Effects of feeding sodium stearoyl-2-lactylate diets to lactating sows on performance, digestibility of nutrients, composition, and fat globule size in milk

The objective of this study was to determine the effects of feeding sodium stearoyl-2-lactylate (SSL) as a new feeding emulsifier diet with and without soybean oil (SO) on the milk fat globule (MFG) size, milk composition, digestibility of nutrients, and performance in lactating sows. Sixty sows (Large White x Landrace) were randomly assigned to 1 of 4 treatments according to a 2 x 2 factorial arrangement of treatments. Each treatment had 15 replicates composed of 1 sow. The factors included 1) the fat level (0% vs. 3% SO) and 2) the emulsifier content (0% vs. 0.1% SSL). Treatments included 1) Control (without SO and SSL), 2) SO (3% SO without SSL), 3) SSL (0.1% SSL without SO), and 4) SO +SSL (3% SO and 0.1% SSL). During the suckling period, sows in the SO +SSL group lost less back fat thickness (P < 0.05) compared to other groups; sows fed 3% SO diets consumed less feed (P < 0.05) compared to sows fed diets without SO, but there were no significant effects (P > 0.05) of dietary fat and its interaction with a dietary emulsifier on energy intake and the weaning-estrus interval. The digestibility of ether extract in the SO +SSL group was greater than in the SO group (P < 0.05). Moreover, greater digestibility of CP, Ca, and P in the SO+SSL group was observed compared to that of other groups (P < 0.05). Feeding the SO +SSL diet improved the concentrations of milk fat, protein, and total solids on d 11 of lactation compared to other diets (P < 0.05). Also, an interaction between supplemental SSL and SO was observed for the milk fat and total solids concentrations. The average diameter of MFG on d 11 of lactation was significantly decreased by the addition of 0.1% SSL compared to a diet with no SSL supplementation (P < 0.05). No significant differences among the dietary treatments were observed in cholesterol, triglyceride, high-density lipoprotein cholesterol, or low-density lipoprotein cholesterol in sows' plasma (P > 0.05). In conclusion, feeding a 0.1% SSL diet to lactating sows may decrease the average diameter of MFG and improve the digestibility of nutrients and composition of milk.