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Nutritional Additives
Thursday, June 15, 2017 7:05:12 PM
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Alternatives to zinc oxide for more potent piglets


Elisabet Rodriguez, Swine Marketing Manager, Novus International, Inc.



In intensive pig production, weaning is a challenging, stressful experience for young piglets. They have to cope with an abrupt separation from their mother, being mixed with other litters in a new environment, and have to switch from highly digestible liquid milk to a less digestible, solid creep feed.  These nutritional and environmental changes contribute to gastro-intestinal and immune system disturbances, resulting in an increased susceptibility to gut disorders and, in some instances, to diarrhea, morbidity and even death. In particular, during the first week after weaning, often a reduced feed intake is seen due to a rise in blood cortisol levels as consequence of the different stressors the piglets are exposed to. This impairs growth performance and can lead to higher mortality rates, causing significant economic losses for the pig producer.

In order to manage this transition period and avoid poorer production results, often antibiotics and/or high levels of zinc oxide (ZnO) are added into the piglet’s diet. It has been demonstrated that including 2,000 to 3,000ppm of ZnO in the diet during two weeks after weaning can help to reduce diarrhea occurrence and support piglet growth. However, high dietary Zn treatment can drastically alter the bacterial composition and development of certain microbiota in weaned piglets. Starke et al. demonstrated in 2014 that adding 2500ppm of ZnO strongly decreases the number of lactobacilli, increases the number of Clostridium Spp. and stabilizes the E. coli population, rather than reducing it, in the intestines. Today, many negative side-effects of applying high doses of ZnO have been identified, such as increase of antibiotic resistance1, development of multi-resistant E. coli strains2, reduced absorption of other minerals3, decreased activity of phytase enzyme4, and negative environmental impact5 (Zn has a low bioavailability. Only two percent is absorbed, leaving the remainder to be excreted in the manure6). To minimize the risk of environmental pollution, in 2003, European regulations reduced the maximum Zn concentration authorized in pig diets (150mg Zn per kg of complete animal feed). Next to ZnO at high inclusion rates, dietary antibiotics, although today in the EU are only applicable under vet prescription and for metaphylactic use, are often also applied in piglet diets to support their post-weaning gut health and performance. However, the increased (worldwide) public concern of antimicrobial resistance has created a strong pressure to reduce the use of antibiotics in livestock production, leading to stricter rules on the exact application of certain antimicrobials and even national requirements in several EU countries. Consequently, the industry is seeking suitable, nutritional solutions to fit into their piglet gut health program, aiming to improve piglet health and productivity gradually without the use of antibiotics.

In pig nutrition, benzoic acid has been shown to increase daily weight gain and to improve feed/gain ratio in a wide number of studies. Benzoic acid has strong antimicrobial properties, and is authorized since 2007 in the EU to enhance piglet growth in feed of weaned piglets at a dietary inclusion rate of 0.5 to 1.0 percent. A unique, protected source of flavoring compounds including benzoic acid (PBA, PROVENIA™ from Novus International) aims to enhance piglet intestinal health while minimizing all negative handling aspects at the feed production site that are linked to using free benzoic acid. It’s sophisticated manufacturing technology, homogenously embedding the benzoic acid into a vegetable fat matrix, results in uniform granules for optimal intake by the piglet and ensures protection of the active ingredients throughout the stomach until they reach the intestinal tract. Here, due to the digestive enzymes, the active substances will gradually be released until the hindgut where benzoic acid exhibits an optimal antimicrobial efficacy on the gut microbiota.

A comparative trial conducted at a swine research farm in Segovia, Spain, in cooperation with Pig Champ Pro Europa, clearly demonstrated that supplementing the diet of weaned piglets with a protected in-feed solution based on benzoic acid, may be a potential alternative program to a 2-week high level of ZnO inclusion in the diet. Subsequently, PBA can be a suitable, economical alternative to ZnO, offering a more secure solution with the same benefit on piglet gut health and performance.

The performance of piglets fed a standard diet based on corn, soybean meal, without antibiotics or any specific gut health solution (Control group), was compared with that of a group offered the same basal diet supplemented with 0.25 percent PBA for 35 days (PBA group) or 3000ppm of ZnO for 14 days (ZnO group) under commercial conditions (Figure 1). Piglets were weaned at 28 days of age and distributed to the three experimental treatments. Each treatment had 72 piglets (12 pens of 6 piglets). Feed intake, average daily weight gain (ADG) and feed conversion ratio (FCR) were measured at day 0 (28 days of age), day 14 (42 days of age) and day 35 (63 days of age) after weaning.

Figure 1:  Scheme of trial set-up


After the first 14 days, piglets fed the ZnO showed numerically higher ADG versus the piglets of both other groups. However, during the 3 weeks after, when the ZnO application stopped, the ADG for the piglets supplemented with the PBA became significantly higher (9 percent vs ZnO, p=0.029). For the total period, the PBA-fed piglets achieved the highest ADG, +24g/piglet/day extra, that is +6.1 percent vs. the ZnO group (Figure 2). On FCR, the first 14 days didn’t show any difference between the treatment groups. From day 14 after weaning until day 35, the PBA-fed piglets achieved an improved feed efficiency compared to the control and ZnO-fed pigs. In this period, a 10 point decrease in FCR was seen between PBA-fed and ZnO-fed piglets (down from 1.46 to 1.36, p=0.004). For the total period (Figure 3), the PBA-fed piglets showed the best FCR (1.35 vs 1.44 compared to the ZnO-fed piglets, p<0.05).

Figure 2.  Improvement of PBA vs. ZnO on ADG of piglets 35 days after weaning


Figure 3.  Improvement of PBA vs. ZnOon FCR of piglets 35 days after weaning 


In addition, piglets fed PBA in the diet had more uniform bodyweights compared to non-supplemented or ZnO-fed piglets (Fig. 4). Mortality of piglets was not affected by the dietary treatments. No significant differences were noticed on diarrhea score or on additional therapeutic medication costs.

Figure 4.  Improvement of PBA vs ZnO on piglet uniformity 35 days after weaning 


In conclusion, this research clearly demonstrated that supplementing the diet of weaned piglets with a protected in-feed solution based on benzoic acid, may be a potential alternative program to a two-week high level of ZnO inclusion in the diet.  This could possibly be explained by PBA acting in the digestive tract to balance the intestinal microbiota and enhance digestive function in young pigs, leading to an improved utilization of dietary nutrients and better performance, with fewer digestive problems like diarrhea. This ensures an optimal piglet performance for maintaining high profitability while improving the environmental footprint of pig production in comparison to high levels of dietary Zn.



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Article made possible through the contribution of Elisabet Rodriguez and Novus International, Inc.

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