Phase feeding is feeding a number of successive diets, each differing in protein, energy or amino acid balance to match the nutritional requirements of different age/weight groups of pigs. The benefits include a progressive reduction in diet costs, less nutrients excreted and a potential improvement in feed efficiency. The main disadvantage is the increase in feed storage bins and/or management required.
Benefits of phase feeding.
Previous AUSPIG modelling shows the economic benefits of phase feeding. Chris Brewster in 1995 reported a reduction of up to $3 per tonne for a feeding program for pigs between 12 and 16 weeks of age. In 1997, Bruce Mullan showed that feed costs could be reduced by approximately $3 per pig between 20 and 100 kg liveweight when the diet was changed weekly.
The level of phase-feeding use has increased with the increase in batch farrowing and with larger herd sizes, both producing large numbers of similar age growers at a time, thus allowing diets to be changed frequently (weekly if desired) and the pigs fed from one feed system.
Case study.
This case study shows the benefits of using AUSPIG to develop a phase feeding program. Prior to the AUSPIG analysis, this ‘all-in all-out’ unit used two diets - a grower diet from 25-70 kg and a finisher diet from 71-100 kg liveweight - for on-farm practicality and feed manufacturing reasons (Figure 1).
Replacing the original diets with two diets formulated using AUSPIG, as shown by the dotted line in the graph, would have made considerable savings to the cost of feed. There would still have been an oversupply of amino acids (the section between the dotted line and the pigs’ requirements) because both diets were fed for such long periods.
A more efficient system was to use a larger number of diets so that at any one time the oversupply of nutrients was minimised. The AUSPIG model was used to calculate the amino acid requirements for pigs between 25 and 100 kg liveweight at 20-day intervals. Diets were then formulated to supply 20% above the average pig’s requirements for the first-limiting amino acid at the designated weights (Figure 1 and Table 1). A reformulation of the original grower and finisher diets to supply amino acids 20% above the average pig’s requirements for the firstlimiting amino acid was also included for cost comparison (Table 1).
Table 1. Nutrient contents of diets formulated by AUSPIG, all at 20% above pig requirements
Lower feed cost.
A comparison was made of the growth performance and feed costs (using the same ingredient prices) for the 12 months before and after the AUSPIG phase diets were introduced. There was no reduction in pig performance. Average feed cost was reduced by $35/tonne and feed efficiency improved, resulting in an increase in profit of $3.20/pig compared with the original diets (Table 2).
Table 2. Comparison of farm data and production costs, before and after the implementation of AUSPIG recommendations
1 Based on March 1996 feed prices
Reduction in surplus nutrients.
The other potential benefit of phase feeding is a reduction in the surplus nutrients excreted into the environment. Replacing the original grower and finisher diets with the phase diets would have resulted in a 9% reduction in nitrogen intake and a 15% reduction in nitrogen output compared with the original diets (Table 3). All diets contain 20% above the requirements for the first-limiting amino acid, compared with existing diets.
Table 3. AUSPIG simulation results for pigs fed two diets or phase fed from 25 to 100 kg LW
Author:
Sara Willis
