In times of high feed costs the improvement of the creatine status of fattening pigs permits a reduction in dietary energy. Guanidino-acetic acid supplemented to pig feed optimises the creatine status of the cells and enhances cellular energy efficiency.
Creatine plays a central role in the cellular energy metabolism and homeostasis by storing and transporting high energy phosphates through the cell. Those phosphates are transferred to ADP to regenerate ATP in places where ATP is used to supply energy. Due to its storage function, creatine, or rather the phosphorylated form, phosphocreatine, is similar to a cellular battery pack supplying energy without the need for any substrate-bound (an)aerobic energy production.
Creatine is predominantly found in tissues with high and fluctuating energy demand like skeletal muscle (~95%), but could be detected in most other organs as well (brain, testes, etc.).
As tissues are part of an omnivore’s natural diet, creatine is a metabolite present in their evolutionarily imprinted feeds. Since the usage of animal products is continuously reduced, and the animal-based components most commonly highly processed, there is hardly any creatine left in modern feeding systems. The animals are therefore forced to synthesise all their creatine endogenously from the amino acids arginine, glycine and methionine.
It has been shown that supplementing creatine or its metabolic precursor guanidino-acetic acid (GAA) to diets of humans or animals can replenish the diets with creatine and alters the available creatine pool in the cells, this way improving physical and zoo-technical performance. GAA proved to be the better source of creatine in animal feed as it can better withstand the more aggressive processing measures. The positive performance effects of creatine/GAA are presumably a result of enhancing the intra-cellular energy efficiency by increasing the available (phospho)creatine pool and the subsequent reduced necessity for substrate-based energy provision.
Success in broilers, how about pigs?
Consequently, one of the best established GAA applications in broiler nutrition is to use this increased energy efficiency by reducing the dietary energy while maintaining the same performance level. Many scientific and field trials established an energy equivalence of 0.06% GAA between 50-100 kcal (0.21-0.42 MJ) AMEN per kg final feed in broiler diets.
This is a very interesting concept in the current phase of skyrocketing feed and component prices as it increases the flexibility in feed formulation. The inclusion of raw materials with high energy contribution such as oil can be reduced to save feed costs. As the energy contribution of GAA takes place on a cellular level it is additive to other feed supplements that enhance the digestibility of feed sources such as enzymes or emulsifiers.
The following trial represents the first examination whether GAA can be used to reduce the net energy (NE) content of a grow-finisher pig diet in the same way.
Materials and methods
The trial was conducted in PigChamp Pro Europe’s trial facility in Segovia, Spain, and comprised 240 healthy pigs (Topigs TN70 × Piétrain; weight at trial’s start 37.9kg, 80 days of age), which were randomly assigned to one of three treatments:
• NC: Negative control
9.21 MJ NE/kg;
• PC: Positive control
9.42 MJ NE/kg; and
• GAA: Negative control + addition of GAA
9.42 MJ NE/kg, including 0.21 MJ/kg from 0.06% GAA.
The diets were formulated using wheat, wheat middlings, rapeseed meal, soybean meal to contain identical standard ileal digestible (SID) lysine, consequently resulting in altered SID lysine/NE ratios in the negative control. A two-phase feeding system was applied with:
• phase 1 (grower pigs) from 80 to 115 days of age (17.5% CP); and
• phase 2 (finishers) from 115-150 days (15.0% CP).
With an age of 150 days the first animals reached the slaughter weight of ~105kg and the trial was concluded.
Compensation for the energy reduction
Table 1 shows the results on zootechnical performance during the experiment. Due to Covid-restrictions, only marginal slaughter parameters were accessible and were therefore excluded from evaluation.
Generally, animals can cope differently when facing low levels in dietary energy. Logically, a drop in performance, i.e. reduced gain could be one of the outcomes. Alternatively as the pigs try to feed their energy requirement they might increase the feed intake to consume the same amount of energy to reach their genetic growth potential.
The second coping strategy was to be observed in this trial. All pigs showed similar weight gains and reached the similar slaughter weights within the same time. However, the animals of the negative control group had to significantly increase their feed intake to reach the same energy intake and maintain growth on the same level as the other two groups. That is a clear indication that the dietary energy was reduced to a level that forced the pigs to adapt in the NC group.
On the other hand, both the animals in the PC group as well as the GAA group animals maintained similar levels of feed intake. The pigs of those groups therefore received comparable energy levels. The addition of GAA must have improved the cellular creatine pool resulting in enhanced intra-cellular energy efficiency.
That energy contribution reduced the need for currently expensive dietary energy. All in all, 0.06% of the product Creamino (AlzChem, Germany) could therefore contribute 0.21 MJ NE/kg of feed in this trial.
Most likely, this is the first trial proving that the well-established poultry application, using GAA to spare dietary energy, could be transferred to finishing pigs. The supply of cellular physiological energy by improving the creatine supply of the animals allowed the reduction in dietary energy. Therefore, 0.06% of Creamino could spare 50 kcal NE/kg. Future studies should confirm that finding as well as examine the full energy sparing potential of GAA in grow-finishing pigs.
The application of GAA increases a nutritionist’s flexibility in formulating diets. As components with high energy contents such as oil are very high cost, reducing their inclusion by adding GAA delivers consistent economic benefits when producing grow-finishing pigs.