Plant based mixtures, when chosen properly, have a positive effect on feed intake and consequently growth performance in weaning pigs. They contribute to nutrient digestibility resulting in fewer light weight piglets and more full-value pigs at slaughter.
By Karola Wendler and Gina Medina, Delacon, Austria
Piglet weaning is very challenging and probably one of the most critical stages in pig production. Depending on weaning age, commonly at 21 and 28 days or even earlier, piglets are physiologically and immunologically immature. The separation from the sow, presence of pathogens as well as environmental and dietary changes are some of the stressors that affect piglet health and nutritional condition. They lead to a low and variable feed and water intake during the first few days after weaning. Consequently, piglets experience diarrhoea, dehydration, weight loss, lower immune function and poor growth performance.
Main considerations in diet formulation based on the biology of young pigs include the animals’ high level of body protein deposition, reduced feed intake, developing immune system, variable level and activities of digestive enzymes at birth, and limited ability in dietary fat utilisation. Studies showed that optimised feed intake in nursery increases growth rates, reduces enteric disease incidence and positively affects growing and finishing stage performance.
Indeed, feed intake is critical in the post-weaning period. Feed refusal has negative effects on gut morphology and function. Known problems in early weaned pigs are villous atrophy and crypt hyperplasia, reducing brush-border enzymes and, thus, impairing nutrient break-down and absorption. Hence, appropriate nutrition and management strategies must be applied.
Phytogenic Feed Additives
Apart from the rising feed and production costs in pig production, the negative effects of using antibiotic growth promoters in feed lead to continuous evaluation of functional feed additives. These natural growth promoters achieve high feed efficiency and maximise pig performance as well as productivity. Phytogenic feed additives (PFA) are plant-based products of individual or mixtures of essential oils, herbs, spices and/or extracts thereof. Commercial phytogenic products vary in their composition but many contain essential oils as main active ingredients. Due to their strong aromatic properties, carefully selected and standardised essential oils can positively affect feed intake in pigs. Furthermore, certain essential oils exert secretolytic and spasmolytic properties, which are known for caraway and fennel oil. In traditional medicine these plant-derived oils are used for the treatment of digestive disorders. The increase in gastric juice, bile secretion and/or activity of digestive enzymes by essential oils and pungent substances facilitates the nutrient uptake in the gut. Therefore, PFA might be a good and effective natural feed additive to include in piglets diet in order to overcome dysfunction of digestion and finally improve growth performance.
Positive effects in piglet confirmed by EFSA
Positive effects of a standardised PFA, with essential oils of carvone and lemon as main active ingredients, on performance in weaning pigs have recently been confirmed by a positive opinion from the European Food Safety Authority (EFSA). A meta-analysis of five consecutive trials performed under field conditions with a total of more than 1000 piglets revealed a significant improvement in daily weight gain by 11% and 5% in pre-starter and starter period, respectively, increasing the final body weight by 4%. Also the feed efficiency in prestarter phase was significantly improved (+ 12%). This positive effects can be explained by the improvement in nutrient digestion, which was demonstrated for dietary nitrogen (+2.5%) and for dry matter (+2.0%) digestibility in another piglet study.
The same PFA product was evaluated in nursery diets and reported to have similar positive effects in starter pigs. In this study it was obvious that small piglets gained the most from this PFA. The number of piglets in the lowest weight category at the end of the starter phase was reduced by 39%. This may lead to a more uniform growth and, thus, to a high number of full-value pigs (fewer discounted pigs at slaughter).
Better sow productivity and reproductive performance
It is well accepted that birth weight is decisive for later growth performance in fattening pigs. Successful breeding for increased litter size in hyperprolific sows, however, has led to reduced birth weight of piglets. Findings show a decline in average birth weight of about 40g for every additional piglet born. Lightweight piglets may be removed directly after birth for viability reasons. If kept in the system, these piglets may lower profitability of pig production due to retarded growth and longer fattening period which in turn increase total feed consumption and impair feed efficiency. Therefore, improvement in performance of lightweight piglets seems crucial for increasing the number of fullvalue- pigs brought to the market. There is strong evidence that nutrient availability is a limiting factor for preweaning growth rate, especially in large litters. Hence, improving sow milk production is vital in birth-to-weaning weight gain in piglets. Feed intake in sows, however, is limited and increased milk production often comes from increased tissue mobilisation. High weight loss in sows does negatively affect reproductive performance, i.e. longer return to estrus intervals and later litter quality. Therefore, strategies to increase nutrient supply in sows are of great importance for milk yield, litter quality and reproductive performance.
Key benefits: Performance and profitability
More reasons to prove the positive effects of the PFA in suckling pigs were demonstrated in two recent scientific trials with a total of 90 lactation sows. Total nutrient digestibility of protein and dry matter was improved (Figure 1), setting the basis for high milk production and increased milk solids, respectively (Figure 2). The higher nutrient supply from sow milk was reflected in higher birth-to-weaning weight gain and higher weaning weights compared to the sows fed without PFA (Figure 3). Furthermore, piglet uniformity (100- CV) was numerically improved by the application of the PFA (90.8% vs. 87.6%). Plotting histograms of piglet’s weights at weaning showed that especially the number of piglets with low bodyweight was reduced (Figure 4B). Such an effect has already been observed at birth (Figure 4A). It can be assumed that better nutrient supply in late gestation improved pre-natal growth of piglets, as parity (2.84 vs. 2.84) or bodyweight of sows (249 vs. 248 kg, day 112 of gestation) were similar in both groups.
These results as well as those of many other scientific and field trials clearly demonstrate the positive and beneficial effects of the tested PFA product on piglet and sow performance. Phytogenic feed additives combine benefits, such as secured feed intake, antioxidant and anti-inflammatory properties and improved gut function for better nutrient digestion and absorption, which contribute to efficient and profitable pig production.