@conference {41613,
	title = {In vitro production of volatile fatty acids from forages},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {50-54},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Volatile fatty acid (VFA) production from a range of fresh forages was measured in vitro over 24 hours (h). The forages comprised temperate and tropical grasses, legumes (including some containing condensed tannins; CT), herbs and silages, all of which were minced to resemble chewed forage and incubated in buffered media. Volatile fatty acid concentrations were measured in triplicate for each feed at 0, 6, 12 and 24 h. On average, VFA yields were 131, 226 and 311 mg/g dry matter (DM) between 0 - 6, 0 - 12 and 0 - 24 h, and the highest yields were from legumes (384 mg/g DM) and lowest from plantain (176 mg/g DM) after 24 h. Legumes containing CT produced 28\% less VFA than other legumes. The acetate + butyrate:propionate (A+B:P) ratio showed a substantial difference between forage types, ranging from an average of 2.5 (legumes) to 3.5 (tropical grasses) after 6 h, but differences between forage types diminished after 24 h. Multiple regression analysis showed a weak inverse relationship with NDF (neutral detergent fibre) after 6 h, but there was no clear relationship with particle size, chemical composition or digestion rates at 12 and 24 h. },
	issn = {1176-5283},
	author = {Burke JL and Waghorn GC and Brookes IM and Chaves AV and Attwood GT}
}
@conference {41413,
	title = {Empirical assessment of the CNCPS model to predict performance of dairy cows fed pasture with silage supplements},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {91-95},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {The goal of this work was to determine the accuracy and utility of the Cornell Net Carbohydrate and Protein System (CNCPS) model to predict milk production from diets based on pasture and forage supplements. Data were obtained from studies in which pasture was complemented with contrasting silages including maize, pasture, sulla, lotus and forage mixtures, comprising 30-40\% of dry matter intake (DMI). Twelve diets were used in this evaluation. DMI, live weight (LW), days in milk, and diet composition were determined during the trials and used as inputs in the model. Across all diets, a significant (P<0.01) relationship existed between predicted and actual values for DMI (r2=0.63), milk yield (r2=0.64) and LW change (r2=0.57) but there were still large unexplained sources of variation and the slopes of the regression lines were significantly (P<0.01) different than 1. No significant mean bias was observed for any of the variables, but the slope of residual differences against predicted values was significantly different from zero (P<0.01 for milk yield and LW change; P<0.06 for DMI). The results indicate a satisfactory prediction of milk production when cows are neither gaining nor losing weight, but that a systematic bias exists probably because of the CNCPS model{\textquoteright}s failure to account for nutrient partitioning. },
	issn = {1176-5283},
	author = {Chaves AV and Brookes IM and Burke JL and Waghorn GC and Woodward SL}
}
@conference {41338,
	title = {Digestion kinetics of ryegrass},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {157-162},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {Changes in ryegrass maturation, with accompanying decreases in nutritive value and feed intake, have significant consequences for the dairy industry. Thus digestion kinetics of ryegrass were measured in samples differing in both physiological age (days after cutting) and calendar date to form a database that can be used as a guide to calculate the extent and type of supplement needed to match nutrient supply with requirements of grazing dairy cattle. Ryegrass pasture was mown on 21 August, 11 September, and 21 September and samples of approximately 2 kg were harvested from those dates at 7-14 day intervals for chemical analyses by cutting to 5 cm above soil level. These samples were used for in sacco and in vitro incubations to determine rate of digestion and proteolysis. The principal finding was a rapid decline in crude protein content from about 22.5\% of DM harvested at 21 days to 7.2\% for that harvested after 67 days. These changes were associated with increases in the neutral detergent fibre (NDF) fraction of the DM (42.1\% to 56.3\%) and in lignin concentration (2.49\% to 3.07\%). Changes were more rapid in late-cut than early cut forages. The principal consequences of increased maturity were slower degradation rates of DM (k= 0.067 to 0.038/hour) and CP (k= 0.122 to 0.052/hour) and less degradation of crude protein to ammonia. This data can be used in conjunction with dairy cow models (e.g., CNCPS) to predict animal performance. },
	issn = {1176-5283},
	author = {Chaves AV and Waghorn GC and Brookes IM and Hedderley D}
}
@conference {41365,
	title = {Improving animal performance using forage-based diets},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {267-272},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {<p>New Zealand livestock systems are based on ryegrass dominant pastures, but they are unable to maximise animal production. Limitations of ryegrass-based pastures are reviewed, and opportunities for using alternative forage species to complement pasture and improve animal production are discussed. Ryegrass pastures have low dry matter contents and high fibre concentrations which restrict feed intake so animal energy requirements are often not met. High crude protein (CP) concentrations in spring and rapid proteolysis in the rumen produces excess ammonia which must be excreted, whereas summer pastures contain insufficient CP. Chicory, red clover, lotus species, sulla, lucerne and maize silage are examples of forages that can complement ryegrass to improve animal performance. More information is needed to define digestion and fermentation of fresh forages in the rumen, but in vitro and in sacco techniques have been used to evaluate these parameters for grasses, legumes, herbs and silages. This information with feed composition data will be used in computer simulations to predict forage mixtures able to complement pasture at different times of the year. The challenge will be to complement the changing ryegrass pastures with other forages to improve animal welfare, productivity and profit.</p>},
	issn = {1176-5283},
	author = {Burke JL and Waghorn GC and Chaves AV}
}
@conference {41231,
	title = {Digestion kinetics of mature grasses},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {61},
	year = {2001},
	month = {Jan},
	pages = {8-12},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Digestion kinetics were measured for mature (green and non-senescent) components of five grass species using in sacco and in vitro incubations to define rates of degradation and nutrient release. The data will be incorporated into a dairy nutrition simulation model to identify limitations in nutrient supply to cows grazing mature pasture in late spring. Perennial ryegrass, tall fescue, Yorkshire fog, phalaris and paspalum were hand separated into leaf, stem and inflorescence for incubations. Percentages of fibre (NDF) in DM fractions ranged from 50-69\% (leaf), 63-75\% (stem) and 50-68\% (inflorescence). Crude protein concentrations in the DM of the respective fractions were 7.5-23.7\%, 3.8-8.3\% and 7.9-12.3\%. Soluble DM (\% of the total) determined after mincing accounted for 31-53\% of leaf, 26-55\% of stem and 20-48\% of inflorescence, and fractional (h-1) degradation of the insoluble DM was very slow, ranging from 0.034-0.113 (leaf), 0.025-0.036 (stem) and 0.033-0.072 (inflorescence). After 24 hours of in vitro incubation plant nitrogen content become limiting for fermentation in most instances. },
	issn = {1176-5283},
	author = {Chaves AV and Waghorn GC and Brookes IM and Burke JL}
}
