Table 2.

Comparison of two saliva collection methods.

Collection Methods	Type of Collected Saliva	Volume of Collected Saliva (mL/day/pig)	hNGF/pNGF Concentration (µg/mL)
UPDCB (Surgical) *	Parotid saliva	512 ± 84 †	14.2 ± 3.9/0.04 ± 0.02
BLDB (Nonsurgical) ‡	Oral saliva	303 ± 76 §	4.5 ± 0.7/0.02± 0.01

The hNGF-TG pigs used for testing the saliva collection methods were five to six months old. They were fed two meals (about 1.2 kg of feed per meal) per day at 8:00 am and 4:00 pm, respectively. * The operation of the surgical saliva collection method is shown in Figure 2. Formal saliva collection testing was conducted on TG pigs at 3 days post-surgery. ^† 80 to 90% of the total volume of collected parotid saliva was secreted by the TG pigs during their feeding time (about 18 min per meal). ^‡ The operation of the nonsurgical saliva collection method is shown in Figure 3 and Supplementary Video S1. ^§ The volume of total oral saliva collected within 2 h during feeding per day (1 h per meal). For testing of the nonsurgical method, TG pigs were fed with about 0.6 kg of feed at the beginning of each meal to induce parotid saliva secretion, after their oral saliva was collected by the BLDB method for a half hour, TG pigs were again fed with about 0.6 kg of feed, and then their oral saliva was collected by the BLDB method for another half hour. Before formal saliva collection testing, TG pigs were trained for 7 days to let them get used to wearing the nonsurgical saliva collection device.