Evaluation of Yucca schidigera extract inclusion in fattening pig nutrition: impact on performances, nitrogen use and slurry composition

This study aimed to evaluate the effects of a Yucca schidigera extract (YSE, 10.8% saponin richness) on the performances, nitrogen balance and environmental impact of fattening lean pigs. For it, a total of 40 Pietrain x (Landrace x Large White) pigs, with 76.1 ± 5.2 kg of mean body weight (BW), 50% boars and 50% gilts, were involved in a trial that lasted 42 days. The parameters evaluated were: growth performances, farm nitrogen (N) mass balances, fecal and slurry composition and carcass and meat quality. Animals were allocated in 20 pens (two pigs each one). There were four treatments in a factorial design 2 x 2, with two sexes (boars and gilts) and two diets (0 and 300 mg/kg of YSE). The dietary treatment did not influence the average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) and neither affected the characteristics of carcass (yield, lean content, backfat thickness) or meat (color and marbling, chemical composition and texture). Also, the administration of YSE produced no impact on the estimated N excretion, fecal ammonia (NH3-N) content or total volatile fatty acid (VFA) content and VFA profile of the feces. Nevertheless, even not statistically significant, it is worth to note that the YSE inclusion in pigs’ diet carried out a reduction in the total N (-21.5%) and in the NH3-N ( 27.8%) content in the slurry. In relation to sex, the differences were that gilts tended to grow slower (0.96 vs 1.02 ± 0.03 kg/d; P<0.10) and showed paler meat (49.1 vs 50.1 ± 0.47; P<0.05) (lower lightness) with higher protein content than boars (23.7 vs 23.1 ± 0.12%; P<0.05). Also, boars demonstrated better capacity to retain N (22.4 vs 25.0 ± 0.59 g/d; P<0.05), but a lower fecal consistency (31.2 vs 28.9 ± 0.64; P<0.01) and a slightly higher total VFA (304 vs 308 ± 14.4 µmol/g DM) and butyric acid concentration (9.78 vs 10.69 ± 0.41%) in the feces (P<0.10) than gilts. In conclusion, YSE can be included in pigs’ diet during the finishing period, regardless of sex, without affecting their performances, with promising results on the environmental impact.