Page 243 - The Welfare of Cattle

220 the WeLfare of CattLe

tool (ovaritome) into the vagina which facilitates the severing of the ovaries while flank spaying is
done by making an incision in the flank to gain access to the ovaries which are then removed using
a scalpel (Horstman et al., 1982; Petherick et al., 2013). Both methods are surgical procedures,
which have been shown to cause some stress and pain in heifers and cows, leading to the recom-
mendation that flank and drop method spaying should not be performed without pain management
(Horstman et al., 1982; Petherick et al., 2013). In addition, the drop method is recommended over
flank spaying as it is considered to be less invasive and was shown to cause fewer behavioral and
physiological indicators of pain (Horstman et al., 1982; Petherick et al., 2013). Research on pain
mitigation strategies for spaying is currently lacking.

WeLFare ISSUeS aSSOCIateD WIth the FINIShING FeeDLOt

The finishing phase (typically the last 100 days after backgrounding) focuses on feeding high-
grain/low-forage rations to backgrounded calves or yearlings until they reach a prescribed finish
(fat cover) before marketing for slaughter. While backgrounding cattle typically have more welfare
issues related to pre-transport management and BRD, finishing cattle have more welfare issues
related to feeding and diet.

Nutrition

Cattle are ruminants by nature, meaning they evolved consuming plant material containing fiber
required for the optimal functioning of the rumen necessary for good health and welfare. The main
focus of the backgrounding phase is to optimize growth while reducing fat disposition and this is
accomplished by feeding diets that are higher in fiber (forage) and lower in energy (grain). However,
the main goal of the finishing phase is to fatten cattle as quickly and efficiently as possible. In North
America, this has been achieved by feeding diets that are high in grain (between 60% and 95%)
but low (40% to 5%) or in some cases even void of forage. The transition from the background-
ing to the finishing diet is a challenging time which is characterized by significant changes in
the rumen microbiota which may become severely unbalanced, particularly if the transition is too
abrupt (Tajima et al., 2001). A negative welfare consequence of this rapid diet change is the accumu-
lation of acid (lactate and volatile fatty acids) which lowers the ruminal pH resulting in either acute
(pH < 5) or subacute acidosis (pH < 5.8) (Schwartzkopf-Genswein et al., 2003; Penner et al., 2011).
Both of these conditions can result in further health issues such as liver abscesses and laminitis
(Galyean and Rivera, 2003, Nagaraja and Lechtenberg, 2007). Cattle with acute acidosis become ill
and typically stop consuming feed. In more severe cases, acidosis causes thickening of the ruminal
mucosa causing lesions (rumenitis) which reduce the animal’s ability to absorb feed nutrients and
may result in death (Owens et al., 1988). Although the effects on the rumen environment, feeding
and weight gain are obvious, it is currently not known if acidosis is a painful condition in cattle.
Feedlot managers are willing to assume a certain death loss associated with nutritional disease
in order to maximize weight gain for the majority of the cattle being fed. Morbidity and mortality
rates related to acidosis are difficult to find in the literature, likely due to the difficulty in diagnos-
ing the disease in live animals. Liver abscesses found at the time of slaughter have been used as a
proxy measure for acidosis and have been reported to be as high as 56% (Fox et al., 2009). There
are several risk factors for acidosis including the length of the diet transition period, how ferment-
able the diet is, the frequency, amount and rate at which the feed is consumed (Owens et al., 1988,
Schwartzkopf-Genswein et al., 2003, Tucker et al., 2015) and, the individual’s ability to manage the
effects of high acid production (Goad et al., 1998).
In order to mitigate the negative consequences of abrupt changes from low to high-grain diets,
feed managers have developed “step-up” protocols whose main purpose are to gradually increase