Monitoring feeding time in ruminants is one means to quantify feed intake. In grazing cattle offered feed supplement blocks, time spent licking can provide valuable information in estimating the level of blocks being ingested. This current study aimed to 1) assess an ear-tag accelerometer's capability to identify the licking behaviour at supplement blocks in grazing cattle and 2) evaluate the performance of the ear-tag accelerometer and radio-frequency identification (RFID) system to predict the individual time spent licking. Two breed groups of Angus (n = 7) and Brahman (n = 7) beef heifers were kept in two separate yards over 28 days. Each heifer was fitted with an ear-tag containing a tri-axial accelerometer set at 12.5 Hz frequency. Feed supplement blocks were provided through an RFID-equipped automatic supplement weighing unit within each yard, with access to the unit being given daily only from 16:00 h - 20:00 h. The accelerometer classification model developed using support vector machine (SVM) algorithm could distinguish between licking and non-licking behaviours, with an accuracy, sensitivity, F1 score, Cohen's kappa coefficient, and Matthew's correlation coefficient (MCC) of 86%, 93%, 0.88, 0.70, and 0.77 for Angus and 87%, 93%, 0.89, 0.73, and 0.79 for Brahman heifers. Time spent licking predicted by accelerometers were acceptable with a mean absolute error (MAE) of 22% and 11%, modelling efficiency (MEF) of 0.81 and 0.94, concordance correlation coefficient (CCC) of 0.88 and 0.96, and a ratio of root mean square prediction error (RSR) of 0.44 and 0.25, for Angus and Brahman heifers, respectively. However, the RFID system derived predictions of time spent licking in grazing heifers were unacceptable for both breeds. Overall, the ear-tag accelerometer offers the potential to predict individual time spent licking in grazing cattle to estimate block supplement intake.

Vitamin D metabolites provide a novel method to increase the efficiency of bodily phosphorus (P) and calcium (Ca) use by increasing absorption and retention along with inducing bone remodelling and deposition. These compounds may have potential application for livestock where P demand is high and in grazing environments that are deficient in P. The non-endogenous compound 1α-hydroxyvitamin D3 (1(OH)D3) utilised in the treatment of human osteoporosis bypasses the tightly regulated step of 1α-hydroxylase in the kidney to create the active hormone form of the vitamin, 1,25α dihydroxyvitamin D3. The few available ruminant studies have shown that it has a positive effect on blood P and Ca status but studies have been restricted to intramuscular injection over a relatively short period of time (Sachs et al. 1987; Naito et al. 1987; Braithwaite 1980). It was hypothesised that dietary 1(OH)D3 supplementation would have a positive and sustained effect on plasma phosphorus concentrations over an 84-day period, utilising sheep as a model ruminant.