Invited review: Lying time and the welfare of dairy cows

Adequate time lying down is often considered an important aspect of dairy cow welfare. We examine what is known about cows' motivation to lie down and the consequences for health and other indicators of biological function when this behavior is thwarted. We review the environmental and animal-based factors that affect lying time in the context of animal welfare. Our objective is to review the research into the time that dairy cows spend lying down and to critically examine the evidence for the link with animal welfare. Cows can be highly motivated to lie down. They show rebound lying behavior after periods of forced standing and will sacrifice other activities, such as feeding, to lie down for an adequate amount of time. They will work, by pushing levers or weighted gates, to lie down and show possible indicators of frustration when lying behavior is thwarted. Some evidence suggests that risk of lameness is increased in environments that provide unfavorable conditions for cows to lie down 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. Lower lying times are reported in pasture-based systems, dry lots, and bedded packs (9 h/d) compared with tiestalls and freestalls (10 to 12 h/d) in cross-farm research. Unfavorable conditions, including too few lying stalls for the number of cows, 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, can influence lying time. However, more information is needed about the implications of mediating factors such as the effect of the standing surface (concrete, pasture, or other surfaces) and cow behavior while standing (e.g., being restrained, walking, grazing) 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. Although higher lying times often correspond with cow comfort, and lower lying times are seen in unfavorable conditions, exceptions occur, namely when cows lie down for longer because of disease or when they spend more time standing because of estrus or parturition, or to engage in other behaviors. In conclusion, lying behavior is important to dairy cattle, but caution and a full understanding of the context and the character of the animals in question is needed before drawing firm conclusions about animal welfare from measures of lying time.     

Dairy cows use and prefer feed bunks fitted with sprinklers

Sprinklers reduce heat load in cattle, but elicit variable behavioral responses: cows readily use water in some studies, but in others either avoid it or show no preference. Nevertheless, on US dairies, a common way to cool cows is with nozzles mounted over the feed bunk that intermittently spray (i.e., 5 min on, 10 min off, as in this study) animals’ backs while they feed. The objectives of this study were to determine how this type of sprinkler system affects behavior (single-treatment phase), and to assess preferences when cows were allowed to choose between feed bunks with or without sprinklers (choice phase). Data were collected 24 h/d for lactating Holsteins tested in groups of 3 cows (n = 8 groups) in warm ambient conditions [air temperature (mean ± standard deviation): 24-h average = 24.5 ± 2.5°C, maximum = 36.0 ± 3.5°C]. In the single-treatment phase, cows were fed from shaded bunks with or without sprinklers for 2 d/treatment, with order of exposure balanced in a crossover design. When sprinklers were present, cows spent more time at the bunk, both feeding [sprinkler vs. no sprinkler: 3.5 vs. 2.5 h/24 h, standard error (SE) = 0.12 h] and standing without feeding (4.3 vs. 2.3 h/24 h, SE = 0.32 h) than when no sprinklers were present. Sprinklers lowered the average 24-h core temperature (38.8 vs. 39.2°C, SE = 0.08°C), particularly on warmer days. Water cooling also mitigated the effects of weather on feeding time, which decreased with increasing heat load (air temperature and temperature-humidity index) when cows did not have sprinklers, but was unchanged when sprinklers were provided. In the choice phase, feed was provided ad libitum in both treatments for 5 d and preference was assessed. All groups preferred the feed bunk with sprinklers (78 vs. 22% of time spent near both feed bunks, SE = 3.9%), and the magnitude of this preference increased linearly with heat load. In both phases of the study, cows protected their heads from direct spray when head position was elective (i.e., standing without feeding): cows were more likely to put their heads through the head gates when the sprinklers were on than off (single-treatment phase: 78 vs. 59%, respectively, of time spent standing without feeding, SE = 2.8%; choice phase: 71 vs. 52%, SE = 2.0%). In conclusion, although cows avoided wetting their heads, this is the first study to demonstrate that cattle readily use and clearly prefer sprinklers mounted above the feed bunk, possibly due to the cooling provided by this resource.     

Stepping behavior and muscle activity of dairy cattle standing on concrete or rubber flooring for 1 or 3 hours

