Microencapsulated feed additives allow improved production efficiency in weaner pigs

Zinc oxide (ZnO) is widely used at high levels (3000 ppm) in order to control enteric disease in weaner pigs (Poulsen 1995), nevertheless, regulatory issues and the need to reduce environmental loads of zinc has resulted in lower allowable inclusion rate of zinc (Case and Carlson 2002). Industry must look at alternative methods that allow for lower inclusion levels without reducing efficacy. This study aimed to assess performance benefits offered by the inclusion in weaner diets of microencapsulated blends of ZnO, essential oils and organic acids as an alternative to high levels of ZnO, with the hypothesis that microencapsulated blends would show equivalent performance to the ‘standard’ ZnO treatment.

One hundred and forty pigs (C29 × 400, PIC, Grong Grong NSW) entered the experiment weekly (CHM PP 75/15) at weaning (21 days) and were on experiment for 28 days. Five weeks’ worth of entries were utilised in this experiment with 10 pens of pigs (n = 14) entered per week, resulting in 10 replicates per treatment. A base starter diet (14.9 MJ digestible energy (DE)/kg, 0.9 g standardised ileal digestible lysine/MJ DE) was formulated, which included 3000 ppm of bentonite. Treatments differed by part or total substitution of the bentonite with the additive, such that diets remained isoenergetic and isonitrogenous, and were Control (Ctrl) with no additive, (ZnO) containing 3000 ppm ZnO, P(ZnO) containing 1000 ppm of protected ZnO (Zinco-Plus™, Jefo Nutrition Inc., Canada), P(OA+EO) containing 1000 ppm of a protected blend of organic acids and essential oils (Porcinat+™, Jefo Nutrition Inc.) and P(ZnO)+P(OA+EO) containing combination of 1000 ppm of protected organic acids and essential oils and 1000 ppm of protected ZnO. Microencapsultaed additives were based on a fat matrix protection for controlled released of active ingredients in the gastrointestinal tract. Data were analysed by ANOVA using Genstat 18 (VSN International, Hemel Hempstead, UK) with treatment as main effect, entry week as blocking factor and entry weight as a covariate, differences between treatments were determined by l.s.d. (P < 0.05). There was a significant blocking effect related to entry week, however, there were no interactions, so only main effects are shown in Table 1.

Table 1.  Weight and growth performance of Ctrl weaner pigs compared to weaner pigs receiving ZnO, P(ZnO), P(OA+EO) or a combination of both microencapsulated products for 4 weeks

The supplementation of a combination of P(ZnO)+P(OA+EO) had a significant positive impact on growth performance of weaner pigs by comparison to the control treatment, P(ZnO)+P(OA+EO) pigs had a higher exit weight (P < 0.008) and a lower feed conversion ratio (P < 0.032). The combination of P(ZnO)+P(OA+EO) did not differ in performance to the ZnO treatment and thus appears to be a viable alternative to high levels of free ZnO.