Effects of warm climatic periods on dairy cow behaviour and production in Scotland

Global warming is resulting in an overall increase in temperatures and in the frequency of extreme weather events. In dairy cattle, thresholds within the temperature-humidity index (THI) have been used to indicate points at which cattle will likely experience thermal stress (e.g., a THI threshold of 75 predicts thermal stress). However, high-yielding dairy cows that reside in temperate maritime climates may experience some degree of thermal discomfort below this threshold particularly when they are housed. Housing often results in high levels of humidity. The use of technology such as activity monitors and automated intake measures allow us to monitor responses. The aim of this study was to use technological solutions to assess behavioural changes in response to moderate increases in THI levels. Data from dairy cattle on an experimental unit were used. Data on daily lying times, lying bout frequency, step count, feed and water intake and milk yield were extracted for 8 pairs of warmer (THI<65) and 8 matching cooler (THI=43 to 60) periods. Warm and cool periods were no more than 5 weeks apart to ensure that the data from the same animals were being compared. The first three days from each period were analysed. Results showed that total daily lying time was shorter during warmer periods than cooler periods (P<0.05; means and SEMs (h): warm: 11.3±0.06h; cool: 11.8±0.06h). However, there was no effect of THI level on the no. of steps taken by cows (P>0.05 (counts) warm: 868±8 steps; cool: 878±9 steps). Water intake was higher during warm periods (P<0.05: (l) = warm: 81.2±0.7l; cool: 72.1±0.6), but there was no difference in feed intake (warm: 57.6±0.5kg; cool: 57.1±0.3kg). Milk yield was lower during warm periods than cool periods (P<0.05; (l): warm: 31.8±0.3; cool: 32.7±0.2). This suggests that behaviour and milk yield are mildly adversely affected even in conditions that are not traditionally regarded as exceeding cows’ ability to cope with thermal challenge

Effects of warm climatic periods on dairy cow behaviour and production in Scotland

Global warming is resulting in an overall increase in temperatures and in the frequency of extreme weather events. In dairy cattle, thresholds within the temperature-humidity index (THI) have been used to indicate points at which cattle will likely experience thermal stress (e.g., a THI threshold of 75 predicts thermal stress). However, high-yielding dairy cows that reside in temperate maritime climates may experience some degree of thermal discomfort below this threshold particularly when they are housed. Housing often results in high levels of humidity. The use of technology such as activity monitors and automated intake measures allow us to monitor responses. The aim of this study was to use technological solutions to assess behavioural changes in response to moderate increases in THI levels. Data from dairy cattle on an experimental unit were used. Data on daily lying times, lying bout frequency, step count, feed and water intake and milk yield were extracted for 8 pairs of warmer (THI<65) and 8 matching cooler (THI=43 to 60) periods. Warm and cool periods were no more than 5 weeks apart to ensure that the data from the same animals were being compared. The first three days from each period were analysed. Results showed that total daily lying time was shorter during warmer periods than cooler periods (P<0.05; means and SEMs (h): warm: 11.3±0.06h; cool: 11.8±0.06h). However, there was no effect of THI level on the no. of steps taken by cows (P>0.05 (counts) warm: 868±8 steps; cool: 878±9 steps). Water intake was higher during warm periods (P<0.05: (l) = warm: 81.2±0.7l; cool: 72.1±0.6), but there was no difference in feed intake (warm: 57.6±0.5kg; cool: 57.1±0.3kg). Milk yield was lower during warm periods than cool periods (P<0.05; (l): warm: 31.8±0.3; cool: 32.7±0.2). This suggests that behaviour and milk yield are mildly adversely affected even in conditions that are not traditionally regarded as exceeding cows’ ability to cope with thermal challenge

Dairy cows value an open area for lying down

As dairy cows are being housed for longer periods, with all-year-round housing growing in popularity, it is important to ensure housed environments are meeting the needs of cows. Dairy cows are motivated to access open lying areas, although previous motivation studies on this topic have confounded surface type and location (i.e. pasture outdoors vs cubicles indoors). This study measured cow motivation for lying down on an indoor open mattress (MAT; 9 m x 5 m) compared to indoor mattress-bedded cubicles, thus removing the confounding factor of surface type and location. This was repeated for an identically sized indoor deep-bedded straw yard (ST), to investigate whether surface type affected motivation for an open lying area. Thirty Holstein-Friesian dairy cows were housed in groups of 5 (n = 5 x 6) in an indoor robotic milking unit with access to six mattress-bedded cubicles. To assess motivation, cows were required to walk increasing distances via a one-way indoor raceway to access the open lying areas: Short (34.5 m), followed by Medium (80.5 m) and Long (126.5 m). Cows could choose to walk the raceway, leading to the MAT or ST, to lie down or they could lie down on the cubicles for ‘free’. Overall, cows lay down for longer on the open lying areas at each distance compared to the cubicles, with cows lying down slightly longer on ST than MAT, although lying times on the open lying areas did decrease at the Long distance. However, cows were still lying for >60% of their lying time on the open lying areas at the Long distance. This study demonstrates that cows had a high motivation for an open lying area, the provision of which could better cater for the behavioural needs of housed dairy cows and improve housed dairy cow welfare

Quantification of the effect of in-utero events on lifetime resilience in dairy cows

Currently, the dairy industry is facing many challenges that could affect its sustainability, including climate change and public perception of the industry. As a result, interest is increasing in the concept of identifying resilient animals, those with a long productive lifespan, good reproductive performance and milk yield. There is much evidence that events in utero, i.e., the Developmental Origins of Health and Disease (DOHaD), alter life-course health of offspring and we hypothesized that these could alter resilience in calves, where resilience is identified using lifetime data. The aim of this study was to quantify lifetime resilience scores (LRS) using an existing scoring system based on longevity with secondary corrections for age at first calving and calving interval and to quantify the effects of in-utero events on the LRS using 2 data sets. The first was a large data set of cattle in 83 farms in Great Britain born from 2006 to 2015 and the second was a smaller, more granular data set of cattle born between 2003 and 2015 in the Langhill research herd at Scotland's Rural College. Events during dam's pregnancy included health events (lameness, mastitis, use of an antibiotic or anti-inflammatory medication), the impact of heat stress as measured by temperature-humidity index and perturbations in milk yield and quality (somatic cell count, percentage fat, percentage protein and fat:protein ratio). Daughters born to dams that experienced higher temperature-humidity indexes while they were in-utero during the first and third trimesters of pregnancy had lower LRS. Daughter LRS scores were also lower where milk yields or median fat percentages in the first trimester were low, and when milk yields were high in the third trimester. Dam LRS was positively associated with LRS of their offspring, however, as parity of the dam increased, LRS of their calves decreased. Similarly, in the Langhill herd, dams of a higher parity produced calves with lower LRS. Additionally, dams which recorded a high max locomotion score in the third trimester of pregnancy were negatively associated with lower calf LRS in the Langhill herd. Our results suggest that events that occur during pregnancy have lifelong consequences for the calf's lifetime performance. However, experience of higher temperature-humidity indexes, higher dam LRS scores and mothers in higher parities explained a relatively small proportion of variation in offspring LRS, which suggests that other factors play a substantial role in determining calf LRS scores. While 'big data' can contain a considerable amount of noise, similar findings between the 2 data sets indicate it is likely these findings are real.</p