title: Rendering koi carp and creating economic value by making pet food

authors: Wei, Jiaoying

subjects: rendering

abstract: Koi carp is an invasive species fish in New Zealand that severely destroys the aquatic environment in the waterways in the Waikato region. The aim of the project was to look for a method that could make use of captured koi carp. Wet rendering and autoclave rendering was examined for producing fish meal and oil under different processing conditions such as time, temperature and water content.
The water content of raw minced fish was around 69-77%, the solids content was between 23%-31%. Ash content was 6.2-7.4% of the dry solids and fat content between 13.7%-30%. Fish with a high fat content were females containing roe. The meal produced from wet rendering contained 22-28% solids, with 5-9% ash and 14-16% fat on a dry basis, while the stickwater contained 3% solids and 12-39% ash on a dry basis. Autoclave rendering produced a meal containing 26-30% solids, 3-5% ash and 30-31% fat on a dry basis and a stickwater containing 3.2% solids and 27-32% ash on a dry basis. Fat reduction in meal increased with rendering time for wet rendering up to 30% at 40 minutes rendering time, while only a 20% reduction in fat was achieved for autoclave rendering. Wet rendering was selected for producing meals.
Dry pet food and wet pet food was made by mixing rendered fish meal with chicken mince. The dry food was produced by baked while the wet food was produced by steaming. Taste testing showed that cats preferred wet pet food over the dry pet food. The dry pet food had a strong odour and poor palatability. Most cats in the taste testing hesitated to try or eat much of the dry food. It was hard for them to chew the nibbles. Less koi carp meal should be used to improve palatability. The majority of the wet pet food was consumed and it had a better odour.
A customer survey showed acceptance of koi carp for pet food was high. 92% of the participants felt they would buy or try later. People who have pets were more open-minded about using pet food made from koi carp.
An economic analysis showed that 165 tonnes of koi carp could be harvested per year from four Waikato lakes by Huntly, maintaining a biomass density of 140 kg/hectare, down from the current average density of around 200 kg/hectare. To reduce the density down to 100 kg/hectare, koi carp would need to be harvested at 205 tonnes per year for the first 12 years, reducing harvesting to 170 tonnes per after this. Wet pet food production is much more profitable than dry pet food production. The price of each 100 g can of wet pet food to break even should be around $1.7 which is comparable to supermarket prices. This is approximately 10 times the price of dry pet food on a per kg basis. The profit made at $2 per can at 165 tonnes of fish per year is $408K while at 205 tonnes of koi carp the profit is $526K. Dry pet food needs to be sold at just under $6 per kg to breakeven at 165 tonnes of koi carp per year. This decreases with increased harvesting to $5 per kg at 205 tonnes of koi carp per year. If the sales price of the dry pet food is $8/kg, the profit obtained processing 165 tonnes of fish per year is $52K, while at 205 tonnes per year, it is $83K. Dry pet food at the supermarket retails for $5 to $15 per kg.

text: Rendering koi carp and creating economic value by making pet food Koi carp is an invasive species fish in New Zealand that severely destroys the aquatic environment in the waterways in the Waikato region. The aim of the project was to look for a method that could make use of captured koi carp. Wet rendering and autoclave rendering was examined for producing fish meal and oil under different processing conditions such as time, temperature and water content.
The water content of raw minced fish was around 69-77%, the solids content was between 23%-31%. Ash content was 6.2-7.4% of the dry solids and fat content between 13.7%-30%. Fish with a high fat content were females containing roe. The meal produced from wet rendering contained 22-28% solids, with 5-9% ash and 14-16% fat on a dry basis, while the stickwater contained 3% solids and 12-39% ash on a dry basis. Autoclave rendering produced a meal containing 26-30% solids, 3-5% ash and 30-31% fat on a dry basis and a stickwater containing 3.2% solids and 27-32% ash on a dry basis. Fat reduction in meal increased with rendering time for wet rendering up to 30% at 40 minutes rendering time, while only a 20% reduction in fat was achieved for autoclave rendering. Wet rendering was selected for producing meals.
Dry pet food and wet pet food was made by mixing rendered fish meal with chicken mince. The dry food was produced by baked while the wet food was produced by steaming. Taste testing showed that cats preferred wet pet food over the dry pet food. The dry pet food had a strong odour and poor palatability. Most cats in the taste testing hesitated to try or eat much of the dry food. It was hard for them to chew the nibbles. Less koi carp meal should be used to improve palatability. The majority of the wet pet food was consumed and it had a better odour.
A customer survey showed acceptance of koi carp for pet food was high. 92% of the participants felt they would buy or try later. People who have pets were more open-minded about using pet food made from koi carp.
An economic analysis showed that 165 tonnes of koi carp could be harvested per year from four Waikato lakes by Huntly, maintaining a biomass density of 140 kg/hectare, down from the current average density of around 200 kg/hectare. To reduce the density down to 100 kg/hectare, koi carp would need to be harvested at 205 tonnes per year for the first 12 years, reducing harvesting to 170 tonnes per after this. Wet pet food production is much more profitable than dry pet food production. The price of each 100 g can of wet pet food to break even should be around $1.7 which is comparable to supermarket prices. This is approximately 10 times the price of dry pet food on a per kg basis. The profit made at $2 per can at 165 tonnes of fish per year is $408K while at 205 tonnes of koi carp the profit is $526K. Dry pet food needs to be sold at just under $6 per kg to breakeven at 165 tonnes of koi carp per year. This decreases with increased harvesting to $5 per kg at 205 tonnes of koi carp per year. If the sales price of the dry pet food is $8/kg, the profit obtained processing 165 tonnes of fish per year is $52K, while at 205 tonnes per year, it is $83K. Dry pet food at the supermarket retails for $5 to $15 per kg.

