@conference {41287,
	title = {Feed intake capacity in Holstein-Friesian cows which differed genetically for body weight},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {207-209},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The feed intake capacity (FIC) of pregnant, non-lactating Holstein-Friesian cows, selected for either high (H) or low (L) breeding values for live weight (LW), was measured when fed to appetite on hay (7.5 MJ ME/kg DM in 1998) and on pasture (11.1 MJ ME/kg DM in 1999). The H cows were heavier than the L cows in both years (546 v 482 kg; 540 v 464 kg in years 1 and 2 respectively), and the H cows ate significantly (P<0.01) more feed than the L cows in both years (12.5 v 11.1 kg hay DM, and 13.1 v 11.6 kg pasture DM per day in years 1 and 2 respectively. Regression analysis showed that for each 100-kg increase in LW, daily DMI per cow increased by 1.43 and 1.81 kg respectively in 1998, and 1999. Regression analysis of the data after conversion into log10 , showed that DMI was proportional to LW0.66 and LW0.65 in 1998 and 1999 respectively. These results indicate that the genetically heavier cows ate more DM than the genetically lighter cows. Nevertheless, the difference between maintenance costs and FIC (or "net" FIC) may be similar for both strains, so that the smaller intake of the lighter cows does not disadvantage their productive capacity. },
	issn = {1176-5283},
	author = {Caicedo-Caldas A and Lemus-Ramirez V and Holmes CW and Lopez-Villalobos N}
}
@conference {41290,
	title = {Lactation curves for milk traits, live weight and body condition score for heavy and light Holstein-Friesian cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {217-220},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Two genetic lines of Holstein-Friesian cows divergently selected for heavy and light live weight but with similar genetic merit for farm profitability have been developed at Massey University since 1989. The objective of this experimental project was to evaluate differences in production, fertility and feed efficiency between the two lines when they are managed on grazed pasture and submitted to a seasonal system of reproduction. This paper describe the shapes of the lactation curves for yields of milk, fat and protein, live weigh and body condition score of the two lines using the gamma function. Parameters of the gamma function for each of the traits were estimated for each of 84 cows using daily yields of milk, fat and protein and weekly measurements of live weight and body condition scores recorded during the production season 1998-99. Live weights and body condition scores of mature heavy and light cows at calving were 495 and 436 kg and 4.7 and 4.8 units, respectively. Respective values for first-calving cows were 397 and 352 kg live weight and 4.9 and 4.9 units of body condition score. Peak yields of milk, fat and protein for mature heavy (27.6 litres, 1.30 kg and 0.90 kg) were higher than for mature light (25.6 litres, 1.21 kg and 0.86 kg) cows but differences were not significant. Peaks of yield occurred between 27 and 31 days after calving with no significant differences between lines of cows. There were no significant differences between lines for changes in body condition score and persistency of milk, fat and protein production during lactation of mature cows. Compared to mature cows, first-calving cows had lower peak yields of milk, fat and protein. First-calving light cows were the most persistent and maintained the highest body condition score during lactation. Total predicted yields of milk, fat and protein for mature heavy (4,048 litres, 194 kg and 133 kg) were not significantly different from those for mature light (3,774 litres, 182 kg and 127 kg) cows. These results show that there are no significant differences in the shape of the lactation curve for heavy or light mature cows, but first-calving light cows maintained higher body condition score in late lactation. },
	issn = {1176-5283},
	author = {Lopez-Villalobos N and Lemus-Ramirez V and Holmes CW and Garrick DJ}
}