The type of flooring in dairy cattle systems influences cows' health and welfare. Although concrete is common, the use of more compressible flooring, such as rubber, is increasing. Cows prefer to stand and walk on rubber surfaces than on concrete; however, it is largely unknown how walking and standing for longer periods of time influence muscle activity and fatigue. Therefore, we used measures of behavior and muscle activity to investigate the potential benefits of providing a rubber flooring surface to dairy cattle. Sixteen lactating Holstein cows were forced to stand on either concrete or rubber flooring for 1 or 3 h in a 2 × 2 crossover design. Surface electromyograms (SEMG) and skin surface temperature were used to evaluate muscle activity, fatigue, and movement of muscle activity between the hind legs. Activity of 2 muscles, the bicep femoris and middle gluteal, was assessed during both static contractions, when cows transferred weight to each hind leg, before and after 1 and 3 h of standing, and dynamic contractions, associated with steps and with shifts in weight without steps. In addition, we evaluated stepping rate, time between each step, feeding behavior, skin surface temperature, and latency to lie down after standing. Standing duration influenced both the behavior and muscle activity of cows. Stepping rate increased with standing time for cows on both flooring types. Static muscle activity parameters of the bicep femoris muscle were higher after 3 h of standing for cows standing on both flooring types (2.3 and 3.6% increases in median amplitude and median power frequency, respectively) compared with the change after 1 h and compared with baseline values before the standing treatment. Flooring type influenced the behavior and muscle activity of the cows, particularly during the first hour of exposure; cows standing on rubber had a higher stepping rate, shorter interval between steps, and higher number of SEMG shifts (muscle activity shifts with or without visible steps) than cows on concrete. There was no difference in skin surface temperature, feeding behavior, or latency to lie down between the treatments. The results show that standing on a rubber flooring caused a different initial behavioral response compared with standing on concrete; however, possible reasons for these changes are unclear. Standing for 3 h resulted in an increase in stepping rate and in some muscle activity parameters; however, the results regarding muscle fatigue in relation to flooring type are inconclusive.     

An easy method to monitor lactide polymerization with a boron fluorescent probe

Fluorescence spectroscopy has been widely used to monitor different polymer processes such as polymerization kinetics, chain entanglements, and thermal transitions. The solvent-free controlled ring-opening polymerization (ROP) of lactide is significant both commercially and for research; thus, monitoring this process with a simple fluorescence method can be very useful. Here, a fluorescent dye, difluoroboron 4-methoxydibenzoylmethane (BF(2)dbmOMe) is employed to probe lactide bulk ROP by measuring the emission from solidified reaction aliquots at room temperature. It was found that, through the course of polymerization, the fluorescence of BF(2)dbmOMe in the solid-state aliquots exhibited a systematic shift from yellow to green and then to blue, accompanied by a gradual reduction in the decay lifetime. The fluorescence color change is sensitive to the monomer percent conversion, not the polymer molecular weight. On the basis of these observations and experimental data, we propose that the long-wavelength emission with perceivably longer lifetimes arises from BF(2)dbmOMe dye aggregates (ground and/or excited states), while the dissolved individual dye molecules are responsible for the blue fluorescence with a shorter lifetime. This demonstration of the utility of BF(2)dbmOMe as a fluorescent probe for lactide polymerization could have important practical implications.     

Development and Evaluation of a Bayesian Low-Vision Navigation Aid

Way finding in unfamiliar environments can pose a challenge to anyone but can be particularly challenging to someone who has some sort of visual loss. In this paper, we describe an indoor navigation aid that uses Bayesian statistics to localize and guide an individual from an unspecified location within a building to a specific destination. We also present three studies investigating the efficacy of this system as a low-vision navigation aid. Two studies were conducted in virtual indoor buildings using desktop virtual reality (VR) and one study was conducted in a real building. All three studies investigated navigation performance with versus without the navigation aid. In all three studies, subjects traveled a shorter distance with the navigation aid than without it. In the VR studies, the navigation aid actually improved performance over navigating with normal vision.     

I Am What I See: How Avatar and Opponent Agent Body Size Affects Physical Activity Among Men Playing Exergames

This study examined how avatar body size (normal, obese) and opponent character body size (normal, obese) influenced physical activity while male participants played an exergame. Males operating normal weight avatars showed more physical activity than those using obese avatars. Perceived avatar and opponent character body‐size differences moderated the effect of avatar appearance on physical activity. Participants showed decreased physical activity when the opponent character was perceived as slightly more obese than their avatar. Participants also showed decreased physical activity when their avatar was perceived as more obese than the opponent character. We discuss theoretical implications and applications of using virtual characters to increase gamers' physical activity. These findings are also compared to an earlier study with an all‐female sample.     

Gene disruption in Schizosaccharomyces pombe using a temperature‐sensitive Ura4p

We have generated a temperature‐sensitive form of the Ura4p protein from the fission yeast Schizosaccharomyces pombe. A single T‐to‐C mutation at nucleotide 782 (relative to the initiator ATG codon of ura4) changes the leucine residue at position 261 in Ura4p to a proline. The mutant Ura4p^ts supports growth at 30°C but is unable to allow growth at 37°C in the absence of uracil when a single copy of the gene is integrated into the host chromosome. Using the ura4^ts cassette for gene replacements simplifies the identification of transformants in which the disruption construct has undergone homologous integration into the host chromosome, as these individuals contain a single copy of the ura4^ts gene and fail to grow when replicated to 37°C in the absence of uracil. Copyright © 1999 John Wiley & Sons, Ltd.