The effects of flavored rope additives on commercial pen-based oral fluid yield in pigs

Abstract

Abstract Oral fluid (OF) can be easily collected from pens of pigs and used for the diagnosis of a number of key endemic swine diseases or biomarkers of stress or metabolic state. Large OF volumes may increase the capacity for diagnostic testing by enabling more components to be tested for in a single pen-based sample. It is known that acidic and pleasant-tasting compounds can stimulate salivary secretion in humans. The present study investigated the effect of using flavored rope additives (apple juice, pineapple juice, and sucrose solution) on pen-based OF yield, based on their citric acid content and palatable taste. Flavored and control ropes were presented to 4 commercial pens, each of weaner and finisher pigs, according to a Latin square design across 2 replicates. Ropes were presented for 30 minutes, allowing pigs to chew the ropes and deposit OF. The OF was extracted from each rope by handwringing and subsequent centrifugation for measurement of the total volume deposited during presentation. Analysis of variance confirmed that the use of flavor had no significant effect on OF yield for weaner ( F (3,22) = 0.01, P = 0.998) or finisher ( F (3,22) = 0.53, P = 0.668) pigs. A decrease in the OF volume deposited by weaners was observed after trial day 1 ( F (3,22) = 3.67, P = 0.028), but the opposite time pattern was seen for the finisher pigs, with a progressive increase in OF volume deposited across the 4 trial days ( F (3,22) = 6.19, P = 0.003). Approximately 20 mL of fluid was yielded from each rope presentation, and a 2-sample t test confirmed that pig age had no effect on OF deposition. The results suggest that citrus or sweet flavored rope additives are unlikely to affect pen-based pig OF yield via salivary stimulation. However, suitable OF volumes for multiple diagnostic tests can be obtained from both weaner and finisher pigs by the simple handwringing of ropes after presentation.