Managing ruminants

Ruminants such as cattle, buffalo, goats and sheep can be added to your enterprise and managed to supply food (e.g. meat and milk), labour in the form of draught, or money from trading or selling products (e.g. wool).

The ruminant component of CLEM is the most detailed model component as the model needs to simulate the individual growth, mortality and herd dynamics.

The herd

A herd defines the ruminant resource available to the farming system. It is comprised of various Ruminant types each representing a single species or breed, or even a group of individuals managed in a particular way (e.g. a breeding herd or a trade herd, but this can also be managed in a single herd). The initial herd is defined by supplying the number of individuals of each ruminant type by age and sex (see Ruminant initial cohorts).

The Ruminant type component contains all the parameters that describe the given ruminant type or breed. You can have as many ruminant types as you want in your simulation. A list of ruminant types already parameterised are available from the developers.

The simplest simulations involving ruminants have one type or breed of ruminant included. In this situation you can assume that all ruminant based activities will be applied to the herd present. There are simulations where you may need to include additional ruminant types or breeds. These are easily added in the Ruminant herd section as a Ruminant type. Some ruminant activities have parameters that relate to a single breed or are not designed to be performed across multiple breeds and so when working with multiple breeds it is the user's responsibility to ensure that activities know which breed to work with. Defining which breed to consider is performed by adding Ruminant activity group to the simulation tree (see Ruminant groups). Like timers (see Using timers), ruminant groups are respected by activities such that any ruminant groups immediately below or up the simulation tree will all be used to filter the herd before performing an activity. One approach to managing breeds is to create a folder (Activity folder) for each breed and provide an ruminant filter group with a filter (Breed, Equals, Breed name) and place all activities for this breed in the folder.

The Grow ruminants activity is one activity that applies to all breeds and types in the herd. Only one instance of this activity should be provided.

A warning or error will be provided when you attempt to apply an activity across multiple herds or breeds that is not permitted.

Initial herd

The number of individuals present at the start of the simulation are defined under the Ruminant type component. This consists of an initial cohorts component and any number of ruminant cohort components beneath it. A ruminant cohort component identifies each cohort, or group of individuals of the same breed, age and sex. You can also identify whether young individuals are weaned or still suckling. The age of suckling individuals will determine breeding cycles and should be provided with sufficient breeding cows.

Pricing

The ruminant type component also contains pricing details. This allows any activity to access the current price of individuals. Pricing can be set in a number of ways such as per kg live weight, or per head across different size classes. Future activities can be developed to utilise recorded pricing (e.g. MLA live cattle export pricing) or alter pricing based on climate such as droughts or demand.

Growth

The ruminant growth activity is responsible for determining potential monthly intake or the amount an individual of a given size can physically consume. It also calculates the protein available in the diet and energy relations to determine if an individual gains or loses weight and accounts for pregnancy and lactation demands. This activity also determines an individual’s mortality and ageing.

Feeding

In order to grow, individuals require feed, which is supplied by a feeding activity. One feeding activity is required for each type of food or supplement fed to the herd. Food resources are stored in the animal food store and have associated values of dry weight, percent nitrogen and dry matter digestibility that determine quality and subsequent animal growth. A Ruminant feed group is used to specify which individuals in the herd are fed each month, and how much.

Grazing

To allow grazing of pasture, your simulation requires a number of activities. First, a pasture must be managed to represent a paddock or field in which grazing occurs. This requires a pasture resource in the graze food store and an activity to manage this pasture. This activity determines on which land type, with associated soil type, the pasture is located, the size of the paddock, and links to external pasture growth data. Next, the herd must be moved to the paddock with a move activity, which can be used to set the initial location at the start of a simulation. Finally, a graze activity will determine the amount of pasture consumed based on the number of hours grazed and pasture quality.

