Biology Reference
In-Depth Information
temperaments is swinging the pendulum the other way and concerns have
now shifted to problems associated with a loss of beneficial foraging and
maternal traits in calm cattle.
In both the United States and Australia, cattle are grain-fed in large
outdoor feedlot pens. During the 1970s, the first author never observed
tongue rolling or other abnormal behaviors in grain-fed cattle. In a 1996 visit
to several large feedlots, she noticed an increase of “stereotypic” (abnormal)
tongue rolling in fed Holsteins. Some Holstein steers obsessively lick fences,
gates or other surfaces in the feedlot pen. This behavior is expressed even
though cattle were fed (ad lib.) grain and corn. Licking is so obsessive that
Holstein steers learned to lick open gate latches. Beef-breed cattle in feedlots
never engage in constant licking or tongue rolling.
Both authors speculate that continuously selecting for high milk produc-
tion and increased appetite may explain the increase in licking and tongue
rolling. A large amount of food is required for Holstein cows to produce
such large amounts of milk, and the effects of increased appetite are also
revealed in male offspring of these cows. We further hypothesize that licking
fences and gates may be a precursor to more serious problems if genetic
selection for the highest production is continued. For example, the increased
incidence of “weaver” condition in Holsteins is possibly related to increased
selection for high milk production. Weaver is an inherited degenerative
mycloencephalopathy ( Freeman and Lindberg, 1993 ).
From a welfare standpoint, grain-fed Holstein steers are probably not
compromised, but from a health standpoint, welfare problems already exist.
The first author has observed that Holstein steers on a high brain ration bloat
more often compared to beef breeds on similar rations. In addition to bloat,
grain-fed Holsteins have more sudden death than beef cattle. Feed yard
employees have observed healthy-appearing Holsteins suddenly fall over and
die while standing at a feed trough.
MUSCLE GROWTH AND WELFARE
In the first edition of this topic we discussed the compromised welfare of
poultry by genetic selection for rapid growth and high meat production.
Growth of the skeleton and the internal organs can not kept up with the
growth of muscle mass in broiler chickens selected to grow very quickly,
resulting in lameness and leg deformities (Muir, Chapter 9). Today, a combi-
nation of selective breeding and changes in feeding practices has reduced leg
problems. For example, a lower-energy feed is given to young chicks to
slow down growth slightly and allow the leg bones to develop. However,
broiler chickens continue to have reduced cardiopulmonary capacity in rela-
tion to their muscle mass, and cannot withstand much physical exertion
( Broom, 1987, 1993; Julian, 1993; Julian et al., 1986 ). Heavy broilers have
little stamina, and lie down after walking a few meters. Reproductive fertility
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