This study set out to determine the apparent total tract digestibility (ATTD) of the nutrients and energy in six cottonseed meal (CSM) feedstuffs fed to pregnant and non-pregnant sows. The six types of CSM were: two expelled CSMs with crude protein (CP) levels of 40.67% and 44.64%, and four solvent-extracted CSMs with CP levels of 45.18%, 51.16%, 56.44%, and 59.63%. Fourteen gestating sows (at the fourth parity with body weights of 220.6 ± 18.4 kg at days 30 of gestation) and 14 non-pregnant sows (after the third parity with body weights of 219 ± 14.6 kg) were assigned to a replicated 7 × 3 Youden square design with seven diets and three periods. The seven diets included an entirely corn-based diet and six diets each containing 20.0% of the six CSMs tested. Each period included a 5-d acclimation to the experimental diets, followed by a 5-d period during which urine and feces were collected. Significant differences were found among the six CSM diets, regardless of reproductive stage, regarding 1) the ATTD of neutral detergent fiber (NDF) (P < 0.05) and 2) the ATTD of dry matter (DM), organic matter (OM), and CP and the gross energy (GE) (P < 0.01). Non-pregnant sows had a greater ATTD of OM and CP (P < 0.01) compared with gestating sows. The digestible energy (DE) and metabolizable energy (ME) of the six CSM samples ranged from 12.48 to 17.15 MJ/kg and 11.35 to 15.88 MJ/kg, respectively, for non-pregnant sows, and from 12.86 to 16.41 MJ/kg and 12.43 to 14.72 MJ/kg, respectively, for gestating sows. However, the DE, ME, and ME:DE ratios of each CSM were similar between gestating and non-pregnant sows. DE and ME were negatively correlated with NDF and ADF, respectively, but were positively corrected with CP level (P < 0.01). Collectively, the DE, ME, and nutrient digestibility of CSM varied greatly according to the chemical compositions, and CSMs with higher protein and lower fiber levels had greater DE and ME levels.
Keywords: available energy; cottonseed meal; digestibility; sows.
Cottonseed meal (CSM) is a high-protein feedstuff produced as a by-product of cottonseed processing. Concerns regarding the negative effects of antinutritional factors such as gossypol toxicity have limited the use of CSM as sow feed. As genetic breeding and feed processing technology improve, the potential for CSM as a supplementary protein in sow diets has increased. However, precise evaluation of the nutritive value of CSM for sows is key to accurate diet formulation. We evaluated the nutritional values of six CSMs prepared using different processing methods with different chemical compositions, fed to pregnant and non-pregnant sows, and investigated the relationships between their chemical composition and digestible (DE) and metabolizable energy (ME). We found no differences in DE and ME between gestating and non-pregnant sows for the six CSMs tested. However, there were large variations in DE and ME among the six CSMs tested, and most DEs and MEs were higher than the values published by the NRC (2012), which were measured from pigs in the growth and finishing stages. These findings demonstrate the different DE and ME values of CSM with different chemical compositions and provide a basis for precise diet formulation for sows.
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