Groen Goud Landgoed (Pty) Ltd was established in 1972 and currently consists of twenty farms. These twenty farms accounts for 144 fields, 29 pastures and 12 planted pastures, on which the commercial herd graze. Groen Goud Landgoed (Pty) Ltd has three main ramifications, namely crop enterprises, cattle farming and broiler farming.
Groen Goud Landgoed (Pty) Ltd’s crop enterprises ramification consists of sunflower, maize and wheat. These crops account for more than half of the company’s gross margin income. To maximise the profit, it is necessary to determine on which fields each of the crops should be planted.
The cattle on Groen Goud Landgoed (Pty) Ltd are a commercial Angus herd. The herd currently consist of 723 cows and 27 registered bulls. Young bulls and the heifers that are not withheld for Mr Van Tonder’s own breeding purposes are either sold as weaners, or slaughtered for their meat when they reached the desired weight. Otherwise the heifers are grown until they are ready for the bulls. It is necessary to be able to easily manage the cattle since there are so many. For this reason the cattle should be divided into smaller groups. The smaller groups will be allocated to specific grazing pastures.
Groen Goud Landgoed (Pty) Ltd receives 284 000 day-old broiler chicks at the beginning of each 52-day cycle. The broiler flocks are divided among the eight broiler houses. Each broiler is fed five different rations over a 35-day period to reach the desired weight of 1.8 kg before it is supplied to a processing plant. Hence it is necessary of find the optimal order quantity of each ration to minimise the feeding expenses.
The main objective of the developed Operations Research model was to increase the profitability of Groen Goud Landgoed (Pty) Ltd with regards to the crop enterprise and cattle farming. The model resulted in 18 fields being planted with sunflower, 36 fields being planted with maize, and 50 fields being planted with wheat. The model’s output also resulted in 40 fields left uncultivated.
The cattle allocated to pastures, planted pastures and uncultivated fields accounted for 82.27% of the current Angus herd. The Operations Research model’s results told one that the remaining 133 cattle should be slaughtered for their meat. It was assumed that all of the cattle to be slaughtered were cows.
The validation of the Operations Research model showed what effect different yields would have on the profit. It was found that one has a 48% chance to realise a profit between 8.5 million and 11.5 million rand.
The assumptions were made that the input costs, yields and selling prices of the crops were fixed. It was also assumed that the income generated from slaughtering a cow was fixed. The profit obtained from the Operations Research model was R8 749 197.00, which is an increase of approximately 14.90% compared to 2011’s crop enterprise and cattle farming profit.
To determine the optimal order quantity of each broiler ration required during the five different feed phases of a cycle, an economic order quantity (EOQ) model has been used. The main objective of the EOQ model was to minimise the broiler feed expenses. The results obtained from this model showed that the optimal order quantities were non-integer values.
During the validation of the EOQ model the results obtained were rounded to the nearest ton. This change resulted in fairly small changes in the total cost associated with each order quantity. This model also generated an ordering schedule for each of the five feed phase.
The feasibility of the order quantities were tested against constraints like available storage capacity and whether or not the order quantities could be received at any given time. The conclusion drawn was that it has been found feasible to order 42 tons of pre-starter, 60 tons of starter, 187 tons of grower, 205 tons of finisher and 169 tons of post-finisher on the calculated days as it is stated in the ordering schedule. If these quantities are ordered the annual broiler feed expenses decreased by R1 746 870.49 (or 11.36%) when compared to 2011’s broiler feed expenses.
Thesis (B Eng. (Industrial and Systems Engineering))--University of Pretoria, 2012.