@article {3672,
	title = {Simulating the intake and nitrogen excretion from cows grazing forages fertilised with increasing rates of nitrogen},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {78},
	year = {2018},
	month = {07/2018},
	pages = {141-145},
	address = {Lincoln},
	abstract = {The dry matter intake (DMI), production, and urinary nitrogen (N) excretion of dairy cows grazing forage grown under increasing
N fertiliser rates were explored using a mechanistic model of a grazing ruminant. The MINDY cow model was initialised to
represent a multiparous Holstein-Friesian dairy cow in late lactation (age 3.5 years, 212 days in milk). Simulated cows were
offered a common allowance (30 kg DM/cow/d) of chicory, plantain, lucerne, or perennial ryegrass, fertilised at rates of 0, 100,
200, 350 and 500 kg N/ha/y (0N, 100N etc.) for 20 days in March. Forage physical and chemical composition data were obtained
from a Waikato experimental field site. When N rate increased from 0{\textendash}500N, predicted DMI of cows grazing plantain and ryegrass
increased by 5.2 and 2.7 kg DM/cow/day (43 and 20\% increase), respectively, facilitated by increased sward height and mass, and
reduced herbage strength. Predicted DMI of cows grazing chicory peaked at 200N and, for cows grazing lucerne, declined with
N fertilisation. Intake of highly fertilised (>200N) chicory and lucerne diets were potentially affected by high herbage soluble N
content resulting in high predicted rumen ammonia concentrations (>18 mmol/L), reducing incentive for grazing. While predicted
milk production from cows grazing chicory, plantain and ryegrass increased, the efficiency of dietary N used for milk production
declined, with increasing N applied. Increasing N rate also increased predicted urine N concentration, and urinary N excretion
from simulated cows fed chicory, plantain, and ryegrass. This study suggests that N fertiliser rates of 200N for chicory, plantain
and ryegrass provides a balance between cow production and N excretion.},
	issn = {1176-5283},
	author = {Minnee EMK and Bryant RH and Chapman DF and Gregorini P}
}
@conference {3672,
	title = {Effect of grazing system on nitrogen partitioning in lactating dairy cows grazing irrigated pastures in Canterbury, New Zealand},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {76},
	year = {2016},
	month = {07/2016},
	pages = {94-99},
	address = {Adelaide},
	abstract = {Regulations currently being developed by Regional Councils throughout New Zealand to manage freshwater quality may require
substantial reductions in nitrate leaching from dairy farms in many regions. The objective of this study was to quantify nitrogen
intake, partitioning, and excretion in two irrigated farming systems in Canterbury, comparing different possible pathways for future
industry development. A {\textquoteleft}higher input{\textquoteright} system (HI, n = 34 cows) was characterised by a stocking rate of 5 cows per/ha, ~300
kg/ha/year fertiliser N and ~1t DM/cow/year purchased supplement fed on the milking platform. The {\textquoteleft}lower input{\textquoteright} system (LI,
n = 29 cows) used a stocking rate of 3.5 cows/ha, 150 kg/ha/year fertiliser N, and minimal purchased supplement. Urine, faeces,
plasma, and milk samples were collected for N determination at consecutive afternoon and morning milkings once per month for
four years. Estimated N intake did not differ between HI and LI (537 g N/cow/day and 557 g N/cow/day respectively, P = 0.29).