year: 2020

title: Three dimensional extension of Bresenham’s algorithm with Voronoi diagram

authors: Au, Chi Kit

subjects: voronoi diagram

abstract: Bresenham’s algorithm for plotting a two-dimensional line segment is elegant and efficient in its deployment of mid-point comparison and integer arithmetic. It is natural to investigate its three-dimensional extensions. In so doing, this paper uncovers the reason for little prior work. The concept of the mid-point in a unit interval generalizes to that of nearest neighbours involving a Voronoi diagram. Algorithmically, there are challenges. While a unit interval in two-dimension becomes a unit square in three-dimension, “squaring” the number of choices in Bresenham’s algorithm is shown to have difficulties. In this paper, the three-dimensional extension is based on the main idea of Bresenham’s algorithm of minimum distance between the line and the grid points. The structure of the Voronoi diagram is presented for grid points to which the line may be approximated. The deployment of integer arithmetic and symmetry for the three-dimensional extension of the algorithm to raise the computation efficiency are also investigated.

text: Three dimensional extension of Bresenham’s algorithm with Voronoi diagram Bresenham’s algorithm for plotting a two-dimensional line segment is elegant and efficient in its deployment of mid-point comparison and integer arithmetic. It is natural to investigate its three-dimensional extensions. In so doing, this paper uncovers the reason for little prior work. The concept of the mid-point in a unit interval generalizes to that of nearest neighbours involving a Voronoi diagram. Algorithmically, there are challenges. While a unit interval in two-dimension becomes a unit square in three-dimension, “squaring” the number of choices in Bresenham’s algorithm is shown to have difficulties. In this paper, the three-dimensional extension is based on the main idea of Bresenham’s algorithm of minimum distance between the line and the grid points. The structure of the Voronoi diagram is presented for grid points to which the line may be approximated. The deployment of integer arithmetic and symmetry for the three-dimensional extension of the algorithm to raise the computation efficiency are also investigated.

year: 2010

title: Kotahi anō te tupuna o te tangata Māori, ko Ranginui e tū nei, ko Papatūānuku e takato nei. Colonisation through Christianity

authors: Wallace, Ritane

subjects: Christianity

abstract: This thesis will look at the role that Christianity and the missionaries played in the colonisation of Māori during the 1800s. With discussion about the colonisation of Aotearoa, it is generally felt within the Christian community that the work of the missionaries and the Crown are separate and therefore the universal belief is that the missionaries are pardoned from the critique of their work here in Aotearoa. However, Christianity throughout history has always been a doorway for the British Empire to enter land that was not their own.
  
It is widely accepted from the viewpoint of Christianity that it holds a religious superiority over all Indigenous people and their religions dating back to Pope Alexander VI and the issuing of the Papal Bull “Inter Caetera” in 1493 to justify Christian European explorers’ claims on land and waterways they allegedly discovered. Christian hegemony shaped missionary views of the ‘other’ and justified the assimilation of Indigenous people into European Christianity. The negative effects of Christianity on Māori far outweigh the positives as mission stations up and down Aotearoa contributed heavily to the loss of language, religion, and land, the three foundational pillars of Māori and other Indigenous peoples around the world.
   
The thesis seeks to hold the missionaries and Christianity to account for its contribution to the colonisation and religious assimilation of Māori into a foreign and unrelated belief system.

text: Kotahi anō te tupuna o te tangata Māori, ko Ranginui e tū nei, ko Papatūānuku e takato nei. Colonisation through Christianity This thesis will look at the role that Christianity and the missionaries played in the colonisation of Māori during the 1800s. With discussion about the colonisation of Aotearoa, it is generally felt within the Christian community that the work of the missionaries and the Crown are separate and therefore the universal belief is that the missionaries are pardoned from the critique of their work here in Aotearoa. However, Christianity throughout history has always been a doorway for the British Empire to enter land that was not their own.
  
It is widely accepted from the viewpoint of Christianity that it holds a religious superiority over all Indigenous people and their religions dating back to Pope Alexander VI and the issuing of the Papal Bull “Inter Caetera” in 1493 to justify Christian European explorers’ claims on land and waterways they allegedly discovered. Christian hegemony shaped missionary views of the ‘other’ and justified the assimilation of Indigenous people into European Christianity. The negative effects of Christianity on Māori far outweigh the positives as mission stations up and down Aotearoa contributed heavily to the loss of language, religion, and land, the three foundational pillars of Māori and other Indigenous peoples around the world.
   
The thesis seeks to hold the missionaries and Christianity to account for its contribution to the colonisation and religious assimilation of Māori into a foreign and unrelated belief system.

year: 2021