Genetics and Animal Welfare - Genetics and the Behavior of Domestic Animals - page 441

breeders. This does not compromise the welfare of market animals that are fed
ad lib., but it may increase welfare problems in calorie-restricted breeding ani-
mals. Studies in poultry, pigs, and cattle show that the incidence of abnormal
behavior can be reduced by providing roughage in the diet ( Lawrence et al.,
1989; Redbo and Nordblad, 1997; Robert et al., 1993; Zuidhoff et al., 1995 ).
Roughage helps to reduce stereotypies and other abnormal behavior because
diets high in roughage can be restricted in calories and fill the animal's gut.
Diets with added roughage also take more time to eat and satisfy the animal's
motivation for mouth activities. However, artificially increasing food intake
time by placing hanging chains in the feed trough failed to reduce the develop-
ment of stereotypies ( Bergeron and Gonyou, 1997 ). The wild ancestors of
chicken and pigs spent many hours pecking and rooting to obtain their food.
Stolba and Wood-Gush (1989) report that domestic swine reared in woods and
grasslands display most of the same behaviors as their ancestor, the European
wild boar. Behaviors used for obtaining food, such as grazing and rooting, occu-
pied large portions of each day. Even though the adult domestic sows used in
this study came out of an intensive housing system, they quickly reverted to
ancestral foraging patterns.
It is important to provide sows with roughage feed that provides both gut fill
and mouth activities. Feeding roughage such as straw, sugar beet pulp, or oat
hulls can improve the welfare of breeding animals kept on a calorie-restricted
diet ( Close et al., 1985 ). Zuidhoff et al.(1995) found that feeding concentrates
diluted with 15% oat hulls increased the time required to consume the feed and
reduced stress. Stress was measured with a heterophil/lymphocyte test. Diets
high in fiber (lignocellulose) were effective in reducing feeding motivation
( DeJong and Guemene, 2011 ; Souza de Silva et al., 2012 ). Chopped straw was
added to the ration and hunger was measured by counting how many times
boars would press a panel to obtain feed rewards. Whole straw provided to pigs
is more effective for reducing abnormal behavior than chopped straw.
Stereotypies in sows housed in individual stalls can be prevented by feeding
small amounts of straw ( Fraser 1975 ). Compared to baled hay, pelleting, or
wafering, roughage feeds decrease bulking by about 75% ( Haenlein et al.,
1966 ). Willard et al.(1977) found that horses fed pellet diets spent more time
chewing wood and eating manure compared to horses fed hay.
Some sectors of the industry have been reluctant to feed roughage
because roughages are too bulky to move through some types of automated
feeding systems. Roughages are also more expensive to transport and
increase the load on manure-handling systems. Management issues aside,
adding roughage to the diet improves productivity. Broiler breeder hens fed
a bulky diet of 15% oat hulls had higher egg production than hens fed grain
concentrates ( Zuidhoff et al., 1995 ).
While feeding roughage can reduce hunger motivation in some highly pro-
ductive breeding animals, it may not always be sufficient to maintain welfare.
Tina Widowski, an animal welfare specialist at the University of Guelph in