Fattening Lambs: starting off on the right foot with live yeast

Farmers are aware that the first weeks of a young ruminant life, and as a matter of fact, the success of weaning, are crucial to its future performance and health. It is in the first days after birth that the rumen is colonised and its microflora established. This microflora establishment follows a particular sequence. However, in current animal production systems, separation of the young animals from their mother occurs very soon after birth and transition from milk to solid feed happens before the end of the microbial colonisation of the rumen, when the ecosystem is not stabilised yet. This may lead to many digestive disorders in the young ruminant and could represent a handicap for its future development.

One of the documented effects of ruminant specific yeast SC I-1077 (Levucell® SC), recently authorised as a feed additive in Lambs by the European authorities, is to promote the maturation of the rumen in young animals, by accelerating the microflora establishment and enhancing its stability. A set of production trials in lambs, backed by strong scientific evidence of the yeast modes of action, advocate the use of this ruminant specific yeast in lambs to improve weight gain and help weaning.

The benefits of ruminant specific yeast

The rumen specific live yeast (strain SC I-1077) has been selected among hundreds of natural yeast strains for its activity in the rumen. These are particularly relevant to the weaning period:

• First, as mentioned earlier, several studies (Chaucheyras-Durand F. and Fonty G., 2001 and 2002) have shown that SC I-1077 can help accelerate and stabilise the establishment of the rumen microflora in young ruminants. Rumen maturation is accelerated, and weaning is facilitated.
• Numerous scientific studies have shown that this yeast strain improves fibres digestibility in the rumen and thus optimises the diet feed efficiency.
• Finally, SC I-1077 is largely documented for its effects on rumen pH stabilisation and the prevention of rumen subacidosis.

Not only has the ruminant specific live yeast activities and mode of action benefited from 15 years of research and over 40 scientific publications, but proof of its benefits have been made in the farms. We report here on some of the latest production trials performed in lambs. Most of these trials were part of the European dossier and their results lead to the official recognition by the authority of Levucell SC efficacy in lambs to “produce a beneficial effect on lambs final weight and average daily gain.”


Efficacy trials: the proof by 6

Production trials conducted between 2003 and 2007 in France, Spain and Italy are summarised in table 1 (1020 animals in total). All show a significant improvement of average daily gain when lambs were fed the ruminant specific yeast.

The level of improvement varies depending on the trial. These variations are to be linked with the trials conditions: in order to be significant for the European dossiers, the performance trials are performed under various conditions, representative of the EU various production systems. The trials, performed in some of the main lamb production areas of Europe (France, Italy, Spain), cover various species, destined to meat and milk production, on different types of diets and different breeding conditions (age and weight at weaning etc.). As with any other probiotics, which effects are linked to a set of complex biological activities and interactions, the effects of live yeast depend on many variables, linked to the animal, the diet or the environment, explaining the variability among trials.

Taken together, these trials show an average increase of ADWG of +9.1% (weighted mean). See table below.


Levucell SC and milk production

Numerous trials in dairy sheep, were the live yeast is authorised since 2007, have shown good response to Levucell SC, with an increase in milk yield of around 10% on average, without reduction of fat and protein contents. Production trials have also reported a reduction of somatic cells counts in sheep, testifying an improved health status.

In dairy cows, where over 30 production trials have been performed, Levucell SC increases milk yield and improves feed efficacy. It is also proven to reduce acidosis risks, in particular with high energy diet or during stress periods. Bach A. and al. (2005) went further than a pH modulation effect and showed how Levucell SC affects feeding behavior: feed intake is more frequent and more regular.


In conclusion, the ruminant specific live yeast proves to be a profitable natural solution to enhance growth in lambs. This is probably due to its ability to help establish a good rumen microflora from the start, which will be determinant for the rest of the animal life cycle, and its proven effect of feed utilisation (improved fiber degradation).

Trial # 1 France 2007

This trial was conducted in the South of France (Roquefort cheese production area), between December 2006 and January 2007.


The trial

Trial duration:
58 days, until the first slaughters

Animals:
166 Lacaune lambs, randomly allocated to two groups, Control (C) and Levucell SC (LSC). Animals average live weights between the two groups were equivalent.

Individual live weight were measured at arrival in the farm and prior to departure. Feed intake was estimated per feeding period and treatment. Morbidity and mortality were also recorded.

The diet:
Lambs were fed ad libitum a two-phase diet: starter feed during the first three weeks and grower feed until slaughter.


Lamb diets compositions

Diet analysis values, in %DM

Results

Final weight:
Lambs average final weight increases by 3% when fed the live yeast, as compared to the control group (with an extra 1.44 kg per animal on average).

Moreover, at the last weighing, the standard deviation within the live yeast group is smaller than for the control group, reflecting a more homogeneous growth at the end of the fattening period.

Average Daily Weight Gain:





Effects of Levucell SC treatment on lambs average daily weight gain (ADWG).

During the first period of the trial, ADWG is equivalent for both groups. In the grower-finisher phase, however, the lambs fed the live yeast showed an ADWG superior to the control diet by 9.2%, equivalent to 30 grams/day on average (P<0.05).

The overall daily weight gain increase is +5% during the whole trial (equivalent to an extra 17g/day/lamb) (P<0.1).