Agriculture Reference
In-Depth Information
As early as 1945, there were indications that consumption of ergotized barley by late-
pregnant sows had a detrimental effect on mammary development. Almost no mammary
development was present in sows consuming the ergotized barley whereas all control
sows had a normal mammary development (Nordskog and Clark, 1945). A negative
impact of ergots on mammary development when fed for 8 days prior to farrowing
was also reported more recently (Kopinski
et al.
, 2007). The normal prolactin surge
associated with parturition in the sow occurs between about 2 days prepartum through
several days postpartum (Dusza and Krzymowska, 1981). This is most interesting due to
the finding that endotoxins have an inhibitory effect on prolactin secretion during the
immediate postpartum period, thereby showing a potential relation between suppression
of prolactin and insufficient milk yield in sows (Smith and Wagner, 1984). The first
demonstration of the essential role of prolactin for mammary development in pregnant
gilts was made over 10 years ago using the dopamine agonist bromocriptine to inhibit
prolactin secretion (Farmer
et al.
, 2000). When feeding 10 mg of bromocriptine to gilts
thrice daily from days 70 until 110 of gestation, mammary parenchymal tissue mass on
day 110 of gestation was 581 g compared with 1,011 g for control animals, representing
a 42.5% decrease (Figure 4.3).
It was subsequently shown that the specific time-window where prolactin exerts most
of its stimulatory effect on mammary gland growth is from 90 to 109 days of gestation
(Farmer and Petitclerc, 2003). Feeding 10 mg of bromocriptine thrice daily to gilts during
that specific time period decreased total parenchymal mass by 46% (918.5 vs. 1,701.7 g)
on day 110 of gestation but the treatment had no effect when given from days 50 to 69 or
days 70 to 89 of gestation. Recent data showed that when creating a hyperprolactinemic
state in that specific period of late-gestation, using the dopamine antagonist domperidone,
there was a significant beneficial effect on secretory activity of mammary parenchyma and
on mammary epithelial cell differentiation (VanKlompenberg
et al.
, 2013). Subsequent
milk yield was also improved on days 14 and 21 of lactation, and piglet weight gain until
weaning was increased by 21%. Yet, no measures of mammary composition were obtained.
Figure 4.3. Transversal cut from the mammary gland of a control (C) or treated (B) gilt on day 110 of gestation.
Treatment consisted of thrice daily feeding of 10 mg of the dopamine agonist bromocriptine from days 70 to
110 of gestation.
