Growth performance and feed efficiency are known to be key factors in ensuring the economic productivity of a fattening unit. At the same time, global population growth is increasing the demand for protein, which has to be produced using fewer resources while achieving productivity gains and offering socio-economic and environmental benefits for producers and society as a whole. The swine industry has specific needs which must be addressed, including the ability to supply slaughterhouses and packers with quality meat while also meeting consumer demands. Nutritionists are therefore having to develop new feed formulas in response to these criteria.
Different strategies are currently under development to improve the performance of pigs from fattening up to slaughter and control the various metabolic disorders during the fattening period. One such strategy involves use of live yeast in the different fattening diets. These yeasts are believed to promote the development of beneficial flora and enable the fibrolytic bacteria of the intestinal microbiota to perform their full role when digesting certain fibres contained in feed (Kiros et al., 2016). The extra energy released from the degradation of these fibres is in turn thought to improve the performance of pigs (Lizardo et al., 2008).

In order to validate these data on improved animal performance at the different stages of the fattening period, a trial was carried out to assess the effects of live yeast supplementation in starter, grower and finisher feeds on the health status and performance of pigs up to slaughter.

1. MATERIALS AND METHODS

1.1. Experimental design

The study was conducted at a pig farm at the Futterkamp experimental centre in Germany. A total of 330 fattening pigs (Topigs N70 – DanBred – PIC x Piétrain) with an initial weight of 30.4 kg were divided into two homogeneous groups, yeast (Y) vs. control (C), according to weight and sex (n=165, 88 ♀ and 77 ♂, 15 replicates of 11 pigs). Group (C) was fed starter, grower and finisher feeds containing barley, soybean and wheat flour, including NSP enzymes but no antibiotics or probiotic-type additives. The animals in group (Y) were fed the same feed but with Actisaf^® HR+ Sc47 live yeast supplementation (Phileo by Lesaffre, France) at doses of 1.0 kg/t of feed in the starter feed and 0.5 kg/t in the grower and finisher feeds.
1.2. Measurements

The individual weight of the animals was measured at the beginning/ end of each feeding phase, and feed intake was recorded for each period. The average daily gain (ADG) was calculated in addition to the feed conversion ratio (FCR) for each feeding phase up to slaughter (99 days of fattening on average), with the 1st departure for slaughter taking place after 85 days of fattening.

Finally, the individual weight and carcass quality were measured at the slaughterhouse.
1.3. Statistical analyses

Statistical analyses were performed using version 9.4 of the SAS software, with the pen as the experimental unit. The performance parameters were analysed using the MIXED procedure, with the group and sex as fixed parameters. The weight and carcass quality were evaluated using AutoFOM III. All analyses were carried out at the 5% confidence level.

2. RESULTS

2.1. Animal performance

With the exception of the grower period, a significant improvement was observed in ADG up to 1st slaughter in group (LY) compared to group (C) (904 vs. 869 g/d respectively; p = 0.002) and for the duration of fattening phase (888 vs. 912 g/d respectively; p = 0.03) (Figure 1).

Compared with group (C), intake in group (LY) improved just slightly in the starter (C: 1.61 vs. LY: 1.65 kg/d; NS) and grower (C: 2.39 vs. LY: 2.43 kg/d, NS) periods, but was significantly higher in the finisher phase (C: 2.83 vs. LY: 2.86 kg/d), p < 0.05). Generally, feed intake throughout the fattening phase and up to 1st slaughter was higher in group (LY) than in group (C) (2.27 kg/d vs. 2.20 kg/d respectively; p = 0.2).

In the finisher phase, the FCR was significantly reduced in group (LY) compared to group (C) (2.98 vs. 3.22 respectively; p = 0.04). Over the entire fattening period, the FCR was lower for group (LY) than for group (C) (2.53 vs. 2.57 respectively; p = 0.15) (Figure 2).

At the 1st departure for slaughter, the animals in group (LY) were heavier than the animals in group (C) (107 vs. 103 kg respectively; p = 0.10) Duration of fattening period was reduced by two days for the animals in group (Y) compared to those in group (C) (Y: 99 vs. C: 101 days).

2.2. Carcass analysis

The size and quality of cuts were similar in both groups. Slight differences were observed in belly weight, which was greater in group (LY), and shoulder weight, which was greater in group (C).
Finally, for the pigs in group (LY) the net profit for the farmer was €1.11 per slaughtered animal.

Conclusion

In 2008, Lizardo et al. demonstrated the benefits of yeast on pig performance, in particular due to the improved degradation of the fibres contained in feed. Also, yeast supports digestive flora, which in turn improves animal efficiency, thus promoting growth in optimum conditions. It is an approach that satisfies the need
for improved nutrient efficiency, an objective shared by all those involved in the industry.

This study, conducted under commercial conditions, suggests that yeast supplementation can play an important role in optimising the available nutrients, resulting in improved feed efficiency and higher growth rates. It therefore confirms the benefits of yeast supplementation in terms of boosting the fattening pig performance.