Recipient Organization
MISSISSIPPI STATE UNIV
(N/A)
MISSISSIPPI STATE,MS 39762
Performing Department
Animal & Dairy Science
Non Technical Summary
Heat stress has an important economic impact on the dairy industry. Particularly applying to this project group, heat stress can increase mastitis risk and incidence so preventing heat stress can help prevent mastitis. Producers suffer an annual loss of $900 million due toinefficient heat abatement and decreased milk yield (St-Pierre et al., 2003). A substantial amount of research has been focusedon improved heat abatement techniques for confinement-based dairy systems, but minimal research has been performed onhow to effectively cool cattle on pasture-based dairies. Pasture-based systems are gaining popularity (USDA, 2016), particularlyin the southeastern United States because of readily available land and water coupled with the long growing season. Mississippiis home to these dairy systems and producers are seeking ways to abate heat and thus decrease economic losses.Potential benefits associated with housing dairy cows on pasture are improved udder health, reduced lameness (White et al.,2002; Hernandez-Mendo et al., 2007), and ample space to perform more natural behaviors. Dairy cows start to experience heatstress at a temperature humidity index (THI) (Collier et al., 2012). Cows housed on pasture are especially susceptible to heatstress because they are completely open to the elements. Many studies have demonstrated that as the THI increases, cowsexperience an increased body temperature and respiration rate (Kendall et al., 2007), decreased milk yield, and lower milkcomponents (Rhoads et al., 2009; Igono et al., 1992; Ray et al., 1992; Fuquay, 1981; Maust et al., 1972; Moody et al., 1967;Regan and Richardson, 1938).Industry representatives advise confinement producers to employ good ventilation as well as fans and sprinklers along the feedalley to cool cows. The use of fans and sprinklers in the holding pen can reduce body temperature for up to 2 to 4 hours aftermilking compared to cows who received no cooling at the parlor. With effective heat abatement strategies, the welfare andcomfort of dairy cows can be improved (Kendall et al., 2007). So with some ingenuity, why can't pasture based dairy producersalso utilize a similar system? Appropriate heat abatement strategies can reduce the economic impact of heat stress for dairyproducers and improve animal welfare. However, understanding cow behavior and preference surrounding pasture-based heatabatement strategies is an important factor in what recommendations should be in place.
Animal Health Component
80%
Research Effort Categories
Basic
(N/A)
Applied
80%
Developmental
20%
Goals / Objectives
Assess and apply new technologies that advance mastitis control, milk quality and/or dairy food safety (CT, KT, LA, MI, MN, MO, NY, PA, UT, VA, WA).
Identify and apply new strategies associated with the control of mastitis that can reduce the use of antibiotics in dairy herds (CT, ID, ME, MN, MO, NJ, TN, UT, VA, VT, WA, Canada).
Project Methods
The objective of this study is to evaluate dairy cattle preference between two heat abatement strategies; the industry standardpasture heat abatement technique of 80% protective portable shade cloth; and another more innovative option created by theteam here at MSU, a portable misting system. Past research by this team has shown misters to be more beneficial bothphysiologically and from a production standpoint compared to shade. However, many producers will have at least shade trees intheir pastures so the addition of portable misters may not reach its full potential if cattle choose shade over the misters eventhough the misters help abate more heat.Four, 2-acre pastures will be utilized on a plot of land already available for pasturing dairy cattle (Figure 1). Two pastures willhave portable shade and two pastures will have portable misters (Figures 2 and 3). In the first replicate, 4 groups of 6 cowseach will be randomly assigned to the 4 test pens. Each group will be initially tested in a 7-day no-choice phase; the first 4 daysallow study cows to habituate to the pen, and behaviors will be recorded for the last 3 days. Groups will then be switched to thealternate treatment (in an adjacent pen) for a second 7-day period with behaviors again recorded during the last 3 days. Duringthe choice phase, adjacent pens (one shade and one mister) will be merged to create 2 four-acre pastures with 12 cows ineach, allowing free access to the two treatments. The choice phase will also last 7 days, with behavior being recorded duringthe last 3 days. Once this replicate is completed, the treatments will be reversed (i.e., the shade pens will become mister pensand vice versa) and 4 new groups of 6 cows each will be assigned to the 4 test pens and tested in the no-choice phase. Afterthat, the pens will be merged again for the choice phase replicate. At the end of the study, a total of 48 cows composed of 8 testgroups in the no-choice phase and 4 test groups in the choice phase will have been evaluated.Temperature humidity index will be recorded at 10-min intervals with a data logger on a weather station located in the pastureand will be used to measure thermal comfort of cows (Kendall et al., 2006; Kendall et al., 2007). Because it is expected to beconsistently above 68 during the study period, the misters will stay on all day every day (Zimbelman et al., 2009).Cows will be fitted with precision dairy monitoring technologies to monitor activity (lying time) and internal body temperature(Smaxtec reticulorumen bolus). Behavior measures (in/out of shade or misters and time at the feed and water troughs) will bevisually observed during the observation periods. Respiration rate will be observed for each cow at the start of every hour duringthe observation periods. Milk yields will be recorded for every milking using an automated parlor system (Dairyplan DP5,Westfalia Surge). Milk samples will be collected on day 7 of each observation period for analysis of milk components (fat, crudeprotein, lactose, SCC). Body condition scores and hygiene scores will be collected once weekly. A rising plate meter will beused to estimate the available forage in each pasture. All groups will use a path that is 2,070 ft (black line in Figure 2) to walk tothe parlor twice each day. All groups will be cooled with fans in the parlor holding pen before milking. All study cows will haveaccess to water ad libitum and will be fed the same diet, consisting of a partial mixed ration to complement what they graze. Alltreatment groups will be fed after each milking in their pens. Orts will be measured and recorded for each treatment group.