Sharp shadows, reflections, and other lighting problems in a handling facility can slow down the movement of cattle and pigs (Grandin, 1982; Klinglmair et al., 2011; Willson et al., 2021). There are differences in the types of lighting problems that may occur in outdoor and indoor facilities. In outdoor handling races and alleys, sharp shadows cast by a bright sun may increase the percentages of cattle balking and stopping. Balking is a term that is used when an animal stops and refuses to move forward when urged by a handler. During vehicle unloading in an outdoor facility, sharp high contrast shadows caused more cattle balking compared to no shadows or shadows with soft contrast (Willson et al., 2021). Figure 1 shows sharp shadows cast by the bars of the fence in a sheep facility. Piglets were also more likely to have a negative response to black and white stripes that created sharp contrast (Tanida et al., 1996). A survey of six sheep transporter drivers in Australia indicated that distractions, such as, shadows, were important problems that had a detrimental effect on handling (Burnard et al., 2015). The author has observed that a single bright sunbeam shining through a hole in a roof was associated with cattle stopping. This may explain why livestock sometimes move easily through a race or alley and at other times the animals will be difficult to move. This may occur because sometimes the sunbeam is present and at other times, it is absent. Stookey and Watts (2014) found that when cattle were given a choice in a Y-maze, the animals were more likely to choose the race where they could see light through the side of it. A common problem is cattle stopping and refusing to enter a building from an outdoor pen or corral. The author has observed that this problem is often worse on bright sunny days due to the “dark movie theater” effect. At night, the author has observed that they will often enter the same building easily, because the inside of an illuminated building is now brighter than the outside. In several large cattle veterinary handling systems, the author has improved cattle movement on bright sunny days by removing the back wall of the building and replacing it with white translucent plastic. This allowed ample natural light to enter the building.

In facilities that are completely indoors such as, slaughter plants, auctions and shearing sheds, lamps can be placed on dark race entrances to attract cattle, pigs, and sheep into them (van Putten and Elshof, 1978; Hitchcock and Hutson, 1979; Grandin, 1982, 2001; Tanida et al., 1996). Adding a lamp at a dark indoor race entrance reduced the use of electric prods from 38% of the pigs to 4% (Grandin, 2021). Livestock have a natural tendency to move toward a lighted area. In outdoor handling systems, the author has observed that they will not approach when either a rising or setting sun is shining directly into their eyes. Klinglmair et al. (2011) found that reflections and glare on wet floors increased the frequency of balking. Problems with stopping, balking and refusal to move due to lighting problems are most likely to occur in animals who are seldom handled in a particular facility. The author has observed in dairies, that a new heifer will stop at a shadow or a sunbeam the first few times she enters the milking parlor. An experienced cow has learned that the shadow and it is safe to walk over it.

There are numerous visual distractions that are associated with livestock stopping or turning back during movement through a handling system. Seeing visible people up ahead can cause problems such as, animals stopping or turning back. However, when sheep see other sheep in front of them, they are often more willing to move through a single file race. Franklin and Hutson (1982) found that sheep are more willing to move toward either a picture of sheep or fake sheep if it is facing either away from them or sideways. A sheep facing them may be perceived as a threat. Cattle that were held in a squeeze chute (crush) remained calmer when a small solid shield was installed to prevent them from seeing a person who was administering an injection (Muller et al., 2008). Pereira-Lima et al. (2018) found that removing distractions improved cattle movement. In a large slaughter plant, a solid side on the single file race improved cattle movement (Ercolano, 2018). Stock people working with livestock should remove distractions such as, moving dangling chains, coats hung on fences, or a paper cup on the floor. Removal of distractions can improve animal movement (Grandin, 1996, 2021). Stock people who load sheep onto trucks report that removing distractions is important (Burnard et al., 2015).

Abrupt changes in the flooring surface the animals are walking on may cause them to stop (Kilgour, 1971; Hutson, 1981). Common problems observed by the author are changing from a dirt surface to a concrete surface. A simple method to improve movement is to sprinkle dirt on the junction between the two different type of surfaces. This reduces the visual contrast between the two different surfaces. Another common flooring change is moving from a concrete floor to a metal floor in single animal scales, hoof trimming tables or stun boxes. When approaching cattle, pigs or sheep stop at either a shadow or a change in flooring, the leader will often stop and put its head down. Ron Gill at Texas A and M explains that handlers should wait for the animal to raise its head up before attempting to move the animals forward.

Animals can definitely perceive depth (Lemmon and Patterson, 1964). Since they have wide panoramic vision, it is likely that the reason they stop and put their heads down to look at a shadow or change of flooring is due to poor depth perception. In handling facilities that are raised above the floor, cattle will balk and refuse to move if they perceive the visual cliff effect Cattle were more willing to enter a center track conveyor restrainer in an abattoir when a false floor was installed to prevent them from seeing a 2 meter drop under the conveyor (Grandin, 2001). In sheep facilities where sheep are moved over a raised floor they can see through, adjustment of lighting and the direction of the grating will prevent the sheep form seeing the visual cliff effect (Hutson, 1981). If the grating is made from wood slats, the sheep are more likely to move easily if they walk across the slats (Hutson, 1981). Hutson (1981) also suggests closing up the side walls of an elevated shearing shed to prevent sheep form seeing light shining up from under the floor.

