@article {3672,
	title = {Phenotypic correlations of milk urea and the efficiency of crude protein utilization with milk yield traits and cow performance in two contrasting dairy systems in New Zealand},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {78},
	year = {2018},
	month = {07/2018},
	pages = {76-81},
	address = {Lincoln},
	abstract = {The objectives of the present study were to investigate phenotypic correlations of milk urea (MU) and efficiency of crude protein
utilization (ECPU) with milk production and cow parameters in two contrasting herds. Between July 2016 and May 2017, 210
cows were milked twice daily with high supplementary feed inclusion (HS) and 258 cows were milked once daily with low
supplementary feed inclusion (LS). In early, mid and late lactation, milk samples were collected to measure MU. At every herdtest
date, ECPU was calculated as protein yield (PY) divided by crude protein intake (CPI); this last variable derived from intake
estimations of metabolizable energy requirements. Positive correlations between milk yield (MY) and both dry matter intake
(DMI) and CPI were observed in LS and HS. The ECPU only correlated positively with MY traits in LS, and there was no
correlation of CPI with MU in either herd. A moderate negative correlation of ECPU with live weight (LW) was observed in both
herds, but it was stronger in LS. By suppressing MY due to the reduced milking frequency of cows fed LS, these cows gained LW,
had higher body condition score and CPI, and lower PY, reducing the ECPU. No correlation between ECPU and MU was detected.},
	issn = {1176-5283},
	author = {CorreaLuna M and Lopez-villalobos N and AlmeidaJr GA and Donaghy DJ and Kemp PD}
}
@conference {3672,
	title = {BRIEF COMMUNICATION: Efficiency of crude protein utilization and milk urea nitrogen content in Friesian, Jersey and crossbred cows milked once daily},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {77},
	year = {2017},
	month = {06/2017},
	pages = {91-92},
	address = {Rotorua},
	abstract = {For the last two decades, the New Zealand dairy industry has intensified its milk production through the inclusion of feed supplements and the increasing use of nitrogen (N) fertilizer (Di \& Cameron 2000). Increasing N losses from these systems, mainly from urine (Li et al. 2012), can negatively impact the environment. Cow N utilization efficiency can play a role in mitigating this negative effect (Woodward et al. 2011)...},
	issn = {1176-5283},
	author = {CorreaLuna M and Lopez-Villalobos N and Donaghy DJ and Kemp PD and AlmeidaJr GA}
}
