@conference {69472,
	title = {Investigation of N isotopic fractionation in dairy cows using milk samples collected at the morning and afternoon milkings},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {70},
	year = {2010},
	month = {Jun},
	pages = {65-66},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {Conversion of feed protein into milk protein is a basis of sustainable dairy production systems from both economic and environmental perspectives. This project addresses the need for rapid screening tools to support nutritional and breeding strategies to improve the efficiency of converting feed into milk protein. The approach is based on the phenomenon of N isotopic fractionation, whereby N sinks become relatively enriched or depleted in 15N, as a result of differential incorporation during various biochemical reactions. Macko et al. (1986) showed that N isotopic fractionation was related to the deamination and transamination of amino acids. Sick et al. (1997) conducted a feeding experiment with rats and found that plasma protein was enriched and plasma urea was depleted in 15N relative to the diet. Furthermore, Robbins et al},
	issn = {1176-5283},
	author = {Cheng L and Dewhurst RJ and Larkin J and Buckley F and Thackaberry C and Nicol AM and Edwards GR}
}
@conference {42051,
	title = {Genetics of residual energy intake in Irish grazing dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {68},
	year = {2008},
	month = {Jan},
	pages = {88-91},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Brisbane, Australia},
	abstract = {The objective of this study was to investigate the genetics of residual net energy intake (RNEI) in grazing Holstein-Friesian cows. RNEI was defined as net energy intake minus predicted net energy requirements using the unit{\'e} fourrag{\`e}re lait (UFL) system. Net energy intake from grass and concentrate was estimated up to four times per lactation on 1,111 lactations from 463 cows on an experimental farm in Southern Ireland. Grass dry matter intake was estimated using the n-alkane technique. Lactation curves for milk, fat, protein, lactose and live weight were modelled with splines using weekly measures. A random regression was used to estimate residual, additive genetic and permanent environmental variances for RNEI and breeding values at Day 60 for each cow. Heritability for RNEI across lactation varied from 0.05 at 30 days in milk to 0.38 at 296 days in milk. Genetic parameters for RNEI obtained in this study are in agreement with those obtained under indoor conditions. Comparative performance between cows of low and high RNEI breeding value at Day 60 agrees with results obtained in beef cattle selected for high or low residual feed intake showing similar productivity but higher feed conversion efficiency in cows selected for low residual feed intake.},
	issn = {1176-5283},
	author = {Lopez-Villalobos N and Berry DP and Horan B and Buckley F and Kennedy J and O{\textquoteright}Donovan M and Shalloo L and Dillon P}
}
