Dairy cow lying times
Adequate lying time is considered an important aspect of cow welfare. Tucker et al (2021) (Journal of Dairy Sciencehttps://doi.org/10.3168/jds.2019-18074) examined what is known about cows' motivation to lie down and the consequences for health and other indicators of biological function when this behaviour is thwarted. They review the environmental and animal-based factors that affect lying time in the context of animal welfare. Cows can be highly motivated to lie down. They show rebound lying behaviour after periods of forced standing and will sacrifice other activities, such as feeding, to lie for an adequate time. They will work, by pushing levers or weighted gates to lie. Some evidence suggests that risk of lameness is increased in environments that provide unfavourable conditions for cows to lie and where cows are forced to stand. Lameness itself can result in longer lying times, whereas mastitis reduces it. Cow-based factors such as reproductive status, age, and milk production influence lying time, but the welfare implications of these differences are unknown. This paper uses North American terminology and reports lower lying times in pasture-based systems, dry lots, and bedded packs (9 h/d) compared with tiestalls and freestalls (10 to 12 hours/day). Unfavourable conditions, including too few lying stalls, hard or wet lying surfaces, inadequate bedding, stalls that are too small or poorly designed, heat, and rain all reduce lying time. Time constraints, such as feeding or milking, influence lying time. However, the authors state that more information is needed regarding implications of mediating factors such as the effect of the standing surface (concrete, pasture, or other surfaces) and cow behaviour while standing to understand the effect of low lying times on animal welfare. Many factors contribute to the difficulty of finding a valid threshold for daily lying time to use in the assessment of animal welfare. While longer lying times often correspond with cow comfort, and shorter lying times are seen in unfavourable conditions, exceptions occur, when cows lie down because of disease or when they are standing because of oestrus or parturition, or to engage in other behaviours. To conclude, lying behaviour is important to dairy cattle, but caution is needed when drawing firm conclusions about animal welfare from measures of lying time.
In the second paper, the aim of the study by Shewbridge Carter et al (2021) (Journal of Dairy Science10.3168/jds.2020-18781) is to assess cow preference for two different qualities of lying area that appear to be important to cows, surface type and an open lying space, to better understand how to optimise lying comfort. Twenty-four Holstein dairy cows were used during the study, which consisted of six experimental periods, each lasting 21 days. Cows were tested four at a time and individually housed in their own test pen. Each pen had three lying surfaces: sand, mattress, and straw (2.4 m × 2.4 m each) with a freestall in the middle of each, which could be removed. Cows were given access to one surface at a time (training period) with a freestall for 2 days, and then given a choice of all three surfaces for 2 days. When given the choice with freestalls in position, cows spent, on average, the largest amount of their lying time on straw followed by mattress. Freestalls were then removed and the training and choice phase was repeated on the following day, with cows, on average, spending the most time lying on straw. Finally, a freestall was refitted onto each cow's most preferred surface and the cows were given a choice between lying on their most preferred surface with a freestall (P1+freestall) or on their second or third preferred surface without a freestall (P2+open and P3+open) for 3 days. During this final trade-off stage, of the 19 cows for which data were available, 14 cows chose to give up the opportunity to lie down on their most preferred surface to have more space on P2+open and P3+open, three cows chose to lie down on P1+freestall, and two cows made no clear choice. Overall, cows spent the largest amount of their total lying time on their sec- ond most preferred surface as an open lying space compared with their preferred surface with a freestall. The results indicate that when lying down, these cows valued an open lying space more than the lying surface.
COVID-19
There is strong evidence that SARS-CoV-2, the causative agent of the coronavirus disease 2019 (COVID-19) pandemic, originated from an animal reservoir. Some domestic animal species, including cats, ferrets, and minks, have been demonstrated to be susceptible to SARS-CoV-2, while others, such as pigs and chickens, are not. Importantly, the susceptibility of ruminants to SARS-CoV-2 is unknown. Teodoro et al (2021) (Veterinary Microbiology10.1016/j.vetmic.2020.108933) investigated the replication and tissue tropism of two different SARS-CoV-2 isolates in the respiratory tract of three farm animal species — cattle, sheep, and pigs — using respiratory ex vivo organ cultures. They demonstrate that the respiratory tissues of cattle and sheep, but not of pigs, sustain viral replication in vitro of both isolates. Intriguingly, a SARS-CoV-2 isolate containing an amino acid substitution at site 614 of the spike protein (mutation D614G) replicated at higher magnitude in ex vivo tissues of both ruminant species. These results suggest that additional in vivo experiments involving several ruminant species are warranted to determine their potential role in the epidemiology of this virus.