Design and development of a pig milking device that will cut piglet mortality
11 August 2015
Authors: Emma O’Leary, Kelly Lane and Nicolle Dunphy, Bachelor of Engineering in Biomedical Engineering – Level 7
Piglet mortality in Ireland is significant – thereby driving the need to find a viable alternative to reduce death rates. The aim of our project is to reduce piglet mortality by a significant amount. We wish to make the living environment of both sow and piglet a safer and more desirable place.
The main causes of piglet deaths are starvation, crushing, contamination and diarrhoea. The current solutions to these problems include farrowing crates, milk supplements and piglet teeth clipping – all of which have serious ethical liabilities.
Our approach to this problem is to develop a device that will milk the lactating sow and feed the piglets separately and safely away from the sow, providing an ethically safe, secure environment.
This project was inspired by a close friend of ours – an agricultural science student who, as part of her placement, spent time on a piggery. She was distressed by how many piglets are lost to each litter and approached us as to the need for a humane and ethical engineering solution to this problem. On investigation, we found these concerns to be well founded.
There are major ethical and commercial issues associated with current solutions to the problem of increasing piglet mortality as illustrated hereafter – giving rise to the overarching need for the development of an alternative humane, ethical and commercially viable solution.
Through our project we wanted to design a feeding device that allows piglets to feed safely and separately away from the sow. We aimed to manufacture an ethically safe device to be used in piggeries and organic pig farms.
The development of an automatic milking device was devised as the optimal solution for increasing pig mortality – addressing significantly all four major piglet morality contributing factors and giving a brighter prospect for piglets.
The first major and fundamental decision for our team was to decide between a pneumatically or electrically based system – our main focus being the best, safest operation for both farmer and animal. Comparison of these systems was undertaken:
|Pneumatic System||Unlimited availability of source||Potential Noise|
|Temperature Range||Easy Condenses|
|Electrical System||Response rate||Complexity|
After much research and discussion of the various system merits, we decided that an electrical based system would be most advantageous as we could employ an electrically controlled vacuum pump to create suction in order for milk flow enhancement.
During manufacturing we came up with the idea of adding a pneumatic component to act as a pulsator. This was achieved by inserting a three-way valve onto the air supply tubing which was connected to the vacuum pump and programing a time delay of two seconds on and one second off using a Programmable Logic Controller (PLC). This innovation enabled our developed system to capture the major advantages of both electrical and pneumatic systems.
A vacuum pump is used in our device to create the suction needed to retrieve milk from the sow’s teat. This is achieved by converting the input of mechanical energy of a rotating shaft into pneumatic energy by filtering out the air contained in the system, resulting in a decrease in the internal pressure of the system. The differential difference in pressures is vital as it determines the amount of energy that will be produced.
A vacuum gauge is a very important element as it measures the amount of vacuum pressure inside the vacuum pump. The vacuum gauge reads in either millimetres of mercury (mm Hg) or inches of mercury (in Hg).
The vacuum regulator is used to maintain a constant vacuum at the regulator inlet while a higher vacuum is connected to the outlet. During operation, the regulator remains closed until a point where there is a decrease in vacuum. A decrease in vacuum occurs due to the rise in absolute pressure, this rise in pressure causes the spring to exceed its settings thus opening the vale disk.
Material analysis, selection and optimisation
For material analysis, selection and optimisation, the CES Edu pack 2014 was used as it provides the user with a data base of materials and process information. This provided information on each material which aided the correct selection for materials for desired components of the device.
Aluminium was the main material chosen to build the reservoir tank, the cabinet which is used to hold and protect the pulsator for the vacuum pump and the tap which transports milk to the feeding device. Aluminium was chosen as it has the desired properties needed for both components – high corrosion resistance allowing low maintenance.
Aluminium is resistant to heat and fire preventing scaling, while retaining strength at a degree of different temperature – useful during the cleaning process. This metal is hygienic and non-porous which is also a great advantage to the cleanability aspect of the material, frequently used in applications which require strict hygiene control.
Aluminium is therefore the most suitable material choice due to the following properties:
- Chemical, bacteriological and organoleptic neutrality with regard to the food product;
- Ability to be cleaned so the hygiene and appearance of the product is guaranteed;
- Durability – including resistance to corrosion and aging.
Silicon tubing is selected to transport milk from sow to reservoir tank .This tubing is also used to deliver vacuum from vacuum pump to pulsator and from pulsator to reservoir tank to cause a vacuum. Silicon dairy tubing was the most compatible material to fit all requirements.
It was important that the material was air tight and free from leaks – important for the transport of air from vacuum pump and the transport of milk. This air tight environment within the tubing maintains a sanitary environment and prevents contamination to transported milk. Dairy tubing is easily cleaned and temperature resistant – in colder weather they will not become brittle and break and in hot weather material will not leach into the milk.
Silicon was also the material chosen to make the suction cups which attach to the sow’s teat. Silicon is soft and flexible avoiding sow teat irritation when suction is applied. The silicon suction cups act as a cushion on the sow teat while also generating an air vacuum onto the sow teat. The suction cups are connected to the silicon tubing milk lines using washer plastic to secure an air tight fitting to obtain a vacuum.
BPA free plastic
The teat from which the piglets are fed from is manufactured from BPA free plastic. BPA bisphenol A is a carbon-based synthetic compound. BPA is used to make certain plastics and epoxy resins. However, BPA exhibits hormone-like properties that raise concern about suitability for particular products such as bottles.
The US Food and Drug Administration enforces that all food-containing products are BPA free. The teats utilised for the piglet feeding system are of similar size and shape of the sow’s teat. These teats also contain an air release hole which prevents air building up in the bottle causing gas when the piglet drinks the milk.
The cleaning of our milk reservoir is similar to the cleaning process of dairy bulk tanks used in milking parlours.
There are four main steps to cleaning the reservoir:
- Pre-rinsing with water to wet the surface and rinse off any remaining milk residue;
- Wash with hot soapy water;
- Rinse with water to remove the soap;
- Final sterilising rinse with an approved milk tank sanitiser solution.
In our design of the reservoir there is a large hinged door on top – making cleaning easier and permitting easy access to the interior of the reservoir. This manual cleaning method proves more thorough than automatic methods and allows the reservoir to be carefully inspected during the process.