Two experiments were conducted to determine the effects of heat damage, achieved by autoclaving, on the nutritional composition and on the standardised ileal digestibility (SID) of amino acids in sunflower meal (SFM) and cottonseed meal (CSM) fed to growing pigs, reports F.N. Almeida from the University of Illinois, Urbana and co-authors there and from Evonik based in the US and Germany.

In a paper in Journal of Animal Science, they explain that a second objective was to establish a relationship between the concentration of SID amino acids in SFM and CSM and the concentration of fibre components, reducing sugars and amino acids.

In Experiment 1, 10 growing pigs (initial bodyweight 23.1±1.3kg) were surgically equipped with a T-cannula in the distal ileum and allotted to a replicated 5×5 Latin square design with five diets and five periods in each square.

A common source of SFM was separated into four batches that were either not autoclaved or autoclaved at 130°C for 20, 40 or 60 minutes. Four diets (approximately 14.5 per cent crude protein) that contained each of the four batches of SFM were formulated, and SFM was the only source of crude protein and amino acids in the diets.

A nitrogen-free diet that was used to determine the basal endogenous losses of crude protein and amino acids from pigs was also formulated. Each period consisted of five days of adaptation to the diets followed by two days of ileal digesta collection.

The SID of lysine in SFM was reduced (linear, P< 0.05) from 83.2 per cent in non-autoclaved SFM to 63.5 per cent in SFM autoclaved for 60 minutes at 130°C.

The concentrations of total lysine and reducing sugars in SFM may be used as predictors (R²=0.85) of the concentration of SID lysine in SFM.

In Experiment 2, 10 growing pigs (initial bodyweight: 35.0±1.5kg) were surgically equipped with a T-cannula in the distal ileum and allotted to a replicated 5×5 Latin square design with five diets and five periods in each square.

A source of CSM was separated into four batches that were either not autoclaved or autoclaved at 130°C for 15, 35 or 60 minutes. Four diets (approximately 13.4 per cent crude protein) containing CSM as the only source of crude protein and amino acids were formulated.

A nitrogen-free diet was also formulated and used as described for Experiment 1.

The SID of lysine in non-autoclaved CSM (66.2 per cent) was greater (P<0.05) than in autoclaved (60 minutes at 130°C) CSM (54.1 per cent).

The equation (R²=0.68) that best predicted the concentration of SID lysine in CSM included the concentration of ADIN.

Almeida and co-authors concluded that heat damage reduces the SID of amino acids in SFM and CSM. For SFM, the concentration of SID lysine may be predicted from the concentrations of total lysine and reducing sugars. The concentration of Acid Detergent Insoluble Nitrogen (ADIN) may be used to predict the concentration of SID lysine in CSM.

Reference

Almeida F.N., J.K. Htoo, J. Thomson and H.H. Stein. 2014. Digestibility by growing pigs of amino acids in heat-damaged sunflower meal and cottonseed meal. J. Anim. Sci. 92(2):585-593. doi: 10.2527/jas.2013-6769

February 2014