No differences were recorded for N parameters and estimated milk and urine N output/cow was not affected by farm system. When
scaled to per hectare, urinary N excretion was 33\% greater for HI compared with LI (1.1 kg/ha/day and 0.8 kg/ha/day, respectively,
P = 0.02).},
	issn = {1176-5283},
	author = {Clement AR and Dalley DE and Chapman DF and Edwards GR and Bryant RH}
}
@conference {3678,
	title = {Plants for dairy grazing systems operating under nitrate leaching limits},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {74},
	year = {2014},
	month = {06/2014},
	pages = {102-107},
	address = {Napier},
	abstract = {Regulations that place a limit on the amount of nitrate-nitrogen leaching from agricultural land are currently being developed by Regional Councils throughout New Zealand. These regulations may require substantial reductions in nitrate leaching from current typical dairy farm levels. Notions of the pasture plant {\textquoteleft}ideotype{\textquoteright}, which have previously emphasised pasture growth and the intake of digestible nutrients, should now also include characteristics which can reduce the nitrogen surplus in the animal, and, therefore, the amount of nitrogen (N) excreted in urine. Information on the critical external or internal N requirements of candidate pasture species could be used to develop hypotheses regarding future grazed forage systems; currently, there are few data available for this purpose. Recent empirical evidence indicates that diverse pastures incorporating forage herbs such as chicory and plantain can reduce total urinary N load while maintaining similar levels of herbage accumulation to ryegrass-white clover pasture. However, insufficient information is available to identify the mechanisms through which the urinary N reductions occur. This specific knowledge gap needs to be filled. In addition, more information is needed on the general nitrogen nutrition physiology of candidate pasture species for future forage systems.},
	issn = {1176-5283},
	author = {Chapman DF and Edwards GR and Pinxterhuis JB}
}
@conference {41339,
	title = {Growing grass and clover separately allows animals to sustain a high nutrient intake},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {163-166},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {White clover has high nutritive value but the proportion in mixed pasture and therefore the diet, is often low. Offering sheep ryegrass and clover growing side-by-side, for short periods, increases the proportion of clover in the diet and daily intake compared to a mixed pasture. This experiment tested whether sheep offered ryegrass and clover side-by-side could sustain a high proportion of clover in their diet and a high daily intake, compared with sheep grazing ryegrass alone, clover alone and ryegrass and white clover growing as a mixed sward. Forty-eight dry, non-pregnant Romney ewes (56 {\textpm} 1.8kg live weight) were randomly allocated to four replicates (two spatial x two temporal) of each treatment (n=3) for 12 days. Average grazing time was 292 {\textpm} 16.2 min/day and did not differ significantly among treatments. Short-term intake rate on clover (5.0 g/min) was higher than ryegrass (3.5 g/min) (P=0.02). As a result, clover dominant diets supported higher daily intake (1.36 kg/d for clover alone vs. 1.08 kg/d for ryegrass alone). Sheep sustained a diet of 70\% clover and 30\% ryegrass, showing that predominance of clover in the diet was not a result of novelty. This improved daily intake would provide significant benefit to animal production systems and can be achieved simply by growing grass and clover separately. },
	issn = {1176-5283},
	author = {Marotti DM and Cosgrove GP and Chapman DF and Parsons AJ and Egan AR and Anderson CB}
}
@conference {41366,
	title = {New opportunities to improve forage- based production systems},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {273-277},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {<p>Pasture based grazing systems in New Zealand provide many benefits such as low costs of production but there are also limitations to current high stocking rate systems. These include inconsistent quality and composition of pasture and therefore animal diet. The requirements for high production and tolerance to frequent grazing limit the number of species which can be successfully grown. The rate of productivity improvement has declined in recent years and new methods of management are needed to increase production and meet changing market requirements. Altering methods of forage presentation has been shown to improve production of milk and meat from pasture by allowing animals to achieve a high daily intake of desirable species such as clover. Further new evidence of the capacity of animals to regulate their intake toward goals other than maximizing daily dry matter intake is presented. It is argued that new opportunities for increasing grassland productivity will need to consider the behavioural responses of animals grazing pasture.</p>},
	issn = {1176-5283},
	author = {Marotti DM and Chapman DF and Cosgrove GP and Parsons AJ and Egan AR}
}
@conference {41233,
	title = {Opportunities for enhancing the delivery of novel forage attributes},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {16-19},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Allocating spatially separated forage choices to grazing animals overcomes constraints inherent in mixed pastures and   sustainably delivers the required diet composition, satisfies their desire for mixed diets, and so offers a simple way to   enhance the delivery of the benefits of current and novel forage attributes.  Sheep offered grass and clover in this way   increased daily dry matter intake by 265 g/day (25\%, P<0.05) compared with conventional pasture and sustained 60-70\%  clover in their diet.   Milk production by cows was boosted by 11\% (2.4 kg/cow/day, P<0.01).},
	issn = {1176-5283},
	author = {Cosgrove GP and Parsons AJ and Marotti DM and Rutter SM and Chapman DF}
}
