TECHNICAL ARTICLES Swine

Feeding Dalland 80 Line Finishers

Introduction

Meadow Feeds has been conducting research into developing feeds and feeding strategies, which would allow us to make recommendations and provide nutrition applications that aim to feed local pig herds according to genotype. To understand the potential benefits that can be derived from feeding various genotypes properly, it is necessary to look at the interaction between the animal and what is being fed. Different breeds and crossbreeds have different rates of protein (lean) and fat tissue deposition and will therefore have different energy and amino acid requirements.

The TOPIGS Dalland Finisher

Offspring of the 80 line sires (Tempo boar) have a high feed intake capacity (Personal Communication: TOPIGS International, 2002). The reason for this is that the 80 line has been selected for feed intake capacity since the early 1980’s. This genetically higher feed intake potential of the progeny requires different feeding strategies and feed composition.

It is important to maximise muscle growth at an early age while the young animal is capable of putting down protein without excess fat. For this good starter diets are required. During the grower and finisher period the animals need a certain quantity of energy and protein (amino acids) to reach optimal daily gain (protein and fat deposition). For this reason it is important that the ratio of protein to energy is correct.

To reach maximum protein deposition rates whilst maintaining daily gains and carcass quality requires an “optimisation” of the diet specifications. An excessive intake of protein may be a metabolic burden and excessive intake of energy may just be deposited as fat.

The Experiment

As such an experiment was conducted to study the performance characteristics of Dalland gilts as affected by the ratio of protein to energy as well as to study the feed intake capacity of the animal using a nutrient dilution technique. Biological and economic performances were measured.

The experiment was conducted at the pig production and research facilities of the ARC Animal Nutrition and Animal Products Institute. The institute is located at Irene on the Gauteng Highveld. For the purpose of the study 240 grower Dalland gilts were used. The pigs entered the trial at an average live weight of 30.4 kg. Animals were blocked according to weight and within blocks randomly allocated to the different treatments.

Six treatments were fed in a phase feeding program and are described as:

• Treatment 1 Very High Lysine:Energy (3 feeds from 28 to 95 kg LW)

• Treatment 2 High Lysine:Energy (3 feeds from 28 to 95 kg LW)

• Treatment 3 Medium Lysine:Energy (3 feeds from 28 to 95 kg LW)

• Treatment 4 Low Lysine:Energy (3 feeds from 28 to 95 kg LW)

• Treatment 5 Dilution Effect (3 feeds from 28 to 95 kg LW)

• Treatment 6 Typical Farm Nutrition Program (4 feeds from 28 to 95 kg LW)

The Results

Results are shown in Table 1. Average daily gain (ADG) did not differ significantly (P = 0.598) between dietary treatments. Treatment 1 showed the highest ADG at 850 g/pig/day for the duration of the trial. Days to slaughter did not differ significantly (P = 0.668) between treatments. Treatment 1 reached the average slaughter mass of 95 kg the quickest at 78.8 days on trial.

Live weight feed conversion efficiency (LW FCR) was calculated from the live weight (kg) gained during the trial period and the amount of feed (kg) consumed during the same period. Significance at the 10 % level (P<0.10) was observed for Feeds 1 and 3 with Treatment 6 performing better on feed 1 than Treatments 3, 4 and 5 but the same as Treatment 1 and 2, and Treatment 5 performing worse on Feed 3 than any other Treatment.

Total feed intake showed significant differences (P = 0.029) for Treatment with animals on Treatment 6 eating significantly less than animals on Treatments 3, 4 and 5, and animals on Treatment 5 eating significantly more than animals on Treatments 1, 2 and 6.

Analysis of variance showed no significant differences for slaughter weight (P=0.140) and dressing percentage (P=0.482). Differences at the 10% level of significance (P<0.1) were observed for back fat thickness measured with the intrascope (P=0.067). Back fat thickness was higher for Treatment 3 and 4 than for Treatment 1, 2, 5 and 6 (Table 1). Within the classification groups the distribution of carcasses is shown in Table 2.

