## 2 Materials and Methods
### Cattle Handling  
The study was conducted on a large commercial beef enterprise in the Western Victoria River Downs Region of the Northern Territory, Australia. The property is 2480 km\({}^{2}\), and the trial paddock 33 km\({}^{2}\) (Figure 1). The area has a tropical climate, with distinct wet and dry seasons. Long-term average rainfall and temperature in the region is 800 mm of rainfall per year, with an average daily maximum temperature of 35.0 \({}^{\circ}\)C and a minimum of 21.2 \({}^{\circ}\)C [14]. Rainfall is predominantly during the wet season from December to March. Vegetation is, predominantly, lightly wooded eucalypt, dominated by tropical tall grasses such as _Mitchell grass_ (_Astrebla_ spp.) [2]; however, the paddock is heterogenous with variation in vegetation and land type.  
Animals were mustered in April 2018 with a helicopter (R-22, Robinson Helicopter Company, Torrance, CA, USA) as per regular mustering processes in the area. During the two-year trial running from April 2018 to April 2020, a total of 378 trial animals were monitored. Trial cattle from the larger mob mustered in April 2018 were processed and selected based on gestation stage as described in [PERSON] et al., 2020 [15]. Trial animals were mostly Brahman (Bos Indicus) (80%) with remaining animals being of shorthorn or composite crosses. Cows were aged between 2 and 10 years old.  
Data collected for each individual cow in the larger herd included LW and LWC, measured using a walk-over-weighing (WoW) station, which was set up at the entrance to water and configured as previously described by [PERSON] et al., 2014 [PERSON] et al. (2014). Trial cows were provided with a loose mix urea supplement from June 2018 throughout the year until mid-November and then provided with phosphorus supplementation at the onset of the wet season in November 2018. In 2019, cows were provided with loose mix urea at the onset of calving in September until December, but were not provided with phosphorus kick during the 2019-2020 wet season. The dry season urea loose mix was 36% and 32% urea for each year, respectively (Table 1; Red Range Stock Supplements (Kununurra, Western Australia, Australia), and the wet season phosphorus lick block was a custom mix of 16% phosphorus (Olsen's, Yennora, New South Wales, Australia). Animals consumed an average of 150 g per head per day during the dry season in both years and 66 g per head per day of phosphorus supplement in the wet season of 2018-2019.  
All animals were subjected to commercial conditions and treatments for the duration of the trial period, including provision of supplementation and mustering procedures. Continuous mating was practised on the trial property, with calving structured around segregation of cows according to gestation stages. Weaning of calves was generally performed twice per year, once during the April and May period and again before the wet season in September and October, depending on the time calves were born during the year. Calves were between 2 and 6 months old at weaning. In 2018, weaning was performed on the 14 October and, in 2019, weaning was conducted on the 26 November. There were 8 bulls in the trial paddock during both years, which, along with the cows, used the WoW stations to access water. In addition, there were 126 calves born mid-year in 2018 and 134 calves in 2019, born later in the year. The LW and LWC data for the present study included the presence of bulls and calves in the paddock if these were tagged at muster and not weaned. The expected calving date in 2018 for 67% of the herd was mid-August, with 27% due between June and July 2018 and the remaining cows due in May 2018. In 2019, 58% were due mid-September and the remaining cows were due to calve from October to December. Weaning percentage in both years was 70%.  
Figure 1: Satellite image of the trial paddock with water points displayed. Trial animals were able to access the dam on the northern boundary in Year 1, but not in Year 2.