3.2. Animal Feeding Behaviour
For a second set of experiments, rumen tissue samples were compared for
adult male deer with differences in the extent of their food begging
behaviour (i.e. likelihood of begging food from human visitors in
Phoenix Park). Animals were separated into two groups consisting of
either consistent beggars (N = 4) or rare beggars (N = 7) – with
respective feeding scores of +1.64 ± 0.23 and -1.88 ± 0.30 respectively
(p < 0.001, N=4-7, Unpaired T-Test). Initial comparisons were
made of the papillae physical measurements of tissues from both groups -see Table 2 for details. On this occasion, these data showed
that there were no significant differences in either papillae length or
papillae width. In contrast, the expected significant increase in
papillae density in the consistent beggars was observed.
Following on from this, western blotting experiments were performed
using 3 male adults from both groups. In addition, samples from two
other consistent acceptor animals, one a juvenile male and one a female
adult, were included in the experiments as controls – see
Figure 2 . Since there was some small differences in the amounts of
protein obtained for each sample, western blot signals for UT-B2 and
MCT1 were evaluated as a ratio to the amount of protein. In this case,
the 50 kDa UT-B2/protein signal ratio was significantly higher in
consistent beggars (0.56 ± 0.10, N = 3) than it was in the rare beggars
(0.13 ± 0.04, N = 3) (p = 0.0183, Unpaired T-test). Interestingly, the
increased level of UT-B2 abundance in the male adult consistent beggars
was similar to that observed in the other two beggars - one male
juvenile and one adult female. In contrast, there was no significant
difference in the 43 kDa MCT1/protein signal, which was 0.70 ± 0.11 to
0.46 ± 0.07 respectively (p = 0.1364, N=3, Unpaired T-test).
Additionally, although variable, there was also no significant
difference in the ages of the groups (p = 0.1380, Unpaired T-test), with
consistent beggars being 8.3 ± 1.9 years (N = 4) and rare beggars being
5.7 ± 0.6 years (N = 7).
In order to identify where these transporter proteins were located and
confirm their abundance, a series of immunolocalization experiments were
performed. Initial studies showed that both MCT1 and UT-B2 proteins were
predominantly located in the stratum basale layer of consistent acceptor
male adult rumen – see Figure 3 . Further experiments were then
performed with tissue sections taken from all 8 animals that had been
used in the western blotting analysis. For MCT1, moderate to strong
staining was observed in rare beggar adult males (M1-M3), whilst strong
to very strong staining was observed in the consistent beggar adult
males (M4-M6) – see Figure 4 . There was also strong staining
observed in the juvenile male (J1) and adult female (F1). In all cases,
the MCT1 staining was mainly found in the stratum basale layer. Finally,
for UT-B2 there was very little staining in rare beggar adult males
(M1-M3), in contrast to the weak-to-moderate staining in consistent
beggar adult males (M4-M6) – see Figure 5 . In particular,
strong staining was observed in the M6 sections. Similarly, stronger
UT-B2 staining was observed in the juvenile male (J1) and adult female
(F1) sections. In each case, the UT-B2 staining was located
predominantly in the stratum basale layer.