@conference {41621,
	title = {Predicting cow production based on an estimate of animal genotype within a whole farm model},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {93-97},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Body condition score (BCS) has been proposed for inclusion in the New Zealand national dairy index, Breeding Worth (BW), to account for replenishment of body tissue. Currently, the breeding objectives model positively accounts for body tissue mobilisation (through extra yield), but not the negative cost of replenishing body tissue. Two methods have been proposed: 1) Including BCS directly into BW by calculating and assigning an economic value to BCS and 2) Adjusting liveweight Breeding Values (BVs) for BCS, which would mean that liveweight BVs would beexpressed at a constant BCS (indirect method). Energy equations were used to calculate the direct economic value for BCS and included a sensitivity analysis. With an economic weight of $25, the percentage emphasis of BCS in BW would be 3.4\%. Including BCS in BW, either directly or indirectly, had little impact on sire rankings (rank correlations with and without BCS within breed were >0.99) and would only have a small impact on the economic response of BW ($0.02 net /cow/annum) and the improvement in BCS(0.006 BCS units/cow/annum). It is concluded that there would be little benefit to including BCS as an independent trait in BW. Body condition score is already included as a predictor in the genetic evaluation of fertility and breeding values for BCS will be estimated routinely from the fertility model.},
	issn = {1176-5283},
	author = {Beukes PC and Palliser CC and Lancaster J and Leydon-Davis C and Levy G and Folkers C and Macdonald K and Thorrold BS and Montgomerie B and Wastney M}
}
@conference {41610,
	title = {Using a whole farm model to explore options for feed grown on-farm to achieve 1750 kg milksolids per hectare in the Waikato},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {29-34},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Dexcel{\textquoteleft}s Whole Farm Model (WFM) is a computer model of a dairy farm that simulates individual cows and paddocks, with pasture growth driven by observed climate data and with management policies guiding decisions on a daily basis. The aim of the study was to design a farm system to produce 1750 kg milksolids (MS)/ha/yr from feed grown on-farm. An average predicted pasture growth curve was derived by initialising the WFM for a typical all-pasture Waikato farm (3 cows/ha) with "best practice" management policies and running the simulation for 29 years of Ruakura climate data. The model was then used with this average growth curve to design the high producing system. Pasture growth alone (17.3 t DM/ha) did not fulfil the feed requirement for the 1750 kg MS/ha scenario, with an overall feed deficit of 3.1 t DM pasture/ha. Improvements in ryegrass cultivars and N-fertilisers could be expected to increase pasture production by around 10\%, reducing the overall feed deficit to 1.6 t DM pasture/ha. These improvements together with irrigation at 2 mm/day over the three summer months (Dec - Feb) reduced the feed deficit to zero. Irrigation could be replaced by cropping between 11\% and 20\% of the farm in a rotation of annual ryegrass yielding 7 t DM/ha and maize yielding 22 to 28 t DM/ha respectively. },
	issn = {1176-5283},
	author = {Beukes PC and Clark CEF and Wastney ME and Palliser CC and Levy G and Folkers C and Lancaster JAS and Leydon-Davis C and Thorrold BS}
}
@conference {41572,
	title = {Comparing feed allowances to inferred energy intake using data from a dairy grazing farm trial},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {225-230},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The main objective of this research was to investigate whether calculating intake of dairy cows using equations to predict energy requirements provides a good alternative to conventional ways of estimating intake. The method was applied to data from the Dexcel Holstein-Friesian strain trial over three seasons. Feed intake per cow was calculated as the sum of the energy requirements for maintenance, milk production, pregnancy, growth and body tissue mobilisation using measured yields of milk, fat, protein and lactose, live weight and body condition score of cows and calf live weights. In order to compare the estimates of feed intake to the amount of feed offered, linear regressions of calculated (ME) intake (grouped by farmlet) on the amount ME offered per farmlet were performed by season. The relationship between ME intake and ME offered was weak in the first year, with a limited response to increasing the amount of feed offered. This was because all the cows were two-year-olds with lower live weights and milk yields and consequently lower feed intakes. In the subsequent two years of the trial, the relationship between ME intake calculated using the energy equations were 67\% and 72\%. The modern strains of dairy cows responded well to higher levels of feed offered, while the 1970s strain of New Zealand dairy cows failed to increase intake when offered diets of higher total ME. Our results show that energy prediction equations offer a viable and cheap alternative of estimating ME intake of lactating dairy cows.
