Agriculture Reference
In-Depth Information
given the number of instances where there is no difference,
taken at face value, these empirical comparisons do not
provide a convincing case for regarding daily intakes by
goats as being higher than those of sheep. However, these
data should be treated with some caution, for a number of
reasons. First, there is a wide range of goat and sheep
genotypes involved in the comparisons, and even when
live weights are reported, it is very diffi cult to assess the
extent to which the animals have reached mature weight,
or whether there are differences in body condition between
the goats and sheep involved in the comparison. Both rela-
tive size (current weight as a proportion of SRW) and body
condition will affect intake (NRC, 2007; CSIRO, 2007).
Moreover, for the fi eld studies (Pfi ster and Malechek,
1986; Papachristou, 1994), the diet composition differed
between goats and sheep and was thus confounded with
animal species.
Hence without further corroborating evidence, one
cannot yet conclude that goats and sheep differ in volun-
tary feed intake. Although there seems little doubt that the
feed intakes required to maintain live weight are higher in
goats than sheep, the issue of whether goats have higher
voluntary feed intakes is still unresolved.
Goats in general have a strong preference for dry feed
to be in the pelleted form rather than fl our or meal
form (Morand-Fehr, 2003; Bateman et al., 2004). The
main reason for this seems to be the irritation caused to
the upper respiratory tract by the consumption and inad-
vertent inhalation of fi ne, dry feeds. This preference
appears to apply equally to young goats (Bateman et al.,
2004) as well as to adults (Morand-Fehr, 2003) and in part
also relates to the fact that pelleted diets allow a more rapid
eating rate. As might be expected, pelleted rations that
consist of 5- to 10-mm pellets, as might be fed to sheep,
are preferred by goats to larger pellets (15
20 - mm) typical
of the kind fed to cattle (Pinkerton and Pinkerton, 2008).
Goats prefer dry diets fed in meal/fl our form to have
slightly higher moisture content because this allows a
degree of agglomeration and, again, a faster intake rate
with less irritation (Morand-Fehr, 2003). However, liquid
diets such as those based on molasses do not appear to be
preferred by young goats (Bateman et al., 2004).
When trough-fed, housed goats consume both “main
meals,” which account for the bulk of their intake, and
smaller “secondary meals.” Main meals usually occur
immediately after feeding, and the amount consumed will
be a function of the rate of intake which the ration permits.
The manager must therefore ensure that the physical form
of the diet allows the animals to consume the desired
quantities. Housed goats will also consume a feed more
readily if they have had some previous experience of it
(Distel and Provenza, 1991).
An aspect that assumes much more importance in
housed animals than in free-ranging goats is the effect of
dominance hierarchies on eating behavior. When it comes
to consumption of feed from a trough with limited avail-
able space, the comment by Pinkerton and Pinkerton
(2008) is relevant:
−
FEEDING HOUSED GOATS,
SUPPLEMENTARY FEEDING,
DROUGHT FEEDING
Goat production systems can often rely on the natural
supply of pasture and/or browse, but there will be seasons,
years, or periods of high production when extra feed has
to be supplied by the manager (supplementary feeding) or
when animals have to be fed during drought. Under these
circumstances, questions of preference and feeding behav-
ior become even more important. In addition, dominance
hierarchies within the goat herd, which may not usually
infl uence daily management, become a major consider-
ation. The management of feeding under all of these
circumstances has a strong economic dimension, for as
Solaiman (2006) points out, from one-half to two-thirds of
the variable costs of production are those related to feeding.
Unless supplementary or drought feeding is managed well,
enterprise profi t will rapidly be eroded by the costs of
feeding. For useful and detailed discussions of feeding
management issues, the reader is referred to Bateman
et al. (2004), McGregor (2005), and Solaiman (2006).
Gracious, equitable sharing is simply not a caprine
characteristic; greed, aggression and sheer size con-
spire to “cheat” the more civil and/or smaller goats.
The manager must therefore ensure that this “greed and
aggression” is minimized, mainly by ensuring that trough
space is adequate for all goats to be able to feed. As a
generalization, 25-30 cm of trough space/kid should be
allowed, or 45-50 cm/adult. A smaller allowance of trough
space will almost certainly result in aggressive behavior
and in the more submissive goats consuming less.
Feeding of Housed Goats
The highly selective feeding of goats applies equally
indoors, though goats that are too hungry or too full will
discriminate less between feeds (Morand-Fehr, 2003).
Supplementary Feeding under Field Conditions
A number of the above comments about the feeding of
housed goats apply equally well under fi eld conditions,
