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GENERAL DISCUSSION
IMPLICATIONS FOR IN VITRO MATURATION MODELS IN THE BOVINE
In vitro experiments focusing on the direct effect of specific FA on oocyte
maturation and embryonic development have opened new perspectives to the
knowledge of FA feeding. More specifically, Leroy et al. (2005) indicated the detrimental
effect of saturated FA as compared to their unsaturated counterparts in an in vitro
maturation model. Aardema et al. (2011) showed that 18:1 cis-9 is able to alleviate the
detrimental effects of saturated fatty acids in vitro.
It might be important to mention that both studies used ethanol and bovine
serum albumin (BSA) respectively, to add the specific FA to the in vitro maturation
media which mimics the in vivo presence of NEFA in the FF. More recently, FA
supplementation during in vitro bovine maturation showed contrasting results as
supplementation of 18:2n-6 hampered (Marei et al., 2010) whereas 18:3n-3 (Marei et al.,
2009) and 20:4n-6 or 20:5n-3 (Marques et al., 2007) enhanced the developmental
capacity of oocytes. In all aforementioned studies, FA were added to the medium as if
they were NEFA; therefore we would argue whether these in vitro experiments mimic
the in vivo situation when feeding these specific FA to dairy cows. From the results of
Chapter 5.2, it can be clearly seen that only a small proportion of these FA are present in
NEFA as opposed to CE and PL. In vitro results on the direct effect of specific FA on in
vitro oocyte maturation and embryonic development might not always mimic in vivo
responses (Santos et al., 2008) but can help understanding contrasting in vivo
observations. The latter was shown by Fouladi-Nashta et al. (2009) feeding different FA
sources to examine the developmental potential of oocytes in high yielding dairy cows.
From their results it was concluded that the ovary is capable of buffering oocytes against
the effects of fluctuations in plasma n-6 and n-3 FA, resulting in only modest effects on
their developmental potential.
Further research is needed to understand the different effects of mobilized
(NEFA) and absorbed (mainly in PL and CE in HDL) FA on the developmental capacity of
oocytes.
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