Feeding Frequency Has Limited Impact On Group-Housed Sows

Kansas State University (KSU) researchers recently concluded that increasing the number of daily feedings did not dramatically impact the performance or welfare of group-housed sows and gilts in gestation.

The National Pork Board-sponsored research project investigated ways to deal with the “boss sow” syndrome that occurs when gestating sows and gilts are housed in groups. Dominant sows consume more feed than desired, often at the expense of other sows in the group.

The KSU research team increased the feeding frequency from two to six times/day and spaced the feedings in an attempt to satisfy the boss sows. Researchers theorized that a more satisfied boss sow would reduce the variation in sow weight gain and injury among penmates.

The experiment included 496 group-housed gilts and sows on a commercial sow farm in northeastern Kansas.

In the study, 208 sows averaging three parities were randomly allotted to treatments consisting of 13 pens/treatment. After weaning, sows were moved to a breeding facility for boar exposure and were housed in crates until estrus was detected.

Sows were inseminated twice. The day after the second service, 24 to 40 sows were randomly allotted by parity, and assigned in groups of eight to 16 × 10-ft. pens. Sows were weighed and backfat was measured at the last rib, 2.5 in. off the midline (P2 position) when allotted to their group, then again as they entered the farrowing house.

Included in the study, 288 replacement gilts were brought to a breeding facility and housed in groups with boar exposure until estrus detection. Gilts were inseminated twice and moved to 16 × 10-ft. pens, with 12 gilts/pen.

Gilts were housed in this facility until Day 42 of gestation, when gilts of similar breeding dates and treatment were combined and moved to another facility with larger pens until farrowing. The 12 replicates/treatment were combined to give six replicates/treatment after Day 42 of gestation. Gilts were weighed and backfat measured at the P2 position at Day-42 allotment and again before farrowing.

All gilts and sows received a grain sorghum-soybean meal gestation diet. Feed drops were set to provide 5.5 lb. of feed/sow/day and 4.5 lb./gilt/day. All feed was dropped onto solid concrete floors.

Feed drops were scheduled twice daily, at 7:00 a.m. and 3:30 p.m., for specific groups. Other groups received six feed drops/day at 7:00 a.m., 7:30 a.m., 8:00 a.m., 3:30 p.m., 4:00 p.m. and 4:30 p.m. Feed drops were set at the beginning of the trial. Adjustments were made if a sow or gilt was removed from the trial.

To accommodate the amount of daily feed needed, sow pens had two feed drops. Gilt pens had three feed drops from Days 0 to 42 and five feed drops/pen from Day 42 to farrowing. An Accu-Drop Feed Dispenser by Automated Production (AP) Systems was used.

Sow and gilt aggressiveness was determined by visually scoring lesions on the total body and vulva. Total body lesions were scored as follows:

#1 — No blemishes to some reddening or calluses;

#2 — Less than 10 scrapes or five small cuts;

#3 — More than 10 scratches or five small cuts;

#4 — Most or the whole area was covered with scratches/wounds with little or no untouched skin.

Similarly, visual scoring of the vulva included:

#1 — No obvious wounds;

#2 — Slight lacerations;

#3 — Severe lacerations observed; and

#4 — A female with severe lacerations and portions of the vulva absent.

Structural integrity for sows and gilts was performed by visual scoring of feet and legs on a similar scoring system ranging from 1 (no lameness in front or rear legs) to 3 (severe structural problems and inability to get up or walk).

Hoof integrity scores were also observed. Lesion scores were recorded before mixing on Day 1, and every 14 days until farrowing.

Vocalization was recorded using an Extech Model 407764 data logging sound level meter. The sound meters were placed near the feed drop and above the feeding area. A directional cone was attached to the microphone to decrease extraneous noise from adjacent pens. Vocalization was not measured in gilts due to the combining of pens and movement to another facility on Day 42.

Researchers found the vocalization was greater in the two-hour period around the morning and afternoon feeding periods for sows fed six times/day vs. sows fed twice daily. As Figures 1 and 2 on page 30 show, vocalization increased with each feeding and returned to baseline values.

Sows fed six times/day had three distinct vocalization peaks during each feeding period, indicating they were more active over the feeding period. Increased vocalizations were interpreted as a negative response.

The researchers concluded feeding frequency did not influence total sow removal or the proportion of sows removed for reproductive failure. Although relatively few sows were removed for structural problems, those that were removed were on the twice/day feeding frequency.