KEYWORDS: dairy cows; energy intake; strain comparison; efficiency. },
	issn = {1176-5283},
	author = {Pryce JE and Harris BL and Montgomerie WA and Jackson R and MacDonald KA and Glassey CB and Thorrold BS and Holmes CW}
}
@conference {41826,
	title = {Differences in grazing behaviour and herbage intake between genotypes of Holstein-Friesian dairy cows grazing short or long swards},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {236-240},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The objective of this work was to compare dry matter intake and grazing behaviour of different strains (S) of Holstein-Friesian dairy cows during early lactation. Three strains of different origin [two 1990{\textquoteright}s genotypes of Holstein- Friesian from Overseas (OS90) or New Zealand (NZ90) origin and a 1970{\textquoteright}s NZ Friesian (NZ70)] were offered low or high pre-grazing herbage mass (HM) (2100 vs 2800 kg DM/ha) at a common daily allowance (35 kg DM/cow) between September and November 2004. Pasture dry matter intake (IT) and digestibility (D) were determined using the n-alkanes methodology. Time spent grazing (GT) and ruminating (RT) were observed for 24 hours. Intake per empty body live weight unit (ILW) and rate of intake (IRATE) were calculated. There was a significant SxHM interaction (P < 0.001) for IT and ILW. IT was similar at low HM across strains, whereas at high HM, a lower IT was recorded for the NZ70 while it was higher for the OS90. At low HM, ILW was slighter lower in the OS90 than in the NZ90 (P = 0.06) while at high HM both NZ90 and OS90 showed a higher ILW. In vivo digestibility was similar across strains but was higher at high HM (P < 0.001). There was a significant SxHM interaction for GT (P < 0.01) with both NZ strains spending more time grazing at low HM, in contrast, GT was similar across strains at high HM. RT was higher for the OS90 strain than for both NZ strains (P < 0.05) and greater at high HM (P < 0.001). There was a significant SxHM interaction for IRATE (P < 0.05) with the NZ90 and OS90 strains showing similar IRATE at low HM but different at high HM. Results indicate a difference in the ability of the strains to adjust their grazing behaviour to different pre-grazing herbage mass.
KEYWORDS: Holstein-Friesian; high-merit dairy cow; intake; grazing behaviour, herbage mass. },
	issn = {1176-5283},
	author = {Rossi JL and MacDonald KA and Thorrold BS and Hodgson J and Holmes CW}
}
@conference {41539,
	title = {Economic comparison of Holstein-Friesian strains},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {68-73},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The objective of this research was to identify major determinants of net profit per cow. Data were from the Dexcel strain trial over three seasons, in which Holstein-Friesian cows were managed in groups of 12 to 20 cows in eleven farmlets. Milk returns were calculated from lactation yields of milk, fat and protein. Net profit per cow was calculated as the net return from milk sales plus sales of calves minus feed, fertility, health, shed and working expense costs. Annualised present values were derived using asset replacement theory and discounting to account for different numbers of years of data according to the year in which an animal entered the herd. Net replacement costs and average replacement returns were included where animals were replaced before the end of the trial. Partition analysis was used to identify indicators of cow profitability. Partition analysis recursively sub-divides data creating a tree of partitions. Each split is chosen to maximise the difference in profitability between branches of the split. Variables on which data could be partitioned included breeding values, Breeding Worth and traits measured in first parity. The key determinants of profitability were lactation yield of protein and fat, percentage of fat and Breeding Worth. When these variables were fitted to a multiple regression model where the response was annualised present value, the adjusted R2 was 52\%.
KEYWORDS: asset replacement model; economics; dairy cattle. },
	issn = {1176-5283},
	author = {Pryce JE and Harris BL and Glassey CB and Montgomerie WA and Jackson R and MacDonald KA and Thorrold BS and Holmes CW}
}
@conference {41534,
	title = {Impact of farm management decision rules on the production and profit of different strains of Holstein-Friesian dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {40-45},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Management decision rules ({\textquoteleft}old{\textquoteright} rules) have been used at the Dexcel No. 2 Dairy Farm to remove subjectivity from the management of farm systems research and have also been promoted to the dairy industry. A trial involving these rules where three strains of Holstein-Friesian (HF) cows were compared has completed its third season. The trial included two high breeding worth (BW) strains of either North American (OS90) or New Zealand (NZ90) genetics, and one low BW strain of NZ genetics (NZ70). Under the {\textquoteleft}old{\textquoteright} rules the OS90 cows had fewer days in milk than the other two strains, mainly because they were dried off earlier due to their lower body condition score (BCS). In the third lactation {\textquoteleft}new{\textquoteright} rules were applied that allowed cows at the higher feed allowances to be dried off later (but at the same BCS) than would have been allowed under the {\textquoteleft}old{\textquoteright} rules. For the herds receiving the higher feed allowances, this change resulted in increased days in milk (NZ90 + 2 days; OS90 + 17 days) more milksolids (MS) per cow (NZ90 +2 kg; OS90 +21 kg), and more feed required (NZ90 + 10 kg; OS90 + 157 kg DM/cow) with all herds reaching target BCS by their next calving. It is calculated that this reduced the difference in economic farm surplus (EFS) per ha between the NZ90 and OS90 from $488 to $219. These results indicate the need to alter management rules to get the best performance from North American HF genetics.