2 x TABLES

Discussion

Feed intake effects and carcass quality differences have been clearly demonstrated. Treatments 2 and 6 had significantly lower feed intakes than treatments 3, 4 and 5. The protein (amino acid) levels of Treatments 3 and 4 were lower relative to energy than Treatments 1, 2 and 6. Treatment 5 (the dilution treatment) had similar levels of protein relative to energy as Treatment 1 and 2 but the overall nutrient density in protein (amino acid) and energy had been reduced proportionately by the same dilution factor. Lysine to energy ratios were defined for each feed, in each treatment, and the same ideal protein profile was used to set the amino acid concentrations.

The feed intakes observed on Treatments 3 and 4 indicate that the pigs increased their feed intake in an effort to consume sufficient amounts of the essential amino acid lysine or sufficient amounts of the second or third limiting amino acid (usually threonine). The carcass characteristics of these animals showed much higher back fat levels and lower lean meat percentages. It is a well-known fact that if we underfeed protein (amino acids) that pigs will adjust their feed intakes to consume more of the limiting amino acid. At the same time the animals will increase their energy intakes. In these cases an increase in fat deposition has been recorded as the animal compensates for the “protein deficiency”.

Treatment 5, the dilution treatment, showed significantly higher feed intakes than treatments 1, 2 and 6. These animals were eating to satisfy their requirements for protein and energy and it is highly probable that the feed intake response observed was driven by the energy content of these diets. This response, coupled with the fact that the pigs on Treatment 5 reached slaughter mass at the same time as the other treatments, exhibits an important characteristic of this genotype in feed intake capacity. This could be an important economic trait during periods of high raw material input costs, where lower density rations, balanced to ensure optimal levels of amino acids relative to energy, could be considered to exploit the feed intake capacity of the animal.

The program would need to be carefully balanced and one would need to ensure that the environment would allow the animals to achieve the necessary nutrient intakes. The specification chosen would be one that offers a cost versus benefit trade off where margin over feed cost is optimised relative to that, that may be achieved with a higher nutrient density feed.

Carcass characteristics for the animals on Treatment 5 showed that, when the feeds are balanced for lysine relative to energy at a ratio that is found to optimise biological efficiencies for this genotype, one could expect similar returns in carcass characteristics, as one would achieve on diets higher in amino acids and energy. The feeds in Treatment 5 were cheaper than the feeds in Treatments 1 and 2 by between R 80 and R 100 per ton. The higher feed intake and subsequent feed conversion ratio offset any saving in feed cost. Adopting a nutrient density versus feed intake capacity strategy using this genotype would require rigorous calculations of benefit (income or return) over feed cost to determine the on-farm application exploiting this trait. Obviously this would need to be carefully balanced against management, environment and herd health to ensure that feed nutrient utilisation is optimised with lower density feeding.

Treatment 1 and 6 performed well in both the Hennesy grading probe back fat and percentage meat measurements. These “high lean” diets in the early growth phase for Treatments 1 and 6, and for Treatment 1 in the later stages of growth produced excellent carcass characteristics in the POR grades. They were also highest in grading in the P and O categories, which would have an economic implication for producers.

Although Treatment 6 produced excellent carcass characteristics, these high nutrient density diets (high energy) did not provide an adequate return in feed intake or carcass grading income to warrant the investment in these specifications in this trial. This genotype has shown the ability to perform equally on diets of lower energy density.

At a margin over feed cost level Treatment 1 and 2 performed the best, and on average were about R 10 more profitable per pig than Treatment 6 and R 13 more profitable per pig than Treatment 5.

Conclusion

The research adds to the information available on this genotype. The results will allow us to more accurately predict those lysine:energy ratios in a phase feeding program, as well as that energy density that optimises biological and economic performances of these lean line gilts.

Multi-phase feeding and balanced nutritional inputs offers performance benefits derived from feeding genotypes properly. The economic and biological opportunities that exist need to be exploited in well-defined product offerings and nutritional solutions.

Date published: 2003-10-06

Author:
Gary Arnold

Publication: N/A