@conference {89259,
	title = {Does Production Worth and Breeding Worth reflect cow profitability?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {73},
	year = {2013},
	month = {Jan},
	pages = {17-20},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {<p>Production worth (PW) is an economic index estimating the efficiency that a cow converts feed into farm profit. Breeding worth (BW) is another economic index that estimates a cow{\textquoteright}s or sire{\textquoteright}s ability to breed profitable replacements. This study evaluates how well PW and BW are correlated with net income (NI) per 4.5 tonnes (t) of dry matter (DM) consumed on a pasture based New Zealand dairy farm. During the 2009/10 season at Massey Number 4 Dairy Farm, cow milk yield and composition were determined at monthly herd tests, and live weight data was automatically collected twice daily using a walk-over-weigh system. The results show that this herd is achieving a genetic gain of $6.74 BW per year. Correlations of 0.52 and 0.31 (P \&lt;0.001) were found between NI per 4.5 t DM and PW and BW, respectively. The NI per 4.5 t DM was higher in cows between 3- to 9-years-old than first lactation cows. The NI per 4.5 t DM was also strongly correlated with the milk, fat and protein yields (P \&lt;0.001). This study confirms that PW, rather than BW, better reflects the genetic capability of a cow to convert feed into farm profit.</p>
},
	issn = {1176-5283},
	author = {Clark BJ and Garcia-Muniz JG and Black PJ and Lopez-Villalobos N}
}
