Copra and palm kernel co-products are commonly fed to ruminant animals in some parts of the world. However, very limited research has been reported on the use of these ingredients in swine diets. No values are listed in the NRC (1998) for copra expellers, palm kernel expellers, or palm kernel meal.

Copra expellers are produced when coconut oil is mechanically expelled from coconut meat, or copra. Likewise, palm kernel expellers are produced from mechanical expulsion of oil from the nut of the fruit of the palm tree, whereas palm kernel meal is produced when palm kernel oil is removed by solvent extraction. All these ingredients have relatively high concentrations of fiber and a relatively low concentration of amino acids (Table 1).

Two experiments were conducted to determine the energy value and AA digestibility in copra expellers, Asian palm kernel expellers sourced from Indonesia, African palm kernel expellers sourced from Costa Rica, and African palm kernel meal sourced from Costa Rica and to compare these values to values obtained for soybean meal.

Experiment 1: Amino acid digestibility

In the first experiment, six growing barrows (initial BW: 34 ± 1.4 kg) were randomly allotted to six diets. Five of the diets contained copra expellers, Asian palm kernel expellers, African palm kernel expellers, African palm kernel meal, or soybean meal as the sole source of amino acids. The sixth diet was the nitrogen-free diet that was used to calculate endogenous losses of protein and amino acids.

Of the experimental ingredients, soybean meal had greater (P < 0.05) standardized ileal digestibility (SID) of crude protein and all indispensable amino acids than copra expellers, Asian palm kernel expellers, and African palm kernel meal (Table 2). The digestibility of leucine, methionine, phenylalanine, tryptophan, and valine did not differ between soybean meal and African palm kernel expellers, but the SID of all other indispensable amino acids and crude protein was greater (P < 0.05) in soybean meal than in African Palm kernel expellers.

The digestibility of all indispensable amino acids did not differ between copra expellers and African palm kernel expellers, but the digestibility of crude protein and all indispensable amino acids in African palm kernel expellers were similar to or greater (P < 0.05) than the digestibility values for Asian palm kernel expellers. Asian palm kernel expellers did not differ from African palm kernel meal in digestibility of indispensable amino acids, but had greater (P < 0.05) digestibility of crude protein.

The ideal arginine:lysine ratio in swine diets has been calculated at about 1.05. The ratio in soybean meal in this experiment was close to that ideal at 1.15, but the ratio was 4.95 in copra expellers, 4.47 in Asian palm kernel expellers, 3.92 in African palm kernel expellers, and 3.78 in African palm kernel meal. This may limit the inclusion of these ingredients in diets fed to pigs because excess arginine can interfere with the absorption of lysine.

Experiment 2: Energy values

In the second experiment, 48 barrows (initial BW: 35 ± 3.0 kg) were randomly allotted to six diets. One diet was a corn-based basal diet, and the remaining five experimental diets contained 70% basal diet and 30% of copra expellers, Asian palm kernel expellers, African palm kernel expellers, African palm kernel meal, or soybean meal.

Of the experimental ingredients, soybean meal had the greatest (P < 0.05) concentrations of digestible energy and metabolizable energy, as well as the greatest apparent total tract digestibility of energy.  This is likely a result of the much lower fiber concentration in soybean meal compared with copra and palm kernel products.

The concentration of digestible energy and the energy digestibility in copra expellers were greater (P < 0.05) than in all the palm kernel products (Table 3). The concentration of metabolizable energy in copra expellers was also greater (P < 0.05) than in African palm kernel expellers and African palm kernel meal, but not different from Asian palm kernel expellers.

Among the palm kernel products, Asian palm kernel expellers had a greater (P < 0.05) concentration of digestible energy than African palm kernel expellers and African palm kernel meal. The concentration of metabolizable energy in Asian palm kernel expellers and African palm kernel expellers was not different, but Asian palm kernel expellers contained more (P < 0.05) metabolizable energy than African palm kernel meal. There was, however, no difference in digestibility of energy among the 3 palm kernel products.  

Key points

• Amino acid digestibility in copra expellers, palm kernel expellers, and palm kernel meal is less than in soybean meal.
• Copra expellers has amino acid digestibility that is not different from palm kernel expellers or palm kernel meal.
• Soybean meal contains more digestible and metabolizable energy than copra and palm kernel products.
• Copra expellers has a greater concentration of digestible energy than palm kernel expellers and palm kernel meal.
• Amino acid digestibility in palm kernel expellers is not different from that in palm kernel meal, but palm kernel expellers may contain more digestible energy than palm kernel meal.

Table 1. Analyzed nutrient composition (as-fed basis) of the ingredients

Table 2. Standardized ileal digestibility (SID) of crude protein and indispensable amino acids in copra expellers, Asian palm kernel expellers, African palm kernel expellers, African palm kernel meal and soybean meal (SBM)

^a-dValues within a row lacking a common superscript letter are different (P < 0.05).

Table 3.Digestible (DE) and metabolizable (ME) energy concentration and apparent total tract digestibility (ATTD) in copra expellers, Asian palm kernel expellers, African palm kernel expellers, African palm kernel meal and soybean meal (SBM)

^a-dValues within a row lacking a common superscript letter are different (P < 0.05).