Low protein diets without medicinal zinc oxide for weaned pigs reduced diarrhea treatments and average daily gain.

The use of medicinal zinc oxide (ZnO) in post-weaning diets must be phased out in the European Union by 2022, resulting in urgent needs for alternative strategies to prevent diarrhea in pigs. The objective of this study was to test the effect of four different dietary protein strategies with different amino acid profiles on diarrhea frequency and pig performance as alternative diet plans when medicinal ZnO was will be excluded from the diet. A total of 6 800 Duroc x (Danish Landrace x Yorkshire) pigs, weaned around 28 days of age, were randomly assigned by sex and size to six dietary treatments. The treatments were; standard CP levels (191, 184, 184 g/kg CP) and allocated 2 500 ppm ZnO in phase 1 (PC = positive control), standard CP levels (191, 184, 184 g/kg CP) and no added ZnO in phase 1 (NC = negative control), CP levels of 166, 184, 184 g/kg (LSS = low-standard-standard), CP levels of 166, 162, 192 g/kg (LLH = low-low-high), CP levels of 140, 193, 192 g/kg (VHH = very low-high-high), and lastly 140, 174, 192 g/kg CP levels (VMH = very low-medium-high). The pigs entered the trial at ~7 kg BW and exited at ~30 kg BW. As expected, the PC treatment resulted in 42% fewer diarrhea pen treatments in the total trial period compared to the NC group (P < 0.05), whereas both PC and LLH had fewer diarrhea treatment days per pig compared to NC pigs (P < 0.05). Additionally, at the point of treatment, the NC pens had 33% fecal floor samples positive for pathogens, compared to 80% samples positive for pathogens in the PC pens. This suggests that ZnO has a particular positive effect on non-infectious diarrhea without bacterial involvement. A reduction in dietary CP levels in phase 1 led to a reduced average daily gain (ADG) in LLH and VMH pigs and a poorer feed conversion ratio (FCR) in VHH pigs during the overall study period compared to the NC pigs (P < 0.05). Conclusively, a diet with low CP levels from weaning to about 15 kg BW had a reducing effect on diarrhea, but decreased ADG without affecting the FCR.

Effects of alternative feed additives to medicinal zinc oxide on productivity, diarrhoea incidence and gut development in weaned piglets.

The use of medicinal zinc oxide (ZnO) must be phased out by 2022, thus prompting an urgent need for alternative strategies to prevent diarrhoea in weaner piglets. The objectives of this study were to assess the impact on weaner piglet performance, diarrhoea incidence and gut development, when (1) dietary ZnO supplementation was substituted by alternative commercial products based on macroalgae, specific probiotics or synbiotics, or (2) dietary ZnO inclusion was reduced from 2500 to 1500 ppm. A total of 4680 DLY piglets (DanBred, Herlev, Denmark), weaned around 35 days of age, were randomly assigned according to sex and BW to six different dietary treatment groups. A basal diet was supplemented with no ZnO (NC = negative control), 2500 ppm ZnO (PC = positive control), 1500 ppm ZnO (RDZ = reduced dose of ZnO) or commercial macroalgae (OceanFeed™ Swine = OFS), probiotic Miya-Gold or synbiotic GærPlus products. The piglets entered and exited the weaner unit at ~7.0 and 30 kg BW, respectively. In-feed ZnO was provided the first 10 days post-weaning, while the alternative supplements were fed throughout the weaner period. As expected, the average daily feed intake, average daily weight gain (ADG), feed conversion ratio (FCR) and diarrhoea incidence were improved in the PC compared to NC group (P < 0.05) during phase 1 consistent with improved indices of villi development observed in subgroups of piglets sacrificed 11 days post-weaning. Reduction of ZnO to 1500 ppm lowered ADG (P < 0.05) and slightly increased incidence of diarrhoea during the first 10 days after weaning (but not later) without affecting FCR. None of the three alternative dietary additives, including a 10-fold increased dose of GærPlus than recommended, improved piglet performance, gut health and gut development above that of NC piglets. The OFS piglets sacrificed 11 days after weaning had significantly lower weights of hindgut tissue and contents compared to the PC group, consistent with antimicrobial activity of the product, which was detected from anaerobic in vitro fermentation. In conclusion, dietary ZnO supplementation during the first 10 days post-weaning may be reduced from 2500 to 1500 ppm without major negative implications for weaner piglet performance and health in herds under a high management level. However, none of the alternative dietary supplements were able to improve piglet performance or gut health, when ZnO was omitted from the diet.