Distributing food and pasture

A number of management decisions are associated with providing food to a herd and these are simulated in the order your activities are provided. For example, providing an activity to feed hay after a graze activity can be used to supplement the remaining food required, while a feed supplements or quality feed before grazing will ensure the animals eat these resources before grazing pasture. This is an example of how the ordering of activities in the simulation tree will influence model outcomes.

Breeding

The Breed ruminants activity is required if you want to allow breeding to occur in your herd. This activity handles the calculation of conception rates, and manages pregnancy, and lactation through to weaning of offspring. Controlled mating (e.g. with artificial insemination) can be included with associated labour and financial resources required (see Controlled mating), otherwise natural mating will occur whenever males and females of breeding age and condition are located together (see Graze ruminants and Move ruminants).

This activity is required for all breeding and calf growth dynamics through suckling and is needed for Ruminant milking.

Herd management

Herd management and trading activities are required to maintain your herd at a specific size or composition. Such trading can be used to ensure the herd is not too large (see Manage ruminants) and doesn't overgraze the dry season fodder availability. This trading is also used to sell unneeded individuals and maintain breeder bulls and even sell specified individuals at a given time (see Mark ruminants for sale).

Buying and selling

The purchase and sale of individuals is performed in two steps.

1. Mark individuals for sale and create a list of individuals to purchase

It is the role of activities to determine the animals to be purchased or sold. As activities are performed during the time step, any activity can mark individuals for sale (with reason for sale in reporting), or add individuals to the list of required purchases. Additional activities can then remove the for sale mark or clear the purchase list if needed, resulting in the order of activities influencing how animals are defined for sale (note, seasonal drought destocking is undertaken in a later event so can override all previous decisions). Therefore, after all activities have been performed the final state of individuals marked to be sold and the list of individuals to purchase for the time step is known.

These activities can also have associated timers determining the month in which sales are provided. All marks for sale and the purchase list are cleared at the start of the month.

2. Buy and sell individuals

After all activities have determined individuals to be bought or sold in the time-step the Buy and sell ruminants activity is used to arrange the sales or purchases while also including any financial and labour constraints and any associated trucking rules and emissions. This process happens later in the monthly event cycle. A single Buy and sell ruminants activity is required for each of the sales and purchases tasks needed. You can also provide multiple buy and sell activities with different trucking rules and timers to catch particular sales and purchases. Sales and purchases will not happen if there is no buy and sell activity or in months where no buy and sell activity is enabled. As the individuals marked for sale and the purchase list are cleared each month the individuals from previous month's activities cannot be sold if no buy and sell activity is available or the trucking rules restrict the number of individuals (see What to do when resources are limiting).

Herd trading

The Arrange ruminant purchase and Mark ruminants for sale activities are used to manage a trade herd where individuals are bought, fattened and sold to make money. You are able to specify the gender, age and weight of the individuals to be added and the age and weight after which to sell these individuals. The individuals are tagged separate to the general herd and can also be placed in a separate paddock or identified for specific feeding or supplementation.

Location of individuals

A number of management decisions in farming systems relate to the movement of animals. This may be to place animals in paddocks for grazing, or move them through yards for weaning and breeding. The location of every individual in the model is tracked and a number of activities will need to know where to place animals (Manage ruminants, Move ruminants and Wean ruminants). If no location is provided, the default is assumed to be the general yards (value "Not specified") that represents lot feeding. In this situation the animals do not have access to pasture and will need to be fed. It is important to ensure animals are placed in the appropriate location and it can be easy to lose track of individuals which may result in lack of feeding and death, or a bull being moved to a cow paddock and uncontrolled mating commencing.

At present animals can only be moved to pasture paddocks (Graze food store type) or to the general yards (see Move ruminants).

Future activities could allow for much more detailed management decisions behind the movement of animals and implement rotational grazing, mustering or agistment.

Other resources needed

Managing a herd will require additional resources such as labour, finances and water. If included with the herd activities in your simulation these resources can limit the outcome of herd management.

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