Feed efficiency in swine.

Abstract: Purebred boars were used to evaluate the effect of breed on feed efficiency. Analysis" of variance indicated that breed had a significant influence on feed efficiency. All possible trait correlation coefficients are reported and the trait least squares means were significantly separated. Feed efficiency was plotted to display that swine breeders improved feed efficiency over the 17 years of swine performance testing.

Key Words: Feed efficiency, swine performance traits

Summary

Purebred boars evaluated at the Southeast Missouri State University Swine Test Station were used to study the breed effect on feed efficiency. Two thousand and forty-one boars of seven different breeds were used in the study. Feed efficiency was measured via the pen method. Each pen contained three boars. Feed efficiency was found to be significantly (P>.05) effected by breed of boar. Data in Table 1 revealed that among the breeds used in the study Chester White displayed the most desirable feed efficiency. This study was conducted over a 19-year period. Analysis of variance revealed that year was a significant source of variation. Figure 1 displays that swine breeders did reduce feed required per unit of gain.

[FIGURE 1 OMITTED]

Introduction

Feed efficiency measures the volume of feed required per unit of gain. This trait is economically important because feed costs account for 60-70% of the total production costs for commercial swine producers, Taylor et al (1998). Obtaining feed efficiency records requires keeping animals in individual or group feed records. This is very expensive for the commercial swine producer. However, feed efficiency can be improved by testing and selecting individual pigs for gain and backfat. The improvement occurs because fast-gaining lean pigs tend to be more efficient in feed utilization Lasley, (1987).

The major objectives of this experiment were to compare the feed efficiency among different breeds of swine, determine if feed efficiency had improved across time, and to study the correlation coefficients between feed efficiency and swine traits of economic importance.

Material And Methods

Data was obtained from 2147 boars of seven different breeds evaluated at the Southeast Missouri State University Swine Test Station of Cape Girardeau, Missouri. This represents the boars evaluated in a 19-year period. Feed efficiency was calculated on each animal in the study. On-test weight was 31.75 Kg. The off-test weight was 104 Kg. Boars were evaluated in a three-boar sire group. The feed efficiency is an average of the sire group of three.

Least squares means, correlations, and analysis of variance were calculated from these data using a Statistical Analysis Systems package designed and implemented by Barr and Goodnight, Department of Statistics, North Carolina State University.

Results And Discussion

The mean squares and standard deviations for feed efficiency are presented in Table 1. Breed differences were important (P<.05) for feed efficiency. The breed means were separated using the least significant difference test (P<.05). The means that display differences were separated by use of superscripts. Chester White displayed the most desirable feed efficiency. Table 2. displays the analysis variance for the two effects used in the study of swine feed efficiency across time. Breed of swine and year was a highly significant source of variation for feed efficiency.

Figure 1. displays feed efficiency plotted across the years of the boar testing. Year was a significant source of variation. Swine breeders did reduce the feed required per unit of gain across the 17 years of boar evaluation.

Table 3. contains correlation coefficients and their level of significance between various traits. Feed efficiency was positively correlated to average daily gain (P<.01) and days of age to 104 kilograms live weight. Feed efficiency was negatively correlated with loin muscle area (P<.01) and backfat thickness (P<.01). These correlations indicate boars in this study with desirable feed efficiency grew faster but displayed higher levels of fat thickness and possessed smaller loin muscle area.

Table 1. Anova Results and Standard Deviations for Feed Efficiency

Breed                    N   Mean * (1)   Standard Deviation

Chester White          247        1.17a                 0.19
Spot                   159        1.23b                 0.28
Yorkshire              447        1.24b                 0.04
Berkshire & Poland's   147        1.25b                 0.08
Duroc                  723        1.30c                 0.49
Landrace               170        1.31c                 0.53
Hampshire              252        1.36c                 0.56

Means in the same column not sharing common superscripts differ
(P<.05)

* Significance level for effect of breed from analysis of variance
where designated

(1) Mean Feed Efficiency = kilograms per kilogram of gain

Table 2. Analysis of Variance for Swine Feed Efficiency

Effects          df   PR > F

Breed of Swine    7   0.0001
Year             16   0.0001

Table 3. CORRELATION COEFFICIENTS AND LEVELS OF SIGNIFICANCE
BETWEEN VARIOUS TRAITS

       DAYS   ADG     LE      BF      F/G

DAYS          -0.67    0.10    0.08     .002
               0.01    0.01    0.01    0.91
ADG                   -0.15   -0.08    0.11
                       0.01    0.01    0.01
LE                             0.29   -0.91
                               0.01    0.01
BF                                    -0.25
                                       0.01
F/G

DAYS = Days of age to reach 104 kg. Weight

ADG = Average Daily Gain

LE = Loin Muscle Area

BF = Back Fat Thickness

F/G = Feed Efficiency

Literature Cited

Lasley, J. F. 1987. Genetics of Livestock Improvement. Englewood Cliffs, N J: Prentice-Hall.

Taylor, Robert E. and Thomas G. Field. 1998. Scientific Farm Animal Production. Upper saddle River, N J: Prentice-Hall.

William W. Ellis

Southeast Missouri State University

Department of Agriculture

Cape Girardeau, MO. 63701