@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}
}
@conference {89233,
	title = {Spatial-time correlation between milk urea with milk components and somatic cell score of bulk milk samples from farms supplying milk for cheese and milk powder manufacturing},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {73},
	year = {2013},
	month = {Jan},
	pages = {108-113},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {<p>Milk urea nitrogen (MUN) has been used to indicate the dietary protein/energy balance for the dairy cow, and may be negatively associated with the content of valuable milk components for the manufacture of dairy products. The objective of the study was to model the temporal pattern of the correlation between MUN and the percentages of fat (FP), protein (PP), lactose (LP) and total milk solids (MSP), and somatic cell score (SCS) (log2somatic cell count) of bulk milk samples from farms supplying milk for the manufacture of cheese and milk powder. Daily records of milk delivery dates, the composition of bulk milk samples for FP, PP, LP, MSP, SCS and MUN from 28 seasonal supply dairy farms were analysed. The results show there is a negative association between MUN and milk components. The concentration of MUN in milk of New Zealand cows is high compared with that of milk from cows fed a total-mixed-ration, due to the high crude protein content in the pasture fed to dairy cows in New Zealand.</p>
},
	issn = {1176-5283},
	author = {Garcia-Muniz JG and Lopez-Villalobos N and Burken JL and Sandbrok T and Vazquez-Pelaez CG}
}
@conference {40990,
	title = {Growth curves and productivity of Holstein-Friesian cows bred for heavy or light mature live weight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {68-72},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {This paper presents data for live weights (LW) from birth to maturity, and for yields of milk and milksolids (MSY) per lactation, from two lines of Holstein-Friesian cows bred for heavy (H) or light (L) mature LW. Compared with the Brody, Gompertz and Logistic functions, the Von Bertalanffy function provided the best fit to the LW data, and prediction from this function has been used in the following analyses. The breeding values (BV) for LW of the sires (H: 86.3 kg; L: 31.0 kg) and maternal grandsires (MGS) (H: 55 kg; L: 38 kg) used to develop the H and L LW lines were higher (P<0.001) for the H line than for the L line, and they were significantly associated with the actual birth weight (H: 41 kg; L: 35 kg) and mature live weight (H: 520 kg; L: 467 kg) of the cows. The heavy sires also had significantly higher BV for yield of milk (H: 1037 l; L: 737 l), milkfat (H: 33.0 kg; L: 27.5 kg), and milk protein (H: 31 kg; L: 22 kg), and the H cows produced more milk (H: 4708 l; L: 4323 l), and MSY (H: 364 kg; L: 348 kg) than the L cows. However, L sires had slightly higher (P = 0.07) value for Breeding Worth than the H sires (H:37; L:46), and there were only small differences in yields of milk or MSY between the two lines when these were expressed per kg of LW, per kg of LW0.75 or per tonne of dry matter required (H: 84 kg MSY/tonne DM; L: 87 kg MSY/tonne DM). The results indicate that the extra MSY by the H cows (+ 16 kg) almost compensated for the effect of their extra LW (+ 46 kg), so that the H cows were only slightly less efficient than the L cows, as predicted by their respective sire{\textquoteright}s Breeding Worth. },
	issn = {1176-5283},
	author = {Garcia-Muniz JG and Holmes CW and Garrick DJ and Lopez-Villalobos N and Wickham BW and Wilson G and Brookes IM and Purchas RW}
}
@conference {41008,
	title = {Herbage intake, grazing behaviour and feed conversion efficiency of lactating Holstein-Friesian cows that differ genetically for liveweight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {128-131},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Two experiments were carried out to compare the feed conversion efficiency at high pasture allowances in early (EXP1) and mid-lactation (EXP2) of genetically heavy (H) or light (L) Holstein-Friesian cows (H = 487, L = 410 kg, P<0.001). Average milksolids (MS) yield was not significantly different in EXP1 (H = 1.73, L = 1.64 kg MS), but the H line had higher MS yield than the L line in EXP2 (H = 1.70, L = 1.54 kg/cow/day, P<0.001). The mean individual dry matter intakes (DMI, kg/cow/day), measured using the n-alkanes technique, were higher for H cows in both EXP1 (H = 15.5 and L = 13.9; P<0.05) and EXP2 (H = 12.2 and L = 10.8; P<0.05). However, herbage intake was not significantly different between the H and L cows when adjusted to a common MS yield. Feed conversion efficiency (g MS/kg DMI) was slightly higher for the L cows during EXP1 (H = 114, L = 120, P = <0.1), but not different for H and L cows during EXP2 (H = 144, L = 143). The calculated bite size of the H cows was on average 0.095 g DM/bite (pooled for the two experiments) heavier (P<0.05) than that of the L cows, but the L cows showed a consistently faster rate of biting than the H cows (H = 51, L = 56 bites/min, P<0.05). Although the H cows had higher MS yield than the L cows, especially in EXP2, the higher MS yield was not associated with increased efficiency, presumably because the H cows required more energy for maintenance than the L cows. },
	issn = {1176-5283},
	author = {Laborde D and Garcia-Muniz JG and Holmes CW}
}
@conference {40991,
	title = {Reproductive performance of Holstein-Friesian cows differing genetically in live weight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {73-75},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The reproductive performance of two genetic lines of Holstein-Friesian cows bred for heavy (H) or light (L) mature live weight (LW) was evaluated from 1992 to 1997. The interval calving to ovulation was shorter (P<0.05) for H cows (28 {\textpm} 3.2 days) than for L cows (L: 31 {\textpm} 2.5 days), but the difference between the lines in the interval calving-first heat was not significant (H: 50 days; L: 43 days). However, in the cows older than 2 years old, the H cows had a lower conception rate at first service than the L cows (H: 58\% vs. L: 70\%) which extended the conception and calving pattern of the H cows. The possible reasons for those differences in the reproductive performance are discussed as topics for further research. },
	issn = {1176-5283},
	author = {Laborde D and Holmes CW and Garcia-Muniz JG and Wichtel J}
}
@conference {40884,
	title = {Growth and onset of puberty in two genetically different lines of Holstein-Friesian cows, selected for either heavy or light body weight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {46-47},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Heavier body weight affects dairy farm profitability through its effects on extra dietary energy requirements for maintenance and growth and on extra income from culled cattle; therefore it is now included in the new Animal Evaluation System used with New Zealand dairy cattle. The selection of two lines of Holstein-Friesian cattle began in 1989 using proven sires with either high (H) or low (L) estimated breeding value (EBV) for live weight (LW), but which were all of high genetic merit for milk solids yield. This paper reports on the onset of puberty and the pattern of growth from birth to first calving of heifers from these two genetic lines of cattle.},
	issn = {1176-5283},
	author = {Garcia-Muniz JG and Holmes CW and Wickham BW}
}