KEYWORDS: Holstein-Friesian; body condition score; drying-off decision rules. },
	issn = {1176-5283},
	author = {MacDonald KA and Thorrold BS and Glassey CB and Holmes CW and Pryce JE}
}
@conference {41554,
	title = {Modelling the effects of zero-inductions on profitability in dairy systems},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {132-136},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Inductions are an animal welfare issue and regulations aim to achieve < 2\% inductions on a national basis by 2010. There is a need to assess the longer-term impacts of alternative reproduction management strategies on farm economics and their success in solving the problem of poor reproductive performance. Dexcel{\textquoteright}s Whole Farm Model was calibrated against observed data from Lincoln University Dairy Farm where 11\% of the herd was subjected to inductions in the 2002/03 season, but a zero-induction policy has since been adopted. Results from one-year simulations over five different climate years showed a significant decrease in farm profit ($105/ha, P < 0.05) from the benchmark farm with 11\% inductions (following {\textquoteleft}best practice{\textquoteright} guidelines) to a farm where the late-calvers were culled and replaced by bought-in early-calving heifers and where stocking rate was raised moderately (< 10\%) to compensate for the higher proportion of heifers in the herd. Multiple-year simulations reflecting carry-over effects showed that a strategy with a 10-week mating period, annual culling of 25\% of the herd including all empties and replacement with synchronized heifers mated to start calving one week before planned start of calving can match the farm profitability of the {\textquoteleft}Induction{\textquoteright} strategy if implemented consistently for 5-8 years.
Key words: calving spread; modelling; synchrony; mating; replacement. },
	issn = {1176-5283},
	author = {Beukes PC and Thorrold BS and Wastney ME and Glassey CB and Burke CR and Van Bysterveldt AM}
}
@conference {41512,
	title = {Modelling farm systems with once-a-day milking},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {237-240},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Our objectives were to investigate how a cow model, "Molly", deals with once-a-day milking and to use "Molly" in a Whole Farm Model to explore farm systems where once-a-day milking might produce results on a per hectare basis comparable to twice-a-day milking. We compared our model outputs to observed data from a Milking Frequency trial run by Dexcel at a research farm in Taranaki. Changing the rate constants for milk removal and degradation of the lactation hormone complex in "Molly" resulted in the model expressing the acute and chronic effects of once-a-day milking. The once-a-day cow model fed ad lib seasonal grass pasture showed a decrease in milksolids yield (kg/cow) of 31\% in Friesians compared to the observed 28\%. When we used .Molly. in the Whole Farm Model it showed that farm performance with once-a-day milking was 1135 kg milksolids/ha when a Friesian herd was stocked at 7\% higher and their lactation was extended by 14 days compared to a twice-a-day herd (1132 kg milksolids/ha). We conclude that farm performance with once-a-day milking is strongly dependent on selecting cows with higher lactational persistence under once-a-day milking and managing for extended lactations. },
	issn = {1176-5283},
	author = {Beukes PC and Thorrold BS and Wastney ME and Palliser CC and Clark DA}
}
@conference {41392,
	title = {LIC Lecture - The development of environmental best practices for intensive dairying},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {3-6},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {Research since 1995 has focused on soil, fertiliser and animal management factors affecting soil and water quality in intensive dairy systems on imperfectly to poorly drained soils in Southland and Otago. Derived from this on-farm research, best practice for effluent, fertiliser and soil management to ensure that required environmental standards are attained, is outlined. },
	issn = {1176-5283},
	author = {Monaghan RM and Morton JD and McDowell RJ and Drewry JJ and Thorrold BS}
}
@conference {41210,
	title = {Dairy farming, nitrogen losses and nitrate-sensitive areas},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {60},
	year = {2000},
	month = {Jan},
