Introduction

Previous research at this center based on computerized feed intake recording equipment has shown considerable variation in the feeding patterns of growing and finishing pigs (Hyun, 1997). In particular, the variation in feeding behavior among animals of the same genotype, sex and weight fed the same diet and housed in the same pen appears to be huge. For example, Hyun et al. (1997) showed that the average number visits to the feeder for individual pigs ranged from 6 to 26 per day. In addition, the day to day variation in feed intake for individual pigs also appears to be considerable and can be as high as 100% or even greater on consecutive days for some animals Hyun, 1997). However, there has been little research to evaluate the impact of day-to-day variation in feed intake levels on growth performance. This study was carried out to investigate the impact of daily variation in feeding level on growth performance in two weights of pigs.

Experimental Approach

The study was carried out a 3 x 2 factorial design with three feeding regimens and two weights of pig. The feeding regimens were as follows:

1. Ad libitum (AL).
2. Restrict fed to 95% of ad libitum intake, with the feeding level being kept constant from day to day (95AL-FIXED).
3. Restrict fed to 95% of ad libitum intake, with the feeding level being varied from plus 15% to minus 15% of ad libitum intake on consecutive days (95AL-VAR).

The feed intake of the pigs on the AL treatment was measured on a daily basis and this data was used to calculate the feeding level (95% of ad libitum intake) for the other two feeding regimes.

The study was carried out over a 42-day period with the two weight ranges studied being from from 44 to 80 kg and 84 to 123 kg, respectively. A total of 72 barrows that were the progeny of PIC line 326 sires and C15 dams were used in the study, giving 12 pigs per feeding regime x weight subclass. Pigs were housed in individual pens which had fully slatted floors and contained an ad libitum feed hopper and nipple water drinker. The diet used over the lighter weight range contained 18 % crude protein, with that used for the heavier animals having 16% crude protein. Animals were weighed once per week to monitor growth rate and feed intake was recorded on a weekly basis. Pigs were ultrasonically scanned at the start and end of the study. Longitudinal scans were taken immediately anterior to the last rib and average backfat thickness and loin eye depth were automatically measured on the scans.

Results

The results for the impact of feeding regimen on growth performance and ultrasonically measured carcass characteristics for growing and finishing pigs is summarized in Table 1. As anticipated, the performance levels and carcass measurements were substantially different for the lighter and heavier weight ranges studied. However, there were no statistically significant differences between the feeding regimes for growth and carcass traits for either weight range. Pigs fed ad libitum did have higher feed intakes and growth rates than those on the other two regimens. In addition, for growing pigs fed at 95% of the ad libitum treatment, there was a numerical trend for pigs on the variable feeding regimen to grower faster than those on the fixed regimen; however for finishing pigs, the reverse trend was seen.

Conclusions

The results of this study suggests that fluctuating daily feed intakes within the range of 15% either side of the mean do not significantly impact animal performance or carcass leanness. The impact of wider daily fluctuations in feed intake, which are common in group-housed pigs on automated feed intake equipment and also are likely to occur under commercial conditions, is uncertain and needs to be studied.

References

Hyun, Y. 1997. Nutritional and environmental factors affecting feed intake level and pattern in growing and finishing pigs. Ph.D. Thesis, University of Illinois, Urbana, IL 61801.

Hyun, Y., M. Ellis, F. K. McKeith, and E. R. Wilson. 1997. Feed intake pattern of group-housed growing-finishing pigs monitored using a computerized feed intake recording system. Jornal of Animal Sciences. 75:1443-1451.

Tables available in PDF version