in excretion rates (Schwarzenberger et al .,
1996). Table 17.3 shows the calculated total
daily excretion of oestrogens for cattle, pigs and
sheep (Lange et al ., 2002).
Degradation of oestrogens is a complicated pro-
cess and may include deconjugation, dissipation
and mineralization (Ternes et al ., 1999; Lee
et al ., 2003; Jacobsen et al ., 2005). Photo-
degradation has also been suggested as a mecha-
nism of oestrogen dissipation and mineralization
(Mitamura et al ., 2004; Feng et al ., 2005).
Conventional manure handling systems are not
designed to treat manure, but during prolonged
storage the degradation of hormones can occur
under anaerobic conditions.
As are endogenously produced steroidal hor-
mones, exogenous natural or synthetic hor-
mones administered to livestock are excreted in
faeces and urine (Schiffer et al ., 2001; Wilson
et al ., 2002). Zeranol and its metabolites appear
in manure, with concentrations highest imme-
diately after implantation (Baldwin et al ., 1983;
Dixon et al ., 1986; Jansen et al ., 1986). Zeranol
concentrations in manure declined steadily dur-
ing the period 20-70 days, but were still detect-
able 120 days after implantation. About 10%
and 45% of the implanted zeranol in steers was
excreted through urine and faeces, respectively
(Sharp and Dyer, 1972). Excretion of MGA is
primarily through the faeces, but little data are
available on persistence of excretion following
cessation of administration. Tracer studies using
radio-labelled MGA revealed that 60% of the
dose is excreted (intact or as metabolites) in the
faeces and 10% in the urine (Krzeminski et al .,
1981). For TBA, between 1.5 and 25% of the
dose is excreted (average 8%; Schiffer et al .,
2001), mostly as the metabolite 17a-TBOH
(Pottier et al ., 1981). This alpha form is the less
biologically active of the two primary metabo-
lites of TBA.
Degradation in storage
The concentration of E1, E2a and E2b was
475, 98 and 104 ng l −1 , respectively, in liquid
dairy manure stored in a lagoon for 8 months.
The total amount of all oestrogens in the stored
manure represented only 0.2% of estimated
accumulation of oestrogens during 8 months
of storage suggesting substantial degradation
of oestrogens during storage in the lagoon
(Zhao et al ., 2010). Oestrogen concentrations
decreased significantly in broiler litter at pH 5 or
7 after 1 week (Shore et al ., 1995).
Yang et al . (2010) reported the degradation
of steroid hormones (E2
, progesterone and tes-
tosterone) in swine manure by manure-borne
bacteria. Oestradiol, progesterone and testoster-
one were completely degraded by 9, 17 and 21 h,
respectively. In swine manure piles created over
5 days, the concentration of E1 was higher than
that of E2b (29.4 versus 0.64 mg kg −1 dry
weight) indicating the degradation or transfor-
mation of higher-degree oestrogens into E1;
thus the oestrogen profile of manure piles or pits
may not represent the actual proportion of oes-
trogens in fresh manure (Derby et al ., 2011).
The half-lives of the two metabolites of
TBA (17a-TBOH and 17b-TBOH) were 267 days
in liquid cattle manure (Schiffer et al ., 2001).
Melangerol acetate was relatively stable in
Degradation of steroidal hormones in
manure during storage
The ultimate fate of manure nutrients is strongly
influenced by how that manure is removed from
the animal facility and how (and whether) it is
stored; the same is true of steroidal hormones.
Table 17.3. Estimation of total daily oestrogen excretion by farm animals (μg day −1 ). Adapted from
Lange et al . (2002).