	pages = {256-260},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Dairy farms exhibit large nitrogen (N) fluxes throughout the soil/plant/animal system. These fluxes increase with increasing N inputs and farming intensity, and can lead to significant N losses into the environment. Under New Zealand grazed pastoral systems, the N losses occur predominantly from animal urine. Nitrogen can impact on water quality for human consumption or for aesthetics, recreational use and fisheries via enhanced aquatic plant or algae growth. In this paper, N flows in dairy farms in New Zealand are compared with those in the European Union (EU), where dairy farming is generally more intensive. In the EU, legislation is being used to reduce N losses from intensive dairy farming in nitrate sensitive areas through defined maximum rates of manure application. Progressive reduction in these rates will potentially reduce stocking rates on intensive EU farms such as in the Netherlands, where taxation of farm N surpluses is also used as a deterrent. New Zealand has a lower average farming intensity and lower N losses to the environment than in intensive EU farms. However, farmlet systems research has shown that high N inputs of c. 400 kg N/ha/yr can increase nitrate-N concentration in groundwater by up to twice the recommended maximum for drinking water. In nitrate sensitive areas, such as around Lake Taupo, it is desirable to minimise nitrate leaching and the associated lateral movement to surface water bodies. A range of on-farm options are discussed including limiting external N inputs, increasing N use efficiency via lower protein feed sources, reducing farm dairy effluent N losses, and avoiding direct deposition of excreta to land in autumn/winter using grazing-off or feed-pad systems. Off-farm, there is potential to intercept leached nitrate before it enters surface waters via riparian strips or trenches, or in-stream removal by aquatic plants. In nitrate sensitive areas, there is a need to use a whole catchment approach by examining all contributions to nitrate leaching and not simply targeting one agricultural practice such as dairy farming. },
	issn = {1176-5283},
	author = {Ledgard SF and de Klein CAM and Crush JR and Thorrold BS}
}
@conference {40153,
	title = {Effect of liveweight gain or loss on lamb meat quality},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {127-132},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {No abstract supplied},
	issn = {1176-5283},
	author = {Kirton AH and Thorrold BS and Mercer GJK}
}
@conference {40081,
	title = {Effects of rate of weight gain and weight loss on the relationship between carcass weight and GR measurements in cryptorchid lambs},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {48},
	year = {1988},
	month = {Jan},
	pages = {19-24},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Purebred Texel and Suffolk sheep have been grazed together at Belclare in Ireland since 1977. The Texel sheep originated from the Netherlands and are of similar origin to those imported into New Zealand. A series of studies have been undertaken to examine the growth and carcass composition of the 2 breeds. Relative to the Suffolk the Texel has an altered growth patter; Texel lambs were 19\% heavier at birth than Suffolk lambs after adjustment for non-genetic effects, but by weaning were 8\% lighter (29.08 v 31.76 kg) and the difference increased to 11\% at 2.4 years of age. The difference between the Purebred Texel and Suffolk weaning weights is approximately double the value that has been reported in large scale crossbreeding trials.  Wool production in the Texel was 12 to 22\% higher than the Suffolk breed depending on age. Carcass composition data from 2 separate slaughter trials, using ram lambs, show that the purebred Texel has less subcutaneous fat as a proportion of the carcass than the Suffolk with 75 v 112 g/kg for 18.6 kg carcasses in the first trial and 34 v 80 g/kg and 83 v 125 g/kg when killed at 17.3 and 26.1 kg carcass weight in the second trial. When expressed as a percentage these breed differences are approximately double the values observed in crossbreeding trials. The Texel carcasses also had larger L. dorsi areas and less fat in the internal depots. The food efficiency in the Texel breed was better in the 2 experiments where it was measured, with the differences being significant in 1 trial. Breed differences in composition persisted to maturity with adult Texels having only 78, 81 and 90\% of the weight of subcutaneous, kidney knob, and channel and omental fat deposits relative to the Suffolk. In vivo ultrasonic measurements distinguished similar changes in carcass composition between the breeds with C, Gr and estimated L. dorsi in purebred Texels being 85, 78 and 111\% of Suffolk ewe and ram lambs. The corresponding figures for adult ewes were 79, 83 and 107\%. The carcass composition of most sheep breeds are very similar when expressed as a proportion of mature live weight. The data presented suggests that the Texel is atypical having a modified growth curve and retaining its extreme carcass composition even at maturity.},
	issn = {1176-5283},
	author = {Thorrold BS and Kirton AH and Cranshaw LJ and Mercer GJK}
}
