GAA does not provide energy saving effects in broilers

Under experimental conditions, guanidino acetic acid (GAA) has been shown to provide no energy saving value in the feed. This article will deepen the study and the surprising results.

What do we know about guanidino acetic acid (GAA) and its impact on energy metabolism?

GAA is synthesized in the kidney using glycine and arginine. Then, the GAA is transferred from the kidney to the liver where it is methylated to creatine using s-adenosyl methionine (SAM). Carnosine is an important molecule in the energy homeostasis of muscle. GAA is linked to more efficient use of energy in broilers. Although the AME content of GAA is approximately 2466 kcal / kg, the GAA would provide 83000-166000 kcal / kg of AME in broilers (a huge number compared to usual energy sources, see Figure 1) which is equivalent to a reduction of 50-100 kcal / kg of feed by adding 600 grams of GAA per tonne of feed. Is it true ? To answer this question, the energy saving effect of GAA is tested in a trial using 1,200 Ross 308 male broilers. In 5 treatments (16 pens each 15 birds), a positive control group with normal energy levels (2960, 3050 and 3150 kcal / kg during the start-up, growth and finish phases, respectively) was compared to 2 diets having either 50 (CL1) or 100 (CL2) kcal minus AME. The next 2 diets contained 50 or 100 kcal less of AME, but supplemented with 600 or 1200 grams of GAA to cover the lack of energy assuming the energy claim of GAA to be true. Broilers were monitored for their performance and slaughter parameters.

Figure 1 – Comparison of GAA’s energy saving claims with its actual AME content and some common energy sources.

GAA does not provide energy saving effects in broilers

Click to enlarge the image

Body weight was not affected by GAA

Mortality was not affected by any of the treatment groups. Body weight on days 0, 10 and 24 was also not affected by the treatment groups. On day 35, birds in the 600 gram GAA (-50 kcal + 600 gram GAA) group had a lower body weight than in the NC1 (-50 kcal) group (PTable 1).

Table 1 – Average body weight of birds at the end of the start-up, growth and finish phases.

GAA does not provide energy saving effects in broilers

The P value shows a difference from the control group. The significant difference (sign diff.) Is a multi-firm between the treatment groups.

Click to enlarge the image

Food intake was not adversely affected by GAA

Food intake was not affected by a 50 or 100 kcal / kg reduction in dietary energy (Table 2). In the start-up phase, the addition of 1200 grams of GAA per metric ton of a feed containing -100 kcal / kg of energy resulted in a reduction in feed intake. In the finishing phase and during days 0-35, a similar reduction in food intake occurred when birds were fed a diet lacking 50 kcal / kg of energy and supplemented with 600 grams of GAA per tonne of food compared to the reference diet (- 50 kcal / kg).

Table 2 – Average daily feed consumption of birds at the end of the start-up, growth and finish phases.

GAA does not provide energy saving effects in broilers

The P value shows a difference from the control group. The significant difference (sign diff.) Is a multi-firm between the treatment groups.

Click to enlarge the image

The FCR has not been improved by the GAA

The FCR was not affected by treatments during the grower, finisher, or the entire growing period. During the start-up period, a reduction in energy of 100 kcal resulted in an increase in FCR, but the other groups remained unresponsive (Table 3). Slaughter data demonstrated that breast meat weight did not respond to any of the treatment groups (Table 4). The reduction in energy by 50 or 100 kcal had no impact on the live weight of the slaughtered birds or on their carcass weight. Adding 600 grams of GAA per metric tonne to a diet devoid of 50 kcal of energy had a negative impact on bird body weight and body weight compared to the positive control or diets containing -50 or -100 kcal of energy. Leg weight increased when the diet lacked energy (-50 kcal), although -100 kcal did not create a similar response. Adding 600 grams of GAA per metric ton to a diet devoid of 50 kcal of energy further reduced leg weight.

Table 3 – Feed conversion rate of birds at the end of the start-up, growth and finish phases.

GAA does not provide energy saving effects in broilers

The P value shows a difference from the control group. The significant difference (sign diff.) Is a multi-firm between the treatment groups.

Click to enlarge the image

Table 4 – Slaughter data (in kg) of poultry at the end of the finishing phase.

GAA does not provide energy saving effects in broilers

The P value shows a difference from the control group. The significant difference (sign diff.) Is a multi-firm between the treatment groups.

Click to enlarge the image

Any substance can claim 50 kcal of energy saving

The response of broilers to different energy levels is highly dependent on the magnitude of a higher or lower energy content. Recent literature has used 125 to 150 kcal / kg of lower or higher energy food to see an energy response. Others have taken it a step further and have used True Metabolized Energy (TRE) and measured the ETM of their raw materials to make sure they will see an energy response by increasing their accuracy. Lower magnitudes (25-50 kcal AME) have often led to the conclusion that birds do not respond to different energy levels. Here, we also did not observe a clear response of broilers to -50 or -100 kcal of AME in their diet compared to the positive control group, with the exception of FCR in the initiation phase causing a Higher FCR; an effect which was not observed in the growth and finishing phase.

GAA is suggested to improve energy homeostasis in muscle tissue due to data showing excess creatine phosphate and free creatine in muscle tissue. This is often misinterpreted, giving GAA an AME value of 83,000 to 166,000 kcal / kg. There is controversy in the literature about the energy saving effect of GAA. On the one hand, a negative impact of GAA on growth parameters is observed especially under insufficient or sufficient methionine levels. In contrast, a positive impact of GAA is concluded when it is added in addition to an energy-deficient food. Here, adding GAA to a low-energy diet had no positive impact on performance parameters.

Take away message

Measuring the impact of energy on broiler performance parameters is a factor in the magnitude of changes in feed energy. A reduction or increase in dietary energy levels below 125-150 kcal AME / kg is a challenge to be measured in broilers even under experimental conditions. In this study, GAA did not provide any energy saving value in the power supply. Thus, it is not recommended to consider an additional energy matrix value for GAA higher than the AME content of GAA (~ 2466 kcal / kg).

References are available on request

Author:
Dr. Behnam Saremi CJ Europe GmbH


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