Graduate Student Literature Review: The effect of housing systems on movement opportunity of dairy cows and the implications on cow health and comfort

Outdoor access practices in the Canadian dairy industry

Dairy cows are highly motivated to access pasture and have a partial preference for alternative forms of outdoor access (e.g., deep-bedded outdoor sand or wood-chip packs). In addition, Canadians value the provision of outdoor access to dairy cows as they perceive it as important for good cow welfare. In contrast to Europe, Oceania, and the United States, little data exist on the use of outdoor access on Canadian dairy farms. Therefore, our objective was to assess current outdoor access practices for dairy cows in Canada. An online questionnaire was used to determine housing and outdoor access practices for lactating cows, dry cows, pregnant heifers, and weaned, nonpregnant heifers on Canadian dairy farms. The questionnaire was distributed by the 10 provincial milk boards between November 2020 and August 2021, resulting in an 8.9% response rate (n = 903 completed questionnaires). In total, 75% (n = 675) of respondents provided some form of outdoor access to at least 1 cattle class on their farm. Pasture was the most frequently used form of outdoor access for all cattle classes. Based on a weighted average, a total of 29% and 48% of Canadian dairy farms provided lactating and dry cows, respectively, access to pasture; for youngstock, these numbers were 48% and 27% for pregnant heifers and weaned, nonpregnant heifers, respectively. Herd size (for each cow class), indoor housing system, and region were all associated with the provision of pasture. Farms with larger lactating herds less often provided access to pasture; larger herd sizes in terms of weaned, nonpregnant heifers, pregnant heifers, and dry cows were also associated with a lower likelihood of access to pasture. Farms using indoor bedded pack housing for their lactating cows more often provided pasture to this cattle class than farms with freestall or tiestall housing; this likelihood did not differ between farms with tie or freestall housing for this cattle class. Dry cows or pregnant heifers housed in a tiestall were more often provided pasture than freestall-housed dry cows or pregnant heifers. Housing type for weaned, nonpregnant heifers was not associated with the likelihood of pasture provision. Farms in British Columbia or on Canada's East Coast (i.e., Nova Scotia, New Brunswick, and Prince Edward Island) more often provided lactating cows pasture compared with farms in other regions. For the other 3 cattle classes, farms on the East Coast of Canada more often provided pasture than farms in other parts of Canada. These results will inform future decisions regarding outdoor access for Canadian dairy cattle and may also aid in identifying future areas of research. For example, our results may aid in designing housing systems that facilitate outdoor access in larger herds and in areas that are subject to more extreme weather conditions.

Research and application of a new multilevel fuzzy comprehensive evaluation method for cold stress in dairy cows

Effective and comprehensive evaluation of cold stress is critical for healthy dairy cow breeding in the winter. Previous studies on dairy cow cold stress have considered thermal environmental factors but not physiological factors or air quality. Therefore, this study aimed to propose a multilevel fuzzy comprehensive evaluation (FCE) method for cold stress in dairy cows based on the analytic hierarchy process (AHP) and a genetic algorithm (GA). First, the AHP was used to construct an evaluation index system for cold stress in dairy cows from 3 dimensions: thermal environment (temperature, relative humidity, wind speed, and illumination), physiological factors (respiratory rate, body surface temperature), and air quality [NH₃, CO₂, inhalable particulate matter (PM₁₀)]. Second, the consistency test of the judgment matrix was transformed into a nonlinear constrained optimization problem and solved using the GA. Next, based on fuzzy set theory, the comment set and membership function were established to classify the degree of cold stress into 5 levels: none, mild, moderate, high, and extreme. Then, the degree of cold stress in cows was obtained using multilevel fuzzy comprehensive judgment. To investigate the effect of illumination indicators on cold stress in dairy cows, 24 prelactation cows from the south and north sides were selected for a 117-d comprehensive cold stress evaluation. The results showed that the mean mild cold stress durations were 605.3 h (25.22 d) and 725.5 h (30.23 d) and the moderate cold stress durations were 67.2 h (2.8 d) and 96 h (4.0 d) on the south and north sides, respectively. Simultaneously, generalized linear mixed model showed that there were significant correlations between the daily cold stress duration and milk yield, feeding time, lying time, and active steps in the cows on both sides. This method can reasonably indicate cow cold stress conditions and better guide cold protection practices in actual production.

Effects of free-choice pasture access on lameness recovery and behavior of lame dairy cattle

Lameness is a common condition in dairy cows. Free-choice access to pasture may benefit lame cows by providing a softer and more comfortable lying and standing surface; however, the effects of this system on lameness have not yet been explored. We evaluated whether a 7-wk period of free-choice pasture access would improve lameness recovery and affect the lying behavior of lame dairy cows. Lactating Holstein cows, all clinically lame upon enrollment and housed inside a freestall barn, were pseudo-randomly allocated to 1 of 2 treatments (balancing for gait score, parity, and previous lameness history): free-choice access to pasture (n = 27; pasture) or indoor housing only (n = 27; indoor). Cows were gait scored weekly by an observer blind to treatment, using a 5-point numerical rating system (NRS 1 = sound, NRS 5 = severely lame), and hoof inspections were performed by professional trimmers at the start and end of the 7-wk period. Lying behavior was assessed using accelerometers. Cows were categorized as either having a sound period (NRS <2 over 2 consecutive weeks) or remaining lame. Cows spent, on average, 14.8 ± 10.0% (mean ± SD) of their total time on pasture, with much of this time spent outside at night. Over the 7-wk period, 42% of cows had at least one sound period (pasture: 55.6%, indoor: 26.9%), but this was more likely for cows with pasture access (odds ratio = 4.1; 95% confidence interval: 1.1-14.6%). Pasture cows also spent more total weeks sound compared with indoor cows (2.0 ± 0.34 vs. 0.81 ± 0.35 wk). Cows with pasture access lay down for less overall time than indoor cows (13.9 ± 0.29 vs. 12.7 ± 0.28 h/d) and spent more time standing on pasture (74%) than when indoors (47%). These results suggest that lame dairy cows will use pasture when provided with free-choice access, primarily at night, and that access to pasture aids in lameness recovery. We encourage future research to investigate longer-term effects on the recovery of hoof lesions and reoccurrence of lameness cases.