People often ask the author why livestock that had previously moved through a race or alley easily are now stopping and refusing to move. It is usually due to something that has changed that people did not notice. The author observed that at the experiment station at Colorado State University, that the cattle started stopping and refusing to move through the single file race. The cause of the problem was a new shiny highly reflective fuel tank that had been installed near the race. On a sunny day, there was a big reflection on the top of the tank. Vehicles parked alongside a race or livestock scale may also make animals balk and stop. Some scientists may dismiss these observations as anecdotal so the author decided to have her student conduct an experiment to determine how an animal may perceive a change in a previously familiar environment. People who ride horses will often say that the horse spooked and threw the rider for no reason. Spooking occurs when a horse suddenly and unexpectedly has a fear reaction that throws the rider (Carmargo et al., 2018). It is a major cause of horse accidents (Carmargo et al., 2018). It is likely that there was a change in the environment that the rider did not notice Corgan et al. (2021) habituated young colts and fillies that were trained to lead to a children's plastic playset. It was brightly colored and had a small swing and slide for a toddler each horse was walked by the playset 15 times until there was no reaction. The behaviors that were measured were stopping, quickly raising up the head, and nostrils flaring. When the playset was turned 90°, the horses reacted as if it was something new. This study was conducted with the horses walking because it would have been dangerous at higher speeds. Hawson et al. (2010) reported that danger to a rider increases when horses are ridden at faster speeds. The shape of the child's slide was totally different when the toy was rotated. Animals can be easily habituated to a novel object. Monk et al. (2018) reported that when a novel traffic cone was first placed next to the entrance of a race, it made it more difficult to move cattle into the race. After multiple trips through the race, the heifers acclimated to the traffic cone.

When cattle, pigs or other livestock refuse to move, through a handling system, people are more likely to resort to using more aversive methods for moving them (Hultgren et al., 2020; Willson et al., 2021). Some examples of aversive methods are tail twisting and beating. Grandin (2021) found that in an indoor facility, adding a light at the entrance of a race reduced electric prod use in pigs from 38% to 4%. In cattle, illuminating the entrance of a conveyor restrainer also reduced the percentage of cattle that vocalized due to electric prod use. The percentage of cattle that vocalized during handling were reduced from 8% to 0% (Grandin, 2001). In this situation, the stock people had been specifically trained to only use the electric prod on cattle that had stopped moving. Training stock people in the basic behavioral principles of cattle handling will improve handling (Ceballos et al., 2018). The three most common mistakes people make when they handle cattle is putting too many animals in the crowd pen that leads to the single file race, making excessive noise, and standing in front of an animal when attempting to move it forward (Yost et al., 2020). Another factor that can increase stress is the use of dogs at slaughter houses. The use of dogs to move sheep through races and stockyards increased stress (Sutherland et al., 2016; Starling et al., 2021).

An animal's willingness to move through a race or up a truck loading ramp is also influenced by its previous experiences. The problems caused by distractions, shadows, or noise are more likely to cause livestock to stop the first time they move through a new unfamiliar handling facility. Lewis et al. (2008) found that the heart rate was lower in pigs which were trained to move through alleys and ramps compared to the novelty of their first movement through the system. Pigs that have had regular experiences with being moved in the alleys will be easier to move in the future and less stressed by handling (Abbott et al., 1997; Geverink et al., 1998). Pigs that have become accustomed to having people walking through the fattening pens on the farm will often be easier to move at the abattoir. They have learned that when a person quietly walks through them they should get up and quietly move away (Grandin, 2021).

The author has observed at dairies that a new heifer may balk and refuse to walk over either a sunbeam or a drain. An experienced cow will usually walk over it. Animals can be easily trained to move through handling facilities. Hutson (1985) and Paranhos de Costa et al. (2020) both report that providing feed rewards will facilitate movement of sheep and cattle through corrals and races. Research has also clearly shown that sheep, pigs, and other livestock can be easily trained to enter restraint devices for veterinary examinations, injections, and other procedures (Grandin, 1989; Fonseca et al., 2019; Lomb et al., 2021). Animals that are fully acclimated will have very low levels of physiological indicators of stress. Phillips et al. (1998) reported that Bongo antelope could be trained to voluntarily enter a box for blood sampling. They were rewarded with a favorite food.

Another factor the author has observed is that the methods for moving animals on the farm or ranch can have an effect on how they react when they are handled in a new place (Grandin, 2008). Extensively raised cattle that have been exclusively handled by riders on horseback may be more difficult and dangerous to move when they first see people walking on the ground, the horse and rider may be perceived as familiar and safe and people on the ground are novel and may be frightening. They may react to the novel person with an increased size of their flight zone. The cattle may allow the familiar horse and rider to approach much closer to them, compared to a person walking on the ground. This can be especially dangerous if the cattle are taken to an auction or slaughter plant where the cattle are handled by stock people walking. Leiner and Fendt (2011) reported that training a horse to tolerate a blue and white umbrella suddenly opening does reduce the startle reaction to a flapping canvas. Both this experiment and the research with the rotates child's playset indicate that the perception of horses is visually specific. It is likely that this is also true for cattle and other livestock. A person on a horse and a person walking on the ground look completely different.