Gilts experienced no influence of feeding frequency on removal from the trial because of reproductive failure or structural problems.

Increasing feeding frequency from two to six times/day had no effect on overall gain, average daily gain and backfat change in the sow group.

Increasing the feeding frequency for the gilts did not affect weight gain from Days 0 to 42 of gestation; however, there was a trend for gilts fed six times/day to have a greater average daily gain. Therefore, gilts gained more weight from Days 0 to 42 compared to gilts fed twice/day. There were no differences in weight gain from Day 42 of gestation until farrowing. Thus, final weight was similar for the two feeding frequencies.

Among sows or gilts there were no differences in number born alive, stillbirths or mummies.

Sow aggressiveness was more pronounced, as determined by visual scores of skin and vulva lesions, when fed twice/day as compared to the sows fed six times/day. Gestating sows fed six times/day experienced less structural problems with feet, legs and hoofs. The researchers noted all scores were low, indicating relatively few structural or aggression problems.

Gilts demonstrated no differences for skin or vulva lesions, or leg and hoof scores during the research period.

The researchers concluded increasing the feeding frequency from two to six times/day does not have a dramatic impact on performance or welfare of group-housed gilts and sows.

Researchers: Jason Schneider; Mike Tokach; Steven Dritz, DVM; Robert Goodband; Jim Nelssen; Joel DeRouchey; Kansas State University. Contact Goodband at (785) 532-1228.

Virginiamycin Improves Phosphorus Utilization In Grow-Finish Pigs

University of Kentucky (UK) researchers recently conducted five experiments to determine if the antibiotic virginiamycin (Stafac) would impact phosphorus utilization in growing-finishing pigs, thus reducing phosphorus excretion in manure.

The feeding of low doses of antibiotics as growth promoters has been a common practice for over half a century. Although the mode of action of antibiotics on growth is primarily attributed to their effects on animal health, they have also been shown to have a positive effect on energy and nitrogen utilization in swine and other animals. Whether antibiotics have an effect on mineral utilization is not known, but some poultry research suggests certain antibiotics may benefit phosphorus utilization.

The first four experiments were conducted with 70 crossbred barrows housed in metabolism crates. The pigs, 115 to 140 lb., were fed at 3% of their body weight, representing 85-90% of ad libitum intake.

Control pigs were fed a basal diet consisting of corn and soybean meal fortified with minerals and vitamins, but no supplemental phosphorus. A second treatment included the basal diet with 10 grams of virginiamycin per ton of feed. All of the phosphorus in the diets was supplied by the corn and soybean meal, thus most of the phosphorus in the diets were in the form of phytate, an organic form of phosphorus that is poorly available to pigs. Five-day balance experiments were conducted with complete, but separate, collection of feces and urine.

Table 1 shows the combined results of the four experiments. The addition of virginiamycin improved phosphorus digestibility. Even though pigs fed virginiamycin consumed more phosphorus, 7.20 g./day vs. 7.01 g./day, the antibiotic resulted in a 5-6% reduction in the amount of phosphorus excreted (4.57 g./day vs. 4.83 g./day).

Phosphorus excretion, expressed as a percent of intake, was reduced from 69% in control pigs to 63% in those fed the antibiotic. This means if the two groups of pigs had consumed the same amount of feed, the reduction in phosphorus excretion would have been approximately 9% in the virginiamycin-fed pigs compared with the controls.

A fifth experiment was conducted in an attempt to explain the reason for the improvement in phosphorus utilization in the virginiamycin-fed pigs.

In this study, 32 crossbred pigs, averaging 64 lb., were fed corn-soy diets with and without virginiamycin at 10 g./ton for 16 weeks to market weight. Samples were taken from the small intestine (ileum) after slaughtering the pigs to assess the bacterial profile. The most interesting effect of virginiamycin was an eight-fold increase in the number of phytate-utilizing bacteria in the gut of pigs fed the antibiotic.

The results suggest that the improvement in phosphorus utilization from the feeding of virginiamycin is related to a change in the bacterial profile in the small intestine, including a marked increase in the number of phytate-utilizing microorganisms.

The inclusion of virginiamycin in growing-finishing diets is an additional tool that can be used to improve phosphorus utilization, thus reducing phosphorus excretion in swine manure.

Researchers: Merlin D. Lindemann, Jorge H. Agudelo, Gary L. Cromwell and Melissa C. Newman, University of Kentucky, Lexington. Contact Lindemann at (859) 257-7527.