**1. Introduction**

In Uruguay, beef production is an important part of the economy. In 2016, beef was the main export product, and Uruguay is the 6th largest beef exporter in the world, with a US \$1000 million income [1]. Worldwide product quality is crucial for the export position, and animal welfare is part of this condition [2]. In the extensive production system used in Uruguay, which is generally welfare friendly, one of the most important stressors for cattle is the transport to the slaughterhouse [3]. These animals are not used to being handled by humans and therefore handling animals on farm, loading and unloading from vehicles, transportation, occasionally passing through livestock markets, and lairage can all affect their welfare [4]. Furthermore, the fasting during transport and stunning at the slaughter affect welfare as well. Reducing physical and emotional stress during transport and associated events can improve both carcass quality and animal welfare [5].

In 1986 welfare was defined by Broom [6] as follows: "The welfare of an individual is its state as regards its attempts to cope with its environment. This includes both the extent of failure to cope and the ease or difficulty in coping". Until the moment of transportation, most beef cattle in Uruguay is reared extensively on pasture or silvopastoral systems. In this situation an animal can adapt to conditions. The deprivation of food and water, fear, arousal, mixing of groups, physical exertion and injuries are all factors that contribute to stress during transport [7]. The inability to adapt to living conditions during transport makes transport a severe impairment in welfare [8,9]. What events contribute most to the loss of welfare, and what measures are most effective to limit this degradation, are not determined yet.

There are two ways carcass bruising influences the value of marketed beef. First, severe bruises are removed from the carcass, resulting in a loss in weight per carcass [10]. Second, the increasing public concern of beef production, the way animals are slaughtered, and the degradation of welfare documented by bruises, can influence the market, and affect total demand for beef. [11]. Economic losses to bruises vary. A study from New-Zealand from 1977 reported 5.58 kg of bruised meat removed from each carcass [12]. The average loss per carcass in Uruguay was found to be 1602 ± 212 g with a minimum of 50 g and a maximum of 4900 g [10]. Numerous studies have been conducted worldwide to assess the welfare of cattle during transport [13–16]. Physiological parameters, carcass quality and behavioral measures are used for the assessment. Most studies use carcass quality since this is the least invasive method. The physiological responses to handling and transport of different livestock production animals was also extensively documented [9]. Bruising, as an event during transport, increases cortisol, packed cell volume, lactate dehydrogenase isoenzyme and hearth rate, as well as behavior [13–17].

Studies of events that caused bruising were made through direct observations and video analysis of 52 selected cows [18]. They found that 46.1% of the bruises were inflicted during animal-facility interactions, 26.9% from human-animal interactions, and another 26.9% from animal-animal interactions. The potential bruising events occurred mostly during the lairage time (91.2%), and this was confirmed by other authors [19], who added load density and stops during transportation of the cattle as risk factors for bruises. Only bruises on the back were inflicted in the stunning box and most bruises on the pin area were inflicted during loading at the farm [19]. For several years it has been assumed that the welfare of cattle depends greatly on the attitudes and training of stockpersons and on the availability of appropriate facilities [16]. Also, extreme temperatures, below −15 ◦C or above 20 ◦C, can influence cattle during transport as well as the experience of the truck driver [13].

It has been reported that factors that were associated with a high number of bruises were bad maintenance of the truck, presence of guillotine doors, journey duration longer than 5 h, bad quality of roads, devices to move animals and the presence of horned animals [3]. The objective of the present study was to evaluate whether certain events during loading, transporting, and unloading cattle have an influence on the amount, location, and degree of bruises on the carcass.

## **2. Materials and Methods**

Over a period of 3 weeks all trucks arriving at one of the major slaughterhouses of Uruguay have been assessed on various parameters in three main subjects: loading, the journey, and unloading. The following day, all animals were assessed on the number, location, and severity of bruises on the carcass according to the method developed previously by Huertas et al. [3]. All assessments were done by four trained observers. To standardize observations in the slaughterhouse, a two-week trial period was performed, in which the inter-observer reliability was optimized. The daily routine of the slaughterhouse was as follows: Most cattle transports arrived between 5 pm and 2 am. After arrival

and administration, the truck driver would unload the cattle on a ramp. Animals were given a group number when leaving the truck. This number was related to the farm of origin. Some groups were on multiple trucks and on some trucks there was more than one group present. All groups of animals stayed together and there was no mixing between groups. From this point on the lairage period started in which animals where moved to different pens closer to the stunning box. Slaughter started at 6 a.m. with an all-in-all-out system. Information about the loading and the journey was collected with a survey from the truck drivers.

#### *2.1. Truck, Driver and Loading*

The loading of the cattle was assessed from a survey filled in by the truck drivers, asking for: Time the loading took in minutes; the course of loading specified between 'good', 'regular' and 'bad'; the use of the following devices: flags, electric cattle prods and/or sticks. Furthermore, the questionnaire was about the number of years of experience with transporting beef cattle and if an animal welfare training course was attended.
