelco and Evonik, while the pigs given the concept from Vitfoss were level with the pigs given 2,500 ppm zinc. There was a significantly lower rate of diarrhoea treatments among the pigs given the concept from Trouw Nutrition compared with the pigs given 2,500 ppm zinc [2]. FraMelco’s concept exclusively consisted of monoglycerides and organic acids, whereas the other three concepts were more complex: they all contained less protein than normal, revised amino acid profiles (com-pared with Danish recommendations), probiotics, organic acids, special fibre, enzymes and various other additives. The aim of the trial was not to determine which subcomponents affected productivity and gut health, but results revealed that two concepts performed better than 2,500 ppm zinc and two were level with the negative control group. Thus, this test confirmed once again that it is not possible to
replace zinc oxide by one additive only. Even though two concepts demonstrated promising results, the positive effect on productivity was not enough to pay for the increased feed costs. This shows that there is still a long way to go before cost-effective solutions are available. Trouw Nutrition’s concept consisted, among other things, of a
low protein content (approx. 1 percentage unit lower than the control feed), raised threonine/lysine balance, low calcium content, and organic acids, which are all known to have an impact on diarrhoea. Below, some of these factors are discussed in detail.
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