@conference {4185, title = {BRIEF COMMUNICATION: Adaptation of grazing sheep to GreenFeed emission monitoring units under New Zealand ryegrass-white clover pastures}, booktitle = {Hamilton}, volume = {85}, year = {2025}, pages = {27-31}, address = {Hamilton}, abstract = {

GreenFeed (GF) emission monitoring units have been extensively used in cattle, but few studies have been conducted using sheep in pastoral grazing situations. This study aimed to investigate ewe visiting behaviour in the presence of GF units and the successful collection of methane (CH$_{4}$) measurements. Commercial sheep pellets were introduced to 156 na{\"\i}ve two-tooth Romney ewes at an allocation of 130 g/ewe/day. From those, 76 frequent pellet consumers were selected for introduction to three GF units. Out of those, 22 (28.9\%) exhibited daily visits and a good stay duration (>=2 minutes) per visit at the GF units, allowing for valid CH$_{4}$ mass flow calculations. In total, the GF units were visited an average of 42.8 {\textpm} 14.9 times daily, making 4.6 {\textpm} 1.12 visits/ewe/day by the 22 frequent users. The average duration of successful CH$_{4}$ emission measurement was 5:32 {\textpm} 3:21 minutes/visit. The calculated average total CH$_{4}$ emissions were 30.02{\textpm}5.52 g/d. The study provided valuable insights into the behavioural variability and engagement levels of ewes with GF units, along with functionality and feeding aspects of the three GF units. Further, the study highlighted key challenges in training ewes and pellet consistency, which should help improve the understanding of measurement variability to support more reliable use of GF systems in grazing settings.

}, keywords = {enteric methane, ewe behaviour, GreenFeed units, pellet standardisation, sheep}, author = {R.N.N. Weerasinghe and A.K. Almeida and D.J. Horne and L. Burkitt and P.R. Kenyon and L.M. Cranston} } @conference {4192, title = {BRIEF COMMUNICATION: Nitrogen constituents in urine spot samples from sheep grazing standard and hyper-diverse pastures}, booktitle = {Hamilton}, volume = {85}, year = {2025}, pages = {55-60}, address = {Hamilton}, abstract = {

This study investigated the effect of pasture and management system on nitrogen (N) pools related to N excretion in spot samples of urine in ewes grazing a hyper-diverse (\>18 sown plant species) versus standard (perennial ryegrass + clover) pasture, managed under either contemporary (industry best-practise) or regenerative (high residuals, longer rotation length) management over a two-year period (Mar 2023-Dec 2024). A total of 160 Romney ewes were randomly allocated to four self-contained farmlets including standard pastures with contemporary management (Std-Con), standard pastures with regenerative management (Std-Reg), diverse pastures with contemporary management (Div-Con), and diverse pastures with regenerative management (Div-Reg) treatments. Urine samples were collected seasonally over two years. Results show that estimated urine volume was significantly (P=0.05) higher in ewes on diverse pastures (Div-Con: 5.19 L/d; Div-Reg: 4.97 L/d) compared to standard pastures (Std-Con: 3.79 L/d; Std-Reg: 3.52 L/d). Total urinary N output, (Purine Derivative: Creatinine ratio (PDC index), or the ratios of N, uric acid, allantoin, and urea to creatinine were not significantly affect by treatments. However, most parameters varied significantly across sampling times (P\<0.01), indicating temporal effects related to physiological stage and seasonal variation in pasture quality. Overall, diverse pasture systems tended to support greater urine output and more consistent microbial protein supply (PDC index). Urinary metabolites were measured from a single urine spot sample collected within an existing grazing study and caution is still needed when using this method to avoid inaccuracies in estimating urinary metabolites due to variations between individual animals and studies.

}, keywords = {creatinine, grazing system, purine derivatives, regenerative management}, author = {M. Miyanda and A.K. Almeida and A. Jonker and A.D. Cartmill and N.W. Sneddon and L. Burkitt and L.M. Cranston} } @conference {4188, title = {BRIEF COMMUNICATION: The Effect of the Time of Day on Creatinine Excretion from Sheep fed Perennial Ryegrass or Plantain}, booktitle = {Hamilton}, volume = {85}, year = {2025}, pages = {41-44}, address = {Hamilton}, abstract = {

This study investigated the feeding of plantain (Plantago lanceolata L.) or perennial ryegrass (Lolium perenne L.) on creatinine excretion from sheep over the day. Eleven castrated Romney-cross male lambs were separated into two groups fed either Plantain (n=five) or Ryegrass (n=six) in an indoor metabolism trial for eight days (three-day adaptation period and five-day collection phase). Urine samples were taken from each sheep at 6am, 9am, 12pm, 3pm and 6pm over 4 days and analysed for concentration of creatinine. Mean creatinine concentration was lower (p\<0.05) for the plantain group which can largely be attributed to the diuretic effect of plantain. Forage treatment did not influence the quantity of creatinine excreted by sheep per period or per day (p\>0.05). Time of day and the interaction between forage type and time influenced the concentration and amount of creatinine in urine (p\<0.05). For both forages, the mean creatinine concentration from the 12pm-3pm period most closely approximated the daily mean creatinine concentration.

}, keywords = {Creatinine excretion, diurnal rhythm, plantain, ryegrass, sheep}, author = {H.R. Fletcher and L.M. Cranston and P.C.H. Morel and J.L. Burke and S.J. Pain and A.K. Almeida} }