@article {3672,
	title = {Deterministic modelling of nitrogen utilisation by horses managed under pasture-based, intensive and semi-intensive systems with different levels of pasture intake.},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {1-7},
	address = {Palmerston North},
	abstract = {There are limited data on the average nitrogen (N) intake and N loss for the different classes of equine livestock, and the different equine production systems within New Zealand.  Using a deterministic model, the total nitrogen excreted, and nitrogen partitioned into animal requirements, urine and faeces were estimated based on the crude protein requirement, digestible crude protein intake, and crude protein excreted in urine and faeces.  Separate models were generated for five different livestock classes managed within three different production systems (commercial breeding farm, sport horse and racehorse). Overall, the N in diet (\%), the modelled daily N intake and N losses varied with the percentage of pasture in the diet.  The faecal N loss remained consistent (20-25\%) across diets and horse classes whereas urinary N loss increased with daily N intake and percentage of pasture in the diet. Total N loss per day was estimated to be 0.18, 0.28, and 0.48 g N/kg body weight in racehorse, sport horse and Thoroughbred mares respectively.  The N excretion per unit weight from young horses, racehorses and sport horses were substantially lower than that reported for ruminants. Therefore, horse-specific data should be used when modelling farm-level nitrogen excretion.},
	issn = {1176-5283},
	author = {Chin YY and Back PJ and Gee EK and Rogers CW}
}
@article {3672,
	title = {Livestock and pasture management on commercial Thoroughbred breeding farms: implications for estimating nitrogen loss},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {79},
	year = {2019},
	month = {07/2019},
	pages = {65-70},
	address = {Palmerston North},
	abstract = {Published data on livestock and pasture management on Thoroughbred breeding stud farms were collated to model and estimate farm-level variables required to estimate nitrogen leaching. On commercial farms, stocking density doubled during the breeding season (August {\textendash} December). The effective stocking density increased with farm scale (number of resident mares) but decreased with farm size (total effective area). Therefore, farm nitrogen output may fluctuate seasonally and will be influenced by farm size and scale. Farm size and scale independently affected the stocking and grazing management (i.e., paddock rotation interval) for the different equine stock classes (empty, pregnant, mares with foals). Stocking and grazing management influenced the pasture available and subsequently, the grazing behaviour as determined by the difference between pasture mass of lawns and roughs. The difference between pasture mass of lawns and roughs was reduced with increasing stocking density and decreasing pasture availability, and increased under conditions of high stocking density (>2 mares/ha) and low pasture availability (<400 kg DM/ha/horse). Modification of grazing behaviour could affect the nitrogen-leaching potential by modifying the size of manure-deposition area and the N-loading rate on urine and dung patches. The complex relationship between farm, horse and management factors needs to be included when estimating nitrogen leached from equine properties.},
	issn = {1176-5283},
	author = {Chin YY and Back PJ and Gee EK and Rogers CW}
}
