Aggression, body condition scores and reproductive levels were compared when sows were fed twice vs. six times/day.

Kansas State University researchers teamed up with Keesecker Farms, Washington, KS, to set up a comparative field trial, taking a closer look at the effects feeding schedules have on sow body condition, aggressiveness, sow injuries and mobility and reproduction levels in group-housed sows and gilts.

The eight-month study, conducted in the summer-fall of 2005, included 208 sows and 288 gilts fed either twice a day or six times a day.

Shortly after breeding, sows were housed eight/pen and gilts grouped 12/pen. Twice-a-day feedings occurred at 7 a.m. and 3:30 p.m., while the six times-a-day feedings were split - three in the morning (7:30, 8:00, 8:30) and three in the afternoon (3:30, 4:00, 4:30). Their theory was that more frequent feedings might result in dominant (boss) sows eating their allowance early in the day, leaving the more timid sows to eat their allowance in the afternoon.

The goal of this study was to determine whether the more frequent feedings reduced variation in body weight, backfat thickness, aggressiveness and feet and leg problems, compared to sows fed twice a day.

The 208 sows, with an average parity of 3, were weaned into individual gestation stalls, heat checked by a boar and artificially inseminated twice, then randomly allotted, by parity, to a 10 × 16-ft. pen, with eight sows per pen. Thirteen pens were fed twice a day and 13 pens were fed six times a day.

Sows were weighed and measured for backfat at the P2 position (about 2.5 in. off the midline at the 10th rib) when they entered the gestation pen, then again just before being placed in a farrowing crate.

Gilts were selected for breeding and moved to a breeding barn where they were exposed to a boar, checked for heat and bred twice by artificial insemination. Soon after breeding, they were also allotted to treatments — 12 pens allocated to twice-a-day feeding, 12 allocated to be fed six times per day. Twelve gilts were housed in each 10 x 16-ft. pen.

Due to the limitations of the gilt facility, two groups of bred gilts with similar breeding dates and treatments were combined and moved to larger pens in another facility at about 42 days of gestation. Like the sows, gilts were weighed and measured for backfat at the P2 position when placed in the first gestation pen, then again when they moved at 42 days of gestation.

A grain sorghum-soybean meal gestation diet was fed with feed drops delivering 5.5 lb./day for sows, 4.5 lb./day for gilts, split into twice-a-day feeding or six times-a-day feeding. Pens with sows had two feed drops/pen. Those with gilts had three feed drops for the first 42 days, then five drops to the end of their gestation periods.

Aggressiveness was measured by visually scoring lesions on the sows' and gilts' bodies and vulvas.

Total body lesion scoring used this scale:

1 = No blemishes to some reddening or calluses;

2 = Less than 10 scratches or five small cuts;

3 = More than 10 scratches or five small cuts; and

4 = Most or whole area covered with scratches and/or wounds, with little or no untouched skin.

Visual scoring of the vulva used this scale:

1 = No obvious wounds;

2 = Slight lacerations;

3 = Severe lacerations; and

4 = Severe lacerations and portions of the vulva absent.

Visual appraisal of mobility was scored as:

1 = No lameness of front or rear legs;

2 = Animals with slight structural and/or movement problems;

3 = Severe structural problems, unable to get up or walk.

Hoof integrity was scored as follows:

1 = No obvious lesions or cracks;

2 = Slight lesions on the foot pad and/or between toes;

3 = Severe hoof cracking and lesions on the foot pad and/or between toes.

Lesion scores were recorded on Day 1 (before mixing) and every 14 days until farrowing.

Finally, the vocalization (noise level) was recorded using a data-logging sound meter set to a frequency weighted to be similar to the human ear. This mode is typically used for environmental noise measurements, Occupational Safety and Health Administration (OSHA) regulatory testing, law enforcement and workplace design. Sound meters were positioned at about 6 in. from the feed drop and 3.28 ft. above the feeding area in sow pens only.

What the Trials Showed

The adjoining tables and graphs provide data and details of the findings, but the Kansas State researchers offered these thoughts:

  • Feeding frequency did not influence total or proportional sow removal for reproductive failure. Although relatively few sows were removed for structural problems, more sows in the 2x/day feeding were removed compared to the 6x/day feeding. Feeding frequency did not affect the number of gilts removed for either reason.

  • Sow weight and backfat gains were similar in both treatments (Table 2 and Table 3). Feeding frequency did not affect weight gain in gilts either, but gilts fed 6x/day tended to have higher average daily gains. However, gilts fed 6x/day gained P2 backfat, while those fed 2x/day lost backfat, resulting in a 0.04 in. difference on Day 42. After the 42-day grouping, all gilts lost about 0.04 in. of backfat, but the 42-day difference was maintained until the end of the gestation period.

  • Feeding frequency did not affect reproductive performance as measured by number born alive, stillbirths or mummies in sows or gilts (Table 4).

  • Aggressiveness scores were higher in sows fed 2x/day vs. 6x/day (Table 5). Sows fed 6x/day had fewer structural problems, although scores were generally good. The same held true for gilts.

  • Sows fed 6x/day had lower skin and vulva lesion scores and lower feet and leg lesion injury scores compared to those fed 2x/day (Table 5). Scores did not differ in gilts.

  • Vocalization tended to be higher for sows fed 6x/day, and was highest during their afternoon feedings (Figure 1 & Figure 2). It is important to note that vocalization was only measured at feeding times; therefore, it is not surprising that more feeding events led to more vocalization.

Kansas State University researchers involved in this field trial included: J.D. Schneider; Mike Tokach; Steve Dritz, DVM; Robert Goodband; Jim Nelssen; and Joel DeRouchey. Contact Tokach at

See Table 1