Page 118 - The Welfare of Cattle

breedInG and WeLfare 95

Utilizing an objective metric of animal welfare will be imperative as we continually reassess our
expectations and moral framework regarding food animals. As human societies change, the ethical
frameworks surrounding the interpretation of the scientific evidence as to what constitutes appro-
priate animal care and welfare will change. Meanwhile, the constant component, irrespective of
human interpretation of the science, is the importance of the individual animal’s experience. Many
of the factors that are considered important to good animal welfare (e.g., emotions, quality of life,
injury) are either (1) only possible to experience at the individual level or (2) can change drastically
throughout the course of a day, week, or lifetime. Therefore, it is important to identify and propa-
gate individuals that are well adapted to and have the skills to thrive in their current management
environment.

Implications of Genetic Selection and Biotechnology on animal Welfare

In the livestock industry, welfare may be defined as the physical and mental health of the animal
as expressed through biological functioning and behavior. This requires the producer and members
of society to think about welfare from the perspective of the animal since it is the animal’s percep-
tion and subsequent interactions with the environment that impact its health and well-being. The
impact of conventional breeding, genomic selection, and other advances in biotechnology on animal
welfare are explored in this chapter with respect to how they influence health and well-being, and
production efficiencies in animal agriculture. Biotechnology is defined as technology based on biol-
ogy and the application of scientific and engineering principles to the processing or production of
materials by biologic agents to provide goods and services.
Genetic selection in animal agriculture is a double-edged sword. Targeted selection of traits in
agricultural animals can either challenge or enhance animal welfare by emphasizing traits associ-
ated with (1) productivity, (2) health and disease control, (3) social tolerance, (4) physical size and
morphology, (5) behavior and stress responsivity, and (6) heat tolerance. Agricultural animals are
housed in increasingly larger groups, are physically larger, are more efficient, are being provided
with more complex and dynamic environments with which to interact, and are being managed on a
planet that is experiencing climate change. Therefore, identifying phenotypes, and their respective
genotypes, that promote harmony between the animal and its production environment will ulti-
mately enhance animal welfare while supporting the sustainability of our food system.
The emphasis on selecting solely for increased productivity has unintentionally yielded
undesirable consequences that impair animal welfare. Selection for productivity in broiler chickens
has inadvertently, and negatively, impacted survival (Havenstein et al., 1994), reproduction (Liu
et al., 1995), and immune performance (Miller et al., 1992). Boars selected for high-lean tissue
growth rates (Sather, 1987) and those selected for greater fat depth (Webb et al., 1983) had weaker
legs. Laying hens selected for high productivity are less likely to thrive in large groups because they
are more likely to perform feather pecking and cannibalism (Rodenburg and Koene, 2007). Pigs
selected for fast growth are more likely to perform tail biting (Breuer et al., 2005) and are more
aggressive during mixing events (Løvendahl et al., 2005). Selection for dairy cattle with higher
milk yields has been associated with reduced fertility, higher rates of mastitis, decreased longev-
ity (Oltenacu and Broom, 2010), and reduced tolerance for heat (Ravagnolo and Misztal, 2000).
Therefore, while breeding choices are made in an effort to enhance the sustainability and efficiency
of the food system, in some instances we have unintentionally created welfare challenges for the
animals in our care.
Fortunately, genetic selection is a tool to optimize welfare and enhance productivity. Aggression,
social tolerance, the prevalence, and the location of skin lesions are heritable in swine (Turner et al.,
2009); thus, this phenotype can be used to select for individuals that are more socially tolerant
and will fight less during and after mixing. Dairy cattle have been selected for high tolerance to
human handling (Boissy et al., 2005) which can subsequently promote a positive human–animal